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How does sevoflurane induction, followed by a ketamine maintenance infusion, affect intraocular pressure? Establishment of an anaesthetic protocol for paediatric glaucoma examinations under anaesthesia
  1. Jessica Gwendoline van der Walt1,2,
  2. Francois Roodt3,4,5,
  3. Christopher Tinley5,6
  1. 1Department of Anaesthesia, University of Cape Town, Cape Town, South Africa
  2. 2Department of Anaesthesia, Victoria Hospital, Cape Town, South Africa
  3. 3Department of Anaesthesia and Perioperative Medicine, University of Cape Town, Cape Town, South Africa
  4. 4Department of Anaesthesia, Groote Schuur Hospital, Cape Town, South Africa
  5. 5Red Cross War Memorial Children’s Hospital, Cape Town, South Africa
  6. 6Department of Ophthalmology, University of Cape Town, Cape Town, Western Cape, South Africa
  1. Correspondence to Dr Jessica Gwendoline van der Walt, 6 Bridgeleap Road, Downend, Bristol, BS16 6TE; jessicagwendoline{at}hotmail.com

Abstract

Accurate measurement of intraocular pressure (IOP) is essential in paediatric glaucoma management. Children require serial measurements and examination under anaesthesia (EUA). Most anaesthetic agents reduce IOP, and the ideal time to measure IOP under anaesthesia is questionable.

Study purpose To determine the effect of sevoflurane induction, followed by intravenous ketamine infusion on IOP, in children undergoing EUA for glaucoma or suspected glaucoma, and to establish the earliest time point at which reliable, repeatable IOP measurements can be obtained under anaesthesia.

Method A prospective, descriptive study of IOP changes occurring in children requiring EUAs. A standardised anaesthetic protocol: sevoflurane induction, intravenous cannulation, 2 mg/kg intravenous ketamine bolus and 4 mg/kg/hour maintenance for 15 min. IOP measurements (taken supine with a Perkins applanation tonometer) and physiological variables were recorded.

Results IOPs were measured in 25 children (50 eyes). Twenty-six eyes (52%) were glaucomatous. Mean patient age was 29 months (2–88 months). Physiological variables returned to baseline at 8 min, correlating with recorded sevoflurane elimination. Mean IOP after sevoflurane induction was 3.68 mm Hg lower than with ketamine maintenance at 15 min (95% CI 1.35 to 6.02 mm Hg) (p=0.002). Contrastingly, the difference in IOP between ketamine anaesthesia at 15 min and near wakefulness was 0.28 mm Hg (95% CI −2.23 to 2.79 mm Hg) (p=0.826).

Conclusion Sevoflurane’s IOP-lowering effect is reversed 15 min after the discontinuation of the inhalational gas, if anaesthesia is maintained with an intravenous ketamine infusion. IOP measurements appear to stabilise at this time point until the point of near wakefulness and may reflect awake values.

  • intraocular pressure
  • glaucoma
  • child health (paediatrics)
  • pharmacology

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Footnotes

  • Ophthalmology Society of South Africa Annual Congress 2016 South African Society of Anaesthetists Annual Congress 2017

  • Contributors All investigators participated actively in the planning and execution of this study. This included patient recruitment and consent, performance of anaesthesia and study technique, data capture and assessment. FR: principal investigator. CT: all IOP measurements. JGvdW wrote this manuscript and literature review.

  • Funding Statistical analyses were funded from departmental resources.

  • Competing interests None declared.

  • Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.

  • Ethics approval University of Cape Town Human Research Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement No additional data are available.

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