Near Drowning

 Near Drowning

PKGhatak, MD

Some drowning victims are rescued in time and revived by cardiopulmonary resuscitation (CPR). They are designated as Near Drowning.

  The World Health Organization reported 236,000 drowning deaths in 2019. Drowning is the 3rd leading cause of accidental death in the world. Many believe that the number is actually over 500,000 because of a lack of information from less developed countries.

  Submersion is when upper airways are underneath the liquid cutting off the air supply. Immersion is when the body is underneath the liquid and the upper airways are above the liquid maintaining an open path for air to reach the lungs. Both submersion and immersion generate a number of changes in the body, some are reflexes and others are biochemical and pathophysiological. Biological changes due to submersion are discussed here.

 Near Drowning may take place in warm water or cold water. The effects of water temperature have profound effects on the body.

 Diving Reflex.

 Disruption of air supply to the lungs in submersion causes a reflex attempt to breathe and a small amount of water enters the airway. That produces laryngospasm. The water in the airway immediately produces closure of the glottis. By these actions, further water entry into the lungs is prevented. The breath holding continues as long as the face is completely underwater. Subsequent events differ from warm water submersion and cold water submersion.

 The afferent nerve in the diving reflex is the sensory division of the Trigeminal and Glossopharyngeal nerves. The sensory information is related to the Nucleus Tactus Soliterious of the Vagus. The motor efferent action originates in the dorsal nucleus of the vagus and carries out by the recurrent laryngeal branch of the Vagus, and motor fibers of the Glossopharyngeal nerve. It results in the closure of the larynx and glottis,

 The autonomic efferent cholinergic fibers of the vagus to the heart originate in the nucleus ambiguous of the vagus and alpha1 fibers of sympathetic nerves to the artery and muscarine fibers of the vagus to the main pulmonary artery.

 Warm water submersion produces vasodilatation and hypotension; which result in sinus tachycardia and tachypnea.

 Coldwater submersion produces vasoconstriction and bradycardia, increases peripheral vascular resistance, reduces blood flow to muscles and proportionally increases blood flow to the brain due to cerebral hypoxia and hypercarbia.

 The respiratory center in the brain stem produces breath withholding as long as submersion continues. The aortic and carotid bodies sense hypoxia and produce vasoconstriction by alpha1 sympathetic nerves.

 Effect of Divining Reflex,

 Glottis closer prevents aspiration of water during submersion, slow heart rate decreases the oxygen demand of heart muscles. Increased arterial peripheral resistance decreases blood flow to muscles, lowering oxygen demand and redistribution of blood volume by increasing cerebral supply.

 Continued submersion produces cerebral anoxia, in spite of increased blood flow, and anoxia in vital neuronal centers results in the relaxation of muscles of the larynx and glottis, followed by water entry into the stomach and to the lungs. Underwater seizures may take place. Anorexic cerebral function loss is extensive, some are reversible others are not.

  Other injuries and effects of water submersion.

 Shallow water diving can produce fractures of cervical vertebrae, skull and ribs. Weeds and other vegetation may enter the mouth and throat. Fresh water in the lung alveoli washes away surfactant and leads to atelectasis. Saltwater pulls water from capillaries due to higher osmotic pressure and then destroys the surfactant. Atelectasis causes a mismatch of ventilation and circulation and increases intrapulmonary shunt. In general, about 100 to 200 ml of water entry in the lungs. That much water does not increase blood volume or electrolyte imbalance as previously thought, nor does significant hemolysis take place.

 Hypothermia is common and the core body temperature depends on the water temperature and duration of submersion. Effects on the heart in cold water submersion are sinus bradycardia, A-V nodal block, atrial tachycardia and atrial fibrillation; ventricular arrhythmias are less common. The cardiac arrest also happens.

 Bacteria, viruses and parasites are usually found in lakes and tanks. Various infections should be anticipated. Aspiration of gastric content happens during or after resuscitation and produces anaerobic pneumonia.

 Non-Cardiac Pulmonary Edema: In saltwater drowning hypertonic water draws water out of pulmonary capillaries and disrupts endothelial cells of alveoli capillaries. Plasma enters the alveolar space and pulmonary edema develops. The amount of seawater of 3 to 4 ml /Kg body weight can produce pulmonary edema,

 Cardiac collapse may develop after bringing the victim out of the water and cardiopulmonary resuscitation (CPR) started. In deep water drowning, water pressure around the thorax increases cardiac output. CPR increases cardiac output further causing cardiovascular collapse.

 CPR in Near Drowning is different from CPR for heart victims. The primary goal of CRP in Near Drowning is to correct hypoxemia as fast as possible and then correct other abnormalities deliberately paced and not so fast but are very vigilant and patients should be monitored continuously for cerebral hypoxia.

 Red Cross publicizes CPR instructions for the general public and provides advanced training for the first responders. CPR should be started as soon as the victim is brought to shallow water or on land by the rescuer and then call for help.

 No attempt should be made to drain water from the stomach. Those maneuvers only promote aspiration. Delay defibrillation because the carotid pulse is difficult to palpate on the cold and clammy skin of victims. Without an ECG (EKG) confirmation, no attempt should be made to diagnose asystole or VF (ventricular fibrillation), and the chilled heart does not respond properly to external electric jolts. Wet clothing should be removed and the body should be wrapped in a warm blanket.

 Warming the victim should only be done in hospitals equipped with extracorporeal heating and extrapulmonary membrane oxygenation facilities.

 All Near Drowning victims should be admitted to the hospital. Correcting hypoxia, hypercarbia, and acidosis in presence of cerebral anoxia calls for Pulmonary / Critical care specialists. One should not use PEEP (positive end respiratory pressure) without the input of PCWP (pulmonary capillary wedge pressure). Significant cerebral dysfunctions should be anticipated and addressed promptly and may require rehabilitation services upon discharge. Convulsion, hypoxia. Cerebral anoxia, hypotension, cardiac arrhythmia, pneumonia, and noncardiac pulmonary edema should be treated properly.

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