Preoperative Assessment
Optimization for surgery, risk reduction, perioperative medication recommendations
Questions and Answers
- 1.
Breast milk should be discontinued for how long prior to surgery?
- A.
8 hours
- B.
6 hours
- C.
4 hours
- D.
2 hours
Correct Answer
C. 4 hoursExplanation
(Answer:C) According to the ASA Task Force on Preoperative fasting, breast milk should not be consumed within 4 hours of surgery. Interestingly, non-human milk is considered safe when consumed at least 6 hours prior to surgery.
American Society of Anesthesiologists Task Force on Preoperative Fasting, Anesthesiology 90:896-905, 199Rate this question:
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- 2.
A 57-year old male is in pre-surgical testing for an elective laparoscopic cholecystectomy. He has an otherwise unremarkable medical history, and he is scheduled at 1 PM on the day of surgery. Which of the following is against the ASA guidelines for preoperative fasting?
- A.
Drinking orange juice at 7 AM
- B.
Eating toast with apple juice at 7 AM
- C.
Coffee with cream at 10 AM
- D.
An omelette with pancakes at 5 AM.
- E.
None of the above
- F.
More than one of the above
Correct Answer
C. Coffee with cream at 10 AMExplanation
(Answer: C) The guidelines for presurgical fasting are as follows:
Within two hours of surgery: Absolutely nothing
> 2 hours prior to surgery: Clear liquids only-- this includes water, carbonated
beverages, sports drinks, coffee without cream, tea without cream, etc.
> 4 hours prior to surgery: Breast milk
> 6 hours prior to surgery: Light meal, infant formula, nonhuman milk. An example of a light meal is toast or yogurt.
> 8 hours prior to surgery: Any meal.
In this case, the coffee with cream was consumed 3 hours prior to surgery. While coffee by itself is a clear liquid and would be safe greather than two hours prior to surgery, the cream is not a clear liquid and should not be consumed within 6 hours of surgery.
American Society of Anesthesiologists Task Force on Preoperative Fasting, Anesthesiology 90:896-905, 1999Rate this question:
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- 3.
A 65-year-old man comes to pre-surgical testing for a left hip replacement. He tells you he had a coronary stent placed 6 months ago and takes aspirin and plavix daily, but he does not remember any more details. Which of the following is a correct statement about this situation?
- A.
It is safe to schedule the surgery now.
- B.
If the stent is drug eluting, the patient should wait 6 months to schedule the case
- C.
If the stent is bare-metal, the patient should wait 6 months to schedule the case
- D.
If the stent is drug-eluting, the patient should wait 3 months to schedule the case
- E.
If the stent is drug-eluting, the patient should wait 12 months to schedule the case
Correct Answer
B. If the stent is drug eluting, the patient should wait 6 months to schedule the caseExplanation
Patients who have had a cardiac catheterization--especially with a drug eluting stent (DES) require long-term antiplatelet therapy to prevent restenosis. Now, a hip replacement is an elective procedure with a high risk of bleeding, so if at all possible, the patient should discontinue his plavix prior to the case. The problem is, this increases the patient’s perioperative risk of MI due to stent thrombosis, which carries a high mortality rate.
Current guidelines are that a DES requires treatment with plavix for a minimum of 12 months before discontinuing it for an elective procedure. For bare-metal stents (BMS), guidelines are to wait at least one month. Since this patient’s stent was placed 6 months ago, he could safely discontinue the plavix with a BMS now and in 6 months with a DES.
Chassot PG, Perioperative antiplatelet therapy: The case for continuing therapy in patients at risk of myocardial infarction. British Journal of Anesthesia, 2007; 99:316-3Rate this question:
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- 4.
A 68-year-old man comes to pre-surgical testing for a cataract repair. He has a past medical history significant for type II Diabetes, hypertension, and hyperlipidemia. He tells you that he has smoked a pack of cigarettes a day for the past 30 years. He also says that he develops shortness of breath when he walks up stairs and gets chest pain when he exercises. The last time this happened was two weeks ago when he worked out with his friend in the garage. His EKG is normal sinus rhythm with a rate of 72 and significant for a left axis deviation and left ventricular hypertrophy. Which of the following is the best next step in managing this patient?
- A.
Proceed with the surgery without further testing
- B.
Order an echocardiogram
- C.
Order an exercise stress test
- D.
Order a nuclear stress test
- E.
