What causes the feeling of drowning?

From the Guidelines

The feeling of drowning is primarily caused by the inability to breathe due to laryngospasm triggered by water entering the airways, leading to oxygen deprivation, rising carbon dioxide levels, and panic signals from the brain. This process begins when the victim's airway lies below the surface of the liquid, usually water, at which time the victim voluntarily holds his or her breath, followed by an involuntary period of laryngospasm secondary to the presence of liquid in the oropharynx or larynx 1. As the victim's arterial oxygen tension drops further, laryngospasm abates, and the victim actively breathes liquid, resulting in changes in the lungs, body fluids, blood-gas tensions, acid-base balance, and electrolyte concentrations 1.

The recent guidelines from the American Heart Association and American Academy of Pediatrics support the idea that hypoxia is the major sequela of drowning, and optimizing oxygenation is crucial in resuscitation efforts 1. The use of maximal available oxygen concentration during CPR is recommended, highlighting the importance of addressing oxygen deprivation in drowning cases 1.

Key factors contributing to the feeling of drowning include:

• Laryngospasm triggered by water entering the airways
• Oxygen deprivation and rising carbon dioxide levels
• Panic and distress signals from the brain
• Disruption of normal gas exchange process and damage to lung tissue if water enters the lungs
• Inflammation and fluid buildup in the lungs over time in secondary drowning cases

The most recent and highest quality study, the 2024 American Heart Association and American Academy of Pediatrics focused update, emphasizes the importance of optimizing oxygenation in drowning resuscitation efforts 1. This study provides the most up-to-date guidance on addressing the feeling of drowning and its underlying physiological responses.

From the Research

Physiological Response to Drowning

• The feeling of drowning is caused by the process of experiencing respiratory impairment from submersion or immersion in liquid 2.
• When water is aspirated into the airways, coughing is the initial reflex response, followed by acute lung injury that alters the exchange of oxygen in different proportions 2.
• The combined effects of fluid in the lungs, loss of surfactant, and increased capillary-alveolar permeability result in decreased lung compliance, increased right-to-left shunting in the lungs, atelectasis, and alveolitis, a noncardiogenic pulmonary edema 2.

Medical Conditions and Drowning

• Pre-existing medical conditions, such as ischemic heart disease and seizure disorders, can increase the risk of fatal drowning 3.
• Fatal drowning occurred more frequently in people with ischemic heart disease (RR 2.7) and seizure disorders (RR 6.3), but less frequently in people with respiratory disease (RR 0.12) 3.
• The risk of fatal drowning is also increased in people with certain medical conditions, such as COPD, which can modify the initial presentation of venous thromboembolism (VTE) and worsen the short-term prognosis of patients who have acute pulmonary embolism (PE) 4.

Relationship between COPD and Cardiovascular Events

• COPD is strongly associated with cardiovascular disease, in particular acute myocardial infarction (AMI) 5.
• The prevalence of COPD amongst AMI populations ranges from 7% to 30%, and patients with COPD have an increased risk of mortality, heart failure, and arrhythmias during follow-up 5.
• Acute exacerbations (AEs) of COPD are increasingly recognized as episodes of heightened risk of cardiovascular events, including myocardial infarction (MI) and pulmonary embolism (PE) 6.
• The number and severity of AEs of COPD are associated with increased long-term risk of both MI and PE in a gradual fashion 6.