Cardiogenic Shock

                        

Cardiogenic Shock

Cardiogenic Shock is characterized by

            low cardiac output

            hypotension

                        causing inadequate tissue perfusion.

Cardiogenic shock may occur as a complication of

(1) following surgery

(2) septicemia

(3) severe burns

(4) immunologic disease (anaphylaxis)

(5) hemorrhage or dehydration

(6) acute central nervous system disorders.

Treatment

            reinstitution of adequate cardiac output and peripheral perfusion

            prevent the untoward effects of prolonged ischemia to vital organs

            management of the underlying cause.

Physiology - 

            cardiac output is increased as a result of sympathetic discharge à increases heart rate.

 in cardiogenic shock -- heart rate will not increase further and may reduce cardiac output by decreasing diastolic filling time.

Cardiac output must be increased by increasing stroke volume.

If the rate of fluid administration is increased, the central venous pressure and ventricular filling pressure (preload) increase

the Frank-Starling mechanism results in an increased stroke volume.

filling pressure depends on

            ventilatory support

            positive end-expiratory pressure

            peak inspiratory pressure

            intra-abdominal pressure.

If fluid administration does not result in improved cardiac output,

            abnormal Myocardial contractility or high afterload, or both, must be the cause of the low cardiac output.

Myocardial contractility

            improves when treatment of the basic cause of shock is instituted

            hypoxia is eliminated

            acidosis is corrected.

dopamine, epinephrine, and dobutamine

            improve cardiac contractility

            increase heart rate

            increase cardiac output.

Digoxin should be avoided.

            adverse effects may result from larger doses

            toxicity is less predictable, depending on myocardial and serum potassium and calcium levels.

patients with cardiovascular shock have compromised renal perfusion

digoxin may result in high blood levels because it is excreted in the kidneys

High after load

Patients may have a increase in systemic vascular resistance

            resulting in high afterload

            poor peripheral perfusion.

afterload-reducing agents =, nitroprusside used in combination with dopamine.

pulmonary thermo-dilution catheter = measures cardiac index and to calculate systemic vascular resistance

intra-aortic balloon counter-pulsation

                        reduces afterload by mechanical means

                        increases diastolic coronary perfusion.

ECMO - extracorporeal membrane oxygenation is useful in reversible ventricular failure

sugf � s @�� (y� ardiac disease.

Assess pulse (central and peripheral) and capillary refill (assuming extremity is warm): <2 sec is normal, 2 to 5 sec is delayed, and >5 sec is markedly delayed, suggesting shock. Decreased or altered mental status may be a sign of inadequate perfusion.

Blood pressure (BP): Measuring blood pressure is one of the least sensitive measures of adequate circulation in children.

MANAGEMENT

Chest compressions

Fluid resuscitation

If peripheral intravenous (IV) access is not obtained in 90 sec or three attempts, and the patient is <8 years old, then place an intraosseous (IO) needle

If still unsuccessful, consider central venous access.

Initial fluid should be lactated Ringer’s (LR) or normal saline (NS).

Administer a bolus with 20 mL/kg over 5 to 15 minutes. Reassess. If there is no improvement, consider a repeat bolus with 20 mL/kg of the same fluid.

Reassess. If replacement requires more than 40 mL/kg, or if there is acute blood loss, consider 5% albumin, plasma, or packed red blood cells (RBCs) at 10 mL/kg.

If cardiogenic etiology is suspected, fluid resuscitation may worsen clinical status.

Pharmacotherapy: See inside front and back covers for guidelines for drugs to be considered in cardiac arrest.

Note: Consider early administration of antibiotics or corticosteroids if clinically indicated.

MANAGEMENT OF CIRCULATION

 Location *                                           Rate (per min) Compressions:   Ventilation

Infants                                       >100                                                    5:1

1 finger-breadth below intermammary line

Children (<8 yr)                                    100                                                      5:1

2 finger-breadths below intermammary line    

Older children                           100                                                      15:2

(>8 yr Lower half of sternum  

*Depth of compressions should be one third to one half anteroposterior (AP) diameter of the chest and should produce palpable pulses.