Pre-operative assessment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Mohammed A. Sbeih, M.D.[2] Phone:617-849-2629

Overview

The goal of medical preoperative clearance is to assess medical problems in the patients to identify unrecognized co-morbid diseases and optimize preoperative medical condition, also the preoperative medical assessment helps the doctors to decide if the patient is suitable for the proposed surgery according to the patient's risk category, and identify the factors that may reduce the patient risk and provide recommendations for post-operative care. Preoperative clearance usually starts by identifying the type of surgery to be performed and the risk category of the patient who need this surgery.

Perioperative risk of death

Patients can be divided into different risk categories based on the basis of their preoperative medical assessment. this helps the doctors to decide if the patient is suitable for the proposed surgery or procedure, and identify the factors that may reduce the patient risk. There are many factors that may influence the patient risk of complications, including death.

• Anesthesia

Although the modern anesthesia is safe the risk varies according to the type of Anesthesia (general or regional anesthesia).

Patient and surgical factors are more important risk predictors.

The American society of anesthesiologists (ASA) Classification is a predictor of preoperative mortality. It also predicts cardiac and pulmonary morbidity.

ASA classification

Class	Systemic disturbance	Mortality
1	Healthy patient with no disease outside of the surgical process	<0.03%
2	Mild-to-moderate systemic disease caused by the surgical condition or by other pathologic processes	0.2%
3	Severe disease process which limits activity but is not incapacitating	1.2%
4	Severe incapacitating disease process that is a constant threat to life	8%
5	Moribund patient not expected to survive 24 hours with or without an operation	34%
E	Suffix to indicate an emergency surgery for any class	Increased

• Type of procedure or surgery

Perioperative risk of complications varies according to the type of surgery.

• Patient age

Some studies showed that the risk of surgery increases with advancing age.

• Emergency procedure

In emergency procedures the risk of complications may increases two to four times, or even more than that in elderly patients.

• Pulmonary factors

There are several pulmonary factors that may increase the risk of surgical patients, these may include:

• Cigarete smoking.
• Respiratory diseases.
• Abnormal chest x-ray or phisical examination findings.
• Thoracic or upper abdominal surgery.
• Morbid obesity.
• Age over 60.

• Cardiac factors

There are several cardiac factors that may increase the risk of surgical patients, these may include:

• History of prosthetic valves.
• History of rheumatic fever.
• Congestive heart failure.
• Arrhithmia.

Preoperative clinical evaluation

In general, the overall risk of surgery is extremely low in healthy individuals.

History

• The patient should be asked about his age.Some studies found a small increased risk of surgery associated with advancing age. Mortality risk increased linearly with age :for most surgical procedures due to increasing numbers of comorbidities with advancing age.

• The patient should be asked if he had a history of:

• Heart diseases,irregular heart beat, murmurs or rheumatic fever as a child.
• Pulmonary diseases such as asthma, bronchitis, or emphysema.
• Chest pain, angina, or chest tightness.
• Hypertension or hypotension.
• Shortness of breath, cough.
• Liver diseases, jaundice or hepatitis.
• Gastrointestinal problems or indigestion.
• Diabetes.
• Thyroid problems.
• Kidney problems.
• Weakness or numbness in the arms or legs.
• Seizures or blackouts.
• Bleeding disorders.
• Blood clot abnormality.
• Arthritis or joint pain.

• The patient should be asked if he/she:

• Have any allergies for food or medication.
• Have a list of any medications he is currently taking, including over-the-counter medications. Nonsteroidal anti-inflammatory drugs are associated with an increased risk :of perioperative bleeding.
• Had any other medical conditions in the past.
• Had any previous surgeries or anesthesia.
• May be pregnant.
• Have taken steroid medications before.
• Had any problem with a previous anesthetic.

• The patient should be asked when did he last eat or drink at the day of surgery.
• The patient should be asked about his Height and Weight. Studies showed that obesity is not a risk factor for most adverse postoperative outcomes, with the exception of :deep venous thrombosis and pulmonary embolism. However, some cardiac surgery studies have shown higher complication rates for obese patients, such as increased hospital :stay, wound infections and prolonged mechanical ventilation.
• The patient should be asked about his exercise capacity, patients with unlimited exercise tolerance, who can walk two blocks on level ground without symptoms, generally :have low risk of postoperative complications.
• The patient should be asked when did he last eat or drink at the day of surgery.
• The patient should be asked if he smokes cigarettes, How many packs per day and for How many years.
• The patient should be asked if he drinks alcohol.There is increased risk for postoperative complications in Patients who misuse alcohol on a regular basis.

