Vital signs preceding in-hospital cardiac arrest: a matched case-control study

Hospitalised patients undergo routine vital sign measurements to detect clinical deterioration. Research into vital signs prior to in-hospital cardiac arrest is crucial, as early detection of deterioration can enable timely intervention and potentially prevent cardiac arrest. This study aimed to investigate the association between vital signs and the risk of in-hospital cardiac arrest.

We conducted a registry-based, matched case-control study, including cases with in-hospital cardiac arrest and hospitalised patients as controls, in the Central Denmark Region from 2017 to 2022. Exposures were values of heart rate, systolic and diastolic blood pressure, body temperature, respiratory rate, level of consciousness, SpO₂, pulse pressure, SpO₂/FiO₂ ratio, and National Early Warning Score (NEWS) 2. Conditional logistic regression was used to assess the association between continuous and categorical values of vital sign measurements and the risk of in-hospital cardiac arrest.

The study population consisted of 1587 cases and 10,276 controls. The risk of in-hospital cardiac arrest increased incrementally for increasing heart rate, body temperature, respiratory rate, and NEWS 2 score, and decreasing systolic and diastolic blood pressure, body temperature, SpO₂, pulse pressure, and SpO₂/FiO₂ ratio. Associations were most pronounced for systolic blood pressure ≤80 mmHg (OR 15.3 [95 % CI: 9.44-24.7]), SpO₂/FiO₂ ≤ 2.50 (OR 14.1 [95 % CI: 10.3-19.2]), and NEWS 2 score ≥7 points (OR 11.7 [95 % CI: 9.57-14.3]) compared to normal reference values.

The risk of in-hospital cardiac arrest increases incrementally with the degree of vital sign abnormality.