RELATION BETWEEN RESPIRATORY SUPPRESSION FROM SEDATION DURING ENDOSCOPY AND VITAL CAPACITY

Background:  Respiratory suppression is observed during endoscopy under sedation. If respiratory suppression can be predicted before endoscopy, incidental complications can conceivably be prevented. In the present study, we focused on the relation between respiratory suppression from sedation and lung function. Methods:  A total of 211 patients underwent respiratory function tests before the surgical operation and gave written informed consent individually to participate in this study. We investigated the relation between respiratory suppression from sedation and lung function. During the endoscopic procedure, when blood oxygen saturation (SpO2) fell to below 90%, the patient was evaluated as ‘respiratory suppression present’. Results:  Sedation lowered SpO2 by an average of 6.0%, and was significantly lower than the prior to sedation blood oxygen saturation (PreSpO2). Compared to patients with SpO2 maintained up to 90%, patients with SpO2 fallen below 90% were significantly older, shorter in stature, lighter in bodyweight, and more commonly female. Furthermore, respiratory suppression from sedation was influenced by vital capacity (VC) and PreSpO2. Multivariate analysis was performed, and the receiver operating characteristic (ROC) curve constructed for the respiratory suppression prediction model based on age, height, VC and PreSpO2 yielded area under the curve (AUC) of 0.79. As VCpredict can be calculated from age and height, the three variables of age, height and VC in the above model were substituted with VCpredict resulting in a two-factor model based on VCpredict and PreSpO2. The ROC curve of the two-factor model had AUC of 0.77, which was slightly decreased but by no means inferior. Conclusion:  Predicting respiratory suppression from VCpredict and PreSpO2 is clinically relevant with the additional benefit of simplicity.