All practice questions

8270 questions

All types8,270 Multiple choice4,249 Multiple select325 Numeric160 Matching1,849 Ordering1,687

Progressive respiratory distress over the past 72 hours brings a retired teacher to the emergency department. The 72-year-old man reports that he cannot sleep flat in bed due to a suffocating sensation, which is accompanied by a cough producing frothy sputum. He has a 45-pack-year history of smoking, hypertension, and type 2 diabetes mellitus. His daily medications are amlodipine and metformin. Vital signs include a temperature of 37.1°C (98.8°F), blood pressure of 162/94 mm Hg, heart rate of 108/min, and respiratory rate of 26/min. Pulse oximetry on ambient air indicates an oxygen saturation of 88%. On physical examination, the jugular veins are distended to 10 cm H2O above the sternal angle. Auscultation of the lungs reveals widespread expiratory wheezes and fine crackles at both lung bases. Cardiac examination shows a regular, rapid rhythm with a distinct third heart sound (S3). Examination of the lower extremities shows bilateral 1+ pitting edema. Electrocardiography shows sinus tachycardia without ischemic changes. Chest radiography is pending. Which of the following is the most appropriate next step in management?

Nebulized albuterol and ipratropium

Oral prednisone

Intravenous furosemide

Intravenous ceftriaxone and azithromycin

Measurement of serum brain natriuretic peptide

Show answer & explanation

Answer: Intravenous furosemide

Answer

Intravenous furosemide

The correct answer is the administration of intravenous furosemide. The patient's clinical presentation—orthopnea, elevated jugular venous pressure, bibasilar crackles, an S3 gallop, and peripheral edema—is highly specific for acute decompensated heart failure (ADHF) leading to pulmonary edema. The presence of wheezing in this context is often referred to as 'cardiac asthma,' which occurs due to peribronchial edema causing airway narrowing. Patients with a significant smoking history are at high risk for COPD, which can make the differentiation challenging, but the clear signs of volume overload confirm ADHF. The initial management of ADHF focuses on preload reduction and symptom relief, which is primarily achieved with intravenous loop diuretics (e.g., furosemide) and supplemental oxygen. Waiting for further diagnostic testing is inappropriate when the clinical diagnosis is evident and the patient is in acute respiratory distress.

Step-by-Step Solution

Analyze the patient's symptoms and vital signs.

The patient has acute respiratory distress, hypoxemia, orthopnea, and a cough producing frothy sputum.

To determine the severity and nature of the respiratory compromise.

Evaluate the physical examination findings.

Findings include elevated jugular venous pressure, bilateral crackles, wheezing, an S3 gallop, and peripheral edema.

To differentiate between primary pulmonary and primary cardiac causes of dyspnea.

Synthesize the findings to establish a clinical diagnosis.

The combination of volume overload signs (JVP, S3, edema) and pulmonary edema confirms acute decompensated heart failure. The wheezing represents 'cardiac asthma' rather than a primary obstructive airway process.

Accurate diagnosis is required to select the appropriate targeted therapy and avoid harmful interventions.

Select the most appropriate initial pharmacological management.

Intravenous furosemide is chosen.

Loop diuretics provide rapid preload reduction and diuresis, which are urgently needed to relieve pulmonary congestion in acute decompensated heart failure.

Key Concept

Clinical differentiation and initial management of acute decompensated heart failure presenting with cardiac asthma.

Question 1602Question →

A 25-year-old woman with a history of type 1 diabetes mellitus presents to the emergency department with generalized weakness, nausea, and abdominal pain for the past 24 hours. She has been unable to eat and has missed her last two doses of insulin. Her blood pressure is 110/70 mm Hg, pulse is 115/min, and respirations are 24/min. Physical examination shows dry mucous membranes and a fruity odor to her breath.

Laboratory studies show:
Serum sodium: 140 mEq/L
Serum potassium: 4.8 mEq/L
Serum chloride: 104 mEq/L
Serum bicarbonate: 12 mEq/L
Blood urea nitrogen: 28 mg/dL
Serum creatinine: 1.2 mg/dL
Plasma glucose: 450 mg/dL

Arterial blood gas analysis on room air:
pH: 7.25
pCO2: 26 mm Hg
pO2: 95 mm Hg

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

Primary high anion gap metabolic acidosis with appropriate respiratory compensation

Primary high anion gap metabolic acidosis with concurrent respiratory alkalosis

Primary high anion gap metabolic acidosis with concurrent respiratory acidosis

Primary normal anion gap metabolic acidosis with appropriate respiratory compensation

Mixed high anion gap metabolic acidosis and primary metabolic alkalosis

Show answer & explanation

Answer: Primary high anion gap metabolic acidosis with appropriate respiratory compensation

Answer

Primary high anion gap metabolic acidosis with appropriate respiratory compensation

This patient presents with classic signs of diabetic ketoacidosis, confirmed by a low pH (

7.25

) and low serum bicarbonate (

12

mEq/L), indicating a primary metabolic acidosis. The anion gap is calculated as

Na^+ - (Cl^- + HCO_3^-)

, which is

140 - (104 + 12) = 24

mEq/L. Because the normal anion gap is

8

12

mEq/L, this is a high anion gap metabolic acidosis (HAGMA). To determine if respiratory compensation is appropriate, Winter's formula must be applied: Expected

pCO_2 = (1.5 \times HCO_3^-) + 8 \pm 2

. For this patient, Expected

pCO_2 = (1.5 \times 12) + 8 = 18 + 8 = 26 \pm 2

mm Hg. The measured pCO2 is

26

mm Hg, which falls exactly within this range. Therefore, the patient has a primary HAGMA with appropriate respiratory compensation.

Step-by-Step Solution

Identify the primary acid-base disturbance using the pH and serum bicarbonate.

pH is 7.25 (acidemia) and bicarbonate is 12 mEq/L (low), indicating a primary metabolic acidosis.

Determining the primary disorder is the first step in basic acid-base analysis.

Calculate the anion gap.

Anion Gap =

140 - (104 + 12) = 24

mEq/L.

Metabolic acidosis must be categorized into high anion gap or normal anion gap to narrow down the differential diagnosis.

Calculate the expected respiratory compensation using Winter's formula.

Expected

pCO_2 = (1.5 \times 12) + 8 = 26 \pm 2

mm Hg.

Calculating the expected pCO2 determines if the physiological respiratory response is adequate or if a secondary respiratory disorder exists.

Compare the measured pCO2 to the expected pCO2.

The measured pCO2 (26 mm Hg) is exactly within the expected range (24 to 28 mm Hg).

Because the measured pCO2 matches the expected value, there is appropriate respiratory compensation without a superimposed respiratory disorder.

Key Concept

Evaluation of acid-base disorders using the anion gap and Winter's formula to determine primary disturbances and physiological compensation.

Question 1603Question →

A 10-day-old female neonate is evaluated in the neonatal intensive care unit for sudden clinical deterioration. She was born at 29 weeks of gestation via urgent cesarean delivery due to severe maternal preeclampsia. Birth weight was 1,150 g (2 lb 8 oz). Apgar scores were 5 and 7 at 1 and 5 minutes, respectively. Over the past 8 hours, the neonate has developed temperature instability and frequent episodes of apnea and bradycardia. She is currently supported with continuous positive airway pressure. She had been tolerating advancing volumes of expressed maternal milk via an orogastric tube; however, the most recent feed yielded a large bilious gastric residual. Temperature is 35.8°C (96.4°F), pulse is 175/min, and respirations are 68/min. The abdomen is grossly distended, shiny, and erythematous with absent bowel sounds. Complete blood count shows a leukocyte count of 2,200/mm³ and a platelet count of 82,000/mm³. Arterial blood gas analysis reveals a pH of 7.26, $\text{pCO}_2$ of 38 mm Hg, and $\text{HCO}_3^-$ of 15 mEq/L. An anteroposterior abdominal radiograph demonstrates prominent, dilated bowel loops with linear radiolucencies in the intestinal wall, without free air under the diaphragm. Which of the following is the most appropriate next step in management?