Preoperative laboratory testing

The American Society of Anesthesiologists recommends against routine preoperative laboratory testing in the absence of clinical indications. In specific circumstances, such as in patients with known underlying diseases or risk factors that would increase risk of surgical complications, and specific high risk surgical procedures, selective testing may be appropriate. If there is no significant change in clinical status, it may be safe to use test results that were performed within the past four months. These tests include:

1. Complete blood count (CBC)

Anemia maybe presents in asymptomatic patients and it is common following major surgery. Postoperative mortality maybe predicted by the preoperative hemoglobin level. CBC test should be done for:

• Patients 65 years of age or older.
• Patients who are undergoing major surgery.
• Young patients who undergoing major surgery with the expectation to result in significant blood loss.
• Patients with a history that suggests anemia.

2. Renal function test (RFT)

Serum creatinine concentration should be ordered for patients over the age of 50 undergoing intermediate or high risk surgeries, also if hypotension is likely, or when nephrotoxic medications will be used. Mild to moderate renal impairment is usually asymptomatic. Dosage adjustment of some medications may be needed if the patient has renal insufficiency.

3. Electrolytes

It is not recommended to be done routinely if the patient does not have a history of electrolytes abnormality.

4. Blood glucose

Diabetes increases the operative risk in patients undergoing vascular surgery or coronary artery bypass grafting. Routine measurement of blood glucose is not recommended for healthy patients before the surgery, since some studies showed that unexpected abnormal blood glucose results do not often influence perioperative management.

5. Liver function tests (LFT)

It is not recommended to do this test routinely unless the patient has a history of liver disease.

6. Hemostasis tests

It is not recommended do prothrombin time (PT) or Partial thromboplastin time (PTT) routinely unless the patient has bleeding disorder or an unusual bleeding tendency. Some doctors have suggested to test all patients who undergoing intermediate to high risk surgeries. This avoids the chance that clinicians may forget to ask about the bleeding history.

7. Urinalysis

It is usually done to detect any urinary tract infection which has the potential to cause wound infection after the surgery, especially with prosthetic surgery. If the test is positive, the patient should be treated with antibiotics and proceed with surgery without delay. Some studies showed that there is no reduction in the risk of postoperative wound infection if the patient treated with antibiotics before the surgery, and so, it is not indicated to test for Urinary tract infection before the surgery for every patient.

8. Pregnancy testing

Pregnant women may need specific perioperative management, this includes anesthetic teqniques. An elective surgery may be cancelled or postponed in pregnant women. The American society of anesthesiologists recommends that clinicians consider pregnancy testing for all woman of childbearing age . Many institutions require pregnancy testing for all reproductive age women before surgery.

9. Electrocardiogram (EKG)

This should be done to detect any recent myocardial infarction (MI) which known to be associated with high surgical morbidity and mortality, also it may be important as a baseline to be compared with the one postoperatively. In general, EKG alone may be a poor indicator of postoperative cardiac complications. The 2007 American College of Cardiology/American Heart Association (ACC/AHA) Guidelines on perioperative cardiovascular evaluation state that ECG is not useful in asymptomatic patients undergoing low risk procedures . Also, the European Society of Cardiology 2009 preoperative guidelines do not recommend ECG in patients without risk factors . According to the 2007 ACC/AHA guidelines the 12-lead ECG are recommended for the following patients:

• Patients who are scheduled to undergo vascular surgery and have at least one of the following clinical risk factors:

• Ischemic heart disease.
• Compensated or prior heart failure.
• Cerebrovascular disease.
• Diabetes.
• Renal insufficiency.

It is less strongly recommended to perform an ECG for patients scheduled to undergo vascular surgery with no clinical risk factors.

• Patients who are scheduled to undergo intermediate-risk surgery with known cardiovascular disease, peripheral artery disease, or cerebrovascular disease.It is less strongly recommended to perform an ECG for patients scheduled to undergo intermediate-risk surgery with at least one clinical risk factor.

