# A 68-year-old patient with a history of coronary artery disease presents with cardiogenic shock following acute myocardial infarction. The patient's blood pressure is 78/45 mmHg, heart rate is 118 bpm, and urine output has decreased to 10 mL/hr over the past 2 hours. Which nursing intervention should be the priority?

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## 문제

A 68-year-old patient with a history of coronary artery disease presents with cardiogenic shock following acute myocardial infarction. The patient's blood pressure is 78/45 mmHg, heart rate is 118 bpm, and urine output has decreased to 10 mL/hr over the past 2 hours. Which nursing intervention should be the priority?

## 보기

1. Administer IV fluid bolus of 500 mL normal saline rapidly
2. Prepare for intra-aortic balloon pump **✔ 정답**
3. Increase oxygen delivery to 100% via non-rebreather mask
4. Administer furosemide 40 mg IV push to improve urine output

**정답: 2**

## 해설

In cardiogenic shock, the heart's pumping ability is severely compromised, leading to inadequate tissue perfusion. The IABP is a mechanical circulatory support device that improves coronary perfusion and reduces cardiac workload.

Cardiogenic shock is a life-threatening condition where more than 40% of the left ventricular myocardium is damaged after an acute myocardial infarction, severely impairing the heart's pumping function so it cannot pump enough blood to meet the body's metabolic demands. Pathophysiologically, reduced cardiac output causes hypotension, which further decreases coronary artery perfusion, leading to additional myocardial damage and worsening heart function in a vicious cycle.

The intra-aortic balloon pump (IABP) is the standard mechanical circulatory support device for cardiogenic shock. This device operates on the principle of counterpulsation, where the balloon inflates during diastole to increase diastolic pressure and improve coronary artery perfusion, and deflates during systole to reduce afterload and decrease cardiac workload. This dual mechanism helps break the vicious cycle of deteriorating heart function by improving myocardial oxygen supply while reducing oxygen demand.

In this scenario, the patient shows classic signs of cardiogenic shock: hypotension (78/45 mmHg), tachycardia (118 bpm), and oliguria (15 mL/hr) indicating inadequate organ perfusion. The priority is to provide immediate mechanical support to improve cardiac output and tissue perfusion. IABP insertion is the most appropriate intervention that addresses the underlying pathophysiology by directly supporting the failing heart function.

Early recognition and prompt intervention with mechanical circulatory support can significantly improve outcomes in cardiogenic shock, where mortality exceeds 50% without appropriate treatment. The nurse's role includes rapid assessment, preparation for IABP insertion, and continuous monitoring of hemodynamic parameters.

## 심화 해설

Understanding Cardiogenic Shock

This patient is in cardiogenic shock (CS) following an acute myocardial infarction (AMI). The defining feature of CS is primary cardiac pump failure, leading to profound tissue hypoperfusion. The clinical picture here is classic: a critically low blood pressure of 78/45 mmHg, a compensatory tachycardia of 118 bpm, and severe oliguria of 10 mL/hr, which signals that the kidneys are not being adequately perfused. Management is guided by the patient's hemodynamic profile and the stage of shock, with mechanical circulatory support (MCS) becoming a cornerstone in advanced stages [3].

Analysis of the Priority Intervention

The correct answer is to prepare for an intra-aortic balloon pump (IABP). In the context of AMI-related CS, the primary problem is not a lack of fluid volume but a failure of the left ventricle to effectively pump blood forward. An IABP is a mechanical circulatory support device that provides two critical benefits: it inflates during diastole, augmenting coronary artery perfusion pressure and thus oxygen delivery to the struggling myocardium, and it deflates just before systole, which reduces the afterload the left ventricle must pump against. This simultaneous improvement in myocardial oxygen supply and reduction in cardiac workload directly addresses the underlying pathophysiology. Modern guidelines and algorithms for CS management recommend the use of MCS devices, including IABP, based on the patient's hemodynamic profile and SCAI shock stage, particularly when there is evidence of end-organ hypoperfusion as seen here [3]. Furthermore, in severe cases, an IABP can be a crucial adjunctive therapy, even when more advanced support like veno-arterial ECMO is being considered, to mitigate left ventricular overload and promote myocardial recovery [2,4].

Why Other Interventions Are Not the Priority

- Administer IV fluid bolus of 500 mL normal saline rapidly: This is incorrect and potentially harmful. While fluid resuscitation is key in distributive shock (e.g., sepsis), in cardiogenic shock, the failing left ventricle is already volume-overloaded and unable to handle additional preload. A rapid fluid bolus can precipitate acute pulmonary edema and worsen respiratory function without improving cardiac output .

