Articles: monitoring.
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Journal of anesthesia · Dec 1997
Titration of propofol infusion using processed electroencephalogram during combined general and spinal anesthesia.
To determine the necessary mean infusion rate of propofol during combined nitrous oxide (N2O) and propofol spinal anesthesia by using the processed electroencephalogram (pEEG). ⋯ Titration of propofol infusion using SEF during combined general and spinal anesthesia provided a rapid recovery without any clinical signs of inadequate anesthesia.
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SUTIL is an intelligent monitoring system for intensive and exhaustive follow up of patients in coronary care units. This system processes electrocardiographic and hemodynamic signals in real time, with the main objective of detecting ischemic episodes. ⋯ In addition to basic tasks, those at higher levels will also be presented. Some of these latter tasks attempt to mimic, to some extent, the way in which the human expert operates.
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We have examined the spectral components of heart rate variability (HRV) during induction of anaesthesia with thiopentone, tracheal intubation and subsequent inhalation of isoflurane-nitrous oxide. Commonly used spectral analysis methods such as fast Fourier transformation or autoregressive modelling require stationary data and are not suitable for the rapidly changing HRV data in this period. An advanced spectral analysis method, time-frequency analysis, which can treat non-stationary data, was used in this study. ⋯ Mid-frequency power (MF, 0.08-0.15 Hz), high-frequency power (HF, 0.15-0.5 Hz) and MF/HF ratio at baseline, after induction (before intubation), immediately after intubation and during maintenance periods were calculated and compared. MF and HF powers decreased after induction and were reduced further in the maintenance period but MF/HF ratio remained unchanged after induction. Immediately after intubation MF and HF powers did not differ significantly from the immediate pre-intubation values, but MF/HF ratio did.
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This report summarizes our experience in evaluating a series of 168 patients who underwent a total of 175 carotid endarterectomy procedures under local anesthesia. Patients were monitored by stump pressure (SP) measurement and transcranial Doppler scanning (TCD). The need for shunting was compared between SP/TCD flow velocity reduction and the awake response (gold standard). ⋯ SP measurement using a 50 mm Hg cutoff appears to be a reliable predictor of clamping ischemia but requires the use of a shunt in 17% of the patients who would otherwise not require this procedure. In contrast, TCD has greater specificity but is associated with a lower sensitivity, with 17% false negative results. In our experience, both SP and TCD show limitations, as they overestimate or underestimate carotid endarterectomy procedures in need of a shunt. We believe that sensitivity is more important than specificity in carotid endarterectomy, and thus conclude that TCD flow velocity measurement is not an optimal method for detecting clamping ischemia.
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This is a prospective study of the methodology and clinical applications of motor evoked potentials (MEPs) during surgery for intramedullary spinal cord tumors. ⋯ MEP monitorability was a better predictor of functional outcome than the patient's preoperative motor status for the adult group. Significant predictors of MEP monitorability in the adult group were preoperative motor function (P < 0.01), history of no previous treatment (surgery or irradiation) (P < 0.01), and small tumor size (P < 0.05). Weak associations with monitorable MEPs existed for low-grade tumors (P = 0.09), the presence of baseline somatosensory evoked potentials (P = 0.10), and tumor pathological abnormalities (ependymoma) (P = 0.13). No associations were determined for sex (P > 0.4), associated syrinx (P > 0.3), or tumor location (P > 0.5). In the pediatric group, none of the examined factors were associated with MEP monitorability (P > 0.3). A decline of more than 50% in MEP amplitude during tumor removal should serve as a serious warning sign to the surgeon.