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01Pathophysiology

Drowning is defined by the WHO (2002 World Congress on Drowning) as the process of experiencing respiratory impairment from submersion or immersion in liquid. This definition does not require death; the outcome can range from no injury to fatal. The terms "near-drowning," "dry drowning," "secondary drowning," and "wet drowning" are outdated and are no longer recommended in clinical or examination language.

The pathophysiology begins when a victim is submerged and can no longer maintain a patent airway above water. The initial response is voluntary breath-holding, followed by involuntary swallowing of water and then laryngospasm triggered by water contacting the posterior pharynx and the larynx. Laryngospasm is a protective reflex but it creates a complete airway obstruction. The victim cannot inhale or exhale, leading to progressive hypoxia and hypercapnia. Eventually, as the brain becomes more hypoxic, the laryngospasm relaxes, and water is aspirated into the lungs.

Aspirated water damages the alveoli through two mechanisms depending on the type of water:

Freshwater drowning (hypotonic relative to plasma): Freshwater rapidly crosses the alveolar-capillary membrane into the pulmonary vasculature due to the osmotic gradient. This causes destruction and inactivation of surfactant, leading to alveolar collapse (atelectasis), ventilation-perfusion ($V\mathrm{/}QV/Q$) mismatch, and intrapulmonary shunting. If large volumes are aspirated (>22 mL/kg, which is uncommon in survivors), hemodilution can cause hyponatremia, hypervolemia, and even hemolysis with resultant hyperkalemia.

Saltwater drowning (hypertonic, roughly 3% NaCl): Saltwater draws plasma fluid into the alveolar space through the osmotic gradient, causing surfactant washout and protein-rich fluid exudation into the alveoli. This produces rapid and severe noncardiogenic pulmonary edema. The patient becomes hypovolemic relative to freshwater drowning, and serum sodium may rise.

In clinical practice, the distinction between freshwater and saltwater aspiration is largely academic for the living patient. Both mechanisms converge on the same final common pathway: surfactant dysfunction, alveolar collapse, $V\mathrm{/}QV/Q$ mismatch, intrapulmonary shunting, and severe hypoxemia. This drives the development of acute respiratory distress syndrome (ARDS) and noncardiogenic pulmonary edema. Clinically relevant electrolyte abnormalities are rarely seen in patients who survive to hospital presentation, because the volume of aspirated water in survivors is typically only 1-4 mL/kg.

The primary injury in drowning is hypoxia. Cerebral hypoxia is the main determinant of long-term morbidity and mortality. As hypoxia progresses, the heart responds with bradycardia and eventually pulseless electrical activity (PEA) or asystole. Unlike a primary cardiac event, drowning-induced cardiac arrest is the end-result of respiratory failure. This is why the resuscitation strategy must prioritize ventilation and oxygenation over defibrillation.

Hypothermia frequently complicates drowning. Cold water immersion lowers core body temperature, which can cause cardiac arrhythmias (including ventricular fibrillation). However, hypothermia also has a neuroprotective effect by reducing cerebral metabolic demand. The mammalian diving reflex, triggered by cold water contacting the face (via the ophthalmic division of the trigeminal nerve), produces apnea, bradycardia, and peripheral vasoconstriction, shunting blood to the brain and heart. This is why children submerged in cold water may sometimes have better neurological outcomes than expected, and it is the basis for the clinical principle: "No one is dead until they are warm and dead."

02Classification: Clinical Severity

The Szpilman Classification (1997, revalidated in subsequent studies) is the most widely used drowning severity grading system. It stratifies patients based on cardiopulmonary status at the scene and predicts mortality.

A Rescue (grade 0) is when the patient is removed from water with no respiratory symptoms. The distinction between Rescue and Grade 1 is the presence of coughing. This is a testable detail.

The updated reappraisal data (2020) from Boulain et al. showed that with rapid extraction (<10 minutes) and early specialized care, mortality for Grades 2-5 has improved substantially (0-3%), while Grade 6 (cardiac arrest) remains the prognostic cornerstone with mortality around 54%. This confirms that submersion duration and time to CPR are the two most important prognostic variables.

03Diagnostic Workup

The best initial test at the bedside is pulse oximetry combined with clinical assessment (auscultation, level of consciousness, and presence of respiratory distress). This is what you use to grade severity using the Szpilman classification.

The first laboratory test to order is an ABG. It provides three essential data points simultaneously: the degree of hypoxemia ($Pa{O}_{2}PaO\_2$), the ventilatory status ($PaC{O}_{2}PaCO\_2$), and the metabolic status (pH and $HC{O}_3^{-}HCO\_3^-$). You can also calculate the $A-agradientA-a\backslash \; gradient$, which will be elevated due to intrapulmonary shunting from surfactant dysfunction and alveolar flooding. The formula is:

$$A\text{-}agradient=[Fi{O}_2\times (P_{atm}-P_{H_{2}O})]-\frac{PaC{O}_2}{0.8}-Pa{O}_{2}A\backslash text\{-\}a\backslash \; gradient\; =\; [FiO\_2\; \backslash times\; (P\_\{atm\}\; -\; P\_\{H\_2O\})]\; -\; \backslash frac\{PaCO\_2\}\{0.8\}\; -\; PaO\_2$$

A CXR should be obtained, but you must understand that a normal initial CXR does not rule out significant aspiration. Radiographic findings may be delayed by 4 to 6 hours after the event. This is a frequently tested concept. Patients with a normal CXR on arrival who are symptomatic (coughing, tachypnea, abnormal auscultation) still require observation.

