European journal of applied physiology
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Eur. J. Appl. Physiol. · Jun 2004
Clinical Trial Controlled Clinical TrialDeterminants of pulmonary perfusion measured by electrical impedance tomography.
Electrical impedance tomography (EIT) is a non-invasive imaging technique for detecting blood volume changes that can visualize pulmonary perfusion. The two studies reported here tested the hypothesis that the size of the pulmonary microvascular bed, rather than stroke volume (SV), determines the EIT signal. In the first study, the impedance changes relating to the maximal pulmonary pulsatile blood volume during systole (Delta Z(sys)) were measured in ten healthy subjects, ten patients diagnosed with chronic obstructive pulmonary disease, who were considered to have a reduced pulmonary vascular bed, and ten heart failure patients with an assumed low cardiac output but with a normal lung parenchyma. ⋯ In the second study, including seven healthy volunteers, Delta Z(sys) was measured at rest and during exercise on a recumbent bicycle while SV was measured by means of magnetic resonance imaging. The Delta Z(sys) at rest was 352 (53)x10(-5 ) and 345 (112)x10(-5 )AU during exercise (P=NS), whereas SV increased from 83 (21) to 105 (34) ml (P<0.05). The EIT signal likely reflects the size of the pulmonary microvascular bed, since neither a low cardiac output nor a change in SV of the heart appear to influence EIT.
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Eur. J. Appl. Physiol. · Jun 2004
Clinical Trial Controlled Clinical TrialEMG recovery and ratings after back extensor fatigue in patients with lumbar disc herniation and healthy subjects.
This prospective study aimed to examine whether patients with lumbar disc herniation, before and after surgery, showed impaired recovery from fatigue measured with EMG and subjective ratings as compared to healthy subjects. Forty-three patients due for, and after, lumbar disc surgery and 60 healthy subjects were fatigued using a modified Sørensen's test. Recovery of back extensor muscles was assessed using electromyography and the Borg scale ratings at 1, 2, 3, and 5 minutes of recovery, and was further analyzed using an exponential time-dependence model. ⋯ Specific items related to standing and lifting were identified. The patients' recovery was impaired compared to the healthy subjects, as determined by use of the exponential time-dependence model. The combination of fatigue and recovery measures was reflected in the questionnaire scores and is therefore important for evaluating patients with lumbar disc herniation.