Internal Medicine

Select the most appropriate first-line antimicrobial therapy for each of the following patients presenting with a characteristic infectious syndrome.

An emergency medical services team brings a 58-year-old man to the hospital due to severe, continuous substernal chest pain, shortness of breath, and profound diaphoresis that began 45 minutes ago. His medical history is significant for hyperlipidemia and a 35-pack-year smoking habit. Initial vital signs demonstrate a blood pressure of $85/50\text{ mmHg}$, a heart rate of $55/\text{min}$, and a respiratory rate of $20/\text{min}$. Physical examination reveals significantly elevated jugular venous pressure, but the lung fields are completely clear to auscultation bilaterally. A 12-lead electrocardiogram demonstrates $3\text{ mm}$ ST-segment elevations in leads II, III, and aVF. Which of the following is the most appropriate next step in the management of this patient's hypotension?

A 22-year-old woman with a history of bulimia nervosa and type 1 diabetes mellitus is brought to the emergency department by her roommate due to severe lethargy and confusion. The roommate reports that the patient has been intentionally restricting her insulin doses and has been vomiting frequently over the past 3 days. Temperature is 37.0°C (98.6°F), blood pressure is 100/60 mmHg, pulse is 118/min, and respirations are 24/min.

Laboratory studies show:

Arterial blood gas on room air:

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

A $29$-year-old man is evaluated in the hospital for worsening bloody diarrhea and abdominal pain. He was admitted $5$ days ago for a severe exacerbation of ulcerative pancolitis, presenting at that time with $12$ bloody bowel movements daily, severe cramps, and a weight loss of $4.5\text{ kg}$ ($10\text{ lbs}$). On admission, stool studies were negative for Clostridioides difficile toxin, Salmonella, Shigella, and Campylobacter. He was subsequently started on high-dose intravenous methylprednisolone.

Despite $5$ days of corticosteroid therapy, the patient's symptoms have rapidly deteriorated. He now reports $15$ bloody bowel movements a day and new-onset subjective fevers. His temperature is $38.6^{\circ}\text{C}$ ($101.5^{\circ}\text{F}$), blood pressure is $108/68\text{ mmHg}$, and pulse is $114/\text{min}$. Physical examination reveals a distended abdomen with diffuse tenderness, but no rebound or guarding is present.

Laboratory studies show:
Hemoglobin: $7.8\text{ g/dL}$
Leukocyte count: $14,500/\text{mm}^3$
Erythrocyte sedimentation rate: $72\text{ mm/hr}$

An unprepared flexible sigmoidoscopy reveals diffuse mucosal erythema, friability, and several large, deep, punched-out ulcers in the descending colon. Histopathologic examination of the ulcer base biopsies demonstrates cytomegaly with prominent eosinophilic intranuclear inclusions surrounded by a clear halo.

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

A 72-year-old woman is admitted to the intensive care unit with a temperature of 39.2°C (102.6°F), severe right upper quadrant abdominal pain, and new-onset confusion. Her blood pressure is 88/54 mmHg, and her heart rate is 112/min. Physical examination is notable for marked scleral icterus and right upper quadrant tenderness with guarding.

A bedside ultrasound shows a dilated common bile duct of 14 mm and an obstructive echogenic stone. She receives aggressive intravenous fluid resuscitation and is empirically started on broad-spectrum coverage with intravenous piperacillin-tazobactam. An emergent endoscopic retrograde cholangiopancreatography (ERCP) is performed, which successfully extracts the stone and drains purulent bile.

On hospital day 3, the patient is hemodynamically stable, alert, and afebrile. She is tolerating an oral diet. Blood cultures obtained at admission return positive for a single organism. The susceptibility report is as follows:

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

A 52-year-old man with a history of severe alcohol use disorder is brought to the emergency department after being found unresponsive by his landlord. The landlord reports that the patient had been complaining of severe, intractable vomiting for the preceding three days and was unable to keep any fluids down. On physical examination, the patient appears lethargic and has remarkably dry mucous membranes with delayed capillary refill. Vital signs show a temperature of $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure of $88/55\text{ mm Hg}$, pulse of $118/\text{min}$, and respiratory rate of $10/\text{min}$.

