Anesthesia and analgesia
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Anesthesia and analgesia · Mar 2002
Comparative StudyThe neuromuscular transmission module versus the relaxometer mechanomyograph for neuromuscular block monitoring.
The neuromuscular transmission module (M-NMT) is an integrated piezoelectric motion sensor module incorporated in the AS/3(TM) anesthesia monitor. We compared the neuromuscular block of 0.6 mg/kg rocuronium (twice the 95% effective dose) monitored by the M-NMT with that monitored by the Relaxometer mechanomyograph (MMG). The two monitors were alternately allocated to the left or right hands of 20 patients. T(1)%, the first twitch of the train-of-four (TOF), and the TOF ratio (T(4)/T(1)) were used for evaluating the neuromuscular block. There was no significant difference in the mean (min) plus minus SD onset time or time to 0.8 TOF ratio recovery measured by the M-NMT (1.5 plus/minus 0.3, 49.4 plus/minus 8.1) compared with MMG (1.8 plus/minus 0.6, 50.9 plus/minus 9.9), respectively. However, the time (min) to 25% T(1) recovery was significantly longer when monitored by the M-NMT (25.6 plus/minus 8) than by the MMG (20.2 plus/minus 6.3). During recovery from neuromuscular block, the difference between the TOF ratios measured by the two monitors showed a bias of -0.031, and the limits of agreement (bias plus/minus 1.96 SD) were -0.281 and +0.22. The M-NMT monitor could determine the time to tracheal intubation as well as full recovery from neuromuscular block, but it lagged behind the MMG in determining the time to rocuronium repeat dose administration. ⋯ Compared with the Relaxometer mechanomyograph, the neuromuscular transmission module could equally indicate time to tracheal intubation and full recovery from 0.6 mg/kg rocuronium neuromuscular block. Its small quick-fit sensor has the advantage, in an often crowded and busy operating room, of being incorporated in the AS/3(TM) anesthesia workstation.
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The tracheas of obese patients may be more difficult to intubate than those of normal-weight patients. We studied 100 morbidly obese patients (body mass index >40 kg/m(2)) to identify which factors complicate direct laryngoscopy and tracheal intubation. Preoperative measurements (height, weight, neck circumference, width of mouth opening, sternomental distance, and thyromental distance) and Mallampati score were recorded. The view during direct laryngoscopy was graded, and the number of attempts at tracheal intubation was recorded. Neither absolute obesity nor body mass index was associated with intubation difficulties. Large neck circumference and high Mallampati score were the only predictors of potential intubation problems. Because in all but one patient the trachea was intubated successfully by direct laryngoscopy, the neck circumference that requires an intervention such as fiberoptic bronchoscopy to establish an airway remains unknown. We conclude that obesity alone is not predictive of tracheal intubation difficulties. ⋯ In 100 morbidly obese patients, neither obesity nor body mass index predicted problems with tracheal intubation. However, a high Mallampati score (greater-than-or-equal to 3) and large neck circumference may increase the potential for difficult laryngoscopy and intubation.
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Anesthesia and analgesia · Mar 2002
Comparative StudyThe effects of abdominal opening on respiratory mechanics during general anesthesia in normal and morbidly obese patients: a comparative study.
Morbid obesity has a profound effect on respiratory mechanics and gas exchange. However, most studies were performed in morbidly obese patients before or after anesthesia. We tested the hypothesis that anesthesia and abdominal opening could modify the elastic and resistive properties of the respiratory system. ⋯ Obese patients also presented higher resistances of the total respiratory system, lung and chest wall, as well as "additional" lung resistance. Mainly in obese patients, laparotomy provoked a significant increase in lung compliance and decrease in "additional" lung resistance 1 h after the peritoneum was opened, which returned to original values after the peritoneum had been closed (P < 0.005). In obese patients, low respiratory compliance and higher airway resistance were mainly determined by the lung component.
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Anesthesia and analgesia · Mar 2002
Assessing sedation with regional anesthesia: inter-rater agreement on a modified Wilson sedation scale.
A valid and reliable means for measuring sedation during regional anesthesia would be valuable for both research and practice. Current methods of monitoring sedation include machine-, patient-, and observer-based assessment. The reliability of machine-based methods is limited at lower levels of sedation, whereas patient-based methods are impractical at higher levels. Observer-based methods offer the best alternative for assessing sedation during regional anesthesia; however, their reliability has not been adequately documented. We examined the interrater reliability of the Wilson sedation scale. Sedation was assessed by pairs of anesthesia care providers in 100 patients undergoing surgical procedures with regional anesthesia. On the basis of the findings, the scale was modified, and 50 additional patients were assessed. The study protocol called for a series of standardized stimuli administered by a research assistant. Raters were blinded to each other's ratings. Interrater reliability was assessed by using the kappa statistic, a measure of actual agreement beyond agreement by chance. When continuing checks on its operationalization and reliability are included, the modified Wilson scale provides a simple and reliable means by which to assess and monitor intraoperative sedation. ⋯ We evaluated the interrater reliability of the Wilson scale for measuring sedation during regional anesthesia. Paired anesthesia care providers' ratings of patient sedation indicated very good interrater reliability in both the original scale and a modified version. The modified Wilson scale provides a quick noninvasive means of monitoring sedation during regional anesthesia.
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Anesthesia and analgesia · Mar 2002
Case ReportsTension pneumothorax during flexible fiberoptic bronchoscopy in a newborn.
A newborn undergoing flexible fiberoptic bronchoscopy before repair of a tracheoesophageal fistula developed a life-threatening tension pneumothorax. The mechanisms of this complication are discussed and recommendations are made for preventing this complication.