The Emergency Call on Drowning

Official title

The Emergency Call on Drowning: A Registry-based Cohort Study of the Characteristics, Predictors, and Outcomes of Fatal and Non-fatal Drowning

Overview

This study aims to 1) describe patient-, setting-, and dispatcher-related characteristics in drowning-related emergency calls to the Emergency Medical Dispatch Centre (1-1-2 emergency phone) and 2) factors associated with 30-day survival. The investigators will separately analyse drowning-related out-of-hospital cardiac arrest (OHCA) and drowning-related non-OHCA. If feasible, the investigators will qualitatively analyse the calls to identify and describe potential barriers for an optimal handling strategy.

Detailed description

Previous studies have explored emergency priority levels, emergency call categorisations, barriers to assessing an emergency call, and the effects on the outcome. However, this has never been done specifically for drowning patients. Drowning presents a rare and special circumstance that may be particularly complex for laypeople and medical dispatchers for several reasons. Despite this complexity and medical dispatchers' potential to optimize treatment and improve outcomes in drowning incidents, the characteristics of drowning-related emergency calls have never been explored.

This protocol presents a registry-based cohort study of drowning-related emergency medical calls to the EMDC (1-1-2 emergency phone) with 30-day follow-up.

Data from the national Danish Prehospital Drowning Data will be linked with audio files and electronic data from the EMDC database using the patient's unique civil registration numbers.

The investigators will construct two lists of variables: one list for OHCA and one for non-OHCA emergency calls. Data collection from the EMDC database will consist of three phases.

In phase 1, three independent reviewers will listen to 20 emergency calls on drowning (10 OHCA and 10 non-OHCA) to identify relevant variables from the calls (e.g., presence of key symptoms \[since an emergency call often does not contain information regarding the absence of symptoms\], communication barriers \[anything that comes in the way of receiving and understanding information\], pre-arrival instructions to callers etc.).

In phase 2, the same reviewers will listen to 20 other emergency calls (10 OHCA and 10 non-OHCA) and use the lists for data collection to determine the data availability and completeness. This may result in modifications to the lists of variables. The investigators will use the results as a basis for reviewer training and calculate inter-rater reliability.

Once the reviewers' performances are satisfying (defined as Fleiss kappa ≥0.8), the investigators will move to phase 3 and collect data for all the drowning calls. Emergency calls will be stratified as OHCA or non-OHCA calls.

Interventions

• Other Drowning-related OHCA
  These patients were involved in a drowning incident (submersion or immersion in liquid) and experienced out-of-hospital cardiac arrest (OHCA), defined as being unconscious and not breathing normally at any time in the prehospital setting. Some of these patients may die as a consequence of the submersion injury (fatal drowning), while others may survive (non-fatal drowning).
• Other Drowning-related non-OHCA
  These patients were involved in a drowning incident (submersion or immersion in liquid) but did not experience an OHCA. Some of these patients may die as a consequence of the submersion injury (fatal drowning), while others may survive (non-fatal drowning).

Primary outcome measures

• Patient-related characteristics influencing the 30-day survival [Time frame: 30 days after the drowning incident]
• Setting-related characteristics influencing the 30-day survival [Time frame: 30 days after the drowning incident]
• Caller-related characteristics influencing the 30-day survival [Time frame: 30 days after the drowning incident]
• Dispatcher-related characteristics influencing the 30-day survival [Time frame: 30 days after the drowning incident]

Eligibility criteria

Inclusion criteria

• Patients at all ages registered in the Danish Prehospital Drowning Data are eligible.

Exclusion criteria

• Obvious clinical signs of irreversible death (decapitation, decomposition, post-mortem lividity, post-mortem rigidity)
• A valid Do-Not-Attempt-Resuscitation (DNAR) order or other code status orders limiting life-sustaining therapies
• Missing or corrupted audio files
• Missing identification number
• Missing 30-day survival

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Cohort

Study locations

Denmark · 1 center

• Prehospital Center Region Zealand — Næstved

Publications

• Breindahl N, Wolthers SA, Jensen TW, Holgersen MG, Blomberg SNF, Steinmetz J, Christensen HC; Danish Cardiac Arrest Group. Danish Drowning Formula for identification of out-of-hospital cardiac arrest from drowning. Am J Emerg Med. 2023 Nov;73:55-62. doi: 10.1016/j.ajem.2023.08.024. Epub 2023 Aug 15. PMID 37619443
• Breindahl N, Wolthers SA, Moller TP, Blomberg SNF, Steinmetz J, Christensen HC; Danish Drowning Validation Group. Characteristics and critical care interventions in drowning patients treated by the Danish Air Ambulance from 2016 to 2021: a nationwide registry-based study with 30-day follow-up. Scand J Trauma Resusc Emerg Med. 2024 Mar 6;32(1):17. doi: 10.1186/s13049-024-01189-y. PMID 38448994

Identifiers

NCT: NCT06310486 · DROWN_CALL

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