This document provides an overview of environmental medicine as it relates to drowning and electrical injuries. It defines drowning and discusses epidemiology, risk factors, pathophysiology, symptoms, diagnosis, treatment and prevention of drowning. Globally, drowning causes 380,000 deaths per year. Risk factors include lack of supervision for children and alcohol use for adults. Pathophysiology involves laryngeal spasm and hypoxia/asphyxiation. Treatment focuses on rescue breathing, warming, and monitoring for complications. Prevention strategies target child supervision and barriers around pools. The document also covers definitions, pathophysiology involving current strength and duration, symptoms, diagnosis, and treatment of electrical injuries as well as prevention through insulation and circuit breakers

1. Environmental Medicine: Drowning &
Electrical Injuries
DR OPEYEMI CM
SENIOR REGISTRAR
SUPERVISING CONSULTANT
PROF SALAMI AK

2. Outline
• Definition/Introduction
• Epidemiology
• Risk factors
• Pathophysiology
• Symptoms & Signs
• Diagnosis
• Treatment
• Prognosis
• Prevention

3. DROWNING
DEFINITION
• Drowning is defined as respiratory impairment resulting from submersion in a liquid
medium
• Drowning can be nonfatal (also called near drowning) and fatal
• About 4 times as many people are hospitalized for nonfatal drowning as far fatal
drowning
• Intentional use of drowning (water boarding) in humans is unethical and is classified as
torture in Geneva Conventions

4. Introduction
• Generally, drowning accidents results in asphyxiation & hypoxia, which can damage
multiple organs and lead to death if the victim is not rescued
• In the adults, drowning is common in pools, hot tubs, and natural water settings
• Among infants and toddlers, drowning is common in toilets, bathtubs and buckets of
water

5. Epidemiology of drowning
• WHO estimates 380,000 drowning deaths worldwide each year
• 1st cause of accidental deaths in preschoolers
• 2nd most common cause of accidental death in school-age children ages <14yrs
(particularly in ages <4yrs)
• Overall, drowning is the 3rd leading cause of accidental death in the US
• >50% of drowning leading to deaths occur in swimming pools

6. Epidemiology of drowning
• Children aged 1-4yrs often drown in swimming pools
• Infants <1yr usually drown in bathtubs
• Children >15yrs, 65% of drowning occur in natural water (river, lakes, ponds,
oceans)
• Alcohol is a factor in >50% of adolescents & adults drowning deaths
• About 4 times as many people are hospitalized for non-fatal drowning as for fatal
drowning

10. Risk factors for drowning
• Infants & Children
– Lack of adequate supervision of children in bathtubs & swimming pools
– Child abuse/neglect
– Lack of life jackets in swimming venues
– Children <4yrs
– African-American/Immigrant families

11. Risk factors for drowning
• Teenagers & Adults
– Males > Females
– Alcohol abuse
– Inability to swim
– Fatigue/exhaustion when swimming
– Suicide attempts
– Medical emergency in water
• Myocardial infarction, seizures, hypoglycemia, fatigue or exhaustion in water
– Lack of life jackets in swimming venues
– Known or unknown Long QT syndrome (LQT1)

12. Drowning types
• Drowning is classified into 2
– Wet drowning (80-90%)
• There is aspiration of water into the lungs
– Dry drowning (10-20%)
• There is no aspiration of water into the lungs
• There is reflex laryngeal spasm
• There is no clinical difference in prognosis, treatment and outcome between wet &
dry drowning

13. Pathophysiology of Drowning/The ‘drowning’ sequence
– Drowning victims are always terrified & they struggles to keep his/her head
above the water
– After the head submerges or drops below the water surface, breath holding occurs
– The overwhelming sympathetic overdrive with breath holding causes the larynx
to go into spasm
– Most often (80-90%) the laryngeal spasm relaxes allowing water through the
larynx into the lungs(wet drowning)
– Approximately 10-20% of drowning victims have persistent laryngeal spasm and
no fluids is found in the lungs at autopsy (dry drowning)

14. Drowning Victims

15. Pathophysiology of Drowning/The ‘drowning’
sequence
• The overall mechanism of demise from drowning is via larngeal spasm leading to
asphyxiation which subsequently precipitates respiratory arrest & cardiac arrhythmia
leading to death
• The brain stops functioning with permanent cortical damage occurring within 4-
6mins if not rescued

17. Pathophysiology of Drowning
Hypoxia & Metabolic acidosis
1. Asphyxiation from laryngeal spasm of drowning leads hypoxia.
2. Immediate hypoxia occurs from aspiration of water.
3. Fresh/sea water aspiration destroys pulmonary surfactant leading to alveolar collapse,
V/Q mismatch & hypoxemia
4. Aspiration of hypertonic sea water pull additional fluid into the alveoli leading to
alveolar edema with further V/Q mismatch
5. Generalized tissue hypoxia leads to metabolic acidosis
Hypothermia (temperature < 35°C)
1. Exposure to cold water leads to systemic hypothermia. Systemic hypothermia can be
initially protective by stimulating the mammalian diving reflex slowing the heart beat
and constricting the peripheral blood vessels shunting oxygenated blood away from
the extremities and the gut to the heart and brain possibly prolonging survival and
delaying the onset of hypoxic tissue damage.
2. Prolonged hypothermia becomes deleterious to the tissues

