General Internal Medicine

210 questions

All types210 Multiple choice106 Matching52 Ordering52

A 67-year-old woman is brought to the emergency department by her daughter due to increasing confusion, rapid breathing, and generalized weakness that started yesterday. The daughter notes that the patient has been complaining of a "constant buzzing" in her ears for the past 24 hours. The patient has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of 35%, type 2 diabetes mellitus, and severe bilateral knee osteoarthritis. Her current medications include metoprolol, lisinopril, empagliflozin, and several over-the-counter analgesics that she has been taking frequently due to a recent pain flare.

Vital signs are:
Temperature: 38.3°C (100.9°F)
Heart rate: 118/min
Respiratory rate: 32/min
Blood pressure: 105/65 mm Hg
Oxygen saturation: 97% on room air

Physical examination reveals a disoriented patient taking deep, rapid breaths. Chest auscultation demonstrates scattered bilateral basilar crackles. Cardiac examination shows a regular, rapid rhythm with no murmurs, gallops, or jugular venous distention. Trace bilateral pedal edema is present.

Laboratory results:
Serum sodium: 142 mEq/L
Serum potassium: 3.4 mEq/L
Serum chloride: 100 mEq/L
Serum bicarbonate: 14 mEq/L
Blood urea nitrogen: 32 mg/dL
Serum creatinine: 1.6 mg/dL (baseline 1.1 mg/dL)

Arterial blood gas on room air:
pH: 7.46
PaCO2: 20 mm Hg
PaO2: 88 mm Hg

Which of the following is the most appropriate next step in the management of this patient?

Intravenous sodium bicarbonate

Endotracheal intubation and mechanical ventilation

Intravenous furosemide

Intravenous ceftriaxone and azithromycin

Measurement of serum thyroid-stimulating hormone

Show answer & explanation

Answer: Intravenous sodium bicarbonate

Answer

Intravenous sodium bicarbonate

The correct intervention is intravenous sodium bicarbonate. This patient's presentation of tinnitus, hyperthermia, noncardiogenic pulmonary edema, altered mental status, and a history of excessive over-the-counter analgesic use is highly suspicious for salicylate toxicity. The diagnosis is confirmed by her arterial blood gas and basic metabolic panel, which reveal the hallmark mixed acid-base disorder of salicylate poisoning: a primary respiratory alkalosis (due to direct stimulation of the medullary respiratory center) and a primary high anion gap metabolic acidosis (due to uncoupling of oxidative phosphorylation and accumulation of organic acids). Intravenous sodium bicarbonate acts to alkalinize both the serum and the urine. Serum alkalinization keeps the salicylate molecule in its ionized (deprotonated) state, preventing it from crossing the blood-brain barrier and causing central nervous system toxicity. Urine alkalinization promotes 'ion trapping' in the renal tubules, significantly increasing renal clearance of the drug.

Step-by-Step Solution

Analyze the arterial blood gas (ABG) to determine the primary acid-base disorder.

The pH is 7.46 (alkalemia). The

PaCO_2

is 20 mm Hg (low). The

HCO_3^-

is 14 mEq/L (low). Since the pH is high and the

PaCO_2

is low, the primary disorder is a respiratory alkalosis.

Establishing the initial primary disorder is the first step in diagnosing complex acid-base abnormalities.

Calculate expected compensation to evaluate for mixed acid-base disorders.

For acute respiratory alkalosis, expected

HCO_3^-

drops by 2 mEq/L for every 10 mm Hg drop in

PaCO_2

. The

PaCO_2

dropped by 20 (from 40 to 20), so

HCO_3^-

should drop by 4. Expected

HCO_3^- = 24 - 4 = 20

mEq/L. The actual

HCO_3^-

is 14 mEq/L. Because the actual bicarbonate is much lower than the expected compensatory level, there is a concomitant primary metabolic acidosis.

Whenever actual compensatory values differ significantly from expected values, a secondary primary disorder is present.

Calculate the anion gap to characterize the metabolic acidosis.

Anion Gap (AG)

= Na^+ - (Cl^- + HCO_3^-) = 142 - (100 + 14) = 28

mEq/L. This confirms a high anion gap metabolic acidosis (HAGMA).

HAGMA narrows the differential diagnosis to specific causes such as ketoacidosis, lactic acidosis, renal failure, or ingestions (MUDPILES).

Synthesize the laboratory data with the clinical presentation.

The patient has a primary respiratory alkalosis + primary HAGMA. Clinically, she presents with tinnitus ('buzzing' in ears), hyperthermia, tachypnea, and noncardiogenic pulmonary edema (crackles without JVD/S3) after taking over-the-counter analgesics. This is the classic presentation of severe salicylate (aspirin) toxicity.

Salicylates directly stimulate the medullary respiratory center (causing respiratory alkalosis) and later uncouple oxidative phosphorylation (causing lactic acidosis/HAGMA).

Determine the definitive treatment for the diagnosed condition.

The treatment for severe salicylate toxicity is intravenous sodium bicarbonate.

Sodium bicarbonate alkalinizes the blood, keeping salicylate in its ionized form so it cannot cross the blood-brain barrier. It also alkalinizes the urine, trapping the salicylate ion in the renal tubules and promoting its excretion.

Key Concept

Diagnosis and management of a mixed primary respiratory alkalosis and primary high anion gap metabolic acidosis secondary to salicylate toxicity.

Question 2Question →

Paramedics bring an 81-year-old female to the acute care unit from her assisted living facility. Staff members called for help after noticing she was acting confused and breathing rapidly since she woke up. Her medical history is notable for severe osteoarthritis, hypertension, and diet-controlled type 2 diabetes mellitus. According to the facility's notes, she had been complaining of a constant "ringing" sound in her ears for the past 48 hours and self-administering extra over-the-counter analgesics for knee pain.

On arrival, her temperature is 37.1°C (98.8°F), blood pressure is 135/85 mm Hg, pulse is 112/min, and respirations are 28/min. Oxygen saturation is 96% on ambient air.

The patient appears mildly lethargic and is oriented only to person. Her mucous membranes are notably dry. Auscultation of the chest reveals a rapid, regular heart rate with no murmurs, and breath sounds are clear in all lung fields. The abdomen is non-tender. Trace pitting edema is noted at the ankles.

Laboratory evaluation demonstrates:
Sodium: 142 mEq/L
Potassium: 3.9 mEq/L
Chloride: 102 mEq/L
Bicarbonate: 14 mEq/L
Blood urea nitrogen: 24 mg/dL
Creatinine: 1.2 mg/dL
Glucose: 105 mg/dL

Arterial blood gas analysis on ambient air reveals:
pH: 7.42
pCO2: 20 mm Hg
pO2: 92 mm Hg

Which of the following is the most appropriate next step in management for this patient?

Intravenous furosemide

Nebulized albuterol and ipratropium

Intravenous piperacillin-tazobactam

Intravenous sodium bicarbonate

Intravenous 0.9% sodium chloride and supportive observation

Show answer & explanation

Answer: Intravenous sodium bicarbonate

Answer

Intravenous sodium bicarbonate

This patient's clinical presentation (tinnitus, confusion, tachypnea) and laboratory findings (mixed high anion gap metabolic acidosis and primary respiratory alkalosis) are highly characteristic of salicylate toxicity. Salicylates directly stimulate the medullary respiratory center, causing early primary respiratory alkalosis. As toxicity progresses, the uncoupling of oxidative phosphorylation leads to the accumulation of organic acids, resulting in a concomitant high anion gap metabolic acidosis. This mixed disorder often keeps the pH near normal (e.g., 7.42). The next best step in management is to administer intravenous sodium bicarbonate. This alkalinizes the urine (target pH

\ge 7.5

), which converts lipophilic salicylic acid into its ionized, lipophobic form (salicylate). This 'ion trapping' prevents renal tubular reabsorption and significantly enhances the excretion of the toxin.

Step-by-Step Solution

Calculate the anion gap.

\text{Na}^+ - (\text{Cl}^- + \text{HCO}_3^-) = 142 - (102 + 14) = 26 \text{ mEq/L}

To identify the presence of a primary high anion gap metabolic acidosis.

Apply Winter's formula to determine the expected pCO2.

