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.This review provides a comprehensive update on the cardiovascular effects of high-thoracic epidural anesthesia and cardiac sympathectomy in healthy and diseased patients.

Cardiovascular parameters and liver blood flow after infusion of a colloid solution and epidural administration of ropivacaine 0.75%: the influence of age and level of analgesia.

BACKGROUND AND OBJECTIVE: Lumbar epidural anaesthesia induces cardiovascular changes and decreases liver blood flow (Qh). We studied the effects of age on haemodynamics, blood volumes and Qh before and after epidural anaesthesia. METHODS: Thirty-six patients were enrolled as follows: group 1, 20-44 years; group 2, 45-70 years; group 3, >70 years. Using pulse dye densitometry, in addition to heart rate and arterial blood pressure (arterial BP), cardiac output, total blood volume, central blood volume and Qh were measured, before and after colloid infusion (500 ml hydroxyethyl starch, 6%) and after epidural administration of 15 ml of 0.75% ropivacaine. RESULTS: With age the level of analgesia [median (range)] increased from T7 (L2-T4) in group 1 to T4 (T10-C7) in group 3 (P = 0.04). After colloid infusion, heart rate (mean difference +/- SE; 2.1 +/- 0.7 beats min(-1)), systolic BP (4.1 +/- 2.2 mmHg) and Qh 162 ml min(-1) (ratio 0.90, 95% confidence interval 0.81-0.99) increased slightly but significantly, and were unaffected by age. Epidural anaesthesia induced a significant decrease in Qh (265 ml min(-1); ratio 1.20, 95% confidence interval 1.07-1.35) and arterial pressure (for systolic BP: P = 1 x 10(-7)). A significantly larger decrease in systolic BP occurred in the older, compared with the middle, age group (P = 0.04). Age did not affect epidural-induced changes in cardiac output, total and central blood volumes, and Qh. CONCLUSION: Age increases the level of analgesia after epidural ropivacaine and is associated with a more pronounced decrease in arterial pressure. A colloid preload mildly increases haemodynamics, but this insufficiently prevents younger and elderly patients from a decrease in Qh after lumbar epidural anaesthesia.

Are epidurals worthwhile in vascular surgery?

PURPOSE OF REVIEW: Patients undergoing major vascular surgery are at increased risk for postoperative complications due to the high incidence of comorbidities in this population.Epidural anaesthesia provides potential benefits but its effect on morbidity and mortality is unclear. RECENT FINDINGS: Existing studies fail to demonstrate improved clinical outcome and reduced mortality for epidural anaesthesia or combined epidural/general techniques compared with general anaesthesia. Postoperative epidural analgesia provides better pain relief and reduces the duration of postoperative mechanical ventilation. SUMMARY: Optimization of perioperative care rather than the anaesthetic technique may have potential benefit in improving postoperative outcome.

The effect of age on the systemic absorption and systemic disposition of ropivacaine after epidural administration.

Knowledge about the systemic absorption and disposition of ropivacaine after epidural administration is important in regard to its clinical profile and the risk of systemic toxicity. We investigated the influence of age on the pharmacokinetics of ropivacaine 1.0% after epidural administration, using a stable-isotope method. Twenty-four patients were enrolled in 1 of 3 groups according to age (group 1: 18-40 yr; group 2: 41-60 yr; group 3: > or =61 yr). Patients received 150 mg ropivacaine hydrochloride epidurally. After 25 min, patients received 50 mL 0.44 mg/mL deuterium-labeled ropivacaine (D3-ropivacaine) IV. Arterial blood samples were collected up to 24 h after epidural administration. Total plasma concentrations of ropivacaine and D3-ropivacaine were determined using liquid chromatography mass spectrometry. In the oldest patients, elimination half-life was significantly longer (ratio of the geometric means 0.60; 95% confidence interval, 0.37-0.99) and clearance was significantly decreased (mean difference, 194 mL/min; 95% confidence interval, 18-370 mL/min) compared with the youngest patients. The systemic absorption was biphasic. Absorption kinetics for ropivacaine (fractions absorbed: (F1, F2) and half-lives: (t(1/2),a1), t(1/2),a2) during the fast and slow absorption process: 0.27 +/- 0.08 and 0.77 +/- 0.12, respectively; 10.7 +/- 5.2 min and 248 +/- 64 min, respectively) were in the same range as for other long-acting local anesthetics. F1 was on average 0.11 (95% confidence interval, 0.002-0.22) higher in the youngest compared with the middle age group. Observed age-dependent pharmacokinetic differences do not likely influence the risk of systemic toxicity in the elderly after a single epidural dose of ropivacaine.