An ECG is essential to evaluate for arrhythmias and to look for signs of hypothermia. The Osborn wave (J wave) is a positive deflection at the J-point (junction of the QRS and ST segment) and is a classic ECG finding in hypothermia. It does not require treatment beyond rewarming.

Laboratory electrolytes are checked to screen for derangements, but as noted, clinically relevant changes are uncommon in survivors. If the patient has altered mental status that does not improve after correction of hypoxia and rewarming, a CT head should be obtained to assess for hypoxic-ischemic brain injury.

The most important prognostic factors are submersion time >5 minutes, delay in CPR >10 minutes, GCS of 3 on arrival, fixed dilated pupils, pH <7.00, and persistent coma at 24-48 hours.

04Management & Treatment

Management by Szpilman Grade

Prehospital and Resuscitation Principles

The 2024 AHA/AAP Focused Update on Resuscitation Following Drowning contains several high-yield principles that differ from standard cardiac arrest management:

Ventilation-first approach. Because drowning-induced cardiac arrest originates from respiratory failure and hypoxia, the resuscitation sequence should prioritize airway and ventilation. For healthcare providers, the recommended sequence is A-B-C (Airway, Breathing, Compressions), not C-A-B as in primary cardiac arrest. The rationale is that the heart stopped because the patient could not breathe; restoring oxygenation is therefore the primary intervention.

CPR with rescue breaths, not compression-only CPR. Compression-only CPR is less effective in drowning because it does not address the underlying hypoxia. The 2024 guidelines recommend that CPR with rescue breaths (conventional CPR) should be performed for all drowning victims in cardiac arrest. However, if the rescuer is untrained, unwilling, or unable to provide rescue breaths, compression-only CPR is still preferable to no CPR at all.

In-water rescue breathing. Trained rescuers may begin rescue breathing while still in the water if it can be done safely. Chest compressions require a firm surface and cannot be effectively delivered in water. Once on land or a firm surface, full CPR begins.

AED use. An AED should be applied once the patient is out of the water and the chest is dried. However, most drowning-related cardiac arrests present with non-shockable rhythms (PEA or asystole), so the AED will often advise "no shock." Early ventilation and oxygenation provide a greater survival advantage than immediate defibrillation in drowning.

Do NOT attempt abdominal thrusts (Heimlich maneuver). This is a classic exam trap. Abdominal thrusts do not clear water from the lungs and only increase the risk of vomiting and aspiration. The Heimlich maneuver is indicated for foreign body airway obstruction, not for drowning.

In-Hospital Management

Oxygenation and ventilation are the cornerstone. If the patient requires intubation and mechanical ventilation, use a lung-protective ventilation strategy identical to ARDS management: low tidal volume (6-8 mL/kg ideal body weight), PEEP titrated to oxygenation, and plateau pressure <30 cmH2O. PEEP is beneficial because it recruits collapsed alveoli and counteracts the surfactant dysfunction.

Hypothermia management. If core temperature is below 35 degrees Celsius, active rewarming is needed. For mild hypothermia (32-35 degrees Celsius), passive external rewarming (blankets, warm environment) and active external rewarming (forced warm air blankets such as Bair Hugger) are sufficient. For severe hypothermia (<30 degrees Celsius), active core rewarming may be required: warm IV fluids (38-42 degrees Celsius), warm humidified oxygen, and in extreme cases, peritoneal lavage, pleural lavage, or extracorporeal membrane oxygenation (ECMO). CPR should continue in hypothermic patients until core temperature reaches at least 32-35 degrees Celsius before declaring death.

No role for prophylactic antibiotics. Antibiotics are only indicated if the patient develops clinical signs of infection (fever, purulent secretions, new infiltrates after initial improvement). Aspiration pneumonia from contaminated water (rivers, ponds, sewage) is more likely to involve gram-negative organisms and atypical pathogens; tailor antibiotics when culture data is available.

No role for corticosteroids. There is no evidence that systemic steroids improve outcomes in drowning-associated ARDS.

No role for routine cervical spine immobilization unless there is a clear mechanism for spinal injury (diving into shallow water, boating accident, or visible head/neck trauma). A blanket application of spinal precautions to all drowning patients delays resuscitation without evidence of benefit.

Observation and Disposition

Asymptomatic patients (Szpilman Grade 1 or Rescue) should be observed for 4-6 hours in the emergency department. If they remain symptom-free with normal pulse oximetry and a normal or stable CXR, they can be discharged safely. The historical fear of delayed respiratory deterioration ("secondary drowning") is not supported by evidence; symptomatic deterioration after a truly asymptomatic observation period is exceedingly rare.

