TRAUMA

Drowning and immersion

injury
Gary Minto
Will Woodward

Drowning is defined as death following asphyxia as a consequence

of submersion or immersion (partial submersion) in liquid. Near
drowning has been used to describe the survival of a patient for
longer than 24 hours following submersion, however, most authori-
ties recommend that the term no longer be used because some of
these patients eventually die.
Worldwide, up to 450,000 people die annually as a result of
drowning; at least twice that many are involved in non-fatal sub-
mersions. Half of the victims are children, predominantly unsuper-
vised toddlers. The second peak of incidence is in adventurous or
inebriated adolescent males. Drowning may follow a precipitating
event, particularly in adults:
• primary neurological event (seizure, syncope, stroke)
• primary cardiac event (myocardial infarction, arrhythmia)
• impairment of judgement, conscious level or motor ability by
drugs, alcohol or hypothermia
• trauma (cervical spine injury is a particular hazard in shallow
water incidents)
• foul play (child abuse, murder attempt, suicide).

Pathophysiology
The pathophysiology of drowning is related to the multi-organ
effects of hypoxaemia. The primary determinant of outcome
is the occurrence of circulatory arrest, indicative of prolonged
asphyxia.
Immersion effects – voluntary breath-holding occurs on initial
submersion. This may be accompanied, especially in young chil-
dren, by the diving reflex: intense peripheral vasoconstriction that
promotes bradycardia and preferential blood flow to the heart and
brain. At the break point of breath-holding, involuntary gasping
occurs and water inhalation occurs. Unconsciousness, progressive
bradycardia, asystole and death are inevitable without rescue. If
the victim is retrieved from the water and resuscitated, widespread
organ dysfunction can be expected. Individuals who drown in

Gary Minto is an Advanced Trainee in Intensive Care in the South West

Region, UK. He qualified from the University of Cape Town, and trained
in anaesthesia in London, Australia, and the South West. His interests
include therapeutic hypothermia and the intensive care management of
acute trauma.

Will Woodward is Consultant in Anaesthesia and Intensive Care Medicine

at the Royal Cornwall Hospital, Truro, UK. He qualified in Sheffield and
trained in general practice before deciding on his present career. His
interests include nutrition and outcomes in long-stay ICU patients.

ANAESTHESIA AND INTENSIVE CARE MEDICINE 6:9 321 © 2005 The Medicine Publishing Company Ltd
 TRAUMA

