Intercurrent drug therapy and perioperative cardiovascular mortality in elective and urgent/emergency surgical patientst

Risk of intraoperative hypotension with loop diuretics: a randomized controlled trial

BACKGROUND

There is growing concern regarding the safety of blood pressure-lowering medications administered during the perioperative period. Whether loop diuretics also induce intraoperative hypotension is uncertain. Our objective was to compare the effects of continuing or withholding furosemide on the day of noncardiac elective surgery on intraoperative hypotension among chronic users of furosemide.

METHODS

A double blind, randomized, placebo controlled trial was conducted at 3 North American university centers between September 2000 and December 2006. Participants were randomly assigned in a 1:1 ratio to receive either furosemide or placebo on the day of surgery. The primary outcome was risk of developing intraoperative hypotension. A priori secondary outcomes included risk of heart failure; composite cardiovascular event (myocardial infarction, arrhythmia, stroke or transient ischemic attack, or death); and change in renal function and electrolytes.

RESULTS

Of the 212 patients enrolled, 193 patients underwent surgery. There was no significant difference in risk of developing intraoperative hypotension between the furosemide (49%) and placebo (51.9%) groups (relative risk [RR], 0.95; 95% confidence interval [CI], 0.72-1.24; P = .78). The intraoperative administration of vasopressors and fluids were similar between both groups. The risk of developing postoperative cardiovascular events was not significantly different between those randomized to furosemide (4.8%) or placebo (2.8%) (RR, 1.73; 95% CI, 0.42-7.06; P = .49). There was no significant difference in renal function or electrolytes between the 2 groups.

CONCLUSION

Among elective, noncardiac surgeries in patients chronically treated with furosemide, the administration of furosemide on the day of surgery did not significantly increase the risk for intraoperative hypotension.

Dihydropiridine calcium-channel blockers and perioperative mortality in aortic aneurysm surgery

BACKGROUND

Dihydropiridine calcium-channel blockers are often used as an alternative to beta-blockers for the treatment of hypertension in patients undergoing aortic aneurysm surgery. We studied the relation between dihydropiridine calcium-channel blocker use and perioperative mortality in patients undergoing aortic aneurysm surgery.

METHODS

We studied 1000 patients [mean (range) age, 69 (22-95) yr; males 810] who underwent acute or elective abdominal or thoracoabdominal aortic aneurysm surgery between January 1999 and April 2007, at Semmelweis Medical University (Budapest, Hungary). Patients were evaluated for clinical risk factors, chronic medication use, and surgical characteristics. Propensity score analysis was used to adjust for the potential bias in dihydropiridine calcium-channel blocker use. Multivariable logistic regression analyses were applied to study the association between the likelihood of dihydropiridine calcium-channel blocker use and mortality occurring within 30 days of surgery.

RESULTS

Perioperative mortality occurred in 85 (8.5%) patients. Thirty-day mortality was significantly higher in dihydropiridine calcium-channel blocker users compared with non-users, 14.0% vs 6.0%; crude odds ratio (OR) 2.6, 95% confidence interval (CI): 1.6-4.0, P<0.0001. Even after correcting for other baseline covariates and propensity for these agents dihydropiridine calcium-channel blocker use was associated with increased 30-day mortality, OR (95% CI) 2.5(1.3-4.6), P=0.003.

CONCLUSIONS

Dihydropiridine calcium-channel blocker use in patients with acute or elective aortic aneurysm surgery is independently associated with an increased incidence of perioperative mortality.

[Perioperative heart rate in patients taking beta-blockers: reality and efficiency of the treatment]

OBJECTIVE

To compare perioperative heart rate (HR) control of patients chronically exposed to beta-blockers (BB) with those of patients whom BB treatment was initiated one week preoperatively.

METHODS

HR was noticed at three successive time periods: the anaesthesia visit, just before induction of anaesthesia, and during surgery (maximum and minimum HR). HR, presented as mean+/-SD, was compared among 3 groups of patients: BB chronic treatment, preoperative BB, and a control group not taking BB.

RESULTS

Four hundred (and) six patients were included: 181 chronic BB patients, 20 preoperative BB, and 205 control patients. As compared to the control group, HR of chronic BB patients were lower (P<0.05) than those of the control group at the three time period of the study. In the preoperative BB patient group, one week BB treatment resulted in a mean 30% reduction of HR. Just before induction of anaesthesia, HR of preoperative BB patients was lower than that of chronic BB patients (55+/-11 vs 67+/-13 b/min; P<0.05).

