Beeline to Spine
- Understand the elements of preoperative medical evaluation.
- Appreciate the limited role for preoperative laboratory testing.
- Appreciate the importance of communication and collaboration between providers before surgery.
- Discuss the value of preoperative clinics.
Case & Commentary: Part 1
An 83-year-old man with coronary artery disease, mild heart failure, a history of repaired abdominal aortic aneurism (AAA), and prior lumbar disk disease (status post L5-S1 fusion) was scheduled for a fusion-augmentation surgery by orthopedics. The patient noted a bulging mass in the middle of his abdomen a few months prior to surgery but did not report this to his providers. Laboratory tests sent for a voluntary medical research study showed an elevated alkaline phosphatase to nearly 800 U/L. These results were reviewed by his primary physician, but no action was taken.
Preoperatively, the patient was evaluated by both the anesthesiology and surgery teams. Given the prior AAA repair, the patient underwent surgery in the supine position. The fusion augmentation was uneventful, and he was discharged home.
The decision to undergo major surgery requires a careful assessment of the risks and benefits of the proposed procedure. This assessment must appreciate the reality that surgery is a morbid event. For example, the mean 30-day mortality rate in a recent study of 5878 patients undergoing major surgery was 1.5%.(1) Perioperative mortality rates, stratified by American Society of Anesthesiologists' (ASA) Physical Status Class for class I through V, were 0%, 0.2%, 2.2%, 15.2%, and 70%.(1) Postoperative medical complications represent an important source of this morbidity and mortality. The most important medical complications are cardiac, pulmonary, and venous thromboembolic. Preoperative medical evaluation should include a consideration of each of these three sources of risk.
More broadly, clinicians performing a routine preoperative medical evaluation should address several issues. The first is to identify factors that would increase the risk of perioperative complications above baseline and to stratify risk for the principal complications. The second issue to consider is whether preoperative laboratory testing would add to this risk assessment or potentially uncover important risks that would have escaped clinical detection. The next step is to recommend strategies to reduce these risks to the extent that they are modifiable. Finally, the preoperative medical evaluation provides an opportunity for collaboration between medicine, surgery, and anesthesia colleagues. Instances in which such collaboration is particularly important include identification of a previously unrecognized important risk factor, a determination that the risks of the surgery may potentially exceed the benefits, or a recommendation for risk reduction strategies that include the intraoperative and immediate postoperative period.
A careful history is the most important element of the preoperative evaluation. This history seeks evidence for major risk factors for medical complications as well as factors that would influence anesthetic technique and management. Many institutions have developed standardized checklist forms to facilitate the anesthesiologist's preoperative evaluation. Table 1 provides one published questionnaire and the degree of concordance between patient responses and an evaluation by an anesthesiologist.(2) The medical consultant typically does not use a standardized questionnaire but focuses in detail on the impact of established chronic illnesses and potential risk factors for major postoperative medical complications. Guidelines exist to estimate risk of cardiac, pulmonary, and venous thromboembolic complications.(3-6)
Routine preoperative laboratory testing adds little to the clinical estimate of risk. Abnormal tests are uncommon, and most can be predicted on the basis of known medical problems. For example, a large review of a broad array of potential tests found that the incidence of abnormalities that influenced preoperative management ranged from 0%–3% (Table 2).(7) In all cases, the negative likelihood ratio approached one (meaning that a normal test result does not materially reduce the risk of medical complications). The impact of positive test results is modest; positive likelihood ratios range from 0–4.3. Based on these types of analyses, most institutions in recent years have reduced the number of required preoperative tests. For example, the National Institute for Clinical Excellence (NICE) in Great Britain published recommended standards in 2003.(8) If we apply these standards to our patient, he would receive a complete blood count, renal function tests, and an electrocardiogram. If we apply the recommendations of the above mentioned systematic review (7), he would also receive a chest x-ray.
In this 83-year-old patient, his age and comorbidities would put him at higher risk for cardiac complications, and to a lesser extent, pulmonary problems (back surgery is an intrinsically low-risk procedure for pulmonary complications). According to the Revised Cardiac Risk Index, his estimated risk for postoperative cardiac complications would be 6.6% (9), representing the source of his greatest potential morbidity. His preoperative assessment, including recommendations for risk reduction strategies, should focus on this area. He should also receive appropriate prophylaxis to reduce the risk for surgical site infection (SSI) (10) and venous thromboembolism (VTE).(6) In most institutions, these two areas of prophylaxis are standardized according to a particular surgical specialty and the nature of the specific procedure. In such a scenario, every patient would receive the same SSI and VTE prophylaxis unless a specific contraindication existed. For example, according to standardized, preprinted, routine preoperative orders for back surgery, he may receive a single intravenous dose of 1 gram of cefazolin within 1 hour before the incision. Thus, the responsibility in this case for ensuring that the patient receives SSI and VTE prophylaxis would normally fall to the surgeon.
