Journal of clinical monitoring and computing
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For determining the adequacy of ventilation, conventional pulse oximetry should be amended by PaCO2 (= arterial carbon dioxide partial pressure). This study investigates the precision of carbon dioxide measurements of the first digital ear-clip sensor providing continuous non-invasive monitoring of PaCO2, SpO2 (= functional arterial oxygen saturation as estimated with a pulse oximeter) and pulse rate and compares it to two conventional analog oximeters. ⋯ Combined digital SpO2/ PcCO2 ear sensors are very promising to allow for a fast and reliable monitoring of patient's oxygenation, hyper-/hypocapnia and ventilation with one single non-invasive probe. Optimal primary signal processing--amplification and digitalisation within the probe--allow for fast and reliable downstream signal processing algorithms. The resulting short SpO2 response times give the medical staff more time to take appropriate actions.
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J Clin Monit Comput · Apr 2004
Evaluation of impedance based indices of cardiac contractility in dogs.
Cardiac function can be monitored simply and safely by the impedance method. A number of parameters that reflect cardiac contractility can be derived from the impedance waveform. These include the systolic time ratio (STR), the index of contracticity (IC), the acceleration index (ACI) and the Heather index. This study evaluates their reliability. ⋯ ACI and the Heather index were the most reliable impedance derived indices of cardiac contractility.
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J Clin Monit Comput · Apr 2004
Clinical TrialIntramyocardial oxygen monitoring in coronary artery bypass surgery.
In coronary artery bypass surgery various parameters have been used to monitor patients clinical status. Direct monitoring of myocardial oxygenation can be performed by measuring intramyocardial partial oxygen tension pressure (p ti O2). This study was performed to determine the perioperative time course of this parameter in correlation to standard monitoring parameters. ⋯ Determination of intramyocardial partial oxygen pressure in patients undergoing bypass surgery shows characteristic changes. Changes in p ti O2 as a direct online parameter of myocardial oxygenation occur immediately after procedures that influence myocardial perfusion and therefore, may help to detect potential complications earlier than standard monitoring parameters in cardiac surgery.
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J Clin Monit Comput · Apr 2004
Comparative StudyA dual closed-loop control system for mechanical ventilation.
Closed-loop mechanical ventilation has the potential to provide more effective ventilatory support to patients with less complexity than conventional ventilation. The purpose of this study was to investigate the effectiveness of an automatic technique for mechanical ventilation. ⋯ The controller maintained the arterial blood gases within normal limits under steady-state conditions and the transient response of the system was robust under various disturbances. The results of the study have showed that the proposed dual closed-loop technique has effectively controlled mechanical ventilation under different test conditions.
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Audible pulse tones, based on a variable-pitch frequency scale, allow the anesthesiologist to determine the patient's oxygen saturation without constant visual examination of the monitor display. The ability to reliably detect oxygen saturation levels based on audible pulse tones may be compromised when multiple pulse oximeter systems are used. The goal of this observational study was to examine the pitch frequency scales from several different pulse oximeter manufacturers. ⋯ With such variation among systems, the ability to accurately determine oxygen saturation from a pulse tone may be hindered. In locations where different pulse oximeter systems are encountered, the potential for confusion exists. Anesthesiologists need to be aware of these differences, and should familiarize themselves with the audible frequency scale of a particular pulse oximeter model before its use.