Transcript Drowning

Drowning
Jana Stockwell, MD
Statistics
• 1995 data:
– >1000 kids <14 years old drown
– 60% <4 years old
• 2000 CDC data:
– 3,281 unintentional drownings in USA (adults & kids)
– averaging 9 people/day - not including boatingrelated incidents
• 2003 CDC data:
– For every child who drowns, 3 need ED care for nonfatal submersion injuries
– >40% of these children require hospitalization
2002 World Congress on Drowning
• Drowning = process resulting in primary
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respiratory impairment from
submersion/immersion in a liquid medium
Regardless of survival
Drowning without aspiration does not occur
Terms which are “out”
– Dry, wet, active, silent, secondary, near-drowning
1989-1998 CDC data
>75%ile of National avg
50-75%ile of National avg
25-50%ile of National avg
<25%ile of National avg
Groups at Risk (2001 data)
• Males: 78% of drownings in the United States
• Children: 859 children ages 0-14 years died
from drowning
– Drowning rates have slowly declined
– 2nd-leading cause of injury-related death for kids ages 1-14
years
• African Americans: age-adjusted drowning rate
for African Americans was 1.4 X higher
(CDC 2003)
Morbidity & Mortality
• 15% of children admitted for drowning die in
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the hospital
As many as 20% of drowning survivors suffer
severe, permanent neurological disability
Drowning modalities
• Infants (age <1) -
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bathtubs, buckets &
toilets
Children ages 1-4 years swimming pools, hot
tubs & spas
Children ages 5-14 years
- swimming pools &
open water sites
(Brenner 2001)
Bucket drownings
• ~300 children in the US since
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1984
7-15 months of age
24 to 31 inches tall
Bucket may contain water or
nasty cleaning fluid
Tub drownings
• Approximately 10% of childhood drownings
• Typically lacking adult supervision
• Do tub seats help?
Bathtub seats - ? or ?
• Not intended or marketed as safety devices
• Bathtub drowning deaths of infants aged 6-10 mo
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from 1994-1998
40 infant drowning deaths associated with bath
seats
78 deaths not associated with bath seats
~45% of infants in this age group use bath seats
Data suggests seats either have no effect or they
may provide some slight protection against
unintentional bathtub drowning risks
Odds ratio 0.6 [95% CI 0.4-0.9]
Data: US Consumer Product Safety Commission & National Center for Health Statistics for US resident infants (1994-1998)
Tub seat use
Baby swim classes
• Done to “teach” babies to float
• No reported drownings in class
• Several reports of hyponatremic seizures
following class (How was school today?)
• False sense of security?
Pool/Spa drownings
• Most residential pool drownings are in kids <4 yo
• 3,000 pool drownings require hospital ED treatment
each year
– last seen inside the home
– missing from sight <5 minutes
– in the care of one or both parents at the time of the
drowning
• >50% occur in the child's home pool
• 1/3 occur at homes of friends, neighbors or family
• Since 1980, ~230 kids <4 yrs in spas & hot tubs
(Present 1987, Brenner 2001)
Cochran Review – Pool fencing
• Meta analysis of case–control studies evaluating
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pool fencing
Results:
– Pool fencing significantly reduces the risk of drowning
• Odds ratio (OR) for the risk of drowning or near drowning in a fenced pool
compared to an unfenced pool is 0.27 (95% CI 0.16 – 0.47)
– Isolation fencing (enclosing pool only) is superior to perimeter fencing
(enclosing property and pool)
• OR for the risk of drowning in a pool with isolation fencing compared to a
pool with three – sided fencing is 0.17 (95% CI 0.07 – 0.44).
