A 72-year-old man is evaluated in the surgical intensive care unit for worsening shortness… — USMLE Step 2 CK

A $72$ -year-old man is evaluated in the surgical intensive care unit for worsening shortness of breath, altered mental status, and hypotension. He was admitted $4$ days ago for an emergency exploratory laparotomy due to a perforated gastric ulcer. His medical history includes heart failure with preserved ejection fraction and severe chronic obstructive pulmonary disease. Temperature is $38.9^\circ \text{C}$ ( $102.0^\circ \text{F}$ ), blood pressure is $80/48 \text{ mm Hg}$ , pulse is $128/\text{min}$ , and respirations are $28/\text{min}$ . Oxygen saturation is $88\%$ on room air. Physical examination reveals a lethargic patient with warm, well-perfused extremities. Lung auscultation reveals coarse crackles and bronchial breath sounds over the right lower lung field. Cardiac examination shows tachycardia with a regular rhythm and no murmurs. Laboratory studies show a leukocyte count of $18,500/\text{mm}^3$ and a serum lactate of $4.2 \text{ mmol/L}$ . Arterial blood gas analysis on room air reveals:

pH: $7.25$
$\text{PaCO}_2$ : $28 \text{ mm Hg}$
$\text{PaO}_2$ : $56 \text{ mm Hg}$
$\text{HCO}_3^-$ : $12 \text{ mEq/L}$

Which of the following are the most appropriate immediate steps in the management of this patient? (Select all that apply)

Rapid infusion of intravenous crystalloid solutionAnswer
Administration of intravenous cefepime and vancomycinAnswer
C
Initiation of noninvasive positive pressure ventilation to normalize arterial carbon dioxide tension
D
Administration of intravenous bumetanide
E
Lower extremity venous duplex ultrasonography

Answer

The most appropriate immediate steps in management are rapid infusion of intravenous crystalloid solution and administration of broad-spectrum antibiotics such as intravenous cefepime and vancomycin.

This patient presents with signs of hospital-acquired pneumonia (fever, lung consolidation, leukocytosis on postoperative day

4

) complicated by septic shock, as evidenced by hypotension with warm extremities, tachycardia, altered mental status, and an elevated lactic acid level. In septic shock, systemic inflammation leads to profound peripheral vasodilation and a distributive shock state. The initial management bundle requires aggressive fluid resuscitation with intravenous crystalloids (typically

30 \text{ mL/kg}

within the first

3

hours) to restore intravascular volume and improve tissue perfusion. Additionally, immediate empiric broad-spectrum antibiotics must be administered. Given the timeline and hospital setting, hospital-acquired pneumonia (HAP) is the most likely infectious source. Empiric therapy must cover common nosocomial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. A combination of vancomycin and an antipseudomonal beta-lactam (such as cefepime) provides the necessary coverage.

Step-by-Step Solution

Analyze the clinical presentation and vital signs.

The patient has fever, hypotension, tachycardia, warm extremities, and right lower lobe consolidation on postoperative day 4.

This constellation indicates distributive (septic) shock secondary to hospital-acquired pneumonia (HAP).

Interpret the arterial blood gas using Winter's formula.

pH is

7.25

\text{HCO}_3^-

12 \text{ mEq/L}

, and

\text{PaCO}_2

28 \text{ mm Hg}

. Expected

\text{PaCO}_2 = 1.5(12) + 8 = 26 \pm 2

This reveals a primary metabolic acidosis (likely lactic acidosis) with appropriate and maximal respiratory compensation.

Determine the required evidence-based interventions.

The patient requires the sepsis resuscitation bundle, prioritizing intravascular volume expansion and early appropriate antimicrobial therapy.

Immediate

30 \text{ mL/kg}

crystalloid bolus treats the macrovascular perfusion deficit, while broad-spectrum antibiotics (covering Pseudomonas and MRSA) treat the underlying HAP.

Key Concept

The initial management of septic shock requires immediate crystalloid fluid resuscitation and empiric broad-spectrum intravenous antibiotics targeting the suspected source.

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic