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Abstract #9794 Published in IGR 5-3
The effect of simulated obstructive apnoea on intraocular pressure and pulsatile ocular blood flow in healthy young adults
Lundmark PO; Trope GE; Flanagan JGBritish Journal of Ophthalmology 2003; 87: 1363-1369
AIM: To investigate the effect of negative inspiratory effort, as generated by the Mueller maneuver, on intraocular pressure (IOP) and pulsatile ocular blood flow (POBF) in healthy young adults. METHODS: Seven volunteers with no history of systemic or ocular disease were recruited (mean age 30.7 years, range 25-40 years, M/F: 4/3). After initial instruction and practice of the Mueller maneuver, baseline measurements of IOP and POBF were obtained for both eyes after ten and 15 minutes of rest, respectively, in the supine position. Thereafter, the Mueller maneuver was performed creating a mouthpiece pressure of -20 cm H2O, for at least 15 seconds followed by a five-minute rest. The maneuver was repeated with a mouthpiece pressure of -40 cm H2O. IOP and POBF were measured five to 15 seconds into the maneuver for both -20 cm H2O (M2A) and -40 cm H2O (M4A) and directly upon recovery (after two respiratory cycles) from each maneuver (M2B, M4B). Baseline measurements were compared using paired t test, whereas maneuver induced changes in IOP and POBF were analyzed individually using repeated measures ANOVA with Student-Newman Keuls post hoc analyses. Linear regression analysis was used to investigate a dose-response effect. RESULTS: No significant differences were found between baseline measurements, so they were subsequently pooled. There was a significant decrease in IOP for M2B (-9.2%, p < 0.05), M4A (-13.8%, p < 0.05), and M4B (-15.6%, p < 0.05), relative to baseline. A dose-response relationship was found for the effect of mouthpiece pressure on measurements five to ten seconds into the maneuver (M2A and M4A, r = 0.54, p = 0.045). There was a trend of increased POBF relative to baseline for all measurements; however, significance was reached for M4B only (p = 0.039). CONCLUSION: It was shown that forced inspiratory efforts as generated by the Mueller maneuver are associated with a dose dependent decrease in IOP and a concomitant increase in pulsatile ocular blood flow.
Dr. P.O. Lundmark, Department of Ophthalmology and Vision Sciences, Toronto Western Hospital, East Wing 6-503 399, Bathurst Street, Toronto, ON M5T 2S8, Canada
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
