Internal Medicine

3151 questions

All types3,151 Multiple choice1,611 Multiple select73 Numeric81 Matching714 Ordering672

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.

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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 42Question →

An obese 58-year-old male with a 5-year history of essential hypertension arrives at the urgent care center due to intense, throbbing pain in his left foot that began abruptly during the night. He reports that even the weight of his bedsheet on the foot causes excruciating discomfort. His vital signs are within normal limits. Examination reveals a markedly swollen, red, warm, and tender left first metatarsophalangeal joint. The overlying skin is tense but intact, with no evidence of puncture wounds or purulent drainage. Which of the following is the most appropriate next step in the management of this patient's acute symptoms?

Initiation of oral naproxen

Administration of broad-spectrum intravenous antibiotics

Measurement of serum uric acid level to confirm the diagnosis

Prescription of daily oral furosemide

Immediate computed tomography scan of the affected foot

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Answer: Initiation of oral naproxen

Answer

Initiation of oral naproxen is the most appropriate next step.

The patient presents with sudden, severe, monoarticular inflammation of the first metatarsophalangeal joint, which is a classic presentation of acute gout (podagra). First-line therapies for acute gout include nonsteroidal anti-inflammatory drugs (NSAIDs) such as naproxen or indomethacin, colchicine, or glucocorticoids. Because this patient has no apparent contraindications (e.g., advanced chronic kidney disease or active peptic ulcer disease), an NSAID is the most appropriate initial management to rapidly reduce inflammation and provide symptom relief.

Step-by-Step Solution

Analyze the patient's clinical presentation.

The patient has acute, severe monoarticular arthritis of the first metatarsophalangeal joint (podagra), highly suspicious for an acute gout flare.

Identifying the classic signs of gout is essential for clinical diagnosis.

Evaluate the need for diagnostic testing versus empiric treatment.

The classic presentation allows for immediate empiric treatment without waiting for joint aspiration, given the absence of fever or signs of systemic infection.

Prompt treatment relieves severe pain and limits the duration of the inflammatory response.

Select the most appropriate initial pharmacotherapy.

Oral naproxen is selected as the optimal first-line agent.

NSAIDs are highly effective for acute gout flares and are preferred in patients without significant renal impairment or active peptic ulcer disease.

Key Concept

The classic presentation of acute gouty arthritis (podagra) can often be diagnosed clinically. First-line management involves prompt initiation of a nonsteroidal anti-inflammatory drug (NSAID), colchicine, or a systemic glucocorticoid.

Question 43Question →

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

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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 44Question →

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.

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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 45Question →

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

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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 46Question →

A $65$ -year-old man with a history of a renal transplantation presents to the emergency department with a $1$ -day history of fever, severe headache, and confusion. His temperature is $39.2^\circ\text{C}$ ( $102.6^\circ\text{F}$ ), blood pressure is $110/70\text{ mm Hg}$ , and pulse is $115/\text{min}$ . Physical examination reveals nuchal rigidity and bilateral papilledema. He is suspected of having acute bacterial meningitis. Arrange the following diagnostic and therapeutic steps in the most appropriate sequential order for managing this patient.

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Answer

The correct sequence is: Obtain blood cultures, Administer empiric intravenous antibiotics and dexamethasone, Perform a non-contrast CT scan of the head, and Perform a lumbar puncture.

In the management of suspected bacterial meningitis, blood cultures must be drawn first to help identify the causative organism. Because this patient has 'red flags' (papilledema, altered mental status, and an immunocompromised state) that require a CT scan before a lumbar puncture to prevent cerebral herniation, empiric antibiotics must not be delayed while waiting for neuroimaging. Therefore, antibiotics are administered immediately after blood cultures are drawn, followed by the CT scan, and finally the lumbar puncture.

Step-by-Step Solution

Recognize the clinical presentation of suspected acute bacterial meningitis with high-risk features.

The patient has signs of meningitis (fever, headache, nuchal rigidity) along with red flags for increased intracranial pressure (papilledema, confusion) and an immunocompromised state (renal transplant).

Identifying these features determines the appropriate sequence of diagnostic and therapeutic interventions.

Determine the very first step in management.

Blood cultures should be obtained immediately.

Drawing blood cultures before administering antibiotics is crucial for isolating the pathogen without delaying treatment.

Determine the timing of empiric therapy.

Administer empiric intravenous antibiotics and dexamethasone immediately after drawing blood cultures.

Because a CT scan is required before a lumbar puncture, definitive CSF analysis will be delayed. Antibiotics must not be withheld during this delay, as mortality increases significantly.

Assess the need and timing for neuroimaging.

Perform a non-contrast CT scan of the head next.

Due to the patient's papilledema, confusion, and immunocompromised status, a CT scan is necessary to rule out mass effect before safely performing a lumbar puncture.

Determine the final step once neuroimaging is cleared.

Perform a lumbar puncture.

Once the CT scan confirms the absence of a mass lesion or midline shift, it is safe to proceed with the lumbar puncture to obtain CSF for analysis and culture.

Key Concept

In patients with suspected bacterial meningitis who have indications for a CT scan before lumbar puncture (e.g., papilledema, immunocompromised state, focal neurologic deficit, altered mental status), blood cultures must be drawn first, followed immediately by empiric antibiotics. The CT scan is then performed, followed by the lumbar puncture if considered safe.

Question 47Question →

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.

