Anesthesia and analgesia
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Anesthesia and analgesia · Nov 1998
Randomized Controlled Trial Clinical TrialCough during emergence from isoflurane anesthesia.
We evaluated the effects of smoking history and albuterol treatment on the amplitude and frequency of cough during emergence from anesthesia. Before induction of anesthesia, 68 patients were randomized to receive two puffs of a placebo or two puffs of albuterol via a metered dose inhaler. Anesthesia was then induced with thiopental, fentanyl, and succinylcholine. The patients' tracheas were intubated with an 8.0 mm-endotracheal tube, and isoflurane administration was initiated. At the end of surgery, isoflurane was discontinued, and the pressure in the endotracheal tube cuff was monitored via the pilot balloon while the end-tidal isoflurane concentration was recorded. Of the 68 patients, 52 coughed before responding to command, but the incidence did not differ between smokers and nonsmokers (33 of 43 vs 19 of 25), nor did it differ between albuterol-treated and untreated patients. There was no difference in the frequency or amplitude of coughs between smokers and nonsmokers, nor did albuterol affect either variable. The mean end-tidal concentration at which cough first occurred was 0.30%+/-0.02%, and only 5% of patients coughed at values >0.6%. We conclude that 1) cough is frequent during emergence; 2) smoking does not affect emergence cough; 3) albuterol treatment does not affect emergence cough; and 4) patients are unlikely to cough at end-tidal values of isoflurane >0.6%. ⋯ Most patients cough as they awaken from general anesthesia given via an endotracheal tube. In our study population, cough was frequent but generally did not occur until the end-tidal concentration of isoflurane was <0.6%. Smokers were no more likely to cough than nonsmokers, and the beta-adrenergic agonist albuterol did not prevent cough.
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Anesthesia and analgesia · Nov 1998
Clinical TrialIncreased anticoagulation during cardiopulmonary bypass by prostaglandin E1.
Prostaglandin E1 (PGE1) inhibits tissue factor/factor VIIa-dependent thrombin formation and platelet procoagulant activity. These pathways may trigger thrombin generation during cardiopulmonary bypass (CPB). We hypothesized that the therapeutic combination of PGE1 and heparin increases the degree of anticoagulation as measured by reduced thrombin generation during CPB. Patients undergoing primary coronary artery bypass grafting using CPB were anticoagulated with unfractionated porcine heparin and 12.5 ng x kg(-1) x min(-1) PGE1 (n = 20) or placebo (n = 20). Plasma markers that reflect thrombin generation (prothrombin fragment F1+2, thrombin-antithrombin complex) were determined, and postoperative bleeding was documented. Thrombin generation gradually increased in both groups during and after CPB but was lower in the PGE1 group. After CPB, the difference between mean levels of prothrombin fragment F1+2 was 1.9 nmol/L (95% confidence interval for difference 1.1 to 2.8; P = 0.001). The difference between mean levels of thrombin-antithrombin complex was 43.6 ng/mL (21.2 to 66.1; P = 0.001). A trend in reduced postoperative bleeding was observed in the PGE1 group with a difference of sample means of 183 mL (-5 to 371; P = 0.056). Adding PGE1 to unfractionated heparin enhances anticoagulation during CPB. The results suggest that reduced thrombin generation during surgery may decrease postoperative bleeding. ⋯ Cardiopulmonary bypass is associated with extensive thrombin generation even in the presence of clinically sufficient heparin anticoagulation. The addition of prostaglandin E1 to heparin enhances the degree of anticoagulation as measured by reduced thrombin formation during cardiopulmonary bypass.
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Anesthesia and analgesia · Nov 1998
Clinical TrialAssessment of oropharyngeal distance in children using magnetic resonance imaging.
