Perioperative mortality related to anesthesia within 48 h and up to 30 days following surgery: A retrospective cohort study of 11,562 anesthetic procedures.

STUDY OBJECTIVE: Studying postoperative in-hospital mortality is crucial to the understanding of the perioperative process failures and to the implementation of strategies to improve patient outcomes. We intend to classify the causes of perioperative deaths up to 30 days after procedures requiring anesthesia and to evaluate the risk factors for early (48 h) or late (30 day) mortality.

DESIGN: Retrospective cohort study.

SETTING: A quaternary University Hospital from South Brazil.

PATIENTS: The information related to the perioperative care was collected from surgeries performed between January 2012 and December 2011.

INTERVENTIONS: None (observational study).

MEASUREMENTS: Three anesthesiologists classified the causes of deaths according to the ANZCA (Australian and New Zealand College of Anesthetists) classification, used in the report of Anesthesia-Related Mortality in Australia since 1985, which defines eight death categories. The risk factors for early or late death were analyzed in a regression model.

MAIN RESULTS: 11.562 surgeries were performed, with a mortality incidence of 2.75% within 30 days (319 deaths). Most deaths were inevitable (50.7%), as they were related to advanced illnesses and would occur regardless of anesthetic or surgical procedures. The second most common cause was related to surgical complications (25%). The death rate having anesthesia as a likely contributor was 1.72:10.000 procedures, and as a potential contributor 7.78:10.000. These deaths occurred significantly earlier (<48 h) when compared to deaths from other causes. Transoperative vasopressor, extremes of age and out-of-hour surgery were independent variables associated to early deaths.

CONCLUSIONS: The study confirms that postoperative mortality in which anesthesia was involved occurred earlier in the perioperative period. In addition, it was revealed that this involvement of anesthesia as a morbidity contributor shows higher frequency when considering the anesthesiologist perioperative role, and when assessing the mortality in the long term (30 days).