05Indonesian Context

Emergency Numbers and Rescue Services

In Indonesia, the emergency numbers for ambulance and medical emergencies are 118 or 119. For search and rescue operations (BASARNAS), the number is 115. The natural disaster assistance line is 129. The number 112 is being rolled out as a unified national emergency number. Coverage is best in Java and Bali, while the traditional numbers (110, 118, 113, 115) remain active throughout the country.

For drowning incidents in water bodies, coastal areas, or during natural disasters, BASARNAS (Badan SAR Nasional) at 115 is the appropriate agency for active water rescue operations.

Epidemiological Burden

Between 2005 and 2019, Indonesia consistently had high drowning mortality in children under 5 years of age, averaging 9.7 deaths per 100,000 annually, which exceeds the global rate of 5.5 per 100,000. Children in eastern Indonesia (Papua, Maluku, and Nusa Tenggara) recorded the highest fatalities. Children under 5 were 3.67 times more likely to fatally drown than individuals aged 15-49, with particularly high risks in Papua, Kalimantan, Sulawesi, Maluku, and Nusa Tenggara regions.

Regulatory Framework

Indonesia's disaster management is led by the Badan Nasional Penanggulangan Bencana (BNPB), established in 2008 under Presidential authority. The legal foundation is UU No. 24 Tahun 2007 (Law Number 24 of 2007) on Disaster Management (Penanggulangan Bencana), which provides the framework for prevention, mitigation, preparedness, emergency response, and recovery across all types of disasters, including hydrometeorological events such as floods and tsunamis where drowning is a primary cause of death.

The Indonesian National Disaster Management Agency recorded from 1815 to 2023: 13,927 flooding events with 22,476 deaths and 8,195 missing; 9,503 flooding and avalanche events with 3,324 deaths; and 11,225 cyclone events with 479 deaths.

Indonesia does not have a standalone national law dedicated solely to drowning prevention. Instead, drowning prevention falls under the broader disaster management framework (BNPB) and the Ministry of Health's emergency care protocols (Sistem Penanggulangan Gawat Darurat Terpadu / SPGDT). Indonesian literature emphasizes that the high drowning death rate is partly due to inadequate knowledge of initial treatment among the public and limited understanding of emergency procedures. Indonesian clinical references confirm that the key to drowning management is performing basic CPR so the patient regains consciousness and resumes breathing, and mouth-to-mouth respiration can be initiated while extracting the patient from the water.

06Differential Diagnosis & Distractors

07Traps & High-Yield Pearls

The most common way students get drowning questions wrong is by applying standard cardiac arrest resuscitation logic to a drowning victim. In a primary cardiac arrest (e.g., from ventricular fibrillation due to an MI), the sequence is C-A-B and defibrillation takes priority. In drowning, the heart stopped because the lungs failed first. Therefore, the correct answer for the first step in management of a pulseless drowning victim is rescue breathing and ventilation (A-B-C), not chest compressions first and not "apply AED immediately." Most drowning victims arrest in a non-shockable rhythm (PEA/asystole), so the AED will not deliver a shock.

The second major trap is the Heimlich maneuver (abdominal thrusts). Students who remember "water in the lungs" may incorrectly choose the Heimlich to "expel the water." This is wrong. Abdominal thrusts are only for solid foreign body obstruction. In drowning, the Heimlich increases gastric regurgitation and worsens aspiration risk. If you see an answer choice offering the Heimlich maneuver for a drowning victim, it is a distractor.

The third trap involves the normal initial CXR. A vignette may describe a child pulled from a pool who is coughing and tachypneic, then show you a normal CXR and ask the next step. The wrong answer is "discharge home." The correct answer is observation for 4-6 hours with repeat assessment. CXR changes from pulmonary edema can be delayed.

The fourth trap involves freshwater versus saltwater distinction. If a question asks you to differentiate management based on whether the patient drowned in freshwater or saltwater, the answer is almost always "management does not differ." Both lead to surfactant dysfunction, ARDS, and hypoxia. The electrolyte distinctions are of forensic or pathological interest, not clinical management significance.

The fifth pearl concerns hypothermia and resuscitation duration. In hypothermic drowning patients, resuscitation should be continued until the patient's core temperature is rewarmed to at least 32-35 degrees Celsius. A hypothermic patient in cardiac arrest may appear clinically dead but may still be salvageable. This is the logic behind "nobody is dead until warm and dead." If a question presents a cold-water drowning victim with fixed dilated pupils and asystole and asks whether to continue CPR, the answer is yes, continue CPR and rewarm.

Finally, remember that prophylactic antibiotics and corticosteroids have no role in drowning management. If a question asks what to prescribe prophylactically to a drowning victim, the correct answer is neither. Antibiotics are given only when infection is clinically evident.

The core competency being tested in drowning questions is your ability to recognize that drowning is fundamentally a respiratory emergency, to sequence your resuscitation accordingly (ventilation first), to avoid common procedural traps (Heimlich, compression-only CPR, early AED prioritization), and to understand the observation period for the initially well-appearing patient.