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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 48Question →

A $72$ -year-old woman is brought to the emergency department for sudden-onset severe shortness of breath, lightheadedness, and right-sided chest pain. She recently returned from a $12$ -hour international flight two days ago. Her medical history includes moderate chronic obstructive pulmonary disease (COPD) and hypertension.

On arrival, she is somnolent but arousable. Temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $82/50\text{ mm Hg}$ , pulse is $118/\text{min}$ , and respirations are $28/\text{min}$ . Oxygen saturation is $85\%$ on room air.

Physical examination reveals elevated jugular venous pressure. Lung auscultation is clear bilaterally.

Bedside transthoracic echocardiography demonstrates a severely enlarged right ventricle with hypokinesis of the free wall and normal apical contraction. The left ventricle is small and hyperdynamic.

An arterial blood gas on room air shows:
pH: $7.29$
$\text{PaCO}_2$ : $26\text{ mm Hg}$
$\text{PaO}_2$ : $54\text{ mm Hg}$
$\text{HCO}_3^-$ : $12\text{ mEq/L}$

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

Administration of systemic alteplase

Transport for computed tomography pulmonary angiography

Intravenous administration of furosemide

Intravenous administration of piperacillin-tazobactam

Endotracheal intubation and mechanical ventilation

Show answer & explanation

Answer: Administration of systemic alteplase

Answer

Administration of systemic alteplase

The correct answer is the administration of systemic alteplase. This patient presents with classic signs of a massive (high-risk) pulmonary embolism (PE): sudden-onset dyspnea, hypoxia, and hemodynamic instability (hypotension) following a major risk factor (prolonged travel). In patients with suspected massive PE who are too unstable to safely undergo definitive imaging (CT pulmonary angiography), bedside transthoracic echocardiography is the diagnostic test of choice. The presence of right ventricular dilation and free wall hypokinesis with apical sparing (McConnell's sign) provides sufficient evidence of acute right heart strain to justify immediate intervention. The treatment of choice for massive PE in the absence of absolute contraindications is systemic thrombolysis (e.g., alteplase). Thrombolytics rapidly lyse the clot, reducing pulmonary vascular resistance, alleviating right ventricular strain, and improving cardiac output.

Step-by-Step Solution

Identify the primary clinical syndrome.

The patient presents with sudden-onset dyspnea, hypoxia, right-sided chest pain, and profound hypotension (

82/50

mm Hg) following a period of prolonged immobilization.

Establishing the severity and likely etiology (massive pulmonary embolism causing cardiogenic shock).

Interpret the diagnostic data.

Bedside echocardiography shows right ventricular dilation and hypokinesis with apical sparing (McConnell's sign), confirming acute right heart strain. The ABG shows a primary metabolic acidosis (lactic acidosis from shock) with appropriate respiratory compensation.

To confirm the diagnosis of massive PE and safely rule out other causes of shock or acute respiratory failure.

Determine the most appropriate next step in management.

In a hemodynamically unstable patient with high clinical suspicion for PE and bedside echo evidence of RV strain, systemic thrombolysis (alteplase) is indicated immediately without waiting for definitive CT imaging.

To rapidly dissolve the thrombus, reduce right ventricular afterload, and restore cardiac output.

Key Concept

Massive (high-risk) pulmonary embolism is defined by hemodynamic instability (systolic BP

< 90

mm Hg) and should be managed with systemic thrombolytics if bedside echocardiography shows right heart strain, as these patients are often too unstable for CT pulmonary angiography.

Alternative Method

In advanced centers, catheter-directed thrombolysis or surgical pulmonary embolectomy may be considered as alternative emergent treatments for massive PE, particularly if systemic thrombolysis has failed or is absolutely contraindicated.

Estimated Time:1m 30s

Question 49Question →

A 32-year-old woman is brought to the emergency department by her partner due to 5 days of severe, voluminous diarrhea and abdominal cramping. She has a history of ulcerative colitis and panic disorder. In the waiting room, she experienced a severe panic attack and was noted to have visibly rapid, deep breathing. Physical examination reveals dry mucous membranes, decreased skin turgor, a heart rate of $115/\text{min}$ , a respiratory rate of $28/\text{min}$ , and a blood pressure of $105/65\text{ mm Hg}$ .

Laboratory results are as follows:

Laboratory Test	Result	Reference Range
Sodium	$136 \text{ mEq/L}$	$136-145 \text{ mEq/L}$
Potassium	$3.2 \text{ mEq/L}$	$3.5-5.0 \text{ mEq/L}$
Chloride	$115 \text{ mEq/L}$	$95-105 \text{ mEq/L}$
Bicarbonate	$12 \text{ mEq/L}$	$22-28 \text{ mEq/L}$
Blood urea nitrogen	$34 \text{ mg/dL}$	$7-18 \text{ mg/dL}$
Creatinine	$1.2 \text{ mg/dL}$	$0.6-1.2 \text{ mg/dL}$

Arterial blood gas (room air):

Arterial Blood Gas	Result	Reference Range
pH	$7.40$	$7.35-7.45$
$\text{pCO}_2$	$20 \text{ mm Hg}$	$35-45 \text{ mm Hg}$
$\text{pO}_2$	$98 \text{ mm Hg}$	$80-100 \text{ mm Hg}$

Which of the following best describes this patient's acid-base status?

