Abstract
A prospective randomized study was undertaken on elderly patients undergoing intraocular, predominantly cataract, surgery to compare the intraoperative, recovery and postoperative features associated with general anaesthesia employing either the spontaneous (SV) or controlled ventilation (IPPV) techniques of respiration using isoflurane, nitrous oxide and a constant FiO2 of 0.33. SV patients received isoflurane 0.97% (mean). IPPV patients were intubated with atracurium alone, and received isoflurane 0.60% (mean). Heart rates were lower intraoperatively with IPPV, and blood pressures were lower with SV. Intraocular pressure measurement identified three subgroups of patients within each respiratory group: a large subgroup (70% of SV, 64% of IPPV patients) with a high-normal initial mean intraocular pressure which fell intraoperatively; a small subgroup (25% of SV, 24% of IPPV patients) with a low normal initial mean intraocular pressure which rose intraoperatively and a small subgroup (5% of SV and 11% of IPPV patients) in whom the intraocular pressure remained unchanged. A satisfactory operative field was reported by surgeons in 87% of SV and in 86% of IPPV patients. SV patients had a lower mean end-operative SaO2 than IPPV patients (SV 95.0%; IPPV 96.7%), and were extubated sooner at the end of anaesthesia. In the recovery ward the times to awakening, vomiting incidences, analgesic usages and recovery times were similar, and patients were similarly restful. Postoperatively, the incidences of vomiting, headache, fever, sore throat and myalgia were similar, but SV patients required more analgesia for headache. We conclude that both techniques properly performed are similarly satisfactory for cataract surgery in elderly patients.