Danish Drowning Formula for identification of out-of-hospital cardiac arrest from drowning

The role of accidental hypothermia in drowning patients with out-of-hospital cardiac arrest: A nationwide registry-based cohort study

AIM

This study aimed to investigate the associations between hypothermia and mortality or poor neurological outcome in a nationwide cohort of drowning patients with out-of-hospital cardiac arrest (OHCA).

METHODS

This nationwide, registry-based cohort study reported in-hospital data on drowning patients with OHCA following the Utstein Style For Drowning. Drowning patients with OHCA were identified in the Danish Cardiac Arrest Registry from 2016 to 2021. The primary outcome was the rate of mortality or poor neurological outcome (corresponding to a modified Rankin Scale [mRS] score > 3) at 180 days after the drowning incident in patients with OHCA and accidental hypothermia (<35 °C) vs normothermia (≥35 °C).

RESULTS

This study identified 118 drowning patients with OHCA and found an increased rate of mRS > 3 at 180 days after the drowning incident in the hypothermic group compared to the normothermic group (74% vs 18%, p < 0.001). The 180-day mortality (mRS = 6) was 69% in the hypothermic group compared to 16% in the normothermic group (p < 0.001). The hypothermic group had higher rates of ongoing CPR at hospital admission (45% vs 7%, p < 0.001), intensive care unit admission (70% vs 41%, p = 0.003), and mechanical ventilation during hospitalisation (78% vs 32%, p < 0.001) compared to the normothermic group.

CONCLUSION

Hypothermic drowning patients with OHCA had a higher risk of mortality or poor neurological outcome at 180 days compared to normothermic drowning patients with OHCA. This association may likely be explained by confounding factors such as prolonged submersion and cardiac arrest. Further research is warranted.

The Danish Drowning Cohort: Utstein-style data from fatal and non-fatal drowning incidents in Denmark

BACKGROUND

Effective interventions to reduce drowning incidents require accurate and reliable data for scientific analysis. However, the lack of high-quality evidence and the variability in drowning terminology, definitions, and outcomes present significant challenges in assessing studies to inform drowning guidelines. Many drowning reports use inappropriate classifications for drowning incidents, which significantly contributes to the underreporting of drowning. In particular, non-fatal drowning incidents are underreported because many countries do not routinely collect this data.

THE DANISH DROWNING COHORT

The Danish Drowning Cohort was established in 2016 to facilitate research to improve preventative, rescue, and treatment interventions to reduce the incidence, mortality, and morbidity of drowning. The Danish Drowning Cohort contains nationwide data on all fatal and non-fatal drowning incidents treated by the Danish Emergency Medical Services. Data are extracted from the Danish prehospital electronic medical record using a text-search algorithm (Danish Drowning Formula) and a manual validation process. The WHO definition of drowning, supported by the clarification statement for non-fatal drowning, is used as the case definition to identify drowning. All drowning patients are included, including unwitnessed incidents, non-conveyed patients, patients declared dead prehospital, or patients with obvious clinical signs of irreversible death. This method allows syndromic surveillance and monitors a nationwide cohort of fatal and non-fatal drowning incidents in near-real time to inform future prevention strategies. The Danish Drowning Cohort complies with the Utstein style for drowning reporting guidelines. The 30-day mortality is obtained through the Civil Personal Register to differentiate between fatal and non-fatal drowning incidents. In addition to prehospital data, new data linkages with other Danish registries via the patient's civil registration number will enable the examination of various additional factors associated with drowning risk.

CONCLUSION

The Danish Drowning Cohort contains nationwide prehospital data on all fatal and non-fatal drowning incidents treated by the Danish Emergency Medical Service. It is a basis for all research on drowning in Denmark and may improve preventative, rescue, and treatment interventions to reduce the incidence, mortality, and morbidity of drowning.

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

BACKGROUND

Improving oxygenation and ventilation in drowning patients early in the field is critical and may be lifesaving. The critical care interventions performed by physicians in drowning management are poorly described. The aim was to describe patient characteristics and critical care interventions with 30-day mortality as the primary outcome in drowning patients treated by the Danish Air Ambulance.

METHODS

This retrospective cohort study with 30-day follow-up identified drowning patients treated by the Danish Air Ambulance from January 1, 2016, through December 31, 2021. Drowning patients were identified using a text-search algorithm (Danish Drowning Formula) followed by manual review and validation. Operational and medical data were extracted from the Danish Air Ambulance database. Descriptive analyses were performed comparing non-fatal and fatal drowning incidents with 30-day mortality as the primary outcome.

RESULTS

Of 16,841 dispatches resulting in a patient encounter in the six years, the Danish Drowning Formula identified 138 potential drowning patients. After manual validation, 98 drowning patients were included in the analyses, and 82 completed 30-day follow-up. The prehospital and 30-day mortality rates were 33% and 67%, respectively. The National Advisory Committee for Aeronautics severity scores from 4 to 7, indicating a critical emergency, were observed in 90% of the total population. They were significantly higher in the fatal versus non-fatal group (p < 0.01). At least one critical care intervention was performed in 68% of all drowning patients, with endotracheal intubation (60%), use of an automated chest compression device (39%), and intraosseous cannulation (38%) as the most frequently performed interventions. More interventions were generally performed in the fatal group (p = 0.01), including intraosseous cannulation and automated chest compressions.

CONCLUSIONS

The Danish Air Ambulance rarely treated drowning patients, but those treated were severely ill, with a 30-day mortality rate of 67% and frequently required critical care interventions. The most frequent interventions were endotracheal intubation, automated chest compressions, and intraosseous cannulation.