Michael L. Nessly

Postoperative epidural morphine is safe on surgical wards.

The use of epidural morphine for postoperative analgesia outside of intensive care units remains controversial. In this report our anesthesiology-based acute pain service documents experience with 1,106 consecutive postoperative patients treated with epidural morphine on regular surgical wards. This

Epidural and intravenous fentanyl infusions are clinically equivalent after knee surgery

The management of postoperative pain with continuous epidural fentanyl infusion was compared with continuous intravenous fentanyl infusion. In a randomized, double-blind protocol we prospectively studied 20 patients undergoing repair of the anterior cruciate ligament of the knee. The quality of analgesia and the incidence of side effects were documented. Compared with patients receiving continuous intravenous fentanyl infusion, at 18 h postoperatively patients given continuous epidural fentanyl infusion reported similar pain scores both at rest (22 ± 25 vs 27 ± 21 P = 0.52) and with ambulation (59 ± 18 vs 56 ± 22, P = 0.82). Plasma fentanyl levels were 1.8 ± 0.4 and 1.7 ± 0.4 ng/m.L (P = 0.91) for the intravenous and epidural groups, respectively. There were no significant differences in the incidence of nausea, pruritus, or urinary retention. There was no respiratory depression in either group. We conclude that when compared with continuous intravenous fentanyl infusion, continuous epidural fentanyl infusion offers no clinical advantages for the management of postoperative pain after knee surgery.

Spinal needle determinants of rate of transdural fluid leak.

Using a new in vitro model and samples of human dura, a number of factors related to spinal needle design and use were examined with respect to their effects on the rate of transdural fluid leak. These included needle size, bevel design, bevel orientation, and angle of approach. Using 25-gauge Quincke needles, a 30 degree approach caused a rate of leak across the dura significantly less than those following 60 degree and 90 degree approaches. A significant increase in leak rate was found with 22-gauge Quincke needles when the bevels were oriented so as to be perpendicular rather than parallel to the long axis of the dura. Also, 22-gauge Whitacre needles caused significantly less leak than did 22-gauge Quincke needles, and 25-gauge Quincke needles produced significantly less leak than 22-gauge Quincke needles. If human dura behaves in vivo as it does in this in vitro model, it would be advantageous to perform lumbar puncture using oblique approaches and small needles with conical tips.

A Randomized Study of Carbon Dioxide Management during Hypothermic Cardiopulmonary Bypass

Eighty-six patients undergoing coronary artery bypass graft (n = 63) or intracardiac (n = 23) surgery were randomly assigned with respect to the target value for PaCO2 during cardiopulmonary bypass. In 44 patients the target PaCO2 was 40 mmHg, measured at the standard electrode temperature of 37 degrees C, while in 42 patients the target PaCO2 was 40 mmHg, corrected to the patients rectal temperature (lowest value reached: mean 30.1, SD 1.9 degrees C). Other salient features of bypass management include use of bubble oxygenators without arterial filtration, flows of 1.8-2.4 l.min-1.m-2, mean hematocrit of 23%, and mean arterial blood pressure of approximately 70 mmHg, achieved by infusion of phenylephrine or sodium nitroprusside. Neuropsychologic function was assessed with series of tests administered on the day prior to surgery, just before discharge from the hospital (mean 8.0, SD 5.8 days postoperatively, n = 82), and again 7 months later (mean 220.7, SD 54.4 days postoperatively, n = 75). The scores at 8 days showed wide variability and generalized impairment unrelated to the PaCO2 group or to hypotension during cardiopulmonary bypass. At 7 months no significant difference was observed in neuropsychologic performance between the PaCO2 groups. Regarding cardiac outcome, there were no significant differences between groups in the appearance of new Q-waves on the electrocardiogram, the postoperative creatine kinase-MB fraction, the need for inotropic or intraaortic balloon pump support, or the length of postoperative ventilation or intensive care unit stay. These findings support the hypothesis that CO2 management during cardiopulmonary bypass at moderate hypothermia has no clinically significant effect on either neurobehavioral or cardiac outcome.

Comparison of desflurane with propofol in outpatients undergoing peripheral orthopedic surgery

This study was undertaken to compare desflurane with propofol anesthesia in outpatients undergoing peripheral orthopedic surgery. Data were combined from two institutions participating in a multicenter study. Ninety-one patients, ASA physical status I or II, were each randomly assigned to one of four groups. After administration of fentanyl (2 micrograms/kg) and d-tubocurarine (3 mg), intravenous propofol was administered to induce anesthesia in groups I and II and desflurane in groups III and IV. Maintenance was provided by desflurane/N2O in groups I and III, propofol/N2O in group II, and desflurane/O2 in group IV. Emergence and recovery variables, psychometric test results, and side effects were recorded by observers unaware of the experimental treatment. Patients in group II experienced less nausea than other groups (P = 0.002) despite this group having required more intraoperative fentanyl supplementation than groups III and IV (P = 0.01). Time to emergence, discharge, and psychometric test results were similar in all groups. Desflurane appears to be comparable with propofol as an outpatient anesthetic, facilitating rapid recovery and discharge home.