None of the above
Correct Answer
A. Proceed with the surgery without further testingExplanation
A cataract repair is a low-risk surgery. According to the American Heart Association (AHA) 2007 Guidelines, patients having low-risk surgery who do not have an active cardiac condition can proceed to surgery without further testing. The following are active cardiac conditions according to those guidelines: 1. Angina at rest or with minimal exertion 2. Decompensated CHF 3. Significant arrhythmia such as a symptomatic bradycardia, symptomatic ventricular arrhythmia, Mobitz II atrioventricular block, and third-degree atrioventricular heart block. 4. Severe valvular disease such as symptomatic aortic stenosis or mitral stenosis. ACC/AHA 2007 Guidelines for Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery. See: http://circ.ahajournals.org/content/116/17/e418.fullRate this question:
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- 5.
According current guidelines, which of the following patients should have her breast lumpectomy deferred for further cardiac work-up?
- A.
A 68 yo who cannot walk up stairs without getting short of breath
- B.
A 72 yo with CHF that experiences shortness of breath when he exercises
- C.
A 66 yo who is a lifelong smoker, has type II diabetes with uncontrolled blood sugar, and has a blood pressure of 155 / 91
- D.
A 64 year old with a Mobitz type II rhythm at 64 without ST elevation or T wave changes on her EKG
- E.
E. None of the above
Correct Answer
D. A 64 year old with a Mobitz type II rhythm at 64 without ST elevation or T wave changes on her EKGExplanation
Most breast surgeries are considered low-risk. According to the American Heart Association (AHA) 2007 Guidelines, patients having low-risk surgery who do not have an active cardiac condition can proceed to surgery without further testing. The following are active cardiac conditions according to those guidelines: 1. Angina at rest or with minimal exertion 2. Decompensated CHF 3. Significant arrhythmia such as a symptomatic bradycardia, symptomatic ventricular arrhythmia, Mobitz II atrioventricular block, and third-degree atrioventricular heart block. 4. Severe valvular disease such as symptomatic aortic stenosis or mitral stenosis. ACC/AHA 2007 Guidelines for Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery. See: http://circ.ahajournals.org/content/116/17/e418.fullRate this question:
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- 6.
Of the following, which surgery has the highest risk of an adverse cardiac event?
- A.
Carotid endarterectomy
- B.
Left hip replacement
- C.
Hemicolectomy
- D.
Left femoral-popliteal bypass
- E.
Cholecystectomy
Correct Answer
D. Left femoral-popliteal bypassExplanation
The AHA has stratified non-cardiac surgeries into low, medium, and high risk of perioperative cardiac events. Low risk surgeries include endoscopic procedures, cataract repairs, and breast surgeries. These have a reported cardiac risk of < 1%, and according to some studies are lower risk than the patient’s baseline-- rendering the procedure day itself the safest time for the patient during the 30 day observation period.
Intermediate risk surgeries have a reported cardiac risk of 1-5%, and these include carotid endarterectomy (choice A), orthopedic surgeries (choice B), intrathoracic surgery, prostate surgery, and intraperitoneal surgery (choice C).
High risk surgery has a greater than 5% risk of cardiac event and includes aortic or other major vascular cases as well as peripheral vascular surgery-- such as a femoral-popliteal bypass (choice D).
ACC/AHA 2007 Guidelines for Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery. Available at: http://circ.ahajournals.org/content/116/17/e418.fullRate this question:
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- 7.
A 65 yo F with type II DM, CHF, and hyperlipidemia is planning to have an abdominal aneurysm repair. Which of the following medications should she continue on the morning of the surgery?
- A.
Fluvastatin
- B.
Metformin
- C.
Enalapril
- D.
Lasix
- E.
Glipizide
Correct Answer
A. FluvastatinExplanation
There is strong evidence that statins reduce perioperative cardiac risk. The DECREAE-III trial of 2009 showed that patients receiving fluvastatin had a reduced incidence of perioperative MI as well as 30-day non-fatal MI, and 30-day cardiac death. It is thought that statins stabilize plaques and reduce vascular inflammation. In this case, the patient should be told to take her Fluvastatin with a small sip of water.
Schouten O, Boersma E, Hoeks SE, et al.; Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group. Fluvastatin and perioperative events in patients undergoing vascular surgery. N Engl J Med. 2009;361(10):980–989.Rate this question:
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- 8.
A 31 yo M with type II DM takes Lantus, metformin, and glipizide. Which of the medications should he take on the morning of surgery?
- A.
His normal dose of Lantus
- B.
½ his normal dose of Lantus
- C.
½ his normal dose of Lantus and his metformin
- D.
⅓ his normal dose of Lantus and his Glipizide
- E.
