Perioperative anesthesia related mortality: a retrospective cohort study with 11.562 anesthetics procedures 

Introduction:  Studying the postoperative in-hospital mortality rate is crucial to understanding the perioperative care process failures and implementing strategies that improve patient outcomes. Anesthesia-related perioperative deaths are rare and have been declining over the past 50 years. However there are a small number of patients at high-risk for complications and death that would benefit with a new approach. 

Objectives: To evaluate the incidence, preoperative risks factors, and classify the cause of perioperative deaths up to 30 days of procedures requiring anesthesia. 
Methods: A retrospective cohort study was performed at a reference university Hospital in south Brazil evaluating the data related to pre, trans, and postoperative characteristics of surgical patients between January, 2012 and December, 2013. The details of the surgery and anesthesia from those inpatients that died post-surgery were ascertained from the Information Management System. Deaths were reviewed and classified by three Anesthesiologists (according to ANZCA Classification) into three major groups: Attributable to Anesthesia, Not Related to Anesthesia, and Unassessable Death. 
Results: A total of 11562 surgeries were performed resulting in 321 (2,77%) 30-day perioperative death. Most deaths occurred after 48 hours (76,6%) in patients ASA physical state 3 or higher (86,9%) submitted to major (59,2%) urgent (54,4%) surgeries, in which a small death percentage was attributable to anesthesia (0,6%) or had apparent anesthesia contribution (3,8%). Most of the deaths were classified as inevitable and have occurred irrespectively of anesthesia or surgical procedures (50%). Surgical contribution was pointed in 25,3% of the death cases, and 16,3% were considered incidental death, which was not related to the indication for surgery and was not due to factors under the control of the anesthetist or surgeon. The death attributable to anesthesia was due to pulmonary aspiration and those with possible anesthesia contribution were related to inappropriate adverse event management. Sepsis was the most final death case (45,3%) followed by advanced cancer (20,6%). The procedure most frequent was Exploratory laparotomy (21,8%) followed by arterial by-pass and colorectal resection. 
Conclusion:  The qualitative analysis of perioperative deaths contributes to the recognition of assistance  failures and to define plans to prioritize the most problematic areas that could be improved. Our study confirmed that death attributable to anesthesia is a rare event, therefore it signalizes the urgent necessity to advance in the perioperative care of patients scheduled to exploratory laparotomies, specially those associated to sepsis.