Expected

\text{pCO}_2 = (1.5 \times 14) + 8 = 29 \pm 2 \text{ mm Hg}

. The measured

\text{pCO}_2

20 \text{ mm Hg}

To assess whether respiratory compensation is appropriate or if a secondary acid-base disorder is present.

Synthesize the clinical and laboratory data.

The patient has a mixed high anion gap metabolic acidosis and primary respiratory alkalosis, accompanied by tinnitus and confusion in the setting of excessive analgesic use.

This triad of findings is pathognomonic for salicylate (aspirin) toxicity.

Determine the appropriate management.

Administer intravenous sodium bicarbonate.

To alkalinize the urine, which traps salicylate in its ionized form and enhances renal excretion.

Key Concept

Adults with salicylate toxicity classically present with a mixed high anion gap metabolic acidosis and primary respiratory alkalosis; the next best step in management is urine alkalinization with intravenous sodium bicarbonate.

Estimated Time:2m 0s

Question 3Question →

A 38-year-old woman comes to the clinic due to a 3-month history of worsening fatigue, generalized weakness, and a 4.5-kg (10-lb) weight gain despite a decreased appetite. She also reports feeling constantly cold and having increasingly irregular menstrual cycles. Her temperature is 36.1°C (97.0°F), blood pressure is 100/65 mm Hg, and pulse is 54/min. Physical examination shows dry skin and delayed relaxation of the deep tendon reflexes. Laboratory studies show a thyroid-stimulating hormone (TSH) level of 0.1 $\mu$ U/mL (normal: 0.5-5.0 $\mu$ U/mL) and a free thyroxine (T4) level of 0.4 ng/dL (normal: 0.9-1.7 ng/dL). Which of the following is the most likely cause of this patient's findings?

Autoimmune destruction of the thyroid gland

Thyroid-stimulating immunoglobulin production

Compression of pituitary thyrotrophs

Exogenous levothyroxine consumption

Decreased peripheral conversion of T4 to T3

Show answer & explanation

Answer: Compression of pituitary thyrotrophs

Answer

Compression of pituitary thyrotrophs, leading to central (secondary) hypothyroidism.

The correct answer identifies the etiology of central hypothyroidism. This patient has classic hypothyroid symptoms (fatigue, cold intolerance, weight gain, bradycardia), which correlates with her low free T4 level. However, her TSH is inappropriately suppressed rather than elevated. This lack of appropriate pituitary response indicates a central cause of hypothyroidism, most commonly resulting from a pituitary macroadenoma that causes mass effect and compression of normal thyrotrophs.

Step-by-Step Solution

Analyze the patient's symptoms and vital signs.

The patient presents with fatigue, weight gain, cold intolerance, bradycardia, and delayed deep tendon reflexes.

Identifying the clinical syndrome is the first step; these findings strongly suggest a hypothyroid state.

Interpret the thyroid function tests.

The free T4 is abnormally low, confirming hypothyroidism. The TSH is also abnormally low.

Normally, a low T4 should trigger an elevated TSH via negative feedback. An inappropriately low TSH in the setting of low T4 localizes the defect to the anterior pituitary or hypothalamus.

Determine the most likely etiology for the laboratory pattern.

The pattern indicates central hypothyroidism, which is most often caused by a pituitary mass.

A nonfunctioning pituitary adenoma can compress normal pituitary thyrotrophs, leading to decreased TSH production and subsequent hypothyroidism. This also commonly causes menstrual irregularities via compression of gonadotrophs or hyperprolactinemia due to stalk compression.

Key Concept

Central (secondary) hypothyroidism is characterized by clinical signs of hypothyroidism combined with a low free T4 and an inappropriately normal or low TSH.

Question 4Question →

A $24$ -year-old woman with type $1$ diabetes mellitus presents to the emergency department with abdominal pain, nausea, and Kussmaul respirations. She is diagnosed with diabetic ketoacidosis. Her initial laboratory results demonstrate a serum glucose of $600$ mg/dL and a serum potassium of $5.8$ mEq/L. She is tachycardic and hypotensive.

Arrange the following interventions in the correct chronological order as her treatment progresses over the next several hours.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Administer intravenous normal saline, 2) Initiate an intravenous regular insulin infusion, 3) Add potassium chloride when serum potassium falls below 5.2 mEq/L, and 4) Add 5% dextrose when serum glucose falls below 250 mg/dL.

The algorithmic management of diabetic ketoacidosis requires immediate intravascular volume expansion with normal saline to correct severe dehydration and improve tissue perfusion. Once fluids are running, intravenous regular insulin is started to halt lipolysis and ketogenesis. As insulin drives glucose and potassium into cells, serum potassium levels will predictably fall; thus, potassium chloride is added to the fluids once the level drops below

5.2

mEq/L to prevent dangerous hypokalemia. Finally, because the anion gap typically takes longer to close than the time it takes for glucose to normalize,

5\%

dextrose is added to the fluids once serum glucose reaches

200-250

mg/dL. This allows the continuation of the insulin infusion to clear ketones without causing hypoglycemia.

Step-by-Step Solution

Analyze the patient's presentation and baseline laboratory values.

The patient has diabetic ketoacidosis with severe hyperglycemia, hyperkalemia, and signs of intravascular volume depletion.

Establishing the baseline hemodynamic and electrolyte status is required to safely sequence the treatment steps.

Identify the primary and most immediate life-saving intervention.

Administer a rapid bolus of intravenous normal saline.

Severe osmotic diuresis leads to profound dehydration. Restoring intravascular volume improves tissue perfusion and begins to lower glucose via renal clearance.

Determine the next pharmacologic step to reverse the underlying pathophysiology.

Initiate a continuous intravenous regular insulin infusion.

Because the initial potassium is elevated, it is safe to start insulin immediately after fluids to halt lipolysis and ketone production.

Anticipate the complications of insulin therapy and target electrolyte replacement.

Add potassium chloride when serum potassium falls below

5.2

mEq/L.

Total body potassium is depleted in diabetic ketoacidosis. As insulin shifts potassium into cells, serum levels will fall rapidly and require timely supplementation.

Determine the intervention needed when serum glucose begins to normalize but ketones persist.

Add

5\%

dextrose when serum glucose falls below

250

mg/dL.

Ketone clearance (closing the anion gap) takes longer than glucose normalization. Dextrose prevents hypoglycemia while allowing insulin to continue working.

Key Concept

The standard sequential management of diabetic ketoacidosis prioritizes immediate volume resuscitation, followed by insulin therapy, targeted electrolyte replacement, and eventually glucose supplementation to prevent hypoglycemia while clearing ketones.

Question 5Question →

A 66-year-old man is brought to the emergency department by his wife due to severe, progressively worsening shortness of breath over the past 24 hours. He has a history of essential hypertension, type 2 diabetes mellitus, and a 45-pack-year smoking history. The patient reports a dry, hacking cough. His wife notes that he has been sleeping in his recliner for the past two nights because he feels like he is "smothering" when lying flat in bed.

Temperature is 37.0°C (98.6°F), blood pressure is 175/100 mm Hg, pulse is 112/min, and respirations are 26/min. Oxygen saturation is 89% on room air. The patient is diaphoretic, sitting upright, and using accessory muscles of respiration. Jugular venous pressure is estimated at 10 cm H2O. Pulmonary auscultation reveals a prolonged expiratory phase with diffuse, loud, bilateral expiratory wheezes; no crackles are appreciated. Cardiac auscultation reveals a regular tachycardia with a prominent S4 gallop. Trace bilateral pitting edema is present at the ankles.

Laboratory results are as follows:
Sodium: 138 mEq/L
Potassium: 4.2 mEq/L
Chloride: 104 mEq/L
Bicarbonate: 16 mEq/L
Blood urea nitrogen: 30 mg/dL
Serum creatinine: 1.6 mg/dL
Lactate: 4.1 mmol/L
Thyroid-stimulating hormone: 2.5 µU/mL (normal: 0.5-5.0 µU/mL)
Free T4: 0.6 ng/dL (normal: 0.9-2.4 ng/dL)

An arterial blood gas on room air reveals:
pH: 7.30
pCO2: 33 mm Hg
pO2: 64 mm Hg

A chest radiograph demonstrates cardiomegaly, peribronchial cuffing, and prominent upper lobe vessels, with no focal consolidations.

Which of the following is the most appropriate next step in management for this patient?

