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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 red 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 end-organ hypoperfusion ❑  Altered mental status ❑  Cold extremities ❑  Cyanosis ❑  Oliguria (urine output <0.5 mL/kg/h) ❑  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 ❑  ± Norepinephrine IV infusion 0.1–2.0 μg/kg/min

Immediate Workup ❑  ECG monitor ❑  Pulse oximeter ❑  Arterial blood gas ❑  Central venous catheter ❑  Pulmonary artery catheter ❑  CBC/DC/SMA-7/LFT/PT/PTT/INR ❑  Cardiac troponins, CK-MB ❑  BNP, NT-proBNP ❑  Lactate ❑  Chest radiograph ❑  Echocardiography ❑  Foley catheter ❑  ICU admission ❑  Cardiology consultation ❑  Hold antihypertensive medications

Cardiogenic shock confirmed (click for details on criteria)

Hemodynamic Optimization (click for details)

Preload ❑  Goal: PCWP 15–18 mm Hg ± correct pulmonary congestion ❑  ↑ PCWP by normal saline 100–200 mL IV bolus ❑  ↓ PCWP by furosemide 40 mg slow IV injection ❑  ± Morphine 2–4 mg slow IV injection

Afterload ❑  Goal: MAP >60 mm Hg, SVR 800–1200 dyn·s·cm−5 ❑  If ↑ MAP & ↑ SVR: wean vasopressors ± vasodilators ❑  If ↓ MAP & ↑ SVR: vasopressors + inotropes ❑  If ↓ MAP & ↓ SVR: vasopressors ± vasopressin

Cardiac Index ❑  Goal: CI >2.2 L/min/m2 ❑  ± Dobutamine ❑  ± Milrinone ❑  ± IABP, VAD, or ECMO if refractory

Immediate goals for oxygenation and perfusion ❑  SaO2 >90%–92% ❑  CVP 8–12 mm Hg ❑  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

Acute myocardial infarction likely? (click for details) ❑  Positive cardiac biomarkers (cTnT, cTnI, or CK-MB) ❑  Symptoms of myocaridal ischemia ❑  New significant ECG findings of myocardial ischemia

YES, then manage as UA/NSTEMI and proceed to acute ischemia pathway

No, then proceed to complete diagnostic approach

Acute Ischemia Pathway

Complete Diagnostic Approach

Treatment

Do's

Immediate management [Return to FIRE]

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

• Norepinephrine

• Dosage and Administration

• Mix 1 ampule (4 mg) of norepinephrine in 250 mL of D5W or D5NS. Avoid dilution in normal saline alone.
• IV infusion 0.5–1.0 μg/min; titrated to raise blood pressure (up to 30–40 μg/min).

• Contraindications

• Norepinephrine should not be given to patients who are hypotensive from blood volume deficits except as an emergency measure to maintain coronary and cerebral artery perfusion until blood volume replacement therapy can be completed.
• Norepinephrine should also not be given to patients with mesenteric or peripheral vascular thrombosis unless it is necessary as a life-saving procedure.

Criteria for Cardiogenic Shock [Return to FIRE]

• Clinical Criteria

• 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)

• Hemodynamic Criteria

• 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).

Hemodynamic Optimization [Return to FIRE]

• Preload: the goal is to maintain a PCWP of 15–18 mm Hg and to correct pulmonary congestion

• Pulmonary congestion

• Radiologic manifestations of pulmonary congestion reflect the extent of elevation in wedge pressure:

PCWP (mm Hg)	Phase of Pulmonary Congestion	Findings on Chest Radiograph
18–20	Onset of pulmonary congestion	Redistribution of pulmonary flow to the upper lobes ("cephalization") and Kerley lines
20–25	Moderate congestion	Diminished clarity of the borders of medium-sized pulmonary vessels ("perihilar haze")
25–30	Severe congestion	Radiolucent grapelike clusters surrounded by radiodense fluid ("periacinar rosette")
>30	Onset of pulmonary edema	Coalescence of periacinar rosettes resulting in "Bat's wing" opacities

• Furosemide

• Dosage and Administration

• For acute pulmonary edema, the initial dose is 40 mg injected slowly intravenously (over 1 to 2 minutes).
• If a satisfactory response does not occur within 1 hour, the dose may be increased to 80 mg injected slowly intravenously (over 1 to 2 minutes).

• Contraindications

• Anuria
• Hypersensitivity to furosemide

• Morphine

• Dosage and Administration

• Slow IV injection 2–4 mg (over 1–5 minutes) every 5–30 minutes as needed.

• Contraindications

• Hypersensitivity to morphine sulfate is one of the contraindications to its use.
• Morphine should not be used in convulsive states, such as those occurring in status epilepticus, tetanus, and strychnine poisoning.

• Morphine is also contraindicated in the following conditions: respiratory insufficiency or depression; bronchial asthma; heart failure secondary to chronic lung disease; cardiac arrhythmias; increased intracranial or cerebrospinal pressure; head injuries; brain tumor; acute alcoholism; and delirium tremens.

Criteria for Acute Myocardial Infarction [Return to FIRE]

• Detection of a rise and/or fall of cardiac biomarker values (preferably cardiac troponin) with at least one value above the 99th percentile upper reference limit and with at least one of the following:

• Symptoms of ischemia
• New or presumably new significant ST-segment–T wave (ST–T) changes or new left bundle branch block (LBBB).
• Development of pathological Q waves in the ECG.
• Imaging evidence of new loss of viable myocardium or new region wall motion abnormality.
• Identification of an intracoronary thrombus by angiography or autopsy.

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