Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1991
Randomized Controlled Trial Comparative Study Clinical TrialEfficacy of esmolol versus alfentanil as a supplement to propofol-nitrous oxide anesthesia.
In 97 outpatients undergoing ambulatory arthroscopic procedures, we compared esmolol with alfentanil when used to supplement propofol-N2O-atracurium anesthesia according to a randomized, double-blind protocol. After an initial intravenous dose of 16 micrograms/kg alfentanil, or 2 mg/kg of esmolol, a variable-rate infusion of alfentanil or esmolol was administered to maintain a stable heart rate. After induction of anesthesia with 2.5 mg/kg of propofol, mean arterial pressure decreased to a larger extent in the alfentanil-treated patients. ⋯ There were no significant differences in the incidences of nausea and vomiting between the two groups. The authors conclude that esmolol may be used in place of alfentanil to supplement propofol-N2O-atracurium anesthesia in outpatients undergoing arthroscopic procedures. However, hemodynamic responses to tracheal intubation were larger with esmolol, and avoidance of alfentanil did not decrease the incidence of postoperative nausea and vomiting in this outpatient population.
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Data on the normal depth of insertion of double-lumen tubes have not been published. We studied 101 adult patients undergoing thoracic operations whose tracheas were intubated with a left double-lumen tube. ⋯ The correlation between depth of insertion and height was highly significant (P less than 0.0001) for both male and female patients. As depth of DLT insertion at any given height was normally distributed, a technique to confirm correct double-lumen tube position always should be used after initial placement.
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Anesthesia and analgesia · Nov 1991
Clinical Trial Controlled Clinical TrialVisual assessment of train-of-four and double burst-induced fade at submaximal stimulating currents.
The influence of current intensity on visual assessment of fade in response to train-of-four (TOF) and two modes of double-burst stimulation (DBS) was determined to assess the utility of low-current neurostimulation. Each of 150 sets of assessments (in 51 patients) included a mechanographic TOF at 60 mA followed by visual assessments of TOF, DBS3,3 (two minitetanic bursts of three stimuli each), and DBS3,2 (a burst of three followed by a burst of two impulses) at 20, 30, 50, and 60 mA in random order. For the range of mechanographic TOF ratios between 0.41 and 0.70, visual assessment of TOF fade failed to identify fade in 33%, 36%, 44%, and 58% of cases at 20, 30, 50, and 60 mA, respectively. ⋯ At each current tested, DBS was more sensitive in detecting fade visually than TOF. The accuracy of visual fade detection was not influenced significantly by level of observer training. In conclusion, visual assessment of fade by novice and expert observers is improved by testing at low currents.
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Anesthesia and analgesia · Nov 1991
Oxygen uptake and mixed venous oxygen saturation during aortic surgery and the first three postoperative hours.
This study was designed to determine the significance of changes in mixed venous oxygen saturation (SVO2) associated with aortic surgery. In 12 patients undergoing aortic aneurysm repair, SVO2 was monitored using a fiberoptic pulmonary arterial catheter, and oxygen uptake (VO2) was measured at 2-min intervals by a mass-spectrometer system. Excluding the phase of aortic clamping, VO2, hemoglobin, and arterial oxygen saturation were moderately stable during anesthesia, and changes in SVO2 were correlated with changes in cardiac output (CO). ⋯ They were especially marked in the patients whose preoperative left ventricular ejection fraction was less than 50%. We conclude that SVO2 changes are an indicator of same-direction changes in CO during general anesthesia except during periods of aortic clamping. The interpretation of SVO2 changes is more complex during aortic clamping and during the immediate postoperative period, two critical periods during which simultaneous changes in VO2 and CO occur.