Delayed, Secondary or Dry Drowning

Last Full Review: American Red Cross Scientific Advisory Council 2015
Last Update: 2023

The existence of delayed, secondary or dry drowning has been debunked by multiple organizations. Yet, it continues to intermittently be presented to the public by the media and their consultants, spreading fear among parents who worry about the risk of letting their child participate in water-related activities and the need for long-term vigilance for deterioration following any submersion. How did these terms come into use?

 

 

 

Evidence Summary

The term “dry drowning” has been used in the past to describe drowning in which very little water was found in the lungs at autopsy, which made up about 10% of fatal drownings. This was believed to be due to reflex laryngospasm, which seals off the larynx. A review by Lunetta et al. (Lunetta, Modell and Sajantila 2004, 291) reported the actual incidence of death in persons found in the water who have normal lungs or no liquid in their airways is less than 2%, much lower than previously thought. This review and another review (Modell, Bellefleur and Davis 1999, 1119) concluded that while laryngospasm may occur during the drowning process, as the process continues, hypoxia will cause laryngeal muscles to relax and laryngospasm to resolve. Eventually, brainstem reflexes may lead to brief respiratory efforts and liquid will enter the airways and lungs. Moreover, when water enters the lungs, it is rapidly absorbed when breathing starts again. However, the amount of water that enters the lungs does not determine the amount of injury or determine the treatment of drowning. The primary clinical insult from drowning is due to the duration of anoxia (Quan et al. 2016, 63). Thus, not being able to breathe for longer than a few minutes leads to death or survival with severe end-organ damage.

A 2015 scientific review by the American Red Cross Scientific Advisory Council, which was updated in a 2023 Answer (American Red Cross Scientific Advisory Council 2023), describes how the terms “delayed,” “secondary” or “dry” drowning, as well as other misleading terms, historically developed. Until the 1980s, drowning was thought to be a problem of water in the airways, and treatment focused on removal of water believed to be in the airways. Case reports in the 1960s (prior to prehospital or emergency medical care) described delayed onset of respiratory distress in persons who initially survived drowning, but were later found dead in their hospital bed. A 1980 case series (Pearn 1980, 1103) described five pediatric patients who were initially apneic and unresponsive after a drowning event, then resuscitated and later developed respiratory symptoms. Three of these patients survived and were described as having developed post-immersion respiratory syndromes with rapid deterioration after drowning. Chin et al. (Chin, Galea and Goel 1980, 1351) described 22 children hospitalized post-drowning who developed respiratory symptoms, noting that tachypnea was the earliest presenting sign and that oxygen treatment helped and all survived.

Other case series in the 1970s described the development of acute pulmonary edema with respiratory distress in hospitalized patients. This included patients following drowning events and who had cardiac arrest or who were unconscious with respiratory arrest, and in some with mild drowning injuries who remained alert and with normal breathing immediately after rescue. The term “secondary drowning” was thus used to describe patients who survived a drowning event, but subsequently developed respiratory distress during hospitalization and acute respiratory distress syndrome (ARDS). A 2005 systematic review (Papa, Hoelle and Idris 2005, 255) of drowning studies identified multiple definitions for secondary drowning in drowning studies between 1966 and 2002, most linked to outcomes of delayed death from complications following drowning, or death soon after initial recovery.

Τhe term “secondary drowning” had no specific definition. A group consensus achieved at the Drowning Utstein Conference (Idris et al. 2003, 2565) elected to discard the term “secondary drowning,” saying that it implied a second drowning had occurred, none of which happened to any of these patients.

More recent studies evaluated the clinical course of drowning cases in a controlled environment. Noonan et al. (Noonan, Howrey and Ginsburg 1996, 368) reported that 10% of hospitalized pediatric drowning patients were asymptomatic at admission, and 70% were asymptomatic at 8 hours. Factors associated with a benign course over the next 8 hours were a normal initial exam (90% of those with normal initial exams became asymptomatic) and short submersion duration. Patients who became asymptomatic with normal oxygen saturations could be safely discharged home. An observation period of 6 to 8 hours was recommended following a drowning event.

A retrospective review in 2000 (Causey, Tilelli and Swanson 2000, 9) evaluated data from 61 patients admitted with a Glasgow Coma Scale score of 13 or higher who did not require Advanced Life Support prior to or up to 4 hours after emergency department presentation. This review reported that, by 4 to 6 hours, no patient with a normal oxygen saturation deteriorated clinically. It was suggested that patients with an oxygen saturation greater than 95% and no respiratory distress could be discharged home safely after 5 to 6 hours of observation. Patients with other significant distracting or confounding injuries and significant past medical problems (e.g., cardiac, pulmonary, neurological) were excluded from this recommendation. A case series (Milne and Cohen 2006, 775) of 22 patients seen in an emergency department reported that no one who had been truly asymptomatic following a drowning event subsequently worsened.

In summary, the evidence tells us that:

• Some patients develop worsening respiratory distress after drowning.
• Patients who develop worsening respiratory distress after drowning do so very soon after the drowning event or retrieval.
• Those who have had a drowning event leading to respiratory symptoms should be evaluated medically and be observed for 5 to 8 hours.
• Those who are asymptomatic at 5 to 8 hours after the drowning event will not develop further symptoms.
• The incidence of ARDS as presently defined is low and is usually seen in patients whose drowning led to or was associated with a cardiac arrest.