cold water (< 20oC), particularly small children, rapidly develop

hypothermia, which may confer some neurological protection. Rewarming techniques for the critically ill
Immediate care A 60 kg subject with an average specific heat capacity of
It is advisable to lift the victim out prone, to counter the possibility 0.83 kcal/kg/°C requires 300 kcal of heat energy to raise his
of sudden circulatory collapse on release of external water pressure. temperature from 28 to 34°C
Patients who remain conscious are likely to do well. Wet clothing
should be removed to allow insulation with thick blankets. This Passive
facilitates spontaneous rewarming via shivering thermogenesis. • Remove wet clothing, insulate with blankets
It may be difficult to distinguish bradycardia from asystolic Useful to limit further heat loss in the pre-hospital phase. Average
cardiac arrest in the hypothermic, comatose victim. Immediate rate of temperature rise < 0.5°C/hour; in cases other than mild
(bystander) cardiopulmonary resuscitation (CPR) efforts are crucial hypothermia active techniques are required
to outcome and such efforts are to be encouraged where doubt
exists. Unconscious patients are at high risk for aspiration of gastric Active
contents and should be intubated by appropriate personnel, taking Peripheral (external)
care to immobilize the cervical spine. • Forced air warming blanket, hot water bottles
An unconscious patient should be transferred to a facility Difficult to control. Can be counterproductive: peripheral
that can perform active core rewarming (Figure 1) as soon as vasodilatation can cause a secondary decrease in core
possible. temperature. Abolition of shivering may occur. Hyperkalaemia and
Hospital management acidosis may follow reperfusion of peripheries
Admission criteria – the decision to admit depends on whether
fluid aspiration has occurred. Symptoms and signs include haemo- Central (core) (ascending order of invasiveness)
ptysis, breathlessness and wheeze, tachypnoea, cyanosis, crackles • Warmed humidified inspired gases (‘cascade’ humidifier)
on chest auscultation, hypoxaemia, and radiographic abnormali- Maximum 45°C: delivers 10 kcal/hour, effective and safe
ties. Subjects who remain asymptomatic and free of clinical signs • Warmed intravenous fluids
at 4 hours can safely be discharged. Maximum 40°C: delivers 10 kcal/litre (all routes)
Decision to resuscitate – in cold water drowning, resuscitation • Warmed gastro-oesophageal lavage; bladder irrigation; pleural
should continue throughout attempts to rewarm. However, in cen- cavity lavage via chest drains
tres without access to cardiopulmonary bypass, restoration of the All intracavity methods may precipitate ventricular fibrillation
myocardium to a defibrillatable temperature may not be achieved. • Warmed peritoneal lavage or dialysis
In the event of successful return of spontaneous circulation it is Potassium-free dialysate, 40°C, short dwell time
suggested that active treatment be continued for at least 24 hours. • Intravascular Thermal Regulation System (Alsius CoolGard
No factors have been identified that accurately predict death or 3000®)
severe neurological impairment (Figure 2). There are reports of Controls temperature without removing the blood from the patient
intact recovery despite extreme physiological derangement. via a closed loop internal cooling circuit, the catheter cools or
Patients who arrive at the emergency department with pro- warms the patient’s blood as it circulates past the catheter
longed circulatory arrest following warm water (> 20oC) submer- • Extracorporeal circulation (haemofiltration or cardiopulmonary
sion have a dismal prognosis. bypass)
Therapeutic goals Haemofiltration circuit delivers about 120 kcal/hour at 200 ml/
• Initiate support of airway, breathing and circulation. min. Cardiopulmonary bypass obviates need for CPR and affords
• Commence rewarming using peripheral and core techniques as most effective control over rewarming rate (up to 3000 kcal/hour)
appropriate. and metabolic fluxes (e.g. potassium)
• Prevent secondary brain injury by providing optimal conditions
for cerebral oxygen delivery.
• No specific hospital interventions have been shown to alter 1
outcome. Supportive treatment is indicated for acute lung injury
and other organ dysfunction. hours. This requires intubation, ventilation, sedation and possibly
Rewarming – restoration of body temperature is a key aspect of neuromuscular blockade to prevent shivering.
management. Techniques to achieve this are outlined in Figure 1.
In circulatory arrest below 28oC, the myocardial temperature must Organ damage and treatment
be raised as soon as possible for successful defibrillation. This Cerebral damage – irreversible neuronal cell death begins
can be accomplished only through active core warming. Follow- within 5 min of inadequate cerebral oxygen delivery. Significant
ing return of spontaneous circulation a controlled restoration of primary brain injury promotes cerebral oedema, peaking in severity
body temperature towards normal is desirable. Pyrexia must be at 24–72 hours after the initial event. The established principles
actively prevented because it may exacerbate cerebral injury due of nursing at 30o head-up tilt, ventilation to low normocapnia and
to the associated increase in cerebral metabolic rate. The World control of cerebral perfusion pressure to greater than 70 mm Hg
Congress on Drowning (2002) recommends that victims who should be followed. Intracranial pressure monitoring has not been
remain comatose should be treated with induced mild hypothermia shown to improve outcome after drowning, but may provide useful
(32–34oC), initiated as soon as possible and sustained for 12–24 information. Depending on the history, an early CT scan may be

ANAESTHESIA AND INTENSIVE CARE MEDICINE 6:9 322 © 2005 The Medicine Publishing Company Ltd
 TRAUMA

