Transcript Document 7167840

Drowning and Near
Drowning
KH Naghibi MD
Drowning
• Demographics
– 6,000 - 8,000 deaths per year
– The 3rd leading cause of accidental death
in USA
– The 2nd leading cause of death in children
– 25,000 rescues each summer on California
beaches
Drowning is...
• Death secondary to asphyxia
while immersed in a liquid,
usually water, or within 24
hours of submersion
Drowning
• Statistical Risk Factors
– Age: Youth 40% under 4 years old
– Location: Pools, bathtubs, lakes, rivers
– Sex: Male 3:1
– Time of year: Warm months
Drowning
• Unconsciousness
– Due to :
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Trauma
Seizure
Coma
Drug/Alcohol abuse
Near Drowning
• Statistical Risk Factors
– Predisposing Illnesses: Epilepsy, seizures
– Trauma: Diving and boating accidents, falls
– Mental impairment: Drugs and alcohol
Predisposing Factors
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Coma, seizures
Alcohol/Drugs
Exhaustion
Hyperventilation
Rapidly moving water
Predisposing Factors
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Poor swimming ability
Exhaustion
Panic
Hypothermia
Trauma
In drowning...
air hunger and usually panic
Reflex inspiratory efforts lead to aspiration of
water and laryngospasm
asphyxia and hypoxaemia / acidosis
Near Drowning
• Potential Fresh Water Damage
– Hypoxia
– Atelectasis
– Pulmonary Edema
– Hypotonic
– Hemolysis
• Lowered Na, Cl, and K
Strips surfactant
Pathogenesis 1
• Asphyxia, hypoxemia, hypercarbia, & metabolic
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
Pathophysiologic Changes
Neurologic Effects
• Cerebral edema 24 - 72 hours following
injury
• Loss of autoregulation of blood flow
• Reperfusion injury
Pathophysiology without aspiration
• Severe, persistent laryngospasm
• Anoxic seizures
• Death
Pathophysiology with aspiration
• Hypoxemia
– Asphyxia starts the Hypoxia
– Intrapulmonary shunting leads to further
hypoxemia
– Pulmonary damage continues the process
Pathophysiology with aspiration
• Hypoxemia
– Occurs whether or not patient aspirates
– 85-90% aspirate
– 10-15% DO NOT aspirate
COLD WATER
and
WARM WATER
drownings are different
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
Warm Water
• 20oC and above
• 72oF and above
• Lakes, ponds, quarries
Warm Water Submersion
Poor Prognosis
• In warm water submersion
– Submersion > 5 minutes
– Fixed and dilated pupils (in the ED)
– No CPR for 10 minutes or more
– pH less than 7.1 on arrival at hospital
– Need for in hospital resuscitation or
ventilation
• Severe neurologic impairment or
mortality is likely
Hot Water
• Body temperature and above
• Hot tubs, bath tubs, hot springs
Salt
vs
Fresh
There are REAL differences
Potential Fresh Water
Damage
• Hypoxia
• Atelectasis
• Pathogenic bacteria and impurities
lethal
• Produces greater long-term damage
due to salt in pulmonary edema
Wet Drowning
• Approximately 90% of drowning victims
– aspirate water
– vomit
– cough
– gasp
– flood lungs with water
Drowning Pathophysiology
• 3 Major metabolic abnormalities
– Anoxia
– Acidosis
– Hypercapnia
Pathophysiology
• Consequences of Aspiration
– 2.2 cc/kg
– 11 cc/kg
– 22 cc/kg
Hypoxia
Blood volume changes
Electrolyte changes
• Average aspiration is only 2-4 cc/kg
Initial Assessment and
Resuscitation
Restating the
obvious
Initial Assessment and
Resuscitation
• Specialized issues
– No Heimlich maneuver: thought to clear
airways of liquid obstruction
• Amount of fluid is usually small and nonobstructive
• May increase risk of aspiration of gastric
contents
• Do not waste time, correcting hypoxia is
paramount
Initial Assessment and
Resuscitation
• Threshold for intubation should be very
low
• Indications for intubation
– Arrest
– Loss of airway protective reflexes
– Deteriorating neurologic exam
– Severe respiratory distress or hypoxia
despite supplemental oxygen
– Hypothermia (core temperature < 30oC)
Cold water (<10°C) immersion is
different from that in warmer water
Hypothermia
• Cerebral blood flow decreases 6-7% per
1oC drop
• Negative effects include dysrhythmias,
increased blood viscosity
• Must be cold before hypoxic
In cold water...
Cold stress leads to:
• Respiratory and cardio-vascular
responses
• Gasp reflex
Initial Assessment and
Resuscitation
• Hypovolemia
• Marked vasoconstriction
• IV fluids
Labs & tests
• Very mild electrolyte 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
Laboratory
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Arterial blood gases
Electrolytes
BUN/ Creatinine
Platelets/ PT & PTT/ CBC
Serum & Urine Hemoglobin
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,
Cerebral edema and diffuse neuronal injury
Acute tubular necrosis
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
Brain therapy
• ICP monitoring - not indicated, typically irreversible 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
• 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
Recommendations
• Pre-hospital resuscitation, including early 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
– Testing such as brainstem evoked responses, EEG, and MRI
(not CT) may prove helpful for neurologic examination
Pediatrics, 1997 Christenson, Jansen, Perkins
Near Drowning
Pulmonary Injury
• Aspiration as little as 1-3 cc/kg can
cause significant effect on gas
exchange
– Increased permeability
– Exudation of proteinaceous material in
alveoli
– Pulmonary edema
– decreased compliance
ICU Management
Strategies
Intubation/Ventilation
Indications
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SpO2 < 90% on FIO2 > 0.6
PaCO2 > 50 with pH < 7.3
Increased work of breathing
Abnormal CNS exam
Treatment of near drowning victims, some important points:
• Immediate on site CPR is the key to increase the chance
of survival.
