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Difficulty: MediumPulmonary and Critical Care

A 59-year-old woman is evaluated on hospital day 3 for new-onset respiratory distress. She was initially admitted for pyelonephritis complicated by septic shock and received 4 liters of intravenous crystalloid fluids over the first 24 hours. Blood cultures drawn on admission grew *Escherichia coli* that is susceptible to ceftriaxone, ciprofloxacin, and ampicillin. She has a history of type 2 diabetes mellitus and hypertension. Current medications include intravenous piperacillin-tazobactam.

Temperature is 37.2°C (99.0°F), blood pressure is 142/86 mmHg, heart rate is 112/min, and respiratory rate is 28/min. Pulse oximetry is 88% on room air. Physical examination reveals jugular venous distention to 11 cm H2O. Lung auscultation demonstrates bilateral crackles extending to the mid-scapulae and diffuse expiratory wheezes.

Arterial blood gas analysis on room air reveals:
pH: 7.25
PaCO2: 42 mmHg
PaO2: 56 mmHg
HCO3-: 18 mEq/L

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

  1. Intravenous furosemide and noninvasive positive pressure ventilationAnswer
  2. B
    Inhaled albuterol and intravenous methylprednisolone
  3. C
    Escalation of antimicrobial therapy to intravenous meropenem
  4. D
    Intravenous sodium bicarbonate infusion
  5. E
    Intravenous normal saline bolus and transition to ceftriaxone

Answer

Intravenous furosemide and noninvasive positive pressure ventilation
The correct answer combines intravenous furosemide and noninvasive positive pressure ventilation (NPPV). This patient developed acute decompensated heart failure (ADHF) secondary to aggressive fluid resuscitation for sepsis. Clinical signs include elevated jugular venous pressure, bibasilar crackles, and hypoxemia. The wheezing represents 'cardiac asthma' resulting from peribronchial edema. The ABG demonstrates a primary metabolic acidosis (HCO3−HCO_3^- of 18 mEq/L18\ mEq/L). According to Winter's formula (Expected PaCO2=1.5×18+8=35±2 mmHgExpected\ PaCO_2 = 1.5 \times 18 + 8 = 35 \pm 2\ mmHg), the PaCO2PaCO_2 should be between 3333 and 37 mmHg37\ mmHg. Her actual PaCO2PaCO_2 is 42 mmHg42\ mmHg, which indicates a superimposed respiratory acidosis due to respiratory muscle fatigue from the severe pulmonary edema. Immediate treatment requires diuresis to reduce volume status and NPPV to offload the work of breathing and improve gas exchange.

Step-by-Step Solution

1
Analyze the physical examination findings and clinical history.
The patient has elevated jugular venous distention, bilateral crackles, and wheezing following large-volume fluid resuscitation, indicating volume overload and acute pulmonary edema.
Differentiating iatrogenic volume overload from progression of sepsis or primary pulmonary disease is the first step in diagnosing her acute deterioration.
2
Interpret the arterial blood gas (ABG) using Winter's formula.
The patient has a primary metabolic acidosis (HCO3−HCO_3^- = 18 mEq/L). Using Winter's formula (1.5×18+8=35±21.5 \times 18 + 8 = 35 \pm 2), the expected PaCO2PaCO_2 is 33-37 mmHg. The actual PaCO2PaCO_2 is 42 mmHg.
Calculating expected respiratory compensation reveals a superimposed, uncompensated respiratory acidosis, indicating the patient is developing respiratory muscle fatigue.
3
Determine the most appropriate management.
The combination of diuresis (furosemide) and noninvasive positive pressure ventilation (NPPV) is selected.
Furosemide reduces total body volume, while NPPV decreases the work of breathing, improves oxygenation, and decreases cardiac preload, addressing both the fluid overload and the impending respiratory failure.

Key Concept

Recognition of iatrogenic volume overload causing acute decompensated heart failure and a mixed acid-base disorder, requiring diuresis and ventilatory support.
Estimated Time:1m 30s
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Topics

Pulmonary and Critical Care

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