Intravenous furosemide

Nebulized albuterol and intravenous methylprednisolone

Immediate endotracheal intubation

Empiric intravenous levofloxacin

Initiation of oral levothyroxine

Show answer & explanation

Answer: Intravenous furosemide

Answer

Intravenous furosemide

The correct answer is the administration of a loop diuretic. This patient is presenting with acute decompensated heart failure (ADHF). Although his 45-pack-year smoking history and prominent wheezing might initially suggest a chronic obstructive pulmonary disease (COPD) exacerbation, several key features point to cardiogenic pulmonary edema. The presence of orthopnea (sleeping in a recliner), elevated jugular venous pressure, an S4 gallop (indicating a stiff, non-compliant left ventricle), and trace pedal edema are classic signs of fluid overload and heart failure. Furthermore, the chest radiograph shows cardiomegaly and peribronchial cuffing. The wheezing is a manifestation of 'cardiac asthma,' where perivascular and peribronchial interstitial edema compresses the small airways, mimicking primary bronchospasm. The most appropriate initial step in management is the administration of an intravenous loop diuretic to reduce intravascular volume and relieve pulmonary congestion.

Step-by-Step Solution

Evaluate the clinical presentation and radiographic findings to determine the primary diagnosis.

Identify that the patient has acute decompensated heart failure (ADHF) presenting as 'cardiac asthma.'

Despite the smoking history and prominent wheezing, the presence of orthopnea, elevated JVP, an S4 gallop, cardiomegaly, and peribronchial cuffing strongly point to cardiogenic pulmonary edema rather than a COPD exacerbation.

Analyze the basic metabolic panel and arterial blood gas to assess for potential respiratory failure.

Calculate the anion gap (18) and apply Winter's formula to find the expected pCO2 is 32 ± 2 mm Hg.

The actual pCO2 of 33 mm Hg falls within the expected range, confirming appropriate respiratory compensation for the lactic acidosis. The patient is not in hypercapnic respiratory failure.

Interpret the thyroid panel in the context of acute critical illness.

Recognize the low free T4 and normal TSH as euthyroid sick syndrome (non-thyroidal illness syndrome).

In acute illness, peripheral conversion of T4 to T3 is altered. Thyroid hormone replacement is not indicated.

Select the most appropriate next step in management based on the primary diagnosis.

Select intravenous furosemide to rapidly reduce volume overload.

Loop diuretics are the first-line therapy for symptomatic relief in acute decompensated heart failure.

Key Concept

Differentiating acute decompensated heart failure ('cardiac asthma') from COPD exacerbation, and interpreting mixed acid-base disorders using Winter's formula to guide management.

Estimated Time:2m 0s

Question 6Question →

A 54-year-old man with a history of alcohol use disorder and liver cirrhosis is brought to the emergency department vomiting bright red blood. His blood pressure is 85/55 mm Hg, and his pulse is 122/min. Arrange the following management steps in the most appropriate sequential order.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Volume resuscitation, followed by targeted medical therapy (octreotide and ceftriaxone), followed by endoscopy, and finally reserving TIPS as a last resort.

The management of acute variceal hemorrhage follows a strict algorithmic approach prioritizing fundamental resuscitation principles. Initial management must focus on hemodynamic stabilization with volume resuscitation via large-bore intravenous catheters. Concurrently or immediately following, empiric medical therapy with a splanchnic vasoconstrictor (such as octreotide) and prophylactic antibiotics (such as ceftriaxone) should be given to decrease portal pressure and prevent infectious complications, which are major drivers of mortality. Once the patient is stabilized, urgent esophagogastroduodenoscopy is indicated for definitive diagnosis and treatment, typically variceal band ligation. TIPS is reserved exclusively as a rescue therapy for patients who fail endoscopic control.

Step-by-Step Solution

Prioritize immediate circulatory stabilization.

Placement of large-bore IVs and fluid administration.

The patient has hypotension and tachycardia indicating severe volume loss; the ABCs (Airway, Breathing, Circulation) always come first.

Implement targeted empiric medical therapy for suspected variceal bleeding.

Administration of intravenous octreotide and ceftriaxone.

Octreotide reduces portal pressures, and antibiotics significantly decrease mortality and rebleeding rates in cirrhotics. These must be given prior to endoscopy.

Proceed with definitive diagnostic and therapeutic procedures.

Urgent esophagogastroduodenoscopy (EGD) for potential variceal band ligation.

Endoscopy identifies the source of bleeding and provides mechanical hemostasis once the patient is adequately resuscitated.

Evaluate the need for rescue therapies.

Consideration of transjugular intrahepatic portosystemic shunt (TIPS).

TIPS has high rates of complications like encephalopathy and is strictly reserved for cases refractory to medical and endoscopic management.

Key Concept

Algorithmic sequence for acute variceal hemorrhage management: Resuscitation -> Medical Therapy -> Endoscopic Therapy -> Rescue Therapy.

Question 7Question →

A 72-year-old man is brought to the emergency department by his son due to worsening shortness of breath, increased cough, and progressive lethargy over the past 48 hours. The son notes that the patient's baseline morning cough has been producing thick, yellowish sputum since yesterday. The patient has a history of severe chronic obstructive pulmonary disease (COPD) and hypertension. His temperature is 38.1°C (100.6°F), blood pressure is 134/82 mm Hg, pulse is 108/min, and respirations are 26/min. Pulse oximetry shows 88% on room air. Physical examination reveals an increased anteroposterior chest diameter. Lung auscultation demonstrates bilateral diffuse wheezing and a prolonged expiratory phase. There are no crackles, jugular venous distension, or lower extremity edema.

Laboratory testing shows:
Leukocyte count: 12,500/mm³
Thyroid-stimulating hormone (TSH): 2.5 µU/mL (normal: 0.5-5.0)
Free thyroxine (T4): 1.2 ng/dL (normal: 0.9-1.7)

Arterial blood gas on room air:
pH: 7.28
PaCO₂: 65 mm Hg
PaO₂: 55 mm Hg

Which of the following is the most appropriate initial pharmacological management?

Intravenous furosemide and sublingual nitroglycerin

Intravenous meropenem and vancomycin

Inhaled short-acting bronchodilators, systemic glucocorticoids, and oral azithromycin

Intravenous sodium bicarbonate

Intravenous levothyroxine and hydrocortisone

Show answer & explanation

Answer: Inhaled short-acting bronchodilators, systemic glucocorticoids, and oral azithromycin

Answer

Inhaled short-acting bronchodilators, systemic glucocorticoids, and oral azithromycin

This patient is experiencing an acute exacerbation of chronic obstructive pulmonary disease (AECOPD), characterized by the three cardinal symptoms: increased dyspnea, increased sputum volume, and increased sputum purulence. His lethargy and ABG findings (pH 7.28, PaCO2 65 mm Hg) indicate an acute respiratory acidosis due to progressive CO2 retention from severe airflow obstruction. The appropriate initial pharmacological management includes inhaled short-acting bronchodilators (albuterol/ipratropium) to relieve bronchospasm, systemic glucocorticoids to reduce airway inflammation, and a targeted antibiotic (such as oral azithromycin) to cover typical community-acquired respiratory pathogens (e.g., Haemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis).

Step-by-Step Solution

Identify the clinical syndrome based on the patient's symptoms.

The patient has increased dyspnea, increased cough, and purulent sputum, representing the three cardinal symptoms of an acute exacerbation of COPD.

Recognizing the cardinal symptoms establishes the primary diagnosis and directs specific therapy.

Rule out alternative causes of dyspnea and lethargy using exam and lab findings.

The absence of crackles, JVD, and edema makes heart failure unlikely. Normal TSH and T4 levels rule out myxedema coma as the cause of lethargy.

Overlapping presentations (like dyspnea in heart failure or lethargy in hypothyroidism) must be systematically excluded.

Interpret the acid-base status on the arterial blood gas.

The ABG shows an acute respiratory acidosis (pH 7.28, elevated PaCO2 65 mm Hg) secondary to poor ventilation, not a metabolic acidosis.

Accurate interpretation prevents inappropriate administration of buffering agents like sodium bicarbonate.

Select the appropriate pharmacologic package for the confirmed diagnosis.

The patient requires bronchodilators (for airflow), systemic glucocorticoids (for inflammation), and a targeted antibiotic like a macrolide (for infection).

This combination targets the bronchoconstriction, inflammation, and typical bacterial triggers of severe COPD exacerbations.

