Normocapnic anaesthesia for intraocular surgery.

Measurement of intraocular pressure (IOP) by applanation tonometry in 23 patients undergoing lens extraction showed that a normocapnic general anaesthetic technique with controlled ventilation of the lungs (IPPV) reliably reduced the IOP by 50% for the duration of the operative period. This was not associated with large falls in systemic arterial pressure which are often a feature of spontaneously breathing halothane anaesthesia for eye surgery. Normocapnia and IPPV were easy to achieve by use of the single-limb coaxial Bain anaesthetic breathing circuit in conjunction with an electrically driven, small, and inexpensive ventilator while the anesthetic mixture of 33% oxygen and 0.5% halothane in nitrous oxide was delivered at a rate of 70 ml/kg body weight per minute.