Journal of clinical monitoring and computing
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J Clin Monit Comput · Aug 1998
Influence of the reference gas of paramagnetic oxygen analyzers on nitrogen concentrations during closed-circuit anesthesia.
Nitrogen (N2) may accumulate to unacceptable levels during closed-circuit anesthesia (CCA) when the sampled gases are redirected to the anesthesia circuit, because many gas analyzers entrain air as a reference gas to calibrate for oxygen analysis. Using oxygen instead of air as the reference gas for paramagnetic oxygen analysis could attenuate N2 accumulation. Forty-three adult ASA physical status I-III patients undergoing a variety of peripheral and abdominal procedures were assigned to one of two groups, depending on the reference gas used by a paramagnetic oxygen analyzer, either air (group I, n = 23) or oxygen (group II, n = 20). ⋯ N2Et0min, N2Et5min, and N2Et55min were 0.87+/-0.93, 2.6+/-1.5, and 10.1+/-2.9%, respectively. The correlation (r2) between N2Et55min and N2Et0min was 0.04, and between N2Et55min and N2Et5min it was 0.40. We conclude that paramagnetic oxygen analyzers that use oxygen as the reference gas significantly attenuate N2 accumulation during CCA, which may reduce the need for frequent flushing of the anesthesia system, may provide more constant oxygen and nitrous oxide concentrations, and may simplify pharmacokinetic studies of potent inhaled anesthetics.
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J Clin Monit Comput · Aug 1998
Availability of records in an outpatient preanesthetic evaluation clinic.
Despite efforts to develop electronic access to medical records, there are few data on availability of past evaluations. Typical analyses assess only availability of paper charts. We studied the availability of prior internal and external medical documentation in the preanesthetic clinic of our tertiary teaching institution, which has had access to hospital-wide electronic records for five years. ⋯ Anesthesiologists retrieved, and added to the perioperative evaluation, information from previous encounters for 16% of patients. Despite our hospital-wide electronic records, internal information was missing for 22% of patients. Uneven deployment, and reliance on transcription may contribute to failures. A national electronic medical records system would benefit the 8% (one out of twelve) of outpatients missing external records identified in this study. For many patients, optimal medical understanding was not achieved during the planned preanesthetic evaluation.
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J Clin Monit Comput · Aug 1998
Reflectance pulse oximetry--principles and obstetric application in the Zurich system.
Transmission and reflectance are the two main modes of pulse oximetry. In obstetrics, due to the absence of a transilluminable fetal part for transmission oximetry, the only feasible option is the reflectance mode, in which sensor and detector are located on the same surface of the body part. ⋯ We have designed, developed, constructed and tested a reflectance pulse oximeter with the possibility to adjust the electronic circuits and signal processing in order to determine the effects of various parameters on signal amplitude and wave-form and to optimize the sensitivity and spatial arrangement of the optical elements. Following an explanation of the principles of reflectance pulse oximetry, we report our experience with the design, development, construction and field-testing of an in-house reflectance pulse oximetry system for obstetric application.
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Mixtures of helium and oxygen are regaining a place in the treatment of obstruction of the upper and lower respiratory tract. The parenchymal changes during the course of IRDS or ARDS may also benefit from the reintroduction of helium/oxygen. In order to monitor and document the effect of low-density gas mixtures, we evaluated the Datex AS/3 Side Stream Spirometry module with D-lite (Datex-Engstrom Instrumentarium Corporation, Finland) against two golden standards. ⋯ Measurements with the D-lite using low-density gases are satisfactorily contained in best-fit equations with a standard deviation of less than 5% during all ventilatory modes and mixtures.
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J Clin Monit Comput · Aug 1998
A real-time algorithm to improve the response time of a clinical multigas analyser.
An algorithm to improve the response time of a clinical respiratory multigas analyser is presented. ⋯ The algorithm provides an improvement on the relatively slow response times of the clinical gas analyser for breath-by-breath time-dependent applications. The same algorithm can also be applied to other instruments which have slow response times.