Anesthesia and analgesia
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Comparative Study Clinical TrialArterial oxygenation and shunt fraction during one-lung ventilation: a comparison of isoflurane and sevoflurane.
The aim of this study was to evaluate the effect of isoflurane and sevoflurane on oxygenation and shunt fraction during one-lung ventilation (OLV). Twenty patients undergoing lobectomy for lung cancer and scheduled for long-term OLV were enrolled in this study. Patients were allocated to treatment with either isoflurane or sevoflurane. Arterial oxygenation, shunt fraction, and hemodynamics were evaluated at the end of two-lung ventilation; 20 min after the initiation of OLV; 20 min after the application of 4-cm positive end-expiratory pressure (PEEP) to the dependent lung; 20 min after 8-cm PEEP; and 20 min after the conversion from OLV to two-lung ventilation. There was no significant difference between isoflurane and sevoflurane with regard to oxygenation, shunt fraction, or hemodynamics during OLV. PaO2 values after the application of 4-cm PEEP increased from 131.1 +/- 11.8 mm Hg to 190.6 +/- 22.9 mm Hg in the isoflurane group (P < 0.05) and from 127.2 +/- 14.3 mm Hg to 192.4 +/- 26.9 mm Hg in the sevoflurane group (P < 0.05). The selection of either isoflurane or sevoflurane for OLV was made without regard to arterial oxygenation and shunt fraction. PEEP application to the dependent lung is useful for improving oxygenation during OLV, but 8-cm PEEP had no added effect compared with 4-cm PEEP. ⋯ We compared the effects of isoflurane and sevoflurane on oxygenation, hemodynamics, and shunt fraction during one-lung ventilation in 20 patients undergoing scheduled lobectomy for lung cancer. There was no significant difference between isoflurane and sevoflurane with regard to oxygenation, shunt fraction, and hemodynamics during one-lung ventilation. The application of 4-cm positive end-expiratory pressure increased the partial pressure of arterial oxygen during one-lung ventilation.
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Clinical TrialAdding ketamine in a multimodal patient-controlled epidural regimen reduces postoperative pain and analgesic consumption.
We designed this double-blind study to evaluate the effect of adding small-dose ketamine in a multimodal regimen of postoperative patient-controlled epidural analgesia (PCEA). Ninety-one patients, ASA physical status I-III, undergoing major surgery, received a standardized general anesthesia and epidural catheterization in an appropriate intervertebral space after surgery. A PCEA device was programmed to deliver a regimen of morphine 0.02 mg/mL, bupivacaine 0.8 mg/mL, and epinephrine 4 microg/mL, with the addition of ketamine 0.4 mg/mL (ketamine, n = 45) or without (control, n = 46). The mean visual analog pain scale (VAS) scores during cough or movement for the first 3 days after surgery were higher in the control group than in the ketamine group (P < 0.05), whereas the mean VAS score at rest for the first 2 days were higher in the control group than in the ketamine group (P < 0.05). Furthermore, patients in the control group consumed more multimodal analgesics than patients in the ketamine group for the first 2 days (P < 0.05). The sedation scores and the incidence of side effects (pruritus, nausea, emesis, sleep deprivation, motor block, and respiration depression) were similar between the two groups. We conclude that adding ketamine 0.4 mg/mL in a multimodal PCEA regimen provides better postoperative pain relief and decreases consumption of analgesics. ⋯ Many studies have evaluated one or a combination of two analgesics for postoperative pain control, but few have examined a multimodal approach using three or four different epidural analgesics. This study demonstrates an additive analgesic effect when ketamine is added to a multimodal analgesic treatment.
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Clinical TrialThe combination of epinephrine and isoproterenol as a simulated epidural test dose in isoflurane-anesthetized adults.