CONCLUSION

Beta-blockers treatment initiated one week before surgery could be more effective on perioperative HR control than chronic BB treatment.

Implication of aging on anesthetic drugs

PURPOSE OF REVIEW

The elderly population is increasing in number each year, and more patients are presenting for anesthesia and surgery. One of the key areas for improving the care of the elderly is a better understanding of the influence of aging on drug pharmacokinetics and dynamics.

RECENT FINDINGS

We now know more about the effects of risk factors on the occurrence of postoperative complications, and strategies to improve outcome after anesthesia and surgery. Two such strategies include the role of perioperative beta-adrenoceptor blockade in obtunding cardiovascular responses and myocardial ischaemia, and the provision of effective perioperative analgesia. Both topics have featured in key publications during the past year. Cognitive dysfunction following surgery occurs in about 10% of elderly patients; possible etiologies include a decline in central nervous system cholinergic function. One major disease of the elderly is Parkinson's disease, which offers challenges to the anesthesiologist both with regard to alterations of physiology and in choice of anesthetic drugs and techniques.

SUMMARY

The effects of comorbidity and intercurrent medications may alter the normal anesthetic practice of the clinician's care of the elderly patient. Further studies in these key areas may lead to improved outcomes.

Ischemic heart disease

Because of changing demographics, increasing numbers of patients with IHD are presenting for noncardiac surgery, and the risks of perioperative morbidity and mortality are significant. The Lee Cardiac Risk Index is applicable in defining perioperative cardiac risk: however, ACC/AHA guidelines may not be applicable comprehensively. The role of biomarkers in risk stratification still needs to be defined. Structured management protocols that help assess, diagnose, and treat patients with IHD preoperatively are likely to help decrease postoperative morbidity and mortality, but clearly are not applicable to all patients. Augmented hemodynamic control with beta-blockers or alpha-2 agonists and modulating inflammation by statins can play an important role in improving outcomes in many patients with IHD; preoperative coronary revascularization may be of limited value. Intraoperative anesthetic management that minimizes hemodynamic perturbations is important; however, the choice of a particular technique typically is not critical. Of critical importance is the postoperative management of the patient. Postoperative myocardial injury should be identified, evaluated, and managed aggressively. Secondary stresses such as sepsis, extubation, and anemia, which can increase demand on the heart, should be treated or minimized. Clearly, optimal care of the patient with IHD entails closely coordinated assessment and management throughout the preoperative, intraoperative, and postoperative phases, if one is to optimize short- and long-term outcomes.

Interférence des médicaments cardiovasculaires avec l'anesthésie et la chirurgie

Decisions about chronic treatments during the perioperative period must be made at the presurgical anesthesia consultation. It is increasingly rare to stop treatment during this period, because: This new rule is applied particularly to patients with cardiovascular disorders. Beta blockers have a special role in preventing the onset of postoperative cardiovascular events. The role of statins requires further precision but they appear to fit into the same preventive approach. Interruption of antiplatelet agents appears to be associated with a risk of arterial thrombosis in patients with coronary conditions, notably those with conventional stents and most especially those with drug-eluting stents.

Perioperative management of chronic heart failure

Heart failure (HF) is one of the few cardiac conditions that is increasing. Despite a better understanding of how hormones and other signaling systems underlie the pathophysiology, and despite improved outcomes from pharmacologic therapy, many HF patients receive no effective treatment. Patients with HF commonly require medical diagnosis and management in operating rooms and critical care units; thus anesthesiologists are obliged to remain up-to-date both with advances in outpatient (chronic) medical management and with inpatient treatments for acute exacerbations of HF. Accordingly, we reviewed angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-adrenergic receptor blockers, and aldosterone antagonists because these drugs prolong life and are included in current clinical practice guidelines for treating patients with chronic HF. We also reviewed the implications of chronic HF for patients undergoing surgery and anesthesia and discuss how best to provide intensive treatment for acute exacerbations of symptoms, such as might be caused by excessive intravascular volume, inappropriate drug "holidays," or worsening of the underlying cardiac disease.

