Shock resident survival guide

Shock Resident Survival Guide
Overview
Causes
FIRE
Management
Diagnostic Approach
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Synonyms and keywords: Circulatory shock

Overview

Shock is the syndrome of circulatory failure that results in inadequate cellular oxygen utilization. The diagnosis of shock is based on clinical signs and biochemical abnormalities indicative of tissue hypoperfusion.

Causes

Life Threatening Causes

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

Common Causes

• Cardiogenic shock

• Arrhythmic

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

• Mechanical

• Hypertrophic cardiomyopathy
• Acute mitral regurgitation
• Ventricular septal defect

• Myopathic

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

• Pharmacologic

• Anthracycline
• Calcium channel blockers

• Obstructive shock

• Decreased cardiac compliance

• Cardiac tamponade
• Constrictive pericarditis

• Decreased ventricular preload

• Intrathoracic tumor
• Mechanical ventilation with positive end-expiratory pressure (PEEP)
• Tension pneumothorax

• Increased ventricular afterload

• Aortic dissection
• Pulmonary embolism
• Acute pulmonary hypertension

• Hypovolemic shock

• Fluid depletion

• Dehydration
• Diarrhea
• Extensive burns
• Polyuria
• Vomiting
• Third spacing (as in endometritis, pancreatitis, peritonitis, pleural effusions)

• Hemorrhage

• Ectopic pregnancy
• Gastrointestinal bleeding
• Perforated peptic ulcer
• Post-procedural or post-surgical
• Retroperitoneal hemorrhage
• Rupture ovarian cyst
• Trauma

• Distributive shock

• Sepsis
• Toxic shock syndrome
• Anaphylactic or anaphylactoid reaction
• Neurogenic shock
• Adrenal crisis
• Thyroid storm

Click here for the complete list of causes.

FIRE: Focused Initial Rapid Evaluation

Perform Focused Initial Rapid Evaluation (FIRE) to identify patients requiring immediate intervention.

Abbreviations: ECG: electrocardiogram

• History

• Symptoms

• Physical examination

• Laboratory findings

• ECG findings

Management

Shock

Initial Management Ventilate—Infuse—Pump (VIP) ❑ Intubation with mechanical ventilation ❑ Normal saline 0.5–1.0 L q10–15 min ❑ ± Transfusion as needed ❑ ± Norepinephrine 0.1–2.0 μg/kg/min ❑ Arterial blood gas ❑ Pulse oximetry ❑ ECG monitor ❑ Central venous catheter ❑ ICU admission

Workups ❑ CBC/DC/SMA-7/LFT/PT/PTT/INR ❑ Troponin ± CK-MB ❑ Lactate ❑ CXR ❑ ± Cultures of blood, urine, sputum, etc. ❑ ± Echocardiography ❑ ± Pulmonary artery catheter

Immediate Goals ❑ SaO2 >90%–92% ❑ CVP 8–12 mmHg ❑ MAP >65–70 mmHg ❑ PCWP 12–15 mmHg ❑ CI >2.1 L/min/m2 ❑ MVO2 >60% ❑ SCVO2 >70% ❑ Hemoglobin >7–9 g/dL ❑ Lactate <2.2 mM/L ❑ Urine output >0.5 mL/kg/h

Classify Shock and Treat Accordingly

Cardiogenic Shock

Obstructive Shock

Distributive Shock

Hypovolemic Shock

Complete Diagnostic Approach

History

• Review all medications

• Antihypertensives can cause significant hypotension, especially in the setting of volume depletion or over-diuresis.
• Anaphylaxis should be considered if the patient recently started on a new drug and presented with respiratory distress.

• Accompanying symptoms that could pinpoint the underlying disease include:

• Abdominal pain
• Chest discomfort
• Diarrhea
• Dyspnea
• Hematemesis
• Hematochezia
• Polydipsia
• Polyuria
• Vomiting

Physical Examination

• Vital signs

• Temperature

• Fever may suggest sepsis or anaphylactic reaction related to transfusion.
• Hypothermia may be associated with sepsis, adrenal crisis, or myxedema.

• Pulse

• Bradycardia or tachycardia can either be a primary or secondary process.
• Pulsus paradoxus may be seen in cardiac tamponade, pulmonary embolism, hemorrhagic shock, or tension pneumothorax.
• Pulsus alternans may be seen in heart failure, severe aortic insufficiency, or hypovolemic shock.

• Respiration

• Tachypnea commonly occurs in pneumothorax, sepsis, and cardiogenic shock.
• Hypopnea may be seen in narcotic overdose.

• Blood pressure

• Confirm arterial hypotension by checking blood pressure in both arms manually. Arterial line may be considered.
• Postural hypotension suggests volume depletion or autonomic dysfunction. Do not test orthostatic hypotension in hypotensive patients.

• Mental status

• Altered mental status may indicate inadequate perfusion to vital organs or use of sedatives or narcotics.

