Outcomes, data extraction and analysis

Primary outcome measure was prevalence of patent versus obstructed airway for short and long burials reported in percentage of cases. Burial duration was defined as short if < 35 min and long if ≥ 35 min, as no victims were reported to have survived burials longer than 35 min with an obstructed airway [7, 14]. Secondary outcome measures were the rates of a present air pocket and survival in percentage of cases, both in relation to burial time and airway status.

One reviewer (FE) extracted the data from the selected studies. Identified literature was sought for data reporting patients’ airway status (defined as patent, obstructed or unknown) after critical burial. Additionally, studies were screened for burial duration, mortality and information on the presence of an air pocket which was included in the final analysis of secondary outcomes. Some studies further categorised data on airway status as “not documented, but intubated or ventilated” or “not documented and not intubated/ventilated”, these cases were added to the unknown airway category.

Raw data was used for data extraction where available. Data was charted in tables for every category and publication (separated for retrospective studies, case reports, and additional databases) in Microsoft Excel (Microsoft Corporation, Redmond, USA) and analysed with SPSS statistics software version 28.0. (IBM Corp., Armonk, USA). Odds ratio (OR) was calculated to assess the correlation between airway patency, the presence of an air pocket and survival.