Bowel rest, orogastric decompression, and broad-spectrum intravenous antibiotics

Immediate exploratory laparotomy with bowel resection

Transport to radiology for a computed tomography scan of the abdomen

Discontinuation of enteral feeds and empiric initiation of oral vancomycin therapy

Intravenous sodium bicarbonate administration and continuous observation

Show answer & explanation

Answer: Bowel rest, orogastric decompression, and broad-spectrum intravenous antibiotics

Answer

The most appropriate next step is to initiate medical management comprising bowel rest, orogastric decompression, and broad-spectrum intravenous antibiotics.

This neonate's clinical presentation of temperature instability, apnea, bilious gastric residuals, and an erythematous, distended abdomen strongly suggests necrotizing enterocolitis (NEC). The diagnosis is confirmed by the pathognomonic radiographic finding of pneumatosis intestinalis (linear radiolucencies in the intestinal wall representing submucosal gas). Because the radiograph does not show pneumoperitoneum (free air under the diaphragm), the bowel has not yet perforated. The standard initial management for unperforated NEC is entirely medical and focuses on stabilizing the infant and preventing further bowel injury. This consists of immediate cessation of enteral feeds (bowel rest), placement of an orogastric tube for gastric decompression, fluid resuscitation, and initiation of broad-spectrum intravenous antibiotics to cover intestinal flora (typically ampicillin, gentamicin, and metronidazole or clindamycin).

Step-by-Step Solution

Analyze the clinical presentation and risk factors.

A premature neonate (29 weeks) presents with feeding intolerance (bilious residuals), systemic instability (apnea, bradycardia, hypothermia), and abdominal signs (distension, erythema).

These findings are classic for a severe neonatal gastrointestinal emergency.

Interpret the radiographic and laboratory findings.

The abdominal radiograph shows linear radiolucencies in the bowel wall (pneumatosis intestinalis) without free air. Labs show leukopenia, thrombocytopenia, and metabolic acidosis.

Pneumatosis intestinalis is the pathognomonic finding for necrotizing enterocolitis (NEC). The lack of free air indicates there is no gross perforation yet (Stage II NEC).

Determine the optimal management based on disease staging.

Unperforated NEC requires immediate aggressive medical management: stopping enteral feeds, decompressing the stomach, giving IV fluids, and starting broad-spectrum IV antibiotics.

Surgical intervention is reserved for perforated bowel or failure to improve with medical therapy.

Key Concept

The primary management of unperforated necrotizing enterocolitis (NEC) consists of strict bowel rest, gastric decompression, intravenous fluids, and broad-spectrum intravenous antibiotics.

Question 1604Question →

A 72-year-old man is evaluated in the hospital for acute-onset shortness of breath. He is currently on postoperative day 3 following an open partial colectomy for colon cancer. He has a history of hypertension, type 2 diabetes mellitus, and chronic kidney disease. Two hours ago, routine laboratory studies were obtained:

Test	Result
Hemoglobin	$6.8 \text{ g/dL}$
Leukocytes	$8,500/\mu\text{L}$
Platelets	$210,000/\mu\text{L}$
Sodium	$138 \text{ mEq/L}$
Potassium	$4.2 \text{ mEq/L}$
Blood urea nitrogen	$35 \text{ mg/dL}$
Creatinine	$1.8 \text{ mg/dL}$

Due to the symptomatic anemia, a transfusion of packed red blood cells was initiated. Forty-five minutes into the transfusion, the patient develops severe dyspnea and a nonproductive cough.

His temperature is $38.1^\circ\text{C} (100.6^\circ\text{F})$ , blood pressure is $178/96 \text{ mmHg}$ , pulse is $115/\text{min}$ , and respirations are $28/\text{min}$ . Pulse oximetry is $87\%$ on room air.

Physical examination reveals a patient in acute respiratory distress. The jugular veins are distended to the angle of the mandible while sitting at 45 degrees. Cardiac auscultation reveals a regular tachycardia with a prominent $S_{3}$ gallop. Pulmonary auscultation reveals bilateral basilar crackles.

An arterial blood gas on room air shows:
pH: $7.49$
pCO2: $30 \text{ mmHg}$
pO2: $56 \text{ mmHg}$
HCO3: $23 \text{ mEq/L}$

The blood transfusion is immediately stopped, and supplemental oxygen is provided. Which of the following is the most appropriate next step in management?

Administer nebulized albuterol and ipratropium

Administer broad-spectrum intravenous antibiotics

Obtain a urinalysis and urine culture

Administer intravenous furosemide

Administer intravenous sodium bicarbonate

Show answer & explanation

Answer: Administer intravenous furosemide

Answer

The most appropriate next step in management is to administer intravenous furosemide to treat Transfusion-Associated Circulatory Overload (TACO).

This patient is experiencing Transfusion-Associated Circulatory Overload (TACO). Risk factors for TACO include advanced age, underlying cardiovascular disease, and chronic kidney disease (which this patient has). The rapid administration of blood products leads to an acute expansion of the intravascular space, causing cardiogenic pulmonary edema. The classic clinical presentation includes acute dyspnea, hypoxemia, hypertension, tachycardia, jugular venous distention, and an

S_{3}

gallop. The arterial blood gas shows an uncompensated respiratory alkalosis due to hypoxia-driven tachypnea, rather than an underlying metabolic derangement. Management of TACO requires immediately halting the transfusion, providing respiratory support (such as supplemental oxygen or positive pressure ventilation), and administering intravenous loop diuretics (e.g., furosemide) to rapidly decrease the volume overload.

Step-by-Step Solution

Analyze the patient's acute presentation during the packed red blood cell transfusion.

The patient developed severe dyspnea, hypoxemia, hypertension, jugular venous distention, and an

S_{3}

gallop.

Identifying the timing of symptom onset and the hemodynamic profile is crucial for differentiating between types of acute transfusion reactions.

Differentiate between the primary causes of acute respiratory distress following a transfusion.

The combination of acute pulmonary edema, hypertension, and prominent signs of cardiac volume overload (JVD,

S_{3}

gallop) strongly points to Transfusion-Associated Circulatory Overload (TACO).

TACO is a hydrostatic pulmonary edema caused by rapid intravascular volume expansion, whereas TRALI involves immune-mediated increased pulmonary capillary permeability typically presenting with normal or low blood pressure and no signs of fluid overload.

Determine the most appropriate immediate management for TACO based on the diagnosis.

In addition to stopping the transfusion and providing respiratory support, administering intravenous diuretics is required.

Loop diuretics, such as furosemide, promote renal fluid excretion and provide venodilation, rapidly decreasing the excessive intravascular volume and relieving cardiogenic pulmonary edema.

Key Concept

Transfusion-Associated Circulatory Overload (TACO) presents with signs of cardiogenic volume overload (hypertension, JVD,

S_{3}

gallop, pulmonary crackles) and is managed by halting the transfusion, providing oxygen, and administering intravenous diuretics.

