Anesthesia and analgesia
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The esophageal-tracheal Combitube((R)) (ETC; Kendall-Sheridan Catheter Corp., Argyle, NY) is a new device designed for difficult airways and emergency intubation. The manufacturer recommends that the ETC model 37F SA be used in patients with a height of between 122 and 152 cm. The aim of this study was to evaluate whether ventilation is effective and reliable in patients taller than 152 cm by using the ETC 37F SA in the esophageal position. Also, we evaluated whether the airway protection is adequate and whether direct intubation of the trachea with the ETC inserted in the esophagus is possible. We studied 25 anesthetized, paralyzed adult patients, 150 to 180 cm in height. Methylene blue was given orally to all patients before anesthesia induction. Under direct vision, a ETC 37F SA was inserted in the esophagus of all patients. The pharyngeal balloon inflation volume was titrated to air leak and cuff pressures were measured. During surgery, a laryngoscope was inserted into the pharynx with the pharyngeal balloon deflated and the laryngoscopic view was evaluated by using the Cormack-Lehane scale. The presence of methylene blue in the hypopharynx was investigated by direct laryngoscopic vision. Ventilation was effective and reliable in all 25 patients who were 150 to 180 cm in height (average 169 +/- 7 cm). In addition, a direct relationship between the pharyngeal balloon volume and patient height was established (P < 0.05), by using linear regression models. The laryngoscopic view of the glottis was adequate to allow direct tracheal intubation. No trace of methylene blue was detected in the hypopharynx. The ETC Model 37F SA may be used in patients from 122 to 185 cm in height. The trachea could be directly intubated with the ETC in the esophageal position in patients with normal airways. The airway protection appears to be adequate. ⋯ The esophageal-tracheal Combitube((R)) Model 37F SA (Kendall-Sheridan Catheter Corp., Argyle, NY) may be used in patients from 122 to 185 cm in height. The trachea could be directly intubated with the Combitube((R)) in esophageal position in patients with normal airways. The airway protection appears to be adequate.
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The relationship between epidural analgesia and cesarean delivery remains controversial. Several studies have documented an association, although others have not. This inconsistency may result from an association between severe labor pain and dystocia. We hypothesized that dystocia causes severe labor pain, such that more epidural medication is required to maintain comfort. We examined the relationship between labor outcome and severe pain, defined by the number of supplemental epidural boluses. We retrospectively reviewed the anesthesia records of 4493 parturients who received small-dose labor epidural analgesia. An independent association was found between operative delivery and maternal age, body mass index, nulliparity, fetal weight, induction of labor, and the number of boluses required during labor. By using multivariate analysis, the odds ratio of cesarean delivery among women who required at least three boluses was 2.3 compared with those who required two boluses or less. No association was found between the concentration of bupivacaine in the epidural infusion and operative delivery. Because women with cesarean deliveries appeared to have more pain, degree of labor pain may be a confounding factor in studies examining epidural analgesia and outcome. ⋯ This is a retrospective observational study demonstrating an association between labor pain and cesarean delivery. Our results provide an alternative explanation of why epidural analgesia is associated with cesarean delivery.
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Anesthesia and analgesia · Apr 2000
Anticoagulation for cardiac surgery in patients receiving preoperative heparin: use of the high-dose thrombin time.
Patients receiving heparin infusions have an attenuated activated clotting time (ACT) response to heparin given for cardiopulmonary bypass (CPB). We compared patients receiving preoperative heparin (Group H) to those not receiving heparin (REF group) with respect to ACT, high-dose thrombin time (HiTT), and markers of thrombin generation during CPB. Sixty-five consecutive patients (33 Group H, 32 REF group) undergoing elective CPB were evaluated. ACT and HiTT were measured at multiple time points. Plasma levels of thrombin-antithrombin III complex and fibrin monomer were determined at baseline, during CPB, and after protamine administration. Transfusion requirements and postoperative blood loss were measured and compared. ACT values after heparinization increased less in Group H and were significantly lower than those in the REF group (P < 0.01). HiTT values did not differ significantly between the two groups. Blood loss and transfusion requirements were not significantly different between the two groups. Plasma levels of thrombin-antithrombin III complexes and fibrin monomer also did not differ between groups at any time, despite a lower ACT in Group H after heparinization and during CPB. Our data suggest that thrombin formation and activity are not enhanced in patients receiving heparin therapy, despite a diminished ACT response to heparin. The utility of ACT and the threshold values indicative of adequate anticoagulation for CPB are relatively undefined in patients receiving preoperative heparin. HiTT should be investigated as a safe and accurate monitor of anticoagulation for CPB in patients receiving preoperative heparin therapy. ⋯ The diminished activated clotting time response to heparin, in patients receiving preoperative heparin therapy, poses difficulties when attempting to provide adequate anticoagulation for cardiopulmonary bypass. Current data suggest that heparin resistance is not observed when high-dose thrombin time is used to monitor anticoagulation and that a lower activated clotting time value in these patients may be safe.
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Anesthesia and analgesia · Apr 2000
Sequencing cases in the operating room: predicting whether one surgical case will last longer than another.
A microscope will be used for the first case of the day in operating room (OR) 1 and then may be used in the second case of the day by a different surgeon in a different OR, OR 2. Provided that the probability is reasonably high that the first case of the day in OR 2 will last longer than the first case in OR 1, the OR manager can be confident in scheduling the microscope to be used by both surgeons on the same day. The OR manager can use statistical decision theory to sequence cases to decrease the impact of limitations in equipment or personnel on case scheduling. This increases utilization of both the capital equipment and OR time. In this study, we derived equations that can be programmed into a surgical services information system to reliably estimate the probability that one case will have a longer duration than another. We confirmed the accuracy of our method by using actual case duration data. ⋯ Our statistical method uses historical case duration data from an operating room information system to estimate the actual probability to within 1.5% that the second case of a pair will last longer than the first case of a pair.