Case studies in perioperative management: Challenges, controversies, and common ground

CASE 2: RADICAL CYSTECTOMY IN ELDERLY MAN WITH CARDIAC RISK FACTORS

A 78-year-old obese Russian-speaking man is seen in the preoperative clinic prior to a scheduled radical cystectomy for highly invasive bladder cancer. He is a poor historian and argues with the several family members accompanying him, but it is determined that his medical history includes hypertension, diabetes mellitus, a myocardial infarction (MI) 5 years previously (in Russia), and stable angina that is determined to be class II.

He had no previous work-up and no electrocardiogram (ECG). His medications are aspirin, metoprolol, and metformin. His blood pressure is 190/100 mm Hg, heart rate 90 beats per minute, and body mass index 32. On examination, there is no murmur, S3 gallop, or rales. His blood glucose is 220 mg/dL, and his creatinine is slightly elevated (1.4 mg/dL). ECG verifies a prior MI.

Question 2.1: Which of the following additional tests should be ordered preoperatively?

A. Hemoglobin (Hb) A_1c

B. Lipid profile

C. Both

D. Neither

Dr. Sweitzer: Because the surgery is not elective, no immediate benefit would be achieved by ordering either an HbA_1c or a lipid profile. However, if you view the preoperative evaluation as an opportunity to manage risk factors over the long term, then it may be a good idea to order the lipid profile because this patient has rarely engaged the health care system. Likewise, the HbA_1c can be ordered to set in place his long-term management. Sometimes we focus on the preoperative visit only in the context of the surgery, but if a test or intervention is appropriate and needed for long-term management, then it is appropriate to do now.

Dr. Cohn: There is no evidence to support using the preoperative HbA_1c to alter management decisions. I would not postpone surgery based on the HbA_1c value, as I would if his glucose level were 600 mg/dL. Most of the studies that have assessed postoperative complications based on preoperative HbA_1c did not control for postoperative glucose levels. The incidence of complications varies based on the type of complication and the type of surgery.

Similarly, I would not use lipid values to guide management of this patient. Studies suggest that perioperative statin therapy may reduce postoperative morbidity and mortality in patients undergoing vascular surgery (see article by Poldermans on page S79 of this supplement), but our patient already has indications for a statin—a remote MI and diabetes—independent of what his lipid values are.

Question 2.2: How would you manage his elevated blood pressure (190/100 mm Hg)?

A. Discontinue metoprolol and start a different antihypertensive drug

B. Increase the metoprolol dose

C. Continue metoprolol and add a second drug

D. Observe him on his current regimen

Dr. Cohn: I would increase the dose of metoprolol and consider adding another drug, in view of his heart rate (90 beats per minute) and his cardiac status. Beta-blocker therapy should not be discontinued because doing so in the perioperative period is associated with an increased risk of adverse events such as cardiac death and MI.

Dr. Sweitzer: I would push up the metoprolol a bit to reduce the heart rate, knowing that beta-blockers are probably not the most efficacious antihypertensive agents. I would caution against starting an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB) because he is scheduled to undergo a fairly significant procedure with expected blood loss and fluid shifts, and either of those agents in combination with a beta-blocker would be challenging to manage on the day of surgery.

Question 2.3: How would you manage his metformin perioperatively?

A. Discontinue it 48 hours preoperatively

B. Discontinue it 24 hours preoperatively

C. Withhold it on the morning of surgery

D. Continue it on the morning of surgery

Dr. Sweitzer: We routinely advise patients to hold all their oral diabetes medications the morning of surgery, primarily because many anesthesiologists are uncertain about the differing risks of hypoglycemia associated with the various oral agents.

Most of us will never see a patient who has lactic acidosis from metformin use. A systematic literature review and analysis found no increase in the risk of lactic acidosis with metformin compared with other oral hypoglycemics,⁶ so fear of lactic acidosis is not a valid reason to discontinue metformin. In fact, I think it is inappropriate to ever postpone or cancel surgery simply because the patient inadvertently took metformin on the morning of surgery. Some may argue that patients with renal insufficiency are at higher risk of lactic acidosis from metformin use on the morning of surgery, but keep in mind that renal insufficiency is a relative contra­indication to metformin use in the first place. Unless the patient is scheduled for a bilateral nephrectomy, his or her renal function is not going to be acutely reduced enough to enable a morning dose of metformin to cause lactic acidosis.

