Cardiogenic Shock and Obstructive Shock

Definition/Etiology:

Reduced cardiac output (CO=SVxHR) can cause a drop in tissue perfusion, and cellular hypoxia. This results in dysregulation of pH, multiorgan failure, and death if not reversed.

Cardiogenic (pump failure)

• Cardiomyopathy: heart muscle dysfunction, reduced squeeze, systolic failure, decreased SV
• Arrhythmia: tachy can cause decreased SV (reduced filling time); brady results in decreased HR; BBB causes ventricular dyssynchrony and paradoxical septal motion, decreasing SV; atrial arrhythmias lose atrial kick and decrease SV
• Mechanical: valvular disease, acute septal rupture or papillary muscle rupture s/p MI

Obstructive (reduced preload)

• Pulmonary vascular: right heart strain from PE or pulmonary hypertension. Hypoxia of shock worsens pulmonary vascular resistance.
• Mechanical: tension pneumothorax, pericardial tamponade, constrictive pericarditis, restrictive cardiomyopathy

Pathophysiology:

An inadequate tissue perfusion which impairs the ability normal cellular metabolism. Cardiogenic shock specifically is when the heart (or pump) fails to pump out enough blood to meet the oxygen demands on the body.

• Valvular heart disease, and acute papillary rupture, and PE put strain on the heart and reduce SV.
• Pericardial tamponade and tension pneumothorax
• Decreased SV with diastolic HF.

Clinical Presentation:

• “Cool and Wet”
• Hypotension
• Diaphoresis
• Dyspnea
• Tripoding
• Orthopnea (pulmonary congestion)
• Pulmonary edema on CXR
• Cool extremities (poor perfusion)
• Crackles on lung auscultation
• Poor appetite, early satiety
• Pink frothy sputum
• Leg edema
• Abdominal edema
• Oliguria
• Metabolic acidosis
• Chest pain?

Collaborative Management:

• Labs: BNP, Troponin, CMP
• CXR
• Echocardiogram: assess ejection fraction, valves, pericardial sac
• 12 lead EKG
• Continuous rhythm monitoring
• Freq NIBP vs Invasive hemodynamic monitoring
• Diuretics (Furosemide)
• Positive inotropes (Digoxin)
• Vasopressors (Norepinephrine)
• Positive chronotropes if brady (Dopamine)
• Cath lab: left and/or right cardiac cath, mechanical support (Impella vs IABP)

Evaluation | Patient Monitoring | Education:

• Continuous rhythm monitoring
• Freq NIBP vs Invasive hemodynamic monitoring
• Continuous oxygen saturation monitoring
• Oxygen as needed, possibly intubation vs Bipap
• Monitor urine output
• Delay patient education until more stable, provide emotional support to patient and family

Linchpins: (Key Points)

• Pump problems can originate inside or outside the heart.
• CO = HR x SV
• The heart must be able to squeeze well and relax well in order to maintain good cardiac output.
• Rhythm problems (fast/slow, BBB, AF/AFL) can all have an effect on cardiac output.