A Guide to Preoperative Assessment

Abstract

As part of their training, Associates-in-Training (AiTs) will spend time in hospital within surgical specialties. Most hospitals have dedicated clinics for the preoperative assessment of patients scheduled for elective surgery, which are usually run by specialist nurses. However, sometimes, the responsibility for preoperative assessment will fall to the AiT. If you have not done this before, it can be daunting and it may be difficult to know which investigations patients need. Most hospitals will have preoperative assessment guidelines and proformas for you to use but here are some basics to get you started.

What is preoperative assessment?

Preoperative assessment is important and serves two main purposes:

Firstly, to provide patients with information about their surgical procedure, anaesthetic and recovery

Secondly, to ensure that the patient is fit for surgery

What is my role?

The patients you see should already have been seen by a surgeon so that they will know about the operation they are having. Patients will also be seen by an anaesthetist to discuss their anaesthetic, but this often only happens on the day of surgery. If you can ensure all the necessary investigations are done and potential problems flagged up beforehand this will be very helpful.

What should I do?

Take a thorough history and examination including an anaesthetic history. Particularly important points to cover include:

A personal or family history of anaesthetic problems—these range from post-operative nausea and vomiting to rare but life-threatening complications like malignant hyperthermia and suxamethonium apnoea

Medication history—some medications (e.g. steroids, anti-platelets and warfarin) may need to be stopped or require additional management in the perioperative period (see Box 1). It is especially important to ask about allergies as patients often receive a dose of prophylactic antibiotics once they are anaesthetized

Clinical examination will vary depending on your patient but should include examination of the cardiovascular and respiratory systems as a minimum

How do I decide which investigations patients need?

It can be challenging to decide which investigations a patient requires. Often, a judgement must be made on a case-by-case basis. However, the process can be facilitated by guidelines that have been published by the National Institute for Health and Clinical Excellence (NICE, 2003). These consider the appropriateness of investigations for particular patient groups and hence help you decide which investigations may be required (Table 1). In general, patients having major surgery and those with chronic health conditions require more preoperative investigations than patients having minor surgery who are otherwise well. Tables 2 and 3 provide a guide to classifying the severity of surgery and disease respectively.

Table 1.

Summary of guidance on the use of preoperative tests in elective surgery

	Electrocardiogram (ECG)	Chest x-ray	Full blood count	Renal function tests
Type of surgery	All patients undergoing cardiac surgery	All patients undergoing cardiac surgery	All patients undergoing cardiac surgery	All patients undergoing cardiac surgery or neurosurgery
Age and surgical severity	Any patient over 80 years		Any surgery with a severity grade of 3 or more	Any surgery with a severity grade 4 Patients over 60 years undergoing surgery with severity of grade 3 or more
	Patients over 60 years undergoing surgery with a severity grade of 3 or more		Patients over 60 years undergoing surgery with a severity of grade 2 or more
Cardiovascular disease	If ASA grade 2 or 3		If ASA grade 2 or 3 and surgical severity of grade 3 or more	If ASA grade 2 and surgical severity grade 3 (grade 2 if over 60 years)
				All patients with ASA grade 3 disease
Respiratory disease	If ASA grade 2, over 60 years and surgical severity grade 4 (grade 3 if over 80 years)	If ASA grade 3, over 60 years old and surgical severity grade 4	If ASA grade 2 or 3 and surgical severity of grade 3 or more (grade 2 if ASA grade 3 and over 80 years)	If ASA grade 2 disease and surgical severity grade 4 (grade 3 if over 60 years)
	If ASA grade 3, over 40 years and surgical severity grade 4 (grade 2 if over 60 years)			If ASA grade 3 and surgical severity grade 3 or more
Renal disease	If ASA grade 2, over 60 years and surgical severity grade 2 or more		If ASA grade 2 and surgical severity grade 2 or more All patients with ASA grade 3 disease	All patients with ASA grade 2 or 3 disease
	If ASA grade 3, over 40 years and surgical severity grade 4 (grade 2 if over 60 years)

Source: NICE (2003). See also Tables 2 and 3, for surgical severity and disease severity grading systems, including American Society of Anesthesiologists (ASA) scores.

Table 2.

Surgical severity

Grade	Examples
1	Diagnostic endoscopy or laparoscopy, breast biopsy
2	Inguinal hernia, varicose veins, adenotonsillectomy, knee arthroscopy
3	Total abdominal hysterectomy, transurethral resection of the prostate (TURP), lumbar discectomy, thyroidectomy
4	Total joint replacement, artery reconstruction, colonic resection, radical neck dissection

Source: NICE. Preoperative tests (2003).

Table 3.

