Journal of clinical monitoring
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Because the AVOXimeter uses disposable cuvettes and makes its measurements directly in whole blood without first hemolyzing the sample, it does not need the care and maintenance that conventional co-oximeters require, it operates faster than conventional co-oximeters, and it is less expensive. Therefore, the objectives of the study were (1) to evaluate the precision and linearity of the AVOXimeter's measurements of total hemoglobin concentration and oxyhemoglobin saturation; (2) to assess its long-term stability and thus the required interval for recalibration; (3) to determine whether measurements can be made without anticoagulants; and (4) to assess the feasibility of storing blood samples in the disposable cuvettes. ⋯ In our experience the test instrument was simple and easy to operate. It met the specification for precision and accuracy, its measurements were highly linear, and it maintained a stable calibration for one year. If the cuvettes are filled as soon as blood is drawn, anticoagulation is unnecessary. However, the cuvettes should be read with 1 min of filling the cuvette.
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We describe a computer algorithm that allows continuous, real-time evaluation of ventricular elastance (Ees), arterial elastance (Ea), and their coupling ratio in a clinical setting. In the conventional pressure-volume analysis of left ventricular (LV) contractility, invasive methods of volume determination and a significant, rapid preload reduction are required to generate Ees. With the help of automated border detection by transesophageal echocardiography, and a technique of estimating peak LV isovolumic pressure, Ea and Ees were determined from a single cardiac beat without the need for preload reduction. ⋯ Bias analysis showed a bias of -1.42 mmHg/cm2 for Ees with a SD of 4.88 mmHg/cm2, and limits of agreement of 8.15 mmHg/cm2 and -10.98 mmHg/cm2. The algorithm's stability to artifacts was also analyzed by comparing magnitudes of residuals of Ea and Ees from source signals with and without noise. With Ea differing by an average of 1.036 mmHg/cm2 and Ees differing by an average of 0.836 mmHg/cm2, the algorithm was found to be stable to artifacts in the source signals.
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To evaluate the accuracy of a new pulse oximeter in estimating the oxyhemoglobin (O2Hb) concentration in fetal arterial blood (SaO2) with either a high concentration of hemoglobin F (HbF) or a low concentration of O2Hb during labor. ⋯ SpO2 determined by a new reflectance pulse oximeter at the end of labor correlated with an immediate post-natal cord arterial blood sample before the first breath, with a mean and SD of bias of 8.5 +/- 6.2%. Reflectance pulse oximetry is a useful tool for continuous noninvasive monitoring of the fetal oxygen status during labor.
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To develop an instrument to help prevent pulmonary O2 toxicity, a syndrome that manifests itself in adult intensive care patients. ⋯ Testing the effectiveness of this instrument will require comparison with manual control of FIO2 in an appropriately designed trial.
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Patient awareness under minimal anesthesia may include the painful impulses of a nerve stimulator used for the monitoring of muscle relaxation. We present a case where discomfort from nerve stimulation was greater than that caused by the surgical incision or the endotracheal tube.