Question 1605Question →

A 27-year-old graduate student is brought to the university health clinic by his roommate. The roommate reports that for the past 14 weeks, the patient has been barricading himself in their shared apartment, claiming that rival researchers are trying to steal his thoughts using microwave beams. The patient has been hearing two voices arguing about his research outside his window, even when no one is there. He has not attended classes or bathed regularly during this time. Prior to this, he was a top-performing student with a wide circle of friends and no prior psychiatric history. Medical history is unremarkable. Vital signs and physical examination are within normal limits. A urine toxicology screen is negative. Which of the following is the most likely diagnosis?

Brief psychotic disorder

Delusional disorder

Schizoaffective disorder

Schizophrenia

Schizophreniform disorder

Show answer & explanation

Answer: Schizophreniform disorder

Answer

Schizophreniform disorder

The correct diagnosis is schizophreniform disorder. The patient has clear active-phase symptoms of psychosis (delusions and auditory hallucinations) along with functional impairment. The defining feature for his diagnosis is the duration of his illness. His symptoms have been present for 14 weeks. According to DSM-5 criteria, schizophreniform disorder is diagnosed when symptoms of schizophrenia are present for at least 1 month but less than 6 months. If his symptoms persist beyond 6 months, the diagnosis would subsequently be changed to schizophrenia.

Step-by-Step Solution

Identify the primary psychiatric symptoms presented in the clinical vignette.

The patient exhibits paranoid delusions (belief that researchers are stealing thoughts via microwaves) and auditory hallucinations (hearing two voices arguing).

Establishing the presence of active-phase psychotic symptoms is required to navigate the differential diagnosis of psychotic disorders.

Assess the presence of major mood episodes.

There is no mention of a concurrent major depressive or manic episode.

The absence of prominent mood symptoms rules out schizoaffective disorder, bipolar disorder with psychotic features, and major depressive disorder with psychotic features.

Determine the total duration of the current symptomatic episode.

The symptoms have been present continuously for 14 weeks (approximately 3.5 months).

The precise duration of symptoms is the critical distinguishing factor among brief psychotic disorder, schizophreniform disorder, and schizophrenia.

Apply the temporal diagnostic criteria to the patient's presentation.

The duration of 14 weeks is greater than 1 month but less than 6 months.

Symptoms lasting <1 month indicate brief psychotic disorder, 1 to 6 months indicate schizophreniform disorder, and >6 months indicate schizophrenia.

Key Concept

Distinguishing brief psychotic disorder, schizophreniform disorder, and schizophrenia based strictly on the duration of clinical symptoms.

Question 1606Question →

During routine morning rounds on postoperative day 3, a 51-year-old man is evaluated after an elective open reduction and internal fixation of a right tibial fracture. He reports feeling mildly fatigued but is participating in early physical therapy. An indwelling urinary catheter was placed intraoperatively and removed on postoperative day 1. His temperature is 38.6°C (101.5°F), blood pressure is 125/80 mmHg, heart rate is 88/min, and respiratory rate is 16/min. Oxygen saturation is 98% on room air. Physical examination reveals clear breath sounds bilaterally. The right lower extremity surgical dressings are intact, with no surrounding erythema, induration, or unusual swelling. Palpation of the left calf is non-tender. When questioned further, he notes increased urinary frequency and mild suprapubic discomfort since the previous evening. Which of the following is the most appropriate next step in management?

Obtain a urinalysis and urine culture

Perform a portable chest radiograph

Order a venous duplex ultrasound of the bilateral lower extremities

Remove the surgical dressings to inspect the incision site

Begin empiric intravenous piperacillin-tazobactam therapy

Show answer & explanation

Answer: Obtain a urinalysis and urine culture

Answer

Obtain a urinalysis and urine culture

The correct answer addresses the most likely etiology of this patient's presentation. Postoperative fever is commonly evaluated using the '5 Ws' mnemonic (Wind, Water, Walking, Wound, Wonder drugs/What did we do). This patient is on postoperative day 3, a timeline most consistent with 'Water', or a urinary tract infection (UTI). His recent Foley catheter removal and localized symptoms (urinary frequency, suprapubic discomfort) strongly support this diagnosis. The standard next step in management is to confirm the presence of infection and identify the organism via a urinalysis and urine culture prior to starting targeted antibiotics.

Step-by-Step Solution

Evaluate the timing of the postoperative fever.

The patient developed a fever on postoperative day 3.

The postoperative day (POD) strongly correlates with specific etiologies of fever (the '5 Ws': Wind, Water, Walking, Wound, Wonder drugs).

Correlate the fever timing with clinical signs and symptoms.

The patient has urinary frequency and suprapubic discomfort following recent Foley catheter removal.

Fever on POD 3-5 ('Water') is classically associated with urinary tract infections (UTIs), especially in patients who had an indwelling catheter.

Determine the most appropriate diagnostic intervention.

Urinalysis and urine culture should be ordered.

Before initiating any targeted antibiotic therapy for a suspected UTI, objective evidence of infection and pathogen identification are required.

Key Concept

The timing of postoperative fever is a critical clue to its etiology. Fever on postoperative days 3 to 5 is highly suggestive of a urinary tract infection (the 'Water' in the 5 Ws), warranting urinalysis and urine culture.

Question 1607Question →

A 12-hour-old male neonate is evaluated in the nursery due to rapid breathing. He was born at 38 weeks gestation via scheduled cesarean delivery for a breech presentation. The pregnancy was uncomplicated, and maternal group B Streptococcus screening was negative. Apgar scores were 8 and 9 at 1 and 5 minutes. His temperature is 36.9°C (98.4°F), heart rate is 148/min, respiratory rate is 74/min, and oxygen saturation is 96% on room air. Physical examination shows a vigorous infant with mild subcostal retractions. Breath sounds are clear and equal bilaterally without murmurs. Skin examination reveals multiple scattered 2-mm pustules on a broad erythematous base across the anterior chest, abdomen, and proximal extremities. A chest radiograph demonstrates hyperinflation, prominent perihilar linear densities, and fluid within the interlobar fissures. Which of the following is the most appropriate next step in management?

Supportive care and clinical observation

Blood culture and empirical intravenous ampicillin and gentamicin

Intravenous acyclovir and contact precautions

Endotracheal intubation and exogenous surfactant administration

Intravenous furosemide and fluid restriction

Show answer & explanation

Answer: Supportive care and clinical observation

Answer

The most appropriate next step in management is supportive care and clinical observation.

The correct approach is supportive care and clinical observation. This neonate presents with two distinct but common benign conditions: transient tachypnea of the newborn (TTN) and erythema toxicum neonatorum (ETN). TTN is caused by retained fetal lung fluid and classically presents with tachypnea, mild respiratory distress, and a chest radiograph showing hyperinflation, perihilar streaking, and fluid in the interlobar fissures. It is particularly common in term infants delivered via scheduled cesarean section without a preceding trial of labor, as they miss the catecholamine-induced fluid clearance that typically occurs during vaginal delivery. TTN is self-limiting and resolves with supportive care within 24 to 72 hours. Furthermore, the infant's rash—scattered pustules on an erythematous base—is classic for ETN, a benign, asymptomatic rash that appears in the first few days of life and spontaneously resolves without treatment. Therefore, routine monitoring and supportive care are the only necessary interventions.

Step-by-Step Solution

Analyze the patient's respiratory presentation and radiographic findings.

