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Difficulty: Very hardPulmonary and Critical Care

A 7171-year-old man is brought to the emergency department by emergency medical services due to severe shortness of breath and confusion. His wife reports that he has had a productive cough with thick, greenish sputum and subjective fevers for the past three days. His medical history is significant for severe chronic obstructive pulmonary disease (FEV1 30%30\% of predicted) and ischemic cardiomyopathy (left ventricular ejection fraction 35%35\%).

Upon arrival, his temperature is 38.8∘C38.8^\circ\text{C} (101.8∘F101.8^\circ\text{F}), blood pressure is 82/48 mm Hg82/48\text{ mm Hg}, pulse is 128/min128/\text{min}, and respiratory rate is 36/min36/\text{min}. Oxygen saturation is 81%81\% on room air. Physical examination reveals a lethargic, confused patient using accessory muscles of respiration. The jugular venous pulsation is visible 4 cm4\text{ cm} above the sternal angle. Lung auscultation reveals diffuse expiratory wheezes and coarse crackles over the right lower lung field. The extremities are exceptionally warm, and peripheral pulses are bounding.

Arterial blood gas analysis on room air reveals:
pH: 7.127.12
PaCO 2_2: 58 mm Hg58\text{ mm Hg}
PaO 2_2: 48 mm Hg48\text{ mm Hg}
HCO 3−_3^-: 18 mEq/L18\text{ mEq/L}

Which of the following initial interventions are indicated in the management of this patient? (Select all that apply)

  1. Endotracheal intubation and mechanical ventilationAnswer
  2. Administration of intravenous piperacillin-tazobactamAnswer
  3. C
    Initiation of a continuous intravenous furosemide infusion
  4. D
    Administration of an intravenous sodium bicarbonate bolus
  5. E
    Initiation of empiric therapy with intravenous ceftriaxone monotherapy

Answer

The correct initial interventions are endotracheal intubation with mechanical ventilation and the administration of intravenous piperacillin-tazobactam.
The correct interventions address the patient's critical respiratory and infectious issues simultaneously. The patient has severe hypercapnic and hypoxemic respiratory failure with altered mental status and hemodynamic instability, which are absolute contraindications to noninvasive positive-pressure ventilation (NIPPV). Invasive mechanical ventilation via endotracheal intubation is required to secure the airway and correct the ventilatory failure. Concurrently, broad-spectrum antibiotics with antipseudomonal coverage, such as piperacillin-tazobactam, are indicated because he has a severe COPD exacerbation with suspected pneumonia and septic shock, placing him at high risk for Pseudomonas aeruginosa.

Step-by-Step Solution

1
Evaluate the patient's hemodynamic status and tissue perfusion.
The patient is in distributive (septic) shock.
Hypotension, tachycardia, fever, and warm extremities with bounding pulses point to sepsis rather than cardiogenic shock, despite his history of heart failure.
2
Analyze the arterial blood gas results to determine the primary and secondary acid-base disorders.
The patient has a mixed metabolic acidosis and severe respiratory acidosis.
Winter's formula predicts an expected PaCO2 of 35±2 mm Hg35 \pm 2\text{ mm Hg} (1.5×18+81.5 \times 18 + 8). The actual PaCO2 is 58 mm Hg58\text{ mm Hg}, indicating concomitant ventilatory failure.
3
Determine the appropriate airway and ventilatory management.
Endotracheal intubation and invasive mechanical ventilation are required.
The patient has severe mixed acidemia, hypoxemia, altered mental status, and hemodynamic instability, which are absolute contraindications to noninvasive ventilation.
4
Select the appropriate empiric antibiotic regimen for a critically ill patient with severe COPD.
Initiate intravenous piperacillin-tazobactam.
The patient is at high risk for Pseudomonas aeruginosa due to severe COPD and critical illness requiring ICU admission; therefore, antipseudomonal coverage is mandatory.

Key Concept

Management of severe mixed respiratory and metabolic acidosis complicated by septic shock in a patient with advanced chronic obstructive pulmonary disease.
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Topics

Pulmonary and Critical Care

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