Internal Medicine

A previously healthy female collegiate athlete is admitted to the medical intensive care unit shortly after collapsing at the finish line of a summer half-marathon. Emergency medical personnel found her lethargic and disoriented. On arrival, her temperature is 39.4 °C (102.9 °F), blood pressure is 88/54 mm Hg, heart rate is 132/min, and respiratory rate is 26/min. Physical examination reveals dry mucous membranes and diffuse muscle tenderness, but lungs are clear to auscultation.

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

A $34$-year-old woman with a history of type $1$ diabetes mellitus is brought to the emergency department due to severe nausea, diffuse abdominal pain, and intractable vomiting for the past $48$ hours. She reports missing her last three doses of insulin because she was unable to tolerate any oral intake. On physical examination, her blood pressure is $98/60\text{ mm Hg}$, heart rate is $118\text{ /min}$, and respiratory rate is $22\text{ /min}$. Her mucous membranes are remarkably dry, and skin turgor is decreased.

Laboratory testing reveals:

Assuming a normal serum anion gap of $12\text{ mEq/L}$ and a normal serum bicarbonate of $24\text{ mEq/L}$, calculate the patient's delta ratio ($\frac{\Delta\text{AG}}{\Delta\text{HCO}_3^-}$) to evaluate for the presence of a mixed acid-base disorder.

A $68$-year-old retired teacher is brought to the acute care clinic by his wife due to $48$ hours of worsening breathlessness and a change in his chronic cough. He notes his sputum has become thick and yellow-green, and he is coughing up a larger volume than usual. His medical history includes moderate chronic obstructive pulmonary disease and essential hypertension. On triage, his temperature is $37.6^\circ$ C ($99.7^\circ$ F), blood pressure is $158/92$ mm Hg, pulse is $114$/min, and respiratory rate is $28$/min. Pulse oximetry shows an oxygen saturation of $85\%$ on ambient air.

Physical examination reveals a barrel-shaped chest. Lung auscultation demonstrates globally decreased breath sounds with prominent expiratory wheezing and a significantly prolonged expiratory phase. Cardiac examination reveals a regular rhythm, rapid rate, and no murmurs or gallops. The jugular veins are not distended, and there is no lower extremity edema.

An arterial blood gas analysis performed on room air demonstrates:

A portable chest radiograph shows flattened diaphragms and increased retrosternal airspace, without focal opacities or cardiomegaly.

He is immediately provided with supplemental oxygen via Venturi mask (targeting a saturation of $90\%$-$92\%$), nebulized short-acting bronchodilators, and systemic glucocorticoids.

Which of the following are appropriate additional steps in the management of this patient's acute condition? (Select $2$ answers)

A 28-year-old woman with a history of extensive ulcerative colitis is hospitalized due to a severe disease flare characterized by 12 bloody bowel movements daily, severe lower abdominal cramping, and a temperature of $38.6^\circ\text{C}$ ($101.5^\circ\text{F}$). Her heart rate is $118/\text{min}$ and blood pressure is $110/70 \text{ mm Hg}$. Arrange the following management steps in the correct chronological sequence of escalation, assuming she remains refractory to each successive medical intervention.

Evaluate the following clinical vignettes detailing patients with abnormal coagulation profiles. Match each patient presentation with the most accurate underlying pathophysiologic mechanism.

Match each clinical scenario with the primary acid-base disorder it most likely causes.

A 42-year-old man comes to the clinic complaining of a burning sensation in his chest that radiates toward his neck. He states that these symptoms occur 3 to 4 times a week and have been present for the past 2 months. The discomfort typically worsens after large meals and when lying down at night. He frequently experiences a sour taste in his mouth. He denies difficulty swallowing, pain with swallowing, unexplained weight loss, nausea, vomiting, or dark stools. His past medical history is unremarkable, and he takes no daily medications. Vital signs are within normal limits, and physical examination shows a non-tender, non-distended abdomen. Which of the following is the most appropriate next step in the management of this patient?

A 21-year-old male university student is brought to the emergency department by his roommate due to a 3-day history of progressively worsening confusion, severe fatigue, and yellowing of his skin. The roommate reports that over the past 3 months, the patient has exhibited unusual behavior, including severe paranoia and disorganized speech, which they attributed to the stress of upcoming exams. He takes no medications and does not consume alcohol or illicit drugs. His temperature is 37.0°C (98.6°F), blood pressure is 105/65 mmHg, and heart rate is 112/min. Physical examination reveals profound scleral icterus and generalized jaundice. The abdomen is distended with shifting dullness, and a firm, enlarged spleen is palpable. A coarse, "flapping" tremor is noted when the patient extends his arms and wrists.

Laboratory studies show:

Direct antiglobulin (Coombs) test is negative. Which of the following is the most appropriate next step in management for this patient?