Mixed normal anion gap metabolic acidosis and respiratory alkalosis

Compensated normal anion gap metabolic acidosis

Mixed normal anion gap metabolic acidosis and respiratory acidosis

Mixed high anion gap metabolic acidosis and respiratory alkalosis

Compensated high anion gap metabolic acidosis

Show answer & explanation

Answer: Mixed normal anion gap metabolic acidosis and respiratory alkalosis

Answer

Mixed normal anion gap metabolic acidosis and respiratory alkalosis

The patient's initial insult is severe diarrhea, which causes profound gastrointestinal loss of bicarbonate, resulting in a normal anion gap metabolic acidosis (NAGMA). This is confirmed by an anion gap of

9 \text{ mEq/L}

(

136 - 115 - 12 = 9

). To evaluate if respiratory compensation is appropriate, Winter's formula is applied:

\text{Expected pCO}_2 = (1.5 \times 12) + 8 \pm 2 = 26 \pm 2 \text{ mm Hg}

. Because the patient's actual

\text{pCO}_2

(

20 \text{ mm Hg}

) is significantly lower than the expected range (

24-28 \text{ mm Hg}

), she is 'blowing off' more

\text{CO}_2

than expected. This indicates a coexisting primary respiratory alkalosis, clinically correlating with her panic attack and hyperventilation in the waiting room. The two opposing disorders (acidosis and alkalosis) offset each other, resulting in a seemingly normal pH of

7.40

Step-by-Step Solution

Calculate the anion gap to identify the primary metabolic disturbance.

\text{Anion Gap} = \text{Na}^+ - (\text{Cl}^- + \text{HCO}_3^-) = 136 - (115 + 12) = 9 \text{ mEq/L}

Since the anion gap is within the normal range (

8-12 \text{ mEq/L}

), the patient has a normal anion gap metabolic acidosis (NAGMA), consistent with bicarbonate loss from severe diarrhea.

Apply Winter's formula to determine the expected respiratory compensation.

\text{Expected pCO}_2 = 1.5 \times [\text{HCO}_3^-] + 8 \pm 2 = (1.5 \times 12) + 8 \pm 2 = 26 \pm 2 \text{ mm Hg}

. The expected range is

24-28 \text{ mm Hg}

Winter's formula determines if the lungs are appropriately compensating for a metabolic acidosis by decreasing

\text{pCO}_2

Compare the actual measured

\text{pCO}_2

with the expected

\text{pCO}_2

range.

The patient's actual

\text{pCO}_2

20 \text{ mm Hg}

, which is lower than the expected range of

24-28 \text{ mm Hg}

Because the

\text{pCO}_2

is lower than what pure metabolic compensation would dictate, there is an additional process driving CO2 down—a primary respiratory alkalosis (due to hyperventilation from her panic attack).

Key Concept

In patients with metabolic acidosis, Winter's formula (

1.5 \times [\text{HCO}_3^-] + 8 \pm 2

) must be used to calculate expected

\text{pCO}_2

. An actual

\text{pCO}_2

lower than the expected range indicates a superimposed primary respiratory alkalosis.

Question 50Question →

A 58-year-old man collapses in the hospital lobby. A nearby physician confirms he is unresponsive, apneic, and lacks a palpable carotid pulse. A resuscitation team arrives immediately with a crash cart, and the initial cardiac monitor displays coarse ventricular fibrillation. Arrange the following interventions in the correct chronological sequence according to standard Advanced Cardiac Life Support (ACLS) guidelines for adult cardiac arrest.

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Answer

The correct sequence for managing ventricular fibrillation is to first initiate CPR and attach the defibrillator, then deliver an immediate shock, followed immediately by 2 minutes of CPR while obtaining IV/IO access, and finally performing a rhythm check with subsequent epinephrine administration if the rhythm remains shockable.

The Advanced Cardiac Life Support algorithm dictates a strict sequence to maximize survival in shockable cardiac arrests (ventricular fibrillation and pulseless ventricular tachycardia). The sequence must begin with high-quality CPR and defibrillator attachment. Once a shockable rhythm is confirmed, the immediate next step is a single unsynchronized shock. Following the shock, providers must immediately resume CPR for 2 minutes without pausing for a rhythm check, during which time intravenous or intraosseous access should be established. Only after these 2 minutes of CPR is another rhythm check performed; if the rhythm remains shockable, another shock is delivered, followed by the administration of 1 mg of epinephrine.

Step-by-Step Solution

Recognize cardiac arrest and prepare for intervention.

CPR is initiated and the monitor is attached to identify the rhythm.

Minimizing time without perfusion is critical. The defibrillator must be attached to determine if the rhythm is shockable.

Treat the primary shockable rhythm.

An unsynchronized shock is delivered.

Ventricular fibrillation requires immediate electrical therapy to depolarize the myocardium and allow a normal pacemaker to resume.

Provide post-shock perfusion and prepare for medical therapy.

High-quality compressions are resumed for 2 minutes while IV or IO access is secured.

Compressions immediately after a shock are necessary because the heart rarely generates effective perfusion immediately after defibrillation. Pausing for a pulse check is contraindicated.

Evaluate rhythm and escalate therapy.

A rhythm check is performed, a second shock is delivered if appropriate, and epinephrine is given.

Epinephrine is indicated after the initial shock and subsequent 2-minute CPR cycle if the rhythm remains in ventricular fibrillation or pulseless ventricular tachycardia.