Dr. Cohn: Additionally, in a recent study of patients undergoing coronary artery bypass graft surgery (CABG), there was no increased risk of in-hospital morbidity or mortality in patients who received metformin on the morning of surgery,⁷ although I typically stop it 24 hours before major surgery.

Question 2.4: With respect to statin therapy, which course would you choose preoperatively?

A. Start a statin at a low dose

B. Start a statin at an intermediate dose

C. Start a statin at a high dose

D. Do not start a statin

Dr. Cohn: The answer to this question is not clear cut. The reason not to start a prophylactic statin would be the lack of evidence of benefit in patients undergoing noncardiac, nonvascular surgery, although there is evidence of potential benefit in patients undergoing vascular surgery.* The arguments in favor of starting a statin are that this patient has independent indications for a statin and the planned surgery is a high-risk procedure.

(* Editor’s note: In the time since this summit, results of the DECREASE-IV trial were published [Dunkelgrun et al, Ann Surg 2009; 249:921–926], showing a statisically nonsignificant trend toward improved outcomes at 30 days with fluvastatin in intermediate-risk patients undergoing noncardiovascular surgery.)

In cohort studies, perioperative death rates have been lower in statin recipients than in those not taking a statin.⁸ In the Dutch Echographic Cardiac Risk Evaluation Applying Stress Echo III (DECREASE III), which randomized noncardiac vascular surgery patients to perioperative fluvastatin or placebo, rates of MI and the composite end point of nonfatal MI or cardiovascular death were significantly lower in the statin group than in the placebo group.⁹

Question 2.5: Which of the following cardiac tests would you order preoperatively?

A. Exercise ECG

B. Dobutamine stress echocardiogram

C. Dipyridamole nuclear imaging

D. Coronary angiography

E. No further cardiac testing

Dr. Cohn: I wouldn’t do any cardiac testing since this patient needs surgery for his malignancy and the results of any testing would be highly unlikely to change management, in terms of canceling the surgery. This approach is consistent with the 2007 guidelines on perioperative cardiovascular evaluation for noncardiac surgery issued by the American College of Cardiology (ACC) and the American Heart Association (AHA).¹⁰

Dr. Sweitzer: I would differ on this question. This patient has not been evaluated adequately for his coronary artery disease. He has poor functional capacity that complicates assessment of his symptoms. He also has diabetes, so he is more likely to have silent myocardial ischemia. At age 78, he is understandably concerned about his survival: radical cystectomy is a major operation associated with significant blood loss, fluid shifts, and a long-term recuperative state. In this case, a cardiac evaluation may change management, not in terms of considering coronary revascularization before the surgery, but in terms of affecting the assessment of his chance of surviving this major operation, his life span following the operation, and his quality of life. For example, a highly positive dobutamine stress echo­cardiogram or certain wall motion abnormalities would suggest that he might not be protected even by optimal perioperative medical management.

Question 2.6: Which of the following would you do pre­operatively to assess pulmonary risk?

A. Obtain pulmonary function tests

B. Order a sleep study

C. Both

D. Neither

Dr. Sweitzer: There is no evidence supporting routine pulmonary function tests for patients undergoing procedures other than lung resection. If obstructive sleep apnea were suspected, I would order a sleep study only if I had access to one quickly to avoid delaying the surgery. Cancer surgery should never be delayed to get a sleep study. However, if this patient were seen in the primary care clinic, I would order a sleep study and, if indicated, put him on continuous positive airway pressure (CPAP). Whether or not preoperative CPAP makes a difference hasn’t been shown. No randomized controlled trials have been conducted, but there are some suggestions that the risks of ischemia and atrial arrhythmias in patients with known coronary artery disease can be reduced with CPAP. It is not always easy to initiate CPAP postoperatively because the number of CPAP machines is limited and titration by a respiratory technician is required, which is typically done in a sleep lab.

How the case was actually managed

Neither an HbA_1c measurement nor a lipid profile was ordered preoperatively, for lack of supportive evidence. The patient was continued on his beta-blocker and the dosage was increased sufficiently to control his blood pressure and heart rate. Metformin was continued, and statin therapy was begun preoperatively in light of the patient’s independent indications for it and the high-risk nature of the procedure. Stress testing was not ordered, in light of the lack of indication, given the patient’s stable angina. The patient refused a sleep study. The operation was lengthy and involved significant blood loss. The patient had a complicated postoperative course and ultimately died from multiorgan failure.