Abstract
For any anesthetic, the anesthesiologist must consider the patient’s medical history while assessing the likelihood that the anesthetic and procedure may lead to a detrimental outcome. Although costly, anesthesiologists would ideally have all preoperative workup and testing completed prior to proceeding with an anesthetic. However, patients commonly present without having sufficient preoperative testing and lab work completed. In these situations, the anesthesiologist must exercise critical thinking and judiciously determine whether testing is required prior to the procedure. The threat of legal consequences and subsequent ordering of unnecessary testing has led to the increase in health care costs and spending. Despite this, practitioners should apply clinical knowledge and practice guidelines to direct their preoperative workup.
Keywords
preoperative testing, health care cost, risk assessment, preanesthetic evaluation, adverse outcomes
Case Synopsis 1
A 64 – year-old man with low activity tolerance, a history of hypertension, obesity, and vague episodes of epigastric discomfort is scheduled for elective open partial colectomy. No preoperative electrocardiogram is obtained. The patient subsequently sustains a perioperative myocardial infarction secondary to undiagnosed coronary artery disease.
Case Synopsis 2
A 73-year-old woman who is taking several diuretic medications is scheduled for elective hip arthroplasty. An outside provider obtained a chemistry and electrolyte panel and faxed the results to your surgeon’s office. On the day of surgery the results are not available. A discussion ensues about the need to obtain a repeat test. The test is finally found and the plasma sodium is 124 mEq/L. Surgery is postponed.
Problem Analysis
Definition
Effective preoperative test selection may be enhanced by knowing how outcomes are affected by the performance or omission of testing. The following are four important unwanted outcomes:
- 1.
Misinterpretation of test significance by providers or patients
- 2.
Adverse medical events from incorrect actions as a result of a test, or failing to act on test results
- 3.
Increased cost of care from the test, retesting, or subsequent follow-up tests or procedures
- 4.
Litigation for any reason related to the above
Simply knowing the result of a preoperative test cannot ensure a good outcome. Moreover, the accuracy and usefulness of a test depend greatly on its sensitivity and specificity, combined with the frequency of the condition in the population. In addition, considering the pretest probability of disease for that particular patient will add greatly to the utility of testing.
Recognition
Tests may not be used for clinical care if they are not performed, not reviewed, or not available. A more difficult question is whether a specific test was actually indicated, if performed. Hindsight may not be adequate to determine actual preoperative need. Only well-structured clinical studies and logical analysis can provide direction for clinicians who wish to provide evidence-based care.
Risk Assessment
Patients are at risk for adverse outcomes when tests are not done owing to an oversight, inadequate history and physical examination, inadequate guidelines, or inappropriate emphasis on cost reduction. Process failures also occur when tests are done but the results are unavailable or lost or when providers fail to review the results before an anesthetic is administered. Depending on a patient’s medical history and physical status, the lack of appropriate preoperative testing may place the patient at a higher risk of an adverse outcome. However, healthy patients undergoing routine surgery do not need a battery of preoperative tests, and perhaps none at all.
Implications
If a test is mandated by policy but is not done, the patient’s outcome may or may not be affected. For example, if a patient has a slightly elevated serum calcium level or is slightly anemic, for most operations, adverse perioperative outcomes are unlikely.
However, if a patient has severe, unrecognized coronary disease and sustains a perioperative myocardial infarction, there will definitely be more medical care required, greater time spent in the hospital, increased costs, and possible long-term disability or risk of death. Further, emotional, professional, economic, and medicolegal risks for the providers will be increased.
Not factored into this discussion, but important, is how abnormalities discovered preoperatively could lead to primary or specialty care that improves long-term health.
Management
If a test is found to be missing before an anesthetic is begun and the surgery is elective, the anesthesiologist and the surgeon must determine whether internal or external policies absolutely mandate the test. If so, the test should be obtained, or the providers must justify in the medical record why they were willing to proceed with anesthesia or surgery without the test results. Of course, for emergent or urgent procedures, physicians should always weigh the expected benefits of a test against the risks of delay.
If the test is discovered to be missing after anesthesia or surgery has commenced, the providers must determine whether obtaining the test result at this point will make any difference or whether the procedure should be terminated (this is fortunately a rare occurrence). Tests may, of course, be obtained during the provision of an anesthetic and serve the same purpose as a preoperative test, if only needed for postoperative care. This is not true, however, if a preoperative test would have changed the decision to proceed with the procedure or if the test would have substantially affected the initial anesthetic plan. An example of this might be the finding of an elevated prothrombin time before the administration of a neuraxial anesthetic.
If a test is discovered to be missing after surgery, is there a need to obtain the test? It may actually be wise to do so if postoperative or long-term medical management would be altered by the results.
Prevention
Value-Based Medical Care
If the absence of a test leads to an adverse outcome, the system should be reexamined to prevent future omissions. Caution should be used, however, in ascribing causality. Bad outcomes do not necessarily mean that more defensive testing is indicated. We must consider whether testing really would have made a difference in the outcome. In addition, short-term and long-term benefits versus the potential harmful effects of testing should be considered. This is consistent with the concept of value-based anesthesia care. Complex cost-benefit analysis may be needed; time has actual value in medicine, and a seemingly more costly process may be less expensive in the long run versus a less costly but lengthier process.