- Increase oxygen delivery to 100% via non-rebreather mask: While ensuring adequate oxygenation is an important supportive measure, it does not address the root cause of the shock, which is the heart's mechanical pumping failure. This is a supportive, not a definitive, intervention. The priority is to improve cardiac output and systemic perfusion, which an IABP can directly assist with.

- Administer furosemide 40 mg IV push to improve urine output: This is contraindicated in the acute phase. The oliguria is not due to fluid overload but to renal hypoperfusion from a low cardiac output state. Administering a diuretic would cause further volume depletion, potentially dropping the blood pressure even lower and worsening renal function. The focus must be on restoring forward flow, not forcing urine output from underfilled renal arteries. The cornerstone of therapy for restoring perfusion involves inotropic/vasopressor support and mechanical circulatory support, not diuresis [3].

References (research sources)

- [3]A Proposed Algorithm for the Management of Patients with Cardiogenic Shock Based on Contemporary Knowledge and Gaps in Evidence.Research articleRammos A, Floros CD, Tzourtzos I, Stamou IE, Kalogeras P, Samara I, Siaravas KC, Bouratzis V, Bechlioulis A, Sakellariou XM, Naka KK, Michalis LK. (2025) · DOI: 10.3390/jcdd12120489

## 임상 시나리오

Clinical Management Guide: Cardiogenic Shock Post-MI

**Core Principle:** Cardiogenic shock is a pump problem, not a volume problem. The priority is to restore cardiac output and tissue perfusion without overloading the failing ventricle.

Step 1: Immediate Recognition & Hemodynamic Assessment

- **Key Indicators:** Systolic BP < 90 mmHg, cardiac index < 2.2 L/min/m², pulmonary capillary wedge pressure > 15 mmHg, signs of end-organ hypoperfusion (oliguria, altered mental status, cool extremities).

- **Bedside Clues:** Narrow pulse pressure, tachycardia, rising lactate, and declining urine output are early warning signs.

Step 2: Prioritize Mechanical Circulatory Support (MCS)

- **Intra-Aortic Balloon Pump (IABP):** First-line temporary MCS. It reduces afterload and augments diastolic coronary perfusion. Prepare the patient by explaining the procedure, ensuring vascular access, and monitoring for limb ischemia or bleeding.

- **Advanced Options:** Impella, TandemHeart, or VA-ECMO may be considered based on institutional protocols and severity.

Step 3: Cautious Pharmacologic Support

- **Inotropes:** Dobutamine or milrinone to improve contractility. Use with caution as they increase myocardial oxygen demand.

- **Vasopressors:** Norepinephrine is preferred to maintain a mean arterial pressure (MAP) of at least 65 mmHg if hypotension persists after MCS.

- **Avoid:** Large-volume fluid boluses (risk of pulmonary edema) and diuretics (will worsen preload and hypotension).

Step 4: Definitive Revascularization

- **Urgent PCI or CABG:** The underlying cause is often acute coronary occlusion. Early revascularization is the only intervention proven to reduce mortality.

- **Nursing Role:** Prepare the patient for the catheterization lab, maintain NPO status, administer antiplatelet and anticoagulant therapy as ordered, and monitor for arrhythmias.

Ongoing Nursing Monitoring

- **Hemodynamics:** Continuous arterial pressure monitoring, central venous pressure, and hourly urine output.

- **Perfusion:** Assess skin color, temperature, capillary refill, and mentation every 15-30 minutes.

- **Device-Specific:** For IABP, check timing, balloon migration, and pedal pulses distal to the insertion site hourly.

## 핵심 개념

- **Cardiogenic Shock** — A state of end-organ hypoperfusion due to primary cardiac pump failure, often following acute myocardial infarction.
- **Intra-Aortic Balloon Pump** — A mechanical circulatory support device that inflates in diastole to augment coronary perfusion and deflates before systole to reduce afterload.
- **Afterload** — The pressure the left ventricle must overcome to eject blood; reducing it decreases myocardial oxygen demand.
- **Oliguria** — Urine output less than 30 mL/hr, indicating decreased renal perfusion and a critical sign of shock.
- **Hemodynamic Profile** — A set of measurements including blood pressure, heart rate, and cardiac output used to guide shock management.

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