Keith P. Lewis

Cardiac Outcome after Peripheral Vascular Surgery: Comparison of General and Regional Anesthesia

Background Despite evidence that regional anesthesia may be associated with fewer perioperative complications than general anesthesia, most studies that have compared cardiac outcome after general or regional anesthesia alone have not shown major differences. This study examines the impact of anesthetic choice on cardiac outcome in patients undergoing peripheral vascular surgery who have a high likelihood of associated coronary artery disease. Methods Four hundred twenty‐three patients, between 1988 and 1991, were randomly assigned to receive general (n = 138), epidural (n = 149), or spinal anesthesia (n = 136) for femoral to distal artery bypass surgery. All patients were monitored with radial artery and pulmonary artery catheters. Postoperatively, patients were in a monitored setting for 48–72 h and had daily electrocardiograms for 4–5 days and creatine phosphokinase/isoenzymes every 8 h x 3, then daily for 4 days. Cardiac outcomes recorded were myocardial infarction, angina, and congestive heart failure. Results Baseline clinical characteristics were not different between anesthetic groups. Overall, the patient population included 86% who were diabetic, 69% with hypertension, 36% with a history of a prior myocardial infarction, and 41% with a history of smoking. Cardiovascular morbidity and overall mortality were not significantly different between groups when analyzed by either intention to treat or type of anesthesia received. In the intention to treat analysis, incidences of cardiac event or death for general, spinal, and epidural groups were 16.7%, 21.3%, and 15.4%, respectively. The absolute risk difference observed between general and all regional anesthesia groups for cardiac event or death was ‐1.6% (95% confidence interval ‐9.2%, 6.1%) This reflected a nonsignificant trend for lower risk of postoperative events with general anesthesia. Conclusions The choice of anesthesia, when delivered as described, does not significantly influence cardiac morbidity and overall mortality in patients undergoing peripheral vascular surgery.

Anesthesia type does not influence early graft patency or limb salvage rates of lower extremity arterial bypass

PURPOSE The effect of anesthesia type on 30-day graft patency and limb salvage rates was evaluated in patients who underwent femoral to distal artery bypass. METHODS Of 423 patients randomly assigned to receive general, spinal, or epidural anesthetic, 76 did not meet protocol standards and 32 had inadequate anesthesia. A chart review of the remaining 315 patients was undertaken to obtain surgical information not recorded in the original study. All patients were monitored with radial and pulmonary artery catheters. After surgery, patients were in a monitored setting for 48 to 72 hours and had graft function assessments hourly during the first 24 hours and then every 8 hours until discharge. RESULTS Fifty-one patients were lost to follow-up (15 general, 22 spinal, 14 epidural). Baseline clinical characteristics were similar for the three groups except prior carotid artery surgery, which was more common in the spinal group. Indications for surgery were also similar except for a higher incidence of nonhealing ulcer in the epidural group. There were no differences among groups for 30-day graft patency with or without reoperation, 30-day graft occlusion, death, amputation, or length of hospital stay. CONCLUSION These results suggest that the type of anesthetic given for femoral to distal artery bypass does not significantly affect 30-day occlusion rate, limb salvage rate, or hospital length of stay.

Prophylactic amrinone for weaning from cardiopulmonary bypass.

This prospective, randomised, double‐blind, controlled clinical study was performed at a single tertiary referral centre to test the hypothesis that the prophylactic administration of amrinone before separation of a patient from cardiopulmonary bypass decreases the incidence of failure to wean, and to identify those patients who could be predicted to benefit from such pre‐emptive management. Two hundred and thirty‐four patients, scheduled to undergo elective cardiac surgery, were randomly allocated to receive either a bolus dose of 1.5 mg.kg−1 amrinone over 15 min, followed by an infusion of 10 µg.kg−1.min−1, or a bolus of placebo of equal volume followed by an infusion of placebo. Treatment with amrinone or placebo was initiated upon release of the aortic cross‐clamp, before weaning from cardiopulmonary bypass. Anaesthetic technique, monitoring and myocardial preservation methods were standardised for both groups. Significantly fewer patients failed to wean in the group that received prophylactic amrinone than in the control group (7 vs. 21%, p = 0.002). Amrinone improved weaning success regardless of left ventricular ejection fraction, although this benefit was statistically significant only in the group with left ventricular ejection fractions > 55%. Of the 32 patients who failed to wean from cardiopulmonary bypass, 14 had normal pre‐operative left ventricular ejection fractions.