Tachypnea, mild retractions, and a chest radiograph showing hyperinflation and fluid in the fissures in a term infant born via cesarean delivery indicate transient tachypnea of the newborn (TTN).

TTN occurs due to delayed clearance of fetal alveolar fluid, often exacerbated by a lack of labor, which normally provides a catecholamine surge to help clear the fluid.

Evaluate the dermatologic findings on the physical examination.

The scattered pustules on an erythematous base on the chest and extremities describe erythema toxicum neonatorum (ETN).

ETN is a common, benign, self-limited rash appearing in the first few days of life, requiring no pharmacologic intervention.

Determine the appropriate overarching management strategy.

Supportive care and monitoring.

Since both TTN and ETN are benign and resolve spontaneously, invasive diagnostics, targeted pharmacotherapy, and broad-spectrum antibiotics are contraindicated. The infant simply needs close observation and supportive respiratory care if the work of breathing increases.

Key Concept

Recognition and supportive management of benign neonatal conditions (Transient Tachypnea of the Newborn and Erythema Toxicum Neonatorum) while avoiding unnecessary invasive testing or pharmacotherapy.

Estimated Time:1m 30s

Question 1608Question →

A $74$ -year-old man is evaluated on the postoperative wards on hospital day $5$ following an urgent open reduction and internal fixation of a right femoral neck fracture. For the past $3$ days, he has experienced progressive abdominal distension, nausea, and a failure to pass flatus or stool. $48$ hours ago, all opioid analgesics were discontinued, and he was placed on bowel rest with nasogastric tube decompression and intravenous fluid support. Despite these measures, his symptoms have worsened. His temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), pulse is $88/\text{min}$ , blood pressure is $138/82 \text{ mmHg}$ , and respirations are $16/\text{min}$ . The abdomen is massively distended and tympanitic to percussion. It is mildly tender diffusely, but there is no guarding, rigidity, or rebound tenderness. Bowel sounds are absent. Laboratory studies show a leukocyte count of $8,000/\text{mm}^3$ , potassium of $4.2 \text{ mEq/L}$ , and magnesium of $2.1 \text{ mEq/L}$ . An electrocardiogram shows normal sinus rhythm. Computed tomography of the abdomen and pelvis with intravenous contrast reveals marked dilation of the colon extending from the cecum to the splenic flexure, with a maximal cecal diameter of $11.8 \text{ cm}$ . There is no discrete transition point, obstructing mass, or pneumoperitoneum. Which of the following is the most appropriate next step in management?

Intravenous neostigmine

Colonoscopic decompression

Immediate exploratory laparotomy

Oral polyethylene glycol

Intravenous piperacillin-tazobactam

Show answer & explanation

Answer: Intravenous neostigmine

Answer

Intravenous neostigmine is the most appropriate next step for this patient's acute colonic pseudo-obstruction.

The correct answer is intravenous neostigmine. This patient has acute colonic pseudo-obstruction (Ogilvie syndrome), characterized by massive dilation of the colon in the absence of a mechanical obstruction. It classically occurs in elderly, hospitalized patients following surgery or severe medical illness. Initial management consists of conservative measures: bowel rest, nasogastric and rectal tube decompression, correction of electrolyte abnormalities (especially hypokalemia and hypomagnesemia), and discontinuation of offending medications (e.g., opioids, anticholinergics). If a patient fails

24

48

hours of conservative management, or if the cecal diameter rapidly approaches or exceeds

12 \text{ cm}

(which poses a high risk of ischemia and perforation), active decompression is indicated. The first-line active intervention is intravenous neostigmine, an acetylcholinesterase inhibitor that stimulates colonic motility. Since this patient has failed

48

hours of conservative therapy and has a cecal diameter of

11.8 \text{ cm}

with a normal EKG (no bradycardia to contraindicate the drug), neostigmine is the most appropriate next step.

Step-by-Step Solution

Analyze the clinical presentation and imaging findings.

The patient has massive colonic dilation (

11.8 \text{ cm}

) without a mechanical transition point in the postoperative setting.

Establishing the diagnosis of acute colonic pseudo-obstruction (Ogilvie syndrome) and ruling out mechanical small or large bowel obstruction.

Evaluate the response to initial therapies.

The patient has already undergone

48

hours of appropriate conservative management (NPO, NG tube, IV fluids, electrolyte correction, discontinuation of opioids) without improvement.

Determines whether to continue supportive care or escalate to active decompression.

Assess the severity of dilation and check for contraindications to specific therapies.

The cecal diameter is critically enlarged (approaching

12 \text{ cm}

), warranting active decompression. The EKG shows normal sinus rhythm, indicating no bradycardic contraindication to acetylcholinesterase inhibitors.

Guides the selection of pharmacologic versus endoscopic decompression.

Key Concept

Management of Acute Colonic Pseudo-obstruction (Ogilvie Syndrome)

Question 1609Question →

A 58-year-old man with a history of chronic alcohol use disorder is brought to the emergency department due to profound weakness and a four-day history of intractable vomiting. He reports being unable to keep any food or fluids down. On physical examination, he appears lethargic and has dry mucous membranes with decreased skin turgor.

Laboratory studies reveal the following:

Serum:
Sodium: 140 mEq/L
Potassium: 3.1 mEq/L
Chloride: 88 mEq/L
Bicarbonate: 14 mEq/L
Blood urea nitrogen: 35 mg/dL
Creatinine: 1.6 mg/dL

Arterial blood gas on room air reveals a pH of 7.32 and a $pCO_2$ of 29 mm Hg. The physician suspects a complex mixed acid-base disorder driven by alcoholic ketoacidosis and protracted emesis.

Assuming a baseline normal anion gap of 12 mEq/L and a baseline normal serum bicarbonate of 24 mEq/L, what is the calculated delta-delta ratio ( $\Delta AG / \Delta HCO_3^-$ ) for this patient?

Show answer & explanation

Answer: 2.6

Answer

2.6

In a patient presenting with a high anion gap metabolic acidosis, calculating the delta-delta ratio is essential to evaluate for mixed metabolic disorders. First, the patient's anion gap is calculated as

140 - (88 + 14) = 38

mEq/L. The

\Delta AG

is the patient's calculated AG minus the normal baseline AG (

38 - 12 = 26

). The

\Delta HCO_3^-

is the normal baseline

HCO_3^-

minus the patient's measured

HCO_3^-

(

24 - 14 = 10

). The delta-delta ratio is

26 / 10 = 2.6

. Because 2.6 is greater than 2.0, this confirms a concurrent metabolic alkalosis superimposed on the high anion gap metabolic acidosis, which perfectly aligns with the clinical history of alcoholic ketoacidosis paired with profound vomiting.

Step-by-Step Solution

Calculate the actual anion gap (AG).

AG = 140 - (88 + 14) = 38

mEq/L.

An elevated anion gap confirms the presence of a high anion gap metabolic acidosis (HAGMA).

Calculate the delta anion gap (

\Delta AG

\Delta AG = 38 - 12 = 26

mEq/L.

This value represents the excess unmeasured anions contributing to the acidosis.

Calculate the delta bicarbonate (

\Delta HCO_3^-

\Delta HCO_3^- = 24 - 14 = 10

mEq/L.

This value represents the apparent fall in bicarbonate due to buffering the excess acid.

Calculate the delta-delta ratio.

\Delta AG / \Delta HCO_3^- = 26 / 10 = 2.6

A ratio greater than 2.0 indicates that the bicarbonate level is higher than expected, revealing a concurrent metabolic alkalosis (e.g., from vomiting) superimposed on the HAGMA.