During isoflurane anesthesia, an epinephrine-containing test dose produces unreliable heart rate (HR) responses with a high incidence of hypertension, whereas an isoproterenol-containing test dose results in a high incidence of hypotension. We designed this study to determine whether different combination doses of epinephrine and isoproterenol produce reliable HR changes without overt fluctuations of systolic blood pressure (SBP). Seventy-five healthy patients were anesthetized with 1% end-tidal isoflurane after endotracheal intubation and randomized to one of five groups (n = 15 each) according to the combination dose given i.v.: epinephrine 15 microg, epinephrine 15 microg + isoproterenol 1.5 microg, epinephrine 7.5 microg + isoproterenol 3 microg, isoproterenol 3 microg, and saline. HR and SBP were measured at 20-s intervals for 4 min after injection. Based on the conventional HR criterion (positive if > or = 20 bpm increase), the epinephrine 15 microg + isoproterenol 1.5 microg, the epinephrine 7.5 microg + isoproterenol 3 microg, and the isoproterenol 3 microg groups yielded 100% sensitivities, specificities, and positive and negative predictive values, whereas all groups yielded 100% efficacy according to the modified HR criterion (positive if > or = 10 bpm increase). Four (27%) and three patients (20%) in the epinephrine 15 microg and the epinephrine 15 microg + isoproterenol 1.5 microg groups, respectively, developed systolic hypertension (SBP > or = 180 mm Hg), whereas four (27%) patients in the isoproterenol 3 microg group developed systolic hypotension (SBP < or = 80% of the preinjection value). We conclude that epinephrine 7.5 microg + isoproterenol 3 microg provides the most reliable HR changes with the least SBP fluctuations. ⋯ To test whether an epidural catheter may be in a blood vessel, various vasoactive drugs are administered during general anesthesia. The authors found that the combination of epinephrine 7.5 microg and isoproterenol 3 microg produced the most reliable heart rate changes with minimal blood pressure fluctuations.
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Anesthesia and analgesia · Jun 1998
Randomized Controlled Trial Comparative Study Clinical TrialBronchial mucus transport velocity in paralyzed anesthetized patients: a comparison of the laryngeal mask airway and cuffed tracheal tube.
We compared bronchial mucus transport velocity (BTV), an index of mucociliary clearance, between the laryngeal mask airway (LMA) and the tracheal tube (TT). Forty patients were studied during propofol anesthesia and muscle relaxation with rocuronium. BTV was measured 10 and 60 min after insertion of the airway device by fiberoptic observation of the movement of methylene blue dye injected onto the dorsal surface of the left main bronchus. BTV for the LMA was similar at 10 and 60 min (13.9 +/- 2.0 and 13.6 +/- 2.1 mm/min, respectively). BTV for the TT was significantly faster at 10 min that at 60 min (13.0 +/- 1.4 vs 6.9 +/- 1.2 mm/min, respectively; P < 0.00001). BTV was similar for both devices at 10 min (TT 13.0 +/- 1.4 mm/min versus LMA 13.9 +/- 2.0 mm/min), but was significantly faster for the LMA than for the TT at 60 min (LMA 13.6 +/- 2.1 mm/min versus TT 6.9 +/- 1.2 mm/min; P < 0.00001). We conclude that the LMA impedes mucociliary clearance less than the TT in anesthetized patients. This may have implications for reducing the risk of retention of secretions, atelectasis, and pulmonary infection. ⋯ This study compares bronchial mucus transport velocity, an index of mucociliary clearance, in anesthetized patients between two airway devices, the cuffed tracheal tube and the laryngeal mask airway. We have shown that the laryngeal mask airway impairs mucociliary clearance less than the tracheal tube. This may have implications for reducing the risk of retention of secretions, atelectasis, and pulmonary infection.
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Anesthesia and analgesia · Jun 1998
Comparative StudyTesting internal consistency and construct validity during evaluation of performance in a patient simulator.
The primary goal of this study was to test the items in a rating system developed to evaluate anesthesiologists' performance in a simulated patient environment. A secondary goal was to determine whether the test scores could discriminate between resident and staff anesthesiologists. Two 5-item clinical scenarios included patient evaluation and induction and maintenance of anesthesia. Rating scales were no response to the problem (score = 0), compensating intervention (score = 1), and corrective treatment (score = 2). Internal consistency was estimated using Cronbach's coefficient alpha. Scores between groups were compared using the Cochran-Mantel-Haenszel test. Subjects consisted of 8 anesthesiology residents and 17 university clinical faculty. The Cronbach's coefficient alpha was 0.27 for Scenario A and 0.28 for Scenario B. Two items in each scenario markedly decreased internal consistency. When these four items were eliminated, Cronbach's coefficient alpha for the remaining six items was 0.66. Faculty anesthesiologists scored higher than residents on all six items (P < 0.001). A patient simulator-based evaluation process with acceptable reliability was developed. ⋯ The reliability of anesthesia clinical performance in a patient simulation environment was assessed in this study. Of 10 items, 4 were poor in the evaluation process. When these items were removed, the reliability of the instrument improved to a level consistent with other studies. Because faculty scored higher than resident anesthesiologists, the instrument also showed discriminant validity.