August 18, 2016
Hip fractures are common orthopedic injuries, and the incidence is projected to increase substantially in the near future.1,2 Not only are hip fractures common, they are also associated with poor prognosis and 1-year mortality rates ranging from 20% to 30%.3,4 Beyond mortality, survival after hip fracture significantly decreases patient independence and quality of life and increases the burden on the health care system.5,6
There has been an enhanced focus on reducing surgical complications, demonstrated by guidelines published by the World Health Organization (WHO), the Agency for Healthcare Research and Quality (AHRQ), and the Surgical Care Improvement Project (SCIP).7–9 Poor clinical outcomes and significant financial burden associated with potentially avoidable complications have been the drivers of these measures.10–12 Patients who sustain hip fractures have significant morbidity and mortality prior to considering other perioperative complications. For this reason, hip fractures have been the focus of adherence to guidelines aimed at reducing complications. All of the aforementioned guidelines recommend maintenance of normothermia (defined as body temperature greater than 36°C) in the immediate perioperative period.7–9
Whereas most recommendations in these guidelines are supported by an abundance of evidence, the rationale for the recommendation of normothermia is based on evidence outside the field of orthopedics and has been generally applied to all surgical patients.13 Evidence indicates that perioperative hypothermia may (1) impair wound healing and increase the risk of surgical-site infection, (2) increase intraoperative blood loss and need for transfusion, and (3) increase cardiovascular morbidity.14–26 Interestingly, the effect perioperative normothermia plays in outcomes associated with orthopedic surgical procedures, and specifically hip fractures, has limited overall evidence.27,28 The purpose of the current study was to determine the incidence of mean intraoperative hypothermia during surgical fixation of hip fractures at the authors’ institution and to evaluate the effect of hypothermia on complications and outcomes in the immediate postoperative period.
Materials and Methods
Under institutional review board approval, a retrospective chart review was performed on records from 1541 consecutive patients who underwent operative treatment of a hip fracture at the authors’ institution between January 2005 and October 2013. In the initial query, patients who had less than 6 weeks of follow-up, death within 6 weeks of presentation, or incomplete perioperative data were excluded. Data were collected from 2 academically affiliated hospitals, one a large, urban tertiary care center and the other a suburban community hospital in a large metropolitan area. After excluding patients who had multiple injuries requiring additional surgical intervention, a total of 1525 patients were included in the analysis. A total of 974 (63.8%) patients had an intertrochanteric (IT) fracture and 551 (36.2%) patients had a femoral neck (FN) fracture.
Three independent reviewers (A.M.P., T.R.J., J.S.) collected data and performed extensive chart reviews of the included patients. The following data were recorded: patient demographic data, including age, sex, race, diagnosis, and surgical procedure and side; basic clinical data, including preoperative hemoglobin, medical comorbidities, and American Society of Anesthesiologists (ASA) classification; and surgery-specific data, including operative time, use of intraoperative active rewarming device, perioperative temperature measurements, estimated intraoperative blood loss (EBL), intraoperative intravenous fluid (IVF) administration, length of hospital stay (LOS), requirement for postoperative transfusion, and 30-day readmission rates. Temperature measurements were obtained from the anesthesia record. Prior to November 2012, anesthesia records were hand recorded and uploaded to patients’ electronic medical record. After November 2012, the authors’ institution transitioned to an electronic record that included electronic anesthesia records. Hypothermic patients were defined as those who demonstrated a mean intraoperative temperature less than 36°C.
Postoperative complications recorded included superficial (SSSI) and deep surgical-site infection (DSSI), nonsurgical-site infection (NSSI), symptomatic deep venous thrombosis (DVT), pulmonary embolism (PE), myocardial infarction (MI), and stroke. Superficial infection was defined as infection superficial to the fascia. Patients were identified as having DSSI if the infection was deep to the fascia and if they required reoperation including deep irrigation and debridement and/or removal of components for infection. Nonsurgical-site infection was defined as systemic infection anatomically distant to the surgical site requiring antibiotic treatment. Patients wore intermittent pneumatic compression devices during their hospital stay and received chemical VTE prophylaxis postoperatively. All patients received a dose of prophylactic antibiotics 60 minutes prior to surgical incision, and dosing continued 24 hours postoperatively.
