Journal of clinical monitoring
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Randomized Controlled Trial Comparative Study Clinical Trial
Radial artery cannulation: a comparison of 15.2- and 4.45-cm catheters.
Eighty-nine patients were studied prospectively to compare the incidence of postdecannulation arterial thrombosis and ischemic complications associated with percutaneous insertion of two different radial artery catheters. Patients scheduled for peripheral vascular surgery were randomized to receive a 15.2-cm (6 in, Argon Medical Corp.) or 4.45-cm (1.75 in, Arrow International, Inc.) 20-gauge, Teflon catheter. Extremity blood flow was evaluated prior to cannulation and again after decannulation with the modified Allen's test, pulse-volume plethysmography, and Doppler ultrasound. ⋯ Of the 8 patients with positive modified Allen's test who underwent radial artery cannulation, one suffered arterial occlusion. Radial artery cannulation with a 15.2-cm catheter was associated with a lower incidence of postdecannulation radial artery thrombosis than cannulation with the 4.45-cm catheter. Radial artery cannulation with longer catheters (greater than 5.0 cm) appears to be a safe practice.
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Current forms of brain monitoring, such as electroencephalography (EEG), have had limited clinical utility. The EEG records spontaneous cerebrocortical activity and thus is an indirect indicator of metabolic demand and, to a lesser extent, an indicator of mismatch of supply versus demand. Ischemia modulates EEG activity in ways that can usually be detected, but EEG patterns can be similarly modulated by many other factors, including temperature and pharmacologic manipulation. ⋯ We compared estimators of changes in microcirculatory blood volume using reflection at two wavelengths: 366 nm and 585 nm, the wavelengths for maximum and isobestic absorption. The results of the studies were as follows: (1) during transient hypoxia, NADH and local hemoglobin saturation signals changed in concert with arterial pulse oximetry, with changes in NADH lagging behind changes in saturation by an average of 5.3 seconds; (2) after hypocapnic ventilation to a mean PaCO2 of 20.2 +/- 0.8 mm Hg, NADH increased by 11.5 +/- 8.7% (as compared with maximal change during anoxia), local hemoglobin saturation decreased by 7.7 +/- 6.4%, and local blood volume decreased by 12.5 +/- 13%, while arterial SpO2 was unchanged; (3) our two measures of local blood volume were closely correlated during carbon dioxide perturbations, but poorly correlated during hypoxic perturbation; and (4) NADH fluorescence provided a more rapid, sensitive indicator of oxygen deprivation than did the EEG. During transient hypoxia, EEG changes occurred 57.4 +/- 10.4 seconds after the onset of decline in local hemoglobin saturation, after NADH had completed 50% of its maximal increase.
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This study was designed to assess the accuracy of end-tidal PCO2 and transcutaneous PCO2 as measurements of arterial PCO2 in extubated, spontaneously breathing patients recovering from general anesthesia. In 30 patients, measurement of arterial transcutaneous, and end-tidal PCO2 were taken simultaneously with body temperature approximately every 15 minutes over a 2-hour period. Arterial PCO2 values were corrected for body temperature. ⋯ Thirty-six percent of the capnogram tracings obtained did not develop a plateau phase. We found poor correlation between end-tidal and arterial PCO2 regardless of the shape of the capnogram tracing, as well as poor correlation between transcutaneous and arterial PCO2. Although the measurements of bias and precision of noninvasive PCO2 monitors in this population are comparable to studies in other populations, we advise caution in relying on the routine use of PETCO2 or PsCO2 for the noninvasive assessment of respiratory depression in extubated, spontaneously breathing patients recovering from general anesthesia.
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We have developed a computerized neuromuscular monitoring system (NMMS) using commercially available subsystems, i.e., computer equipment, clinical nerve stimulator, force transducer, and strip-chart recorder. This NMMS was developed for acquisition and analysis of data for research and teaching purposes. Computer analysis of the muscle response to stimulation allows graphic and numeric presentation of the twitch response and calculated ratios. ⋯ The NMMS has functioned well in the operating room environment. We have had no episodes of electrocautery interference with the computer functions. The automated features have enhanced the utility of the NMMS.(ABSTRACT TRUNCATED AT 250 WORDS)
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Two patients are described in whom double-lumen endotracheal tube malplacement and its ventilatory consequences were not detected by infrared capnography. Problems were suspected on auscultation, and the malplacement was diagnosed by means of bronchospirometry. We conclude that bronchospirometry helps detect problems with endotracheal intubation.