Key Concept

Management of acute exacerbations of COPD requires inhaled short-acting bronchodilators, systemic glucocorticoids, and appropriate targeted antibiotics when cardinal symptoms (increased dyspnea, sputum volume, and sputum purulence) are present.

Question 8Question →

An internal medicine rapid response team is activated for a $68$ -year-old hospitalized male who developed profound lower extremity weakness and lethargy. The patient was admitted two days ago for a diabetic foot infection and is receiving intravenous piperacillin-tazobactam. His home medications, including lisinopril and spironolactone for heart failure with reduced ejection fraction, were continued on admission. Over the past $12$ hours, his urine output has dropped significantly to $150$ mL. Vital signs demonstrate a heart rate of $42$ /min and a blood pressure of $98/60$ mmHg. A point-of-care basic metabolic panel reveals a serum potassium of $7.8$ mEq/L and a serum creatinine of $3.2$ mg/dL (baseline $1.4$ mg/dL). A stat $12$ -lead electrocardiogram demonstrates widened QRS complexes, absent P waves, and peaked T waves.

Arrange the following management steps in the most appropriate chronological sequence for this patient's acute presentation, from the most immediate intervention to subsequent actions.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Administer intravenous calcium gluconate, 2) Infuse intravenous regular insulin with dextrose, 3) Administer an enteral potassium-binding resin, 4) Discontinue lisinopril and spironolactone, 5) Prepare for urgent hemodialysis.

The algorithm for severe hyperkalemia dictates that life-saving membrane stabilization with intravenous calcium (onset 1-3 minutes) must occur first. This is immediately followed by agents that shift potassium into cells (insulin/dextrose, onset 15-30 minutes) to buy time. Next, definitive elimination therapies like gastrointestinal binders (onset 2-6 hours) are given, alongside stopping offending agents (ACE inhibitors/MRAs) to prevent recurrence. Finally, if conservative measures fail or the patient remains anuric, hemodialysis serves as the ultimate rescue therapy.

Step-by-Step Solution

Recognize severe, symptomatic hyperkalemia with cardiotoxicity.

Identification of a life-threatening emergency requiring immediate membrane stabilization.

The patient's potassium is critically high (

7.8

mEq/L) with corresponding bradycardia and widened QRS complexes, indicating imminent risk of cardiac arrest.

Prioritize rapid-acting pharmacological interventions based on time to onset.

Intravenous calcium gluconate is administered first (onset 1-3 minutes), followed by insulin and dextrose (onset 15-30 minutes).

Myocardial stabilization must occur before shifting agents take effect to prevent fatal arrhythmias during the interim.

Implement measures for total body potassium reduction and secondary prevention.

Gastrointestinal binders are administered (onset in hours), and offending medications are halted.

Intracellular shifting is only temporary. True elimination of potassium is required for definitive resolution.

Establish a rescue plan for refractory hyperkalemia.

Preparation for hemodialysis is initiated.

The patient has severe acute kidney injury with oliguria, making pharmacological elimination unreliable.

Key Concept

The algorithmic pharmacological management of severe hyperkalemia follows a strict physiological hierarchy based on time-to-onset: membrane stabilization, followed by intracellular shifting, and finally, total body elimination.

Estimated Time:1m 30s

Question 9Question →

Match each patient presenting with severe hypertension and distinct clinical features to the most appropriate initial targeted pharmacologic intervention.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Aortic dissection requires beta-blockade; Scleroderma renal crisis requires ACE inhibition; Pheochromocytoma requires alpha-blockade; Flash pulmonary edema requires venodilation and diuresis.

Each specific hypertensive emergency demands a precise pharmacological mechanism of action to counteract its pathophysiology. Using a generic approach for blood pressure lowering without addressing the specific underlying driver can lead to severe adverse outcomes.

Step-by-Step Solution

Analyze the clinical features of each patient to establish the underlying diagnosis causing the hypertensive emergency.

Identified diagnoses are acute aortic dissection, scleroderma renal crisis, pheochromocytoma crisis, and acute decompensated heart failure (flash pulmonary edema).

Accurate diagnosis is required because standard hypertensive emergency protocols vary drastically based on the target organ damage.

Identify the primary pathophysiological driver for each condition.

Drivers: shear stress (dissection), RAAS activation (scleroderma), catecholamine surge (pheochromocytoma), and high preload/afterload (flash pulmonary edema).

Understanding the mechanism allows for targeted pharmacotherapy rather than generic blood pressure reduction.

Match the diagnosis to the pharmacologic agent that specifically targets that pathophysiologic mechanism.

Matched esmolol to dissection, captopril to scleroderma, phentolamine to pheochromocytoma, and nitroglycerin/diuretics to heart failure.

This pairs the optimal intervention with the specific life-threatening condition while avoiding harmful contraindications.

Key Concept

Targeted pharmacotherapy for specific hypertensive emergencies based on underlying pathophysiology.

Estimated Time:1m 30s

Question 10Question →

An emergency medical services team transports a $68$ -year-old retired teacher to the emergency department due to rapidly progressive breathlessness that awoke her from sleep. She has a medical history significant for a myocardial infarction three years ago and moderate chronic obstructive pulmonary disease, for which she uses an as-needed albuterol inhaler. Over the past $12$ hours, her inhaler has provided no relief. Her home medications include aspirin, metoprolol, and lisinopril.

On arrival, her temperature is $37.0^\circ \text{C}$ ( $98.6^\circ \text{F}$ ), blood pressure is $178/104 \text{ mm Hg}$ , pulse is $112/\text{min}$ , and respiratory rate is $28/\text{min}$ . Oxygen saturation is $86\%$ on room air. The patient appears highly anxious and is sitting upright on the stretcher. Physical examination reveals distended jugular veins when sitting at a $45^\circ$ angle. Pulmonary auscultation reveals diffuse expiratory wheezing with a prolonged expiratory phase, as well as bilateral bibasilar crackles. Cardiac examination demonstrates a regular tachycardia with a prominent early diastolic extra heart sound.

Arterial blood gas analysis on room air shows:
- pH: $7.28$
- $\text{PaCO}_2$ : $56 \text{ mm Hg}$
- $\text{PaO}_2$ : $54 \text{ mm Hg}$
- $\text{HCO}_3^-$ : $25 \text{ mEq/L}$

Which of the following is the most appropriate initial pharmacological intervention for this patient?

Intravenous furosemide

Intravenous methylprednisolone

Continuous albuterol nebulization

Intravenous ceftriaxone and azithromycin

Intravenous sodium bicarbonate

Show answer & explanation

Answer: Intravenous furosemide

Answer

Intravenous furosemide is the most appropriate initial management to reduce preload and treat acute decompensated heart failure.

The correct answer provides a medication that rapidly reduces cardiac preload. The patient is experiencing acute decompensated heart failure (ADHF) manifesting as flash pulmonary edema. This is evidenced by her acute dyspnea, hypertension, hypoxemia, jugular venous distention, crackles, and an S3 gallop (an early diastolic extra heart sound strongly associated with elevated left ventricular end-diastolic pressure). The diffuse wheezing is 'cardiac asthma', a condition where peribronchial edema causes airway narrowing that mimics primary lung disease. Initial management for ADHF relies on intravenous loop diuretics (like furosemide) and/or vasodilators to relieve pulmonary congestion.

Step-by-Step Solution

Analyze the patient's history and vital signs.

The patient has a history of ischemic heart disease and COPD. She is presenting with severe acute hypoxemia, tachypnea, and significant hypertension (

178/104 \text{ mm Hg}

Identifying the baseline risk factors and hemodynamic status helps narrow the differential diagnosis for acute respiratory distress.

Synthesize the physical examination findings.

The exam shows jugular venous distention, bibasilar crackles, an S3 gallop (early diastolic extra sound), and diffuse wheezing.

An S3 gallop and elevated jugular venous pressure are highly specific for left and right-sided heart failure. The wheezing represents 'cardiac asthma' resulting from peribronchial edema, not a primary bronchospastic event.

Interpret the arterial blood gas (ABG) results.

The ABG reveals pH

7.28

\text{PaCO}_2

56 \text{ mm Hg}

, and

\text{HCO}_3^-

25 \text{ mEq/L}

, indicating acute respiratory acidosis secondary to poor ventilation from pulmonary edema.

