Study Notes on Near Drowning

Definition: 10-15% of victims do not aspirate fluid into their lungs.
- Result of acute asphyxia brought on by laryngospasm or prolonged breath-holding.
- Mechanism: Glottis spasms and prevents water from passing into the lungs.

Definition: Death by suffocation resulting from submersion.
- More frequent in fresh water, with 85-90% of drowning victims aspirating fluid into their lungs.
- Typically less than 22 ml/kg worth of fluid is involved.
- Mechanism: Glottis relaxes, allowing fluid into the lungs.

Initial Response: When fluid is inhaled, bronchial walls constrict due to a parasympathetic reflex.
Non-cardiogenic pulmonary edema: Fluid moves from pulmonary capillaries into the bronchioles, alveoli, leading to swelling.
Effects:
- Decreased surfactant leads to increased surface tension and alveolar instability.
- Laryngospasm: Interstitial edema leading to engorgement of perivascular and peribronchial spaces.
- Frothy, white, and pink secretions throughout the tracheobronchial tree.
- Alveolar shrinkage, atelectasis (collapse of lung tissue), and consolidation.
- Bronchospasm may also occur.

Demographic Data:
- 50% of all adult drowning victims have used alcohol.
- Approximately 80% of drowning victims are male.
- Highest incidence found in males aged 10-19 years.
- African-American children: 4.5 per 100,000 annually (freshwater lakes and ponds).
- Caucasian children: 2.5 per 100,000 annually (home pools).

General Statistics: Between 6,000 to 8,000 drown each year in the United States.
- Drowning is the third leading cause of accidental death in the U.S.
- Second leading cause among people ages 5-44.
- About 15% of children experience near drowning by middle school.
- Most common in children under 4 years of age; over 40% of drownings occur in this group.
Circumstantial Factors: Poor adult supervision in swimming pools is the most common site of drownings.
Up to 33% of adults may experience near drowning at some point.
Near drowning victims have higher chances of survival than those who do not survive.

Age: Younger age correlates with better outcomes.
Submersion Time: The shorter, the better; approximately 60 minutes is the critical limit.
Water Temperature: Colder water (27°F to 70°F) results in better prognosis.
Water Quality: Cleaner water leads to better outcomes.
Other Injuries: None serious enhances survival chances.
Amount of Struggle: Less struggle corresponds to better survival rates.
Quality of CPR: Good technique increases survival rates.
Suicidal Intent: Lower survival rates noted among victims with suicidal attempts compared to accidental cases.

Fresh water is hypotonic to blood and is rapidly absorbed into the bloodstream, destroying pulmonary surfactant.
Results in:
- Atelectasis: Due to washed-out surfactant.
- Alveolar Consolidation: Increased thickness of the alveolar-capillary membrane.
- Bronchospasm and excessive bronchial secretions.

Increased indicators:
- Respiratory rate (tachypnea).
- Heart rate (pulse).
- Blood pressure.
- Temperature (may indicate hypothermia).
- Cyanosis can be present.

Characteristics:
- Frothy, pink, stable bubbles typical.
- Aspiration present in 85-95% of cases.
- Presence of bacteria and emesis (vomit) in aspirated fluid.

Possible sounds:
- Crackles and rhonchi.
- Wheezing indicative of bronchospasm or foreign body aspiration.

Stages: Early and advanced
- pH: Decreased
- PaCO2: Increased
- HCO3: Decreased
- PaO2: Usually decreased.
Additional Information:
- Buildup of lactate leading to decreased pH and altered enzyme function.
- May lead to cell death if oxygenation and perfusion are not restored.
- Metabolic acidosis often due to tissue hypoxia; may see reduced hemoglobin, hematocrit, and electrolyte concentrations following large volumes of fresh water aspiration (dilution effect).

Chest Radiograph Findings:
- Fluffy infiltrates indicative of pulmonary edema present.
- Acute respiratory distress syndrome (ARDS) is common in near drowning victims due to aspiration and inflammatory responses.
Example: Radiograph of young male shows typical pulmonary edema pattern post-incident (Figure 40-2).

First responder should conduct a rapid and direct assessment of Level of Consciousness (LOC):
- Check pupils, impaired sensorium, Glasgow Coma Scale (GCS).
- History should include duration of submersion, CPR attempts, alcohol use, etc.
Consider management needed during transport and upon arrival at the hospital.

Perform arterial blood gases (ABGs) to monitor ventilation and oxygenation.
Conduct chest x-ray (CXR) to assess lung conditions.
Rewarming: Important for hypothermic victims.
Intubation and Mechanical Ventilation: Required for most wet drowning victims, often with Positive End-Expiratory Pressure (PEEP) support necessary for adequate ventilation.

Surfactant:

A substance composed primarily of phospholipids and proteins that reduces surface tension in the lungs, preventing alveolar collapse and aiding in gas exchange. It plays a critical role in maintaining the stability of alveoli during breathing.
When washed out during near drowning, particularly with fresh water, pulmonary surfactant is destroyed, leading to several complications:
- Atelectasis: Collapse of portions of the lung due to the inability to keep alveoli open.
- Alveolar Consolidation: Increased thickness of the alveolar-capillary membrane, leading to impaired gas exchange.
- Bronchospasm: Constriction of the airways, further complicating breathing.
- Increased risk of pulmonary edema and acute respiratory distress syndr ome (ARDS).

PEEP (Positive End-Expiratory Pressure):

A mode of mechanical ventilation that maintains a pressure in the airways at the end of expiration to prevent alveolar collapse and improve oxygenation.
It allows for better recruitment of collapsed alveoli and improves functional residual capacity of the lungs, aiding in effective gas exchange, particularly important in cases of wet drowning where lung function is compromised.