Disease severity

	Mild systemic disease (ASA 2)	Severe systemic disease (ASA 3)
Cardiovascular
Hypertension	Good control using only one antihypertensive	Poor control, using more than one antihypertensive
Heart failure	Normal activities only slightly limited	Very limited activity
Angina pectoris/heart failure	Rarely needs to use glyceryl trinitrate (GTN) spray	Requires GTN spray on regular basis and/or unstable angina
Myocardial infarction	Over 1 month ago	Within the past month
Diabetes	Good control with no complications	Poor control, complications present
Respiratory
COPD	Wheeze well controlled by inhalers and occasional infective exacerbations	Breathless on slightest activity, usually wheezy, multiple infective exacerbations
Asthma	Good control with medication and no limit to activities	Poor control and limits activities.
		Requiring high dose of inhaler/oral steroids, frequent exacerbations requiring hospital admission
Renal
	Creatinine over 100 μmol/l but less than 200 μmol/l	Creatinine greater than 200 μmol/l requiring regular peritoneal or haemodialysis

Source: NICE. Preoperative tests (2003).

Other tests to consider include:

A pregnancy test, which should be carried out on any woman who says that she may be pregnant

A sickle cell test, which should be offered if there is a family history of the disease or the patient is from a high-risk area

• Haemostasis tests, which should be carried out if there is a specific indication (e.g. the patient is taking an anticoagulant or undergoing a procedure in which haemostasis is particularly important)

Urine analysis, random blood glucose and lung function tests may also be appropriate in some situations; the NICE guidance provides more detail in this regard

Box 1.

Preoperative medication management*

Patients will be taking these drugs for a reason and the risks and benefits of stopping any drug needs to be considered carefully. The decision of when to restart drugs will be made as soon as possible after surgery.

Aspirin, clopidogrel and dipyridamole: these drugs prevent normal platelet function. They need to be stopped for 7 days prior to surgery to allow time for new normally functioning platelets to be produced.

Warfarin: this inhibits clotting factor formation with effects lasting approximately 48 hours. It is essential to find out why the patient has been prescribed warfarin as it may not be safe to simply stop it, e.g. in the case of prosthetic heart valves or recurrent pulmonary embolus. A period of overlap with heparin via infusion or subcutaneous injection may be required. Senior help must be sought. As a general rule, if warfarin is not for a prosthetic heart valve, or an indication that puts the patient at high risk of thromboembolism, it should be stopped for 48 hours and the International normalized ratio (INR) should be less than 1.5 before surgery can be undertaken.

Combined oral contraceptive pill (COCP): this can increase the risk of venous thromboembolism in the perioperative period and may need to be discontinued. This decision should be made after assessment and discussion with the patient. The discussion should involve explaining the risks and benefits, eliciting any other risk factors such as personal or family history of thromboembolic disease and providing information about other forms of contraception that could be used in the interim. If it is decided to stop the COCP, it should ideally be stopped 4 weeks before major elective surgery, any surgery to the legs or surgery that will cause prolonged immobilization of a lower limb. The British National Formulary (BNF) contains helpful guidance on this topic.

Oral hypoglycaemics and insulin: these increase the risk of perioperative hypoglycaemia due to fasting. To avoid this, diabetic patients should be first on operating lists and regular blood glucose monitoring is essential.

For minor surgery, normal insulin and oral hypoglycaemics should be omitted on the day of surgery and restarted with the first meal post-operatively

For major surgery, normal insulin and oral hypoglycaemics should be omitted on the day of surgery and an insulin sliding scale should be commenced preoperatively. This should continue until the patient is eating and drinking satisfactorily. Oral hypoglycaemics can then be recommenced, but long-acting insulin may need to be converted to short acting for a period of time to avoid hypoglycaemia.

Poorly controlled diabetics may need to be admitted the night before surgery for an insulin sliding scale to ensure optimum control preoperatively. The hospital diabetic team will be able to provide further advice if needed.

Steroids: find out why the patient takes these, how long they have done so and whether their dose is static or fluctuates. This is important because long-term steroids suppress the hypothalamic-pituitary axis, leading to possible Addisonian crisis in the perioperative period due to the surgical stress response. This can be avoided by giving an extra dose of steroid prior to induction of anaesthesia and a reducing dose for the recovery period. Requirements for steroid cover will vary according to the severity of surgery.

As a general rule, patients taking less than 10 mg of prednisolone a day do not need extra steroid cover but should continue their usual dose. This may need to be converted to an intravenous preparation, usually hydrocortisone, if the patient is nil by mouth. The BNF contains a useful conversion table.

Patients taking more than 10 mg daily for more than 3 weeks or who have taken such a dose within the past 3 months will need additional steroid cover. This is administered intravenously on induction of anaesthesia and then prescribed as a reducing dose for the post-operative period. The amount required will depend upon the severity of surgery and will be decided by the anaesthetist and surgeon.

Angiotensin-converting enzyme (ACE) inhibitors: avoid on the morning of surgery as these drugs can cause profound hypotension perioperatively.

These are guidelines only. Please refer to local policy.

If a patient is anaemic

Anaemia is usually investigated and treated before elective surgery, ideally guided by haematinics and avoiding blood transfusion. However, if surgery is needed more urgently, then the team may need to proceed before the anaemia is corrected.

