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Lisa A Hethcox, Chester Calvert, Christopher A Girkin, J Crawford C Downs; The Effects of General Anesthesia on IOP in Nonhuman Primates (NHP). Invest. Ophthalmol. Vis. Sci. 2014;55(13):123.
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To assess the effects of both injectable and inhalant anesthesia on IOP.
We have developed and validated an implantable telemetry system that wirelessly records 500 measurements of IOP per second for up to 2-1/2 years (IOVS 52(10):7365-75). Using an enhanced version of this system, continuous bilateral IOP, bilateral electro-oculogram (EOG), and aortic blood pressure were recorded both before and after anesthetic induction and maintenance in two different sessions, 2 weeks apart in 3 young adult male rhesus macaques aged 3-6 years old. The IOP transducers were calibrated via anterior chamber manometry, and all data corrected for signal drift. Bilateral IOP was quantified before and after anesthetic induction with Ketamine (3mg/kg) and Dexdomitor (50mg/kg), and again after Isoflurane inhalant had stabilized the anesthetic plane (2-5% induction, 0.5-2% maintenance), and compared to baseline IOP prior to anesthesia.
The Table shows that both anesthetic induction with IM injectables and anesthesia maintenance with isoflurane gas can affect IOP compared to baseline, but the effects were specific for each animal and was not consistent between sessions. Overall, IOP was only slightly lower overall (0.4 mmHg) after the NHP had reached a stable anesthetic plane of isoflurane gas compared to pre-anesthesia baseline IOP, although IOP effects were much higher in individual animals/sessions. Note that the changes shown after anesthetic induction are largely due to the lateral recumbent position and not anesthesia.
General anesthesia is common in both animal studies and human patient procedures, but its effects on IOP are largely unknown. Results show that the IOP are individual and session specific, and can reach 4 mmHg at times. This should be taken into account when consideration of IOP or its effects is important.
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