Peri-operative beta-blockade and haemodynamic optimisation in patients with coronary artery disease and decreasing exercise capacity presenting for major noncardiac surgery

Physiological relationship between cardiorespiratory fitness and fitness for surgery: a narrative review

Epidemiological evidence has highlighted a strong relationship between cardiorespiratory fitness and surgical outcomes; specifically, fitter patients possess heightened resilience to withstand the surgical stress response. This narrative review draws on exercise and surgical physiology research to discuss and hypothesise the potential mechanisms by which higher fitness affords perioperative benefit. A higher fitness, as indicated by higher peak rate of oxygen consumption and ability to sustain metabolic homeostasis (i.e. higher anaerobic threshold) is beneficial postoperatively when metabolic demands are increased. However, the associated adaptations with higher fitness, and the related participation in regular exercise or physical activity, might also underpin the observed perioperative benefit through a process of hormesis, a protective adaptive response to the moderate and intermittent stress of exercise. Potential mediators discussed include greater antioxidant capacity, metabolic flexibility, glycaemic control, lean body mass, and improved mood.

Landiolol has a less potent negative inotropic effect than esmolol in isolated rabbit hearts

PURPOSE

We compared the negative chronotropic and inotropic effects of landiolol and esmolol, two clinically available short-acting beta1-blockers with high beta1-selectivity, using whole isolated rabbit heart preparations.

METHODS

Tachycardia was induced by continuous perfusion of 10(-7) M isoproterenol, and we used concentrations of landiolol or esmolol in ascending steps (1 . 10(-6), 3 . 10(-6), 1 . 10(-5), 3 . 10(-5), and 1 x 10(-4) M). Heart rate (HR), left ventricular developed pressure (LVDP), the maximal rates of left ventricular force development (LVdP/dt(max)), and myocardial oxygen consumption (MVO2) were measured and compared.

RESULTS

Both landiolol and esmolol produced dosedependent decreases in HR, LVDP, LVdP/dt(max), and MVO2. The HR lowering effects of the two agents were comparable. At concentrations of 3 . 10(-5) and 1 . 10(-4) M, esmolol produced more profound depression of LVDP (47 +/- 26 and 12 +/- 11 mmHg, respectively; mean +/- SD) and reduction of LVdP/dt(max) (650 +/- 287 and 120 +/- 103 mmHg x s(-1)) than landiolol (68 +/- 20 and 64 +/- 20 mmHg, and 897 +/- 236 and 852 +/- 240 mmHg.s(-1), respectively). At the same concentrations, esmolol caused more profound reduction in MVO(2) (40 +/- 11 and 35 +/- 10 microl x min(-1) x g(-1)) than landiolol (50 +/- 8 and 48 +/- 8 microl x min(-1) x g(-1)), respectively.

CONCLUSION

Our results indicate that in the isolated rabbit heart, landiolol and esmolol had equipotent negative chronotropic effects, however, landiolol had a less potent negative inotropic effect than esmolol.

Age and sex-related differences in dose-dependent hemodynamic response to landiolol hydrochloride during general anesthesia

OBJECTIVE

Landiolol hydrochloride is a new ultra-short-acting beta(1)-adrenergic receptor blocking agent that is used for patients with tachycardia during general anesthesia. The hemodynamic response to a beta-adrenergic receptor blocking agent is generally dependent on the subject. In the present investigation we investigated the effects of age and sex on the hemodynamic response to different doses of landiolol.

METHODS

Following a persistence of tachycardia for more than 1 min, landiolol was infused at 0.03125, 0.0625 and 0.125 mg kg(-1) min(-1) for 1 min followed by 0.01, 0.02 and 0.04 mg kg(-1)min(-1) for 10 min in groups L, M and H, respectively. Heart rate (HR), systolic (sBP) and diastolic blood pressure (dBP) were recorded each minute during the procedure. The respective changes were evaluated using logistic analysis with the equation Y(t) = p + (q - p)/[1 + exp {4m/(q - p))(k - t)}], where p, q, m and k indicate the upper asymptote, lower asymptote, maximum slope and time at the maximum slope.

RESULTS

Parameters q and k for HR in group H were smaller than those in group L, whereas the parameters for sBP and dBP were unchanged among the three groups. Parameter q for HR in group H decreased with age of the patient. There was no significant difference in the landiolol-induced change in HR between males and females.

CONCLUSION

The hemodynamic response to landiolol is reliably modeled by the logistic function, especially in terms of HR. Landiolol causes a rapid and dose-dependent decrease in HR, whereas landiolol-induced changes in sBP and dBP are independent of dose. The landiolol-induced decrease in HR becomes larger with aging, but shows no sex difference. The logistic model may be useful for studying hemodynamic responses to landiolol based on age and sex differences, and may allow development of an improved monitoring system.

IMPLICATION STATEMENT

The logistic function reliably represents the hemodynamic responses to landiolol. Landiolol reduces HR rapidly and in a dose-dependent manner whereas landiolol-induced changes in sBP and dBP are independent of dose. A larger decrease in HR is caused by landiolol in elderly patients, but there is no sex difference in the landiolol-induced change in HR.

Lessons learned from a randomised controlled study of perioperative beta blockade in high risk patients undergoing emergency surgery

BACKGROUND

Perioperative beta blockade has been shown to reduce mortality after major elective surgery. The aim of this study was to determine whether it could reduce the rate of death and morbidity from cardiac complications in high risk patients undergoing emergency surgery.

