Clinical physiology and functional imaging
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Clin Physiol Funct Imaging · Jan 2007
Clinical TrialCO2 elimination at varying inspiratory pause in acute lung injury.
Previous studies have indicated that, during mechanical ventilation, an inspiratory pause enhances gas exchange. This has been attributed to prolonged time during which fresh gas of the tidal volume is present in the respiratory zone and is available for distribution in the lung periphery. The mean distribution time of inspired gas (MDT) is the mean time during which fractions of fresh gas are present in the respiratory zone. ⋯ The change in V(T)CO(2) reflected to equal extent changes in airway dead space and alveolar PCO(2) read from the alveolar plateau of the single breath test for CO(2). By varying T(P), effects are observed on V(T)CO(2), airway dead space and alveolar PCO(2). These effects depend on perfusion, gas distribution and diffusion in the lung periphery, which need to be further elucidated.
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Clin Physiol Funct Imaging · Nov 2006
Case ReportsEarly recovery from post-traumatic acute respiratory distress syndrome.
To present and discuss the rationale and possible benefits of timely alveolar recruitment in early post-traumatic acute respiratory distress syndrome. ⋯ Although robust evidence is still lacking, several lines of evidence suggest potential benefits of timely alveolar recruitment. Patients with early post-traumatic respiratory failure seem to most readily respond to alveolar recruitment manoeuvres and could thus benefit from the gain in functional lung volume and oxygenation. Moreover the probability of ventilator associated complications may be reduced.
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Clin Physiol Funct Imaging · Nov 2006
Supraorbital cutaneous blood flow rate during carotid endarterectomy.
The supraorbital skin region is supplied by the supraorbital artery, which is a branch of the internal carotid artery. The supraorbital cutaneous blood flow rate may therefore be influenced by changes in the internal carotid artery flow during carotid endarterectomy. ⋯ Cross-clamping of the internal carotid artery affects the supraorbital cutaneous blood flow rate as well as the frontal lobe oxygenation.
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Clin Physiol Funct Imaging · Sep 2006
The effects of unilateral transcutaneous electrical nerve stimulation of the median nerve on bilateral somatosensory thresholds.
Transcutaneous electrical nerve stimulation (TENS) is used to relieve acute and chronic pain. TENS electrodes are applied at the site of pain or in segments related to the pain, although there is limited research to support either approach. This study investigated the effects of unilateral TENS on mechanical and thermal thresholds at ipsilateral and contralateral sites in healthy human participants. ⋯ TENS effects had disappeared 30 min after TENS had been switched off although there was a tendency for thermal thresholds to remain elevated. We conclude that during stimulation, TENS elevates somatosensory thresholds within the distribution of the stimulated nerve. The rapid and short-lived ipsilateral effect is consistent with findings from animal studies and suggests a central segmental mechanism.
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Clin Physiol Funct Imaging · Jul 2006
Measurement of expired carbon dioxide, oxygen and volume in conjunction with pretest probability estimation as a method to diagnose and exclude pulmonary venous thromboembolism.
The classical alveolar pCO(2)-pO(2) relationship predicts that pulmonary embolism (PE) causes a low ratio of pCO(2)/pO(2) at end expiration. Our purpose was to define a simple protocol to collect expired pCO(2)/pO(2) to diagnose PE. Emergency department patients with suspected PE were enrolled. Clinical pretest probabilities for PE were estimated prior to diagnostic testing using the Canadian score and clinicians' unstructured estimate. Patients provided three 30-s periods of tidal breathing, separated by three deep exhalations. Expired pCO(2), pO(2) and breath volume were measured. All patients underwent standardized objective testing for PE including 90-day follow-up. Diagnosis (PE+) required anticoagulation for image-proven PE within 90 days. ⋯ This preliminary work demonstrates that the end-tidal pCO(2)/pO(2) averaged from 30 s of breathing can produce clinically relevant likelihood ratios for the diagnosis and exclusion of PE.