Journal of clinical monitoring and computing
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J Clin Monit Comput · Feb 2014
Randomized Controlled TrialUse of a decision support system improves the management of hemodynamic and respiratory events in orthopedic patients under propofol sedation and spinal analgesia: a randomized trial.
Decision support systems (DSSs) have been successfully implemented into clinical practice offering clinical suggestions and treatment options with excellent results in various clinical settings. Although their results appeared promising, showing that DSSs can increase anesthesiologists' vigilance and patient safety during surgery, DSSs have never been used before to help anesthesiologists in identifying critical events in patients under spinal analgesia with sedation. We have developed and clinically evaluated a DSS for this specific task. ⋯ The number of critical events/h occurring and the duration of surgery were similar in both groups. The number of hypoxemia episodes was significantly less (P = 0.036) in the DSS group (0.7 ± 1.0 vs. 1.4 ± 2.2 for the Control Group). The DSS tested in this trial could help the clinician to detect and treat critical events more efficiently and in a shorter length of time.
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J Clin Monit Comput · Feb 2014
Comparative StudyDetection of changes in muscle oxygen saturation in the human leg: a comparison of two near-infrared spectroscopy devices.
The purpose of this study was first to evaluate the near infrared spectroscopy (NIRS) device, INVOS 4100 as a method of measuring exercise and arterial occlusion induced muscle ischemia in human leg, by comparison with InSpectra tissue spectrometer Model 325, and secondly to determine the influence of skin and subcutaneous thickness on the NIRS measurements. Twenty healthy subjects (43 ± 8 years) volunteered for the study. Tissue oxygen saturation (StO2) in the anterior tibial muscle was measured simultaneously with InSpectra Model 325 in one leg and INVOS 4100 in the contralateral leg during an exercise test until muscle exhaustion and arterial occlusion with and without exercise. ⋯ There was a significant inverse correlation between skin and subcutaneous thickness and baseline StO2 (r = -0.78, p < 0.01) as well as change in StO2 during exercise (r = -0.65, p = 0.002) for InSpectra, which was not apparent for INVOS. The results demonstrate that the cerebral/somatic oxygenation monitor (INVOS) is able to detect experimentally induced skeletal muscle ischemia in the human leg as well as the peripheral tissue spectrometer (InSpectra). Muscle oxygen saturation measurement by INVOS is less affected by skin and subcutaneous thickness than measured by InSpectra.
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J Clin Monit Comput · Feb 2014
A pilot study quantifying the shape of tidal breathing waveforms using centroids in health and COPD.
During resting tidal breathing the shape of the expiratory airflow waveform differs with age and respiratory disease. While most studies quantifying these changes report time or volume specific metrics, few have concentrated on waveform shape or area parameters. The aim of this study was to derive and compare the centroid co-ordinates (the geometric centre) of inspiratory and expiratory flow-time and flow-volume waveforms collected from participants with or without COPD. ⋯ A comparison of airflow waveforms show that in COPD, the breathing rate is faster (17 ± 4 vs 14 ± 3 min(-1)) and the time to reach peak expiratory flow shorter (0.6 ± 0.2 and 1.0 ± 0.4 s). The expiratory flow-time and flow-volume centroid is left-shifted with the increasing asymmetry of the expired airflow pattern induced by airway obstruction. This study shows that the degree of skew in expiratory airflow waveforms can be quantified using centroids.
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Although feedback control and automation has revolutionized many fields of human activity, it has yet to have a significant impact on healthcare, particularly when a patient is in the loop. Although there have been a number of studies concerned with closed-loop control of anesthesia, they have yet to have an impact on clinical practice. ⋯ Concepts such as modelling for control, feedback and uncertainty, robustness, feedback controller such as proportional-integral-derivative control, predictive control and adaptive control are briefly reviewed. Finally we discuss the safety issues around closed-loop control and discuss ways by which safe control can be guaranteed.