Key Concept

The delta-delta ratio (

\Delta AG / \Delta HCO_3^-

) is used in the setting of a high anion gap metabolic acidosis to identify hidden mixed acid-base disorders. A ratio > 2.0 indicates a concurrent metabolic alkalosis, whereas a ratio < 1.0 indicates a concurrent normal anion gap metabolic acidosis.

Estimated Time:1m 30s

Question 1610Question →

A 26-year-old woman, gravida 1, para 0, presents to the clinic for a scheduled prenatal evaluation at 26 weeks gestation. She has no complaints other than mild, intermittent fatigue. The patient is taking a daily prenatal vitamin containing iron and folic acid. Her vital signs are temperature 36.8°C (98.2°F), blood pressure 110/70 mm Hg, heart rate 82/min, and respiratory rate 14/min. Fetal heart tones are 145/min.

Laboratory studies obtained today show the following:

Laboratory Study	Result	Reference Range (Nonpregnant)
Hemoglobin	10.7 g/dL	12.0 - 16.0 g/dL
Hematocrit	32%	36% - 46%
Mean corpuscular volume	89 fL	80 - 100 fL
Leukocyte count	9,500/mm³	4,500 - 11,000/mm³
Platelet count	210,000/mm³	150,000 - 400,000/mm³

At her initial visit at 9 weeks gestation, her hemoglobin was 12.8 g/dL. Which of the following is the most likely primary mechanism responsible for this patient's current hematologic findings?

Disproportionate increase in plasma volume relative to erythrocyte mass

Depletion of maternal iron stores due to fetal demand

Impaired absorption of dietary folate in the small intestine

Suppression of bone marrow erythrocyte production

Destruction of circulating erythrocytes in the reticuloendothelial system

Show answer & explanation

Answer: Disproportionate increase in plasma volume relative to erythrocyte mass

Answer

The hematologic findings are caused by a disproportionate increase in plasma volume relative to erythrocyte mass, known as physiologic anemia of pregnancy.

During normal pregnancy, maternal blood volume undergoes significant changes. Plasma volume increases continuously starting in the first trimester, expanding by approximately 40% to 50% above baseline. Simultaneously, the total red blood cell (erythrocyte) mass also increases, but only by about 20% to 30%. Because the expansion of plasma volume outpaces the production of new red blood cells, hemodilution occurs. This results in a physiologic, normocytic anemia that typically reaches its nadir during the late second or early third trimester. According to the American College of Obstetricians and Gynecologists (ACOG), true anemia in the second trimester is defined as a hemoglobin level strictly less than 10.5 g/dL. Because this patient's hemoglobin is 10.7 g/dL and her mean corpuscular volume (MCV) is perfectly normal (89 fL), her presentation is a classic example of this normal, healthy physiologic adaptation rather than a disease state.

Step-by-Step Solution

Interpret the laboratory findings.

The patient has a mild, normocytic anemia (hemoglobin 10.7 g/dL, MCV 89 fL) with normal white blood cell and platelet counts at 26 weeks gestation.

Establishing the type of anemia (normocytic vs. microcytic vs. macrocytic) helps differentiate normal pregnancy adaptations from pathological deficiencies.

Compare the hemoglobin level to pregnancy-specific reference ranges.

The hemoglobin is above 10.5 g/dL, which is considered the lower limit of normal for the second trimester of pregnancy.

Standard nonpregnant reference ranges do not apply; correctly applying pregnancy thresholds prevents misdiagnosing a normal adaptation as a disease state.

Identify the underlying physiologic mechanism.

The findings represent physiologic dilutional anemia caused by plasma volume expanding more than red blood cell mass.

Recognizing this mechanism confirms that the patient's presentation requires only reassurance and continued routine prenatal care.

Key Concept

Physiologic Anemia of Pregnancy

Question 1611Question →

An oncology consultation is requested for a 34-year-old man admitted to the intensive care unit due to profound pancytopenia and severe watery diarrhea. The patient has a history of classical Hodgkin lymphoma, for which he completed systemic chemotherapy three months ago. Two weeks prior to this admission, he presented to an outpatient clinic with symptomatic anemia and received two units of packed red blood cells donated by his healthy biological brother. Over the last four days, he has developed a diffuse, erythematous maculopapular rash involving the palms and soles, abdominal cramping, and jaundice. Vital signs reveal a temperature of $39.4^\circ\text{C}$ ( $102.9^\circ\text{F}$ ), blood pressure of 105/65 mmHg, and heart rate of 115/min. Laboratory studies show:

Parameter	Result
Hemoglobin	6.2 g/dL
White blood cell count	$800/\mu\text{L}$ (Neutrophils: 10%)
Platelet count	$15,000/\mu\text{L}$
Total bilirubin	4.5 mg/dL
Alkaline phosphatase	420 U/L
Alanine aminotransferase (ALT)	180 U/L
Aspartate aminotransferase (AST)	150 U/L

Which of the following pre-transfusion blood product modifications would have most likely prevented this patient's current condition?

Gamma irradiation

Leukoreduction

Washing with saline

Solvent-detergent treatment

Warming to

37^\circ\text{C}

Show answer & explanation

Answer: Gamma irradiation

Answer

Gamma irradiation

Gamma irradiation of cellular blood products (packed red blood cells and platelets) cross-links the DNA of donor T-lymphocytes, thereby rendering them incapable of proliferating. This is the only effective method to prevent transfusion-associated graft-versus-host disease (TA-GVHD). TA-GVHD is a rare, highly fatal complication that occurs when viable donor T-cells attack the recipient's tissues (classic tetrad: skin rash, diarrhea, liver dysfunction, and bone marrow aplasia/pancytopenia). Gamma irradiation is strictly indicated for susceptible populations, which notably includes patients with cellular immunodeficiencies (e.g., Hodgkin lymphoma, prior stem cell transplants, use of purine analogs) and any patient receiving a directed blood donation from a first-degree relative. In family-directed donations, shared HLA haplotypes prevent the recipient's immune system from recognizing the donor cells as foreign, allowing the donor T-cells to engraft and attack the unshared recipient HLA antigens.

Step-by-Step Solution

Analyze the patient's clinical presentation and timeline.

The patient developed a severe maculopapular rash, secretory diarrhea, hepatitis (elevated LFTs and bilirubin), and profound pancytopenia two weeks after receiving a blood transfusion.

Establishing the sequence of events and the affected organ systems (skin, GI tract, liver, bone marrow) points toward a systemic immunologic process.

Identify the underlying diagnosis based on the clinical triad and history.

The diagnosis is Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD).

TA-GVHD classically presents 1 to 4 weeks post-transfusion with rash, hepatomegaly/jaundice, diarrhea, and severe bone marrow aplasia (pancytopenia).

Determine the patient's specific risk factors for TA-GVHD.

The patient has a history of Hodgkin lymphoma (causing a cellular immunodeficiency) and received a directed blood donation from a first-degree relative.

TA-GVHD occurs when donor T-lymphocytes recognize the recipient as foreign and mount an attack, while the recipient cannot reject the donor cells. This happens in immunocompromised hosts or when an immunocompetent recipient receives blood from an HLA-haploidentical relative (the recipient does not recognize the donor as foreign).

Select the appropriate preventive measure.

Gamma irradiation of the cellular blood product.

Irradiation cross-links the DNA of donor T-lymphocytes, preventing their proliferation. It is strictly indicated for patients with Hodgkin lymphoma and for all directed donations from blood relatives.

