How to Evaluate the Pre-Op Patient for the Physician Assistant Exam
The Physician Assistant Exam (PANCE) will ask questions about the pre-op patient. Suppose the surgical team has assessed the patient, and you decide that the patient needs to go to the operating room. This may be an emergent situation or an elective surgery, such as an elective laparoscopic cholecystectomy.
Well, in addition to the H&P you’ve already done, you need to order some baseline labs and also assess how risky it is to take this patient to the OR. In other words, will the patient likely survive the surgery?
Look at the labs
If the patient was initially seen in the emergency room, he or she may have already drawn most of the labs you need. The PANCE/PANRE may ask you which additional labs you need to confirm or deny a particular diagnosis. For example, if someone has abdominal pain radiating to the back, you may need to order an amylase and/or lipase in order to confirm that pancreatitis is present.
Here are some labs you may encounter on the test:
Complete blood count (CBC): The CBC is a common lab test — don’t leave home without it. An elevated white blood cell count can indicate either a stress response or an infection. If you see a left shift or bandemia, then an infection is likely present. Significantly elevated hemoglobin/hematocrit levels may mean significant volume depletion, especially in the setting of an individual who has recurrent nausea/vomiting and poor oral intake.
Anemia can point you in the direction of a chronic bleeding problem from the GI tract or a developing hematoma somewhere (if a trauma or fall occurred). Remember that the platelet count can be high in infections, inflammation, and iron deficiency, all of which can happen in a surgical patient.
Chemistry panel: A chemistry panel is useful. If the person is experiencing N/V/D, then knowing the serum sodium and potassium is important; the potassium may be low. If the person has a history of diabetes, you need the blood glucose level as well as the kidney function. Make sure you know the kidney function of anyone who’s going to undergo some type of imaging study that uses intravenous dye.
Levels: If the person is on a medication that requires some type of therapeutic monitoring, such as warfarin (Coumadin), theophylline (Theo-Dur), lithium (Eskalith), and/or digoxin (Lanoxin), then levels may need to be drawn. Volume depletion and kidney disease can really affect lithium and digoxin levels.
Any type of bowel process has the potential to dramatically affect the INR. If the person has an active GI bleed, the blood urea nitrogen (BUN) level can be really elevated as compared to the creatinine level. It’s generally recommended you obtain baseline coagulation studies (PT/INR and PTT) prior to any surgery.
Liver function tests (LFTs): Whether you obtain liver function tests should depend on the history as well as the clinical presentation. If someone presents with right upper-quadrant pain, obtaining LFTs is essential. If the person has icterus on examination, obtaining LFTs is important. If the surgery isn’t related to the abdomen and there is no history of liver disease or any significant past medical history, LFTs aren’t likely needed.
Which of the following can elevate the blood urea nitrogen (BUN) levels?
(A) Saline administration
(B) Bleeding due to diverticulosis
(E) Bleeding due to a duodenal ulcer
The correct answer is Choice (E), bleeding due to a duodenal ulcer. Saline administration would lower the BUN levels, because volume depletion can be a cause of an elevated BUN. A lower GI bleed would not cause an elevation in the BUN, so Choice (B) is wrong.
An upper GI bleed, especially a slow upper GI bleed, would. Malnutrition, Choice (C), would cause someone to have a low BUN level due to the low protein stores in the body. Tetracycline, not penicillin, increases BUN levels, so Choice (D) is incorrect.
Assess the perioperative risk
Be able to stratify your surgical patient’s risk of morbidity and mortality. The H&P is vital in identifying risk factors. Significant risk factors include coronary artery disease, diabetes, kidney disease, and active/ongoing cardiac issues. These include a recent myocardial infarction or history of congestive heart failure or valvular problems (examples being significant aortic stenosis or mitral regurgitation).
If a person has significant cardiac risk, the patient may need further testing and clearance from the cardiologist before being allowed to proceed with surgery.
Of course, the type of surgery is also important in determining the surgical risk. For example, the guidelines from the American College of Cardiology (ACC) stratify risk based on cardiac versus noncardiac surgery. Another important criterion often cited is the Goldman criteria for surgery, which evaluate cardiac risk in patients for noncardiac surgery.