eprintid: 2473 rev_number: 10 eprint_status: archive userid: 151 dir: disk0/00/00/24/73 datestamp: 2007-03-14 12:00:00 lastmod: 2015-07-23 09:33:23 status_changed: 2008-01-09 13:38:51 type: article metadata_visibility: show creators_name: Tachtsidis, I. creators_name: Tisdall, M. creators_name: Leung, T.S. creators_name: Cooper, C.E. creators_name: Delpy, D.T. creators_name: Smith, M. creators_name: Elwell, C.E. creators_id: ITACH19 creators_id: MMTIS18 creators_id: TSTLE21 creators_id: CECOO61 creators_id: creators_id: MSMIT43 creators_id: CEELW72 title: Investigation of in vivo measurement of cerebral cytochrome-c-oxidase redox changes using near-infrared spectroscopy in patients with orthostatic hypotension ispublished: pub subjects: 8400 subjects: 25600 divisions: F42 divisions: F82 keywords: near-infrared spectroscopy, cytochrome c oxidase, cerebral oxygenation, autonomic failure abstract: We have previously used a continuous four wavelength near infrared spectrometer to measure changes in the cerebral concentrations of oxy- (Δ[HbO2] and deoxy- haemoglobin (Δ[HHb]) during head-up tilt in patients with primary autonomic failure. The measured changes in light attenuation also allow calculation of changes in the concentration of oxidised cytochrome c oxidase (Δ[oxCCO]), and this paper analyses the Δ[oxCCO] during the severe episodes of orthostatic hypotension produced by this experimental protocol. We studied 12 patients during a passive change in position from supine to a 60º head-up tilt. The challenge caused a reduction in mean blood pressure of 59.93 (±26.12) mmHg (Mean (±SD), p<0.0001), which was associated with a reduction in the total concentration of haemoglobin (Δ[HbT]= Δ[HbO2]+Δ[HHb]) of 5.02 (±3.81) μM (p<0.0001) and a reduction in the haemoglobin difference concentration (Δ[Hbdiff]= Δ[HbO2]-Δ[HHb]) of 14.4 (±6.73) μM (p<0.0001). We observed a wide range of responses in Δ[oxCCO]. 6 patients demonstrated a drop in Δ[oxCCO] (0.17 ±0.15μM ); 4 patients demonstrated no change (0.01 ±0.12 μM ) and 2 patients showed an increase in Δ[oxCCO] (0.21 ±0.01 μM ). Investigation of the association between the changes in concentrations of haemoglobin species and the Δ[oxCCO] for each patient show a range of relationships. This suggests that a simple mechanism for crosstalk, which might produce artefactual changes in [oxCCO], is not present between the haemoglobin and the oxCCO NIRS signals. Further investigation is required to determine the clinical significance of the changes in [oxCCO]. date: 2007 date_type: published official_url: http://dx.doi.org/10.1088/0967-3334/28/2/008 vfaculties: VENG vfaculties: VFBRS rae2008: 19 oa_status: green language: eng primo: open primo_central: open_green doi: 10.1088/0967-3334/28/2/008 lyricists_name: Tachtsidis, I lyricists_name: Tisdall, M lyricists_name: Leung, T lyricists_name: Cooper, C lyricists_id: ITACH19 lyricists_id: MMTIS18 lyricists_id: TSTLE21 lyricists_id: CECOO61 full_text_status: public publication: Physiological Measurement volume: 28 number: 2 pagerange: 198-211 refereed: TRUE issn: 0967-3334 citation: Tachtsidis, I.; Tisdall, M.; Leung, T.S.; Cooper, C.E.; Delpy, D.T.; Smith, M.; Elwell, C.E.; (2007) Investigation of in vivo measurement of cerebral cytochrome-c-oxidase redox changes using near-infrared spectroscopy in patients with orthostatic hypotension. Physiological Measurement , 28 (2) pp. 198-211. 10.1088/0967-3334/28/2/008 <https://doi.org/10.1088/0967-3334%2F28%2F2%2F008>. Green open access document_url: https://discovery-pp.ucl.ac.uk/id/eprint/2473/1/2473.pdf