Effects of thoracic epidural anesthesia on changes in ischemic myocardial metabolism induced by intracoronary injection of endothelin in dogs

Effects of Thoracic Epidural Anesthesia on Neuronal Cardiac Regulation and Cardiac Function

Cardiac sympathetic blockade with high-thoracic epidural anesthesia is considered beneficial in patients undergoing major surgery because it offers protection in ischemic heart disease. Major outcome studies have failed to confirm such a benefit, however. In fact, there is growing concern about potential harm associated with the use of thoracic epidural anesthesia in high-risk patients, although underlying mechanisms have not been identified. Since the latest review on this subject, a number of clinical and experimental studies have provided new information on the complex interaction between thoracic epidural anesthesia–induced sympatholysis and cardiovascular control mechanisms. Perhaps these new insights may help identify conditions in which benefits of thoracic epidural anesthesia may not outweigh potential risks. For example, cardiac sympathectomy with high-thoracic epidural anesthesia decreases right ventricular function and attenuates its capacity to cope with increased right ventricular afterload. Although the clinical significance of this pathophysiologic interaction is unknown at present, it identifies a subgroup of patients with established or pending pulmonary hypertension for whom outcome studies are needed. Other new areas of interest include the impact of thoracic epidural anesthesia–induced sympatholysis on cardiovascular control in conditions associated with increased sympathetic tone, surgical stress, and hemodynamic disruption. It was considered appropriate to collect and analyze all recent scientific information on this subject to provide a comprehensive update on the cardiovascular effects of high-thoracic epidural anesthesia and cardiac sympathectomy in healthy and diseased patients.

Advantages of Epidural Analgesia on Pulmonary Functions in Liver Transplant Donors

OBJECTIVE

Epidural analgesia (EA) has positive effects on anesthetic requirement, blood loss, postoperative analgesia, and pulmonary function tests (PFTs). The purpose of the present study was to investigate the effect of EA on postoperative PFTs in liver transplant donors (LTDs).

METHODS

In the present study, 66 LTDs were classified as total intravenous anesthesia (TIVA) and TIVA+EA groups. Patient's age, sex, body mass index, induction and maintenance dose of propofol (IDP and MDP), operation duration, forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), FEV₁/FVC ratio, visual analog scale (VAS), atelectasis scores, and lengths of intensive care unit (ICU) and hospital stays were recorded.

RESULTS

In the TIVA+EA group, IPD, MPD, delta-FEV₁ delta-FVC, VAS for all time, atelectasis score and length of hospital stay were significantly lower than in the TIVA group (P < .001 for all). Whereas VAS at the end of the operation was negatively correlated with delta-FEV₁ and delta-FVC (r² = 0.26 P < .001; r² = 0.41 P < .001; respectively), it was positively correlated with atelectasis score and length of ICU stay (r² = 0.49, P < .001; and r² = 0.41, P < .001; respectively). Atelectasis score was positively correlated with length of ICU stay (r² = 0.86, P < .001).

CONCLUSIONS

Reduced anesthetic requirement, better postoperative analgesia, reduced atelectasis score, and preserved PFTs can be provided with the use of EA in LTDs. Positive effects of EA on anesthesia requirement, pain management and pulmonary function are associated with outcomes.

Regional Anesthesia in Cardiac Surgery: A Friend or A Foe?

Escalating costs and change in the profile of patients presenting for cardiac surgery requires modification of perioperative management strategies. Regional anesthesia has played an integral part of many fast-track anesthesia protocols across North America and Europe. This review suggests that for patients undergoing coronary artery bypass graft surgery, the risk-to-benefit ratio is in favor of epidural and spinal anesthesia, provided there are no specific contraindications and the guidelines for the use of regional techniques in cardiac surgery are followed. Patients managed with regional techniques seem to benefit from superior postoperative analgesia, shorter postoperative ventilation, reduced incidence of supraventricular arrhythmia, and lower rates of perioperative myocardial infarction. The results of this analysis suggest that for each episode of neurologic complication, 20 myocardial infarctions and 76 episodes of atrial fibrillation would be prevented, thus, we would consider the regional anesthesia and analgesia to be an effective strategy that improves perioperative morbidity. However, other treatment modalities such as the addition of calcium channel blockers, aspirin, and beating heart surgery, are also suggested to be beneficial in cardiac surgical patients and may impose less risk than the use of regional techniques. We believe that the results presented in this review are encouraging enough to permit continued investigation. A prospective, randomized, controlled multicenter trial needs to be adequately powered to answer important clinical questions and allow for a long-term follow-up.

Thoracic epidural anesthesia does not affect functional recovery from myocardial stunning in sevoflurane-anesthetized dogs

OBJECTIVE

A beneficial effect of thoracic epidural anesthesia (TEA) on recovery from myocardial stunning was previously shown in awake dogs. The aim of this study was to investigate the effects of TEA on recovery from myocardial stunning in sevoflurane-anesthetized dogs.

DESIGN

Randomized animal study.

SETTING

Animal laboratory of a university hospital.

PARTICIPANTS

Chronically instrumented mongrel dogs.

INTERVENTIONS

Six dogs were chronically instrumented for measurement of hemodynamics and myocardial wall thickening fraction (WTF). The following experiments were performed on separate days in a crossover fashion: (1) 10 minutes of ischemia of the left anterior descending (LAD) coronary artery during sevoflurane anesthesia without TEA and (2) 10 minutes of ischemia during sevoflurane anesthesia with TEA.

MEASUREMENTS AND MAIN RESULTS

WTF was measured awake (baseline) and at predetermined time points until complete recovery of myocardial function occurred. Induction of anesthesia led to a decrease of WTF compared with baseline. Induction of ischemia led to a further decrease of WTF to negative values, which returned to positive values within the first minute of reperfusion. There were no differences between the two experimental conditions at any of the time points measured. In awake dogs, TEA improved the recovery from myocardial stunning compared with the control experiment. There was no difference between conscious dogs with TEA or sevoflurane-anesthetized dogs with or without TEA.

CONCLUSION

TEA has no additional protective effect on the recovery of WTF during sevoflurane anesthesia.