Department of Anaesthesia, Royal Liverpool University Hospital, Prescot Street, Liverpool L7 8XP, UK 1Present address: Department of Anaesthesia, Dandenong Hospital, Southern Health Care Network, Dandenong, Victoria 3175, Australia*Corresponding author
Accepted for publication: April 10, 2001
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Abstract |
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Br J Anaesth 2001; 87: 62931
Keywords: eye, intra-ocular pressure; vomiting, antiemetics, ondansetron
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Introduction |
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Ondansetron is a commonly used antiemetic drug with few side-effects.1 It has a proven efficacy to prevent and treat postoperative nausea and vomiting in non-ophthalmic and ophthalmic surgery.2 3 However, its effects on IOP are unknown. Consequently, this study was undertaken to ascertain the effects of i.v. ondansetron on IOP.
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Methods and results |
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Patients under 18 yr of age, ASA class IV or V, who vomited or received antiemetics before surgery were excluded. Those with a history of substance abuse, glaucoma, those who were pregnant or breast-feeding or had a contraindication to the use of ondansetron were also excluded.
IOP was measured using a calibrated Keeler pulsair 2000 non-contact applanation tonometer (Keeler Plc, UK). It is a simple instrument to use with an accuracy of ±1 mm Hg.5 IOP measurements were obtained from the eye not undergoing surgery. Baseline IOP, arterial pressure (AP) and heart rate (HR) were measured. Ondansetron 4 mg or 0.9% saline as 2 ml solution was administered intravenously. Five minutes later, IOP, AP, and HR were measured. Anaesthesia and muscle relaxation were achieved with thiopentone 25 mg kg1 and atracurium 0.5 mg kg1. Patients lungs were ventilated to normocapnia with 35% oxygen in nitrous oxide and 1% isoflurane. Further IOP, AP, and HR were measured immediately before, immediately following and 5 min after intubation.
After the study period, droperidol 0.02 mg kg1 was given and a rescue antiemetic was prescribed postoperatively. After surgery, muscle relaxation was reversed with glycopyrrolate and neostigmine.
Homogeneity of variance was established using Levenes test and the data were compared using Students t and chi-squared tests according to variables. Within group analysis was performed with ANOVA with Bonferronis correction. P-value <0.05 was considered significant.
There were no significant differences between the ondansetron and the saline groups in terms of age, gender, mean baseline IOP, and systolic AP (SAP) (Table 1). Baseline HR and diastolic AP (DAP) were significantly lower in the ondansetron group than the saline group (P<0.05).
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Comments |
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The purpose of this study was to ascertain the effects of ondansetron on IOP, not to assess its efficacy as an antiemetic, which has been reported previously.1 2 Ondansetron was associated with cardiovascular stability6 and no effect on intra-cranial or cerebral perfusion pressures7 and, therefore, unlikely to affect IOP. This study confirms that ondansetron does not increase IOP before, or during, induction of anaesthesia for ophthalmic surgery. These findings contrast with other antiemetics used in ophthalmic anaesthesia, which are associated with side effects. Metoclopramide may increase IOP8 and droperidol causes hypotension, postoperative drowsiness and confusion in elderly patients.9 The former agent should not be given before induction of anaesthesia in patients with perforating eye injuries, as it may lead to loss of intraocular contents. The latter should be used cautiously in aged patients.
In conclusion, IOP appears to be stable following i.v. administration of ondansetron before induction of anaesthesia. We suggest that ondansetron can be safely given before induction for the prevention or the treatment of nausea and vomiting in patients in whom it is essential to minimize changes in IOP such as those with perforating eye injuries or glaucoma.
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Acknowledgements |
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References |
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