Case & Commentary: Part 2
One week later, the patient was readmitted with frank jaundice, abdominal pain, and diarrhea. Physical examination revealed a 4x4 cm, easily palpable mass protruding from his mid-abdomen. Computed tomography (CT) scan revealed a widely metastatic pancreatic cancer. There was massive tumor burden along the peritoneum and adjacent to stomach, liver, and bowels. A cancer antigen (CA) 19-9 level was extremely high. When told of his diagnosis of metastatic cancer, the patient immediately said that he wished he had never undergone the spinal surgery.
This response from the patient is completely expected and reasonable. Had he known that he had unresectable pancreatic cancer, with a likely life expectancy of less than 6 months, the most reasonable approach would have been to cancel elective back surgery. Instead, he underwent unnecessary surgery that conferred risk, took time from his remaining months of life, and resulted in a potential for postoperative pain and complications.
There were several opportunities to prevent this error. The patient had abnormalities in all three elements of the preoperative evaluation: the history, physical examination, and laboratory tests. A careful history that included an open-ended question such as "Do you have any other symptoms or concerns about your health that we didn't already discuss today?" may have captured his concern about the abdominal mass.
According to this case scenario, the abdominal mass was easily palpated; it almost certainly would have been of similar size during his preoperative evaluation. However, I can't fault his physicians on this point. A "complete" physical examination, such as that which would be performed as part of a periodic health exam in a primary care setting, is not required before elective surgery. Examination of the abdomen would not normally be part of the minimum required physical examination before back surgery. A suggested minimum examination includes vital signs and an assessment of the airway, chest, and heart.(11) Additional examination elements would be based on his medical history. So we fall back to the history: did the patient mention the mass or abdominal pain? If he had, each involved physician would have had an opportunity to identify the mass on examination.
Should the elevated alkaline phosphatase have been a clue to his underlying cancer? Unfortunately, in the fragmented system of American health care, the operative team's ability to access laboratory results (or other key patient data) often depends on whether this test was part of the patient's hospital medical record and whether his primary care doctor used the hospital laboratory for blood tests. If a test was performed by an outside laboratory as part of the medical research study, as in this case, only a paper copy may have been in the doctor's office records. If the primary care doctor was community based, and not part of hospital-based practice at the site where his surgery was planned, this test result may not have been available to other physicians involved in his care. Obviously, this situation begs for a unified medical record [such as if the community-based primary care physician used an electronic medical record (EMR) that was part of the hospital's network] or other methods for patient data to cross silos of care.
Communication in the preoperative setting is particularly challenging when physicians practice in different sites and have no access to each other's medical records. In such a setting, each doctor has a responsibility to follow through on any identified factors that may increase risk. This may require a phone call or an email communication to be sure that all doctors are "on the same page." Mandatory formal preoperative assessment clinics are one strategy to identify patients who need additional preoperative evaluation, optimize medical conditions, and potentially improve outcomes. In one study, for example, anesthesiologists developed a preoperative assessment clinic for patients undergoing vascular surgery, a procedure with a particularly high morbidity and mortality rate.(12) Among 234 patients seen in this clinic, the anesthesiologist identified 26 patients who required further evaluation or were unsuitable for surgery due to significant comorbidities. Despite a modest sample size, the authors found a significant reduction in mortality rates among patients undergoing infrarenal aneurysm repair who visited the preoperative clinic when compared to those who received usual care (4.8% vs. 14.5%). In another study at Brigham and Women's Hospital in Boston, 565 of 5083 patients seen in a preoperative clinic required further information regarding known medical problems, and the authors identified an additional 115 patients with new medical problems.(13) Among the patients with new problems, 20% required review of previous medical records or test results (as could have potentially been the case in this patient) and 80% required additional testing or consultation.
Patients at highest risk for poorly coordinated care are those with multiple physicians, those without a primary care physician who is actively involved in their care, those who receive care from doctors who belong to different health delivery systems with separate information technology systems, those from disadvantaged settings who receive much of their primary care in emergency departments, and those who are less medically literate and are thus less able to describe their detailed medical histories.
Case & Commentary: Part 3
Review of the preoperative assessment by anesthesia and orthopedics revealed no mention of an epigastric mass nor of the markedly abnormal alkaline phosphatase.