• In-ground swimming pools without complete 4-
sided isolation fencing are 60% more likely to be
involved in drownings than those with 4-sided
isolation fencing
Boat-related drownings
• 2002 Coast Guard data, all ages:
– 5,705 boating incidents: 4,062 injured, 750 killed
– 70% of fatalities due to drowning
– 30% of fatalities due to trauma, hypothermia, CO
poisoning, or other causes
– Alcohol was involved in 39% of fatalities
– Open motor boats - 41%
– Personal watercraft – 28%
Alcohol
• Involved in 25-50% of teen and adult deaths
associated with water recreation (Howland 1995; Howland &
Hingson 1988)
• Alcohol influences balance, coordination, and
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judgment, and its effects are heightened by sun
exposure and heat (Smith and Kraus 1988)
Relative risk of drowning was 31.8 in persons
with a markedly elevated alcohol level (>21.7
mmol/L) and 4.6 for levels <21.6 mmol/L
(Cummmings JAMA 281:2198, 1999)
The event, part 1
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Voluntary breath-holding
Aspiration of small amounts into larynx
Involuntary laryngospasm
Swallow large amounts
Laryngospasm abates (due to hypoxia)
Aspiration into lungs
The event, part 2
• Decrease in sats
• Decrease in cardiac output
• Intense peripheral
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vasoconstriction
Hypothermia
Bradycardia
Circulatory arrest, while VF rare
Extravascular fluid shifts, diuresis
Diving reflex
• Bradycardia, apnea, vasoconstriction
• Relatively quite weak in humans
– better in kids
• Occurs when the face is submerged in very cold
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water (<20°C)
Extent of neurologic protection in humans due to
diving reflex is likely very minimal
Pathogenesis 1
• Asphyxia, hypoxemia, hypercarbia, & metabolic
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acidosis
Fresh water vs salt water - little difference
(except for drowning in water with very high
mineral content, like the Dead Sea)
Hypoxemia
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Occlusion of airways with water & particulate debris
Changes in surfactant activity
Bronchospasm
Right-to-left shunting increased
Physiologic dead space increased
Pathogenesis 2
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Cardiac arrhythmias
Hypoxic encephalopathy
Renal insufficiency
Global brain anoxia & potential diffuse cerebral
edema
Findings at autopsy
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Wet, heavy lungs
Varying amounts of hemorrhage and edema
Disruption of alveolar walls
~70% of victims had aspirated vomitus, sand,
mud, and aquatic vegetation
Cerebral edema and diffuse neuronal injury
Acute tubular necrosis
Signs & symptoms
• 75% of kids who develop sxs do so within 7
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hours of event
Coma to agitated alertness
Cyanosis, coughing, and the production of frothy
pink sputum
Tachypnea, tachycardia
Low-grade fever
Rales, rhonchi & less often wheezes
Signs of associated trauma to the head and neck
should be sought
Prevalence of concomitant
traumatic injuries
• 143 drowned & near-drowned
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kids
Median age 3.8 years (1 mo –
18.7 yrs)
30% with pre-existing disease
– CHD, sz, MR/CP, DD
• 5% with traumatic injuries
– All boys
– Older, mean age 13.5 years
– 6 of 7 had C-spine injury from
diving
(H Shofer, Ann Emerg Med 2004)
Labs & tests
• Very mild electrolyte
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changes
Moderate leukocytosis
Hct and Hgb usually normal
initally
– Fresh water aspiration, the
Hct may fall slightly in the
first 24 hrs due to hemolysis
– Increase in free Hgb without a
change in Hct is common
• DIC occasionally
• ABG – metabolic acidosis &
hypoxemia
• EKG
– Sinus tachycardia &
nonspecific ST-segment
and T-wave changes
– Reverts to normal within
hours
– Ominous - ventricular
arrhythmias, complete
heart block
• CXR
– May be normal initially
despite severe respiratory
disturbances
– Patchy infiltrates
– Pulmonary edema
Therapy for the lungs
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CPAP or PEEP
Aerosolized β-agonists for bronchospasm
Bronchoscopy
Prophylactic antibiotics have not been shown to
be beneficial
Steroids:
– No controlled human studies to support use
– Animal models and retrospective studies in humans
have failed to demonstrate benefit
Surfactant
• Beneficial
– Porcine surfactant
(Curosurf) 0.5 ml/kg
(40 mg/kg) IT for
ARDS 8h after
freshwater neardrowning in a 12yo
(Acta Anaesthesiol Scand 2004)
• Not beneficial
– Submerged rabbits
(A Anker, Acad Emerg Med 1995)
– Kids
(F Perez-Benavides, Ped Emerg Care 1995)
Brain therapy
• ICP monitoring - not indicated, typically irreversible
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hypoxic cellular injury
Brain CT – not indicated, unless TBI suspected
Mild hyperventilation?
