Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 1998
Clinical TrialPredicting the size of a double-lumen endobronchial tube based on tracheal diameter.
We assessed whether using the tracheal diameter to predict the correct size of the left double-lumen endobronchial tube (DLT) could be used for our generally smaller sized Asian patients. Sixty-six consecutive adult patients under anesthesia for elective surgery requiring the use of a DLT were studied. The size of the left-sided DLT used was based on the width of patients' trachea measured from the preoperative posterior-anterior chest radiograph. The placement of the DLT was standardized and confirmed with fiberoptic bronchoscopy. The correct size of the DLT was the largest size tube inserted into the left bronchus with a small air leak detectable when the endobronchial cuff was deflated but not exceeding the recommended resting volume when inflated for lung isolation. Using this method of choosing our DLT, we found that an oversized DLT was often chosen especially among our female Asian patients. The overall positive predictive values for the male and female patients were 77.3% and 45.5%, respectively. We postulate that this could be due to our criteria for correct DLT size or that our local Asian patients, especially the females, were smaller and shorter. ⋯ This study assessed whether the correct double-lumen endobronchial tube size could be predicted from tracheal diameter measurements taken from the chest radiograph. We found that this method of choosing the double-lumen endobronchial tubes was not always reliable.
-
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.
-
Anesthesia and analgesia · Jul 1998
Tramadol reduces the sweating, vasoconstriction, and shivering thresholds.
The analgesic tramadol inhibits the neuronal reuptake of norepinephrine and 5-hydroxytryptamine, facilitates 5-hydroxytryptamine release, and activates mu-opioid receptors. Each of these actions is likely to influence thermoregulatory control. We therefore tested the hypothesis that tramadol inhibits thermoregulatory control. Eight volunteers were evaluated on four study days, on which they received no drugs, tramadol 125 mg, tramadol 250 mg, and tramadol 250 mg with naloxone, respectively. Skin and core temperatures were gradually increased until sweating was observed and then decreased until vasoconstriction and shivering were detected. The core temperature triggering each response defined its threshold. Tramadol decreased the sweating threshold by -1.03 +/- 0.67 degrees C microgram-1.mL (r2 = 0.90 +/- 0.12). Tramadol also decreased the vasoconstriction threshold by -3.0 +/- 4.0 degrees C microgram-1.mL (r2 = 0.94 +/- 0.98) and the shivering threshold by -4.2 +/- 4.0 degrees C microgram-1.mL(r2 = 0.98 +/- 0.98). The sweating to vasoconstriction interthreshold range nearly doubled from 0.3 +/- 0.4 degree C to 0.7 +/- 0.6 degree C during the administration of large-dose tramadol (P = 0.04). The addition of naloxone only partially reversed the thermoregulatory effects of tramadol. The thermoregulatory effects of tramadol thus most resemble those of midazolam, another drug that slightly decreases the thresholds triggering all three major autonomic thermoregulatory defenses. In this respect, both drugs reduce the "setpoint" rather than produce a generalized impairment of thermoregulatory control. Nonetheless, tramadol nearly doubled the interthreshold range at a concentration near 200 ng/mL. This indicates that tramadol slightly decreases the precision of thermoregulatory control in addition to reducing the setpoint. ⋯ The authors evaluated the effects of the analgesic tramadol on the three major thermoregulatory responses: sweating, vasoconstriction, and shivering. Tramadol had only slight thermoregulatory effects. Its use is thus unlikely to provoke hypothermia or to facilitate fever.
-
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.
-
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.