A nurse is caring for a patient with cardiogenic shock who has a pulmonary artery catheter in place. Which assessment finding would be the MOST concerning and require immediate intervention?

Mixed venous oxygen saturation (SvO2) of 45% indicates severe tissue hypoxia and inadequate oxygen delivery, requiring immediate intervention to prevent organ failure. Other parameters are abnormal but expected in cardiogenic shock and represent less immediate risk.

Core Nursing Explanation Key Concept Analysis: This question tests the critical assessment of hemodynamic monitoring data in a patient with Cardiogenic shock. It requires you to prioritize which abnormal finding indicates the most severe, life-threatening condition requiring immediate action. Cardiogenic shock is characterized by the heart's inability to pump sufficient blood to meet the body's metabolic demands, leading to hypoperfusion and tissue hypoxia. While all parameters are important, the nurse must identify the finding that signals the most profound failure of oxygen delivery to the tissues.

Answer Rationale: Key Point! Mixed venous oxygen saturation (SvO₂) is a direct measure of the balance between oxygen delivery (DO₂) and oxygen consumption (VO₂) at the tissue level. A normal SvO₂ is 60-80%. A value of 45% indicates that tissues are extracting an extremely high amount of oxygen from the blood because delivery is critically low. This is a late sign of global tissue hypoxia and impending multi-organ failure. In cardiogenic shock, a low cardiac output is the primary problem, and a severely low SvO₂ confirms that the shock state is profound and not being compensated for, demanding immediate intervention (e.g., inotropic support, mechanical circulatory support) to improve cardiac output and oxygen delivery.

Distractor Analysis:
Watch out for confusion! Option ①: Pulmonary artery wedge pressure (PAWP) of 22 mm Hg is elevated (normal: 4-12 mm Hg). This indicates left ventricular failure and pulmonary congestion, which is a hallmark of cardiogenic shock. While concerning and requiring management (e.g., diuretics), it is an expected finding in this condition and does not, by itself, indicate the same level of immediate, life-threatening tissue hypoxia as a critically low SvO₂.
Option ③: Cardiac index (CI) of 1.8 L/min/m² is low (normal: 2.5-4.0 L/min/m²). This confirms the diagnosis of cardiogenic shock (CI typically

Nursing Clinical Practice Guide Clinical Scenario: You are the nurse in the Cardiac Intensive Care Unit (CICU) caring for Mr. Johnson, a 68-year-old man admitted with an extensive anterior MI now in cardiogenic shock. He is intubated, sedated, on a dobutamine drip, and has a pulmonary artery catheter in place. During your hourly hemodynamic checks, you record the following: PAWP 20 mm Hg, CI 1.9 L/min/m², CVP 12 mm Hg, and SvO₂ 45%.

Nursing Intervention Strategy:

1. Immediate Assessment & Action: Validate the SvO₂ reading. Check the PA waveform to ensure the catheter is not wedged. Check arterial blood gas (ABG) and serum lactate levels to corroborate tissue hypoxia. Immediately notify the cardiologist or intensivist of the critically low SvO₂. This is a "must-report" value.
2. Collaborative Interventions: Prepare for potential adjustments per provider order:
   • Increase Inotropic Support: The dobutamine drip may be titrated upward to improve contractility and cardiac output.
   • Optimize Preload & Afterload: Based on PAWP and blood pressure, the team may consider a careful fluid challenge or adding a vasodilator like nitroprusside.
   • Consider Mechanical Support: Discuss the potential need for an intra-aortic balloon pump (IABP) or other ventricular assist device.
3. Ongoing Monitoring: After interventions, monitor SvO₂ trends every 15-30 minutes. Continuously assess end-organ perfusion: urine output (