Key Concept

Advanced Cardiac Life Support (ACLS) Ventricular Fibrillation Algorithm

Estimated Time:1m 0s

Question 51Question →

A $31$ -year-old woman, G $1$ P $0$ at $34$ weeks gestation, is brought to the emergency department after being involved in a high-speed motor vehicle collision. She complains of anterior chest pain and severe shortness of breath. Her blood pressure is $78/48$ mm Hg, heart rate is $135$ bpm, and respiratory rate is $26$ /min. Pulse oximetry shows $93\%$ on room air. Physical examination reveals distended jugular veins and distant, muffled heart sounds. Breath sounds are equal bilaterally, but faint scattered wheezes are auscultated. The trachea is midline. Bedside focused assessment with sonography for trauma (FAST) demonstrates a large anechoic space surrounding the heart with right ventricular free wall inversion during diastole. There is no evidence of intraperitoneal fluid. Continuous fetal heart rate monitoring shows a baseline of $140$ bpm with moderate variability and no decelerations. Which of the following is the most appropriate next step in management for this patient?

Immediate echocardiography-guided pericardiocentesis

Transfer to the radiology suite for a computed tomography scan of the chest

Administration of inhaled bronchodilators and systemic corticosteroids

Continued observation and reassurance regarding expected hemodynamic changes

Preparation for an immediate emergent cesarean delivery

Show answer & explanation

Answer: Immediate echocardiography-guided pericardiocentesis

Answer

Immediate echocardiography-guided pericardiocentesis

The correct option is immediate pericardiocentesis because the patient presents with classic signs of cardiac tamponade (Beck's triad) leading to obstructive shock following blunt chest trauma. The FAST exam confirms a large pericardial effusion with right ventricular diastolic collapse. In a hemodynamically unstable patient, the immediate life-saving intervention is bedside pericardiocentesis to relieve intrapericardial pressure, allowing the right ventricle to fill during diastole and restoring cardiac output. Pregnancy does not change the fundamental algorithm for treating life-threatening obstructive shock.

Step-by-Step Solution

Identify the primary diagnosis based on the clinical presentation and ultrasound findings.

The patient has Beck's triad (hypotension, jugular venous distension, muffled heart sounds) and sonographic evidence of right ventricular diastolic collapse, confirming cardiac tamponade.

Accurate diagnosis is required before choosing an intervention in a trauma patient.

Assess the patient's hemodynamic status.

The patient is severely hypotensive and tachycardic, indicating obstructive shock.

Hemodynamic instability dictates the urgency of the management plan.

Determine the most appropriate immediate management.

Emergent pericardiocentesis is required.

Removing the pericardial fluid relieves the pressure on the heart, restoring venous return and cardiac output, regardless of pregnancy status.

Key Concept

Cardiac tamponade causes obstructive shock by impairing right ventricular filling; hemodynamically unstable patients require immediate pericardiocentesis to relieve intrapericardial pressure.

Estimated Time:1m 30s

Question 52Question →

An established clinic patient, who is 68 years old, presents for evaluation of bilateral leg swelling that has gradually worsened over the past 3 months. He additionally notes new-onset abdominal fullness and becoming breathless after walking short distances. The patient is oxygen-dependent due to a long-standing history of severe chronic obstructive pulmonary disease (COPD) and has previously smoked heavily for four decades. His temperature is 37.0°C (98.6°F), blood pressure is 135/85 mm Hg, and pulse is 88/min. Physical examination reveals markedly distended jugular veins, a palpable parasternal heave, and 3+ pitting edema of the lower extremities bilaterally. Cardiac auscultation reveals a holosystolic murmur at the left lower sternal border that increases in intensity with inspiration. Breath sounds are decreased bilaterally with a prolonged expiratory phase, but no crackles are heard. Which of the following is the most likely primary mechanism for this patient's current presentation?

Elevated pulmonary arterial pressure

Decreased left ventricular ejection fraction

Abnormal retrograde flow across the mitral valve

Impaired right ventricular filling due to pericardial thickening

Obstruction of the superior vena cava

Show answer & explanation

Answer: Elevated pulmonary arterial pressure

Answer

Elevated pulmonary arterial pressure

This patient's presentation is classic for cor pulmonale, which is defined as right ventricular hypertrophy and eventually right heart failure due to primary pulmonary disease. In patients with severe COPD, chronic alveolar hypoxia triggers hypoxic pulmonary vasoconstriction. Over time, this diffuse vasoconstriction leads to structural remodeling of the pulmonary vasculature and elevated pulmonary arterial pressure (pulmonary hypertension). The right ventricle must pump against this increased afterload, leading to right ventricular hypertrophy (evidenced by the palpable parasternal heave) and eventual right ventricular failure. This failure causes systemic venous congestion, manifesting as jugular venous distention, hepatic congestion (abdominal fullness), and significant peripheral edema. The dilation of the right ventricle also stretches the tricuspid valve annulus, causing functional tricuspid regurgitation (a holosystolic murmur at the left lower sternal border that increases in intensity during inspiration).

Step-by-Step Solution

Analyze the patient's history and risk factors.

The patient has severe, oxygen-dependent COPD.

Identifying the underlying chronic disease helps point toward its systemic complications.

Interpret the physical examination findings.

JVD, parasternal heave, lower extremity edema, and a murmur of tricuspid regurgitation (increases with inspiration) are present without pulmonary crackles.

These findings specifically indicate isolated right ventricular hypertrophy and right-sided heart failure.

Synthesize history and exam to determine the mechanism.

The combination of severe lung disease and right heart failure is diagnostic of cor pulmonale, which is driven by pulmonary hypertension.

Chronic hypoxia induces pulmonary vasoconstriction, leading to elevated pulmonary arterial pressure that overwhelms the right ventricle.

Key Concept

Cor Pulmonale

Estimated Time:1m 0s

Question 53Question →

Match each clinical presentation and characteristic physical examination finding with the most likely underlying valvular pathology.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The mid-systolic click with Valsalva accentuation matches mitral valve prolapse; the delayed carotid upstroke with a harsh systolic murmur matches aortic valve stenosis; the bounding pulse with an early diastolic murmur matches aortic valve regurgitation; and the loud S1 with a mid-diastolic rumble matches mitral valve stenosis.

Each clinical vignette presents a pathognomonic set of physical exam findings for a specific valvular lesion. A mid-systolic click with a late systolic murmur that worsens with decreased preload points to mitral valve prolapse. A delayed carotid upstroke with a harsh right-sided systolic murmur indicates aortic valve stenosis. Bounding pulses with an early diastolic murmur reveal aortic valve regurgitation. A loud S1 with a mid-diastolic rumbling murmur is characteristic of mitral valve stenosis.

Step-by-Step Solution

Analyze the young woman's presentation of a click and late systolic murmur.

Identified the murmur as mitral valve prolapse.

Valsalva decreases preload, which worsens the prolapse of redundant mitral valve leaflets, causing the murmur to appear earlier and become louder.

Analyze the elderly man's presentation of syncope and delayed carotid upstroke.

Identified the murmur as aortic valve stenosis.

The classic triad of symptoms (syncope, angina, dyspnea) along with pulsus parvus et tardus indicates fixed left ventricular outflow tract obstruction.

Analyze the middle-aged man's presentation of bounding pulses and head bobbing.

Identified the murmur as aortic valve regurgitation.

These peripheral signs indicate a hyperdynamic circulation and widened pulse pressure resulting from the rapid runoff of blood back into the left ventricle during diastole.

Analyze the young woman's presentation of hemoptysis and a diastolic rumble.

Identified the murmur as mitral valve stenosis.

This auscultatory profile, combined with signs of elevated pulmonary venous pressure (hemoptysis), strongly points to an obstructed mitral orifice, often rheumatic in origin.

Key Concept

Valvular Heart Disease Physical Examination Findings

Question 54Question →

A 72-year-old woman is brought to the emergency department at 3:00 AM due to the sudden onset of severe shortness of breath and wheezing that awoke her from sleep. She has a history of essential hypertension, type 2 diabetes mellitus, and a 35-pack-year smoking history. Current medications include amlodipine and metformin. Her blood pressure is 170/95 mm Hg, pulse is 92/min, and respirations are 24/min. Pulse oximetry shows 90% on room air. Physical examination reveals diffuse bilateral expiratory wheezing and a prolonged expiratory phase. Jugular venous pulsation is estimated at 9 cm H₂O. Cardiac auscultation reveals a regular rate and rhythm with a prominent S4 gallop; no murmurs are appreciated. Trace bilateral lower extremity edema is present. An electrocardiogram shows normal sinus rhythm with voltage criteria for left ventricular hypertrophy. A chest radiograph reveals a slightly enlarged cardiac silhouette but no focal consolidation or pleural effusion. The patient is administered continuous nebulized albuterol and intravenous methylprednisolone for a presumed chronic obstructive pulmonary disease exacerbation. One hour later, her dyspnea acutely worsens. Repeat vital signs show a blood pressure of 120/70 mm Hg and a pulse of 128/min. Repeat lung auscultation now reveals prominent bibasilar crackles extending to the mid-lung fields. Which of the following pathophysiologic mechanisms best explains this patient's acute clinical deterioration?

Decreased duration of ventricular diastole impairing myocardial filling

Dynamic hyperinflation leading to impaired venous return to the right atrium

Acute right ventricular failure secondary to hypoxic pulmonary vasoconstriction

Progressive small airway inflammation and mucus plugging

Beta-2 receptor mediated systemic vasodilation causing relative hypovolemia

Show answer & explanation

Answer: Decreased duration of ventricular diastole impairing myocardial filling

Answer

Decreased duration of ventricular diastole impairing myocardial filling

The patient initially presented with cardiac asthma (bronchospasm secondary to interstitial pulmonary congestion) due to heart failure with preserved ejection fraction (HFpEF). This underlying diagnosis is evidenced by her paroxysmal nocturnal dyspnea, S4 gallop, left ventricular hypertrophy, and elevated JVP. She was misdiagnosed with a COPD exacerbation and treated with albuterol. Albuterol, a beta-agonist, induced significant tachycardia (pulse rose to 128/min). In a patient with a stiff, hypertrophied ventricle, filling is heavily dependent on the duration of diastole. Tachycardia drastically shortens diastolic filling time, leading to a rapid rise in left atrial pressure. This backward pressure causes acute hydrostatic alveolar edema, manifesting as new bibasilar crackles, while the impaired forward stroke volume causes a drop in blood pressure.

Step-by-Step Solution

Analyze the initial presentation and recognize the misdiagnosis.

The patient presented with wheezing waking her from sleep (paroxysmal nocturnal dyspnea), elevated JVP, LVH, and an S4 gallop, which strongly indicates 'cardiac asthma' due to acute decompensated heart failure with preserved ejection fraction (HFpEF), not a primary COPD exacerbation.

Differentiating cardiac asthma from a true COPD exacerbation is critical, as therapies for one can be detrimental to the other.

Evaluate the physiologic effect of the administered intervention.

The patient was given high-dose nebulized albuterol, a beta-agonist that commonly causes reflex tachycardia or direct chronotropic effects due to beta-1 cross-reactivity, raising her heart rate from 92/min to 128/min.

Understanding the systemic side effects of respiratory medications is necessary to explain the clinical change.

