Objective: To prospectively investigate data specific to 9 risk factors for significant association with airway managementrelated lip injuries during surgery.
Material and Method: Two hundred and seventy patients (90 cases and 180 controls) who underwent surgeries at Siriraj Hospital from September 2015 to July 2016 were enrolled. Ninety patients (injured group) sustained lip injury after surgery. Each case was matched with two cases without lip injury by gender, age, and operation date. One hundred and eighty patients without lip injury were recruited as control group. Data specific to 9 risk factors were evaluated for significant association with airway management-related lip injuries during surgery.
Results: Most patients recovered from their lip injury within three days after operation, but 8 patients or 8.4% required as long as 5 days for their lip injury to completely heal. Predisposing factors associated with airway management-related lip injuries in univariate analysis were Mallampati grade >1, dental problems, performed by nurse anesthetist, training duration <3 months and 3 to 6 months, and oral procedure. Significant factors associated with airway management-related lip injuries in multivariate analysis were dental problems (OR 8.9, 95% CI 1.46 to 4.21, p = 0.001), training duration <6 months (OR 16.2, 95% CI 4.2 to 62.5, p<0.001) and oral procedure (OR 19.3, 95% CI 3.5 to 105.8, p = 0.001).
Conclusion: Preexisting dental problems, oral procedures, and airway management performed by an operator with less than six month training are risk factors for airway management related injuries. Careful protection and closed observation should be particularly concerned.

Keywords: Lip injuries, Anesthesia, Risk factors