Complications and local anaesthetic toxicity in regional anaesthesia.

PURPOSE OF REVIEW: Local anaesthetic agents are administered every day in clinical practice. These agents are relatively safe when administered in proper dosages at appropiate anatomical sites. However, when excessive dosages are administered or the incorrect site of administration is used there is a potential for toxic reactions. Ropivacaine, a pure S-enantiomer, and levobupivacaine, a single isomer of bupivacaine, have been introduced as new long-acting local anaesthetic agents with a potentially reduced toxicity compared with bupivacaine. The present review deals with recent knowledge about systemically induced local anaesthetic toxicity and localized toxicity. RECENT FINDINGS: Studies have compared cardiotoxicity directly between ropivacaine and levobupivacaine in intracoronary injection in sheep and pigs, in small mammals, and arrhythmias and resuscitation in dogs. Direct left coronary arterial infusions of local anaesthetics in a conscious sheep model precludes central nervous system actions. Intracoronary studies showed similar toxicity for levobupivacaine and ropivacaine. When comparing and interpreting in-vivo animal studies of local anaesthetic toxicity, species variations, differences in the mode and site of local anaesthetic administration, and whether the animal is under the influence of anaesthesia must all be considered. Stereoselectivity may play a role in the lengthening of the atrioventricular conduction time for bupivacaine. In-vitro studies have revealed that intracellular calcium concentrations may contribute to myotoxicity. SUMMARY: Current evidence suggests that ropivacaine is slightly less toxic than levobupivacaine; however, the difference in potency between the two agents is greater. The new local anaesthetic agents can be regarded as 'safer', but must not be regarded as safe.

The effects of age on neural blockade and hemodynamic changes after epidural anesthesia with ropivacaine.

UNLABELLED: We studied the influence of age on the neural blockade and hemodynamic changes after the epidural administration of ropivacaine 1.0% in patients undergoing orthopedic, urological, gynecological, or lower abdominal surgery. Fifty-four patients were enrolled in one of three age groups (Group 1: 18-40 yr; Group 2: 41-60 yr; Group 3: > or=61 yr). After a test dose of 3 mL of prilocaine 1.0% with epinephrine 5 microg/mL, 15 mL of ropivacaine 1.0% was administered epidurally. The level of analgesia and degree of motor blockade were assessed, and hemodynamic variables were recorded at standardized intervals. The upper level of analgesia differed among all groups (medians: Group 1: T8; Group 2: T6; Group 3: T4). Motor blockade was more intense in the oldest compared with the youngest age group. The incidence of bradycardia and hypotension and the maximal decrease in mean arterial blood pressure during the first hour after the epidural injection (median of Group 1: 11 mm Hg; Group 2: 16 mm Hg; Group 3: 29 mm Hg) were more frequent in the oldest age group. We conclude that age influences the clinical profile of ropivacaine 1.0%. The hemodynamic effects in older patients may be caused by the high thoracic spread of analgesia, although a diminished hemodynamic homeostasis may contribute. IMPLICATIONS: Analgesia levels after the epidural administration of 15 mL of ropivacaine 1.0% increase with increasing age. This is associated with an increased incidence of hypotension in the elderly, although an effect of age on the hemodynamic homeostasis may have contributed. It appears that epidural doses should be adjusted for elderly patients.