Preoperative β-blocker use: is titration to a heart rate of 60 beats per minute a consistently attainable goal?

STUDY OBJECTIVE

To quantify the prevalence of perioperative beta-blocker use and its impact on preoperative and preinduction heart rate (HR), in light of the recent publication of specific recommendations regarding perioperative beta-blocker use and desired HR.

DESIGN

Retrospective observational study in patients who underwent elective and coronary artery bypass graft (CABG) surgery between January 2001 and March 2002.

SETTING

Tertiary-care teaching hospital.

MEASUREMENTS

Percentage of eligible patients who received beta-blockers preoperatively and the impact of non-protocol-based beta-blocker therapy on preadmission and preinduction HR were recorded. Differences were assessed with unpaired t test and chi(2) analysis; P < .05 was considered significant, with corrections for multiple comparisons.

RESULTS

Of the patients who underwent vascular surgery, 9 had documented prior beta-blocker intolerance. Of the remaining 172 patients, 94.8% had indication for perioperative beta-blocker use. However, only 47.7% of the eligible patients received beta-blockers. Of the 155 CABG patients, 74.2% were taking beta-blockers preoperatively. Only 29% of vascular patients and 32% of CABG patients who were receiving beta-blockers had HR less than 60 beats per minute (bpm) at preadmission. The mean preadmission HR in vascular surgery patients was 65.2 +/- 11 and 73.2 +/- 13.8 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .0001). In CABG surgery patients, preadmission HR values were 64.2 +/- 13 and 76.1 +/- 12 bpm in beta-blocker and non-beta-blocker patients, respectively (P = .001). The preinduction HR subsequently increased in the beta-blocker as well as in the non-beta-blocker groups.

CONCLUSION

Only half of the patients who qualify to receive preoperative beta-blockers by current recommendations actually receive them before noncardiac surgery, and the majority of these patients have preadmission and preinduction HR less than 60 bpm. Targeting beta-blocker therapy treatment to an HR less than 60 bpm may not be readily achievable in many patients.

Administration périopératoire de bêtabloquants : enquête de pratique

OBJECTIVES

To evaluate the anaesthesiologists' attitude concerning the perioperative administration of betablockers (BB), especially prophylactic BB, in order to prevent postoperative cardiac complications.

METHODS

A questionnaire including 20 items was sent to 700 anaesthesiologists of 4 French departments (Ain, Isere, Loire et Rhone).

RESULTS

The response rate was 30%. Eighty-eight percent of respondents prescribed the BB with the premedication, on the day of the surgery in patients who were on regular BB. Before major surgery, 37% percent of respondents always or usually introduced prophylactic BB in patients with high cardiac risk. Atenolol was the drug of choice for 68% of perioperative BB users. Seventy-one percent of anaesthesiologists using prophylactic BB asked for a cardiologic opinion before starting BB therapy.

CONCLUSION

In practice, anaesthesiologists continued BB during the perioperative period in patients who were on chronic treatment with BB. However, prophylactic perioperative administration of BB in patients with high cardiac risk is still inadequate and dependent on a cardiologic opinion.

Effect of chronic β-blockade on peri-operative outcome in patients undergoing non-cardiac surgery: an analysis of observational and case control studies*

Little is known about the effect of chronic beta-adrenoceptor antagonist therapy during the peri-operative period in patients undergoing non-cardiac surgery. We conducted a literature review to identify studies examining the relationship between chronic therapy and adverse peri-operative outcome. Eighteen studies were identified in which it was possible to ascertain the incidence of adverse cardiac outcomes in those patients who were and were not receiving chronic beta-blocker therapy. None of the studies demonstrated a protective effect of chronic beta-blockade. The results of these studies were then combined and a cumulative odds ratio calculated for the likelihood of myocardial infarction, cardiac death and major cardiac complications. Patients receiving chronic beta-blocker therapy were more likely to suffer a myocardial infarction (p < 0.05). These findings differ from the published effects of acute beta-blockade. Reasons for this discrepancy are considered.

Assessment and management of patients with ischemic heart disease

OBJECTIVE

Review the perioperative management of patients who are scheduled for noncardiac surgery.

DATA SOURCE

Review of literature (PubMed, MEDLINE).

