Journal of clinical monitoring and computing
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J Clin Monit Comput · Oct 2013
Association of intraoperative tissue oxygenation with suspected risk factors for tissue hypoxia.
Tissue hypoxia may cause organ dysfunction, but not much is known about tissue oxygenation in the intraoperative setting. We studied microcirculatory tissue oxygen saturation (StO₂) to determine representative values for anesthetized patients undergoing urological surgery and to test the hypothesis that StO₂ is associated with known perioperative risk factors for morbidity and mortality, conventionally monitored variables, and hypotension requiring norepinephrine. Using near-infrared spectroscopy, we measured StO₂ on the thenar eminence in 160 patients undergoing open urological surgery under general anesthesia (FiO2 0.35-0.4), and calculated its correlations with age, risk level for general perioperative complications and mortality (high if age ≥70 and procedure is radical cystectomy), mean arterial pressure (MAP), hemoglobin concentration (Hb), central venous oxygen saturation (ScvO₂), and norepinephrine use. ⋯ Finally, StO₂ was slightly lower in patients requiring norepinephrine (85 ± 6 vs. 89 ± 6 %, p = 0.001). Intraoperative StO₂ in urological patients was comparable to that of healthy volunteers breathing room air as reported in the literature and correlated with known perioperative risk factors. Further research should investigate its association with outcome and the effect of interventions aimed at optimizing StO₂.
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J Clin Monit Comput · Oct 2013
Review Meta AnalysisHeart rate variability indices for very short-term (30 beat) analysis. Part 1: survey and toolbox.
Heart rate variability (HRV) analysis over very short (<60 s) periods may be useful for monitoring dynamic changes in autonomic nervous system activity where steady-state conditions are not maintained (e.g. during drug administration, or the start or end of exercise). From the 1980s there has been a wealth of HRV indices produced in the quest for better measures of the change in parasympathetic and sympathetic activity. Many of the indices have been sparingly used and have not been investigated for application to short-term use. ⋯ The survey identified a comprehensive list of 115 indices that were subsequently coded and screened. Of these, 70 were unique and produced a finite number with 60 s data, so are included in the Toolbox. These indices require validation against physiological data before they can be applied to short-term HRV analysis of cardiac autonomic nervous system activity.
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J Clin Monit Comput · Oct 2013
Clinical TrialDetermination of breath isoprene allows the identification of the expiratory fraction of the propofol breath signal during real-time propofol breath monitoring.
Real-time measurement of propofol in the breath may be used for routine clinical monitoring. However, this requires unequivocal identification of the expiratory phase of the respiratory propofol signal as only expiratory propofol reflects propofol blood concentrations. Determination of CO2 breath concentrations is the current gold standard for the identification of expiratory gas but usually requires additional equipment. ⋯ Overall bias between the two data extraction methods was -0.12 ppb. The lower and the upper limits of the 95 % CI were -0.69 and 0.45 ppb. Determination of isoprene breath concentrations allows the identification of the expiratory propofol signal during real-time breath monitoring.
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J Clin Monit Comput · Oct 2013
New concept using Passive Infrared (PIR) technology for a contactless detection of breathing movement: a pilot study involving a cohort of 169 adult patients.
A pilot study has been conducted to validate the Breath Motion Detecting System (BMDS), a new concept using Passive Infrared (PIR) technology for a contactless detection of respiratory movements. The primary objective of the study was to show if movements detected during sleep by the BMDS were indeed related to breathing. This medical device is not intended to measure the respiratory rate, but in a second step, it will be able to detect pathological central apnea in adults. ⋯ The data recorded by the BMDS demonstrate the ability of the PIR technology to detect respiratory movements in adults. The concept is practical, inexpensive and safe for the patient. Further studies with respiratory inductive plethysmography are needed to investigate the potential of BMDS to detect central apneas.
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J Clin Monit Comput · Oct 2013
Randomized Controlled TrialRespiratory parameters as a surrogate marker for duration of intubation: potential application of automated vital sign collection.
Prolonged time during endotracheal tube placement has been associated with poor outcomes, including cardiac arrest and death. For this reason, the accurate measurement of the duration of intubation time is an important metric in studies that evaluate interventions to improve airway outcomes. In the current study we correlated the gaps in routinely measured ventilatory parameters with duration of the intubation procedure to determine if these intervals could be used to accurately calculate the intubation time. ⋯ The gap in measured tidal volume of 39 ± 53 s most closely approximated the actual duration of intubation of 38 ± 28 s, (R(2) = 0.85, y = x - 0.87). During intubation, the disappearance gaps in tidal volume, and the airway pressure and flow waveforms highly correlate with the duration of the intubation procedure and may be useful in the evaluation of airway management interventions. However, just as there are limitations to a labor-intensive method of recording airway management timing, there are limitations to using an automated method.