Written in granite: a history of the Ether Monument and its significance for anesthesiology.

ALTHOUGH Boston is well known for its place in the history of anesthesiology, many people do not know that a monument in the city exists to commemorate the first public demonstration of ether anesthesia (fig. 1). In fact, in decades past, every Bostonian knew of the monument erected in 1868 to honor the great discovery. But today, the structure is often overlooked. There are even some in the field of anesthesia who are unaware of its existence. In the historic Boston Public Garden, the Ether Monument sits with its marble and granite images and inscriptions addressing universal themes: the suffering caused by war, the desire on behalf of loved ones to relieve pain, and the triumph of medical science. It is a declaration of the advancements ether brought to society. Perhaps no other monument related to the origins of American medicine is so rich in history, controversies, and allegories. Unfortunately, both human memory and “what is written in stone have no necessary permanence unless successor generations can be successfully socialized to view [them] as less evanescent than a flag waving in ever-changing winds.” The purpose of this article is to present a historical overview of the origins and significance of the Ether Monument.§

Spinal anesthesia reduces oxygen consumption in diabetic patients prior to peripheral vascular surgery

Background and Objectives. The purpose of this study was to evaluate the effect of spinal anesthesia in &OV0312;2 in a uniform high‐risk patient population and also the relationship between dermatomal level of block and &OV0312;O2, neither of which has been investigated previously. Methods. The effect of spinal anesthesia on &OV0312;2 was studied in 17 diabetic patients undergoing lower limb peripheral vascular surgery. Measurements were made before and 15 minutes after administration of a tetracaine spinal anesthetic. Values for &OV0312;2 and oxygen delivery (&OV0312;O2) were derived from cardiac output as measured by thermodilution, hemoglobin concentration, and arterial and mixed venous blood gas analysis. The dermatomal level of the sensory block was determined by use of a hand‐held nerve stimulator. Results. Mean &OV0312;2 decreased by 27.7% (P = .001) (95% confidence limits, decrease of 22.4‐90.4%). Mean &U1E0A;O2 and arterial blood gases were unchanged, and the mean postspinal oxygen extraction ratio (&OV0312;O2/&U1E0A;O2) decreased by 20.5% (P = .002) (95% confidence limits, decrease of 9.1‐32.3%). There was a relationship between changes in &OV0312;O2 and sensory block height (P = .029). Conclusions. Spinal anesthesia in diabetic patients is associated with a reduction in &OV0312;O2, the extent of which appears to be, at least in part, a function of the level of spinal sensory block.

