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Predicting outcome of drowning at the scene: A systematic review and meta-analyses

Article: Predicting outcome of drowning at the scene:A systematic review and meta-analyses
Authors: Quan L, Bierens J, Lis R, Rowhani-Rahbar A, Morley P, Perkins G
Journal: Resuscitation, ePub ahead of print (May 2016)

One of the toughest questions to answer in the first few hours to days following the resuscitation of a drowning patient who remains comatose is what factors associated with the patient or the event can be used to determine prognosis.  While numerous studies have been done in the past to help answer this question, most are plagued by low quality data or designs and a focus on overall mortality instead of neurologic outcome. In this systematic review and meta-analysis, the authors focused on scene factors which could possibly help determine prognosis.

Summary

Study Type: Systematic review and meta-analysis

Period: 1979-2015

Inclusion: Cohort and case-control studies reporting:

• Submersion duration 
• Age
• Water temperature
• Salinity
• EMS response time
• Survival and/or neurological outcome

Results

• 24 cohort studies
• Submersion duration strongest predictor
• ≤ 10 min predicted high rate of good outcome
•  ≥ 25 min associated with dismal outcome
• Factors not showing prognostic value
• Age
• Water temperature
• Factors showing some prognostic value
• Salinity: salt water favorable
• EMS response time: the shorter, the better
• Both factors had very weak prognostic value

The most important conclusion of this paper, and one made many times before, is that the longer a person is submerged underwater, the worse chance they have for good neurologic outcome.  While there is no obvious cut-off time, and large variability, this analysis was able to produce a dose-response curve showing a correlation between submersion time and outcome. This time is a marker of anoxic brain injury.  The cut-offs of 10 min and 25 min were used to differentiate between strong chances of good outcome and bad outcome, respectively, but times in between are in a gray zone of uncertainty. An important note is that all of the papers analyzed were judge to have a low or very low level of evidence.

Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Drowning

We are very excited to announce the open-access publication of our recent practice guidelines developed for the Wilderness Medial Society. They cover the treatment of drowning, primarily in the austere and wilderness environment, including information to help guide the rural Emergency Medicine physician.

Click Here for link to article

Ref:

Schmidt AC, Sempsrott JR, Hawkins SC, Arastu AS, Cushing TA, Auerbach PS.
Wilderness Medical Society Practice Guidelines for the Prevention and Treatment
of Drowning. Wilderness Environ Med. 2016 Apr 6.

Extracorporeal life support for victims of drowning

Title: Extracorporeal life support for victims of drowning
Authors: Burke CR, et al
Journal: Resuscitation, April 10, 2016 [epub ahead of publication]

This article analyses a subset of patients from the Extracorporeal Life Support (ELSO) international registry, which collects data from patients undergoing extracorporeal life support (ECLS) from over 400 international centers. Data for drowning patients from 1986 to 2015 were queried from the registry.

Primary outcome: survival to hospital discharge or transfer
Patients: 247 total (49 adults, 198 pediatrics)

• 35% had cardiac arrest with ROSC prior to ECLS (Arrest group)
• 31% ad ECLS initiated during cardiac arrest (ECPR group)
• 34% did not have cardiac arrest before or during ECLS (No Arrest group)

Results

• Overall survival 51%
• No Arrest: 74%
• Arrest: 57%
• ECPR: 23%
  
• Younger patients more likely to be "No Arrest"
  
• Non-survivors
• more likely to be "Arrest" than survivors
• No difference in age, sex, race
• Presented with lower pH, lower SaO2, and more hypothermia

Discussion

Unfortunately, this article does not answer any of the big questions in drowning resuscitation, primarily "who is walking out of the hospital with good neurologic outcome".  The authors acknowledge this weakness, but it is somewhat beyond their control as the registry itself is limited and primarily focused on ECLS itself and not specific diseases/injuries leading to ECLS.  I do like the use of an international registry to gather a wide-array of data across multiple institutions, but what is needed next is a method to match this data with more robust pre-hospital and hospital data and, most importantly, neurologic outcome data.  To data, the question as to whether ECLS is beneficial in drowning patients has yet to be answered, but registries like this may make it possible one day.  The conclusions gained from this article are in line with previous evidence: Those who experience cardiac arrest do worse, pediatrics tend to do better, and those who are severely acidotic, hypoxic, or hypothermic on arrival do worse.

Reference

Burke CR, Chan T, Brogan TV, Lequier L, Thiagarajan RR, Rycus PT, MichaelMcMullan D. Extracorporeal life support for victims of drowning. Resuscitation.2016 Apr 20;104:19-23. doi: 10.1016/j.resuscitation.2016.04.005. [Epub ahead ofprint]