Correctly identifying the acid-base disorder prevents the inappropriate administration of alkalizing agents like bicarbonate.

Determine the next best step in management.

The diagnosis is acute decompensated heart failure (ADHF) presenting as flash pulmonary edema. The standard initial therapy is intravenous loop diuretics (e.g., furosemide) or vasodilators (e.g., nitroglycerin).

These agents rapidly decrease central venous pressure and pulmonary capillary wedge pressure, immediately improving pulmonary congestion and gas exchange.

Key Concept

Patients with acute decompensated heart failure may present with wheezing (cardiac asthma) that mimics a COPD exacerbation; the presence of an S3 gallop, jugular venous distention, and bibasilar crackles confirms a cardiogenic etiology requiring diuresis or vasodilation.

Question 11Question →

Match each patient's preoperative medication profile with the most appropriate perioperative management strategy for that specific medication.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Empagliflozin is stopped 3-4 days prior. Lisinopril is held the morning of surgery. Warfarin is stopped 5 days prior with LMWH bridging. Methotrexate is continued without interruption. Rivaroxaban is stopped 2-3 days prior without bridging.

Preoperative optimization requires individualized medication adjustments based on pharmacokinetics and surgical stress. SGLT2 inhibitors (empagliflozin) are stopped 3 to 4 days prior to avoid euglycemic DKA. ACE inhibitors (lisinopril) are held the morning of surgery to prevent severe vasoplegia. High-risk thromboembolic conditions (mechanical mitral valve) require warfarin cessation 5 days prior with LMWH bridging. DOACs (rivaroxaban) are held 2 to 3 days prior without bridging due to their rapid offset. Non-biologic DMARDs (methotrexate) are continued in stable rheumatoid arthritis to prevent disease flares that hinder recovery.

Step-by-Step Solution

Identify the indication and mechanism for empagliflozin.

It is an SGLT2 inhibitor used for diabetes.

SGLT2 inhibitors increase the risk of euglycemic DKA during perioperative fasting, requiring cessation 3-4 days prior.

Evaluate the surgical risk and indication for warfarin.

Mechanical mitral valve indicates high thromboembolic risk.

High-risk indications require heparin bridging when warfarin is stopped 5 days before surgery.

Assess the mechanism and offset of rivaroxaban.

It is a short-acting DOAC.

DOACs do not require bridging; they are simply held 2-3 days before moderate-to-high bleeding risk procedures.

Determine the perioperative risk of lisinopril.

ACE inhibitors can cause vasoplegic shock.

Holding the morning dose mitigates the risk of severe intraoperative hypotension under general anesthesia.

Analyze the management of methotrexate in stable rheumatoid arthritis.

Continuing is preferred over discontinuation.

The risk of a severe disease flare outweighs the theoretical risk of perioperative infection when holding methotrexate.

Key Concept

Optimal perioperative medication management involves balancing surgical risks (e.g., bleeding, hypotension, ketoacidosis) against the risk of underlying disease exacerbation.

Estimated Time:2m 0s

Question 12Question →

Review the following clinical presentations of patients with severe malabsorption or those receiving long-term parenteral nutrition. Match each clinical vignette to the specific underlying trace mineral deficiency it describes.

Click a left item, then click its matching right item

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Answer

Vignette 1 matches with Copper deficiency; Vignette 2 matches with Zinc deficiency; Vignette 3 matches with Selenium deficiency; Vignette 4 matches with Chromium deficiency.

Each clinical syndrome specifically maps to the pathognomonic findings of isolated trace mineral deficiencies that occur predominantly in the context of prolonged parenteral nutrition or severe gastrointestinal malabsorption.

Step-by-Step Solution

Analyze the first vignette featuring neurologic deficits (spastic paraparesis, sensory ataxia) combined with microcytic anemia and neutropenia in a post-bariatric surgery patient.

Identify Copper deficiency.

While the neurologic findings suggest posterior column and corticospinal tract demyelination similar to vitamin B12 deficiency, the normal B12 level and the presence of microcytic anemia with leukopenia are pathognomonic for copper deficiency.

Evaluate the second vignette describing a periorificial rash, alopecia, diarrhea, and dysgeusia in a patient with malabsorption.

Identify Zinc deficiency.

This is the classic presentation of acquired zinc deficiency, analogous to the genetic condition acrodermatitis enteropathica. The combination of periorificial skin lesions and dysgeusia is a hallmark.

Examine the third vignette describing dilated cardiomyopathy and myopathy in a patient on prolonged parenteral nutrition.

Identify Selenium deficiency.

Selenium deficiency is strongly associated with endemic Keshan disease (cardiomyopathy) and skeletal myopathy due to impaired cellular antioxidant defenses.

Assess the fourth vignette involving refractory hyperglycemia and neuropathy in a parenteral nutrition-dependent patient.

Identify Chromium deficiency.

Chromium potentiates insulin action. Its absence leads to severe glucose intolerance and insulin resistance, often manifesting rapidly when omitted from parenteral nutrition formulas.

Key Concept

Trace element deficiencies in the setting of severe malabsorption or long-term parenteral nutrition present with highly specific, identifiable clinical syndromes that require targeted recognition and replacement.

Question 13Question →

A 64-year-old woman is brought to the emergency department by her son due to worsening confusion, nausea, and ringing in her ears for the past 24 hours. She has a history of chronic obstructive pulmonary disease (COPD), hypertension, and osteoarthritis, for which she frequently takes over-the-counter analgesics. She also underwent transsphenoidal resection of a pituitary macroadenoma 5 years ago.

Vital signs: Temperature 37.1°C (98.8°F), blood pressure 110/70 mmHg, heart rate 112/min, respiratory rate 28/min.

Physical examination reveals dry mucous membranes and lethargy. Lung auscultation reveals clear breath sounds bilaterally. There is no jugular venous distention.

Laboratory results:
Sodium: 141 mEq/L
Potassium: 3.9 mEq/L
Chloride: 105 mEq/L
Bicarbonate: 14 mEq/L
Blood urea nitrogen: 38 mg/dL
Creatinine: 1.8 mg/dL
Thyroid-stimulating hormone (TSH): 1.1 µU/mL (normal: 0.4–4.0 µU/mL)
Free T4: 0.5 ng/dL (normal: 0.9–1.7 ng/dL)

Arterial blood gas on room air:
pH: 7.42
$PaCO_2$ : 22 mmHg
$PaO_2$ : 96 mmHg

A urine culture sent 3 days ago from an outpatient clinic visit for mild dysuria has returned positive for $>100,000$ CFU/mL of *Escherichia coli*, which is susceptible to cephalexin and nitrofurantoin, but resistant to fluoroquinolones.

Which of the following is the most appropriate next step in management?

Intravenous sodium bicarbonate

Intravenous 0.9% normal saline and observation

Intravenous furosemide

Intravenous piperacillin-tazobactam

Initiation of levothyroxine

Show answer & explanation

Answer: Intravenous sodium bicarbonate

Answer

Intravenous sodium bicarbonate

The correct intervention is intravenous sodium bicarbonate. This patient presents with characteristic features of salicylate (aspirin) toxicity, specifically tinnitus, nausea, tachypnea, and altered mental status. Salicylates cause a classic mixed acid-base disorder. They directly stimulate the medullary respiratory center, causing hyperventilation and a primary respiratory alkalosis. Simultaneously, they uncouple oxidative phosphorylation, leading to the accumulation of unmeasured organic acids and a primary high anion gap metabolic acidosis (AG =

141 - (105 + 14) = 22

). Winter's formula shows an expected

PaCO_2

29 \pm 2

mmHg; the measured

PaCO_2

of 22 mmHg confirms a concomitant primary respiratory alkalosis. The near-normal pH of 7.42 is a typical feature of this mixed disorder. Treatment focuses on stabilizing the patient and alkalinizing the urine with continuous intravenous sodium bicarbonate. Alkalinization converts salicylic acid into its ionized, lipophobic form in the renal tubules, trapping it in the urine and significantly enhancing its excretion.

Step-by-Step Solution

Analyze the acid-base status using the provided arterial blood gas and basic metabolic panel.

The anion gap is calculated as

141 - (105 + 14) = 22

mEq/L, indicating a primary high anion gap metabolic acidosis. The pH is unexpectedly normal (7.42).

