Journal of clinical monitoring
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During general anesthesia, different modes of nerve stimulation are used for estimation of the degree of neuromuscular blockade. When switching between the different modes, it is important to know whether the preceding mode influences the responses to the succeeding mode, and if so, for how long. The object of our study was to determine the number of stimulations required for stabilization of the muscular response when switching between double-burst stimulation (DBS) applied every 20 sec, train-of-four (TOF) applied every 12 sec, and posttetanic count (PTC) at surgical degrees of neuromuscular blockade. ⋯ When switching from DBS to TOF, 4 to 7 stimulations (56 to 92 sec) were required for stabilization of the T1 response. When switching from TOF to DBS, 3 stimulations (36 to 52 sec) were required for stabilization of the D1 response, and, finally, when switching from PTC to DBS, 5 to 11 stimulations (81 to 201 sec) were required for stabilization of the D1 response. Stabilization of D1 was faster following TOF than following PTC (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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The esophageal-tracheal Combitube (Sheridan, Inc., Argyle, NY) is a unique double lumen tube that has been introduced as an emergency intubation device. Since it is placed blindly, proper use requires determination of which lumen can be successfully used for ventilation. The Easycap (Nellcor, Inc., Pleasanton, CA) is a colorimetric carbon dioxide detector that reacts with exhaled gas to indicate proper tracheal tube location. The purpose of this study was to determine if the Easycap can be used to identify which Combitube lumen is patent to the trachea after blind placement in dogs. ⋯ Our results suggest that the Easycap device may be useful with the Combitube, although human data are required.
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Comparative Study
Clinical evaluation of continuous noninvasive blood pressure monitoring: accuracy and tracking capabilities.
A continuous, noninvasive device for blood pressure measurement using pulse transit time has been recently introduced. We compared blood pressure measurement determined using this device with simultaneous invasive blood pressure measurements in 35 patients undergoing general endotracheal anesthesia. Data were analyzed for accuracy and tracking ability of the noninvasive technique, and for frequency of unavailable pressure measurements by each method. ⋯ When blood pressure measured invasively changed over time by more than 10 mm Hg, the noninvasive technique accurately tracked the direction of change 67% of the time. During the entire study, 3.2% of the invasive measurements were unavailable and 12.9% of the noninvasive measurements were unavailable. The continuous noninvasive monitoring technique is not of sufficient accuracy to replace direct invasive measurement of arterial blood pressure, owing to relatively wide limits of agreement between the two methods.(ABSTRACT TRUNCATED AT 250 WORDS)
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During initial clinical tests to calibrate our reflectance pulse oximetry system, we observed serious physiologic limitations to the use of pulse oximetry in the forehead region. We present a case of simultaneous reflectance and transmission mode pulse oximetry monitoring in a child undergoing cardiac surgery for congenital cyanotic heart disease with a large intracardiac shunt. ⋯ We suggest that the difference was caused by vasodilatation and pooling of venous blood due to compromised venous return to the heart, and a combination of arterial and venous pulsations in the forehead region. This means that the reflectance pulse oximeter measured a mixed arterial-venous oxygen saturation.
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Comparative Study
Measurement of respiratory rate and timing using a nasal thermocouple.
The aims of this study were to assess aspects of the response of a small thermocouple to temperature change, and to evaluate whether such a thermocouple could be used intermittently to measure respiratory rate and timing by detecting the changes in nasal temperature occurring with breathing. ⋯ Intermittent measurements of respiratory rate and timing using a nasal thermocouple accurately reflected measurements obtained from nasal airflow using a pneumotachograph.