Metformin and Glipizide
Correct Answer
B. ½ his normal dose of LantusExplanation
According to the American Diabetes Association, patients should hold metformin the day before surgery as well as the day of the case. This is because metformin can contribute to lactic acidosis if the patient’s renal function is damaged intraoperatively. Patients should hold any other oral hypoglycemics only on the morning of surgery (Glipizide, pioglitazone, etc.) As this patient will be NPO for several hours before the case, taking his normal dose of Lantus will put him at risk for hypoglycemia. Current recommendations are for patients to take ½ to 1/3rd their normal amount of long-acting insulin and for the surgery to be early on the schedule if possible. Hourly blood glucose should be checked intraoperatively. See: http://clinical.diabetesjournals.org/content/19/2/92.fullRate this question:
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- 9.
How many risk factors for obstructive sleep apnea (OSA) are listed here? 1. Being male 2. BMI > 30 3. Feeling tired, fatigued, or sleepy during the daytime 4. Neck circumference > 40 cm 5. Being treated for HTN 6. Insomnia 7. Age > 40
- A.
3
- B.
4
- C.
5
- D.
6
- E.
7
Correct Answer
B. 4Explanation
The STOP-Bang screening questionnaire is an 8-question survey that categorizes a patient’s risk for OSA as high or low. The risk factors are as follows: 1. Loud snoring 2. Feeling tired during the daytime 3. Someone observing the patient stopped breathing during sleep 4. Being treated for HTN 5. BMI > 35 6. Age > 50 7. Neck circumference > 40 cm 8. Being male Four of these were listed above. See: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3325050/Rate this question:
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- 10.
According to the AHA, which of the following patients should have infectious endocarditis (IE) prophylaxis?
- A.
A 2 yo F who is teething for an emergent appendectomy
- B.
A 65 yo M with a history of a mechanical aortic valve placed in 1996 for the emergent draining of an oral abscess
- C.
A 67 yo M with a history of heart transplant in 2005 for a penile prosthesis insertion
- D.
A 46 yo F with history of endocarditis when she was a child for a total abdominal hysterectomy
- E.
More than one of the above
Correct Answer
B. A 65 yo M with a history of a mechanical aortic valve placed in 1996 for the emergent draining of an oral abscessExplanation
The AHA made several changes to IE prophylaxis guidelines in 2007 that dramatically narrowed the procedures and patients for which prophylaxis is recommended. This came from evidence indicating that prophylaxis only prevents a small number of cases of IE anyway. According to these guidelines, GU or GI tract cases do not need endocarditis prophylaxis (choices A and D). Surgeries that perforate the oral mucosa are still an indication. Risk factors warranting IE prohylaxis include: prosthetic valves, history of IE, congenital heart disease (with specific guidelines - see link below), and valvulopathy developing in a cardiac transplant patient. Choice B is the only procedure and high risk patient according to these guidelines. see link below: http://www.heart.org/HEARTORG/Conditions/CongenitalHeartDefects/TheImpactofCongenitalHeartDefects/Infective-Endocarditis_UCM_307108_Article.jspRate this question:
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- 11.
A 76 yo m with PMHx of ACS with 2 stents placed 5 years ago presents for an elective cholecystectomy. He is 6'2 and weighs 73 kg. His pre-procedure hematocrit is 35. According to current guidelines and assuming the patient remains hemodynamically stable, what is the maximal allowable blood loss for this procedure?
- A.
500 ml
- B.
750 ml
- C.
780 ml
- D.
850 ml
- E.
1.0 ml
- F.
None of the above
Correct Answer
C. 780 mlExplanation
The maximum allowable blood loss is a function of the patient's pre-procedure blood volume, hematocrit, and minimum allowable hematocrit. This patient has a history of myocardial infarction, so the minimum recommended hematocrit for him is 30. The first step toward this calculation is knowing the patient's pre-procedure blood volume. For a man, blood volume is approximately 75ml / kg. As this man weighs 73 kg, his blood volume is 73 x 75 = 5475. Now, the hematocrit is 35, and as this patient has a history of coronary artery disease, the minimum hct allowable for him is 30. The formula is [Hct(original) - Hct(minimal)] / Hct(original), so (35 - 30 ) / 35 = 0.143. This fraction x blood volume = 0.143 x 5473 = 0.782.
Miller RD and Pardo MC, Basics of Anesthesia 6th Edition, Elsevier Publishers, Philadelphia PA, 2011.Rate this question:
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- 12.
A 33 yo F with PMHx of Lupus presents for a myomectomy. Since she was 16, she has been taking 20mg prednisone to control the symptoms and has been unable to taper her dose. Which of the following is consistent with current practice guidelines regarding perioperative steroid replacement?
- A.
Hold steroids the night before this procedure
- B.
20mg prednisone on morning of procedure
- C.