Osmotherapy – not indicated
Corticosteroids (dexamethasone) - no proven benefit
Seizures - treat aggressively
Shivering or random, purposeless movements can
increase ICP
Hypothermia and barbiturate coma - highly controversial
& unlikely to benefit the patient (31 comatose kids, J Modell, NEJM
1993)
Bad prognostic indicators
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Submerged >10 min
Time till BLS >10 min
CPR >25 min
Initial GCS <5
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Age <3 years
CPR in ER
Initial ABG pH <7.1
Initial core temp <33o
Will the child die?
Neurologic prognosis
• Absence of spontaneous respiration is an
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ominous sign associated with severe neurologic
sequelae
Permanent neurologic sequelae persist in ~20%
of victims who present comatose
– Minimal brain dysfunction, spastic quadriplegia,
extrapyramidal syndromes, optic and cerebral
atrophy, and peripheral neuromuscular damage
Cold vs icy water immersion
• Usually hypothermia is an unfavorable sign
• Several case reports of dramatic neurologic
recovery after prolonged (10-150 min) icy
water submersions
– Freezing-temperature water (<5°C)
– Core body temperature less than 28-30°C, or much
lower
• For hypothermia to be protective, core
body temperature must fall rapidly,
decreasing cellular metabolic rate, before
significant hypoxemia begins
Hypothermia easier in kids
• High BSA/mass ratio and  subcutaneous fat
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insulation
Moderate hypothermia (core 32-35°C) VO2
due to shivering thermogenesis & increased
sympathetic tone
Severe hypothermia (core <32°C) shivering
stops & the cellular metabolic rate  (~7%/°C)
Hypothermia & brain protection
• Effective in protecting the brain and other
organs from anoxia for 75-110 min in controlled
circumstances where core body temperature is
cooled first to 18°C and then the heart is
stopped
– Deep hypothermic circulatory arrest (DHCA)
• Once cell death from hypoxemia occurs (~5-6
min), no protective hypothermic effect or
improve recovery
Hypothermia – surface cooling
• Surface cooling alone is cannot  core temp fast enough
to yield protection
• Cooling rate in drowning victims is difficult to estimate as
patient may also be swallowing or breathing in cold water
• Cardiac anesthesia literature:
– Surface cooling of anesthetized naked infants with ice packs and ice cold
water decreases rectal temperature by ~2.5 °C in the first 10 minutes
– Another 32 minutes for the temperature to fall to 24-26°C
– During surface cooling in flowing water at 1°C the nasopharyngeal
temperature of a naked infant (4 kg) falls 1°C every 5 minutes
• Hypothermic protection involving surface cooling only
would seem to require submersion in icy (not cold) water
Does aspiration of icy water will
accelerate the cooling process?