Key Concept

Prevention of Transfusion-Associated Graft-Versus-Host Disease (TA-GVHD)

Estimated Time:2m 0s

Question 1612Question →

During her active phase of labor, a $28$ -year-old nulliparous woman at $40$ weeks gestation experiences a change in fetal monitoring patterns. She is currently receiving a continuous oxytocin infusion to augment labor. Her cervix is $6$ cm dilated and $90\%$ effaced. The external fetal monitor shows a baseline heart rate of $135$ /min with moderate variability. Following the peak of several recent uterine contractions, the fetal heart rate gradually drops to $110$ /min and slowly returns to the baseline after the contractions have completely ended. The maternal blood pressure is $120/75$ mm Hg and temperature is $36.8^{\circ}$ C ( $98.2^{\circ}$ F). Which of the following is the most appropriate next step in the management of this patient?

Stop the administration of oxytocin

Transfer the patient to the operating room for a cesarean birth

Continue current management and provide reassurance to the patient

Administer intravenous broad-spectrum antibiotics

Perform an emergent vacuum-assisted vaginal delivery

Show answer & explanation

Answer: Stop the administration of oxytocin

Answer

Stop the administration of oxytocin

The correct answer is to stop the administration of oxytocin. The patient is experiencing late decelerations, defined as gradual decreases in the fetal heart rate where the nadir occurs after the peak of the uterine contraction. This pattern indicates uteroplacental insufficiency, which can lead to fetal hypoxemia and acidemia. The initial approach to late decelerations is intrauterine resuscitation to optimize fetal oxygenation. Core steps include discontinuing uterotonics like oxytocin (to reduce uterine activity and restore placental blood flow), repositioning the patient to the left lateral decubitus position (to relieve aortocaval compression), and administering an intravenous fluid bolus.

Step-by-Step Solution

Analyze the fetal heart rate (FHR) tracing described in the vignette.

The FHR shows a normal baseline of 135/min with moderate variability, but recurrent, gradual decreases that begin after the peak of contractions and return to baseline after the contractions end.

Accurate interpretation of the FHR tracing is essential to determine fetal well-being.

Diagnose the specific type of FHR deceleration.

The pattern of decelerations with an onset, nadir, and recovery delayed in relation to the uterine contraction represents late decelerations.

Late decelerations are a key indicator of uteroplacental insufficiency and potential fetal hypoxemia.

Determine the most appropriate initial management for late decelerations.

The immediate goal is intrauterine resuscitation to improve placental blood flow and fetal oxygenation. The first step in a patient receiving oxytocin is to discontinue the infusion.

Stopping oxytocin decreases uterine contraction frequency and intensity, immediately improving uteroplacental perfusion.

Key Concept

Late decelerations on fetal heart rate monitoring indicate uteroplacental insufficiency. The initial management consists of intrauterine resuscitation, which includes discontinuing uterotonics (e.g., oxytocin), repositioning the mother, and administering intravenous fluids or supplemental oxygen.

Question 1613Question →

Match each classic physical examination finding or auscultatory feature with the most likely associated pediatric congenital heart defect.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches are: Continuous machine-like murmur with Patent ductus arteriosus; Fixed, widely split S2 with Atrial septal defect; Harsh holosystolic murmur with Ventricular septal defect; and Upper extremity hypertension with delayed femoral pulses with Coarctation of the aorta.

Each listed congenital heart defect produces distinct, classic hemodynamic changes that manifest as pathognomonic physical exam findings. PDA creates continuous aorta-to-pulmonary flow. ASD creates right heart volume overload leading to a fixed split S2. VSD causes high-velocity systolic flow between ventricles. Coarctation physically restricts distal aortic flow, leading to a pressure differential between the upper and lower extremities.

Step-by-Step Solution

Analyze each physical examination finding to determine the underlying hemodynamic abnormality.

Identified continuous flow (left 1), right heart volume overload (left 2), systolic interventricular flow (left 3), and distal aortic obstruction (left 4).

Connecting clinical signs to pathophysiology is essential for diagnosing congenital heart defects.

Match the hemodynamic abnormality to the corresponding anatomical defect.

Aorta-to-pulmonary artery connection matches PDA. Interatrial connection matches ASD. Interventricular connection matches VSD. Aortic narrowing matches Coarctation.

Each structural defect predictably produces specific, pathognomonic physical findings.

Key Concept

Classic clinical presentations of major acyanotic congenital heart defects

Estimated Time:45s

Question 1614Question →

Match the following normal expected clinical findings during pregnancy with their primary physiological mechanism.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Supine dizziness is caused by mechanical obstruction of venous return; the drop in hemoglobin is due to intravascular fluid expansion exceeding erythrocyte production; heartburn is due to hormone-mediated smooth muscle relaxation; and breathlessness is caused by central stimulation of the respiratory center.

Each clinical finding corresponds to a specific, well-documented maternal physiological adaptation required to support a developing fetus, primarily driven by hormonal changes (like progesterone) or mechanical factors (like the growing uterus).

Step-by-Step Solution

Identify the cause of supine hypotensive syndrome.

It is matched with mechanical obstruction of venous return.

The gravid uterus physically compresses the inferior vena cava when the patient is in the supine position.

Identify the cause of the normal drop in hemoglobin during the second and third trimesters.

It is matched with intravascular fluid expansion exceeding erythrocyte production.

This disproportionate fluid increase creates a dilutional anemia.

Identify the cause of new-onset heartburn in pregnancy.

It is matched with hormone-mediated smooth muscle relaxation.

Progesterone relaxes the lower esophageal sphincter, allowing stomach acid to rise.

Identify the cause of physiologic dyspnea.

It is matched with central stimulation of the respiratory center.

Progesterone drives the respiratory center to take larger breaths, altering blood gas baselines slightly and causing a sensation of shortness of breath.

Key Concept

Normal maternal physiological adaptations to pregnancy

Question 1615Question →

During morning rounds in the intensive care unit, a 54-year-old woman experiences a sudden respiratory decompensation. She was intubated and mechanically ventilated three days prior due to acute respiratory distress syndrome (ARDS) secondary to severe influenza pneumonia. Over the past 5 minutes, the ventilator's high peak airway pressure alarm has activated repeatedly. Concurrently, her oxygen saturation has rapidly declined from $94\%$ to $82\%$ , and her blood pressure has fallen from $110/70\text{ mmHg}$ to $85/50\text{ mmHg}$ . Her heart rate is $128/\text{min}$ . Arrange the following steps in the most appropriate sequential order for evaluating and managing this patient's acute deterioration.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Disconnect and manually ventilate -> Auscultate and check tube -> Pass suction catheter -> Perform bedside imaging -> Execute definitive therapy.

The management of sudden respiratory decompensation and high peak airway pressures in a mechanically ventilated patient follows a standardized sequence designed to systematically identify and treat the most life-threatening causes first. The first step is to disconnect the patient from the mechanical ventilator and provide manual bag-valve-mask ventilation with

100\%

oxygen. This bypasses any potential equipment failure, immediately provides maximal oxygenation, and allows the clinician to manually assess lung compliance. Following this, the clinician should perform a rapid physical examination, including lung auscultation and checking the depth of the endotracheal tube, to assess for displacement (e.g., right mainstem intubation). The next step is to pass a suction catheter to rule out mechanical obstruction from a mucous plug. Once these immediate mechanical and airway issues are addressed, bedside imaging (such as point-of-care ultrasound or a portable chest radiograph) is utilized to diagnose structural problems like a pneumothorax, which is then managed with targeted definitive therapy such as a tube thoracostomy.

