Acidosis as a promising early indicator of mortality among point-of-care parameters and vital signs in non-traumatic critically ill patients.

Background: The management of critically ill patients, arriving at the emergency department (ED), requires structured care in critical care facilities, particularly in the resuscitation room. This study examines the significance of initial vital signs and blood gas analysis (BGA)-derived values as clinically useful early indicators of mortality risk in critically ill patients, both during in the resuscitation room care and within the following 30 days, with a focus on evaluating the individual predictive performance of accessible clinical parameters.

Methods: We pooled data from two consecutive retrospective observational studies in a German university ED to analyze an unselected patient population of non-traumatic critically ill patients. Vital signs, such as heart rate, systolic blood pressure, and BGA values (including pH, bicarbonate, carbon dioxide, glucose, lactate, electrolyte levels) on admission to the ED, were used to estimate the impact on both resuscitation room and 30-day mortality.

Results: In 1,536 critically ill patients, pH, lactate and bicarbonate were found to be potential predictors of resuscitation room mortality. In contrast, vital signs showed limited reliability in predicting outcomes. Of all tested variables, pH demonstrated the highest area under the curve (AUC) value among the analyzed markers for resuscitation room mortality (AUC 0.81 [95% CI 0.75-0.87]). However, the AUC of pH for 30-day mortality decreased to 0.64 ([0.6 - 0.68], indicating a complex interplay of factors influencing long-term outcome. A subgroup analysis based on pH showed a substantial increase in resuscitation room and 30-day mortality for patients with a pH below 7.2 as well as a second increase below 7.0.

Conclusion: Our study highlights important parameters for the assessment of critically ill patients at ED admission that are helpful for formulating immediate medical decisions. Acidosis on the initial BGA appears to be a relevant prognostic marker for mortality in critically ill, non-traumatic patients and may aid in early risk assessment, regardless of the underlying condition. Early detection of acidosis could facilitate rapid decision-making and timely identification of patients requiring intensive care.