title: The impact of venous occlusion per se on forearm muscle blood flow: implications for the near-infrared spectroscopy venous occlusion technique.
abstract: The purpose of this study was to examine the effect of venous occlusion per se on forearm muscle blood flow, as determined by the near-infrared spectroscopy (NIRS) venous occlusion technique (NIRS-VOT). NIRS data were obtained from the flexor digitorum superficialis (FDS) muscle on the dominant arm of 16 young, ostensibly healthy participants (14 men and two women; 30 ± 6 year; 73 ± 7 kg). Participants completed a series of five venous occlusion trials while seated at rest, and a series of 12 venous occlusion trials during a reactive hyperaemia induced by 5 min of forearm arterial occlusion. The NIRS-VOT was used to assess FDS muscle blood flow (Q˙mus), beat-by-beat, over the first four cardiac beats during venous occlusions. Q˙mus was also reported as a cumulative value, wherein the first two, first three and first four cardiac beats were used to calculate muscle blood flow. We observed that Q˙mus was highest when calculated over the first cardiac beat during venous occlusions performed at rest and throughout reactive hyperaemia (P<0·05). Moreover, the inclusion of more than one cardiac beat in the calculation of Q˙mus underestimated muscle blood flows, irrespective of the prevailing level of arterial inflow. These findings support the idea that venous occlusion per se affects the measurement of Q˙mus via the NIRS-VOT. Accordingly, it is recommended that Q˙mus is determined over the first cardiac beat when using the NIRS-VOT to assess microvascular blood flow of human forearm muscles.
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Qld, Australia.|Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Troy J
authors.initials: TJ
authors.lastname: Cross
authors.affiliation: Menzies Health Institute Queensland, Griffith University, Gold Coast, Qld, Australia.
authors.forename: Surendran
authors.initials: S
authors.lastname: Sabapathy
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D001794:Blood Pressure; D005260:Female; D005542:Forearm; D006339:Heart Rate; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D008833:Microcirculation; D008955:Models, Cardiovascular; D018482:Muscle, Skeletal / Q000098:blood supply*; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D014111:Tourniquets; D014680:Veins / Q000502:physiology*; D055815:Young Adult
keywords: forearm; muscle blood flow; near-infrared spectroscopy; venous occlusion