• Cutaneous

• Decreased skin turgor signifies dehydration.
• Cool extremities, clammy and mottled skin, peripheral cyanosis, and delayed capillary refill are commonly noted in cardiogenic shock and hypovolemic shock, whereas warm and moist skin may represent hyperdynamic phase of septic shock.
• Extensive burns and severe trauma may be evident on inspection and are associated with significant fluid loss.
• Hyperpigmentation may be an indicator of adrenal crisis.

• Neck

• Elevated jugular venous pressure correlates with increased left ventricular end diastolic pressure and decreased left ventricular ejection fraction and suggests heart failure, tricuspid stenosis, pulmonary hypertension, superior vena cava obstruction, constrictive pericarditis, or cardiac tamponade.
• Kussmaul's sign may occur with constrictive pericarditis, restrictive cardiomyopathy, tricuspid stenosis, superior vena cava obstruction, or right ventricular infarction.
• Abdominojugular reflux

• A positive abdominojugular reflux correlates with a PCWP of 15 mmHg or greater and suggests constrictive pericarditis, cardiac tamponade, tricuspid insufficiency, inferior vena cava obstruction, or heart failure (except pure backward left-sided heart failure).

• Jugular venous pressure waveform

• Blunted y descent suggests cardiac tamponade or tricuspid stenosis.
• Steep y descent suggests constrictive pericarditis or severe tricuspid insufficiency.

• Cardiovascular

• Decrescendo early systolic murmur

• Acute severe mitral regurgitation

• Third heart sound (S₃)

• Heart failure

• Pansystolic murmur along lower left sternal border with palpable thril

• Ventricular septal defect

• Pericardial friction rubs

• Pericarditis

• Distant, muffled heart sounds

• Cardiac tamponade

• Pulmonary

• Tracheal deviation

• Tension pneumothorax

• Stridor and wheezing

• Anaphylaxis
• Acute exacerbation of chronic obstructive pulmonary disease

• Rales

• Anaphylaxis
• Pneumonia
• Heart failure

• Chest percussion may aid in the diagnosis of tension pneumothorax, pleural effusions, and pneumonia

• Abdominal

• Ecchymoses

• Retroperitoneal hemorrhage

• Hepatomegaly

• Inferior vena cava obstruction
• Heart failure

• Rebound tenderness with absent bowel sounds

• Sepsis due to Intraabdominal infection
• Gastrointestinal hemorrhage

• Pulsatile mass

• Abdominal aortic aneurysm

• Extremities

• Digital clubbing

• Heart failure

• Edema

• Heart failure

• Erythema at the site of vascular access

• Catheter-associated infection

• Pelvic girdle pain or instability

• Pelvic fracture

• Genitals

• Perform a pelvic examination in women of childbearing age to rule out ectopic pregnancy or pelvic infection.

Laboratory Findings

ECG Findings

• ST segment elevation or depression, pathologic Q waves, hyperacute or negative T waves

• Myocardial infarction or ischemia

• Sinus tachycardia with S1Q3T3 pattern

• Acute pulmonary embolism

• Low QRS voltage with electrical alternans

• Cardiac tamponade

• QS deflections in precordial leads with right axis deviation and low QRS voltage

• Pneumothorax

• Bradyarrhythmias or tachyarrhythmias

Hemodynamic Profiles and Echocardiography Findings

Classification of shock based on hemodynamic profiles and echocardiographic findings.

Type of Shock		CO	SVR	PCWP	CVP	SVO2	Echocardiographic Findings
Cardiogenic	Acute Ventricular Septal Defect	↓↓	↑	N — ↑	↑↑	↑ — ↑↑	Large ventricles with poor contractility
	Acute Mitral Regurgitation	↓↓	↑	↑↑	↑ — ↑↑	↓
	Myocardial Dysfunction	↓↓	↑	↑↑	↑↑	↓
	RV Infarction	↓↓	↑	N — ↓	↑↑	↓	Dilated RV, small LV, abnormal wall motions
Obstructive	Pulmonary Embolism	↓↓	↑	N — ↓	↑↑	↓	Dilated RV, small LV
	Cardiac Tamponade	↓ — ↓↓	↑	↑↑	↑↑	↓	Pericardial effusion, small ventricles, dilated inferior vena cava
Distributive	Septic Shock	N — ↑↑	↓ — ↓↓	N — ↓	N — ↓	↑ — ↑↑	Normal cardiac chambers with preserved contractility
	Anaphylactic Shock	N — ↑↑	↓ — ↓↓	N — ↓	N — ↓	↑ — ↑↑
Hypovolemic	Volume Depletion	↓↓	↑	↓↓	↓↓	↓	Small cardiac chambers with normal or high contractility

Do's

• Resuscitation should be initiated while investigation of the cause is ongoing. Correct the cause of shock immediately once it is identified.
• Administer empiric antibiotics if sepsis is a concern.

Don'ts

• Do not test orthostatic hypotension in hypotensive patients.

References

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