Determining the primary disorder and calculating the anion gap are the first steps in evaluating any acid-base derangement.

Calculate expected respiratory compensation using Winter's formula.

Expected

PaCO_2 = 1.5 \times 14 + 8 \pm 2 = 29 \pm 2

mmHg. The actual

PaCO_2

is 22 mmHg, which is significantly lower than expected.

If the measured

PaCO_2

falls outside the expected range, a secondary primary acid-base disorder is present. In this case, there is a concurrent primary respiratory alkalosis.

Correlate the mixed acid-base disorder with the clinical presentation.

A mixed high anion gap metabolic acidosis and primary respiratory alkalosis in a patient with tinnitus (ringing in ears) points to salicylate (aspirin) toxicity.

Salicylates directly stimulate the medullary respiratory center (respiratory alkalosis) and uncouple oxidative phosphorylation, leading to the accumulation of organic acids (metabolic acidosis).

Determine the definitive treatment for the identified toxicity.

Administration of intravenous sodium bicarbonate is required.

Sodium bicarbonate alkalinizes the blood and urine. Alkalemia promotes the movement of salicylates out of the central nervous system, while alkalinized urine traps the ionized form of salicylate, accelerating its excretion.

Key Concept

Patients with severe salicylate toxicity classically present with a mixed primary respiratory alkalosis and primary high anion gap metabolic acidosis. Treatment includes intravenous sodium bicarbonate to alkalinize the urine and enhance salicylate excretion.

Estimated Time:1m 30s

Question 14Question →

A 68-year-old man is evaluated in the hospital on day 4 of admission for persistent low-grade fevers and fatigue. He originally presented with a 2-week history of generalized weakness, night sweats, and shortness of breath. His medical history is significant for hypertension and osteoarthritis. On examination today, temperature is 37.8°C (100.0°F), blood pressure is 128/76 mmHg, and pulse is 88/min. Cardiac auscultation reveals a new grade 3/6 holosystolic murmur heard best at the cardiac apex. Laboratory studies show a leukocyte count of 12,400/mm³ and serum creatinine of 1.4 mg/dL (baseline 0.9 mg/dL). Blood cultures drawn at admission have grown *Enterococcus faecalis* in 4 out of 4 bottles. Susceptibility testing demonstrates the isolate is susceptible to ampicillin, vancomycin, and linezolid, and lacks high-level aminoglycoside resistance. A transesophageal echocardiogram shows a 1.2-cm mobile vegetation on the mitral valve. The patient is currently receiving empiric therapy with intravenous vancomycin and cefepime. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

Discontinue current antibiotics and initiate intravenous ampicillin and ceftriaxone

Continue both intravenous vancomycin and cefepime

Discontinue cefepime and continue intravenous vancomycin monotherapy

Discontinue current antibiotics and initiate intravenous daptomycin

Discontinue cefepime and add intravenous gentamicin to the vancomycin regimen

Show answer & explanation

Answer: Discontinue current antibiotics and initiate intravenous ampicillin and ceftriaxone

Answer

The correct step is to discontinue the broad-spectrum empiric antibiotics and initiate targeted therapy with intravenous ampicillin and ceftriaxone.

The most appropriate management is transitioning to intravenous ampicillin and ceftriaxone. *Enterococcus faecalis* endocarditis requires prolonged, bactericidal combination therapy. When the isolate is susceptible, ampicillin is the preferred beta-lactam backbone. Because ampicillin alone is only bacteriostatic against *Enterococcus*, synergy is required to achieve bactericidal activity for deep-seated infections. This synergy is traditionally achieved by adding an aminoglycoside (e.g., gentamicin) or a third-generation cephalosporin (ceftriaxone). In a patient with acute kidney injury (evidenced by a rising serum creatinine from 0.9 to 1.4 mg/dL), the ampicillin and ceftriaxone combination is highly preferred due to comparable efficacy and a significantly lower risk of nephrotoxicity. Discontinuing the empiric vancomycin and cefepime correctly follows antibiotic stewardship protocols by narrowing the spectrum of coverage.

Step-by-Step Solution

Interpret the clinical presentation, imaging, and laboratory data.

The patient has native-valve *Enterococcus faecalis* infective endocarditis, complicated by a mild acute kidney injury (elevated creatinine).

Four positive blood cultures, a new regurgitant murmur, and a valvular vegetation on echocardiography confirm the diagnosis. The rising creatinine establishes the renal impairment.

Determine the optimal antibiotic backbone based on susceptibility and stewardship principles.

Ampicillin must be selected as the primary agent.

De-escalating from broad-spectrum empiric therapy (vancomycin) to a targeted, narrow-spectrum agent (ampicillin) for susceptible organisms is a foundational rule of antibiotic stewardship.

Identify the need for bactericidal synergy and select the safest secondary agent.

Ceftriaxone is added to ampicillin instead of an aminoglycoside.

Ampicillin is only bacteriostatic against *Enterococcus*; endocarditis requires bactericidal synergy. While gentamicin provides synergy, ceftriaxone provides equal synergistic efficacy with significantly less nephrotoxicity, making it the drug of choice in patients with existing renal impairment.

Key Concept

De-escalation of empiric antibiotics to targeted synergistic therapy (ampicillin and ceftriaxone) for *Enterococcus faecalis* endocarditis, prioritizing nephron-sparing regimens in the setting of acute kidney injury.

Estimated Time:1m 30s

Question 15Question →

Match each clinical presentation to the most appropriate initial therapeutic intervention.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Hyperkalemia with ECG changes requires calcium gluconate; delirium tremens requires lorazepam; spontaneous bacterial peritonitis requires cefotaxime; acute decompensated heart failure requires furosemide.

Each clinical presentation describes a classic acute medical emergency requiring a specific, immediate intervention. Hyperkalemia with QRS widening necessitates immediate cardiac membrane stabilization with calcium gluconate. Delirium tremens requires prompt symptom control with intravenous benzodiazepines like lorazepam. Spontaneous bacterial peritonitis, diagnosed by an ascitic neutrophil count greater than 250/mm³, requires urgent empiric antibiotics such as cefotaxime. Acute decompensated heart failure with signs of fluid overload is initially managed with an intravenous loop diuretic like furosemide to provide rapid symptom relief.

Step-by-Step Solution

Analyze each clinical vignette to establish the most likely acute primary diagnosis.

The diagnoses are severe hyperkalemia, delirium tremens, spontaneous bacterial peritonitis, and acute decompensated heart failure.

Establishing the correct diagnosis is required to select the targeted initial therapeutic intervention.

Determine the most appropriate immediate management for each confirmed diagnosis.

Hyperkalemia with ECG changes requires calcium gluconate; delirium tremens requires benzodiazepines; SBP requires a third-generation cephalosporin; acute decompensated heart failure requires a loop diuretic.

These represent the standard-of-care initial treatments according to current clinical guidelines.

Match the clinical presentations with their corresponding therapeutic interventions.

The correct pairs are formed based on the established diagnoses and their respective evidence-based treatments.

This completes the requirement of the matching task.

Key Concept

Initial management of acute internal medicine emergencies

Question 16Question →

Match each patient's clinical presentation following a toxic ingestion or medication overdose to the most appropriate initial specific pharmacologic antidote or therapy.

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Answer

The presentations match their specific antidotes as follows: the patient with opioid toxicity requires naloxone; the patient with acetaminophen hepatotoxicity requires N-acetylcysteine; the patient with beta-blocker overdose requires glucagon; the patient with tricyclic antidepressant cardiotoxicity requires sodium bicarbonate; and the patient with digoxin toxicity requires digoxin-specific antibody fragments.

Each clinical vignette presents a classic toxic ingestion that dictates a specific antidote. Opioid overdose (miosis, respiratory depression) is reversed by naloxone. Acetaminophen overdose (hepatocellular injury) is treated with N-acetylcysteine. Beta-blocker overdose (bradycardia, hypoglycemia) is treated with glucagon. Tricyclic antidepressant overdose (anticholinergic toxicity, QRS widening) is treated with sodium bicarbonate. Digoxin toxicity (visual changes, arrhythmias) is treated with digoxin-specific antibody fragments.

Step-by-Step Solution

Analyze the first clinical presentation (respiratory depression, pinpoint pupils).

Identify opioid toxidrome.

The triad of miosis, CNS depression, and respiratory depression is pathognomonic for an opioid overdose.

