Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1998
Comparative Study Clinical TrialComparison of plasma lidocaine concentrations after injection of a fixed small volume in the stellate ganglion, the lumbar epidural space, or a single intercostal nerve.
We measured the plasma lidocaine concentrations after stellate ganglion block (SGB) and compared them with those after intercostal nerve block (ICNB) and epidural block (EB) using identical doses of lidocaine. Thirty patients undergoing SGB (n = 10), ICNB (n = 10), or EB (n = 10) in our pain clinic participated in this study. Six milliliters of 1% lidocaine was used for all nerve blocks. SGB was performed at the C6 transverse process, ICNB was performed on a single intercostal nerve, and epidural lidocaine was injected through the lumbar epidural catheter. After drug administration, venous blood samples were taken from an indwelling catheter in the arm every minute for the first 10 min and 15, 20, 30, 45, and 60 min thereafter. Plasma lidocaine concentrations were measured by using an enzyme immunoassay method. The SGB group showed significantly higher peak plasma lidocaine concentrations than other groups (SGB 1.65 +/- 0.21 microgram/mL, ICNB 0.89 +/- 0.12 microgram/mL, EB 0.91 +/- 0.19 microgram/mL; P < 0.01). The SGB group reached peak levels significantly faster than the other groups (SGB 3.4 +/- 1.0 min, ICNB 7.9 +/- 1.5 min, EB 6.9 +/- 0.7 min; P < 0.01). We conclude that the plasma lidocaine concentrations after SGB were higher than those after ICNB and EB when using small, equal doses of lidocaine. The high and rapid peak plasma lidocaine concentrations after SGB are probably related to the high vascularity of the injection site. ⋯ Higher plasma concentrations of local anesthetics are reportedly obtained after multiple intercostal nerves blocks compared with those after other types of nerve blocks. Our results, however, showed that the peak plasma concentrations after stellate ganglion block were higher and faster than those after a single intercostal nerve block.
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Anesthesia and analgesia · Jul 1998
Practice patterns in managing the difficult airway by anesthesiologists in the United States.
Despite the availability of several techniques and devices for the management of the difficult airway, little information has been published regarding the prevalence of their use by anesthesiologists in the United States. To determine current practice patterns, we surveyed clinicians using a questionnaire consisting of 14 difficult airway scenarios. Anesthesiologists were requested to indicate their likely approach to anesthetic induction (e.g., awake but sedated, general anesthesia with spontaneous ventilation, general anesthesia with apnea after assuring a patent airway, or general anesthesia with apnea) and the primary device they would use to intubate (e.g., direct laryngoscopy [DL], flexible fiberoptic bronchoscope [FOB], rigid fiberoptic device, surgical airway, retrograde intubation kit, laryngeal mask airway, gum elastic bougie, or Combitube). The availability of these devices was also determined (in room at all times, available "stat," available if arranged preoperatively, or not available). The survey was mailed to 1000 randomly chosen active members of the American Society of Anesthesiologists. Second and third surveys were mailed to non responders. Four hundred seventy-two completed surveys were returned. Responses by demographic groups were compared by using chi 2 analysis. DL and FOB-aided tracheal intubation techniques were chosen for most cases by most anesthesiologists (P < 0.05). Anesthesiologists with > 10 yr of clinical experience and those older than 55 yr of age preferred DL with apneic conditions (P < 0.05). Anesthesiologists who had attended workshops within the last 5 yr had greater availability of retrograde guidewire equipment and FOBs (P < 0.05). There was little use of newer alternative airway devices. ⋯ Although the teaching of alternative methods of securing a difficult airway has become ubiquitous, most anesthesiologists rely on direct laryngoscopy and fiberoptic-aided intubation in most clinical circumstances. Although workshops in the management of the difficult airway may have resulted in increased use of the fiberoptic bronchoscope and the availability of retrograde guidewire intubation equipment, other devices have not enjoyed such an increase.
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Anesthesia and analgesia · Jul 1998
Clinical TrialOvernight hospitalization after radical prostatectomy: the impact of two clinical pathways on patient satisfaction, length of hospitalization, and morbidity.