Synthesize the hemodynamic consequences of the altered vital signs on the underlying pathology.

In a patient with a stiff, non-compliant left ventricle (S4 gallop, LVH), cardiac output and pulmonary pressures are highly dependent on adequate diastolic filling time.

Diastolic dysfunction requires longer filling times. Tachycardia drastically shortens diastole.

Connect the pathophysiology to the new physical exam findings.

The shortened diastole leads to a rapid backward accumulation of pressure into the left atrium and pulmonary veins, precipitating acute hydrostatic pulmonary edema, which manifests clinically as a drop in stroke volume (hypotension) and new bibasilar crackles.

This fully explains both the drop in blood pressure and the transition from wheezing (interstitial edema) to crackles (alveolar edema).

Key Concept

Patients with heart failure with preserved ejection fraction (HFpEF) are highly dependent on adequate diastolic filling time; tachycardia (e.g., from inappropriate albuterol use) shortens diastole, leading to acute left atrial hypertension and flash pulmonary edema.

Estimated Time:2m 0s

Question 55Question →

Match each patient's clinical presentation and laboratory profile to the most likely underlying pathophysiologic mechanism.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The clinical vignettes represent distinct mechanisms of calcium and phosphorus dysregulation: Humoral hypercalcemia of malignancy (PTHrP), Primary hyperparathyroidism (PTH overproduction), Familial hypocalciuric hypercalcemia (calcium-sensing receptor mutation), Sarcoidosis (ectopic 1-alpha-hydroxylase), and Osteomalacia (Vitamin D deficiency).

Correct matching requires evaluating serum calcium alongside serum phosphorus, intact PTH levels, and key clinical contextual clues to determine whether the metabolic abnormality is PTH-driven, PTH-independent, or a result of a defective receptor set-point.

Step-by-Step Solution

Analyze patient 1's profile

High calcium, low phosphorus, low PTH, central lung mass.

Identifies PTH-independent hypercalcemia due to malignancy (PTHrP secretion mimicking PTH effects).

Analyze patient 2's profile

High calcium, low phosphorus, high PTH, kidney stones.

Identifies PTH-dependent hypercalcemia caused by primary hyperparathyroidism.

Analyze patient 3's profile

High calcium, normal PTH, highly restricted urine calcium.

Identifies an altered calcium sensing set point indicative of Familial Hypocalciuric Hypercalcemia (FHH).

Analyze patient 4's profile

High calcium, high-normal phosphorus, low PTH, signs of sarcoidosis.

Identifies 1,25-dihydroxyvitamin D-mediated hypercalcemia from granulomatous macrophage activity.

Analyze patient 5's profile

Low calcium, low phosphorus, very high PTH, high alkaline phosphatase.

Identifies secondary hyperparathyroidism in response to severe Vitamin D deficiency causing osteomalacia.

Key Concept

Differential diagnosis of calcium and bone metabolism disorders using paired serum calcium, phosphorus, and parathyroid hormone levels.

Question 56Question →

A 58-year-old individual undergoing maintenance hemodialysis is admitted to the hospital due to progressive shortness of breath, orthopnea, and generalized fatigue over the past month. The patient has a history of type 2 diabetes mellitus and underwent creation of a left brachiocephalic arteriovenous fistula six months ago. Current medications include sevelamer, amlodipine, and erythropoietin. Vital signs reveal a blood pressure of $165/55$ mmHg, a pulse of $110$ /min with bounding peripheral pulses, and a respiratory rate of $22$ /min. Oxygen saturation is $93\%$ on ambient air. Physical examination demonstrates distended jugular veins up to $9$ cm $H_2O$ . Auscultation of the lungs reveals bilateral basilar crackles and scattered expiratory wheezes. Cardiac examination shows a hyperdynamic precordium, a soft systolic ejection murmur at the left upper sternal border, and an audible S3 gallop. The left arm exhibits a very prominent thrill and a continuous bruit over the access site. Echocardiography demonstrates a left ventricular ejection fraction of $68\%$ , biatrial enlargement, and a dilated left ventricle. Which of the following best describes the primary underlying hemodynamic derangement responsible for this patient's current symptoms?

Bypass of capillary beds resulting in decreased systemic vascular resistance

Bronchial smooth muscle spasm and mucosal inflammation

Accumulation of unmeasured endogenous organic acids

Primary reduction in myocardial contractility and forward flow

Bacterial vegetation formation on the atrioventricular valves

Show answer & explanation

Answer: Bypass of capillary beds resulting in decreased systemic vascular resistance

Answer

The condition is driven by the bypass of capillary beds resulting in decreased systemic vascular resistance.

The correct answer accurately describes the pathophysiology of high-output heart failure caused by a surgically created arteriovenous (AV) fistula. An AV fistula creates a direct connection between the high-pressure arterial system and the low-pressure venous system. This large shunt completely bypasses the systemic capillary beds, which normally provide the bulk of systemic vascular resistance (SVR). The sudden and sustained drop in SVR leads to a massive increase in venous return to the right heart. To maintain adequate perfusion pressure, the heart must dramatically increase its cardiac output by increasing both stroke volume (leading to a wide pulse pressure and bounding pulses) and heart rate. Over time, the chronic volume overload causes the ventricles to dilate, ultimately leading to decompensation and symptomatic high-output heart failure, presenting with pulmonary edema (crackles, 'cardiac asthma' wheezing) and elevated filling pressures (JVD, S3 gallop).

Step-by-Step Solution

Analyze the physical exam findings and vital signs.