Paralyzed with pain: the need for education

This report surveyed the pharmacologic knowledge of the physician housestaff and intensive care nurses regarding the analgesic and anxiolytic effects of narcotics, benzodiazepines and neuromuscular blockers. The results demonstrated a commonly held misconception that muscular paralysis is a calm and painless state. The authors instituted an educational program stressing the need for analgesic and anxiolytic medications in conjunction with paralytic agents.

Epidural morphine provides greater pain relief than patient-controlled intravenous morphine following cholecystectomy

The management of postoperative pain today increasingly involves use of either epidural narcotics or intravenous (IV) patient-controlled analgesia (PCA) (1,2). Neither technique is without risk or undesirable side effects, such as pruritus, nausea, and urinary retention. Whereas epidural morphine requires vigilance to detect occasional respiratory depression (2), IV PCA requires expensive delivery systems subject to mechanical failure or human error (3). The few studies that have compared epidural to IV PCA morphine for the management of postoperative pain are limited because only a single dose of epidural narcotic was administered (4-6). Following lower extremity surgery, we found that epidural morphine provided greater patient comfort both at rest and with ambulation (7). Epidural morphine may thus be particularly advantageous to facilitate early joint mobilization. Postoperative pain following upper abdominal surgery is often increased with coughing. This effect may cause splinting and a reluctance to breathe deeply (8). The purpose of this report is to evaluate both the quality of analgesia and the incidence of side effects resulting from the management of postoperative pain with either epidural or IV PCA morphine in patients following cholecystectomy.

Vaso-vagal reactions in an ambulatory surgery center

This prospective study was undertaken to determine the incidence and factors predisposing to vaso-vagal reactions during venous cannulation in an ambulatory surgery population. In 141 ambulatory surgery patients, signs and symptoms of a reaction together with mean arterial pressure and heart rate were recorded at 1-min intervals during and for 6 min after venous cannulation. Overall, 10.6% of patients were symptomatic (95% confidence interval [CI] 6%-17%). The incidence was 16.6% (95% CI 8.4%-24.9%) in patients < or = 40 yr and 33.3% (95% CI 6.7%-60.0%) with a prior fainting history. Young age, duration or number of attempts at venous cannulation, and fainting history were independently associated with increased risk of a reaction (P < 0.03-0.004 by multiple repression analysis). Minimum mean arterial pressure was less in symptomatic patients than in those who were asymptomatic (58 mm Hg +/- 11.3 SD versus 82 mm Hg +/- 14.3 SD, P < 0.0001). We conclude that reactions occur commonly, particularly in the young or in patients with a history of fainting. Reactions are typically associated with significant hypotension that may require treatment.

Methodology for three-dimensional reconstruction of the left ventricle from transesophageal echocardiograms☆

A technique is presented for three-dimensional (3-D) reconstruction of the left-ventricular endocardial surface from multiplanar transesophageal echocardiograms, using both commercial software and investigator written Fortran programs for Intel 80286 and 80386 microcomputers. The approach provides quantitative global and regional cardiac performance measures and allows viewing the endocardial surface, at end-diastole and end-systole, from chosen perspectives. Anatomical landmarks are incorporated to aid in orientation. For regional calculation, the surface is divided into equal angular elements with each conceptually connected to the left-ventricular end-diastole centroid, forming a pyramidal volume element. This angular division automatically normalizes for heart size. The fractional change of these elements over the cardiac cycle provides a regional ejection fraction measure which is color-coded on the reconstructed endocardial surface. Composite perspective views, regional ejection fraction histograms and calculations of global end-diastolic, end-systolic, and stroke volumes, are all performed by the method.

Three-dimensional transesophageal echocardiography for depiction of regional left-ventricular performance: initial results and future directions

To assess the potential of a prototype transesophageal echocardiography probe for evaluating left-ventricular wall motion in three dimensions, we acquired images under anesthesia in 15 patients who had akinesia or dyskinesia and 8 patients who had normal function demonstrated on preoperative ventriculography. Shortaxis, oblique transgastric scans were obtained in 16 of the patients and four-chamber, long-axis oblique scans were obtained in 12 patients, with five patients (22%) yielding good-quality scans of both types. Off-line, we outlined the endocardial borders manually and used the outlines to make computer-generated three-dimensional models of the endocardial surfaces, color-tiled according to regional ejection fraction.Compared with contrast ventriculograms, the regional ejection fraction histograms derived from these models showed 86% concordance for detecting dyssynergy. However, the concordance between the ventriculograms and the color-tiled models in localizing the dyssynergy was only 67% overall. Uncertainty in rotational alignment between the reconstructions and the ventriculograms appeared to contribute to misreading the location of dyssynergy. In addition, the apical region appeared to have been missed in 8 (50%) of the shortaxis scans, whereas it was visualized in all long-axis scans.We conclude that three-dimensional analysis of the location, extent, and degree of left-ventricular dyssynergy is feasible from transesophageal echocardiograms and could have wide application in the study of regional ventricular function. However, improvements are necessary to enable the transducer to scan the cardiac apex more reliably from the short-axis viewpoint and to have a means for spatially orienting the images with respect to an external frame of reference.