Predictors of outcome in dogs undergoing thoracic surgery (2002-2011)

Abstract

Objective: To evaluate mortality in a canine population undergoing thoracic surgery and identify factors which may be associated with outcome. Study design: Retrospective cohort study. Animals: 286 dogs anaesthetized for thoracic surgery at the Royal Veterinary College between June 2002 - June 2011. Methods: Variables examined included: signalment; ASA status; nature of disease; presence of co-morbidities; pre-anaesthetic oxygen requirement; surgical approach; anaesthesia management [anaesthetic agents; requirement for thoracocentesis; central venous pressure measurement; duration of surgery and anaesthesia; use of colloids, blood products, inotropes or neuromuscular blocking agents (NMBA)]. Outcome was defined as either non-survival to 24 hours after surgery or (having survived to 24 hours) to discharge. Univariate and multivariable logistic regressions were performed to identify risk factors associated with non-survival. Results: Overall non-survival (excluding those euthanased) to discharge was 5.9%. Non-survival was 2.2% at 24 hours and 3.6% at time of discharge. Non-survival to 24 hours was associated with pre-anaesthetic oxygen requirement (odds ratio (OR) 12.2 [95% CI 1.8-84.5]) and NMBA use (OR 9.6 [95% CI 1.6-57.9]). Non-survival to discharge was associated with surgical duration, with surgeries >180 minutes having OR 16.9 [95% CI 2.0-144.0] compared to surgeries ≤90 minutes and blood product use (OR 4.6 [95% CI 1.3-14.6]). No association was found between ASA category and non-survival at 24 hours (OR 1.4 [95% CI 0.2-11.7]) or discharge (OR 4.4 [95% CI 0.6-34.3]). Significant associations were found between NMBA use and ASA category (p = 0.046), surgical duration (p = 0.002), use of colloids (p = 0.011), blood products (p = 0.001) and inotropes and/or vasopressors (p < 0.001). Conclusions and clinical relevance: Variables significantly associated with non-survival from canine thoracic surgery at 24 hours include NMBA use and pre-anaesthetic oxygen requirement. Blood product use and increasing surgical duration were associated with non-survival to hospital discharge. The associations may relate to the need for such products in the most complicated cases. © 2013 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.