CONCLUSIONS

Patients with ischemic heart disease who undergo noncardiac surgery are at significant risk of perioperative cardiac morbidity and mortality. Recent joint guidelines from the American College of Cardiology and American Heart Association have significantly streamlined the preoperative evaluation processes. Augmented hemodynamic control with intensive perioperative pharmacologic therapy with beta-blockers and possibly alpha-2 agonist has been shown to improve perioperative cardiovascular outcomes. However, translating this information to clinical practice continues to be a challenge and requires a multi- disciplinary approach. A particular intraoperative anesthetic technique is unlikely to influence perioperative cardiac morbidity and mortality. Postoperative management with goals of decreasing hemodynamic stress is important in patients with ischemic heart disease. Diagnosis and management of perioperative myocardial infarction continues to be a challenge. However, use of cardiac specific biomarkers should improve the diagnostic process.

Perioperative beta-blockade: a survey of physician attitudes in the department of veterans Affairs

OBJECTIVE

To delineate clinician opinion on the efficacy, safety, and logistics of perioperative beta-adrenergic blockade for patients undergoing noncardiac surgery.

DESIGN

Survey of opinions and clinical practices.

SETTING

Internet-based survey form.

PARTICIPANTS

Members of the Associations of Veterans Affairs Anesthesiologists and Surgeons and chiefs of cardiology in centers with surgical programs.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred twenty-seven responses from 62 Veterans Affairs Medical Centers in 35 states (57 anesthesiologists, 45 surgeons, 25 cardiologists) were analyzed. Ninety-two percent agreed that it is effective in reducing short-term adverse outcomes, declining to 60% for long-term outcome. There was greater enthusiasm for its use in patients with known coronary artery disease (87%) than in patients with risk factors only (72%). Although 66% considered it efficacious in vascular surgery, only 30% were convinced it was for nonvascular surgery (with a similar distribution for safety in these settings). Preoperative use was favored (94%), with most physicians favoring use within 1 week of surgery (52%). Most favored 1 to 2 weeks of postoperative therapy (43%), with the remainder favoring shorter (19%) or longer (35%) durations. Although 71% of clinicians reported frequent use in their practice, most believed its use was largely informal by their colleagues (83%) and rarely based on a formal clinical pathway (13%).

CONCLUSION

A wide range of opinions by clinicians regarding the efficacy, safety, and logistics of perioperative beta-adrenergic blockade was encountered, suggesting need for additional clinical research and centralized efforts at increasing compliance with existing guidelines.

Calcium channel blockers for reducing cardiac morbidity after noncardiac surgery: a meta-analysis

Cardiac complications are the leading cause of death after noncardiac surgery. Despite theoretical benefits, calcium channel blockers (CCB) are not widely used in the perioperative setting. This systematic review assessed the efficacy of CCBs during noncardiac surgery. MEDLINE, EMBASE, Science Citation Index, PubMed, and reference lists were searched without language restriction for randomized controlled trials (RCT) evaluating CCBs during noncardiac surgery. Two reviewers independently abstracted data on death, myocardial infarction (MI), ischemia, supraventricular tachyarrhythmia (SVT), and congestive heart failure (CHF). Treatment effects were calculated as relative risks (RR) with 95% confidence intervals (CI). Eleven studies (1007 patients) were included. CCBs significantly reduced ischemia (RR, 0.49; 95% CI, 0.30-0.80; P = 0.004) and SVT (RR, 0.52; 95% CI, 0.37-0.72; P < 0.0001). CCBs were associated with trends towards reduced death and MI. In post hoc analyses, CCBs significantly reduced death/MI (RR, 0.35; 95% CI, 0.15-0.86; P = 0.02) and major morbid events (MME), defined as death, MI, or CHF (RR, 0.39; 95% CI, 0.17-0.89; P = 0.02). In subgroup analyses, diltiazem significantly reduced ischemia, SVT, death/MI, and MMEs. This meta-analysis shows CCBs significantly reduced ischemia, SVT, and combined end-points in the setting of noncardiac surgery. The majority of these benefits are attributable to diltiazem, suggesting the need for further evaluation of this drug in a large RCT.

