Anesthesiology
-
Based on a train-of-four (TOF) ratio greater than 0.70 as the standard of acceptable clinical recovery, undetected postoperative residual paralysis occurs frequently in postanesthesia care units. In most published studies, detailed information regarding anesthetic management is not provided. The authors reexamined the incidence of postoperative weakness after the administration of long- and short-acting neuromuscular blockers because few, if any, such comparative studies are available. ⋯ These results suggest that if nondepolarizing neuromuscular blockers are administered using tactile evaluation of the TOF count as a guide, critical episodes of postoperative weakness in the postanesthesia care unit should occur infrequently even with long-acting relaxants. Nevertheless, if full recovery is defined as return to a TOF ratio of 0.90 or more, then short-acting agents would appear to offer a wider margin of safety.
-
Randomized Controlled Trial Clinical Trial
Interactions between midazolam and remifentanil during monitored anesthesia care.
Remifentanil, an ultra-short-acting opioid analgesic, may be useful as an intravenous adjuvant to local anesthesia for treating patient discomfort and pain during monitored anesthesia care (MAC). However, the remifentanil dose requirements, interactions with other commonly used sedative drugs (such as midazolam), and recovery characteristics after ambulatory procedures have not been determined. Therefore, this study was designed to evaluate the safety and efficacy of remifentanil alone and in combination with different doses of midazolam during MAC. ⋯ Use of remifentanil alone for MAC did not provide optimal sedation during local anesthesia. However, 0.05 to 0.1 microgram.kg-1.min-1 remifentanil in combination with 2 mg midazolam given intravenously, provided effective sedation and analgesia during MAC in healthy patients classified as American Society of Anesthesiologists status 1 to 2. Midazolam also produced dose-dependent potentiation of remifentanil's depressant effect on respiratory rate. In outpatients receiving a combination of midazolam and remifentanil during local anesthesia, the level of sedation appears to influence the incidence of both intraoperative pruritus and PONV.
-
Although evidence suggests that secretions lining the inner wall of the endotracheal tube (ETT) often reduce its cross-sectional area, no data are available on the work of breathing as affected by the ETT. A noninvasive method is proposed for estimating the additional work of breathing necessitated by the ETT in patients whose lungs are mechanically ventilated. This method (the acoustic-Blasius method) involves (1) determining the inner geometry of the ETT using the acoustic reflection method and (2) using these geometric data to solve the Blasius equation that characterizes the ETT pressure drop-flow relation. ⋯ The data show that the acoustic-Blasius method allows noninvasive quantification of the ETT-related work of breathing in situ.
-
Laparoscopic surgical procedures are being performed in pregnant women with increasing frequency. Maternal-fetal physiologic changes occurring during intraabdominal carbon dioxide insufflation are poorly understood, and maternal-fetal safety is of concern during carbon dioxide pneumoperitoneum. A previous pilot study using end-tidal carbon dioxide-guided ventilation resulted in maternal and fetal acidosis and tachycardia during carbon dioxide pneumoperitoneum. Using serial arterial PCO2 to guide ventilation, this study was designed to evaluate maternal-fetal cardiopulmonary status, uterine blood flow, and the intraamniotic pressure effects of intraabdominal carbon dioxide insufflation in singleton pregnant ewes between 120 and 135 days of gestation. ⋯ During the 1-h insufflation, a marked increase in PaCO2-to-end-tidal carbon dioxide gradient was observed, suggesting that capnography may be an inadequate guide to ventilation during carbon dioxide pneumoperitoneum in the pregnant patient. No other significant circulatory changes were observed.
-
Letter Case Reports
Spinal meningitis masquerading as postdural puncture headache.