Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 2015
Observational StudyReliability of a new 4th generation FloTrac algorithm to track cardiac output changes in patients receiving phenylephrine.
Phenylephrine is often used to treat intra-operative hypotension. Previous studies have shown that the FloTrac cardiac monitor may overestimate cardiac output (CO) changes following phenylephrine administration. A new algorithm (4th generation) has been developed to improve performance in this setting. ⋯ Agreement between FloTrac G3 and Nexfin was: 0.23 ± 1.19 l/min and concordance was 51.1%. In contrast, agreement between FloTrac G4 and Nexfin was: 0.19 ± 0.86 l/min and concordance was 87.2%. In conclusion, the pulse contour method of measuring CO, as implemented in FloTrac 4th generation algorithm, has significantly improved its ability to track the changes in CO induced by phenylephrine.
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J Clin Monit Comput · Aug 2015
Randomized Controlled TrialTranscutaneous continuous carbon dioxide tension monitoring reduced incidence, degree and duration of hypercapnia during combined regional anaesthesia and monitored anaesthesia care in shoulder surgery patients.
We studied the impact of transcutaneous continuous carbon dioxide tension (PtcCO2) monitoring on ventilation and oxygenation during monitored anaesthesia care (MAC) in patients scheduled for shoulder surgery with continuous interscalene block. 50 patients were randomised either to the intervention (I-group) or the control (C-group) group. In both groups MAC was performed using target controlled infusion of propofol and remifentanil. MAC regimen was adapted to PtcCO2 values in the I-group, whereas the C-group was blinded for these values. ⋯ Sensitivity and specificity of PtcCO2 to detect changes of PaCO2 was 0.94 and 0.56, respectively. In no patient SpO2 or SaO2 values lower than 90% were measured. Despite a moderate agreement between PaCO2 and PtcCO2 the PtcCO2 monitoring significantly reduced incidence, degree and duration of hypercapnia in shoulder surgery patients with MAC.
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J Clin Monit Comput · Aug 2015
Effect of concurrent oxygen therapy on accuracy of forecasting imminent postoperative desaturation.
Episodic postoperative desaturation occurs predominantly from respiratory depression or airway obstruction. Monitor display of desaturation is typically delayed by over 30 s after these dynamic inciting events, due to perfusion delays, signal capture and averaging. Prediction of imminent critical desaturation could aid development of dynamic high-fidelity response systems that reduce or prevent the inciting event from occurring. ⋯ In conclusion, we report the use of autoregressive models to predict [Formula: see text] and forecast imminent critical desaturation events in the postoperative period with high degree of accuracy. These models reliably predict critical desaturation in patients receiving supplemental oxygen therapy. While high-fidelity prophylactic interventions that could modify these inciting events are in development, our current study offers proof of concept that the afferent limb of such a system can be modeled with a high degree of accuracy.
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J Clin Monit Comput · Aug 2015
Pulse transit time shows vascular changes caused by propofol in children.
Pulse transit time (PTT) is the time that it takes for the arterial pulse pressure wave to travel from the aortic valve to the periphery. It is a simple noninvasive technique for evaluating vascular changes. This study investigated the vascular changes by propofol during the induction of anesthesia in pediatric patients with the measuring of PTT. ⋯ The PTT after the peak changed variously; most of the patients showed no plateau; the PTT decreased progressively after the peak. The PTT after propofol administration prolonged in short time and rapidly recovered toward to the baseline values in pediatric patients. In conclusion, the baseline PTT in children is shorter comparing with adults and the vasodilatory effect of propofol on the vessels as described by the PTT was rapid and the recovery was faster, although the response to propofol was more varied than in adults.
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J Clin Monit Comput · Aug 2015
Cutaneous mitochondrial respirometry: non-invasive monitoring of mitochondrial function.
The recently developed technique for measuring cutaneous mitochondrial oxygen tension (mitoPO2) by means of the Protoporphyrin IX-Triplet State Lifetime Technique (PpIX-TSLT) provides new opportunities for assessing mitochondrial function in vivo. The aims of this work were to study whether cutaneous mitochondrial measurements reflect mitochondrial status in other parts of the body and to demonstrate the feasibility of the technique for potential clinical use. The first part of this paper demonstrates a correlation between alterations in mitochondrial parameters in skin and other tissues during endotoxemia. ⋯ A first prototype of a clinical PpIX-TSLT monitor is described and its usability is demonstrated on human skin. We expect that clinical implementation of this device will greatly contribute to our understanding of mitochondrial oxygenation and oxygen metabolism in perioperative medicine and in critical illness. Our ultimate goal is to develop a clinical monitor for mitochondrial function and the current results are an important step forward.