Drowning (Pathophysiology and Management) for USMLE

Drowning Pathophysiology and Management for USMLE made simple. Handwritten lecture presentation for medical students.

Drowning is defined as submersion or immersion in liquid leading to respiratory impairment.

EPIDEMIOLOGY of DROWNING
Less than 5 years old due to neglect or decrease supervision. The 15-25 year old age group is more common in river, lakes and beaches. Risk factors are individuals who can't swim well or risky behavior, alcohol, drugs, trauma, stroke, MI and seizures while swimming.

PATHOPHYSIOLOGY OF DROWNING
Firstly , patients begin to panic and lose normal breathing pattern to maintain perfusion. Patient initially holds breath until they have air hunger due to desire to breath. Finally the drowning patient aspirates the water and there is a reflex laryngospasm and finally leads to hypoxemia.

Salt water drowning has higher osmality and higher amounts of solutes. High electrolyte concentration will draw water into alveoli from alveolar capillaries. Patients drowning in saltwater can have pulmonary edema.

Fresh Water drowning will not draw water into alveoli, rather fluid will be drawn into capillaries causing and increase in intravascular volume causing hemodilituion.

Dirty Water drowning can lead to aspiration of bacteria and eventually lead to pnuemonia. Also particulate matter can cause plugging in lungs.

Most water goes to stomach and this is important because later the water can be asiprated.

Pulmonary effects include washing out of surfactant leading to atelectasis (alveolar collapse). Since air can't entire there is subsequent V/Q mismatch and shunting. Auscultation there is wheeze crackles and shortness of breath.

Neurologic effects are caused by hypoxemia, leading to ischemia and neuronal damage. Cerebral edema may also lead to high intracranial pressure.

Cardiovascular effects of drowning are arrythmias (tachycardia/bradycardia) and atrial fibrillation. Renal effects of drowning include ATN.

MANAGEMENT OF DROWNING
Acute and prehospital stage consists of CPR, ventilation, supplemental oxygen and intubation (if apneic).

In Emergency room management of a drowning patient includes looking at Airway (intubation) and ABG PaO2 less than 60mmHg and PaCO2 greater than 50mmHg.

Breathing: Supplmental Oxygen to maintain above 94%.

For cirulation just monitor blood pressure, cardiac telemotry and check oxygen saturation and end tidal Co2.

Disabilities you need to watch for neurological symptoms by finding GCS score, elevate head to decrease intracranial pressure and consider diuretic. If seizure make sure to get non sedative and convulsant.

Exposure of drowning patients and unclothing and rewarming is important. During healing it is important to rewarm to prevent vasoconstriction which leads to diuresis and hypokalemia and hypotension.

PROGNOSIS OF DROWNING
If submersion, resusication greater than 25 minutes. Apnea, pH less than 7.1, Age greater than 14, and GCS less than 5.

This summarizes the discussion on pathophysiology and management of drowning for the USMLE