Previous cardiac event
Congestive cardiac failure within 30 days
Chronic steroid use
Ascites within 30 days
Systemic sepsis within 48 h
Acute renal failure
Based on the answers, the risk factors for a specific procedure, in this illustration, colectomy, are obtained. The predicted average length of hospital stay is then displayed
Average patient risk (on a sliding scale)
Chance of outcome (below, average, above)
Any complication (includes return to OR)
Surgical site infection
Urinary tract infection
While many surgical factors are taken into consideration, anesthetic factors are not addressed. History of previous difficult intubation or tracheostomy, or problems specific to anesthesia such as malignant hyperthermia or certain allergies might well impact outcome and hence risk.
All the medications that a patient is taking should be documented, including over-the- counter drugs such as non-steroidal anti-inflammatory agents (NSAIDs) and especially herbal preparations. The latter, while considered natural and thus safe, may indeed have many interactions (◘ Box 24.1). Problems arise mainly in interference with the cytochrome p450 isoenzymes (CYP). Inhibition of this system decreases metabolism and increases drug levels and duration of action. Induction, on the other hand, increases metabolism, while decreasing the effectiveness of the drug and its duration of action. Of most concern is the interference with CYP 3A4 in the liver as >50% of current prescription drugs depend on this system. Some of the more commonly used herbal substances and their varied effects on the CYP system is shown in ◘ Table 24.3.
Many herbs affect the CYP system, some increasing the effectiveness of drugs, even to toxic levels while others prevent absorption and thus render the drug essentially useless
Chamomile, grapefruit, ginko, kava
Garlic, ginko, St. John’s wort
Chamomile, ginko, grapefruit
St. John’s wort
Feverfew, grapefruit, kava
Ginko, St. John’s wort
Feverfew, ginko, grapefruit, kava
St. John’s wort
Ginko, goldenseal, kava
Whether or not medications should be continued during the perioperative period should be made on a case-by-case basis for each individual patient by the patient care team. Of major concern are the cardiac medications. The most recent ACC/AHA guidelines, however, can provide some guidance pertaining to cardiac medications that may directly affect perioperative morbidity and mortality .
Box 24.1 Several interactions have been identified with herbal medications and anesthesia
Echinacea offsets immunosuppression, inhibits hepatic microsomal enzymes (HME)
Garlic augments heparin, NSAIDs, and increases perioperative bleeding.
Ginger increases bleeding time
St. John’s wort reacts with MAO inhibitors, tetracycline
Kava-kava reacts with ethanol, excessive sedation
Feverfew inhibits platelet activity
Ephedra interacts with inhalation anesthetics
Ginseng causes hypertension, hypoglycemia, reacts with MAO inhibitors, increases bleeding
Beta Blocker Therapy
Several studies have examined the risks and benefits of perioperative beta blocker therapy. Although each study was designed to answer the same question, most resulted in different answers. It does appear that beta blocker therapy in the perioperative period decreases the number of cardiac events, such as myocardial infarction (MI). However, this benefit comes at the cost of increased hypotension, stroke, and, in some studies, composite death. The most recent systematic review examining the data came with the following recommendations :
Beta blockers should be continued in patients undergoing surgery who have been on beta blockers chronically.
The management of beta blockers after surgery may be guided by clinical circumstances independent of when the agent was started.
In patients with intermediate or high cardiac risk it may be reasonable to begin perioperative beta blocker therapy. If the decision is made to begin beta blocker therapy on a patient in the perioperative period, it is recommended that therapy be initiated at least 1 day prior to surgery, and preferably at least 2–7 days prior. Beginning beta blockers on the day of surgery is likely ineffective and may be harmful. Common sense would dictate that beginning a medication that could have significant changes in myocardial contractility and systemic blood pressure should occur days prior to surgery, such that the tolerability of the medication and its dose can be assessed by the patient and the physician. While there is no direct data to support this conclusion, it likely is best practice.
Statin therapy has been shown to be effective for primary and secondary prevention of cardiac events. Although most of the data related to statin therapy come from observational trials, the composite power suggests a protective effect on the preoperative use of these agents in either vascular surgery or high-risk patient populations . The most recent guidelines therefore recommend that those on statins continue their therapy in the perioperative period. They also allow for the initiation of therapy in patients undergoing vascular surgery, as well as patients with clinical indications undergoing medium- or high-risk procedures. The mechanism of benefits from perioperative statin therapy are unknown, but are likely related to pleotropic, lipid lowering effects, as well as anti-inflammatory effects. Additionally, it is not known when is the optimal time to begin therapy, nor is it clear what the duration of therapy should be.