Unfortunately, no clear guidelines or written policy statements articulate the ultimate responsibility of each physician before surgery. As a generally accepted standard of care, the consulting primary care physician would be responsible for evaluating all factors that play into the risk-benefit considerations before surgery. In most instances, the primary care physician would have access to the most complete set of medical records and, by virtue of a long-term relationship with the patient, would be most likely to know all details of the relevant past medical history.
With regard to laboratory data (such as the alkaline phosphatase), evidence suggests that a normal test result obtained within the past 4 months can be used as a preoperative test as long as there has been no change in the clinical status of the patient.(14) The primary care physician is responsible for reviewing recent laboratory tests to determine if any results impact preoperative assessment, and to determine which, if any, should be repeated before surgery.
Alkaline phosphatase would never be a routine preoperative test.(7) However, the abnormal finding of a markedly elevated result in this patient would require further evaluation, independent of the planned upcoming surgery. In an elderly man, cancer (pancreatic, biliary, liver, or metastatic disease to liver) would be the most likely cause of an asymptomatic elevation of alkaline phosphatase. Gallstone disease or intrahepatic cholestasis would each be less likely. It would be necessary to further evaluate the patient and exclude cancer before any consideration of elective surgery. The primary care physician not only failed to consider the impact of a very high alkaline phosphatase on the risk for surgery, he or she failed to undertake an appropriate evaluation independent of the patient's planned back surgery.
The anesthesiologist conducting a preoperative evaluation would normally not be expected to undertake a similarly extensive evaluation nor to obtain office notes from the primary care physician. The anesthesiologist's preoperative evaluation would focus on factors that increase anesthetic risk or modify anesthetic technique. The surgeon would usually defer to the primary care physician regarding medical appropriateness for surgery and the need for any further preoperative medical evaluation. Having said this, it would still have been possible for either of these physicians to have identified this cancer before surgery by asking an open-ended question, such as "Do you have any other health issues or concerns that you would like to discuss before surgery?" or by performing a physical examination.
This case illustrates the importance of a complete preoperative evaluation, the need for meticulous communication among providers, and the potential pitfalls of non-centralized medical information. Dedicated preoperative clinics may reduce the risk of poor outcomes by uncovering risk factors and by recommending additional evaluation or evidence-based risk reduction strategies. The history and physical examination remain the cornerstones of preoperative evaluation.
- Preoperative medical evaluation requires a thorough history and physical examination, using open-ended questions.
- Laboratory testing plays a limited role in risk stratification.
- Communication and collaboration among providers before surgery are critical.
- Preoperative clinics may aid in identifying risk factors for postoperative complications and may improve outcomes.
- Patients should proceed to surgery only if the benefits exceed the risk.
Gerald W. Smetana, MD Associate Professor of Medicine, Harvard Medical School Division of General Medicine and Primary Care, Beth Israel Deaconess Medical Center
Faculty Disclosure: Dr. Smetana reported serving as course director for Harvard Medical International—Novartis Schweiz. His commentary does not include information regarding investigational or off-label use of products or devices. All conflicts of interest have been resolved in accordance with the ACCME Updated Standards for commercial support.
1. Davenport DL, Bowe EA, Henderson WG, Khuri SF, Mentzer RM Jr. National Surgical Quality Improvement Program (NSQIP) risk factors can be used to validate American Society of Anesthesiologists Physical Status Classification (ASA PS) levels. Ann Surg. 2006;243:636-644. [go to PubMed]
2. Hilditch WG, Asbury AJ, Jack E, McGrane S. Validation of a pre-anaesthetic screening questionnaire. Anaesthesia. 2003;58:874-877. [go to PubMed]
3. Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery). J Am Coll Cardiol. 2002;39:542-553. [go to PubMed]
4. Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2006 guideline update on perioperative cardiovascular evaluation for noncardiac surgery: focused update on perioperative beta-blocker therapy: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Update the 2002 Guidelines on Perioperative Cardiovascular Evaluation for Noncardiac Surgery): developed in collaboration with the American Society of Echocardiography, American Society of Nuclear Cardiology, Heart Rhythm Society, Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society for Vascular Medicine and Biology. Circulation. 2006;113:2662-2674. [go to PubMed]
