Matthias Görges1,2, Nicholas C West1, Wesley Cheung1,3, Guohai Zhou4, Firoz Miyanji5, Simon D Whyte1. 1. Department of Anesthesiology, Pharmacology and Therapeutics, The University of British Columbia, Vancouver, BC, Canada. 2. Pediatric Anesthesia Research Team, Child and Family Research Institute, Vancouver, BC, Canada. 3. School of Medicine and Dentistry, The University of Aberdeen, Aberdeen, Scotland. 4. Department of Statistics, The University of British Columbia, Vancouver, BC, Canada. 5. Department of Orthopaedics, The University of British Columbia, Vancouver, BC, Canada.
Abstract
BACKGROUND: Underbody forced air warming is a method commonly used for intraoperative temperature maintenance in children. We previously reported that preoperative forced air warming of children undergoing spinal surgery substantially reduces the incidence and duration of intraoperative hypothermia (<36°C). OBJECTIVE: The aim of this study was to evaluate the effects of preoperative warming before spinal deformity surgery on surgical site infection rate, length of hospitalization, and bleeding (estimated blood loss and incidence of cell salvaged and/or allogeneic packed red blood cell transfusions). METHODS: Demographic, anesthetic, and surgical data of all patients who underwent spinal deformity surgery between December 2009 and December 2012 were obtained by retrospective chart review. Temperature data were abstracted from an existing repository; the incidence and duration of hypothermic episodes were identified. For each outcome, logistic regression models and propensity score analysis were used to estimate the effect of prewarming, adjusted for potential confounders. The issue of missing data was handled by a multiple imputation method. Data from 334 procedures were used in modeling and propensity score stratification. RESULTS: Adjusted odds ratios for the effects of prewarming were 0.47 (95% CI 0.15-1.49) for surgical site infections; 0.89 (95% CI 0.55-1.41) for cell salvaged blood transfusion; 0.43 (95% CI 0.22-0.83) for allogeneic packed red blood cell transfusion; and 1.24 (95% CI 0.77-1.99) for a length of hospitalization >6 days. Adjusted mean decrease in estimated blood loss for prewarming was 72 (95% CI -29 to 173) ml. CONCLUSION: In this study, prewarming was associated with a reduction in allogeneic packed red blood cell transfusion. However, no causal relationship between prewarming and reduced allogeneic blood transfusion should be assumed. Prewarming was not associated with reductions in estimated blood loss, length of hospitalization, or the incidence of surgical site infection.
BACKGROUND: Underbody forced air warming is a method commonly used for intraoperative temperature maintenance in children. We previously reported that preoperative forced air warming of children undergoing spinal surgery substantially reduces the incidence and duration of intraoperative hypothermia (<36°C). OBJECTIVE: The aim of this study was to evaluate the effects of preoperative warming before spinal deformity surgery on surgical site infection rate, length of hospitalization, and bleeding (estimated blood loss and incidence of cell salvaged and/or allogeneic packed red blood cell transfusions). METHODS: Demographic, anesthetic, and surgical data of all patients who underwent spinal deformity surgery between December 2009 and December 2012 were obtained by retrospective chart review. Temperature data were abstracted from an existing repository; the incidence and duration of hypothermic episodes were identified. For each outcome, logistic regression models and propensity score analysis were used to estimate the effect of prewarming, adjusted for potential confounders. The issue of missing data was handled by a multiple imputation method. Data from 334 procedures were used in modeling and propensity score stratification. RESULTS: Adjusted odds ratios for the effects of prewarming were 0.47 (95% CI 0.15-1.49) for surgical site infections; 0.89 (95% CI 0.55-1.41) for cell salvaged blood transfusion; 0.43 (95% CI 0.22-0.83) for allogeneic packed red blood cell transfusion; and 1.24 (95% CI 0.77-1.99) for a length of hospitalization >6 days. Adjusted mean decrease in estimated blood loss for prewarming was 72 (95% CI -29 to 173) ml. CONCLUSION: In this study, prewarming was associated with a reduction in allogeneic packed red blood cell transfusion. However, no causal relationship between prewarming and reduced allogeneic blood transfusion should be assumed. Prewarming was not associated with reductions in estimated blood loss, length of hospitalization, or the incidence of surgical site infection.