Journal of clinical monitoring
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Facial and hand muscles are used frequently for monitoring neuromuscular blockade. Therefore, we compared changes in electrically evoked muscle potential magnitude in upper facial and hypothenar muscles after fixed doses of neuromuscular blockers (succinylcholine, 750 micrograms/kg; pancuronium, 70 micrograms/kg; vecuronium, 50 micrograms/kg; and atracurium, 300 micrograms/kg). Face-hand comparisons were made in both anesthetized (nitrous oxide/narcotic, n = 51) and comatose (closed-head injuries, n = 5) patients. ⋯ The neuromuscular blockade in both the hand (49 +/- 54%) and the upper facial area (68 +/- 28%, P greater than 0.05) of comatose patients was smaller and more variable than that seen during anesthesia. These results illustrate the value of quantitative monitoring of neuromuscular function, especially during highly variable and unpredictable drug-induced blockade in the comatose state. We conclude that during narcotic-based anesthesia the upper facial and hand muscles are differentially sensitive to commonly used neuromuscular blockers.
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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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To compare values measured by a continuous intra-arterial blood gas monitoring system with those measured by conventional blood gas analyzer for the assessment of the clinical performance of a new device for measurement of PaO2, PaCO2, and arterial pH. ⋯ The PO2 and pH values derived from an intra-arterial blood gas monitoring system agreed well with the values measured by a conventional blood gas analyzer. However, the PCO2 value must be corrected due to an increase of drift, especially with extended use for more than 72 hours.
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Comparative Study
Reproducibility of thermodilution cardiac output determination in critically ill patients: comparison between bolus and continuous method.
A semi-continuous thermodilution method (CCO) was recently developed to measure cardiac output with less risk of bacterial contamination, fluid overload, and user-induced errors than the classical bolus technique (BCO). Previous comparison between these two methods showed negligible bias. However, large limits of agreement suggest that the two methods are not interchangeable. We hypothesized that this poor agreement may be due to differences in reproducibility. ⋯ Differences in reproducibility may explain the poor agreement between the CCO and BCO methods. The better reproducibility of the CCO method allows the detection of smaller variations in cardiac output and suggests the superiority of this new method.
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The purposes of this study were to evaluate the clinical utility of a colorimetric end-tidal CO2 (ETCO2) detector in confirming proper endotracheal intubation in patients requiring emergency intubation, to determine if this new device can be used as an adjunct to judge the effectiveness of cardiopulmonary resuscitation (CPR), and to determine whether the device can predict successful resuscitation from cardiopulmonary arrest. We studied prospectively 110 patients requiring emergency intubation for either respiratory distress (53 patients) or cardiopulmonary arrest (57 patients) by recording the color range of the indicator after the initial intubation. In patients who suffered a cardiopulmonary arrest, the color range was also recorded during CPR after the endotracheal tube was confirmed to be in the tracheal position and perfusion optimized, and at the moment CPR was stopped. ⋯ A low ETCO2 color range in 19 patients undergoing CPR was interpreted as low cardiac output and prompted the physicians to attempt to increase perfusion. Of the patients who underwent CPR, no patient whose ETCO2 level remained less than 2% was successfully resuscitated. Those patients who had an ETCO2 level greater than or equal to 2% had a significantly higher incidence of successful resuscitation.(ABSTRACT TRUNCATED AT 250 WORDS)