5. Qaseem A, Snow V, Fitterman N, et al. Risk assessment for and strategies to reduce perioperative pulmonary complications for patients undergoing noncardiothoracic surgery: a guideline from the American College of Physicians. Ann Intern Med. 2006;144:575-580. [go to PubMed]
6. Geerts WH, Pineo GF, Heit JA, et al. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126(suppl 3):338S-400S. [go to PubMed]
7. Smetana GW, Macpherson DS. The case against routine preoperative laboratory testing. Med Clin North Am. 2003;87:7-40. [go to PubMed]
8. Carlisle J, Langham J, Thoms G. Editorial I: Guidelines for routine preoperative testing. Br J Anaesth. 2004;93:495-497. [go to PubMed]
9. Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999;100:1043-1049. [go to PubMed]
10. Bratzler DW, Hunt DR. The surgical infection prevention and surgical care improvement projects: national initiatives to improve outcomes for patients having surgery. Clin Infect Dis. 2006;43:322-330. [go to PubMed]
11. American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Practice advisory for preanesthesia evaluation: a report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology. 2002;96:485-496. [go to PubMed]
12. Cantlay K, Baker S, Parry A, Danjoux G. The impact of a consultant anaesthetist led pre-operative assessment clinic on patients undergoing major vascular surgery. Anaesthesia. 2006;61:234-239. [go to PubMed]
13. Correll DJ, Bader AM, Hull MW, Hsu C, Tsen LC, Hepner DL. Value of preoperative clinic visits in identifying issues with potential impact on operating room efficiency. Anesthesiology. 2006;105:1254-1259. [go to PubMed]
14. Macpherson DS, Snow R, Lofgren RP. Preoperative screening: value of previous tests. Ann Intern Med. 1990;113:969-973. [go to PubMed]
Table 1. Sample Preoperative Screening Questionnaire and Correlation with Anesthesiologist's Evaluation
|1. Do you usually get chest pain or breathlessness when you climb up two flights of stairs at normal speed?||Good|
|2. Do you have kidney disease?||Moderate|
|3. Has anyone in your family (blood relatives) had a problem following an anesthetic?||Undetermined|
|4. Have you ever had a heart attack?||Excellent|
|5. Have you ever been diagnosed with an irregular heartbeat?||Good|
|6. Have you ever had a stroke?||Excellent|
|7. If you have been put to sleep for an operation, were there any anesthetic problems?||Undetermined|
|8. Do you suffer from epilepsy or seizures?||Yes|
|9. Do you have any problems with pain, stiffness, or arthritis in your neck or jaw?||Excellent|
|10. Do you have thyroid disease?||Excellent|
|11. Do you suffer from angina?||Good|
|12. Do you have liver disease?||Yes|
|13. Have you ever been diagnosed with heart failure?||Yes|
|14. Do you suffer from asthma?||Excellent|
|15. Do you have diabetes that requires insulin?||Yes|
|16. Do you have diabetes that requires tablets only?||Yes|
|17. Do you suffer from bronchitis?||Excellent|
*Criterion validity is the degree to which patient responses to the questionnaire agree with the anesthesiologist's evaluation. "Yes" indicates adequate criterion validity.
Reprinted with permission from Blackwell Publishing. Adapted with permission from Dr. Hilditch. In: Hilditch WG, Asbury AJ, Jack E, McGrane S. Validation of a pre-anaesthetic screening questionnaire. Anaesthesia. 2003;25:874-877.
Table 2. Recommendations for Laboratory Testing before Elective Surgery*
|Test||Incidence of Abnormalities That Influence Management (%)||LR+||LR–||Indications|
|Hemoglobin||0.1||3.3||0.90||Anticipated major blood loss or symptoms of anemia|
|White blood cell count||0.0||0.0||1.00||Symptoms suggest infection, myeloproliferative disorder, or myelotoxic medications|
|Platelet count||0.0||0.0||1.00||History of bleeding diathesis, myeloproliferative disorder, or myelotoxic medications|
|Prothrombin time (PT)||0.0||0.0||1.01||History of bleeding diathesis, chronic liver disease, malnutrition, recent or long-term antibiotic use|
|Partial thromboplastin time (PTT)||0.1||1.7||0.86||History of bleeding diathesis|
|Electrolytes||1.8||4.3||0.80||Known renal insufficiency, congestive heart failure, medications that affect electrolytes|
|Renal function||2.6||3.3||0.81||Age > 50 years, hypertension, cardiac disease, major surgery, medications that may affect renal function|
|Glucose||0.5||1.6||0.85||Obesity or known diabetes|
|Liver function tests||0.1||No indication. Consider albumin measurement for major surgery or chronic illness|
|Electrocardiogram||2.6||1.6||0.96||Men > 40 years, women > 50 years, known coronary artery disease, diabetes, or hypertension|
|Chest radiograph||3.0||2.5||0.72||Age > 50 years, known cardiac or pulmonary disease, symptoms or exam suggest cardiac or pulmonary disease|
*LR+ is positive likelihood ratio, LR– is negative likelihood ratio.
Reprinted with permission from Elsevier Health (USA). In: Smetana GW, Macpherson DS. The case against routine preoperative laboratory testing. Med Clin North Am. 2003;87:7-40.