A client recovering from a massive anterior wall myocardial infarction is being monitored … — NCLEX-RN

A client recovering from a massive anterior wall myocardial infarction is being monitored with a pulmonary artery catheter. Over the last hour, the client has become increasingly lethargic. The nurse evaluates the following hemodynamic and laboratory parameters:

- Heart rate: $118$ beats/min
- Mean arterial pressure (MAP): $54$ mm Hg
- Central venous pressure (CVP): $16$ mm Hg (Normal: $2$ - $8$ mm Hg)
- Pulmonary artery wedge pressure (PAWP): $24$ mm Hg (Normal: $6$ - $12$ mm Hg)
- Cardiac index (CI): $1.7$ L/min/m $^2$ (Normal: $2.5$ - $4.0$ L/min/m $^2$ )
- Systemic vascular resistance (SVR): $2150 \text{ dynes/sec/cm}^{-5}$ (Normal: $800$ - $1200 \text{ dynes/sec/cm}^{-5}$ )

Arterial blood gas (ABG) results on a $40\%$ Venturi mask reveal: pH $7.24$ , PaCO $_2$ $58$ mm Hg, HCO $_3^-$ $25$ mEq/L, and PaO $_2$ $58$ mm Hg.

Based on this physiological presentation, which intervention most accurately addresses the primary pathophysiological failure?

Administering an inotropic agent combined with a loop diuretic to improve myocardial contractility and reduce cardiac filling pressures.Answer
B
Titrating a peripheral vasoconstrictor to elevate systemic vascular resistance and restore a viable mean arterial pressure.
C
Delivering a bolus of isotonic crystalloids to increase circulating volume and optimize the depressed cardiac index.
D
Infusing sodium bicarbonate to neutralize excess serum hydrogen ions and reverse the profound metabolic acidosis.

Answer

The correct intervention is administering an inotropic agent combined with a loop diuretic to improve myocardial contractility and reduce cardiac filling pressures.

The client is in severe cardiogenic shock, evidenced by a profoundly depressed cardiac index, elevated left-sided filling pressures (PAWP), and a compensatory severe elevation in systemic vascular resistance (SVR). The failure of the left ventricle to pump effectively has caused fluid to back up into the pulmonary vasculature, resulting in alveolar flooding (pulmonary edema). This fluid barrier impairs gas exchange, directly leading to severe hypoxemia and acute uncompensated respiratory acidosis. The priority physiological intervention is to concurrently enhance myocardial contractility using positive inotropes and reduce the volume overload (preload) with loop diuretics. This combined approach improves forward blood flow, reduces the pulmonary hydrostatic pressure, and ultimately relieves the respiratory failure.

Step-by-Step Solution

Analyze the hemodynamic profile to determine the specific shock state.

The depressed cardiac index (

1.7

), highly elevated filling pressures (CVP

16

, PAWP

24

), and compensatory severe vasoconstriction (SVR

2150

) confirm cardiogenic shock with severe left ventricular failure.

Accurately identifying the shock etiology dictates the necessary physiological interventions and rules out contraindications like fluid boluses.

Interpret the arterial blood gas (ABG) findings.

The low pH (

7.24

), elevated PaCO

_2

(

58

), and normal HCO

_3^-

(

25

) indicate acute, uncompensated respiratory acidosis.

Determining the exact acid-base imbalance prevents the administration of inappropriate metabolic treatments such as sodium bicarbonate.

Synthesize the data to identify the primary pathophysiological cascade.

Myocardial pump failure has caused blood to back up into the pulmonary vasculature (high PAWP), resulting in alveolar flooding (pulmonary edema), which in turn causes impaired gas exchange, hypoxemia, and carbon dioxide retention.

Understanding the cause-and-effect relationship between cardiac failure and respiratory compromise is essential for clinical prioritization.

Select the pharmacological intervention that targets the root physiological cause.

Inotropes increase forward blood flow (contractility), and loop diuretics reduce the fluid overload (preload), thereby resolving both the primary shock state and the secondary respiratory acidosis.

Treatments must address pump efficiency and fluid volume simultaneously without increasing the cardiac workload (afterload).

Key Concept

Hemodynamic profile analysis and ABG interpretation in cardiogenic shock complicated by acute respiratory failure.

Estimated Time:2m 30s

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