Retinal tissue oxygen tension in normoxic cats under enflurane anesthesia

Kimberly Neely, J. T. Ernest, T. K. Goldstick

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Purpose. General anesthesia reduces systemic blood pressure and, thus, ocular perfusion pressure (at constant intraocular pressure). Whether this reduction in ocular perfusion pressure produces retinal hypoxia is unknown. To answer this question, the authors measured inner retinal oxygen tension in cats under general enflurane anesthesia at three clinically relevant levels of anesthesia under normoxic conditions. Methods. Polarographic oxygen microelectrodes were used to measure inner retinal oxygen tension in cats under enflurane anesthesia at 21% inspired oxygen tension. Measurements were made in the preretinal vitreous body within 100 to 200 μm of the internal limiting membrane of the retina. Three levels of enflurane anesthesia were used: 1.2%, 2.4%, and 3.6%, corresponding to 0.5, 1.0, and 1.5 minimal alveolar concentration. Intraocular pressure of the cats was maintained at a constant normal level throughout the experiments. Results. Under normoxic conditions, inner retinal oxygen tension remained unchanged or increased slightly as ocular perfusion pressure decreased with deeper levels of enflurane anesthesia. Conclusion. Commonly used surgical levels of enflurane general anesthesia do not cause hypoxia of the inner retina in cats breathing 21% inspired oxygen. This may be the result of preservation of retinal vascular autoregulation under enflurane anesthesia, retinal vasodilatation secondary to a direct smooth muscle relaxing effect of enflurane, or decreased retinal oxygen use under enflurane anesthesia.

Original languageEnglish (US)
Pages (from-to)1943-1946
Number of pages4
JournalInvestigative Ophthalmology and Visual Science
Volume36
Issue number9
StatePublished - 1995

All Science Journal Classification (ASJC) codes

  • Ophthalmology

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