Laboratory studies reveal the following:

Serum sodium: $136\text{ mEq/L}$
Serum potassium: $3.1\text{ mEq/L}$
Serum chloride: $82\text{ mEq/L}$
Serum bicarbonate: $13\text{ mEq/L}$
Blood urea nitrogen: $68\text{ mg/dL}$
Serum creatinine: $3.4\text{ mg/dL}$ (baseline $1.1\text{ mg/dL}$)

Arterial blood gas (room air):
pH: $7.16$
$PaCO_2$: $38\text{ mm Hg}$
$PaO_2$: $68\text{ mm Hg}$

Based on the provided laboratory results, which of the following best characterizes the complete set of primary acid-base abnormalities present in this patient?

Match each patient's clinical presentation and peripheral blood smear findings with the most likely underlying hematologic diagnosis.

A $65$-year-old man is evaluated on the medical ward for persistent fatigue and generalized weakness. He was admitted $3$ weeks ago for severe pneumococcal pneumonia complicated by acute respiratory distress syndrome (ARDS) and septic shock, requiring $14$ days of mechanical ventilation and vasopressor support. He has been extubated for $5$ days and is currently hemodynamically stable. He has no prior history of thyroid disease. His vital signs are temperature $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure $118/74 \text{ mmHg}$, pulse $82/\text{min}$, and respirations $16/\text{min}$. Physical examination reveals generalized muscle wasting but is otherwise unremarkable. The thyroid gland is not palpable.

Laboratory studies:
Hemoglobin: $10.5 \text{ g/dL}$
Leukocytes: $8,500/\text{mm}^3$
TSH: $11.4 \text{ mU/L}$ (Normal: $0.4 - 4.2 \text{ mU/L}$)
Free T4: $1.0 \text{ ng/dL}$ (Normal: $0.9 - 1.7 \text{ ng/dL}$)
Total T3: $68 \text{ ng/dL}$ (Normal: $80 - 200 \text{ ng/dL}$)

Which of the following is the most appropriate next step in management regarding the patient's thyroid laboratory abnormalities?

A 68-year-old woman is evaluated in the intensive care unit on day 4 of her admission for severe urosepsis. She initially required mechanical ventilation and high-dose vasopressor support, but her clinical status has significantly improved over the past 24 hours. She was successfully extubated yesterday, and all vasoactive infusions were discontinued this morning. Her current temperature is $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), blood pressure is $112/68\text{ mmHg}$, pulse is $84/\text{min}$, and respirations are $16/\text{min}$. Physical examination reveals a tired-appearing but alert patient. The thyroid gland is not palpable, and there is no cervical lymphadenopathy. Neurologic examination shows normal deep tendon reflexes with a normal relaxation phase. A comprehensive metabolic evaluation ordered during morning rounds shows the following results:

Which of the following is the most appropriate next step in management regarding these laboratory findings?

During a routine follow-up appointment, a $65$-year-old female patient complains of increasing difficulty breathing over the last $5$ days. She notes that she can no longer sleep in her bed and has spent the last two nights in a reclining chair. Her medical history includes long-standing hypertension, stable angina, and type 2 diabetes mellitus. She denies any fever, productive sputum, or recent sick contacts. Vital signs reveal a blood pressure of $162/88\text{ mm Hg}$, a heart rate of $95\text{/min}$, and a respiratory rate of $22\text{/min}$. Oxygen saturation is $93\%$ on ambient air. Cardiovascular examination demonstrates elevated jugular venous pressure and an audible S3 gallop. Pulmonary auscultation reveals crackles at the bases of both lungs. Examination of the lower extremities shows significant $2+$ bilateral pitting edema. Laboratory testing is notable for a B-type natriuretic peptide (BNP) level of $920\text{ pg/mL}$, a normal leukocyte count, and normal thyroid-stimulating hormone (TSH) and free T4 levels. An arterial blood gas shows a pH of $7.43$, $\text{pCO}_2$ of $34\text{ mm Hg}$, and $\text{pO}_2$ of $72\text{ mm Hg}$. Which of the following is the most appropriate next step in the pharmacologic management of this patient?

