Clinical physiology and functional imaging
-
Clin Physiol Funct Imaging · May 2017
The impact of venous occlusion per se on forearm muscle blood flow: implications for the near-infrared spectroscopy venous occlusion technique.
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. ⋯ 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.
-
Clin Physiol Funct Imaging · May 2017
Fixed ratio or lower limit of normal for the FEV1 /VC ratio: relation to symptoms and extended lung function tests.
There is no general agreement on the spirometric definition of chronic obstructive pulmonary disease (COPD). The global initiative for obstructive lung disease recommends a fixed ratio between forced expiratory volume in one-second (FEV1 ) and forced vital capacity (FVC) of <0·7 (FR) for the diagnosis of COPD. European Respiratory Society and American Thoracic Society favour the use of the fifth percentile of the age-related FEV1 /FVC ratio (the lower limit of normal, LLN). ⋯ For IOS, variables and symptoms increasingly abnormal values were seen from never smokers to FR+LLN+. This study shows that subjects meeting both spirometric COPD criteria frequently have symptoms and findings at extended lung function tests compatible with the diagnosis. Also subjects meeting the fixed ratio criterion only tend to have more symptoms and lung function findings compatible with COPD than ever-smoking subjects with FEV1 /VC > 0·7.