Characteristics and outcomes of medical emergency team calls in a Swiss tertiary centre - a retrospective observational study

To describe reasons for medical emergency team (MET) activation over time, to analyse outcomes, and to describe the circadian distribution of MET calls and Intensive Care Unit (ICU) admissions following MET activation.

Monocentric retrospective observational study of prospectively collected data on all MET calls between 1^st of January 2012 until 31^st of May 2019. We analysed data on baselines, referring wards, and disposition of all MET patients. In addition, we allocated all MET calls to the hourly intervals over the 24-hour cycle of the day in order to identify peak times of team activation.

A total of 4068 calls in 3277 patients (37% female, n = 1210) were analysed. The mean age was 65.9 years (± 15.7). The MET dose (defined as MET calls/1000 hospital admissions) remained relatively stable over the years with a median of 8.0 calls/1000 hospitalisations (interquartile range [IQR] 7.0-10.0). A total of 2526 calls (62%) occurred out of hours (17:00 to 8:00). The hourly rate of MET activations was greatest during the evening shift (33.8% of calls in seven hours), followed by the day shift (35.8% calls in nine hours) and night shift (30.4% in eight hours). Over the years, staff concern was the main reason for a MET call (n = 1192, 34%), followed by low peripheral oxygen saturation (SpO₂) not responding to oxygen therapy (n = 776, 22%). Abnormal respiratory rate was a trigger to call the MET in 44 cases (1.3%), and was not documented prior to 2017. Overall, in-hospital mortality was 22%.

While most common reasons for MET calls over the years were staff concern and low SpO₂, abnormal respiratory rate was the least frequent, but increased after the introduction of the quick sequential organ failure assessment (qSOFA) in 2016. Most MET calls occurred out of hours with peak hours during the evening shift, highlighting the importance of resource allocation during this shift when planning to introduce a MET system in a hospital. In-hospital mortality after a MET call was 22%.