• DO NOT DO any specific maneuvers (Heimlich) to expel
water from the lungs.
• ED observation for 8 hours to screen for those requiring
hospital admission.
• Arterial blood gas analysis and chest x-rays are the most
reliable parameters.
• Warning of any pyrexial illness after discharge
(secondary pulmonary infection).
Resuscitation Fluids
• Current practice
– Normal Saline
– 5% Albumin
– 25% Albumin
– Lactated Ringers Solution
– Hypertonic Saline
• Choice dependent on provider, cost,
habit
Albumin Infusion During Injury
Proposed Mechanisms for Protection
• Anti-inflammatory agent
• Reduction of platelet aggregation
– Reduction of microvascular thrombosis
• Improved local blood flow
Albumin Infusion During Injury
Proposed Mechanisms for Protection
• Regulates pyruvate dehydrogenase
– Improved cellular bioenergetics
• Tabernero et al. Glia 1999
• Binds free calcium
– Directly decreases cellular injury
• Wortsman et al. Am J Physiol 1980
• Oxygen radical scavenger
– Loban et al. Clin Sci 1997
– Kooy et al. Crit Care Med 1995
Outcomes
Long Term Prognosis
• Overall, >15% survivors with significant
neurologic deficits
• Children with spontaneous, purposeful
movements and had a normal brainstem
examination at 24 hours progressed to full
recovery
• Those without these findings by 24 hours
suffered severe neurologic deficits or death
Outcome Measures
• Death
• Cardiovascular function as measured by:
– Blood pressure, heart rate, and initial arterial blood gas
measurements
– Echocardiogram
– Need and duration of inotropic support
• Need and duration of mechanical ventilation
• Modified Multi-organ Failure Score on Days 1, 2, 3,
and 7
– Serum Creatine
– Cardiac Troponin I
– Total Bilirubin
Outcome Measures
• Lengths of stay in pediatric intensive care unit
• Length of stay in hospital.
• Admission neurologic examination as measured by
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Glasgow Coma Scale score
pupillary reactivity
other brain stem reflexes
presence of apnea
• Magnetic resonance imaging and spectroscopy
abnormalities at post-arrest day 7.
• Pediatric Cerebral Performance Category Scale
Score (PCPCS) at 6 to 12 months post injury.
• Glasgow Outcome Score (GOS) on discharge from
PICU
GOS on discharge from hospital
Factors increasing the risk of drowning
Toddler and adolescent age groups
Pools / dams / drains etc in children
Water with currents / rips / waves
Colder water
Alcohol and drugs (esp. in men)
Associated head and neck injury
Fatigue
• In warm water – death from drowning, slow
onset hypothermia
• In cold water – stress response may cause
early death, so too can drowning, hypothermia
may be protective in total immersion,
hypothermia is a late (>30 mins ) cause of
death
Asphyxia
Laryngospasm maintained
Relaxation of the airway
Respiratory arrest
Water enters lungs
Cardiac arrest
Surfactant washout
V / Q mismatch*
“Dry drowning”
“Wet drowning”
*mechanism in fresh and salt water slightly different
Cardiac response to cold stress in the first
few minutes:
Total body immersion / face only immersion?
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Diving reflex
↓heart rate
↓cardiac output
↑mean arterial p.
↑total peripheral
resistance
NO
Sympathetic activation
∞ temp of water
• ↑heart rate
• ↑BP
• arrhythmias
The problem with looking well...
Aspiration of water can cause late complications:
• Neurogenic pulmonary oedema, Pneumonia,
SIRS, DIC, Haemolysis, Hepatic & renal failure,
bowel necrosis
• Plus complications of hypothermia
Assessing aspiration:
Historical factors
Prolonged head immersion
Period of apnoea
CPR required
Symptoms / signs
Cough,
breathlessness,
Retrosternal
discomfort
Cyanosis, tachycardia
Tachypnoea, wheeze
or
Crackles in chest
Pink frothy sputum
Immediate hospital management
• Assess and manage ABC
• 100% oxygen
• Pulse oximetry (watch for false readings caused by
peripheral shutdown and acidosis)
• ABGs, FBC, U&E
• CXR
• Observation
• Management of associated hypothermia
Pathophysiology with aspiration
• Pulmonary Edema
– Damage to Alveolar membrane
– Damage to pulmonary microcirculation
Clinical Manifestations
• Radiographic Changes
– Non-cardiac pulmonary edema with normal
heart size
– Perihilar pattern
– Seen in 1/3 to 2/3 of patients initially
Hypoxia
• Respiratory Management Objective
– Try to achieve a Pa O2 of 70-100 mm Hg
– 70% will require more aggressive therapy
PEEP
• Indicated when pO2 < 60 and FIO2 > 50
• Try to keep the pO2 at 75-90
• This prevents pulmonary edema and
ARDS ??? (acute respiratory distress
syndrome)
Experimental Therapies
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? Controlled hypothermia
? Calcium channel blockers
? Barbiturate coma therapy
? Hyperbaric oxygenation
? Hyperventilation
Prognosis
• Survival depends upon a variety of
interrelated factors
– Age
– Underlying disease
– Water type and temperature
– Duration of submersion
– Degree of hypothermia
Bad Prognostic Factors
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Older age
Warm water
Spinal cord damage
Inadequate CPR
Decorticate / Decerebrate
Unconscious
Septic tank
Good Prognostic Factors
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Older child or young adult
Cold water
Adequate CPR/on scene ACLS/BLS
Conscious
Short submersion
Healthy