Step-by-Step Solution

Disconnect the ventilator and use a bag-valve-mask with

100\%

oxygen.

Rules out ventilator equipment failure and immediately supports oxygenation.

Ventilator malfunction must be bypassed immediately to ensure the patient is receiving oxygen and ventilation.

Auscultate bilaterally and assess endotracheal tube depth.

Assesses for endotracheal tube displacement and signs of pneumothorax.

Right mainstem intubation or extubation are common, easily correctable causes of sudden hypoxemia.

Pass a flexible suction catheter.

Checks for mechanical obstruction.

Mucous plugs or blood clots can obstruct the airway, leading to high peak pressures and hypoxia.

Perform bedside imaging (thoracic ultrasound or chest radiograph).

Definitively confirms the underlying pathology.

Once the airway is secured and equipment failure is ruled out, imaging differentiates between tension pneumothorax, severe atelectasis, or worsening ARDS.

Perform targeted definitive therapy.

Treats the identified cause of the decompensation.

Interventions like tube thoracostomy for a pneumothorax are performed based on the clinical and diagnostic findings.

Key Concept

The DOPE mnemonic (Displacement, Obstruction, Pneumothorax, Equipment) outlines the sequential approach to acute decompensation in a mechanically ventilated patient.

Estimated Time:2m 0s

Question 1616Question →

A $16$ -year-old female high school student presents to an outpatient neurology practice after suffering a generalized convulsion. The event occurred this morning shortly after she woke up. Her mother states that for the past $6$ months, the patient has experienced sudden, brief, symmetric muscle jerks in her upper extremities, predominantly occurring within the first hour of awakening. These jerks have occasionally caused her to drop her hairbrush. Her past medical history is unremarkable. She met all early developmental milestones on time, including sitting without support at $6$ months and walking independently at $12$ months. Neurologic examination today demonstrates normal tone, power, and reflexes. An interictal electroencephalogram shows bursts of bilateral, synchronous $4$ - to $6$ -Hz polyspike-and-wave discharges on a normal background. Which of the following statements regarding this patient's diagnosis and management are correct? (Select 2)

Select all that apply

The patient should be initiated on a broad-spectrum antiepileptic medication such as levetiracetam or valproic acid.

The involuntary muscle jerks and generalized seizures are highly sensitive to provocation by sleep deprivation and alcohol consumption.

The optimal initial pharmacotherapy is a targeted narrow-spectrum sodium channel blocker, such as carbamazepine or phenytoin.

The patient exhibits a history suggestive of motor developmental delay, warranting a comprehensive neurodevelopmental assessment.

This disorder typically spontaneously remits in the third decade of life, allowing for the eventual withdrawal of antiepileptic therapy.

Show answer & explanation

Answer: The patient should be initiated on a broad-spectrum antiepileptic medication such as levetiracetam or valproic acid.; The involuntary muscle jerks and generalized seizures are highly sensitive to provocation by sleep deprivation and alcohol consumption.

Answer

The correct statements are that the patient should be initiated on a broad-spectrum antiepileptic medication and that her symptoms are highly sensitive to provocation by sleep deprivation and alcohol consumption.

This patient's clinical presentation is classic for Juvenile Myoclonic Epilepsy (JME), the most common generalized epilepsy syndrome emerging in adolescence. JME is characterized by a triad of seizures: myoclonic jerks (typically in the morning, often causing patients to drop objects), generalized tonic-clonic seizures (frequently occurring shortly after awakening), and occasionally absence seizures. The diagnosis is confirmed by an electroencephalogram showing characteristic bilateral, symmetric

4

- to

6

-Hz polyspike-and-wave discharges. The correct management involves lifelong pharmacotherapy with a broad-spectrum antiepileptic drug, such as levetiracetam, valproic acid, or lamotrigine. Furthermore, counseling is critical because JME seizures are notoriously provoked by lifestyle factors, most notably sleep deprivation, alcohol consumption, and psychological stress.

Step-by-Step Solution

Analyze the clinical presentation and timeline.

The patient exhibits morning myoclonic jerks and a recent generalized tonic-clonic seizure, which is the classic presentation of a specific adolescent-onset epilepsy syndrome.

To identify the clinical triad associated with Juvenile Myoclonic Epilepsy (JME).

Interpret the diagnostic testing.

The interictal electroencephalogram shows

4

- to

6

-Hz polyspike-and-wave discharges.

These specific EEG findings are pathognomonic for JME and confirm the diagnosis.

Determine the appropriate management and prognosis based on the diagnosis.

JME requires lifelong treatment with broad-spectrum agents and extensive lifestyle counseling to avoid triggers.

Narrow-spectrum agents can worsen symptoms, and the condition rarely remits spontaneously with age.

Key Concept

Juvenile Myoclonic Epilepsy (JME) is an adolescent-onset generalized epilepsy syndrome characterized by morning myoclonus, generalized tonic-clonic seizures, and pathognomonic EEG findings. It requires lifelong broad-spectrum antiepileptic therapy and strict trigger avoidance.

Question 1617Question →

A 62-year-old woman is evaluated in the hospital for sudden-onset right leg pain and swelling. She was admitted 6 days ago for a pulmonary embolism and has been receiving a continuous intravenous infusion of unfractionated heparin. Today, her platelet count is 65,000/mm³, representing a significant drop from her admission baseline of 240,000/mm³. Lower extremity venous Doppler ultrasound reveals a new acute deep vein thrombosis in the right femoral vein. The 4Ts score is calculated and indicates a high clinical probability of heparin-induced thrombocytopenia (HIT).

Arrange the following steps for the diagnosis and long-term management of this patient in the most appropriate chronological order.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence is to first discontinue all heparin exposure, immediately initiate a direct thrombin inhibitor, subsequently confirm the diagnosis with specific laboratory assays, and finally transition to warfarin only after platelet count recovery.

The definitive management sequence for high-probability heparin-induced thrombocytopenia (HIT) prioritizes immediate cessation of heparin and prompt initiation of a non-heparin anticoagulant (such as a direct thrombin inhibitor) to prevent catastrophic thrombosis. Diagnostic confirmation follows empirically initiated therapy. Warfarin is delayed until the platelet count normalizes.

Step-by-Step Solution

Discontinue all heparin products

Halts ongoing immune complex formation

Heparin removal is required to stop the generation of PF4-heparin-IgG complexes.

Start a non-heparin anticoagulant

Provides safe and necessary anticoagulation

The patient has a new DVT and is at high risk for further thrombosis; empiric treatment cannot be delayed.

Perform confirmatory diagnostic testing

Provides a definitive diagnosis of HIT

The serotonin release assay confirms the diagnosis while the patient is safely maintained on an alternative anticoagulant.

Transition to oral warfarin

Establishes long-term outpatient anticoagulation

Bridging to warfarin can only be done safely once platelets are >150,000/mm³ to avoid a severe hypercoagulable state.

Key Concept

Management algorithm for Heparin-Induced Thrombocytopenia (HIT)

Question 1618Question →

A 67-year-old male is brought to the emergency department by his daughter due to a three-day history of progressively worsening shortness of breath. The patient reports that his typical morning cough has worsened, producing a larger volume of thick, yellowish-green sputum. His past medical history is significant for chronic obstructive pulmonary disease and hypertension. Current vital signs reveal a temperature of 37.3°C (99.1°F), blood pressure of 138/86 mm Hg, heart rate of 98/min, and a respiratory rate of 22/min. Pulse oximetry shows an oxygen saturation of 91% on ambient air. Physical examination demonstrates a prolonged expiratory phase with diffuse bilateral wheezing. There is no jugular venous distention, and the lower extremities are free of edema. Which of the following interventions are indicated in the initial management of this patient's current condition? (Select all that apply.)

