John Fiske Brown Associates, Inc.

                                
 DROWNING, HOMICIDE AND MISADVENTURE:  WATER-RELATED ACCIDENTS AND CAUSE OF DEATH.

  L.L. Wickham, Ph.D.

How many times have you heard or read “death by misadventure” used to describe a drowning death in film or fiction?   Certainly it sounds more interesting than describing an accidental, unexplained or equivocal case as “death by mishap”.   Determination of whether a water-related death is intentional or accidental can be difficult and this provides fodder for the imagination of creative minds.  Was fair Ophelia, found floating with flowers in her hair, a victim of peaceful suicide, a false step, or violence?     Difficulties in drowning analyses may explain their popularity in the dramatic arts.

Drowning deaths are determined by process of elimination or exclusion of other causes.   Non-specific physical findings and circumstances or manner surrounding the discovery of the body rather than specific tests performed at autopsy are the usual determinants.  Bloody, foamy fluid may be present or absent in the respiratory tract.   Bloating from decomposition gases varies with time and temperature.  Skin wrinkling, stomach contents, and degree of rigor can all be used in the analysis.  Bodies may impact solid objects after death causing post-mortem wounds.  Water leaches blood from tissue over time making it difficult to say whether an injury happened before water exposure. “Critters” ranging from microbes to crabs, turtles, fish and other predators can also degrade the body and remove possible evidence.  Changes in blood electrolytes are considered unreliable indicators.  Chloride level differences in the heart, often cited as evidence, are not always present or specific to drowning   Tiny aquatic flora and fauna can be used as corroborating evidence but are not conclusive.  They are common throughout the environment and can contaminate samples.

 Some pathologists define drowning as death involving submersion in a fluid while most assume it means a person died from inhaling water.  However, some people drown without total immersion or without inhaling very much liquid.  Water can be absorbed from the lungs after drowning so the amount found postmortem can vary.  The salt content of the water [e.g. lake vs. ocean] does not affect survival.  Many factors contribute to a drowning including pre-existing pathology, age, water [fluid] temperature, and possible intoxication. Asphyxia, cerebral anoxia, or heart failure may be listed on the death certificate.

Fluid inhalation or suffocation by water usually results in heavy fluid-filled lungs [pulmonary edema].   Alternatively, the lungs may appear relatively “normal”, and it is hypothesized that temporary muscle spasm or obstruction of the larynx by mucous or vomit during submersion can cause “dry drowning”. When someone survives drowning for more than 24 hours the ambiguous term “near drowning” is often used even if they subsequently die.  Drowning usually involves at least partial immersion, breath holding, gasping for air, loss of consciousness, and death.   An individuals’ ability to breath-hold also varies with age, water temperature, and health status.  Three minutes is often cited as a “maximum” time limit for survival without breathing but this is variable.  Breathing is stimulated by carbon dioxide elevation, not reduced oxygen.  Some aquatic athletes hyperventilate prior to submersion hoping to increase underwater endurance.  Repeated, deep exhalation can result in reduced blood carbon dioxide levels and loss of consciousness [LOC] called “underwater blackout”.  Thus, aspiration of water during drowning may follow or precede LOC.  Historically, problems of fluid viscosity and the possible physical obstruction of lung airways by water were incorrectly thought to cause drowning.  However, patients with severe blood loss and infants with lung defects are successfully treated on a short-term basis by inhalation of fluid perfluorocarbons called “superoxygenated blood substitutes” disproving the old theory that fluids in the lungs necessarily cause drowning.

Cold water can increase the time a person survives drowning, as does immaturity.  This is due, in part, to a set of reflexes termed “the dive response”.  Decreased heart rate and reduced blood flow to the extremities reduce the amount of oxygen needed to survive.   Stimulation of sensory receptors on the face during head immersion in ice water can elicit the response. Children and conditioned adults often show a more pronounced effect.  Additionally, the body loses heat more quickly in liquid compared to air further slowing the metabolic rate.  A high surface area to volume ratio increases the effect [small & thin vs. large & round].  Low body temperature contributes to the seemingly incredible stories of children surviving over an hour in cold water after falling into an ice-covered pond. Cold or frozen water can also delay decomposition after a fatality and make time of death extrapolations based upon body temperature difficult.  Sudden immersion in cold water can also cause a sudden death from cardiac arrest, sometimes referred to as “immersion syndrome”, an ambiguous term that has also been used to describe military injuries caused by standing in cold water [e.g. trench foot].

Warm water deaths in hot tubs and Jacuzzis are also often complicated by age, disease and drug or alcohol abuse.  Healthy people rarely drown in such a situation.   Chronic degenerative disease, drinking alcohol or taking medication can predispose someone to hyperthermia [elevated body temperature] and syncope [LOC].   Typical scenarios include a person past middle age, often overweight, intoxicated with alcohol or marijuana “falling asleep” while soaking.  Death analysis may be complicated upon autopsy owing to pre-existing pulmonary or cardiovascular disease such as chronic obstructive pulmonary disease [COPD] or myocardial infarct [heart attack].  Homicide under these circumstances can be can be difficult or impossible to prove and easily assumed accidental if no physical evidence is collected or found.

Aquatic athletes, free divers or those using SCUBA also drown by “ natural causes”, pre-existing medical conditions, defective or improperly prepared equipment [e.g. insufficient or contaminated air sources], and environmental factors [storms preventing surfacing, physical entanglement or entrapment] or the effect of increased pressure [hyperbaria].   A big-wave surfer drowned recently when the leash connecting his ankle to his surfboard was entangled in rocks. The autopsy report later revealed significant cardiovascular disease.  Should the death be attributed to heart attack or drowning?  The result may depend on who is doing the analysis.