Abstract
Lower-extremity orthopaedic procedures may be performed under either regional or general anaesthesia, or a combination of both techniques. There is a growing body of evidence supporting the benefits of regional anaesthesia, with meta-analyses of randomised controlled trials and registry data suggesting decreases in deep surgical site infections, thromboembolic events, cardiopulmonary complications and length of stay associated with use of regional anaesthesia. In patients undergoing foot and ankle surgery specifically, there is evidence demonstrating decreased post-operative pain, nausea, vomiting, opioid use and unplanned hospital admission. This supports an increased role for the use in regional anaesthesia in patients undergoing foot and ankle surgery. However, the type of anaesthetic used is dependent on surgeon, patient, anaesthesiologist and institutional factors. The purpose of this study is to investigate pre-operative factors that predict the type of anaesthetic used in patients undergoing foot and ankle surgery.
Data was collected prospectively on 888 patients undergoing foot or ankle surgery at a single institution. The primary method of anaesthesia for each procedure was recorded. Ten additional variables were recorded and analysed: age, BMI, gender, diabetes, ASA status, procedure length, procedure start time, elective vs. trauma procedure, primary vs. revision procedure and preoperative anticoagulation. Logistic regression modelling was performed to identify factors that independently predict the type of anaesthetic used.
General anaesthetic was employed in 280 patients (32%), and regional anaesthesia was the primary anaesthetic type used in 608 (68%). Logistic regression modelling demonstrated that factors that independently predict use of general anaesthetic include younger age (p<0.0001; Odds Ratio 0.97/year), male sex (0.0033; 1.618), procedure start time (0.0319; 1.066/hour) and length of procedure (<0.0001; 1.520/hour). Patients who underwent general anaesthetic had a mean length of procedure of 108 +/− 77 minutes, whereas patients provided with regional anaesthesia had a mean length of procedure 83 +/− 64 minutes.
With increasing evidence supporting the benefits of regional anaesthesia in patients undergoing lower extremity surgery, it is important to identify modifiable factors that contribute to patients receiving alternative treatments. Since later procedure start time was identified as an independent predictor of general anaesthetic use, there may be a role for identifying patients at increased risk of complications associated with general anaesthesia and scheduling earlier start times. Furthermore, while it is logical that extended length of procedure may be a contraindication to regional anaesthesia, the mean procedure time of 108 minutes in the general anaesthesia group indicates that many of these patients should still be considered candidates for regional anaesthesia.