100mg hydrocortisone on morning of procedure
- D.
Adrenal function testing prior to procedure with dosing deferred
Correct Answer
B. 20mg prednisone on morning of procedureExplanation
Current evidence suggests that patients taking longterm steroids should receive their normal dose on the day of surgery. A larger or "stress" dose is only indicated for patients with primary hypothalamus-pituitary-adrenal axis disease.
Also, adrenal function testing prior to surgery in patients taking longterm steroids has not been shown to reduce incidence of adrenal crisis.
http://archsurg.jamanetwork.com/article.aspx?articleid=402330Rate this question:
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- 13.
A 66 yo m with a PMHx of CAD with two drug eluting stents placed 14 months ago, HTN, HLD, stable angina, and controlled CHF presents for an AV fistula creation. According to current guidelines, which of the following medications should he discontinue prior to this procedure?
- A.
Aspirin
- B.
Clopidogrel
- C.
Atenolol
- D.
Simvastatin
- E.
Enalapril
- F.
Lantus
Correct Answer
B. ClopidogrelExplanation
Patients receiving drug eluting stents should defer elective surgery for at least 12 months as electron micrographs show significantly increased patency with time. Discontinuing plavix during this early period is associated with a significant risk of thrombus formation, myocardial infarction, and death. After 12 months though, for elective surgery, current guidelines are to discontinue plavix for at least 7 days. The other medications listed are thought to be benefitical perioperatively (especially beta blockers-- class I recommendation), so they should be continued on the morning of surgery.
Barash, PD and Cullen BF, Clinical Anesthesia, 6th Edition, Chapter 42: Anesthesia for Vascular Surgery, pg. 1111-2.Rate this question:
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- 14.
A 34 yo F with PMHx of hypothyroidism presents for a myomectomy. She is 5'5" and weights 100kg. She says she last ate at 8PM the previous evening and took her morning medication with a small sip of water. If the case starts at 8AM, approximately what is her fluid deficit?
- A.
1.2 L
- B.
1.5L
- C.
1.7L
- D.
> 2.0 L
Correct Answer
C. 1.7LExplanation
Pre-operative fluid deficit is a function of weight and the time that a patient was NPO. For maintenance, the first 10kg of a patient's weight should receive 4ml/hr, the second 10kg 2ml/hr, and every kg after that 1mg/hr. This patient weighs 100kg, so 40+20+80 = 140. She was NPO for 12 hours, so 140 x 12 = 1.68L.
Barash, Clinical Anesthesiology, 6th edition, Chapter 10: Cardiovascular Anatomy and Physiology, 2009.Rate this question:
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- 15.
According to the ASA 2011 Guidelines for Preanesthetic Evaluation, at what age should all patients get a screening EKG?
- A.
Age 40 for men and 50 for women
- B.
Age 50 for both men and women
- C.
Age 60 for men and 50 for women
- D.
Age 65 for both men and women
- E.
None of the above
Correct Answer
E. None of the aboveExplanation
While previous guidelines said that men over 40 and women over 50 should receive a screening EKG, the 2011 guidelines say that age alone is not an indication. Instead, the patient's comorbidities, the invasiveness of the surgery, and the history and physical should determine if the patient needs an EKG.
Practice Advisory for Preanesthesia Evaluation, American Society of Anesthesiologists, pg8, 2011.Rate this question:
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- 16.
A 25 yo m with no PMHx is referred by his primary doctor for resection of a right sided pheochromocytoma. Which of the following medications should this patient be taking prior to surgery?
- A.
Propranolol
- B.
Phenoxybenzamine
- C.
Labetalol
- D.
Magnesium Sulfate
- E.
Hydralazine
Correct Answer
B. PhenoxybenzamineExplanation
As a pheochromocytoma is an endogenous production and release of catecholamines, perioperative mortality from dramatic blood pressure swings and their consequences-- ACS, CHF, cerebral hemmorage, and arrhythmias--approaches 45% when untreated.
Preventing vasoconstriction with phenoxybenzamine (non-selective a-antagonist) has been shown to reduce mortality to 0-3%.
If a patient receives a b-blocker without alpha blockade, he may have experience alpha mediated vasoconstriction and have an extremely dangerous elevation in blood pressure.
Barash, Clinical Anesthesia, 6th Edition, Chapter 49: Endocrine Function, pg. 1295Rate this question:
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- 17.
A 56 yo F presents to pre-anesthesia testing for a vaginal hysterectomy. She is 155 cm and weighs 120kg. She has a PMHx of type II diabetes and hypertension that is controlled with medication. What is her ideal body weight?
- A.