Analyze the second clinical presentation (massive AST elevation after analgesic overdose).

Identify acetaminophen hepatotoxicity.

Acetaminophen is a common over-the-counter analgesic that causes acute liver failure in toxic doses.

Analyze the third clinical presentation (bradycardia, hypotension, hypoglycemia).

Identify beta-blocker overdose.

Beta-blockers reduce cardiac output and inhibit catecholamine-mediated glycogenolysis, leading to hypoglycemia.

Analyze the fourth clinical presentation (anticholinergic signs, QRS prolongation).

Identify tricyclic antidepressant (TCA) overdose.

TCAs block muscarinic receptors (causing dry skin and mydriasis) and myocardial fast sodium channels (causing wide QRS).

Analyze the fifth clinical presentation (yellow-tinted vision, atrial tachycardia with AV block).

Identify digoxin toxicity.

Digoxin inhibits the Na-K-ATPase pump, leading to characteristic visual changes and arrhythmias.

Select the specific pharmacologic antidote for each identified toxidrome.

Match opioids to naloxone, acetaminophen to N-acetylcysteine, beta-blockers to glucagon, TCAs to sodium bicarbonate, and digoxin to antibody fragments.

Specific antidotes target the distinct pathophysiologic mechanism of each toxin to rapidly reverse life-threatening manifestations.

Key Concept

Recognition of classic toxidromes and selection of specific, life-saving pharmacologic antidotes.

Question 17Question →

A medical resident is evaluating a 72-year-old man in the preoperative clinic prior to a scheduled open abdominal aortic aneurysm repair. The patient has a history of stroke, insulin-dependent diabetes mellitus, and chronic kidney disease. He is sedentary and unable to climb a flight of stairs due to lower extremity claudication. The attending physician asks the resident to outline the standardized stepwise approach for perioperative cardiovascular risk assessment according to the current clinical guidelines.

Arrange the following steps of the perioperative cardiovascular evaluation algorithm in their correct sequential order, from the absolute initial consideration to final preoperative decision-making.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential order for perioperative cardiovascular risk assessment is: 1) Determine surgical urgency, 2) Evaluate for active cardiac conditions, 3) Estimate perioperative clinical risk, 4) Quantify functional capacity, 5) Consider pharmacological stress testing.

The correct sequence mirrors the standardized American College of Cardiology/American Heart Association (ACC/AHA) algorithm for perioperative cardiovascular evaluation. This algorithm is strictly designed to be sequential in order to prevent unnecessary testing, avoid surgical delays, and systematically identify patients who are at a genuinely high risk for perioperative mortality.

Step-by-Step Solution

Determine the urgency of the surgical procedure.

Identifies true emergencies that bypass all preoperative testing.

Emergency surgeries cannot be delayed, making extensive cardiac workup futile and dangerous.

Assess for active or unstable cardiac conditions.

Screens for recent myocardial infarction, decompensated heart failure, or severe symptomatic arrhythmias.

These conditions carry prohibitively high surgical mortality and require immediate intervention prior to any elective procedure.

Estimate the combined clinical and procedural risk of major adverse cardiac events (MACE).

Calculates risk using tools like the Revised Cardiac Risk Index (RCRI).

If the MACE risk is low (<1%), no further testing is necessary and surgery can proceed.

Evaluate the patient's functional capacity in METs.

Determines if the patient can perform moderate-intensity activities (≥4 METs).

Excellent functional capacity overrides elevated clinical risk scores, allowing patients to proceed directly to surgery.

Consider pharmacological stress testing.

Provides objective ischemia data in sedentary or severely impaired patients.

Testing is strictly reserved for patients with elevated risk and poor functional capacity, provided the results will alter the surgical approach.

Key Concept

Perioperative Cardiovascular Evaluation Algorithm

Estimated Time:1m 30s

Question 18Question →

The nursing staff urgently requests an evaluation of a $64$ -year-old man in the pulmonary step-down unit due to decreasing responsiveness. The patient was admitted $36$ hours ago for a severe exacerbation of chronic obstructive pulmonary disease (COPD). His initial treatment included intravenous methylprednisolone, nebulized ipratropium-albuterol, oral doxycycline, and supplemental oxygen. Over the past $12$ hours, his oxygen delivery was escalated to a non-rebreather mask by the cross-cover team due to perceived hypoxemia. His other medical history includes systemic hypertension, diet-controlled type 2 diabetes, and osteoarthritis.

Vital signs are:
Temperature: $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ )
Blood pressure: $142/86 \text{ mm Hg}$
Heart rate: $108/\text{min}$
Respiratory rate: $8/\text{min}$
Pulse oximetry: $99\%$ on the non-rebreather mask

On physical examination, the patient is lethargic but opens his eyes and follows simple commands when spoken to loudly. Noticeable asterixis is present on bilateral wrist extension. The jugular venous pressure is visually estimated at $5 \text{ cm H}_2\text{O}$ . Auscultation of the chest reveals a markedly prolonged expiratory phase with faint, diffuse wheezing, but no crackles. The cardiac rhythm is regular. Trace bilateral pedal edema is noted.

Relevant morning laboratory panels show:
Leukocytes: $8,200/\text{mm}^3$
Sodium: $138 \text{ mEq/L}$
Potassium: $4.3 \text{ mEq/L}$
Chloride: $94 \text{ mEq/L}$
Bicarbonate: $36 \text{ mEq/L}$
Thyroid-stimulating hormone (TSH): $0.1 \mu\text{U/mL}$ (Normal: $0.4-4.0 \mu\text{U/mL}$ )
Free thyroxine (T4): $1.2 \text{ ng/dL}$ (Normal: $0.9-1.7 \text{ ng/dL}$ )

An arterial blood gas analysis drawn on his current oxygen support demonstrates:
pH: $7.20$
$PaCO_2$ : $95 \text{ mm Hg}$
$PaO_2$ : $148 \text{ mm Hg}$

Based on these clinical and laboratory findings, which of the following is the most appropriate next step in management?

Administer intravenous sodium bicarbonate to correct the severe acidemia

Discontinue doxycycline and initiate empiric intravenous vancomycin and cefepime

Transition to noninvasive positive-pressure ventilation and titrate oxygen to target a saturation of 88% to 92%

Administer intravenous furosemide and obtain an urgent echocardiogram

Administer intravenous levothyroxine for acute central hypothyroidism

Show answer & explanation

Answer: Transition to noninvasive positive-pressure ventilation and titrate oxygen to target a saturation of 88% to 92%

Answer

Transition to noninvasive positive-pressure ventilation and titrate oxygen to target a saturation of 88% to 92%

The correct answer involves treating the patient's oxygen-induced hypercapnia. Patients with severe COPD rely on hypoxic pulmonary vasoconstriction to optimize V/Q matching. Administering excessive high-flow oxygen (resulting in a

PaO_2

148 \text{ mm Hg}

) reverses this vasoconstriction, increasing dead space ventilation. Furthermore, high

O_2

levels decrease the affinity of hemoglobin for

CO_2

(Haldane effect), leading to a massive spike in

PaCO_2

(

95 \text{ mm Hg}

) and subsequent

CO_2

narcosis (evidenced by somnolence and asterixis). The appropriate management is to transition to noninvasive positive-pressure ventilation (to actively clear

CO_2

and support respiratory mechanics) and to strictly titrate oxygen delivery to a target saturation of

88\%-92\%

to prevent recurrent hypercapnia.

Step-by-Step Solution

Analyze the patient's arterial blood gas and physical exam to identify the primary pathophysiologic insult.

The ABG shows a severe acute-on-chronic respiratory acidosis (pH

7.20

PaCO_2

95 \text{ mm Hg}

) and hyperoxia (

PaO_2

148 \text{ mm Hg}

). The patient has classic signs of

CO_2

narcosis (somnolence, asterixis, hypoventilation).

Understanding the primary disturbance is required before selecting an intervention.

Correlate the findings with the recent management changes.

The escalation to a non-rebreather mask caused the hyperoxia, which abolished hypoxic pulmonary vasoconstriction, worsened V/Q mismatch, and led to the massive retention of

CO_2

Identifying the iatrogenic cause dictates the corrective action.

Evaluate the distractor presentations (cardiac, infectious, endocrine, metabolic).

