Journal of clinical monitoring and computing
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Passive leg raising (PLR) provides a reversible fluid-loading challenge and can be used to predict fluid responsiveness. The amount of blood volume recruited by this maneuver called stressed volume (Vs) is unknown. The present study aims to assess the quantitative effects of passive leg raising on venous return at bedside. ⋯ The effect of transient hemodynamic changes on venous return induced by passive leg raising can be directly measured in intensive care patients using inspiratory-hold procedures. This technique makes quantification of PLR feasible and could be used clinically to assess fluid responsiveness.
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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.
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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
The impact of induction of general anesthesia and a vascular occlusion test on tissue oxygen saturation derived parameters in high-risk surgical patients.
Tissue oxygen saturation (StO(2)) assessed using Near Infrared Spectroscopy and its derived parameters during a vascular occlusion test (VOT) can detect microvascular changes in septic shock patients. General anesthesia (GA) impacts microcirculation. Our aim was to study the effects of general anesthesia on StO(2) and StO(2) derived parameters obtained during VOT in patients referred for cardiac surgery. ⋯ StO(2) derived parameters during a VOT are impacted by GA induction. These parameters may have potential for microcirculation assessment in patients undergoing surgery.