Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Jan 2008
Spirometric and anthropometric determinants of forced expiratory time in a general population.
Forced expiratory time (FET) has gained new interest in the joint recommendation of the American Thoracic Society (ATS) and the European Respiratory Society (ERS) for the assessment of spirometry. Interpretation of FET is, however, difficult as limited information is available on spirometric and anthropometric determinants of FET in populations. ⋯ The findings indicate that mean FET is around 11 s in a non-selected adult population and around 10 s in healthy non-smokers. FET increases slightly with age and BMI, suggesting age- and weight-related changes in pulmonary mechanics. The negative correlation of FET with FEV1/FVC and MMEF even in healthy non-smokers indicates that airflow limitation, either pathological or physiological, tends to prolong FET.
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Clin Physiol Funct Imaging · Jan 2008
Effect of graded leg cycling on postischaemic forearm blood flow in healthy subjects.
This study assessed in healthy subjects, the effect of leg cycling on the forearm vascular responses to ischaemia to confirm previous results showing that exercise-induced sympathetic activation during leg cycling reduced postischaemic forearm hyperaemia. Seven young healthy subjects performed two bouts of cycling exercises at 50% and 80% of their maximal aerobic capacity (Ex(50), Ex(80) respectively) during which forearm arterial blood flow was successively occluded for 40, 90 and 180 s. Control forearm blood flow (FBF) and postischaemic forearm blood flow (pi-FBF) measured at the release of arterial occlusions were assessed using plethysmography. ⋯ During Ex(80), there was a further dramatic decrease in pi-FC (-53%, -66%, -62% from rest) and pi-FBF were largely blunted (13 +/- 4 versus 19 +/- 3, 14 +/- 4 versus 29 +/- 3, 17 +/- 5 versus 31 +/- 4 ml min(-1) 100 ml(-1)). These results demonstrated that forearm responses to ischaemia depended on leg activities. It was suggested that exercise-induced sympathetic activation may have interfered on local vasodilatation because of ischaemia.
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Clin Physiol Funct Imaging · Jan 2008
Case ReportsObjective analysis of whole lung and lobar ventilation/perfusion relationships in pulmonary embolism.
Lung scintigraphy using single photon emission computed tomography (SPECT) allows accurate regional measurement of the ventilation/perfusion (V/Q) relationship. Objective V/Q analysis has been shown to be useful in the diagnosis of pulmonary embolism (PE). By using anatomical information provided by co-registered computed tomography, we describe methodology for determining the extent of V/Q heterogeneity at a lobar level. We investigate this methodology using simulated data, and demonstrate its potential application in the clinical setting of PE. ⋯ Segmentation and analysis of SPECT ventilation-perfusion scintigraphy at a lobar level can be used to quantify regional V/Q relationships. This objective methodology is sensitive to the presence of PE, and may be useful in a clinical setting.
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Clin Physiol Funct Imaging · May 2007
Could hyperoxic ventilation impair oxygen delivery in septic patients?
In critically ill patients, a decrease in whole body oxygen consumption under hyperoxia has been reported and this could be related to hyperoxia-induced arterial changes. We investigated changes in brachial artery circulation and tone during short-term hyperoxic ventilation in septic patients. ⋯ Hyperoxia was paradoxically demonstrated to decrease oxygen delivery in upper limbs during septic shock.
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Clin Physiol Funct Imaging · Mar 2007
ReviewLung protective ventilatory strategies in acute lung injury and acute respiratory distress syndrome: from experimental findings to clinical application.
This review addresses the physiological background and the current status of evidence regarding ventilator-induced lung injury and lung protective strategies. Lung protective ventilatory strategies have been shown to reduce mortality from adult respiratory distress syndrome (ARDS). ⋯ We describe a rational strategy, the open lung strategy, to accomplish an open lung, which may further prevent injury caused by mechanical ventilation. Finally, the clinician is offered directions on lung protective ventilation in the early phase of ARDS which can be applied on the intensive care unit.