The absence of crackles and normal JVP rules out heart failure. The lack of fever or leukocytosis rules out new sepsis. The TSH/T4 pattern represents medication-induced suppression (steroids), not hypothyroidism. The high bicarbonate represents chronic metabolic compensation for his baseline COPD, not an indication for sodium bicarbonate.

Systematically ruling out competing diagnoses prevents premature closure and selection of incorrect, harmful therapies.

Determine the most appropriate next step in management.

Remove the non-rebreather mask, apply noninvasive positive-pressure ventilation (NPPV) to assist with

CO_2

clearance, and titrate oxygen to target a safe saturation of

88\%-92\%

This directly treats both the iatrogenic cause and the life-threatening respiratory failure without resorting to premature intubation.

Key Concept

Diagnosis and management of oxygen-induced hypercapnia in chronic obstructive pulmonary disease

Question 19Question →

An internal medicine physician is urgently called to evaluate a 54-year-old male admitted overnight for observation. The nursing staff reports that the patient has developed new-onset confusion, a severe holocephalic headache, and photophobia over the last 4 hours. Vital signs show a temperature of $39.4^\circ\text{C}$ ( $102.9^\circ\text{F}$ ), pulse of $112/\text{min}$ , and blood pressure of $138/82\text{ mmHg}$ . Neurologic examination demonstrates a Glasgow Coma Scale score of 11, prominent resistance to passive neck flexion, and bilateral papilledema. No other focal neurologic deficits are present.

Arrange the following diagnostic and therapeutic steps in the most appropriate chronological sequence for this patient's management.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing suspected bacterial meningitis with elevated intracranial pressure signs is: 1) Obtain peripheral blood cultures, 2) Administer intravenous dexamethasone and empiric antibiotics, 3) Perform a non-contrast CT scan of the head, 4) Perform a lumbar puncture, and 5) Tailor antimicrobial therapy based on culture results.

The correct sequence prioritizes immediate life-saving interventions (blood cultures followed immediately by empiric antibiotics) before addressing diagnostic testing that could cause delays. Because this patient has red flags for increased intracranial pressure (papilledema, Glasgow Coma Scale of 11), a CT scan is mandatory before a lumbar puncture to avoid herniation. However, obtaining a CT scan takes time. Therefore, blood cultures are drawn immediately, followed by empiric antibiotics and dexamethasone. Once therapy is initiated, the CT scan is performed. If the CT is clear, the lumbar puncture follows. Finally, antibiotics are tailored based on the culture results.

Step-by-Step Solution

Identify the clinical syndrome and any high-risk features.

The patient has signs of acute bacterial meningitis (fever, headache, nuchal rigidity) complicated by 'red flags' for increased intracranial pressure (papilledema, Glasgow Coma Scale of 11).

Recognizing red flags (altered mental status, papilledema, focal deficits, seizures) is crucial because they mandate neuroimaging prior to a lumbar puncture.

Determine the priority of immediate life-saving interventions.

Blood cultures and empiric antibiotics must be prioritized above diagnostic imaging.

In acute bacterial meningitis, delays in antibiotic administration significantly increase mortality. Blood cultures take minutes and should be drawn first, followed immediately by empiric antibiotics.

Establish the order of diagnostic imaging and definitive testing.

CT scan of the head must precede the lumbar puncture.

Because the patient has signs of elevated intracranial pressure, a lumbar puncture could provoke fatal cerebral herniation. A CT scan is necessary to confirm the absence of significant mass effect.

Determine the final clinical follow-up step.

Tailoring of antibiotics based on culture data.

Once cultures return, the initial broad-spectrum empiric regimen is narrowed to targeted therapy for antimicrobial stewardship.

Key Concept

In patients with suspected bacterial meningitis who have indications for a CT scan prior to lumbar puncture (e.g., altered mental status, papilledema, focal deficits), empiric antibiotics and dexamethasone MUST be administered immediately after drawing blood cultures, without waiting for neuroimaging.

Estimated Time:1m 30s

Question 20Question →

A $60$ -year-old woman is brought to the emergency department by her husband due to progressive confusion, profound fatigue, and generalized weakness over the past week. Two weeks ago, she had a mild upper respiratory infection. Her husband notes she has been complaining of intermittent headaches and peripheral vision loss for the last three months. Her temperature is $36.2^\circ\text{C}$ ( $97.2^\circ\text{F}$ ), blood pressure is $82/50\text{ mm Hg}$ , pulse is $54/\text{min}$ , and respirations are $16/\text{min}$ . Physical examination shows a lethargic woman with dry, pale skin and delayed relaxation of deep tendon reflexes. Mild bilateral non-pitting lower extremity edema is present. Lung auscultation reveals decreased breath sounds at the bases but no crackles or wheezes.

Laboratory evaluation shows:

Parameter	Value
Sodium	$128\text{ mEq/L}$
Potassium	$4.2\text{ mEq/L}$
Chloride	$98\text{ mEq/L}$
Bicarbonate	$20\text{ mEq/L}$
Blood urea nitrogen	$24\text{ mg/dL}$
Creatinine	$1.1\text{ mg/dL}$
pH	$7.32$
$\text{PaCO}_2$	$38\text{ mm Hg}$
$\text{PaO}_2$	$85\text{ mm Hg}$
Thyroid-stimulating hormone (TSH)	$0.8\text{ \mu U/mL}$ (Normal: $0.4-4.0\text{ \mu U/mL}$ )
Free thyroxine ( $\text{T}_4$ )	$0.3\text{ ng/dL}$ (Normal: $0.9-1.7\text{ ng/dL}$ )

Which of the following is the most appropriate next step in the management of this patient?

Administration of intravenous hydrocortisone

Initiation of oral levothyroxine therapy

Administration of intravenous furosemide

Administration of intravenous broad-spectrum antibiotics

Administration of intravenous sodium bicarbonate

Show answer & explanation

Answer: Administration of intravenous hydrocortisone

Answer

Administration of intravenous hydrocortisone

This patient's presentation of headaches, peripheral vision loss, profound fatigue, bradycardia, and non-pitting edema is highly suspicious for a pituitary macroadenoma causing panhypopituitarism. The laboratory findings of a low free

\text{T}_4

coupled with an inappropriately normal TSH confirm central (secondary) hypothyroidism. The patient is currently presenting with hemodynamic collapse (hypotension, altered mental status) and hyponatremia, triggered by the physiological stress of a recent viral infection. This is the classic presentation of an acute adrenal crisis due to secondary adrenal insufficiency (ACTH deficiency). Notably, in secondary adrenal insufficiency, aldosterone production is preserved via the renin-angiotensin-aldosterone system, which is why her serum potassium level is normal despite the severe hyponatremia (caused by loss of cortisol's suppressive effect on ADH). In cases of suspected adrenal crisis, immediate administration of intravenous glucocorticoids (such as hydrocortisone) is life-saving and is the most critical next step. Glucocorticoids must always be replaced before thyroid hormone.

Step-by-Step Solution

Evaluate the clinical presentation for underlying etiology.

The combination of headaches, peripheral vision loss (bitemporal hemianopsia), and signs of hypothyroidism suggests a pituitary macroadenoma.

Mass effect from a pituitary tumor commonly compresses the optic chiasm and disrupts normal anterior pituitary hormone secretion.

Interpret the thyroid function tests.

The free

\text{T}_4

is low while the TSH is inappropriately normal, indicating central (secondary) hypothyroidism.

In primary hypothyroidism, the TSH would be significantly elevated. A normal or low TSH in the presence of low

\text{T}_4

implies pituitary or hypothalamic failure.

Analyze the acute hemodynamic collapse.

The patient is experiencing hypotension, altered mental status, and hyponatremia triggered by a recent infection, representing an acute adrenal crisis.

A pituitary mass causing central hypothyroidism likely also causes secondary adrenal insufficiency (ACTH deficiency), which decompensates under physiological stress.

Determine the safest and most critical initial treatment.

Intravenous hydrocortisone must be administered immediately.

Glucocorticoids must be replaced before thyroid hormone, because thyroid hormone increases the metabolic clearance of cortisol and can precipitate a fatal adrenal crisis if given alone.

Key Concept

In patients with suspected panhypopituitarism presenting in acute decompensation, immediate intravenous glucocorticoid replacement is required to treat secondary adrenal crisis before initiating thyroid hormone replacement.

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