useful to exclude a primary neurological cause. Seizure activity

Predictors of outcome1 must be controlled promptly with benzodiazepines.
Pulmonary effects – immediate local effects of water aspiration
At scene (salt or fresh) include bronchospasm, abnormal blood flow distri-
• Immersion > 5–10 min bution, pulmonary oedema and ventilation–perfusion mismatch.
Submersion time is usually an estimate, despite this it is a good Pneumonitis may follow aspiration of swimming pool chlorine
surrogate of asphyxia time and correlates well with outcome or vomitus. Systemic steroids are not useful in treatment. Up to
• Presence of cardiac arrest 70% of symptomatic survivors develop acute lung injury or acute
Survival in individuals maintaining spontaneous circulation is respiratory distress syndrome, through loss of surfactant function
> 98% , compared with 20% in those who lose their output leading to reduced compliance, segmental alveolar collapse and
• Bystander CPR transcapillary fluid leak. Management of the consequent hypox-
Bystanders may be dismayed by the appearance of the victim and aemia requires supplemental oxygen and a protective ventilation
erroneously consider resuscitation efforts to be futile. Studies strategy, though permissive hypercapnoea may be contraindicated
suggest that the only victims who survive are those who are if cerebral oedema is present. Blood gas interpretation is compli-
immediately resuscitated at the scene. cated by the increased solubility of O2 and CO2 in cold blood. To
• Water temperature avoid missing significant hypoxaemia it must be appreciated that
The classification of drowning as warm or cold depends on the the true in vivo PaO2 in a cold patient is lower than that measured
temperature of the water (> or < 20°C), not the victim. Rapid at normothermia. PaCO2 and pH corrected to 37oC are an accept-
brain cooling in icy water may be protective. There are a few able guide to interventions.
reports of children surviving intact after long submersion in water Cardiovascular system – the ECG in hypothermia characteristi-
< 5°C. However, if a victim has been submerged in water cally shows bradycardia, progressing to complete heart block at
> 5°C for longer than 25 min, the outcome is death or a lower temperatures. A positive deflection after the QRS complex,
persistent vegetative state the J wave, may appear. Below 28°C refractory ventricular fibril-
lation commonly supervenes. Extravasation from systemic and
On arrival at emergency department pulmonary capillaries promotes hypovolaemic shock, exacerbated
• Asystole on arrival/CPR duration > 25 min by cold diuresis (renal inability to conserve water). A systemic
Severe asphyxia likely inflammatory response syndrome (SIRS) with profound vasodilata-
• Dilated, non-reactive pupils and arterial pH < 7.0 tion may occur following resuscitation. Rapid volume expansion is
Acidosis and lactataemia usually correlate with poor outcome in necessary. If severe acidaemia and hypothermia are present, they
cardiac arrest. However, in drowning these are due to extremely accentuate the low cardiac output state. Lactic acidosis normally
acute cellular hypoxia. Rapid restoration of perfusion may reverse corrects spontaneously over several hours following restoration of
these profound metabolic derangements quickly. Thus initial pH tissue oxygen delivery. Failure to do so despite adequate volume
and lactate levels are of doubtful significance replacement suggests renal, hepatic or bowel ischaemia.
• Dilated, non-reactive pupils and Glasgow Coma Score < 5 Infection – stagnant water is colonized by Gram-negative
Suggests severe primary brain injury bacteria and more unusual pathogens. Aspiration of such fluid
• Poor Paediatric Risk of Mortality (PRISM) score promotes pneumonia and may lead to systemic infection. Pro-
Despite case reports, age has no independent association with phylactic antibiotics are of unproven benefit but are prudent if
outcome. PRISM score < 16 implies negligible risk, a score > 24 the subject was submerged in grossly contaminated water. Some
predicts death or severe neurological impairment. In patients with authorities advise an outpatient chest radiograph after 2 weeks
intermediate PRISM scores, a reliable prognosis is impossible to for all patients.
establish. PRISM scoring at the time of admission to PICU is not
helpful Outcome
A quarter of hospital admissions alive at 24 hours ultimately die,
In the critical care unit and a further quarter have a poor neurological outcome. 
Formal neurological assessment should be deferred until 24 hours
after immersion
• Absence of purposeful motor response
GCS motor score < 5 indicates poor prognosis
• Absence of brainstem reflexes
Absent pupillary responses and spontaneous respiration.
Sedation modifies these signs

CT scan at about 36 hours, showing abnormality (e.g. loss of FURTHER READING

grey–white matter differentiation) is useful corollary evidence Harries M. Near drowning. Br Med J 2003; 327: 1336–8.
Idris A H, Berg R A, Bierens J et al. Recommended guidelines for uniform
1
The influence of varying levels of hypothermia on these predictors has not reporting of data from drowning: the ‘Utstein style’. Circulation 2003;
been well quantified.
108(20): 2565–74.
Joost J L M, Bierens J J, Knape J T, Gelissen H P. Drowning. Curr Opin Crit
2 Care 2002; 8(6): 578–86.

ANAESTHESIA AND INTENSIVE CARE MEDICINE 6:9 323 © 2005 The Medicine Publishing Company Ltd