Abdul Hameed Bhatti.
Cataract surgery; effects of spontaneous versus controlled ventilation on intraocular pressure during General Anesthesia.
Professional Med J Jan ;15(1):114-9.

Objective: To compare the effects of spontaneous versus controlled ventilation on Intraocular Pressure (10P) with concomitant haemodynamic changes during cataract extraction and intraocular (IOL) implant surgery under anaesthesia. Design: Comparative study. Place and Duration of Study: The study was conducted at department of Anesthesiology Combined Military Hospital Jhelum Cantt from Jan 2005 to Oct 2005. Subjects and Methods: 40 ASA I and II patients of both sexes aged 40-68 years, undergoing surgical cataract extraction were studies. In 20 patients ventilation was controlled while the other 20 patients breathed spontaneously during surgery. 10P was measured preoperatively in non-operated eye. Results: Intraocular pressure (10P) decreased below the base line after induction of anaesthesia but it markedly increased after intubation in both group. During operation 10P decreased more in controlled ventilation group than spontaneous ventilation group. At the end of surgery before extubation, 10P increased in both groups with a greater rise in spontaneous ventilation group and extubation was followed by a further rise in 10P in both groups. Heart rate (HR) and arterial blood pressure (BP) changes followed almost the same pattern as 10P. Conclusion: General anaesthetics decrease 10P in general. Laryngoscopy and intubation are anaesthesia-related events, which cause rise in 10P. In appropriate patients, general anaesthesia with controlled ventilation is an acceptable technique for intraocular surgery offering advantages in terms of intraocular pressure and cardiovascular stability compared to spontaneous ventilation.

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