Interrupting drug therapy in the perioperative period

Millions of patients undergo surgery each year and an increasing proportion of these patients are consuming therapeutic drugs. Drug therapy is often withheld in the immediate perioperative period and after major surgery, in particular, there is often a prolonged period of fasting. This may lead to withdrawal effects including recurrence or worsening of patients' disease symptomatology. These effects will occur during a period of physiological and pathophysiological stresses and render patients more vulnerable to drug withdrawal phenomena. Thus, patients may be exposed to greater and sometimes unnecessary risks in the perioperative period. There are relatively few studies that have investigated this problem. The ones that have, however, confirm that drug abstinence in the perioperative period is a relatively common phenomenon and one study has demonstrated an association between duration of drug abstinence and adverse outcomes. The pathophysiological effects of major surgery on gastrointestinal function, neuro-humoral and cytokine adaptive responses to surgical stress are under-appreciated. These responses can reduce the effectiveness of oral administration and exacerbate co-existing disease processes. These problems are compounded by a fragmented approach to perioperative drug therapy with no one group of healthcare professionals assuming responsibility for this aspect of care. This may in part be a consequence of the complexities of rationalising drug therapy in the perioperative period together with the lack of readily available and evidence based information strategies for individual drugs or drug classes. An additional problem relates to the formulations, inherent pharmacokinetics and limited routes of administration of many prescribed drugs. These can prevent a 'seamless' transition from preoperative to postoperative management. Consumers, health professionals, pharmaceutical companies and drug regulatory agencies must all play a part in rectifying this problem. There remains a need for further research to clarify the effects of abstinence on patient outcomes and also to identify optimum strategies to avoid unwanted drug abstinence.

Issues in the perioperative management of the elderly patient with cardiovascular disease

The elderly patient may show normal physiological changes of the cardiovascular and respiratory systems that accompany aging, as well as features of intrinsic cardiac disease. The latter include: a past history of myocardial infarction or ischaemic heart disease; history of congestive cardiac failure; angina; arterial hypertension (BP >140/90mm Hg); and conduction disorders. A key aspect to the safe and effective anaesthetic management of the elderly patient with cardiac disease is a careful preoperative assessment and optimisation of pre-existing drug therapies. All cardiac medications should be continued up to and including the morning of surgery with the exception of anticoagulation involving warfarin, and perhaps large doses of angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists in patients with hypertension or heart failure. Anaesthetic techniques used in these patients should avoid episodes of excessive hypotension after induction of anaesthesia or large blood loss, or the combination of hypertension and tachycardia after noxious stimulation. The latter physiological disturbances are pivotal for the development of myocardial ischaemia. Both premedication (if used) and anaesthesia should avoid excessive sedation and respiratory depression. The choice of anaesthetic technique may vary between: a balanced technique involving an opiate and a volatile agent; an intravenous technique utilising infusions of propofol; or regional anaesthesia with or without additional sedation. There are no good data to suggest any one technique is better than the rest. The occurrence of ischaemia in the perioperative period may precede the postoperative development of significant cardiac morbidity and mortality (including myocardial infarction or unstable angina, congestive cardiac failure, cerebrovascular accidents, and severe arrhythmias). A number of strategies have been examined to reduce these adverse outcomes. The effect of acute beta-adrenoceptor blockade in treatment-naive patients is associated with reduction in the haemodynamic response to noxious stimuli and decreased ECG evidence of myocardial ischaemia, as well as a reduction in the number of cardiac adverse events. Other drugs (calcium channel antagonists, alpha(2)-agonists and adenosine modulators) have a less predictable influence on both myocardial ischaemia and hard cardiac outcomes. There is inadequate evidence at present to define the optimal time course for acute beta-blockade, or the groups of patients in whom preoperative beta-blockade should be initiated in the absence of contraindications. Nevertheless, addition of beta-blockers to the preoperative regimen should be considered in patients with evidence of or at risk for coronary disease undergoing major surgery. There is also evidence that long-term beta-adrenoceptor or calcium channel blockade or nitrate therapy for the high-risk cardiac patient offers little protection against silent myocardial ischaemia, nonfatal infarction, cardiac failure and cardiac death.

Significance of beta-blockers in the perioperative period

Beta-blockers have emerged as one of the key therapeutic agents that can decrease cardiac morbidity and mortality. Advances in cardiac beta-adrenergic receptor physiology and pharmacology have provided new insights into the beneficial effects of beta-blockers in cardiovascular medicine. Although significant advances have been made, many specific questions still remain to be answered. We will review some of these developments and the current role of beta-blockers in peri-operative medicine.