Authors (including presenting author) :
Wong MN(1), Lai SK(2), Tang GCH(3), Li K (3)
Affiliation :
(1)Operating Room, Nursing Services Division, United Christian Hospital, Kowloon East Cluster, (2)Operating Room, Department of Anesthesiology, Pain Medicine & Operating Services, United Christian Hospital, KEC (3)Ophthalmology Department, United Christian Hospital, KEC
Introduction :
Since the Coronavirus disease 2019 (COVID-19) outbreak, patients undergoing ophthalmic surgery under local anaesthesia should wear taped surgical mask to minimize the risks of cross-contamination to perioperative personnel. Under surgical masks, an oxygen flow rates of 2L/min of nasal-cannulated supplemental oxygen is commonly given in our routine practice. However, pooling of an oxygen-enriched atmosphere (OEA) will increase the likelihood and intensity of surgical fire when using electrosurgical unit.
Objectives :
To investigate the combined effects of taped surgical masks, drape tenting, tenting methods, flow rates of supplemental oxygen on reducing the oxygen concentration being accumulated under surgical drapes.
Methodology :
In Part I, where a mannequin simulation of a patient undergoing ophthalmic surgery with 2L/min supplemental oxygen was used, we investigated how different configurations of (1) taped surgical masks (complete, three side, upper side); (2) drape tenting (no tenting, tenting); (3) tenting methods (drapes lifted up by IV pole lie parallel with OT bed, IV pole lie 45⸰ inside OT bed) would affect oxygen accumulation under surgical drapes in an experimental setting. Based on Part I results, Part II recruited 5 healthy volunteer subjects to investigate how varying flow rates (0, 1, 2, 3, 4 L/min) of supplemental oxygen given via nasal cannula would affect oxygen accumulation.
Result & Outcome :
Part I showed that oxygen concentration under surgical drapes was the lowest (36%) with the following settings: an upper side taped surgical mask, drape tenting and draping lifted up by IV pole lie 45⸰ inside OT bed. Part II results indicated that oxygen flow rates of 2L/min produced alarmingly elevated oxygen concentration (26.36% ± 2.19%). Apart from our routine practice, all volunteers did not have any indications of oxygen desaturation without supplemental oxygen, and oxygen concentration under surgical drapes (19.00% ± 1.20%) was lower than oxygen concentration in ambient air (21%), which is safe for using electrosurgical unit during procedure. According to the study evidences, no supplemental oxygen given was being piloted in Aug 2021. Almost 100% of patients undergoing ophthalmic surgery under local anaesthesia did not have any indications of oxygen desaturation and were free from oxygen-enriched atmosphere (OEA) while using electrosurgical unit. Navigating change of practice has been successfully implemented in Oct 2021 for enhancing clinical safety on preventing surgical fires.
