Journal of clinical monitoring and computing
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The authors evaluated an analyser for the determination of propofol concentrations in whole blood. The Pelorus 1000 (Sphere Medical) measures propofol concentrations in around 5 min without the requirement for sample preparation. The performance of the analyser was characterised with respect to linearity, precision in control solutions and whole blood and method comparison to an HPLC based reference method. ⋯ The only cross interference of note is to a highly elevated level of conjugated bilirubin, while low haematocrit levels lead to a 0.13 μg/ml under reading with respect to the HPLC reference. The system fulfils the requirements for measurement of propofol concentrations in whole blood samples with precision and accuracy suitable for elucidating propofol pharmacokinetics at clinically relevant concentrations. With no requirement for sample preparation and a fast time to results, the analyser opens up the possibility of studies to measure and respond to blood propofol concentrations in patients in close to real time.
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J Clin Monit Comput · Feb 2012
Developing an algorithm for pulse oximetry derived respiratory rate (RR(oxi)): a healthy volunteer study.
The presence of respiratory information within the pulse oximeter signal (PPG) is a well-documented phenomenon. However, extracting this information for the purpose of continuously monitoring respiratory rate requires: (1) the recognition of the multi-faceted manifestations of respiratory modulation components within the PPG and the complex interactions among them; (2) the implementation of appropriate advanced signal processing techniques to take full advantage of this information; and (3) the post-processing infrastructure to deliver a clinically useful reported respiratory rate to the end user. A holistic algorithmic approach to the problem is therefore required. We have developed the RR(OXI) algorithm based on this principle and its performance on healthy subject trial data is described herein. ⋯ These data indicate that RR(oxi) represents a viable technology for the measurement of respiratory rate of healthy individuals.
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J Clin Monit Comput · Feb 2012
Case ReportsProtection of the remaining spinal cord function with intraoperative neurophysiological monitoring during paraparetic scoliosis surgery: a case report.
To demonstrate the usefulness of rectus femoris muscle MEPs monitoring in a paraparetic neuromuscular scoliosis case. ⋯ Intraoperative neurophysiological monitoring should be used for neuromuscular scoliosis cases with paraparesis if proximal function, such as the rectus femoris muscle, exists.
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J Clin Monit Comput · Feb 2012
New airway device for ventilation and monitoring in pediatric patients undergoing MRI study.
A method of administering continuous positive airway pressure via a new airway device to prevent upper airway obstruction and preserve spontaneous respiration under total intravenous anesthesia has been adapted for children undergoing deep sedation for MRI studies. Presented herein is a retrospective study of 45 pediatric patients, ages 5 months to 7 years, who underwent an MRI study under general anesthesia using a modified nasal vestibule airway (NVA®), a pressure-sealing nasal cannula that can be used in conjunction with an anesthesia circuit to deliver nasal-CPAP during anesthesia. After inhalation induction of anesthesia with sevoflurane, an intravenous infusion of propofol was used to maintain anesthesia. ⋯ A new approach is offered to maintain airway patency, monitoring and spontaneous respirations in pediatric patients undergoing MRI study. This pressure-sealing nasal cannula can deliver CPAP under anesthesia while avoiding the requirement of an invasive airway and facilitating additional monitoring and control not possible with an ordinary nasal cannula. This NVA may be used in other locations in pediatric patients where endotracheal intubation is not necessary or impossible.
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J Clin Monit Comput · Feb 2012
Validation of indirect calorimetry for measurement of energy expenditure in healthy volunteers undergoing pressure controlled non-invasive ventilation support.
The aim of this validation study was to assess the reliability of gas exchange measurement with indirect calorimetry among subjects who undergo non-invasive ventilation (NIV). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured in twelve healthy volunteers. Respiratory quotient (RQ) and resting energy expenditure (REE) were then calculated from the measured VO2 and VCO2 values. ⋯ The change of sampling air flow had no statistically significant effect on any of the above parameters. We found that REE can be accurately measured with an indirect calorimeter also during NIV-supported breathing and the change of sampling air flow does not distort the gas exchange measurement. A higher sampling air flow in indirect calorimetry decreases the possibility for air leakages in the measurement system and increases the reliability of REE measurement.