Hyun Jung Lee,1 Ji Seon Chae,2 Sang-Mee An,2 Hye-Won Oh,1 Youn Jin Kim,1 Jae Hee Woo1 1Department of Anesthesiology and Pain Medicine, College of Medicine, Ewha Womans University, Seoul, South Korea; 2Department of Anesthesiology and Pain Medicine, Ewha Womans University Seoul Hospital, Seoul, South KoreaCorrespondence: Jae Hee Woo, Department of Anesthesiology and Pain Medicine, College of Medicine, Ewha Womans University, 260 Gonghangdaero, Gangseo-gu, Seoul, 07804, South Korea, Tel +82-2-6986-4300, Fax +82-2-6986-4960, Email jheewoo@ewha.ac.krPurpose: Monitoring end-tidal carbon dioxide partial pressure (PETCO2) is a noninvasive, continuous method, but its accuracy is reduced by prolonged capnoperitoneum and the steep Trendelenburg position in robot-assisted radical prostatectomy (RARP). Transcutaneous carbon dioxide partial pressure (PTCCO2) monitoring, which is not affected by ventilatorâ perfusion mismatch, has been suggested as a suitable alternative. We compared the agreement of noninvasive measurements with the arterial carbon dioxide partial pressure (PaCO2) over a long period of capnoperitoneum, and investigated its sensitivity and predictive power for detecting hypercapnia.Patients and Methods: The patients who underwent RARP were enrolled in this study prospectively. Intraoperative measurements of PETCO2, PTCCO2, and PaCO2 were analyzed. The primary outcome was the agreement of noninvasive monitoring with PaCO2 during prolonged capnoperitoneum. Bias and precision between noninvasive measurements and PaCO2 were assessed using Blandâ Altman analysis. The bias and mean absolute difference were compared using a two-tailed Wilcoxon signed-rank test for pairs. The secondary outcome was the sensitivity and predictive power for detecting hypercapnia. To assess this, the Yates corrected chi-square test and the area under the receiver operating characteristic curve were used.Results: The study analyzed 219 datasets from 46 patients. Compared with PETCO2, PTCCO2 had lower bias, greater precision, and better agreement with PaCO2 throughout the RARP. The mean absolute difference in PETCO2 and PaCO2 was larger than that of PTCCO2 and PaCO2, and continued to exceed the clinically acceptable range of 5 mmHg after 1 hour of capnoperitoneum. The sensitivity during capnoperitoneum and overall predictive power of PTCCO2 for detecting hypercapnia were significantly higher than those of PETCO2, suggesting a greater contribution to ventilator adjustment, to treat hypercapnia.Conclusion: PTCCO2 monitoring measured PaCO2 more accurately than PETCO2 monitoring during RARP requiring prolonged capnoperitoneum and a steep Trendelenburg position. PTCCO2 monitoring also provides more sensitive measurements for ventilator adjustment and detects hypercapnia more effectively than PETCO2 monitoring.Keywords: intraoperative carbon dioxide monitoring, capnoperitoneum, robotic surgery, end-tidal carbon dioxide monitoring, general anesthesia

Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submission Application for ESRA Abstract Prizes: I apply as an Anesthesiologist (Aged 35 years old or less) Background and Aims The beach-chair position (BCP) is commonly used for shoulder surgery but is known to increase hypotension incidence. Older age and interscalene brachial plexus block (ISB) have also been identified as risk factors for hypotension during BCP. As altered blood pressure control mechanisms and autonomic dysfunction, which cause hypotension, are more likely to occur in frail older patients, we investigated the association between preoperative frailty and hypotension during BCP in older patients. Methods Patients aged ≥ 65 years who underwent elective total shoulder arthroplasty in BCP under general anesthesia with preoperative ISB were included. The frailty of participants was assessed before surgery using the Reported Edmonton Frail Scale. Quadriceps depth was measured by ultrasound preoperatively, and values < 2.3cm were considered significant. Hypotension was defined as a mean blood pressure < 65mmHg or a decrease of ≥ 20% from baseline. Results Data were analyzed from 46 patients (mean age: 72.8 yrs). The incidence of hypotension during BCP was 71.7% (non-frail/prefrail/frail; 70.3%, 80% and 100%). A decreased quadriceps depth < 2.3cm was an independent risk factor for hypotension during BCP (odds ratio, 8.49, 95% confidence interval [CI], 1.38 – 51.90). The predictive power of hypotension during BCP was higher when both frailty and quadriceps depth were considered together, compared to considering frailty alone (AUC [95% CI], 0.766 [0.60-0.89] vs 0.51 [0.35-068], p=0.01). Conclusions A reduced quadriceps depth is associated with hypotension during BCP. Assessing both frailty and quadriceps depth may enhance the screening tool for identifying older patients at risk of developing hypotension during BCP. Attachment CRIS.pdf