Leicester Royal Infirmary

About: Leicester Royal Infirmary is a healthcare organization based out in Leicester, United Kingdom. It is known for research contribution in the topics: Population & Carotid endarterectomy. The organization has 5300 authors who have published 6204 publications receiving 208464 citations.

Multivariate dynamic analysis of cerebral blood flow regulation in humans

Abstract: The contributions of beat-to-beat changes in mean arterial blood pressure (MABP) and breath-by-breath fluctuations in end-tidal CO/sub 2/ (EtCO/sub 2/) as determinants of the spontaneous variability of cerebral blood flow velocity (CBFV) were studied in 16 normal subjects at rest. The two input variables (MABP and EtCO/sub 2/) had significant cross-correlations with CBFV but not between them. Transfer functions were estimated as the multivariate least mean square finite impulse response causal filters. MABP showed a very significant effect in explaining CBFV variability (p<10/sup -11/, Fisher's aggregated-p test) and the model mean square error was significantly reduced (p<0.001) by also including the contribution EtCO/sub 2/. The estimated mean CBFV step response to MABP displayed the characteristic return to baseline caused by the cerebral autoregulatory response. The corresponding response to EtCO/sub 2/ showed a gradual rise taking approximately 10 s to reach a plateau of 2.5%/mmHg. This study demonstrated that spontaneous fluctuations in EtCO/sub 2/ can help to explain the CBFV variability at rest if appropriate signal processing techniques are employed to address the limited power and bandwidth of the breath-by-breath EtCO/sub 2/ signal.

A randomized controlled trial of unilateral strabismic and mixed amblyopia using occlusion dose monitors to record compliance.

Abstract: Purpose To investigate compliance with patching therapy and the dose-effect relationship in occlusion therapy in amblyopia by recording the effective patching time using occlusion dose monitors (ODMs). Methods Fifty-two children with strabismic or mixed amblyopia (Snellen equivalent, 6/12-6/48) were given optimal refractive correction and randomly allocated for 12 weeks into three treatment groups: group 1, no patching; group 2, prescribed patching for 3 hours; and group 3, prescribed patching for 6 hours. The effective time of occlusion was monitored with ODMs continuously. Visual acuity (VA) was measured every 3 weeks with LogMAR (logarithm of the minimum angle of resolution) Crowded Tests. Results In the 3- and 6-hour groups, mean (SD) compliance was 57.5% (30.8%) and 41.2% (30.9%), respectively, and mean effective patching time per day was 1 hour 43 minutes (55 minutes) and 2 hours 33 minutes (1 hour 52 minutes), respectively. The mean (SD) improvement in logMAR VA of amblyopic eyes was 0.24 (0.17), 0.29 (0.14), and 0.34 (0.19) in groups 1, 2, and 3, respectively. There was no significant difference in compliance with the prescribed patching between the 3- and 6-hour groups. VA outcomes in the 3- and 6-hour groups were not significantly better than 0-hour patching. However, the VA of patients with eyes effectively patched for more than 3 hours improved significantly. A dose-effect relationship was observed. Age at treatment did not influence the visual outcome. Conclusions Poor compliance with prescribed occlusion explains discrepancies in previous studies. No differences in the effect between the different prescribed patching periods were found. The dose-effect relationship observed should encourage development of methods such as educational intervention to improve visual outcome by increasing effective patching time.