SHOCK


DEFINITION

Basic derangement is inadequate cardiac output with compensatory vasoconstriction and tissue hypoperfusion.

TYPES

a] Hypovolemic shock
Hemorrhage, severe vomiting and diarrhea, burns, acute pancreatitis, diabetic ketoacidosis.
b] Cardiogenic shock
Acute MI( >40% of myocardium damaged), acute AR(aortic regurgitation), MR(mitral regurgitation), myocarditis, dilated cardiomyopathy.
c] Septic shock
Gram +ve and -ve bacteria.
d] Anaphylactic shock
Drugs.
e] Neurogenic shock
High cervical cord injury, severe head injury.

PATHOPHYSIOLOGY

a] Sympathoadrenal and neuroendocrine response
Hypotension stimulates baroreceptor and chemoreceptors leads to increased sympathetic activity.
Hypoperfusion of kidney release renin in turn angiotensin.
During shock increased ADH and cortisol release retaining fluid and sodium.

b] Inflammatory reaction
More apparent in septic shock.
Endotoxin by Gram-ve bacteria stimulate release of cytokine(TNF-tumor necrosis factor, IL-1, IL-10), PAF(platelet activation factor), PG(prostaglandins) and LT(leukotrienes), activation of complement components.

CLINICAL FEATURES

  • Systolic BP <100 mmHg Tachycardia (>100/min)
  • Cold clammy skin
  • Tachypnea, Cheyne-Stoke breathing
  • Urine output <30 ml/hr

MANAGEMENT

A] Patient monitoring

Monitor pulse BP, RR and ECG for heart rhythm.
ABG(atrial blood gas) and pH analysis for correction of acidosis and hypoxia.
Central venous pressure monitor.
Pulmonary capillary wedge pressure with Swan Ganz catheter.
Urinary and arterial catheterization.

B] General Measures

Care of airway bowel, bladder and nutrition.
Relieve pain and anxiety.
Correction hypovolemia by blood, RL, isotonic NS , dextran, albumin, plasma.
Prevention and treatment of renal complications after correction of hypovolemia.
Diuresis by furosemide or mannitol.
IV Low dose dopamine vasodilator of renal vessels.
Correction of hypoxia by face mask oxygen or intubate.
Correction of acidosis by IV sodium bicarbonate.
Treatment of cardiac arrhythmia with drugs, electrical cardioversion.
Treatment of sepsis by Antibiotic.

C] Sympathomimetic Amines

Only used after correcting volume deficit.
Act by increasing CO selective vasoconstriction.
Raised BP and redistribute blood flow to vital organs but away from skin and skeletal muscle.
Aim is elevation of systolic BP between 110- 120 mmHg and maintain urinary output >30 ml/hr.
Drugs
Dopamine: 3 – 10 or >10 micro gm /kg/min.
Dobutamine: 1-10 micro gm/kg/min.
Noradrenaline: 2-8 micro gm/kg/min.
Adrenaline: 1-8micro gm/kg/min.
Isoproterenol: 1-4 micro gm/min.
Phenylephrine: 20-200 micro/min.

Cardiogenic Shock

  • Dobutamine and dopamine are used.
  • Venodilators nitroglycerine and nitroprusside.
  • Circulatory assist devices.
  • Intra aortic balloon counter pulsation.
  • Extracorporeal membrane oxygenator (ECMO).
  • Surgery for ruptured papillary muscle, acute MR, rupture of IV septum, MI.

Septic Shock

  • Large volume of IV fluid.
  • Antibiotics.
  • Surgical drainage of abscess.
  • Corticosteroids in moderate doses may be needed.