Sandbox/00007

Cardiogenic Shock Resident Survival Guide
Overview
Causes
FIRE
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ahmed Zaghw, MBChB. [2]

Overview

The clinical definition of cardiogenic shock includes decreased cardiac output with evidence of tissue hypoxia in the presence of adequate intravascular volume.

Causes

Life Threatening Causes

Cardiogenic shock is a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

• Arrhythmic

• Atrioventricular block
• Sinoatrial block
• Supraventricular tachycardia
• Ventricular tachycardia

• Mechanical

• Acute mitral regurgitation (papillary muscle rupture, chordae tendinae rupture)
• Free wall rupture
• Hypertrophic cardiomyopathy
• Obstruction to left ventricular filling (mitral stenosis, left atrial myxoma)
• Obstruction to left ventricular outflow tract (aortic stenosis, hypertrophic obstructive cardiomyopathy)
• Ventricular septal defect

• Myopathic

• Cardiomyopathy
• Myocardial contusion
• Myocardial infarction
• Myocarditis
• Myxedema coma
• Postischemic myocardial stunning
• Septic myocardial depression

• Pharmacologic

• Anthracyclines
• Calcium channel blockers

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

A Focused Initial Rapid Evaluation (FIRE) should be performed to identify patients in need of immediate intervention.

Boxes in the salmon color signify that an urgent management is needed.

Abbreviations: CBC, complete blood count; CI, cardiac index; CK-MB, creatine kinase MB isoform; CVP, central venous pressure; DC, differential count; ICU, intensive care unit; INR, international normalized ratio; LFT, liver function test; MAP, mean arterial pressure; MVO2, mixed venous oxygen saturation; PCWP, pulmonary capillary wedge pressure; PT, prothrombin time; PTT, partial prothrombin time; SaO2, arterial oxygen saturation; SBP, systolic blood pressure; SCVO2, central venous oxygen saturation; SMA-7, sequential multiple analysis-7.

Does the patient have cardinal findings that increase the pretest probability of cardiogenic shock? ❑  Evidence of hypoperfusion ❑  Altered mental status ❑  Cool extremities ❑  Cyanosis ❑  Oliguria ❑  Sustained hypotension ❑  SBP <90 mm Hg for ≥30 min or ❑  MAP ↓ >30 mm Hg below baseline for ≥30 min ❑  Presence of myocardial dysfunction after exclusion or correction of non-myocardial factors contributing to tissue hypoperfusion

YES

NO

Cardiogenic shock suspected

Proceed to shock resident survival guide to identify and correct the cause

Immediate management (click for details) ❑  Intubation with mechanical ventilation ❑  ± Normal saline IV bolus 100–200 mL ❑  ± Norepinephrine IV infusion 0.1–2.0 μg/kg/min ❑  ± Morphine 2–4 mg IV push slowly (in 1–5 min) ❑  Hold antihypertensive medications ❑  Cardiology consultation

Workup ❑  ECG monitor ❑  Pulse oximeter ❑  Arterial blood gas ❑  Central venous catheter ❑  Pulmonary artery catheter ❑  CBC/DC/SMA-7/LFT/PT/PTT/INR ❑  Troponin, CK-MB ❑  Lactate ❑  Chest radiograph ❑  Echocardiography ❑  Foley catheter ❑  ICU admission

Immediate goals ❑  SaO2 >90%–92% ❑  CVP 8–12 mm Hg ❑  MAP >60 mm Hg ❑  PCWP 14–18 mm Hg ❑  CI >2.2 L/min/m2 ❑  MVO2 >60% ❑  SCVO2 >70% ❑  Hemoglobin >7–9 g/dL ❑  Lactate <2.2 mM/L ❑  Urine output >0.5 mL/kg/h ❑  ± Correct arrhythmia ❑  ± Correct electrolyte disturbance

Proceed to complete diagnostic approach below

Complete Diagnostic Approach

Treatment

Do's

Diagnostic criteria

• Criteria for bedside diagnosis

• Sustained hypotension (SBP <90 mm Hg or MAP 30 mm Hg below baseline in preexisting hypertension for at least 30 minutes)
• Evidence of tissue hypoperfusion (such as oliguria, cyanosis, cool extremities, and altered mental status)
• Presence of myocardial dysfunction after exclusion or correction of non-myocardial factors contributing to tissue hypoperfusion (such as hypovolemia, hypoxia, and acidosis)

• Criteria based on hemodynamic parameters

• Sustained hypotension (SBP <90 mm Hg or MAP 30 mm Hg below baseline in preexisting hypertension for at least 30 minutes)
• Depressed cardiac index (<1.8 L/min/m² of BSA without support or <2.0–2.2 L/min/m² of BSA with support) in the presence of an elevated wedge pressure (>15 mm Hg).

Immediate management

• Ventilatory support is crucial for maintenance of adequate oxygenation and usually requires intubation with mechanical ventilation.

• IV bolus normal saline should be waived in the presence of pulmonary edema.

• Norepinephrine

• Dosage and Administration

• Mix 1 ampule (4 mg) in 250 mL of D5W or D5NS.
• IV infusion 0.5–1.0 μg/min titrated to improve blood pressure (up to 30 μg/min).
• Avoid dilution in normal saline alone.
• Do not administer in same IV line as alkaline solutions.

• Indications

• For severe cardiogenic shock and hemodynamically significant hypotension (SBP <70 mm Hg) with a low systemic vascular resistance.
• This is an agent of last resort for management of ischemic heart disease and shock.

Don'ts

• Do not test orthostatic hypotension in hypotensive patients.
• Do not rely solely on SpO2 readings from pulse oximeter. SaO2 from blood gas analysis provides more precise status of oxygenation.
• Do not administer low-dose dopamine (<5 μg/kg/min) to preserve renal function in patients with shock.

References