Drowning is a traumatic event, and is one of the major causes of morbidity and mortality in the pediatric population around the world. According to the World Congress on Drowning, it is described as the process of experiencing respiratory impairment from submersion /immersion in a liquid substance. This definition describes all forms of submersion injury that lead to respiratory impairment, including nonfatal events like near-drowning. Likewise, the term submersion that relates to drowning refers to the body being covered/under water. Warm drowning is classified as that which occurs at a water temperature of 20oC and cold drowning is classified as submersion in water less than 20oC. Males are usually four times more likely to be drowning victims. A study done in Canada in 2005 found that most drownings occurred in open area water, residential pools and bathtubs.1 It is believed that in most of the cases the event of drowning was preventable, and child neglect or abuse was usually implicated.
The pathophysiology of drowning is described as a process in which the victim’s airway moves below the surface of a body of water, then followed by an episode of apnea. Next, involuntary laryngospasm happens secondary to water present in the oropharynx or larynx. If the immersion event continues, then laryngospasm stops, and active aspiration of water starts, leading to damage of the victim’s airway and lungs. The surfactant in the lungs decreases and is destroyed as aspiration of water continues. Surfactant deficiency results in impairment of alveolar capillary gas exchange, intrapulmonary shunting, and pulmonary edema. Eventually, hypoxia leads to unconsciousness, apnea and cardiac arrest. This is a crucial moment that may determine the outcome of the situation, depending on how much time the victim was hypoxic and in cardiac arrest.
Aspiration of even a small amount (e.g.,1-3 ml/kg) of water results in considerably reduced lung compliance due to the altered surfactant function.2 If fortunately, the victim survives the drowning event, the medical team must be aware that they might have to deal with respiratory distress syndrome (RDS). This is due to the destruction of surfactant in the lungs and pulmonary edema caused by damage to the alveolar-capillary membrane. These factors will lead to respiratory failure in the infant if not treated properly.
In order to prevent respiratory failure, RDS and pulmonary edema should be treated. RDS will require management with mechanical ventilation, which has very good outcomes. The management must include lung protective strategy to mitigate the risk of ventilator associated lung injury. The key is to keep the PEEP at an optimal level to recruit collapsed alveoli, which improves gas exchange, leading to improved oxygenation. Low lung volumes and an adequate peak inspiratory pressure are essential components of a lung protective mechanical ventilation strategy to avoid any further lung injury. It is recommended that PEEP should be increased from 5 cmH20 with the goal of a PaO2/FiO2 ratio of 300 or more.3 This is thought to help with the regeneration of surfactant. The level of PEEP should be maintained for 24 – 48 hours before attempting to decrease it. A study done by Fan et.al, specifically recommended the use of high frequency jet ventilation with inhaled nitric oxide (NO-HFJV) for the management of pulmonary edema in pediatrics. They concluded that by using the NO-HFJV intervention, the PaO2, SaO2 and PH were higher and the survival time was longer.
To conclude, drowning is a preventable event among children that will impair the respiratory system and cause respiratory failure. It is imperative that adults carefully monitor children while they are around any body of water. The survival rates in drowning victims are improving due to advanced treatment options now available at trauma centers.
References:
1. Wintermute GJ: Childhood drowning and near-drowning in the United States ,Am JDis Child,112:440,2003
2. LeroyP, Smismans A, SeuteT.Invasive pulmonary and central nervous system aspergillosis after near-drowning of a child.Pediatrics 118:e509,2006
3. Fan Y, Dong W, He J, Du L, Xu G, Liu X, et al. The effect of HJ-1 NO–HFJV respirator on treating pulmonary edema caused by seawater drowning. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2002;19(3):526-528.
rayahaloush 