Changes in health care have prompted efforts to reduce length of hospitalization while maintaining quality care. Therefore, we evaluated short-term outcomes after radical retropubic prostatectomy on 100 consecutive men undergoing surgery for clinically localized prostate cancer performed under epidural anesthesia followed by epidural morphine or combined with spinal anesthesia using bupivacaine and fentanyl (25 micrograms) and followed by i.m. methadone (10-20 mg). All patients received oral acetaminophen and ibuprofen beginning 4 h after surgery. Length of hospital stay, responses to written satisfaction survey, postoperative morbidity and readmission to the hospital were recorded. Using either pathway, 83% of the patients were discharged after one night in the hospital. The mean hospital stay was 1.34 +/- 1.10 and 1.28 +/- 1.0 days, respectively. Although three men were rehospitalized, it was not because of the early discharge. More than 95% of patients were satisfied with pain control, and patients discharged after one night were not more likely to be dissatisfied than patients hospitalized longer. ⋯ Both clinical pathways provide excellent anesthesia and analgesia and allow discharge 1 day after radical retropubic prostatectomy. Shortened hospital stay does not increase patient dissatisfaction or add to postoperative morbidity. Patients undergoing other pelvic and abdominal operations may also derive similar benefits using these pathways.
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Anesthesia and analgesia · Jul 1998
Comparative StudyThe hemodynamic effects of hypoxemia in anesthetized pigs: a comparison between right heart catheter and echocardiography.
During hypoxemia, hypoxic pulmonary vasoconstriction and tachycardia are often observed in association with increases in pulmonary artery pressure and cardiac output. Nevertheless, the hemodynamic consequences of hypoxemia have never been evaluated by echocardiography and simultaneously compared with invasive hemodynamic variables. Fourteen open-chest, anesthetized piglets (weight 29-36 kg) were submitted to progressive hypoxemia and reoxygenation. Usual invasive hemodynamic variables were obtained from peripheral and central heart catheters. Direct epicardial echocardiography was used to measure right and left ventricular areas on a short-axis view at mid-papillary level. The mean pulmonary artery pressure (MPAP) increased with pulmonary vascular resistance in a dose-related manner as the fraction of inspired oxygen (FIO2) declined from 0.5 to 0.12. The MPAP correlated with right ventricular end-diastolic area (RVEDA) only at FIO2 0.08. There was a 49% reduction in left ventricular end systolic wall stress (LVESWS) between FIO2 0.5 and 0.08. Left ventricular ejection fraction area (LVEFA) increased by 33% above baseline and correlated with the decrease in LVESWS. No correlation was observed between left ventricular end-diastolic area and pulmonary artery occlusion pressure or left atrial pressure and between cardiac output and LVEFA. Systemic vascular resistance underestimates the magnitude of changes in LVESWS but overestimates the afterload compared with LVESWS. This study demonstrates that, for the lowest FIO2 (0.08), changes in MPAP correlated with changes in RVEDA but not in pulmonary vascular resistance. Moreover, LVESWS decreases significantly in a dose-related manner under progressive hypoxemia and normalizes immediately after reoxygenation. This study also shows that, under hypoxemic conditions, echocardiography enhances understanding of hemodynamic changes compared with right heart catheterization alone. ⋯ Acute hypoxemia in pigs is responsible for pulmonary vasoconstriction-induced pulmonary hypertension (which is restricted by the right ventricular failure), as well as a PaO2-dependent decrease in left ventricular afterload. These changes are better displayed by echocardiography than by right heart catheter.
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Anesthesia and analgesia · Jul 1998
Clinical TrialLateral approach to the sciatic nerve in the popliteal fossa.
We describe a modification of the sciatic nerve (SN) block in the popliteal fossa through the lateral approach. After a brief anatomic study using previously reported landmarks, we propose a new needle orientation associated with a double injection technique after identification of the tibial and the common peroneal nerve. Thirty-four patients undergoing ankle or foot surgery were enrolled in this study. With patients in the supine position, the upper edge of the patella and the groove between the posterior border of the vastus lateralis and the anterior border of the tendon of the biceps femoris were identified. The needle was directed posteriorly with a 20-30 degrees angle relative to the horizontal plane and slightly caudal. Both nerves were individually located with a nerve stimulator and blocked with a mixture of lidocaine-bupivacaine and clonidine. In all but one case, the two nerves were easily located, and no vascular puncture was evident. Effective analgesia was obtained for a minimum of 15 h (first analgesic demand). We conclude that this technique, with a modified direction of the needle and a double stimulation, provides a very high rate of success for SN blockade in the popliteal fossa. ⋯ We describe a new lateral approach to the sciatic nerve in the popliteal fossa. The needle was directed caudad and posteriorly while seeking with a nerve stimulator for the tibial and the peroneal nerves, which were blocked separately. This technique was very successful.