10. Chest radiograph (Chest x-ray)

Its not recommended to do this test routinely before the operations in healthy patients, many studies showed that an abnormal chest x-ray findings may occur frequently, especially in elderly persons . According to the American College of Physicians (ACP), if there is a suspicion of cardiopulmonary disease from the patient's history or physical examination, then this test should be done, also in those older than 50 years of age who are undergoing abdominal aortic aneurysm surgery or upper abdominal/thoracic surgery . The American Heart Association recommend preoperative chest x.ray for patients with severe obesity (BMI ≥40 kg/m2).

ACC / AHA recommendations for perioperative cardiac assessment

“

Class I Patients who have a need for emergency noncardiac surgery should proceed to the operating room and continue perioperative surveillance and postoperative risk :stratification and risk factor management. (Level of Evidence: C) Patients with active cardiac conditions* should be evaluated and treated per ACC/AHA guidelines and, if appropriate, consider proceeding to the operating room. (Level of Evidence: B) Patients undergoing low risk surgery are recommended to proceed to planned surgery.† (Level of Evidence: B) Patients with poor (less than 4 METs) or unknown functional capacity and no clinical risk factors should proceed with planned surgery.† (Level of Evidence: B) Class IIa It is probably recommended that patients with functional capacity greater than or equal to 4 METs without symptoms‡ proceed to planned surgery.§ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for vascular surgery consider testing if it will change management.¶ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for intermediate risk surgery proceed with planned surgery with heart rate control.¶ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 1 or 2 clinical risk factors who are scheduled for vascular or intermediate risk surgery proceed with planned surgery with heart rate control.¶ (Level of Evidence: B) Class IIb Noninvasive testing might be considered if it will change management for patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for intermediate risk surgery. (Level of Evidence: B) Noninvasive testing might be considered if it will change management for patients with poor (less than 4 METs) or unknown functional capacity and 1 or 2 clinical risk factors who are scheduled for vascular or intermediate risk surgery. (Level of Evidence: B) §Noninvasive testing may be considered before surgery in specific patients with risk factors if it will change management. Clinical risk factors include ischemic heart disease, compensated or prior heart failure, diabetes mellitus, renal insufficiency, and cerebrovascular disease. ¶Consider perioperative beta blockade (see Table 12) for populations in which this has been shown to reduce cardiac morbidity/mortality.

”

Stepwise approach to preoperative cardiac assessment

Cardiac risk stratification for noncardiac surgical procedures

High (Reported cardiac risk often greater than 5%)

• Emergent major operations, particularly in the elderly
• Aortic and other major vascular surgery
• Peripheral vascular surgery
• Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss

Intermediate (Reported cardiac risk generally less than 5%)

• Carotid endarterectomy
• Head and neck surgery
• Intraperitoneal and intrathoracic surgery
• Orthopedic surgery
• Prostate surgery

Low (Reported cardiac risk generally less than 1%)

• Endoscopic procedures
• Superficial procedure
• Cataract surgery
• Breast surgery

Estimated energy requirements for various activities

1 MET Can you take care of yourself? 4 METs Climb a flight of stairs or walk up a hill? Eat, dress, or use the toilet? Walk on level ground at 4 mph or 6.4 km per h? Walk indoors around the house? Run a short distance? Walk a block or two on level ground at 2 to 3 mph or 3.2 to 4.8 km per h? Do heavy work around the house like scrubbing floors or lifting or moving heavy furniture? Participate in moderate recreational activities like golf, bowling, dancing, doubles tennis, or throwing a baseball or football? 4 METs Do light work around the house like dusting or washing dishes? Greater than 10 METs Participate in strenuous sports like swimming, singles tennis, football, basketball, or skiing? MET indicates metabolic equivalent.Adapted from the Duke Activity Status Index and AHA Exercise Standards.

Sources

http://www.askdrwiki.com/mediawiki/index.php?title=Preoperative_Clearance

http://www.asahq.org/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2146059/

http://www.ccspublishing.com/journals3a/Preoperative_Medical_Evaluation.htm

http://circ.ahajournals.org/content/116/17/e418.full.pdf+html

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