Evidence-Based Medical Care
Ideally, all tests should be ordered using the principle of evidence-based medical care. Many articles have been written about preoperative assessment, but few cite sufficient rigorous evidence to offer definitive answers for all our patient populations. Recently an updated American Society of Anesthesiologists task force report again found that there were insufficient scientific outcome studies to support a specific scheme for preoperative testing other than sound medical practice based largely on a careful history and physical examination.
Focused Preoperative Testing
A good use of the history and physical examination is to focus preoperative testing. However, it is important to note that many symptoms or signs may be highly sensitive but are not highly specific indicators of problems. Interobserver variability is often high. In addition, the value of the medical history depends on the adequacy of the past medical record and on the patient’s reliability and communication skills. Taking a good history or ordering tests may not predict poor outcomes for some conditions, especially bleeding. Other tests are associated with poorer outcomes, such as hyponatremia.
The American Society of Anesthesiologists Preoperative Evaluation guideline states the following:
Preoperative tests, as a component of the preanesthesia evaluation, may be indicated for various purposes, including but not limited to (1) discovery or identification of a disease or disorder that may affect perioperative anesthetic care; (2) verification or assessment of an already known disease, disorder, medical or alternative therapy that may affect perioperative anesthetic care; and (3) formulation of specific plans and alternatives for perioperative anesthetic care.
Nonselective Versus Selective Testing
Most schemes for preoperative testing distinguish between nonselective and selective testing. The former requires that every patient be tested or screened, even if asymptomatic. Although this approach was commonly used in the past, few recommend it today. Selective testing requires that certain criteria be used to determine the need for testing.
- •
Patient factors. These include, but are not limited to, symptoms, age, past medical history, gender, and physical findings. Other factors, such as the ability to obtain a reliable history or perform an adequate examination, should also be considered.
- •
Type of surgery. Baseline values may be required because the surgery itself will cause anatomic or physiologic derangements.
Nonetheless, some surgeries are so low risk that cardiac or other (nonsurgical) complications are rare. Eye surgery has been touted as a procedure that does not benefit from most testing, as long as the patient’s condition is stable. Some have called for the elimination of testing before most outpatient surgery. With the trend toward scheduling patients with more comorbidities for more complex outpatient surgery, only using the designation of outpatient surgery to eliminate testing may not be appropriate.
Higher-complexity procedures that have a more profound impact on patient physiology may need baseline tests to follow perioperative changes. However, these should be ordered sparingly and with careful reasoning.
Practice Guidelines
The Institute of Medicine defines clinical practice guidelines as follows: “Clinical practice guidelines are statements that include recommendations intended to optimize patient care that are informed by a systematic review of the evidence and an assessment of the benefits and harms of alternative care options.” Guidelines should ideally be based on good-quality studies and should follow principles similar to the American College of Cardiology methods. However, lacking rigorous outcome studies, criteria are often based on local and national expert opinion and experience. Policies or guidelines need to be constantly updated to be credible, and local consensus is an absolute necessity. Guidelines may be locally empiric or more complex and derived from widespread consensus. Examples of general guides include the 2016 NICE guidelines and the National Clearing House Perioperative Guidelines. The American College of Cardiology/American Heart Association 2014 guideline update can help determine the need for cardiac testing based on criteria that rely heavily on the history and physical examination. In the future there may be increasing use of screening biomarkers, such as B-type natriuretic peptide (BNP) or high-sensitivity troponin assays to stratify perioperative cardiac risk.
Many guides simply recommend testing “as indicated by history and examination.” However, such nondirective guidelines may result in either more or fewer tests than needed, especially if nonanesthesia providers are responsible for ordering the tests. Guidelines may decrease inappropriate testing, but a recent survey found that clinicians often go outside recommendations to reassure patients or themselves.
Importantly, there are good reasons to omit nonindicated tests. Even if the tests were to cost nothing, they can do harm by leading to further testing, inappropriately altering case management, giving the anesthesiologist and surgeon a false sense of security, and even distracting them from more important issues. Performing tests when there is no plan to review them before surgery is medically useless and legally dangerous.
The 2012 American Society of Anesthesiologists Preoperative Evaluation guideline recommends testing based on patient and procedure factors, rather than asymptomatic screening. To quote the guide regarding the case study mentioned earlier: “In asymptomatic or nonselected patients, coagulation abnormalities (i.e., bleeding time, prothrombin time, partial prothrombin time, or platelet count) were reported in 0.06%–21.2% of patients and led to cancellations or changes in management in 0.0%–4.0% of cases with abnormal findings (Category B2 evidence).” Although we cannot be sure how often reported changes in management affected outcomes in published studies on coagulation testing, it would seem that it should be uncommon to order coagulation tests without a specific indication or need.
Recent efforts to reduce unnecessary medical interventions include the “Choosing Wisely” initiative, with many professional societies participating. Two pertinent statements from the American Society of Anesthesiologists are included in Box 21.1 .
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