Anesthesia and analgesia
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Anesthesia and analgesia · Aug 1995
Randomized Controlled Trial Clinical TrialThe optimal distance that a multiorifice epidural catheter should be threaded into the epidural space.
Complications can occur during epidural placement for women in labor. As many as 23% of epidural anesthetics may not provide satisfactory analgesia. The cause of this may be technical. ⋯ Fifteen minutes later, the adequacy of the analgesia was assessed by a blinded observer. We found that catheter insertion to a depth of 7 cm was associated with the highest rate of insertion complications while insertion to a depth of 5 cm was associated with the highest incidence of satisfactory analgesia. For women in labor who require continuous lumbar epidural anesthesia, we recommend threading a multiorifice epidural catheter 5 cm into the epidural space.
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Anesthesia and analgesia · Aug 1995
Randomized Controlled Trial Comparative Study Clinical TrialThe use of the laryngeal mask airway in children with bronchopulmonary dysplasia.
Airway maintenance with the laryngeal mask airway (LMA) was evaluated and compared to the endotracheal (ET) tube in 27 former premature infants and children with bronchopulmonary dysplasia (BPD) during second stage open-sky vitrectomy. The children were randomly assigned to a study group and anesthetized with halothane in N2O:O2. The airway was maintained with the LMA (n = 13) or the ET tube (n = 14). ⋯ The incidence of coughing, with and without desaturation, wheezing, and hoarseness in the postoperative period was higher in the ET tube group. Awakening, after discontinuation of the anesthetic (P < 0.01) was more rapid, and home discharge time (P < 0.002) was shorter in the LMA group (P < 0.0025), although our study design could not isolate the use of the LMA as the factor responsible for this. This study in patients with mild chronic lung disease demonstrated that the LMA can maintain a satisfactory airway during minor surgical procedures in children with bronchopulmonary dysplasia and result in fewer respiratory adverse effects than with the ET tube.
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Anesthesia and analgesia · Aug 1995
Comparative StudyComparison of the effects of halothane, isoflurane, and sevoflurane on atrioventricular conduction times in pentobarbital-anesthetized dogs.
It is not known how sevoflurane affects the cardiac conduction system. We compared the effects of halothane, isoflurance, and sevoflurane on specialized atrioventricular (AV) conduction times in eight pentobarbital-anesthetized dogs. AV conduction times with three inhaled anesthetics at end-tidal concentrations of 1 and 2 minimum alveolar anesthetic concentration (MAC), were measured by His-bundle electrocardiography during both sinus rhythm and right atrial pacing at a slightly higher rate than sinus one. ⋯ No significant difference in AV conduction times was observed between isoflurane and sevoflurane. Heart rate during sinus rhythm remained unchanged despite a decrease in arterial pressure with three inhaled anesthetics. The property of sevoflurane and isoflurane which does not affect the cardiac conduction system may be important in the stability of the cardiac rhythm during anesthesia with these drugs.
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Anesthesia and analgesia · Aug 1995
Large tidal volume ventilation does not improve oxygenation in morbidly obese patients during anesthesia.
Eight morbidly obese patients (body mass index [BMI] = 46) were studied during general anesthesia and controlled mechanical ventilation. To evaluate the effect of large tidal volume ventilation on oxygenation and ventilation, the baseline 13 mL/kg tidal volume (VT) (calculated by the ideal body weight) was increased in 3 mL/kg volume increments to 22 mL/kg, while ventilatory rate (RR) and inspiratory time (TI) were kept constant. Each volume increment was maintained for 15 min. ⋯ Peak inspiratory airway pressure (Ppeak), end-inspiratory airway pressure (Pplateau), and compliance of the respiratory system (CRS) were recorded using the Capnomac Ultima (Datex, Helsinki, Finland) on-line respiratory monitor. Increasing tidal volumes to 22 mL/kg increased the recorded Ppeak (26.3 +/- 4.1 vs 37.9 +/- 3.2 cm H2O, P < 0.008), Pplateau (21.5 +/- 3.6 vs 27.7 +/- 4.3 cm H2O, P < 0.01), and CRS (39.8 +/- 7.7 vs 48.5 +/- 8.3 mL/cm H2O) significantly without improving arterial oxygen tension and resulted in severe hypocapnia. Since changes in arterial oxygenation were small and not statistically significant, mechanical ventilation of morbidly obese patients with large VTS seems to offer no advantage to smaller (13 mL/kg ideal body weight) VTS.
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Anesthesia and analgesia · Aug 1995
The effect of changing end-expiratory pressure on respiratory system mechanics in open- and closed-chest anesthetized, paralyzed patients.
The decrease in functional residual capacity (FRC) with anesthesia may cause lung volume to decrease below closing volume, thereby impairing oxygenation. Increasing end-expiratory pressure (EEP) reexpands atelectatic areas in anesthetized, ventilated patients, but its effect on pulmonary mechanics is less well understood. We studied the effect of varying EEP on the mechanical behavior of the respiratory system in patients undergoing either closed (Group 1) or open-chest (Group 2) surgical procedures. ⋯ The magnitudes of RRS and RL were similar in both groups of subjects and in each group these quantities decreased with increases in EEP. Dynamic EL responded differently to changes in EEP in subjects with open-chest and closed-chest procedures. We attribute this difference to overdistension of the remaining ventilable lung tissue at all levels of EEP in open-chest patients.