A 71-year-old woman is evaluated in the intensive care unit for persistent respiratory dis… — USMLE Step 2 CK

A 71-year-old woman is evaluated in the intensive care unit for persistent respiratory distress and hypotension. She was intubated earlier today for severe hypoxemic respiratory failure. Her past medical history includes severe chronic obstructive pulmonary disease ( $\text{FEV}_1$ $35\%$ of predicted) and a prior anterior myocardial infarction. Current vital signs show a temperature of $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), heart rate of $115\text{ /min}$ , blood pressure of $86/54\text{ mmHg}$ , and oxygen saturation of $94\%$ on mechanical ventilation. Physical examination reveals diffuse bilateral wheezing. A pulmonary artery catheter reveals the following hemodynamic measurements:

* Right atrial pressure: $15\text{ mmHg}$
* Pulmonary artery pressure: $58/32\text{ mmHg}$
* Pulmonary capillary wedge pressure: $28\text{ mmHg}$
* Cardiac index: $1.7\text{ L/min/m}^2$

Based on these findings, which of the following is the most appropriate next step in pharmacological management?

Intravenous dobutamineAnswer
B
Intravenous methylprednisolone
C
Intravenous normal saline bolus
D
Inhaled nitric oxide
E
Intravenous metoprolol

Answer

Intravenous dobutamine

The correct answer identifies that the patient is in cardiogenic shock, characterized by hypotension, a severely reduced cardiac index, and an elevated pulmonary capillary wedge pressure (PCWP). The elevated PCWP (>18 mm Hg) confirms that the primary pathology is acute decompensated left heart failure, and the wheezing ("cardiac asthma") is secondary to pulmonary edema, not primarily a chronic obstructive pulmonary disease (COPD) exacerbation. The most appropriate next step is initiating an inotrope, such as dobutamine, to improve myocardial contractility, increase cardiac output, and maintain systemic perfusion.

Step-by-Step Solution

Analyze patient's clinical presentation.

Hypotension, tachycardia, and respiratory failure with wheezing in a patient with a history of myocardial infarction and COPD.

To form a differential diagnosis for mixed presentation of shock and respiratory failure.

Interpret hemodynamic data from the pulmonary artery catheter.

PCWP is extremely elevated (

28\text{ mmHg}

), confirming left-sided volume overload.

To differentiate between cardiogenic causes (high PCWP) and primary pulmonary/right heart causes (normal or low PCWP).

Evaluate cardiac output and systemic perfusion.

Severely reduced cardiac index (

1.7\text{ L/min/m}^2

) combined with hypotension confirms cardiogenic shock.

To determine the severity of pump failure and the physiological need for inotropic support.

Determine the most appropriate pharmacological management.

Intravenous dobutamine is indicated.

Inotropes improve forward flow, increase cardiac output, and reduce pulmonary congestion in cardiogenic shock.

Key Concept

Differentiation of shock etiologies using pulmonary artery catheter hemodynamics and management of cardiogenic shock.

Estimated Time:2m 0s

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