The patient exhibits signs of volume overload and left heart failure (crackles, orthopnea, S3 gallop, JVD) alongside signs of a hyperdynamic state (bounding pulses, wide pulse pressure, tachycardia).

Identifying both the heart failure syndrome and the hyperdynamic circulation narrows the differential to high-output states.

Evaluate the echocardiogram data.

The ejection fraction is normal to high (

68\%

), ruling out standard left ventricular systolic dysfunction (HFrEF).

This confirms that the heart is contracting well and pumping a large volume of blood, rather than failing to eject.

Connect the clinical picture to the patient's medical history.

The patient has a large left brachiocephalic arteriovenous (AV) fistula with a very prominent thrill.

A large AV fistula acts as a massive left-to-right shunt, bypassing the high-resistance systemic arterioles. This drastically drops systemic vascular resistance, leading to increased venous return, which forces the heart to increase its stroke volume and heart rate, eventually resulting in high-output heart failure.

Key Concept

High-Output Heart Failure secondary to Arteriovenous Fistula

Question 57Question →

A 68-year-old man presents to the urgent care clinic with a 2-day history of progressively worsening shortness of breath and cough. He states that he is having to work much harder to breathe than usual. His past medical history is significant for a myocardial infarction 3 years ago and chronic obstructive pulmonary disease (COPD) managed with an inhaled long-acting bronchodilator. He has a 40-pack-year smoking history. Temperature is 37.0°C (98.6°F), blood pressure is 152/90 mmHg, pulse is 108/min, and respiratory rate is 26/min. Oxygen saturation is 89% on room air. Lung auscultation reveals diffuse expiratory wheezes and scattered basilar crackles. Cardiac examination is difficult to hear clearly due to loud breath sounds, and the neck veins are not easily visible due to his body habitus. Which of the following is the most appropriate next diagnostic test to determine whether his symptoms are primarily due to acute decompensated heart failure rather than a COPD exacerbation?

Serum B-type natriuretic peptide

Arterial blood gas analysis

Pulmonary function testing

Sputum Gram stain and culture

D-dimer assay

Show answer & explanation

Answer: Serum B-type natriuretic peptide

Answer

Serum B-type natriuretic peptide

The correct answer is serum B-type natriuretic peptide (BNP). This patient presents with acute dyspnea and wheezing in the setting of both a smoking history (COPD) and coronary artery disease (prior myocardial infarction). Wheezing can be a classic sign of a COPD exacerbation, but it can also occur in acute decompensated heart failure ('cardiac asthma') due to peribronchial fluid accumulation. Because his physical exam is non-diagnostic for volume overload (obscured JVP, no clear S3), a serum BNP level is the most useful next step. BNP is released from ventricular myocytes in response to increased wall tension. A normal BNP has a very high negative predictive value for ruling out heart failure, whereas a significantly elevated level supports a cardiac etiology for the dyspnea.

Step-by-Step Solution

Identify the patient's overlapping clinical features and risk factors.

The patient has dyspnea, wheezing, and hypoxemia with a history of both structural heart disease (prior myocardial infarction) and chronic lung disease (COPD).

Recognizing that 'cardiac asthma' (wheezing due to heart failure) mimics a COPD exacerbation is essential for determining the diagnostic approach.

Determine the limitation of the physical examination.

The physical exam cannot definitively confirm fluid overload (JVP is obscured) or rule out heart failure due to loud respiratory sounds.

When clinical signs are ambiguous, an objective biomarker is needed to differentiate the two conditions.

Select the most specific diagnostic test to distinguish heart failure from pulmonary disease.

Serum B-type natriuretic peptide (BNP) is selected.

BNP is released by ventricular myocytes under stretch; normal levels highly rule out acute decompensated heart failure, pointing toward COPD, while significantly elevated levels point toward heart failure.

Key Concept

B-type natriuretic peptide (BNP) is the most helpful laboratory test for differentiating between acute decompensated heart failure and a COPD exacerbation in patients presenting with undifferentiated dyspnea and wheezing.

Estimated Time:1m 0s

Question 58Question →

A 24-year-old woman with type 1 diabetes mellitus presents to the emergency department with abdominal pain, nausea, vomiting, and deep, rapid breathing. Vital signs show a heart rate of $118\text{ /min}$ and blood pressure of $90/60\text{ mmHg}$ . Laboratory studies show a blood glucose of $480 \text{ mg/dL}$ , an arterial pH of 7.15, positive serum ketones, and a serum potassium of $4.8 \text{ mEq/L}$ . Arrange the following management steps in the most appropriate chronological sequence for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Administer an initial bolus of 0.9% normal saline, 2) Initiate continuous intravenous regular insulin infusion, 3) Add 5% dextrose to the intravenous maintenance fluids, 4) Transition to subcutaneous basal and bolus insulin.

The standard protocol for Diabetic Ketoacidosis (DKA) management requires a strict sequence of interventions based on patient safety and pathophysiology. The absolute first priority is intravascular volume repletion with 0.9% normal saline because patients are severely dehydrated from osmotic diuresis. Once volume expansion has begun and serum potassium is confirmed to be safely elevated (> 3.3 mEq/L), an intravenous regular insulin infusion is started to stop lipolysis and ketogenesis. As the insulin works, blood glucose typically drops faster than the ketoacidosis resolves. To prevent hypoglycemia while continuing the insulin necessary to close the anion gap, 5% dextrose is added to the IV fluids once the blood glucose reaches approximately 200 to 250 mg/dL. Finally, after the anion gap is closed, the acidosis has resolved, and the patient can eat, they are safely transitioned to a subcutaneous insulin regimen.

