Study Notes on Near Drowning

Chapter 42: Near Drowning

Near Drowning Definition

  • Near Drowning: Refers to a situation where the victim survives submersion in a liquid at least temporarily.

  • A situation is generally considered a "near drowning" when victims are successfully resuscitated and survive at least 24 hours post-incident.

Types of Drowning

Dry Drowning

  • Statistics: 10-15% of drowning victims do not aspirate fluid into their lungs.

  • Definition: Dry drowning refers to death occurring without the aspiration of water, primarily due to acute asphyxia.

  • Mechanism:

    • Resulting conditions include laryngospasm or prolonged breath-holding.

    • The glottis spasms, which prevents water from entering the lungs.

Wet Drowning

  • Definition: Wet drowning occurs when death results from suffocation due to submersion.

  • Statistics: 85-90% of drowning victims are characterized as experiencing wet drowning due to aspiration of liquid.

  • Fluid Ingestion: Typically, less than 22 ml/kg of fluid is aspirated.

  • Mechanism:

    • In contrast to dry drowning, the glottis relaxes, allowing fluid entry into the lungs.

Physiological Changes Following Near Drowning

  • Pulmonary Response:

    • Fluid inhalation causes bronchial walls to constrict.

    • Activation of the parasympathetic reflex is observed.

    • Non-cardiogenic pulmonary edema develops as fluid moves from pulmonary capillaries into bronchioles and alveoli.

    • Alveolar walls and interstitial spaces become engorged or swollen.

    • Surfactant levels decrease, resulting in increased surface tension in the alveoli.

  • Associated Pathophysiological Changes:

    • Laryngospasm, interstitial edema (including engorgement of perivascular and peribronchial spaces), and decreased pulmonary surfactant.

    • Increased surface tension of alveolar fluid leads to frothy, white, and pink secretions throughout the tracheobronchial tree.

    • Alveolar shrinkage and atelectasis followed by alveolar consolidation, and potential bronchospasm can occur.

Etiology and Epidemiology

  • General Statistics:

    • Approximately 6000 to 8000 people drown each year in the United States.

    • Drowning ranks as the third leading cause of accidental death in the U.S.

    • It is the second leading cause of accidental death among individuals between the ages of 5 and 44.

    • About 15% of children experience near drowning incidents by middle-school age.

    • The greatest incidence occurs in teenagers and children under 4 years old, with more than 40% of drownings in that age group.

  • Demographic Factors:

    • 50% of adult drowning victims are reported to have consumed alcohol prior to the incident.

    • Gender analysis shows nearly 80% of drowning victims are male.

    • Drowning rates in African-American children: 4.5 per 100,000 annually, often in freshwater lakes and ponds.

    • Caucasian children drown at a rate of 2.5 per 100,000 annually, typically in home swimming pools.

    • Swimming pools lacking adequate adult supervision are reported as common drowning sites.

    • Up to 33% of adults may have experienced near drowning at some point.

    • Victims of near drowning are observed to have the highest chances of survival.

Sequence of Drowning or Near Drowning

  • Sequence:

    1. Panic and violent struggle to return to the surface.

    2. Period of calmness followed by apnea.

    3. Swallowing of large amounts of fluid, leading to vomiting.

    4. Gasping inspirations and resulting aspiration.

    5. Convulsions.

    6. Coma.

    7. Death.

Favorable Prognostic Factors in Cold-Water Near Drowning

  • Age: Younger individuals tend to have a better prognosis.

  • Submersion Duration: Shorter duration is preferable (60 minutes is the upper limit for cold-water submersions).

  • Water Temperature: Colder temperatures improve survival chances (optimal range is from 27°F to 70°F).

  • Water Quality: Cleaner water results in better outcomes.

  • Presence of Other Injuries: The absence of serious additional injuries is favorable.

  • Amount of Struggle: Less struggle corresponds with better prognostic factors.

  • CPR Quality: Effective cardiopulmonary resuscitation (CPR) improves survival rates.

  • Suicidal Intent: Lower rates of survival are seen in individuals who attempted suicide compared to accidental submersion victims.

Clinical Manifestations of Near Wet Drowning

  • Mechanisms Causing Clinical Manifestations:

    • Freshwater aspired in cases is hypotonic relative to blood, rapidly absorbed into the bloodstream.

    • It destroys pulmonary surfactant, leading to atelectasis (washout of surfactant).

    • Consolidation of alveoli and increased alveolar-capillary membrane thickness.

    • Resulting bronchospasm and excessive bronchial secretions.

Physical Examination of Drowning Victims

Vital Signs Assessment

  • Increased:

    • Respiratory rate (tachypnea).

    • Heart rate (pulse).

    • Blood pressure.

    • Temperature indicating hypothermia.

  • Cyanosis: Observed in victims due to lack of oxygen.

Cough and Sputum Production

  • Frothy, pink stable bubbles are often found.

  • Aspiration occurs in 85-95% of cases.

  • Bacteria and vomitus may be present in aspirated material.

Chest Assessment Findings

  • Listening to the lungs may reveal:

    • Crackles and rhonchi.

    • Wheezes, particularly if bronchospasm or foreign body aspiration is present.

Clinical Data and Laboratory Tests

Arterial Blood Gases (ABGs) in Near Drowning

  • Early and Advanced Stages:

    • pH decreases, indicating acidosis.

    • PaCO2 levels increase.

    • HCO3 levels decrease.

    • PaO2 decreases.

  • Causative Mechanisms:

    • Accumulation of lactate leads to decreased pH, altering enzyme function and potentially resulting in cell death if oxygenation and perfusion are not restored.

    • Metabolic acidosis can arise, typically linked to tissue hypoxia.

    • Aspirated freshwater may cause dilution in hemoglobin, hematocrit, and electrolyte concentrations.

Radiologic Findings

  • Chest Radiograph:

  • May show fluffy infiltrates, which indicate the presence of pulmonary edema.

  • Acute Respiratory Distress Syndrome (ARDS) is frequently seen in near drowning victims due to aspiration and inflammatory responses.

Management of Near Wet Drowning

Field Management by First Responders

  • Conduct a rapid and direct assessment of the level of consciousness (LOC), focusing on pupils, sensorium impairment, and Glasgow Coma Scale (GCS) ratings.

  • Include patient history, especially the duration of time submerged, and factors such as CPR, use of alcohol, and diving activities.

Hospital Management

  • Recommended actions include:

    • Initial ABG analyses for monitoring ventilation and oxygenation.

    • Chest X-Ray (CXR) examination.

    • Rewarming the patient as needed.

    • Consider intubation and mechanical ventilation with Positive End-Expiratory Pressure (PEEP), as support is required for most wet drowning victims.

Positive End-Expiratory Pressure (PEEP) is a form of mechanical ventilation support used for patients who have experienced wet drowning. It is designed to keep the alveoli open at the end of expiration to improve oxygenation and reduce the risk of atelectasis by preventing the collapse of alveolar units, thereby enhancing gas exchange.

Surfactant is a substance composed of lipids and proteins that reduces surface tension in the alveoli, allowing for easier expansion during inhalation and preventing collapse during exhalation. It plays a critical role in maintaining proper lung function and gas exchange. In cases of near drowning, surfactant levels may decrease due to fluid aspiration, leading to increased surface tension and complications such as atelectasis.