Select all that apply

Nebulized albuterol and ipratropium

Oral prednisone

Intravenous furosemide

Intravenous piperacillin-tazobactam

Intravenous sodium bicarbonate

Show answer & explanation

Answer: Nebulized albuterol and ipratropium; Oral prednisone

Answer

The correct interventions are nebulized albuterol and ipratropium, and oral prednisone.

The patient is experiencing an acute exacerbation of chronic obstructive pulmonary disease, characterized by an acute worsening of respiratory symptoms including increased dyspnea, sputum volume, and sputum purulence. The standard initial management for this condition includes the administration of short-acting bronchodilators (such as albuterol and ipratropium) to relieve acute bronchospasm and systemic corticosteroids (such as oral prednisone) to decrease airway inflammation and improve recovery time. Although this patient also requires antibiotics due to having all three cardinal symptoms, a standard macrolide or aminopenicillin is indicated rather than broad-spectrum intravenous coverage.

Step-by-Step Solution

Evaluate the patient's clinical presentation.

The patient has worsening dyspnea, increased sputum volume, and increased sputum purulence.

These are the cardinal symptoms of an acute exacerbation of chronic obstructive pulmonary disease.

Determine the appropriate initial pharmacological therapy.

Short-acting bronchodilators and systemic corticosteroids should be administered.

These medications reduce airway resistance, decrease inflammation, and improve lung function in acute exacerbations.

Key Concept

The initial management of an acute exacerbation of chronic obstructive pulmonary disease requires short-acting bronchodilators and systemic corticosteroids.

Question 1619Question →

Match the following thoracic trauma clinical presentations to their most appropriate immediate next step in management or diagnostic evaluation.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Penetrating trauma with Beck's triad pairs with Pericardial window. Tension pneumothorax pairs with Tube thoracostomy. Widened mediastinum pairs with CT angiography. Flail chest pairs with Epidural analgesia.

Each clinical presentation describes a classic thoracic trauma scenario requiring a specific intervention as per Advanced Trauma Life Support (ATLS) guidelines. Cardiac tamponade requires surgical decompression. Tension pneumothorax requires immediate clinical decompression. Suspected aortic injury requires CT angiography. Flail chest requires aggressive pain control to ensure adequate mechanics of breathing.

Step-by-Step Solution

Analyze the first presentation: left parasternal penetrating injury with hypotension, muffled heart sounds, and jugular venous distention.

Identified as cardiac tamponade.

Blood accumulating in the pericardial sac restricts cardiac filling, causing obstructive shock (Beck's triad).

Analyze the second presentation: blunt trauma with respiratory distress, unilateral absent breath sounds, and hypotension.

Identified as a tension pneumothorax.

Intrathoracic pressure build-up collapses the lung and impedes venous return, requiring immediate decompression.

Analyze the third presentation: high-speed deceleration with a widened mediastinum.

Identified as a suspected blunt thoracic aortic injury.

Deceleration forces can tear the aorta at the ligamentum arteriosum, requiring CT angiography for definitive diagnosis.

Analyze the fourth presentation: blunt trauma with paradoxical chest wall movement.

Identified as flail chest.

Multiple contiguous rib fractures create a floating segment. Management focuses on pulmonary hygiene and pain control to prevent atelectasis and pneumonia.

Key Concept

Identification and appropriate initial management of life-threatening thoracic trauma, including cardiac tamponade, tension pneumothorax, blunt aortic injury, and flail chest.

Question 1620Question →

A 9-month-old boy is brought to the pediatric clinic by his parents due to progressive lethargy, poor feeding, and loss of motor milestones over the past two months. Previously, he was able to sit without support, but he now has pronounced head lag and generalized weakness. Physical examination reveals a pale, apathetic infant with generalized hypotonia and a smooth, erythematous tongue. There is no hepatosplenomegaly, and no dysmorphic facial features are noted.

Laboratory studies are obtained and reveal the following:

Laboratory Test	Result	Reference Range
Hemoglobin	8.2 g/dL	10.5–13.5 g/dL
Mean corpuscular volume	108 fL	70–86 fL
Reticulocyte count	0.5%	0.5–1.5%
Vitamin B12 (cobalamin)	450 pg/mL	160–950 pg/mL
Folate	12 ng/mL	2.5–20.0 ng/mL
Homocysteine	85 µmol/L	5–15 µmol/L
Methylmalonic acid	14.2 µmol/L	0.0–0.4 µmol/L

Which of the following is the most likely primary underlying defect in this patient?

Impaired intracellular reduction and processing of cobalamin

Absent activity of methylmalonyl-CoA mutase

Decreased activity of cystathionine beta-synthase

Defective production of gastric intrinsic factor

Decreased activity of methylenetetrahydrofolate reductase

Show answer & explanation

Answer: Impaired intracellular reduction and processing of cobalamin

Answer

The most likely underlying cause is an impaired intracellular reduction and processing of cobalamin, which prevents the formation of both active vitamin B12 coenzymes despite adequate serum B12 levels.

The correct answer describes a defect in the intracellular processing of vitamin B12 (cobalamin). Once vitamin B12 enters the target cells, it must be chemically reduced and processed to form two active coenzymes: methylcobalamin (required by methionine synthase to convert homocysteine to methionine) and adenosylcobalamin (required by methylmalonyl-CoA mutase to convert methylmalonyl-CoA to succinyl-CoA). An intracellular processing defect (such as cblC disease) prevents the synthesis of both coenzymes. This results in the accumulation of both homocysteine and methylmalonic acid, causing severe developmental regression, hypotonia, and megaloblastic anemia, even though the serum concentration of vitamin B12 is completely normal.

Step-by-Step Solution

Analyze the complete blood count (CBC) and reticulocyte count.

The patient has a macrocytic anemia (high MCV, low hemoglobin) with an inappropriately low reticulocyte count, suggesting a megaloblastic process (typically folate or B12 dysfunction).

Identifying the mechanism of anemia narrows the differential to DNA synthesis defects, primarily involving the folate/B12 pathways.

Evaluate the serum vitamin levels.

Both serum vitamin B12 and folate levels are well within the normal reference ranges.

Normal serum levels rule out simple dietary deficiency, malabsorption (e.g., intrinsic factor deficiency), or transport defects in the gastrointestinal tract.

Interpret the specialized metabolic markers (homocysteine and methylmalonic acid).

Both plasma homocysteine and serum methylmalonic acid (MMA) are significantly elevated.

Elevated homocysteine indicates impaired methionine synthase activity (which requires methylcobalamin). Elevated MMA indicates impaired methylmalonyl-CoA mutase activity (which requires adenosylcobalamin).

Synthesize the biochemical data to identify the exact enzymatic block.

A defect upstream of both the methylcobalamin and adenosylcobalamin synthesis pathways is present inside the cell, despite adequate cobalamin in the blood.

This isolates the pathology to an intracellular cobalamin processing defect (most commonly the MMACHC gene mutation causing cblC disease), which presents in infancy with regression, hypotonia, and combined MMA/homocystinemia.

Key Concept

Intracellular cobalamin metabolism defects (e.g., cblC disease)

PreviousPage 81 / 414Next

All practice questions

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept