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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 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 ❑  Cold 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 ❑  ± 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 ❑  Troponin, CK-MB ❑  Lactate ❑  Chest radiograph ❑  Echocardiography ❑  Foley catheter ❑  ICU admission ❑  Cardiology consultation ❑  Hold antihypertensive medications

Cardiogenic shock confirmed (click for details)

Hemodynamic optimization: preload ❑  Goal: PCWP 14–18 mm Hg ❑  ↑ PCWP by normal saline IV bolus 100–200 mL ❑  ↓ PCWP by furosemide slow IV injection (over 1–2 min) ❑  ± Correct pulmonary congestion (click for details) ❑  ± Morphine 2–4 mg slow IV injection (over 1–5 min)

Hemodynamic optimization: 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

Hemodynamic optimization: cardiac index ❑  Goal: CI >2.2 L/min/m2 ❑  ± Dobutamine ❑  ± Milrinone ❑  ± IABP, VAD, or ECMO if refractory

Immediate goals ❑  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

ACS 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/STEMI 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.

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

• 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).

• Indications

• Blood pressure control in certain acute hypotensive states (e.g., pheochromocytomectomy, sympathectomy, poliomyelitis, spinal anesthesia, myocardial infarction, septicemia, blood transfusion, and drug reactions).
• Adjunct in the treatment of cardiac arrest and profound hypotension.

• Precautions

• Do not administer in same IV line as alkaline solutions.

• Morphine

• Dosage and Administration

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

• Indications

• Relief of severe pain as in severe injuries or in severe chronic pain associated with terminal cancer after all non-narcotic analgesics have failed.
• Relief of chest discomfort that is unresponsive to nitrates in STEMI (Class I, LOE C) and unstable angina or NSTEMI (Class IIa, LOE C).
• Management of dyspnea associated with acute left ventricular failure and pulmonary edema to relieve anxiety and reduce preload.
• Preoperative sedation to facilitate anesthesia induction and reduce anesthetic dosage.

• Precautions

• May cause respiratory depression
• May exacerbate hypotension in volume-depleted patients.

Criteria for Cardiogenic Shock  Return to FIRE

• 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).

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