45 kg
- B.
50kg
- C.
55kg
- D.
60kg
- E.
None of the above
Correct Answer
B. 50kgExplanation
Ideal body weight (IBW) is an idea made by insurance companies for the weight for each gender and height that has the lowest mortality. The formula is:
IBW (kg) = height (cm) - x, where x = 100 for adult males and 105 for adult females.
Barash, Clinical Anesthesia, 6th Edition, Chapter 47: Anesthesia and Obesity, pg. 1231, 2009.Rate this question:
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- 18.
A 71 yo M with PMHx of HTN, atrial fibrillation, and obesity presents for a carotid endarterectomy (CEA) after a screening ultrasound showed 75% stenosis on the left side. He takes aspirin, dipyridamole, and metoprolol. Which of these medications should he continue throughout the perioperative period?
- A.
Aspirin
- B.
Aspirin and plavix
- C.
Metoprolol
- D.
Aspirin, plavix, and metoprolol
Correct Answer
D. Aspirin, plavix, and metoprololExplanation
This patient has known peripheral vascular disease and needs his metoprolol for rate control; continuing his beta blocker is a Class I recommendation.
Also, the North American Symptomatic Carotid Endarterectomy Trial (NASCET), patients taking aspirin and plavix had a significantly lower stroke rate when compared to patients taking either drug alone or patients without any anticoagulation.
Barsh, Clinical Anesthesia, 6th Edition, Chapter 42: Anesthesia for Vascular Surgery, pg 1118, 2009.
http://www.nejm.org/doi/full/10.1056/NEJM199108153250701Rate this question:
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- 19.
A 32 yo F presents for an elective breast reduction. She says her mother had surgery 10 years ago and had some trouble "waking up." You decide to perform a dibucaine test. The patient has a dibucaine number of 81. What does this mean?
- A.
She is homozygous for a mutant butylcholinesterase gene
- B.
She is heterozygous for a mutant butyl cholinesterase gene
- C.
She has butycholinesterase genes that are within normal limits
- D.
None of the above
Correct Answer
C. She has butycholinesterase genes that are within normal limitsExplanation
Butylcholinesterase is the enzyme that breaks down succinylcholine, so patients who do not have this enzyme will experience significantly prolonged muscle block.
The local anesthetic dibucaine inhibits normal butyl cholinesterase, and the degree of the inhibition is called the "dibucaine number." So in a normal patient, dibucaine blocks 80% of enzyme activity, so the dibucaine number is 80. In a patient with a partial mutation, dibucaine blocks only 40-60% of activity, and in a homogenous mutation it blocks 20%.
Miller's Anesthesia, 7th Edition, Chapter 29: Pharmacology of Muscle Relaxants and their Antagonists, 2009.Rate this question:
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- 20.
A patient with a dibucaine number of 21 would experience which of the following?
- A.
Prolonged muscle weakness after a dose of succinylcholine
- B.
Normal duration of muscle weakness after a dose of succinylcholine
- C.
Prolonged muscle weakness after a dose of rocuronium
- D.
Normal duration of muscle weakness after a dose of rocuronium
- E.
None of the above
Correct Answer
A. Prolonged muscle weakness after a dose of succinylcholineExplanation
Butylcholinesterase is the enzyme that breaks down succinylcholine, so patients who do not have this enzyme will experience significantly prolonged muscle block after they receive succinylcholine.
The local anesthetic dibucaine inhibits normal butyl cholinesterase, and the degree of the inhibition is called the "dibucaine number." In a normal patient, dibucaine blocks 80% of enzyme activity, so the dibucaine number is 80. In a patient with a partial mutation, dibucaine blocks only 40-60% of activity, and in a homogenous mutation it blocks 20%.
This patient has a dibucaine number of 21, so this means that his ability to metabolize succinylcholine will be below normal. Therefore, he will have prolonged muscle block after receiving succinylcholine.
Miller's Anesthesia, 7th Edition, Chapter 29: Pharmacology of Muscle Relaxants and their Antagonists, 2009.Rate this question:
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- 21.
Which of the following procedures is associated with the highest rate of postoperative respiratory failure?
- A.
Carotid endarterectomy
- B.
Abdominal aortic aneurysm repair
- C.
Craniotomy
- D.
Mediastinoscopy
- E.
Femoral-popliteal bypass
Correct Answer
B. Abdominal aortic aneurysm repairExplanation
AAA repair is by far the procedure with the highest rate of postoperative respiratory failure -- even greater than thoracic procedures.
Miller's Anesthesia, 7th Edition, Chapter 35: Anesthetic Implications of Concurrent Disease, 2009.Rate this question:
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