A 34-year-old woman is brought to the emergency department by her partner due to worsening confusion and lethargy over the past 48 hours. She has also complained of generalized weakness and passing dark urine. Her medical history is unremarkable, and she takes no medications. Her temperature is 38.2°C (100.8°F), blood pressure is 142/88 mmHg, pulse is 105/min, and respirations are 18/min. Physical examination reveals a drowsy but rousable patient who is oriented only to person. Pale conjunctivae and scattered petechiae are noted on the lower extremities. There are no focal motor or sensory deficits.

Laboratory studies show the following:

A peripheral blood smear demonstrates numerous fragmented red blood cells. Which of the following is the most appropriate next step in the management of this patient?

A 68-year-old man comes to the clinic reporting the onset of frequent, watery, non-bloody diarrhea occurring up to $7$ times daily over the past $3$ days. He also notes mild, diffuse lower abdominal cramping. His medical history is significant for hypertension and hyperlipidemia. Two weeks ago, he completed a 10-day course of oral amoxicillin-clavulanate for acute bacterial sinusitis. His temperature is $38.1^\circ\text{C}$ ($100.6^\circ\text{F}$), blood pressure is $118/76 \text{ mmHg}$, and heart rate is $92/\text{min}$. Physical examination reveals mild diffuse abdominal tenderness with normal bowel sounds; there is no guarding or rebound tenderness. Laboratory testing shows a leukocyte count of $14,500/\text{mm}^3$ and a serum creatinine of $1.1 \text{ mg/dL}$ (baseline $1.0 \text{ mg/dL}$). A stool nucleic acid amplification test is positive for *Clostridioides difficile* toxin genes. Which of the following is the most appropriate next step in management?

A 52-year-old man is admitted to the intensive care unit with acute severe gallstone pancreatitis. Over the course of a prolonged 6-week hospitalization, his condition requires dynamic management of evolving complications. According to current evidence-based guidelines, arrange the following clinical management steps in the correct chronological order from the initial presentation to the definitive management of late complications.

A 21-year-old woman is brought to the emergency department by her college roommate due to confusion, nausea, and ringing in her ears for the past 6 hours. The roommate reports that the patient was distraught over a recent breakup and may have ingested "a bottle of pills." On physical examination, her temperature is 38.0°C (100.4°F), blood pressure is 115/75 mm Hg, pulse is 112/min, and respiratory rate is 28/min. The patient appears flushed and is breathing deeply and rapidly. Lungs are clear to auscultation bilaterally. Laboratory results show:

Serum sodium: 140 mEq/L
Serum potassium: 3.6 mEq/L
Serum chloride: 102 mEq/L
Serum bicarbonate: 16 mEq/L
Blood urea nitrogen: 14 mg/dL
Serum creatinine: 0.8 mg/dL

Arterial blood gas (room air):
pH: 7.48
$PaCO_2$: 22 mm Hg
$PaO_2$: 100 mm Hg

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

A patient in his mid-forties is evaluated in the gastroenterology outpatient clinic due to chronic, high-volume watery diarrhea and persistent burning epigastric pain. His symptoms have been refractory to high-dose omeprazole therapy over the past six months. An upper gastrointestinal endoscopy performed recently revealed thickened gastric folds, multiple ulcerations in the descending duodenum, and an additional solitary ulcer in the proximal jejunum. Rapid urease testing and histology for Helicobacter pylori were negative. The physician strongly suspects a neuroendocrine etiology. Arrange the following diagnostic and therapeutic steps in the most appropriate chronological order for evaluating and managing this patient's suspected condition.

