Oxygen application by a nasal probe prevents hypoxia but not rebreathing of carbon dioxide in patients undergoing eye surgery under local anaesthesia

Background/aim-Hypoxia and carbon dioxide rebreathing are potential problem s during eye surgery in spontaneously breathing patients. The aim of the pr esent study was to determine effectiveness of nasal application of oxygen t o prevent hypoxia and carbon dioxide accumulation in spontaneously breathin g patients undergoing cataract surgery. Methods-Oxygenation and carbon dioxide rebreathing were examined in 40 elde rly patients using two different methods of oxygen supply-nasal v ambient a ir-with a constant flow of 2 l/min. Partial pressure of carbon dioxide unde r ophthalmic drapes, transcutaneous pressure of carbon dioxide, and the res piratory rate were measured during 25 minutes while oxygen was supplied via a nasal cannula or into the ambient air under the drapes. Results-In both groups carbon dioxide accumulation under the drapes, carbon dioxide rebreathing, tachypnoea, and an increase in peripheral oxygen satu ration occurred. No significant differences were found between the two meth ods. Conclusion-Nasal application of oxygen prevented hypoxia but did not preven t carbon dioxide accumulation in patients undergoing eye surgery under retr obulbar anaesthesia. Additionally, as a side effect when using nasal probes , irritation of the nose was described in half of the patients investigated .