18. Pathophysiology of Drowning
Fluid aspiration
1. Enough large volume of fluid are sometimes aspirated to cause change in
blood volume and electrolyte concentraions
2. Sea water aspiration may increase Na and Cl slightly. Large volume of
aspirated fresh water can decrease electrolyte concentration significantly to
cause hemolysis
Associated injuries
1. It is important to look for skeletal, soft tissue, head and internal injuries in
drowning victims.
2. People who dive into shallow water may sustain cervical and other spine
injuries

19. Symptoms & Signs of Drowning
– Panic+++
– Air hunger
– Tachypnea
– Chest retractions
– Cyanosis
– After rescue
• Anxiety, vomiting, wheezing, altered consciousness

20. Diagnosis of Drowning
• Most people are FOUND IN OR NEAR WATER making the diagnosis obvious
clinically
• Cervical spine injury is assumed especially if there is history of diving into shallow
water
• Sometimes respiratory symptoms are delayed until several hours after
submersion/drowning episode

21. Investigation of Drowning victims
Investigations are to identify complications/associations of Drowning
• Pulse oximetry to determine the severity of asphyxia/hypoxia
• Body temperature to rule out hypothermia
• Random Blood Sugar to rule out hypoglycemia
• Arterial Blood Gas if oximetry is abnormal
• ECG to rule out presence of arrhythmia/LQT syndrome in patient who drown
without apparent risk factors
• Cardiac Enzymes
• CXR
• Cervical Spine Xray
• EUCr

22. Treatment of Drowning patients
• All patients are to the transported to the hospital and observed for several 12-24hrs
because respiratory symptoms can be delayed
• Hospital admission is recommended except in patient with mild symptoms and normal
oxygenation in the emergency
• Initiate Resuscitation measures immediately
– Airway
– Breathing
– Circulation
– Core Body temperature

23. Treatment of Drowning patients
• Reverse hypoxia with 100% Oxygen via facemask or Endotracheal tube placement
ASAP and titrate with oximetry
• Warm hypothermic patients with aluminium foil ASAP
• Mechanical ventilation with PEEP/IPPV to expand collapsed alveoli (atelectasis) to
aid resolution of pulmonary edema
• Nebulized β2 agonists to reduce bronchospasm & wheezing
• Antibiotics in patients with bacteria pneumonia from aspiration

24. Prognosis of Drowning
• Depends on timeliness of rescue
• Effectiveness of emergency response
• Rapid institution of resuscitation (most important factor) (good prognosis)
• Brief duration of submersion (good prognosis)
• Young age (good prognosis)
• Cold water temperature (mammalian diving reflex) (good prognosis)

25. Complications of Drowning
1. Respiratory failure
2. Acute Respiratory Distress Syndrome
3. Aspiration/chemical pneumonitis
4. Aspiration pneumonia
5. Subsequent Aquaphobia
6. Post traumatic stress disorder

26. Prevention of Drowning
• Don’t use alcohol/drugs before or during swimming
• Children or inexperienced swimmers should swim in guarded/supervised areas only
• Children <4yrs, swimming lessons not recommended
• Household swimming pools should be surrounded by a gated fence >1.5m
• Elderly people with debilitating illness that can alter consciousness should take extra
precautions during swimming

27. Electrical Injuries/Electrocution

28. Electrical Injury
• Electrical injury is tissue or organ damage caused by generated electrical current
passing through the body
• Accidental electrical injuries in the home rarely result in significant injury or sequele
• However, accidental exposure to high voltage in the workplace causes about 400
deaths in the USA
• Electrocution is the killing of a person with passage of high voltage current through
the body

29. People in which electrical injury are exceptionally
dangerous
• Persons with Arrhythmia
• Persons with Chest pain
• Persons with known or risk with of heart disorders
• Pregnant patients

30. Pathophysiology of Electrical Injury
• Traditionally, the severity of electrical injury depends on
Kouwenhoven’s factors
– Type of current (DC/AC)
• AC is 3-5 times more dangerous compared to DC for the same voltage & amperage
– Voltage & amperage
• Measures of current strength
– Duration of exposure
• Longer duration increases injury severity
– Body resistance
– Pathway of current
• Determines the specific tissue damaged
• Electrical field strength (a newer concept) seems to predict injury
severity more accurately

32. Pathology of Electrical Injury
• Application of low electrical field strength causes immediate unpleasant feeling of
being ‘shocked’ but seldom results in serious or permanent injury
• Application of high electrical high strength may cause thermal or electrochemical
damage to internal tissues e.g.
– Hemolysis
– Tissue protein coagulation
– Muscle necrosis/swelling
– Tissue destruction &
– Ventricular fibrillation

35. Symptoms & Signs of Electrical Injuries
• Severe Burns
• Severe involuntary muscular contractions
• Seizures
• Ventricular fibrillation/Cardiac arrest
• Respiratory arrest
• Muscle paralysis
• Spinal cord & peripheral nerve damage
• Fall/injuries

39. Diagnosis of Electrical Injuries
• History & essentially eye witness
• Head-to-toe examination
• ECG
• Cardiac enzymes
• Urinalysis
• EUCr

40. Treatment of Electrical Injuries
• First priority is to break contract between the person & the current source by
shutting off the current
• Resuscitation
• Analgesics
• Cardiac monitoring for 6-12hrs
• Wound care of Burns

43. Prevention of Electrical Injury
• Electrical devices should be properly insulated and grounded
• Incorporate protective ground fault circuit breakers which trip when as little as
5mA of current leaks into the ground
• Outlet guards reduces risks in home with infants and children

44. Thank You