Observational study of Mallampati changes after prone spinal surgery.

Study Objective: To evaluate airway changes in patients undergoing surgery in the prone position.

Design: Single-arm observational study.

Patients: Patients between 18 to 65 years old, scheduled for prone spinal surgery; 74 patients were enrolled and 54 patients were analyzed.

Intervention: The initial airway examination was graded according to the Samsoon and Young modification of the Mallampati classification (MMP). Airway photographs were obtained in a standardized manner and were repeated 20 minutes after extubation. The photographs were then randomized.

Measurements: Subjects' age, gender, race, weight, duration of surgery, amount of crystalloid fluid given, and estimated blood loss were recorded. Three senior anesthesiologists who were blinded to the origin of the photographs analyzed and graded the airways.

Main Results: All statistical tests showed significance between pre-MMP and post-MMP scores (P<0.001). There was no difference between pre and post interobserver MMP scores. The MMPs of 12 patients (22%) did not change and MMP scores were changed in 42 patients (78%): 30 (71%) patients by one class, 10 (24%) patients by two classes, and two patients (5%) by three classes. There was no correlation between patients whose MMP was changed and length of surgery or crystalloid administered.

Conclusion: Modified Mallampati scores increased in the majority of patients after spinal surgery in the prone position.