SILENT-MYOCARDIAL-ISCHEMIA IN CONNECTION WITH CATARACT-SURGERY - EFFECT OF PROPHYLACTIC OXYGENATION

Objectives To examine whether elderly patients having cataract extract ion under regional anaesthesia present with silent myocardial ischaemi a, and to seek an association with possible decreases in arterial oxyg en saturation (SpO(2)). Methods We used Hotter monitoring in 33 patien ts, 14 with and 19 without evidence of ischaemic heart disease (IHD). Patients were allocated randomly to groups to receive oxygen beginning before retrobulbar block (n = 17) or surgery (n = 16). SpO(2), haemod ynamic changes and anxiety were noted in relation to possible ischaemi c events. Results During and after retrobulbar block, and at the begin ning of cataract surgery, (usually brief) ischaemia detected by ST-seg ment depression was present both in patients with IHD (three out of 14 ) and in those free from clinical symptoms of IHD (three out of 19). T he occurrence of ST-segment depression was not statistically related t o small haemodynamic changes, but was related to foregoing or simultan eous decreases in SpO(2). Nasal administration of oxygen created a 2-5 % margin of safety with regard to minimum detected SpO(2). Conclusions For patients with IHD, we recommend prophylactic administration of ox ygen, beginning a minimum of 5 min before the regional block and conti nuing until the completion of surgery.