Volume 5, Case 15
Meri-Mika Morisada, MD
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
This is an 11-month old female who experienced a near-drowning episode in a bathtub. She had been placed in a bathtub approximately one-fourth full of water by her mother. Her mother then left the child unattended and went to the restroom herself. The child was behind the shower curtain. The mother was gone approximately five minutes, and upon returning she found the child floating in the water face up without any respiratory effort. She immediately grabbed the infant out of the bathtub, took her to the closest bed and attempted mouth-to-mouth resuscitation and some chest compressions. She called 911 at that time. Immediately prior to the arrival of the ambulance, the mother noted spontaneous respirations. Paramedics initiated positive pressure ventilation with a bag and mask apparatus. Five minutes later, they arrived at the E.D. at which time the infant was noted to be crying.
Exam: VS T 36.5, P 120, R 45, BP 130/50, oxygen saturation while on supplemental oxygen (exact FiO2 not known) and continuous positive airway pressure was 98%. She was crying and active. Head without signs of trauma. Eyes normal. Pupils equal and reactive. Neck supple. Heart regular. Lungs spontaneous respirations with bilateral wheezing and rales. Good air exchange. Abdomen benign. Extremities with good pulses and perfusion. No evidence of trauma. Neuro: active, crying, recognizes mother, interactive with mother. Muscle tone good. Cardiac and pulse oximetry monitors were placed.
A Foley catheter and nasogastric tube were placed. 200cc of fluid was evacuated from the stomach. Initial ABG: pH 7.11, pCO2 27, pO2 140, bicarb 9. Electrolytes Na 125, K 4.0, Cl 92, bicarb 11. Glucose 245. WBC 29,500 with 5% segs, 1% bands, 92% lymphs. Hgb 12.3, Hct 35.8, platelets 394,000. A chest radiograph was obtained.
View chest radiograph.
She was treated with sodium bicarbonate for metabolic acidosis, aerosolized albuterol for wheezing and furosemide for pulmonary edema. The CXR shows small patchy basilar pulmonary infiltrates.
She improves clinically and her chest radiograph is repeated two days later.
View follow-up chest radiograph.
Her chest radiograph is now normal.
Discussion
Drowning is defined as death within 24 hours as a result of submersion. "Near drowning" refers to survival beyond 24 hours of the submersion episode. The majority of accidents occur in swimming pools, ponds, lakes and bathtubs, with a peak incidence in children at less than 4 years of age and a second peak during the risk-taking age group of 15-24 years. Among boys 15-19 years, 38% of drownings are alcohol related.
Pathophysiologically, the problems commonly seen in a submersion accident are:
1. Hypoxia
2. Hypothermia (EXCEPT when submersion occurs in water greater than body temperature)
3. Aspiration (which can impair lung function and aggravate existing hypoxia after breathing is restored)
Hypoxia is the primary problem. The clinical manifestations of hypoxia are related to both the severity of hypoxia and the differing abilities of individual organs to tolerate hypoxia. The brain cortex is the first to sustain irreversible damage. The lower brain is next. The lungs and heart can tolerate up to 20-30 minutes of hypoxia and survive with appropriate post-rescue support.
Hypothermia: This phenomenon explains the good outcome of victims who are submerged in icy waters for up to 45 minutes (and occasionally longer). When submerged in icy cold water, the body temperature drops rapidly to a point where body activity and metabolism come to a virtual standstill. If this standstill develops before available oxygen is completely used, the hypothermia confers a protective effect. The remaining oxygen is used slowly and the body can survive submersion for a longer period of time before irreversible anoxic tissue damage develops. In most other instances, (non-icy water drowning), the victim's temperature will drop too slowly to confer any protective effect.
Aspiration: Experience indicates that saltwater and freshwater aspiration do not produce significantly different respiratory injury patterns. If large amounts are swallowed, hypo or hypernatremia may result from fresh or salt water submersions, respectively. Respiratory infection is possible, but antibiotics should be reserved for proven infection or when grossly contaminated water is aspirated.
Clinical Manifestations
In the first moments after rescue, the appearance of the child who has nearly drowned may range from apparently normal to apparently dead. Body temperature is frequently low, even in temperate, warm-water environments. Respiratory efforts may be absent, irregular, or labored, with pallor or cyanosis, retractions, grunting, and cough productive of pink, frothy material. The lungs may be clear, or there may be rales, rhonchi and wheezing. Infection may develop as a consequence of aspirated mouth flora or organisms in stagnant water, but this is not usually important in the first 24 hours.
Respiratory function may improve spontaneously or deteriorate rapidly as pulmonary edema and small airway dysfunction worsens.
Neurologic assessment may show an alert, normal child or any level of CNS compromise. A child may display agitation and combative behavior, seizures, blunted responsiveness to the environment, or profound coma with stereotypic posturing or flaccid extremities. Superficial evidence of head trauma may be noted in a few children whose submersion episode is a secondary event.
Conn and Baker devised a classification of submersion victims based on neurologic function since the CNS is the system most susceptible to damage from hypoxia. The classification is useful for 3 reasons: 1) it allows one to estimate the magnitude of the hypoxic insult; 2) it guides one in the selection of appropriate therapy; 3) it is highly predictive of patient outcome.
