What are the cardiovascular effects of drowning?

Updated: Jun 19, 2019
  • Author: G Patricia Cantwell, MD, FCCM; Chief Editor: Joe Alcock, MD, MS  more...
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Answer

Drowning may result in an acute asphyxial cardiac arrest, which emanates from hypoxemia that precedes the development of ischemia. This scenario results from initial cessation of gas exchange followed by worsening hypoxia and eventual cardiac arrest. Hypoxemia is the overriding insult.

Hypovolemia may be due to fluid losses from increased capillary permeability. Profound hypotension may take place during and after the initial resuscitation period, especially when rewarming is accompanied by vasodilatation. It is important to remain cognizant that many patients present with hypothermia due to prolonged submersion times rather than true cold-water submersion.

Myocardial dysfunction may result from ventricular dysrhythmias, pulseless electrical activity (PEA), and asystole due to hypoxemia, hypothermia, acidosis, or electrolyte abnormalities (less common). In addition, hypoxemia may directly damage the myocardium, decreasing cardiac output.

Pulmonary hypertension may result from the release of pulmonary inflammatory mediators, increasing right ventricular afterload and thus decreasing both pulmonary perfusion and left ventricular preload. However, although cardiovascular effects may be severe, they are usually transient, unlike severe CNS injury.

Primary arrhythmias, including long-QT syndromes (particularly type I) and catecholaminergic polymorphic ventricular tachycardia (CPVT), may predispose patients to fatal arrhythmias during swimming. Sudden, severe cardiovascular collapse in otherwise healthy patients with brief, witnessed immersion may be the result of existing cardiac conduction defects and may not represent secondary effects of immersion injury. [54] Swimming may serve as an arrhythmogenic trigger and result in the diving reflex, which can lead to autonomic instability. The diving reflex is elicited by contact of the face with cold water and consists of breath-holding, bradycardia, and intense peripheral vasoconstriction. The exertion associated with swimming may additionally result in predisposition to syncopal events.


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