Transcutaneous CO₂/O₂ and CO₂/air suction in patients undergoing cataract surgery with retrobulbar anaesthesia

We investigated transcutaneous partial CO₂ and O₂ pressures and respiratory rate in unpremedicated elderly patients of ASA physical status 1 to 3 who underwent cataract surgery under retrobulbar anaesthesia. In group A no air suction was used. In group B suction was applied under the sterile drapes to avoid rebreathing of CO₂. In group A transcutaneous partial CO₂ pressure and respiratory rate significantly increased compared with baseline, whereas in group B they remained constant. In both groups transcutaneous partial O₂ pressure and oxygen saturation as measured by pulse oximetry significantly rose after insufflating oxygen 3 lmin⁻¹. Heart rate and mean arterial blood pressure remained constant. Our results demonstrate that the application of suction near the patient's head prevents CO₂ rebreathing and subsequent hypercapnia associated with an elevated respiratory rate. The use of suction makes it unnecessary to raise oxygen administration. Suction combined with monitoring of partial CO₂ pressure using transcutaneous sensors should be used in all ophthalmological operations under retrobulbar anaesthesia.