THE PREOPERATIVE EVALUATION
The “preop” remains a common and important role for the medical consultant. The medical history is the same as any medical history and physical (H&P), but there are additional factors to consider.
What you need to know:
1. What is the surgical risk?
2. What are the patient’s risk factors?
3. How urgent is the surgery?
The AHA/ACC guidelines categorize surgical risk into low, intermediate, and high risk, with ambulatory surgery being low risk, and major vascular surgery being high risk. However, these guidelines do not list the hundreds of types of surgery in existence, and therefore one must use clinical judgment to estimate the surgical risk. Additionally, the AHA/ACC guidelines’ surgical risk categories refer to the risk of cardiovascular complications, not overall morbidity or mortality. Factors to take into consideration include:
- Duration of general anesthesia—surgery longer than 8 hours has been associated with increased risk of complications
- Emergency surgery—generally considered higher risk
- Blood loss
- Location and possible complications—e.g. abdominal surgery may be more risky in a patient with cirrhosis
Patient’s risk factors:
Cardiovascular risk is well described in the AHA/ACC guidelines. Consider also the risk of perioperative atrial fibrillation. A thorough medical history will help identify patients at risk for pulmonary complications, or have bleeding diatheses, or hypercoagulable states, or increased risk of delirium. The sections in this handbook that follow are useful guides for specific conditions. Recommended is to read “Cardiovascular Risk Stratification” and “Pulmonary Risk Assessment” for all patients, and other sections as pertinent.
Urgency of surgery:
Often underestimated, the urgency of surgery is a critical part of the preoperative evaluation. For example, a patient with significant cardiovascular risk might reasonably undergo stress testing for a major elective procedure, but would likely forego such testing prior to a necessary, urgent surgery for cancer. In the latter case, medical management may be preferred, as a positive preoperative stress test is unlikely to lead to coronary surgery or revascularization prior to the cancer surgery.
What you need to do:
Summarize your findings
Once these elements are known, the preoperative evaluation, including recommendations, should be summarized in a concise but thorough note.
First, state whether the patient is of acceptable risk to undergo surgery. As mentioned previously, avoid the term “clearance”—this term implies that nothing will go wrong. There may be complications with any surgical procedure—the key assessment is whether the anticipated benefits outweigh the risks.
“Mr. ____ presents for elective total hip arthroplasty. He is an acceptable candidate for this surgery.”
You may then go on and describe risks in more detail:
“He has increased cardiovascular risk due to clinical risk factors of diabetes and a prior TIA. However, his exercise tolerance is good and I do not recommend any further cardiac testing prior to this intermediate risk procedure.
He has increased risk of pulmonary complications due to the presence of COPD and obstructive sleep apnea. COPD remains stable, and his OSA is well treated with CPAP.
He is at risk for postoperative delirium.”
Patients are sent to the internist not just for an assessment, but for recommendations. Recommendations should go beyond the AHA/ACC guidelines. Our role as a medical consultant is also to provide guidance on perioperative medication management, management of chronic medical conditions, anticipate and mitigate potential perioperative complications, and recommend appropriate prophylactic measures.
“I recommend the following:
- Proceed with surgery without further cardiac testing.
- Continue his beta-blocker postoperatively. He is anticipated to be taking oral meds immediately postop, so he may be given metoprolol 50 mg PO BID, his home dose, holding if his SBP is <110 or HR <60, as often patients are relatively hypotensive initially postop.
- DVT prophylaxis should be provided postop per the 2008 ACCP guidelines, for hip replacement to include low molecular weight heparin, fondaparinux, or warfarin. Of these options, given our institutional formulary, I recommend dalteparin 5000 units subcutaneously once daily for at least 10 days.
- His postoperative pain should be treated, but psychoactive medications should be minimized to avoid delirium.
- Postoperative incentive spirometry.
- Continue his usual tiotropium inhaler postop, and have albuterol nebulizers PRN. Should he develop a COPD exacerbation, I would favor corticosteroids.
- Start a low dose supplemental correction algorithm with premeal lispro postop. Restart metformin when patient is eating and renal function has been confirmed to be acceptable.
- Follow up with his PCP 2-4 weeks postop.”
Communicate your evaluation
The patient should be informed of your recommendations. This note should be communicated to the surgeon, the primary care provider, and to any specialists as appropriate. The anesthesia team should have access to this note. State how you may be reached. Make sure you know who in your institution will be seeing the patient postop—it may be you, the surgery team alone, or an intensivist.
A few words on laboratory and ancillary testing:
There are many “standard” preoperative tests that do not need to be done routinely. In some cases, there is no consensus.
Not required unless personal or family history of bleeding diathesis
As a general rule, not necessary.
Pulmonary Function Tests (PFTs)
Obtain only if needed to diagnose previously unknown obstructive lung disease.
Arterial Blood Gas (ABG)
Obtain only if suspicion for CO2 retention that would affect postop management
*Clinical Risk Factors: Diabetes, Ischemic Heart Disease, History of Congestive Heart Failure, Cerebrovascular Disease, Chronic Kidney Disease
Many preoperative protocols, whether from anesthesia or the surgeon, require certain preoperative tests that the medical consultant may not feel are required. The ECG and coagulation tests are common examples of tests that are considered overused. Good communication between the medical consultant, patient, surgeon, and anesthesia team is essential—if the testing is required, we will often go ahead and order it so that the patient’s surgery will not be cancelled, but also take the situation as an opportunity to have a dialogue with those requesting the tests.
Updated May 2011