Rational determination of oral airway size in children must account for the oropharyngeal length. We used magnetic resonance imaging (MRI) to measure the distance from the teeth/gums to the prevertebral pharyngeal space and created algorithms to predict this distance based on age, weight, and gender. After institutional review board approval, we reviewed 200 MRI head scans of children 0-17 yr old. Patient information, including midline distance from teeth/gums to prevertebral space (L1) and distance along a perpendicular line from L1 to the epiglottis tip (L2), was recorded. Two groups (Group 1 (n = 100) training group, Group 2 (n = 100) validation group) were then randomly selected from this sample. Predictive models created using Group 1 were tested using Group 2 as the sample group. Oropharyngeal distance was related to age, weight, and gender. A prediction equation using all data was estimated to determine the final model: predicted L1 = 5.51 + 0.25 (age [years]) -0.01 (age2) + 0.02 (weight [kg]) + 0.12 (male). We report equations to predict the oropharyngeal distance based on age, weight, and gender in children. The oral airway size will be 1-2 cm longer than these measurements to position the tooth/lip guard outside the lip. Variability in the distance to the epiglottis must be considered when selecting proper oral airway size for any child. This information will provide the foundation for a more rational determination of the proper oral airway size for infants and children. ⋯ Age, weight, and gender can be used to predict the length of the oropharynx in children as determined by midline sagittal magnetic resonance image of the airway. Prediction of this length will lead to a more rational determination of proper oral airway size for infants and children and, potentially, more effective airway management.
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Anesthesia and analgesia · Nov 1998
The effect of fibrin glue patch in an in vitro model of postdural puncture leakage.
We studied the possibility of stopping a continuing transdural leakage with fibrin glue, a biologic adhesive, in an in vitro model. The model was made by sealing the bottom of a tube filled with saline to a height of 50 cm with a human lyophilized dural specimen. Dural punctures were performed with a 17-gauge Tuohy needle. The needle was then withdrawn, and 0.8 mL of fibrin glue was injected through the same needle to seal the defect. The column was refilled 3 min after sealing. The pressure in the intrathecal chamber was measured during the procedure. Macroscopic and microscopic histological studies of the dura and the fibrin plug were performed. In the five cases studied, the leak was sealed by the fibrin plug at closing pressures of 25-35 cm H2O, and no further leakage was detected after refilling. The dural specimens showed a fibrin glue plug stuck at the edges of the hole. We conclude that fibrin glue stops leakage of fluid from dural holes created by a 17-gauge Tuohy needle in an in vitro pressurized model. ⋯ We explored the possibility of repairing a cerebrospinal fluid leak produced by an accidental dural puncture during epidural anesthesia by percutaneously injecting tissue adhesive in vitro. This technique seems promising for the prophylaxis and treatment of the headache associated with this leakage but requires further study in vivo.
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The National Institute of Occupational Safety and Health (NIOSH) has established recommended exposure limits of 25 parts per million (ppm) as a time-weighted average for nitrous oxide and a ceiling of 2 ppm for volatile anesthetics. We quantified exposure of postanesthetic nurses to exhaled anesthetic gases. This study was conducted in the postanesthesia care unit (PACU) of a medium-sized hospital. PACU air exchanges averaged 8 vol/h; however, much of this air was recirculated. We evaluated 50 adults anesthetized with either isoflurane (n = 19) or desflurane (n = 31). Roughly half the patients were tracheally extubated in the operating room, whereas the others were extubated just after admission to the PACU. Exhaled anesthetic gases were sampled through a 20-m hose attached to the participating nurses' shoulders (breathing zone). We also evaluated nursing exposure to exhaled anesthetic gases during recovery of 15 patients who had been anesthetized with nitrous oxide. Exposure was quantified with lapel dosimeters. Anesthetic and recovery durations were each approximately 1 h, with most patients being tracheally extubated in the PACU. Breathing-zone anesthetic concentrations in the patients given isoflurane exceeded NIOSH recommendations in 37% of the patients, representing 12% of recovery time. Breathing-zone anesthetic concentrations in the patients given desflurane, however, exceeded NIOSH limits in 87% of the patients, representing 49% of recovery time. Altogether, noncompliant episodes were detected in 68% of these patients, representing 35% of the entire recovery duration. Breathing-zone anesthetic concentrations in the patients given nitrous oxide exceeded NIOSH limits in 53% of the patients. Our data suggest that postoperative nurses' exposure to exhaled anesthetic gases exceeds NIOSH limits under some circumstances. ⋯ Some epidemiological evidence suggests that exposure to waste anesthetic gases may be associated with reproductive toxicity. Accordingly, the National Institute of Occupational Safety and Health has established recommended exposure limits for nitrous oxide and volatile anesthetics. Our data suggest that exposure of healthcare personnel may exceed recommended levels in poorly ventilated postanesthesia care units.