METHODS

Over a one-year interval all patients undergoing major non-elective orthopaedic or general surgery were screened to identify those at high risk of cardiac complications. Consenting, high risk patients were randomly allocated atenolol or placebo for seven days, commencing at anaesthetic induction. Deaths and cardiac complications within 30 days were recorded.

RESULTS

Some 2351 patients had an emergency operation; 145 were at high risk and eligible for the study. Of 89 patients approached, 57 initially consented. Only 38 patients, however, completed the study protocol, 19 were withdrawn. Of those who completed the study, 5/20 patients in the placebo group and 3/18 in the treatment group died before hospital discharge (p=0.520). Four others in the placebo group and two in the atenolol group had post-operative non-fatal cardiac events (positive troponin T), p=0.311.

CONCLUSIONS

This study of emergency surgery proved more difficult than similar trials in elective surgery. The final study groups were small and there were no significant differences in outcomes. A much larger study is required for a definitive answer.

Excellent anaesthesia needs patient preparation and postoperative support to influence outcome

PURPOSE OF REVIEW

Studies over many years have demonstrated that preoptimization and attention to appropriate perioperative care is associated with a substantial decrease in surgical mortality. This review discusses ways in which patient preparation and perioperative support can minimize surgical mortality and morbidity.

RECENT FINDINGS

Scoring systems continue to be developed in order to classify categories of surgical risk. Objective physiologically based assessments can also identify high-risk groups of patients. Debate continues over the indications for specific interventions such as beta-blockade or statin therapy. There is continuing interest in perioperative optimization of oxygen delivery. A multimodality approach paying attention to a range of possible interventions appears to be beneficial. Audit, training, experience and a sufficient volume of procedures are all factors associated with surgical mortality.

SUMMARY

The provision of a high-quality service throughout the perioperative period is vital for a successful outcome. Patients need to be assessed well before major elective surgery to determine if they fall into a high-risk category. Some patients may benefit from a change in management. Postoperatively, critical-care support should be available backed by level 1 (enhanced ward) care with input from outreach or medical emergency teams 24 hours per day, seven days a week.

Recent developments in beta-blockers and anaesthesia

PURPOSE OF REVIEW

To evaluate developments on the subject of beta-blockers and anaesthesia published in the past 12 months. The administration of beta-blockers has been established as a pharmacological approach to reduce cardiac events in the perioperative period. A number of studies and reviews have been published underlining the appropriateness of this approach in patients undergoing non-cardiac as well as cardiac surgery. A lack of transfer of the scientific knowledge to clinical practice is evident not only in the field of perioperative medicine, which results in an under-use of beta-blockers. Open questions are still directed towards the optimal dosage, the effectiveness of chronic beta-blockade and the effects of beta-blockade in traumatized and burned patients.

RECENT FINDINGS

Progress in the use of beta-blockers has been realized by the introduction of institutional protocols. In chronic beta-blockade a simple continuation does not provide effective protection. Improved protection might be gained by the combination of beta-blockers and statins in high-risk patients. The role of beta-blockers in pain management is currently a field of interest, although there seem to be many open questions. There are still doubts about the evidence of perioperative beta-blockade: the results of large trials will be published in the next 2 years. The approach is cost-effective: a comparison with other alternative approaches to cardioprotection is pending.

SUMMARY

There has been significant progress in the use of perioperative beta-blockade. Although a considerable amount of knowledge is obvious, the optimal strategy in different clinical settings is still a matter of debate.

Landiolol attenuates tachycardia in response to endotracheal intubation without affecting blood pressure

PURPOSE

Beta-adrenergic receptor antagonists (beta-antagonists) have long been used to control perioperative tachyarrhythmias. The effects of a beta(1)-antagonist, landiolol, on perioperative hemodynamics are unknown. We aimed to determine the appropriate dosage of landiolol for the treatment of hemodynamic changes in response to endotracheal intubation.

METHODS

Sixty-four patients without heart disease or hypertension, were assigned to receive saline (group C) or landiolol (0.1 or 0.3 mg.kg(-1); groups L1 and L3). Anesthesia was induced with propofol (2 mg.kg(-1) iv) followed by saline or landiolol iv. After ventilation with facemask using 2% sevoflurane in 100% oxygen for 90 sec, endotracheal intubation was performed. After intubation, anesthesia was maintained using 1% sevoflurane in combination with 50% nitrous oxide. Values of heart rate and mean arterial blood pressure were recorded before induction to five minutes after intubation.

RESULTS

In group C, heart rate and mean blood pressure increased simultaneously after tracheal intubation, compared with baseline values. Heart rate values were attenuated immediately before as well as after intubation in group L3, compared with groups C and L1. Heart rate did not increase after tracheal intubation in group L1, compared with baseline. In contrast, mean arterial blood pressure values did not differ among groups.

CONCLUSIONS

The newly developed beta(1)-antagonist landiolol (0.1 and 0.3 mg.kg(-1)) may help prevent tachycardia without affecting blood pressure during the induction of anesthesia.

Relationship between the inability to climb two flights of stairs and outcome after major non-cardiac surgery: implications for the pre-operative assessment of functional capacity

Functional capacity is an integral component of the pre-operative evaluation of the cardiac patient for non-cardiac surgery. Stair climbing capacity has peri-operative prognostic importance. It may predict survival after lung resection and complications after major non-cardiac surgery. However, stair climbing cannot determine the aerobic metabolic capacity necessary to survive the peri-operative stress response. The potential benefits and current limitations of cardiopulmonary exercise testing to determine peri-operative aerobic capacity are discussed. Principles for the selection of an appropriate screening test of aerobic function are put forward.