During morning rounds on the surgical ward, a physician evaluates a 74-year-old male who developed progressive respiratory distress overnight. The patient was admitted 48 hours ago and underwent an elective total knee arthroplasty. He received 3 liters of intravenous crystalloid during the perioperative period. His past medical history includes hypertension, diet-controlled type 2 diabetes mellitus, and a 45-pack-year smoking history. Vital signs show a temperature of $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure of $172/96\text{ mmHg}$, heart rate of $108/\text{min}$, and respiratory rate of $26/\text{min}$. Pulse oximetry is $88\%$ on room air. On physical examination, the patient is sitting upright and using accessory muscles of respiration. Lung auscultation reveals diffuse expiratory wheezes and bilateral crackles extending to the mid-lung fields. The jugular veins are distended to $9\text{ cm H}_2\text{O}$ above the sternal angle. Cardiac examination demonstrates a regular, rapid rhythm with a distinct third heart sound (S3). Lower extremities show 1+ pitting edema bilaterally, which the patient states is unchanged from his preoperative baseline. Which of the following is the most appropriate next step in the management of this patient?

A 22-year-old man with type 1 diabetes mellitus presents to the emergency department with abdominal pain, nausea, and persistent vomiting for the past 2 days. He reports missing his last several doses of insulin. His vital signs include a heart rate of 118/min and a blood pressure of 90/60 mm Hg. Laboratory studies show the following:

Assuming a normal reference serum anion gap of 12 mEq/L and a normal serum bicarbonate of 24 mEq/L, what is the patient's delta ratio (calculated as the change in anion gap divided by the change in serum bicarbonate)? (Provide the exact calculated decimal value).

Match each clinical exposure scenario with the most appropriate post-exposure prophylaxis or management strategy.

A $64$-year-old man with a history of hypertension, hyperlipidemia, and a $45$-pack-year smoking history presents to the primary care clinic with a $3$-month history of a cramping ache in his left calf. The pain reliably occurs after walking approximately two city blocks and resolves completely with $5$ minutes of rest. He has no leg pain at rest and no history of foot ulcers. His blood pressure is $142/86$ mmHg, and his pulse is $76$/min. Physical examination reveals thinning of the skin and loss of hair on the distal lower extremities bilaterally. The dorsalis pedis and posterior tibial pulses are faintly palpable bilaterally.

Arrange the following management steps in the most appropriate chronological sequence for this patient, from the initial diagnostic step to the last-resort intervention.

A $68$-year-old man is evaluated on postoperative day $3$ following an uncomplicated open cholecystectomy. He reports the sudden onset of excruciating pain and swelling in his right knee that woke him from sleep early this morning. His temperature is $38.2^\circ\text{C}$ ($100.8^\circ\text{F}$), blood pressure is $135/85 \text{ mm Hg}$, and pulse is $98/\text{min}$. Medical history is significant for type 2 diabetes mellitus, hypertension, and stage 3 chronic kidney disease. Laboratory studies show a serum creatinine level of $2.2 \text{ mg/dL}$ (baseline $2.1 \text{ mg/dL}$) and a blood urea nitrogen level of $34 \text{ mg/dL}$. Physical examination reveals a warm, erythematous, exquisitely tender right knee with a visible effusion and severely limited range of motion. Arthrocentesis is performed, yielding $5 \text{ mL}$ of turbid yellow fluid. Synovial fluid analysis shows a leukocyte count of $45,000/\mu\text{L}$ with $85\%$ neutrophils. Polarized light microscopy reveals needle-shaped, negatively birefringent crystals. Gram stain shows no organisms. Which of the following is the most appropriate next step in management?

A 52-year-old woman with a history of diffuse cutaneous systemic sclerosis and major depressive disorder presents to the emergency department with acute onset of severe dyspnea, pounding headache, and blurred vision. Her medications include mycophenolate mofetil and fluoxetine. Temperature is $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure is $225/125 \text{ mm Hg}$, pulse is $112/\text{min}$, and respirations are $26/\text{min}$. Physical examination reveals jugular venous distention, bibasilar lung crackles, and an $S_3$ gallop. The skin over her chest, abdomen, and proximal extremities is markedly thickened and tight.

Laboratory studies show:

Arterial blood gas analysis on room air reveals:

A peripheral blood smear shows multiple fragmented red blood cells (schistocytes). Which of the following is the most appropriate next step in the medical management of this patient?

A $72$-year-old man is brought to the emergency department by his daughter due to two days of progressively worsening shortness of breath. He reports orthopnea and a nonproductive cough. His medical history is significant for severe chronic obstructive pulmonary disease (COPD), ischemic cardiomyopathy with a left ventricular ejection fraction of $40\%$, and benign prostatic hyperplasia. Current medications include a long-acting muscarinic antagonist, a long-acting beta-agonist, and low-dose aspirin.

Temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $162/94\text{ mm Hg}$, pulse is $115/\text{min}$, and respiratory rate is $28/\text{min}$. Pulse oximetry shows $85\%$ on room air.

Physical examination reveals an anxious man in respiratory distress using accessory muscles of respiration. The jugular venous pressure is estimated at $10\text{ cm H}_2\text{O}$. Cardiac auscultation reveals tachycardia with a regular rhythm and a distinct third heart sound (S3). Lung auscultation demonstrates diffuse expiratory wheezes bilaterally with a prolonged expiratory phase. Bilateral 1+ pitting edema is present in the lower extremities.

A chest radiograph shows cardiomegaly, prominent interstitial markings with cephalization of the pulmonary vasculature, and hyperinflated lung fields, but no focal consolidation.

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

A 68-year-old man is evaluated in the hospital for worsening shortness of breath. He was admitted 3 days ago for community-acquired pneumonia. A sputum culture obtained on admission grew *Streptococcus pneumoniae* sensitive to amoxicillin, and he has been receiving targeted oral amoxicillin therapy. Over the past 12 hours, he has become progressively dyspneic and developed swelling in his legs. Medical history is significant for hypertension, type 2 diabetes mellitus, and a 40-pack-year smoking history. The patient is alert and anxious. Temperature is 37.1°C (98.8°F), blood pressure is 156/92 mm Hg, pulse is 105/min, and respirations are 24/min. Pulse oximetry shows 89% on room air. Physical examination reveals elevated jugular venous pressure. Lung auscultation reveals prolonged expiration, scattered wheezes bilaterally, and bibasilar crackles. Cardiac examination shows regular tachycardia with a third heart sound (S3). There is 2+ bilateral pitting edema to the mid-calves.

Laboratory studies show:
- Sodium: 138 mEq/L
- Potassium: 4.2 mEq/L
- Chloride: 104 mEq/L
- Bicarbonate: 14 mEq/L
- Blood urea nitrogen: 30 mg/dL
- Serum creatinine: 1.5 mg/dL
- Lactic acid: 4.5 mmol/L (Normal: 0.5-1.0)
- Thyroid-stimulating hormone (TSH): 0.1 mU/L (Normal: 0.4-4.0)
- Free T4: 0.5 ng/dL (Normal: 0.9-2.4)

Arterial blood gas analysis on room air:
- pH: 7.28
- PaCO2: 30 mm Hg
- PaO2: 62 mm Hg

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

A 58-year-old man is hospitalized for a newly diagnosed left lower extremity deep vein thrombosis. He has a history of hypertension and type 2 diabetes mellitus. On admission (Day 1), he was started on a continuous intravenous unfractionated heparin infusion and oral warfarin.

Today (Day 6 of hospitalization), the patient complains of severe pain and dark purple discoloration over his right toes and the heel of his left foot.

Vital signs are temperature 37.0°C (98.6°F), blood pressure 135/85 mm Hg, pulse 98/min, and respirations 16/min.

Physical examination reveals well-demarcated, necrotic, purpuric lesions on the toes of the right foot and the heel of the left foot. The left leg is edematous but unchanged from admission. Peripheral pulses are palpable bilaterally.

Laboratory results are as follows:

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

A 48-year-old woman with a history of severe rheumatoid arthritis presents to the clinic with large, unexplained ecchymoses on her thighs and arms over the past two weeks. She has no prior personal or family history of bleeding disorders. Initial laboratory testing reveals an isolated, significantly prolonged activated partial thromboplastin time (aPTT) with a normal prothrombin time (PT) and normal platelet count. Arrange the following steps in the standard diagnostic algorithm used to definitively diagnose an acquired coagulation factor inhibitor in this patient in the correct chronological sequence.

Match each clinical exposure scenario with its most appropriate post-exposure prophylaxis or targeted management regimen.

A 64-year-old man with a history of metastatic prostate cancer presents to the emergency department with severe, progressively worsening mid-back pain for the past 2 weeks. Today, he developed bilateral leg weakness and urinary incontinence. Temperature is 37.1°C (98.8°F), blood pressure is 145/90 mmHg, pulse is 92/min, and respiratory rate is 16/min. Physical examination reveals 3/5 motor strength in both lower extremities, decreased pinprick sensation below the T10 dermatome, and hyperreflexia at the knees. Anal sphincter tone is decreased. Laboratory results show a hemoglobin of 11.2 g/dL, leukocyte count of 7,500/μL, platelet count of 210,000/μL, serum creatinine of 1.1 mg/dL, and serum calcium of 9.8 mg/dL. Suspecting a neurologic emergency, arrange the following management steps in the most appropriate chronological order from first to last to optimize his neurologic outcome.