The American Red Cross Scientific Advisory Council review concludes that drowning is an event that can lead to injury to the lungs. Lung injury may progress after the event. However, there is no data to support that delayed drowning occurs in drowning persons who become asymptomatic after the event. The terms “secondary” or “delayed” drowning should not be used.

After the event, if the person has no difficulty breathing, they should be advised to be with someone for 5 to 8 hours to watch for the development of any difficulty breathing. Drowning persons should be evaluated by a healthcare professional if they:

• Are abnormal in any way after the event (e.g., brief loss of consciousness, confusion or altered mentation, intoxication, low oxygen saturation, abnormal vital signs, chest pain or persistent shortness of breath).
• Have a significant preexisting condition, especially cardiac, pulmonary or neurological.
• Have a complicated drowning event, such as with a seizure or need for rescue breathing and ventilations, chest compressions or oxygen.
• Have a distracting or significant other injury that should be evaluated by a healthcare professional.

 

Insights and Implications

Confusion about drowning terminology over the years has led to persistent misinformation. The terminology was used before drowning injuries were understood, and before prehospital care and emergency departments could evaluate breathing and ventilation abnormalities as they do now.

The medical definition of drowning is “The process of experiencing respiratory impairment from submersion or immersion in liquid” (van Beeck, et al. 2005, 853). Thus, if a person was in water and had no breathing troubles, then the person did not drown. The term “near-drowning” was once used to refer to drowning persons who survived, but it has been used in so many ways that it caused confusion. For example, consider if the word “near” was inserted before “burns” or another injury.

People who drown either die or survive (with or without morbidity, e.g., brain damage). To be clear about whether a person died or lived after a drowning event, the terms that should be used are “fatal drowning” (i.e., died) or “nonfatal drowning” (i.e., survived). Cases of rescued nonfatal drowned persons who have some mild symptoms, such as cough or confusion, are fortunately far more common than fatal drownings. For children, it is estimated that for every fatal drowning, there are five nonfatal drownings.

There are no medically accepted conditions known as near-drowning, dry drowning, secondary drowning or delayed drowning. Not restoring breathing and circulation after drowning also leads to death. Resuscitation of a person following a drowning event is the same regardless of whether water is present in the airways and lungs.

 

Drowning and Prognostic Factors

Last Full Review: ILCOR 2015
Last Update: 2020

Search-and-rescue personnel and lifeguards are at times faced with challenging environmental conditions and safety concerns when rescuing a drowning person. At times, the approach changes from a rescue to a recovery mission. Knowing what factors may predict the outcome of a drowning event can help with difficult decisions.

 

 

 

Evidence Summary

A 2015 International Liaison Committee on Resuscitation (ILCOR) systematic review (Quan et al. 2016, 63) and Consensus on Science with Treatment Recommendations (Travers et al. 2015) with an updated review in 2020 (Olasveengen 2020, S41) evaluated factors from search-and-rescue operations for adults and children submerged in water that might predict survival. Studies from the 2015 ILCOR review found that young age was not associated with favorable neurological outcome, while for the outcome of survival, results related to age were conflicting.

For the prognostic factor of emergency medical services response interval, the review found that emergency medical services response intervals of less than 10 minutes were associated with better survival (Travers et al. 2015, S51). Survival with favorable neurological outcome was positively associated with salt water in two studies, while water type was not associated with this outcome in four other studies (Olasveengen et al. 2020, S41).

For the prognostic factor of submersion duration, worse outcomes were reported for survival with favorable neurological outcome in all studies for submersion durations exceeding 5 minutes, although persons submerged for short durations compared with longer durations had good outcomes (Quan et al. 2016, 63).

For intermediate submersion intervals (i.e., less than 10 minutes), worse outcomes were reported for survival with favorable neurological outcome among persons with prolonged submersion duration compared with intermediate duration. In general, shorter submersion intervals were associated with better outcomes than longer submersion intervals (Quan et al. 2016, 63). For the prognostic factor of water temperature, two studies included in the 2015 review found no difference in survival with favorable neurological outcome with water temperature, while a second smaller study found better outcomes associated with submersion in the winter compared with submersion in spring or summer (Quan et al. 2016, 63).

For the prognostic factor of witnessed status, two studies (Nitta et al. 2013, 1568; Tobin et al. 2017, 39) reported an association of better neurological outcomes with witnessing the event (aOR, 11.8; 95% CI, 2.84–49.08, and aOR, 3.27; 95% CI, 2.0–5.36, respectively); although it was noted by the reviewers that submersion duration was not reported and several studies have reported it as an independent predictor. Four observational studies reported on survival for witnessed status with conflicting results (Olasveengen et al. 2020, S41).

 

Insights and Implications

Studies report that submersion durations of less than 10 minutes are associated with a very high chance of favorable outcome, while durations greater than 25 minutes were associated with a low chance of favorable outcome (Quan et al. 2016, 63). However, there is a lack of prospective studies to validate submersion duration as a clinical decision rule. Thus, individual case-by-case decisions must be made during rescue operations, with consideration of the risk for rescuers and the potential for benefit. Of note, the ILCOR review excluded rare and exceptional case reports of survival with good outcomes after prolonged submersion in icy cold water.