Drowning and Submersion Injury

Chapter 169 Drowning And Submersion Injury



Lisa Leigh Powell, DVM, DACVECC



KEY POINTS



• Drowning, or submersion injury, is a leading cause of morbidity and mortality in human patients.

• Reports of drowning or near-drowning injury in veterinary patients are sparse.

• The primary pathophysiologic abnormality seen in near-drowning victims is hypoxic tissue damage due to the inability to inspire oxygen and expire carbon dioxide.

• The goals of therapy include neuroprotective therapy, cardiovascular support, and an oxygen-rich environment.

• Prognosis in humans depends on submersion time, cardiopulmonary resuscitation time, and severity of acidemia.


DEFINITIONS


Drowning accounts for more than 500,000 human deaths annually, worldwide. This number is thought to be grossly underestimated, primarily due to underreporting in less developed countries. Catastrophic natural disasters such as tsunamis, hurricanes, and floods add to the number of injuries and deaths attributable to drowning and near-drowning events. In the United States, in 2002, drowning accounted for 775 deaths in children ages 1 to 14 years, representing the second leading cause of death for this age group.1 Because of the high incidence of drowning and near-drowning injury, a consensus conference was held to establish guidelines for uniform reporting of data from drowning incidents and to stratify definitions for drowning and its associated pathologic complications.2 In addition, a systematic review of 43 articles addressing the definition of drowning found 33 different definitions describing drowning incidents: 20 for drowning and 13 for near drowning.3


The Consensus Conference on Drowning published its recommended guidelines for uniform reporting of data from drowning in 2003.2 The following definitions were presented from the consensus conference for use in research and data reporting when associated with drowning and near-drowning victims:


• Drowning is a process resulting in primary respiratory impairment from submersion or immersion in a liquid medium. Liquid is present at the victim’s airway, preventing respiration of air. The victim may survive or die, but regardless of outcome, the victim has been involved in a drowning incident. This is in contrast to the definition proposed by the American Heart Association in 2000, reserving the term drowning for victims who die from water submersion within 24 hours of the event.4

• Dry drowning describes victims who do not aspirate liquid into the lungs, whereas wet drowning refers to aspiration of liquid. Victims of dry drowning often experience morbidity from laryngospasm, resulting in the same hypoxemic and hypercarbic state seen in those that have aspirated liquid.

• It was concluded in the consensus statement that near drowning be abandoned as a term used to describe victims of submersion injury that ultimately survive, because the term drowning is inclusive of both survivors and nonsurvivors. The term submersion victim was proposed as an alternative to near-drowning victim by the American Heart Association and still is in use.


INCIDENCE AND EPIDEMIOLOGY



Humans


The incidence of drowning and submersion injury remains high in humans. Drowning is the third most common cause of accidental death in humans younger than 44 years of age, with 40% of all drowning deaths reported in children less than 5 years of age.5 Another 15% to 20% of drowning victims are between the ages of 5 and 20 years, and male victims dominate in all age-groups.5 Most drownings occur in fresh water, with children younger than 1 year of age most often drowning in bathtubs, buckets, or toilets.6 Drowning most often occurs in residential swimming pools in children aged 1 to 4 years.7,8 In contrast, adolescents most often drown in rivers, lakes, and canals, and drug or alcohol use is a contributing factor in about 50% of these cases.9,10 Male individ-uals are thought to have a higher incidence of drowning, especially during adolescence, because of the tendency toward risky activities and overestimation of their swimming abilities.11


Factors associated with a higher risk of drowning in humans include the use of alcohol or recreational drugs, lack of supervision in children, and medical conditions such as epilepsy and long QT syndrome.12,13



Veterinary Patients


There are only two published reports of veterinary patients involved in drowning incident. The first is a case report of a gelding that recovered from a drowning incident in which he became entangled in a safety line attached to his harness while swimming in a chlorinated swimming pool. The reported adverse effects of the incident included metabolic acidosis, hypoxemia, and pulmonary infiltrates in the dorsocaudal lung fields. Successful therapy included antibiotics and bronchoalveolar lavage with surfactant.14


The second publication referring to drowning in veterinary patients describes animal abuse cases in a population of dogs and cats in the United Kingdom. In this sample of 243 dogs and 182 cats, drowning accounted for 3 of the feline abuse cases.15 Anecdotally, a drowning canine victim survived with high morbidity, developing secondary pneumonia (transtracheal fluid wash positive for Staphylococcus intermedius) and requiring a 7-day intensive care hospital stay with oxygen support.


The pathophysiology and clinical course of veterinary patients involved in drowning incidents probably correlates well with the human progression of injury, directing diagnostics, therapy, and outcome in canine and feline drowning victims.



PATHOPHYSIOLOGY OF INJURY



Pulmonary


Drowning occurs without aspiration of water in about 10% of victims, whereas 90% aspirate fluid into the lungs.16 All submersion victims experience hypoxemia, either from laryngospasm in which no aspiration occurs or aspiration of fluid resulting in loss of surfactant causing atelectasis and intrapulmonary shunt. Most (about 85%) submersion victims that survive are thought to have aspirated less than 22 ml/kg of water.16


Hypoxemia in submersion victims results from intrapulmonary shunting of blood. Bronchospasm, atelectasis due to surfactant washout, aspirated water or matter in the alveolar space, infectious or chemical pneumonitis, and acute respiratory distress syndrome (ARDS) all contribute to this shunting in submersion victims.17 An intrapulmonary shunt is defined as a portion of the cardiac output that enters the left side of the heart without being oxygenated in the lungs as a result of pathology of the lung parenchyma.18 There are three different types of intrapulmonary shunts: anatomic shunts, capillary shunts, and venous admixture.


Submersion victims may experience both the capillary and venous admixture types of shunting. Capillary shunts describe blood that passes through the lungs but does not get oxygenated because it does not respire with alveolar gas. In submersion victims that aspirate water into the alveolar space, surfactant washout causes atelectasis, resulting in capillary shunting. Venous admixture occurs when blood traverses the pulmonary capillaries and respires with alveoli that have low oxygen tension. This occurs primarily because of ventilation-perfusion inequality, which may be present in submersion victims that aspirate water or particulate matter.

Related posts:

  1. Deteriorating Mental Status
  2. Hyperthermia and Fever
  3. Ventilator-Associated Lung Injury
  4. Allergic Airway Disease in Dogs and Cats and Feline Bronchopulmonary Disease

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Sep 10, 2016 | Posted by in SMALL ANIMAL | Comments Off on Drowning and Submersion Injury

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