A physician evaluates a 71-year-old retired mechanic who reports worsening shortness of breath over the past week. He states that he frequently wakes up in the middle of the night feeling as though he is suffocating and has resorted to sleeping in a reclining chair. His medical history includes hypertension, hyperlipidemia, and a 40-pack-year smoking history. Current medications include lisinopril and atorvastatin. His blood pressure is 158/92 mmHg, pulse is 98/min, and respiratory rate is 22/min. Physical examination demonstrates distended neck veins when positioned at 45 degrees. Lung auscultation reveals bilateral crackles at the bases and scattered expiratory wheezes. Cardiac auscultation reveals a regular rhythm with a low-frequency diastolic sound heard just after S2 at the apex. Bilateral 2+ pitting edema is present in the lower extremities. Which of the following is the most likely primary pathophysiologic mechanism responsible for this patient's current symptoms?

A physician evaluates a $78$-year-old man in the emergency department for sudden-onset, excruciating abdominal pain that began $2$ hours ago. The patient reports one episode of non-bloody emesis. His medical history includes hypertension, diet-controlled type 2 diabetes mellitus, and atrial fibrillation, for which he has been nonadherent to his oral anticoagulant medication for the past several months. Vital signs reveal a temperature of $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), an irregularly irregular heart rate of $122/\text{min}$, a respiratory rate of $22/\text{min}$, and a blood pressure of $105/65\text{ mm Hg}$. On physical examination, the abdomen is soft and non-distended; there is mild, diffuse tenderness to deep palpation, but no guarding or rebound tenderness is elicited. Bowel sounds are hypoactive. Laboratory studies show a leukocyte count of $17,500/\text{mm}^3$ and a markedly elevated serum lactate level of $5.6\text{ mmol/L}$. Which of the following is the most appropriate next step in the management of this patient?

A 74-year-old man is brought to the emergency department from a skilled nursing facility due to severe abdominal pain, bloody diarrhea, and altered mental status. His medical history includes peripheral artery disease, hypertension, and a myocardial infarction one year ago. His temperature is 37.8°C (100.0°F), pulse is 118/min, blood pressure is 88/50 mm Hg, and respirations are 28/min. Physical examination shows a lethargic patient taking shallow, rapid breaths. The abdomen is distended and diffusely tender with involuntary guarding.

The following laboratory results are obtained:

Arterial blood gas analysis on room air reveals:

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

A 50-year-old man is evaluated in the neuro-intensive care unit. He was admitted four days ago after sustaining a severe closed head injury in a high-speed motor vehicle collision. Over the past 24 hours, the nursing staff reports a dramatic increase in his urine output, totaling 7.5 L of pale, dilute urine. He is currently intubated and sedated. His weight on admission was 72 kg, and his current weight is 70 kg. Vital signs show a blood pressure of 102/64 mm Hg and a heart rate of 118/min. Laboratory studies reveal a serum sodium concentration of 160 mEq/L and a serum osmolality of 330 mOsm/kg $H_2O$. Urine osmolality is 115 mOsm/kg $H_2O$. The patient is diagnosed with central diabetes insipidus.

What is this patient's estimated free water deficit in liters?

A 54-year-old man with a history of poorly controlled HIV (most recent CD4 count 112 cells/mm³) is brought to the emergency department by his partner due to fever, severe headache, and confusion over the past 24 hours. His temperature is 39.1°C (102.4°F), blood pressure is 110/70 mm Hg, pulse is 112/min, and respiratory rate is 18/min. Physical examination reveals nuchal rigidity and a new right-sided pronator drift. The physician suspects acute bacterial meningitis. Arrange the following steps in the most appropriate chronological sequence for the management of this patient.