Early data on the role of alpha-2 agonists such as clonidine and mivazerol suggested that the perioperative use of these agents, especially in vascular surgery was protective. The POISE-2 (PeriOperative ISchemic Evaluation-2) trial—a large, multicenter, international, blinded study—was unable to demonstrate the benefit of clonidine. Additionally, it was found that clonidine use in the perioperative period was associated with an increase in the rate of nonfatal cardiac arrest and clinically significant hypotension. It is therefore not recommended to use alpha-2 agonists in the perioperative period for the prevention of cardiac events. Patients who are on alpha-2 agonists for other indications (such as hypertension) should continue their dose of medication; or ideally, be weaned off their medication and started on other therapies prior to surgery. The abrupt discontinuation of these medications can result in rebound hypertension, headache, agitation, and tremor.
Calcium Channel Blockers
The most current guidelines have no recommendations for starting calcium channel blockers in the perioperative period. A meta-analysis from 2003 examined the use of calcium channel blockers in patients with coronary disease and found trends toward reduced death and MI. It should be noted that these differences were mostly attributable to the use of diltiazem. Neither dihydropyridines nor verapamil had effects on mortality or MI; however, the use of either verapamil or diltiazem seemed to be protective for the development of perioperative supraventricular tachycardia (SVT). The authors note that the results are trends and that larger more robust studies are needed to confirm the results. As such, although it would be prudent to continue these medications in the perioperative period it is not recommended to begin therapy unless otherwise indicated.
Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers
Approved for multiple indications from hypertension to prevention of diabetic nephropathy, ACE andangiotensin receptor blockers (ARBs) are some of the most commonly prescribed medications. Perioperative data on the risk/benefit profile of continuation of these medications is limited mostly to observational data. The largest study examined almost 80,000 patients (of which 13% were on ACE-I) and found that patients on therapy had an increased frequency of intraoperative hypotension. This has been found in other studies as well, with one showing an incidence of hypotension of 50% in patients on therapy. Despite the increase in hypotension, there appears to be no increased incidence of death, MI, or renal failure. The evidence on discontinuation of these medications prior to surgery is poor. There is data, however, on the risks of not restarting these medications in the perioperative period, which seems to be the greatest risk of discontinuation. In fact, maintaining the continuity of these medications in the setting of treatment for heart failure or hypertension is supported by other guidelines. Additionally, a more recent cohort study including 30,000 patients found an increased risk of mortality in patients in whom restarting ARB therapy was delayed. Due to the lack of demonstration of real harm to patients who continue therapy in the perioperative period as well as the potential risks of discontinuation, continuing these medications in the perioperative period is reasonable. If ACE/ARB therapy must be withheld, it should be restarted as soon as possible.
Recommendations to discontinue oral diabetic medication remain controversial. While elevated blood sugar levels have been shown to retard wound healing, an ideal blood sugar level has not been determined. While many laboratory scales consider hyperglycemia to be values above 120 mg/dl, it is probably more important to consider the individual and the level at which he most usually functions. Thus, values of 150–170 mg/dl may be considered normal for many. Should testing indicate values exceeding 180 mg/dl, oral medications should be discontinued and an infusion of regular insulin commenced perioperatively. Further evaluation by an endocrinologist is indicated with repeated blood glucose checks.
24.2.4 Cardiac Evaluation
While nonspecific abnormalities are found on EKG tracings in about 30% of patients, the finding rarely predicts postoperative complications and is usually insignificant.
As part of Choosing Wisely and recommendations from the ACC/AHA, the need for further cardiac testing prior to non-cardiac surgery is limited to determination of 1 of 4 criteria :
Unstable coronary syndrome (MI, unstable angina)
Decompensated heart failure (New York Heart Association [NYHA] class IV or worsening disease or new onset)
Significant dysrhythmias; high grade or Mobitz II atrioventricular (AV) block, 3rd degree AV block, symptomatic ventricular dysrhythmias
Severe valvular disease
Stress testing and cardiac consultation should only be requested if any of the above findings can be made on physical examination.
24.2.5 Airway Assessment
Evaluation of the airway begins with a comprehensive history and physical examination. It is very important to ascertain if the patient has been told of any difficulty with intubation in the past and if he/she had a sore throat after a procedure. A short list of factors that may be indicative of a difficult airway are shown in ◘ Table 24.4.
Many factors may contribute to a difficult airway and can usually be elicited by careful history and physical examination
Intraoral abscess/tonsillar enlargement
Cervical cord injuries
Temporo-mandibular joint disease
Treacher Collins syndrome