Step-by-Step Solution

Recognize the diagnosis of diabetic ketoacidosis (DKA) and the immediate need for volume expansion.

Identify 0.9% normal saline bolus as the priority first step.

Patients with DKA are profoundly dehydrated due to osmotic diuresis, and restoring intravascular volume takes precedence over all other interventions.

Evaluate the serum potassium level to determine the safety of insulin therapy.

Identify that since potassium is 4.8 mEq/L, an intravenous insulin infusion can be started safely.

Insulin drives potassium into cells. Starting insulin without checking potassium (or if K+ < 3.3 mEq/L) can cause fatal hypokalemia. With a normal level, insulin is the immediate next step.

Determine the management approach for when blood glucose improves but the anion gap remains open.

Identify adding 5% dextrose to IV fluids as the subsequent step.

Glucose usually normalizes faster than the anion gap closes. Dextrose prevents hypoglycemia while allowing the insulin infusion to continue suppressing ketogenesis.

Identify the criteria for transitioning off the insulin infusion.

Select transitioning to subcutaneous insulin as the final step.

Once the anion gap closes (DKA resolved) and the patient can eat, they are transitioned to a standard subcutaneous insulin regimen.

Key Concept

The standard sequence of treatment for Diabetic Ketoacidosis (DKA) prioritizes aggressive volume resuscitation, followed by intravenous insulin (dependent on safe potassium levels), adding dextrose when glucose reaches 200 mg/dL, and finally transitioning to subcutaneous insulin upon resolution.

Estimated Time:1m 0s

Question 59Question →

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 60Question →

An emergency medical services team brings a $62$ -year-old man to the hospital following $4$ days of profuse, nonbloody diarrhea. His past medical history is significant for severe chronic obstructive pulmonary disease (COPD) managed with a daily inhaled tiotropium. Upon arrival, he reports profound fatigue and lightheadedness.

Vital signs include a heart rate of $108/\text{min}$ , blood pressure of $105/65\text{ mm Hg}$ , respiratory rate of $24/\text{min}$ , and temperature of $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ). Physical examination reveals dry oral mucosa and diminished skin turgor. The lungs have diffuse expiratory wheezes bilaterally.

Initial laboratory investigations reveal the following:

Laboratory Test	Result
Sodium	$138\text{ mEq/L}$
Potassium	$3.4\text{ mEq/L}$
Chloride	$111\text{ mEq/L}$
Bicarbonate	$14\text{ mEq/L}$
Blood urea nitrogen	$32\text{ mg/dL}$
Creatinine	$1.4\text{ mg/dL}$

Arterial blood gas (on room air):

Arterial Blood Gas	Result
pH	$7.22$
$\text{pCO}_2$	$36\text{ mm Hg}$
$\text{pO}_2$	$62\text{ mm Hg}$

Based on the laboratory results, which of the following is the most accurate characterization of this patient's acid-base status?

Mixed metabolic acidosis and respiratory acidosis

Metabolic acidosis with appropriate respiratory compensation

Mixed metabolic acidosis and respiratory alkalosis

Primary respiratory acidosis with appropriate metabolic compensation

Uncompensated metabolic acidosis

Show answer & explanation

Answer: Mixed metabolic acidosis and respiratory acidosis

Answer

Mixed metabolic acidosis and respiratory acidosis

This patient has a low pH (

7.22

) and a low serum bicarbonate (

14\text{ mEq/L}

), which establishes the presence of a primary metabolic acidosis (non-anion gap, given the gap of

13

, which is consistent with severe diarrhea). To determine if the respiratory compensation is appropriate, Winter's formula must be applied: Expected

\text{pCO}_2 = (1.5 \times \text{HCO}_3^-) + 8 \pm 2

. For this patient, the expected

\text{pCO}_2

(1.5 \times 14) + 8 = 21 + 8 = 29 \pm 2

(range:

27-31\text{ mm Hg}

). The patient's actual

\text{pCO}_2

36\text{ mm Hg}

. Because the actual

\text{pCO}_2

is greater than the expected range, there is a concomitant primary respiratory acidosis. This is a common finding in patients with advanced COPD who cannot adequately increase their minute ventilation in response to acidemia.

Step-by-Step Solution

Identify the primary acid-base disorder by evaluating the pH and serum bicarbonate.

The pH is

7.22

(acidemia) and the bicarbonate is

14\text{ mEq/L}

(low). This indicates a primary metabolic acidosis.

The pH determines the primary direction of the derangement, and the concordant change in bicarbonate confirms a metabolic etiology.

Calculate the expected

\text{pCO}_2

using Winter's formula to assess for mixed disorders.

Expected

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

(range

27-31\text{ mm Hg}

Winter's formula determines if the respiratory response (hyperventilation) to a metabolic acidosis is appropriate.

Compare the actual

\text{pCO}_2

to the expected

\text{pCO}_2

The actual

\text{pCO}_2

(

36\text{ mm Hg}

) is higher than the expected range (

27-31\text{ mm Hg}

A higher-than-expected

\text{pCO}_2

indicates inadequate ventilation, meaning a superimposed respiratory acidosis is present, likely secondary to the patient's severe COPD.

Key Concept

Patients with a primary metabolic acidosis must be evaluated with Winter's formula to determine if respiratory compensation is adequate; a pCO2 higher than expected indicates a concomitant respiratory acidosis.

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