• 80-90% of animals & human submersion victims
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in warm or cold water drownings aspirate very
little (<2.2 ml/kg)
Theoretically, a very large quantity of icy water
would have to be aspirated or swallowed
Immersion in icy water results in involuntary
reflex hyperventilation and a decreased breath
holding ability to <10 sec, increasing the
likelihood of aspiration and rebreathing of icy
water in some victims
Ice water submersion - dogs
• Rapid & violent hyperventilation lasts ~70 sec
• Control animals submerged (ice water, head out
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of the water) carotid artery temp fell 0.8°C in 2
min
Completely submerged dogs temp fell ~8.0°C
during the first 2 min in both ice-water (4°C)
Rectal temp  lagged behind  in carotid temp
Victims of ice-water submersions more likely to
have involuntary breathing & aspiration
Brain may be cooled to a protective level
(~<30°C) provided the water aspirated was icy
& cardiac output lasts long enough for sufficient
heat exchange to occur
Cold water submersion - humans
• Few cold water victims have significant brain
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protection
Hypothermia is more commonly an unfavorable
prognostic sign
King County, WA (water is cold, but rarely icy)
– Hypothermic protection has not been observed
– 92% of good survivors had initial core temp of >34°C
– 61% of those who died or had severe neurologic injury
had core temp <34°C
• Finnish study:
– Median water temp 16°C
– Submersion duration <10 minutes had greatest
sensitivity in predicting good outcome, even in kids
Re-warming
• Re-warm 1-2oC per hour to range 33-36oC
• Mild (32-35o) passive rewarming
• Moderate (28-32o)
– Shivering fails
– J wave
– Active internal/external rewarming (not extremities)
• Severe (<28o)
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Appears dead, pupils dilated/NR
VFib, extreme brady, pulseless
Deep rectal or esophageal temps
Maintain CPR until core temp >32o
Warm water data - site
• 274 patients
• Age 6 months-15 years (mean 32 mos, median
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24 mos)
63% males
Submersion witnessed in 12% cases
Submersion site data (126 patients)
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80% backyard pool or spa
11% in a bathtub
5% in a lake or pond
3% in other sites
Warm water data - response
• Bystander resuscitation – 80% patients
• Average EMS respose time - 6.8 minutes
• Upon EMS arrival
– 76 (28%) children were in cardiac arrest
– 13 (5%) with PEA
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Paramedic CPR - 87/89 children
18 (20% of those w/ CPR) no longer needed CPR in ED
Paramedics intubated 19 children
Epinephrine in 30 patients
Warm water outcomes
• Cardiac
– 71 (80% of those in arrest @ scene) arrived to ED in
cardiac arrest
– 13 PEA
– 5 deteriorated & required CPR
– All 89 received Epi - (average duration 8.9 minutes,
range 2 to 105 minutes)
• 41 (46% of codes) survived (8 intact, 33 vegetative)
• Longest CPR duration in an intact survivor was 47 minutes
• Respiratory
– 125 (46%) patients were intubated
– 7 were apneic, 26 were breathing but comatose
Warm water outcomes
• CNS
– Persistent deficits in 15 of the 185 functionally intact
survivors
– Initial ED GCS 3 in 100 kids
• 14 survived intact
– 165 patients having GCS 4 upon arrival in the ED
• 2 survived in PVS
• all others survived intact
• 51 patients who subsequently died
– Withdrawal 22
– Brain death 23
All intact survivors demonstrated functional recovery
within 48 hours
Warm water survival in kids
• 6 studies reported functional recovery 17% (overall
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average) of victims who required CPR in the ED
Withholding or withdrawal of therapy from kids who have
low probability of functional survival after warm water
submersion injury has been suggested
– Failure to respond to advanced life support within 25 minutes
– Lack of purposeful movements or normal brain stem function @
24 hrs
– Anecdotal experience with spectacular recoveries & the small
numbers of severely injured patients in most studies raises
uncertainty about their predictive accuracy
• Graf et al. suggested that outcome for pediatric
submersion victims can be predicted with 4 measures:
coma, absence of pupillary light reflex, admission blood
glucose concentration (high) and sex
Recommendations
• Pre-hospital resuscitation, including early
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intubation, ventilation, vascular access, and
administration of advanced life support
medications
Continued resuscitation and stabilization in the
ED
Full supportive care in the ICU for a minimum of
48 hrs
Consider withdrawal of support if no neurologic
improvement is detected after 48 hours
– Ancillary testing such as brainstem evoked responses,
EEG, and MRI (not CT) may prove helpful to
1997 Christenson, Jansen, Perkins
corroborate the neurologic Pediatrics,
examination
You can’t make this stuff up
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67 year old with pulmonary fibrosis
S/P lung resection
On ward, with O2
POD#2 developed distress, to ICU, intubated,
ARDS…
Finally extubates…
(CHEST 2001; 120:1021-1022)
Part deaux – a better history
• Day after extubation, RN noticed patient's friend
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attempting to submerge the patient's face in a waterfilled basin
On questioning, patient indicated that he was aspirating
water to clean sinuses and lungs, explaining that this
was a daily routine for cleaning airways in his family
He noted that on POD 1, while performing this ritual, he
had a severe coughing and choking spell while his face
was submerged
This "technique" was witnessed by the housestaff, but
not reported until directly questioned