Other Monuments to Inhalation Anesthesia

THE history of anesthesiology is one commemorated by several monuments. The most recognized memorial is the Ether Monument, erected in the Boston Public Garden in 1868. While many anesthesiologists are familiar with this sculpture, there are other less-known memorials related to the introduction of surgical inhalation anesthesia and to the claimants to its discovery. This article discusses some of these other monuments and presents them in the context of the events that led to their erection. Through understanding both the monuments’ characteristics and their historical contexts, anesthesiologists can better appreciate both the early history of their profession and the impact that the proponents of the claimants had on the way this history is recorded. Monuments related to the discovery of inhalation anesthesia were created in honor of the four most recognized claimants to this discovery: William T. G. Morton, M.D. (1819–1868), Horace Wells (1815–1848), Charles T. Jackson, M.D. (1805–1880; Professor, Harvard Medical School, Boston, Massachusetts), and Crawford Long, M.D. (1815–1878). Each monument avouches that the distinction for the discovery of surgical inhalation anesthesia belongs to the person it represents. Although supporters of these claims constructed these monuments after the individual’s death, all four persons also made efforts to substantiate their assertions. These conflicting attempts for recognition (by both the claimants and their patrons) led to a vicious debate that became known as the Ether Controversy. The root of this conflict dates back to October 16, 1846, when, at the Massachusetts General Hospital, William T. G. Morton publicly administered an anesthetic using a compound that he called “Letheon.” In all, it took three trials with this anesthetic—in the last of which Morton had to reveal to the surgeons the active ingredient (sulfuric ether) in his preparation before they would agree to his administering of it—before the hospital affirmed it was safe to use in surgical procedures. Subsequently, Morton and Jackson jointly patented this process of administering “such vapors (particularly those of Sulfuric Ether)” to cause insensibility to pain during surgical procedures. Originally, it was understood that Jackson was the actual discoverer of the process and Morton was the dispenser of this knowledge—or as has been stated, “Jackson was the head, and W.T.G. Morton was the hand.” The first real outcries that ignited the Ether Controversy began when Henry Jacob Bigelow, M.D. (1818–1890; Professor Emeritus, Department of Surgery, Harvard Medical School), published his account of the trials that occurred at Massachusetts General Hospital. The article proclaimed that Jackson and Morton had discovered a way to render patients insensible to pain. When Wells, a Hartford dentist, as well as Morton’s former teacher and partner, read this article and saw that Morton and Jackson were taking credit for the discovery that insensibility to pain could be achieved through the inhalation of gases, he wrote a rebuttal. Wells explained that he had discovered this property 2 yr earlier. Pinckney Webster Ellsworth, a prominent Hartford surgeon, also wrote an article in support of Wells’ assertion that appeared in the Boston Medical Surgical Journal—so started the Ether Controversy. What finally led to the debate between Jackson and Morton was Morton’s cessation of stating that Jackson had been the discoverer of sulfuric ether’s anesthetic properties and his subsequently expressing that the discovery of surgical inhalation anesthesia was his own. Although not involved in the early portions of the Ether Controversy, in 1849 Crawford Long, M.D., a physician from Georgia, reported that he had first administered sulfuric ether during a surgical procedure on March 30, 1842, before Morton and Wells. Long may not have been as much involved in the Ether Controversy as the other claimants, but he must be considered a part of this historical conflict. Despite the Ether Controversy, two decades after Morton’s demonstration, The Ether Monument was erected in Boston’s Public Garden, commemorating the first public ether anesthetic at the Massachusetts General Hospital. Unlike other monuments in the Public Garden, such as the statues of George Washington and Edward Everett Hale, which commemorate these citizens for their achievements, the Ether Monument does not give specific claim to an individual. Rather, it focuses on the event, leaving Morton’s name conspicuously absent. The event that occurred on October 16, 1846, was one that brought fame and notoriety to both Boston and the Massachusetts General Hospital. Omitting Morton’s name could be an attempt to place the focus on the Massachusetts General Hospital or the larger City of Boston. On the other hand, the reason for this omission * Professor of Anesthesiology, † Research Assistant.

Controlling postoperative use of i.v. acetaminophen at an academic medical center

PURPOSE Results of an interprofessional formulary initiative to decrease postoperative prescribing of i.v. acetaminophen are reported. SUMMARY After a medical center added i.v. acetaminophen to its formulary, increased prescribing of the i.v. formulation and a 3-fold price increase resulted in monthly spending of more than

Vasoactive Amines and Inotropic Agents

40,000, prompting an organizationwide effort to curtail that cost while maintaining effective pain management. The surgery, anesthesia, and pharmacy departments applied the Institute for Healthcare Improvements Model for Improvement to implement (1) pharmacist-led enforcement of prescribing restrictions, (2) retrospective evaluation of i.v. acetaminophens impact on rates of opioid-related adverse effects, (3) restriction of prescribing of the drug to 1 postoperative dose on select patient care services, and (4) guideline-driven pain management according to an enhanced recovery after surgery (ERAS) protocol. Monitored metrics included the monthly i.v. acetaminophen prescribing rate, the proportion of i.v. acetaminophen orders requiring pharmacist intervention to enforce prescribing restrictions, and prescribing rates for select adjunctive analgesics. Within a year of project implementation, the mean monthly i.v. acetaminophen prescribing rate decreased by 83% from baseline to about 6 doses per 100 patient-days, with a decline in the monthly drug cost to about

Time series analysis of variables associated with daily mean emergency department length of stay

4,000. Documented pharmacist interventions increased 2.7-fold, and use of oral acetaminophen, ketorolac, and gabapentin in ERAS areas increased by 18% overall. CONCLUSION An interprofessional initiative at a large medical center reduced postoperative use of i.v. acetaminophen by more than 80% and yielded over

Cardiac Outcome After Peripheral Vascular Surgery

400,000 in annual cost savings.