What about other investigations?

If you are concerned about a patient's co-morbidities or are not sure if further preoperative investigations (e.g. echocardiography or pulmonary function tests) are needed, you should contact the anaesthetist who will be responsible for the patient or the on-call anaesthetist. Your hospital's anaesthetic secretaries should be able to help you do this.

Patients to flag up prior to the date of surgery

If a patient has any of the following conditions, it is advisable to discuss them with the anaesthetist as they have an increased likelihood of problems during anaesthesia. The anaesthetic may need to be adapted to reduce this risk.

Severe cardiovascular, respiratory or renal disease (see Table 3)

Severe allergies/anaphylaxis (especially to latex)

Personal or family history of anaesthetic problems (such as malignant hyperthermia, suxamethonium apnoea or difficult airway)

Obesity: patients with a body mass index (BMI) greater than 30 have an increased risk of obstructive sleep apnoea, gastro-oesophageal reflux disease and other co-morbidities, such as diabetes. Special equipment may need to be available for their admission, including special theatre tables, correctly sized blood pressure cuffs and extra staff for safe manual handling

Diabetes: patients with diabetes may have co-existing microvascular and macrovascular disease which could increase their risk of a cardiovascular event in the perioperative phase. Chronic renal impairment may also be present, leading to problems with fluid balance and drug excretion. In addition, particular consideration needs to be given to their medication requirements in the perioperative period (see Box 1)

Previously undiagnosed heart murmurs

Severe gastro-oesophageal reflux disease: this increases the risk of aspiration at induction of anaesthesia, requiring the use of a different technique to avoid this possibility

What are the fasting guidelines?

These apply for both regional and general anaesthetics as there is always a small possibility that sedation or general anaesthesia may be required during a planned regional anaesthetic. According to guidelines from the Royal College of Nursing, patients can have

Water or clear fluids up to 2 hours before surgery

Food (which includes solids, milk and milk-containing drinks) up to 6 hours before surgery

Normal medications on the morning of surgery (see Box 1)

Local protocols should be available to help you with this, but if not, then consult senior colleagues.

In the GP surgery

When referring a patient for surgery, it is worth considering whether measures are necessary to help improve their health and hence fitness for the operation. This may include referral to services such as the smoking cessation clinic or weight loss programmes. It also includes provision of optimal treatment for chronic conditions, such as diabetes and chronic respiratory disease. Such measures will help reduce the risk of perioperative complications and facilitate a rapid recovery.

How can I get more experience?

Try to get to theatre to see as many different procedures as possible. This will give you an idea of what is involved, the type of anaesthetic and the length of time taken. If you are interested, most hospitals have high-risk preoperative assessment clinics usually run by anaesthetists. These can include specialist investigations such as cardiopulmonary exercise testing which you could arrange to attend. A friendly anaesthetist could also show you some of the more basic assessments such as ways to assess the airway.

The ‘Enhanced Recovery Programme’

The ‘Enhanced Recovery Programme’ is a package which aims to improve patient comfort, facilitate rapid recovery and reduce length of stay following all major elective surgery. Originally developed in Denmark for patients undergoing colorectal surgery, its use is becoming increasingly widespread throughout the UK. The key elements are

Preoperatively, there is an emphasis on obtaining optimal management of a patient's chronic health conditions. Prior to surgery, attention is paid to nutrition, with high calorie drinks taken at specified intervals up to 2 hours before surgery

Perioperatively, standardized anaesthetic and surgical techniques are employed, ensuring adequate pain control and avoidance of post-operative nausea and vomiting

Post-operatively, early oral nutrition and mobilization are crucial

In order for the programme to be most effective, it requires a well-trained highly motivated multidisciplinary team and a well-informed highly motivated patient. Patients are therefore carefully selected preoperatively.

References

American Society of Anesthesiologists. ASA physical status classification system. Accessed via www.asahq.org/clinical/physicalstatus.htm [date last accessed 08.02.2011].

Association of Anaesthetists of Great Britain and Ireland. Pre-operative assessment and patient preparation. The role of the anaesthetist (2010) Accessed via www.aagbi.org/publications/guidelines/docs/preop_2010.pdf [date last accessed 08.02.2011].

British National Formulary. Pharmaceutical Press. Accessed via bnf.org [date last accessed 28.03.2011].

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McGill

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Cryer

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Perioperative management of surgical patients with diabetes mellitus. Anesthesiology (1991) 74: p. 346–59.

NHS Institute for Innovation and Improvement. Enhanced Recovery Programme (2008) Accessed via www.institute.nhs.uk/quality_and_service_improvement_tools/quality_and_service_improvement_tools/enhanced_recovery_programme.html [date last accessed 13.2.2011].

NICE. Preoperative tests. The use of routine preoperative tests for elective surgery (2003) Accessed via www.nice.org.uk/nicemedia/live/10920/29090/29090.pdf [date last accessed 08.02.2011].

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