Journal of clinical monitoring and computing
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J Clin Monit Comput · Oct 2011
Clinical TrialMonitoring of breathing phases using a bioacoustic method in healthy awake subjects.
To test the ability of a microphone recording system, located distal to the respiratory outflow tract, to track the timing of the inspiratory and expiratory phases of breathing in awake healthy subjects. ⋯ Frequency spectra of breathing sounds recorded from a face-frame, reliably identified the inspiratory and expiratory phases of breathing. This technique may have various applications for respiratory monitoring and analysis.
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J Clin Monit Comput · Oct 2011
Comparative StudyComparison of ear and chest probes in transcutaneous carbon dioxide pressure measurements during general anesthesia in adults.
For transcutaneous carbon dioxide pressure (tcPCO(2)) measurement, the probe on the trunk or extremities has been used for many years. Our previous study showed that chest was better than arm for tcPCO(2) monitoring. Recently, the ear probe has been developed. The accuracy of tcPCO(2) as a surrogate measurement of arterial carbon dioxide pressure (PaCO(2)) has not been compared between the measurement with probe on the chest and measurement with probe on the earlobe. This study compared the accuracy of tcPCO(2) measured on the chest and tcPCO(2) measured on earlobe during general anesthesia in adults using linear regression analysis and Bland-Altman plot. ⋯ During general anesthesia in adults, both TtcPCO(2) and StcPCO(2) were not interchangeable with PaCO(2), but only TtcPCO(2) had good positive correlation with PaCO(2).
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J Clin Monit Comput · Aug 2011
Case ReportsDecrease in pulmonary artery pressure after administration of thoracic epidural anesthesia in a patient with Marfan syndrome awaiting aortic valve replacement procedure.
Thoracic epidural anesthesia is an adjunct to general anesthesia in cardiac surgery. Decrease in heart rate and blood pressure are frequently seen beneficial effects. There are several other hemodynamic effects of thoracic epidural anesthesia such as decrease in systemic vascular resistance, cardiac index, left ventricular stroke work index among others. ⋯ The authors present this case to generate discussion about the possible mechanisms involved in thoracic epidural anesthesia producing beneficial effects in patients with secondary pulmonary hypertension. Thoracic epidural anesthesia appears to decrease pulmonary artery pressure by a combination of several mechanisms, some unknown to us. This occurrence, if studied and understood well could be put to clinical use in pulmonary hypertensives.
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J Clin Monit Comput · Aug 2011
Pharmacodynamic modeling of propofol-induced tidal volume depression in children.
This investigation aimed to develop a pediatric pharmacodynamic model of propofol-induced tidal volume depression towards an ultimate goal of developing a dosing schedule that would preserve spontaneous breathing following a loading dose of propofol. ⋯ A pediatric pharmacodynamic model of propofol-induced tidal volume depression was developed. Models derived from 3 different approaches were shown to be consistent with each other; however, the individual pharmacodynamic parameters exhibited significant inter-individual variability without strong dependence on age and body weight. This would suggest the desirability of adapting the pharmacodynamic model to each subject in real time.
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The pleth variability index (PVI), which is calculated from respiratory variations in the perfusion index (PI), reportedly predicts fluid responsiveness. However, vasomotor tone fluctuations induced by nociceptive stimuli change the PI and may reduce the accuracy of PVI. The aim of this study was to confirm the effects of surgical stimuli on PVI. ⋯ This study showed a significant increase in the PVI and a negative correlation between the changes in PVI and PI before and after the skin incision. The PVI can be calculated from the variations in the PI caused not by mechanical ventilation, but rather by fluctuations in vasomotor tone. When using the PVI as an indicator for fluid responsiveness, it is crucial to pay attention to fluctuations in vasomotor tone induced by nociceptive stimuli.