To understand if a progressive increase in end-tidal carbon dioxide (CO2) levels are heralding respiratory difficulties before desaturation measured from capnography in obstructive sleep apnea patients, with the use of nasal prongs, transcutaneous monitors, Capnostream, and Massimo technologies.

Background and Significance Carbon dioxide (CO2) levels can be monitored throughout the respiratory cycle via capnography. In this way, capnography allows healthcare professionals to follow a number of respiratory factors (i.e., depression, apnea, and hypercapnia) in real-time. Earlier detection of alterations to ventilation status will better enable providers to more accurately dose medications during procedures, especially in at-risk patient populations such as patients with obstructive sleep apnea (OSA) [1, 2].

In a recent study of bariatric patients, approximately 15% experience postoperative pulmonary complications. These patients could benefit significantly from capnography monitoring as this measure can very accurately estimate the prevalence of respiratory complications.

Through this study we seek to understand how end-tidal CO2 (ETCO2) levels of patients with obstructive sleep apnea vary when patients are in the post-anesthesia care unit (PACU). By collecting information on patient outcomes, we hope to better understand the value of this monitoring technique in an at-risk patient population. Though capnography in the PACU has not previously been demonstrated to improve patient safety or satisfaction, capnography has never been studied in a population of patients who are at risk of obstructive sleep apnea.

Study Design This is a prospective, blinded observational pilot study to monitor if changes in end-tidal CO2 levels provide incremental value over pulse oximetry when detecting respiratory difficulties (i.e., hypercapnia).

Inclusion Criteria:

• > 18 years of age
• Patients who have are at TGH for bariatric surgery
• BMI > 30
• At risk of obstructive sleep apnea according to TGH STOP-BANG questionnaire

Exclusion Criteria:

• <18 years of age
• Not at risk of obstructive sleep apnea according to TGH STOP-BANG questionnaire

Patients at high-risk of obstructive sleep apnea undergoing gastric bypass surgery