They suggest the classification be made on patient findings within the first hour of retrieval from water.
Patient classification by Conn and Baker divides the patient into categories A,B,C1-4.
Category:
A: Awake = Alert, fully conscious, minimal injury
B: Blunted = Obtunded to stuporous, normal central respiratory drive and other brain stem functions.
C: Comatose = Unarousable, abnormal brain stem function, abnormal central respiratory pattern, abnormal motor responses to painful stimuli. May have seizures. Respiratory failure present. Category C patients may be further subdivided:
C1: Decorticate. Flexor posturing. Cheyne-Stokes respirations
C2: Decerebrate. Extensor posturing. Central hyperventilation
C3: Flaccid. Apneustic or cluster breathing
C4: Deceased? Flaccid, apneic, no detectable circulation
Prediction of submersion victim outcome can be reduced to the following observation: If the victim has not sustained a cardiac arrest, the potential for intact survival is good when appropriate resuscitation and prehospital care are provided.
Patients in categories A and B almost uniformly do well with medical supportive therapy alone; intact survival is the rule. A few category B patients develop respiratory failure severe enough to require mechanical ventilation, usually from aspiration.
Patients in category C are in respiratory failure and require intensive therapy and monitoring. Patient outcomes vary. A very high percentage of category C1 and C2 have normal outcomes. A significant portion of C3 patients survive, but there is a substantial increase in their incidence of death or survival with anoxic-ischemic encephalopathy. C4 patients do poorly. The majority die or survive with profound anoxic-ischemic encephalopathy.
Note that all submersion victims may be apneic when retrieved from the water since apnea is a common reflex when the face is immersed in cold water even if they have not sustained a cardiac arrest. Since submersion victims with excellent prognosis may initially be found apneic, vigorous initial resuscitation measures should be attempted in all submersion victims. Our patient was a Category A patient and did quite well as predicted. The hypoxia was mild, and neurologic functioning was good. Although she was felt to have aspirated, antibiotics are reserved for proven infection or when grossly contaminated water is aspirated. For these reasons, this patient did not receive antibiotics. She was observed for 24 hours, as there may be a pulmonary inflammatory response 24-48 hours after the insult.
Immediate evaluation:
1. Consider: ABG, CBC, electrolytes, CXR.
2. Look for associated problems: head, neck, other injuries; ingestion; possibility of a seizure (primary or resulting from trauma, hypoxia, hyponatremia). Further tests after stabilization to be considered are CT scan of head, radiographs of the cervical spine, drug screen (eg., alcohol).
Management - Category A:
1. Supplemental oxygen.
2. Aerosolized beta-adrenergic agents for wheezing (albuterol).
3. Consider diuretic (furosemide) for pulmonary edema seen on CXR.
4. Sodium bicarbonate. Give 1 meq/kg for pH 7.1 or less. As oxygenation improves, the acidosis will also resolve.
5. Drying and warming measures.
6. Consider NG tube placement to prevent aspiration and decompress the stomach. Excessive stomach contents could elevate the diaphragm and restrict thoracic volume.
Management - Category B:
1. The above measures plus:
2. Intubation usually is not needed.
3. Electrolyte disturbances: Hyponatremia may occur if large amounts of fresh water are swallowed. Hypernatremia may occur if salt water has been swallowed.
4. Start an IV at maintenance or slightly less than maintenance to prevent further pulmonary compromise.
5. Consider antibiotics for aspiration of contaminated contents. Note that leukocytosis is a common stress response and is not indicative of infection.
Management - Category C:
1. Apply the above measures plus:
2. Intubate and ventilate, as all C patients are comatose and have respiratory failure. High distending pressures are usually required.
3. Monitor EKG for dysrhythmias. Hypotension may also occur.
4. In addition to sodium abnormalities, hyperkalemia from metabolic acidosis may occur.
5. Treat seizures (primary or from electrolyte abnormalities, hypoxia, trauma).
6. Hyperglycemia is a stress response. There is usually no need to treat this.
7. Leukocytosis, as mentioned, is an expected stress response. Leukopenia can occur in profound hypoxia. Consider antibiotics for aspiration of dirty water.
Prevention
1. Educate caretakers to potential submersion risks of bathtubs, water pails, pools, lakes, streams and the ocean. Stress the need for close supervision by a responsible adult.
2. Neighborhood and private swimming pools should ideally be surrounded by a double barrier (eg., two sets of fences). If a single barrier is used to surround the pool, the house should NOT be used as part of the barrier.
3. Encourage swimming lessons for all patients. However, water safety is not solely dependent on one's ability to swim. An overall understanding of water safety to avoid risk-taking behavior is necessary to minimize risk. For example, a 9-year old who can swim in a pool will easily drown in ocean surf or a rapidly flowing stream.
4. Encourage caretakers to learn CPR
References:
Aoki B. Evaluation, stabilization, and transportation of the critically ill child. Mosby Yearbook, 1992, pp.237-251.