Pre-operative Management
Iain G. Martin in Textbook of Surgery 3rd Edition, Blackwell Publishing.2006
Introduction
This chapter covers care of the patient from the time the patient is considered for surgery through to immediately prior to operation and deals with important generic issues relating to the care of all surgical patients. Whilst individual procedures each have unique aspects to them, a sound working understanding of the common foundation of the issues involved in pre-operative care is critical to good patient outcomes.
Informed consent
Although often thought of in a purely medicolegal way, the process of ensuring that a patient is informed about the procedure that they are about to undergo is a fundamental part of good quality patient care. Informed consent is far more than the act of placing a signature on a form; that signature in itself is only meaningful if the patient has been through a reasonable process that has left them in a position to make an informed decision.
There has been much written around issues of informed consent, and the medico-legal climate has changed substantially in the past decade. It is important for any doctor to have an understanding of what is currently understood by informed consent.
Although the legal systems in
Until relatively recently, the standard applied to deciding whether the patient was given adequate and appropriate information with which to make a decision was the so-called Bolam test, that is practitioners are not negligent if they act in accordance with practice accepted by a reasonable body of medical opinion.
Recent case law from both England and Australia and the standards embedded in the New Zealand's Health and Disability Commissions code of patient rights have seen a move away from the existing position. Although this area is complex, the general opinion is that a doctor has a duty to disclose to patients material risks. A risk is said to be material if 'in the circumstances of that particular case, a reasonable person in the patient's position, if warned of the risk would be likely to attach significance to it or the medical practitioner is, or should reasonably be aware that the particular patient, if warned of the risk would attach significance to it'. It is important that this standard relates to what a person in the patient's position would do and not just any reasonable person.
Important factors in considering the kinds of information to disclose to patients are:
· The nature of the potential risks: more common and more serious risks require disclosure.
· The nature of the proposed procedure: complex interventions require more information as do procedures when the patient has no illness.
· The patient's desire for information: patients who ask questions make known their desire for information and they should be told.
· The temperament and health of the patient: anxious patients and patients with health problems or other relevant circumstances that make a risk more important for them may need more information.
· The general surrounding circumstances: the information required for elective procedures might be different from that required in the emergency department.
What does this mean for a medical practitioner? Firstly, you must have an understanding of the legal framework and standards. Secondly, you must be able to document how appropriate information was given to patients - always write it down. On this point, whilst information booklets can be a very useful addition to the process of informed consent they do not remove the need to undertake open discussions with the patient.
Doctors often see the process of obtaining informed consent as difficult and complex, and this view is leant support by changing standards. However, the principles are relatively clear and not only benefit patients but their doctors as well. A fully informed patient is much more likely to adapt to the demands of a surgical intervention, and should a complication occur, they almost invariably accept such misfortune far more readily.
Pre-operative assessment
The appropriate assessment of patients prior to surgery to identify coexisting medical problems and to plan peri-operative care is of increasing importance. Modern trends towards the increasing use of day-of-surgery admission even for major procedures have increased the need for careful and systematic peri-operative assessment.
The goals of peri-operative assessment are:
• To identify important medical issues in order to
· optimise their treatment.
· inform the patient of the risks associated with surgery.
· ensure care is provided in an appropriate environment.
· To identify important social issues which may have a bearing on the planned procedure and the recovery period.
· To familiarise the patient with the planned procedure and the hospital processes.
Clearly the peri-operative evaluation should include a careful history and physical examination, together with structured questions related to the planned procedure. Simple questions related to exercise tolerance (such as can you climb a flight of stairs without shortness of breath) will often yield as much useful information as complex tests of cardiorespiratory reserve. The clinical evaluation will be coupled with a number of blood and radiological tests to complete the clinical evaluation. There is considerable debate as to the value of many of the routine tests performed, and each hospital will have its own protocol for such evaluations.
On the basis of the outcomes of this consultation a number of risk stratification systems have been proposed; the only one in widespread daily use is the relatively simple ASA (American Society of Anesthesiologists) system.
The pre-operative assessment and work-up will be guided by a combination of the nature of the operation proposed and the overall 'fitness' of the patient. Whilst there are a number of ways of looking at the type of surgery proposed, a simple three-way classification has much to commend it:
· Low risk: poses minimal physiological stress and risk to the patient, rarely requires blood transfusion, invasive monitoring or intensive care. Examples of such procedures would be groin hernia repair, cataract surgery, arthroscopy.
· Medium risk: moderate physiological stress (fluid shifts, cardiorespiratory effects) and risk. Usually associated with minimal blood loss. Potential for significant problems must be appreciated. Examples would be laparoscopic cholecystectomy, hysterectomy, hip replacement.
· High risk: significant peri-operative physiological stress. Often requires blood transfusion or infusion of large fluid volumes. Requires invasive monitoring and will often need intensive care. Examples would be aortic surgery, major gastrointestinal resections, thoracic surgery.
A low-risk patient (ASA I or II) will clearly require a far less intensive work-up than a high-risk patient (ASA III or IV) undergoing a high-risk operation.
Areas of specific relevance to peri-operative care are cardiac disease and respiratory disease. It is important that pre-existing cardiorespiratory disease is optimised prior to surgery to minimise the risk of complications. Patients with cardiac disease can be stratified using a number of systems (Goldman or Detsky indices) and this stratification can be used to guide work-up and interventions and provide a guide to prognosis. One of the most important respiratory factors is whether the patient is a smoker; there is now clear evidence that stopping smoking for at least 6 weeks prior to surgery significantly reduces the risk of complications.
Patient safety
Once in hospital, and particularly once under anaesthetic, patients rely upon the systems and policies of individuals and health care institutions to minimise the risk of inadvertent harm. Whilst every hospital will have slightly different policies the fundamental goals of these include:
• The correct patient gets the correct operation on the correct side or part of their body. An appropriate
method of patient identification and patient marking must be in place. It must be clear to all involved in the procedure, particularly for operations on paired limbs or organs, when the incorrect side could be operated upon.
· The patient is protected from harm whilst under anaesthetic. When under a general anaesthetic the patient is vulnerable to a number of risks. Important amongst these are pressure effects upon nerves, for example those on the common peroneal nerve as it winds around the head of the fibula.
· Previous medical problems and allergies are identified and acted upon.
Prophylaxis
Infection
Infections remain a major issue for all surgical procedures and the team caring for the patient needs to be aware of relevant risks and act to minimise such risks.
Before discussing the use of prophylactic antibiotics for the prevention of peri-operative infection, it is very important that issues of basic hygiene are discussed. Simple measures adopted by all those involved in patient care can make a real difference to reducing the risk of hospital-acquired infection. The very widespread and significant problems with antibiotic organisms such as methicillin-resistant Staphylo-coccus aureus (MRSA) have reinforced the need for such basic measures.
· Wash your hands in between seeing each and every patient.
· Wear gloves for removing/changing dressings.
· Ensure that the hospital environment is as clean as possible.
These measures, especially hand washing, should be embedded into the psyche of those involved in patient care.
In addition to the very important matters of hygiene and appropriate sterile practice, antibiotics should be used in certain circumstances to reduce the risk of peri-operative infection. Each hospital will have individual policies on which particular antibiotics to use in the prophylactic setting (see Chapter 7, p. 51). It is also important to state that whilst the use of prophylactic antibiotics can, when used appropriately, significantly reduce infectious complications, inappropriate or prolonged use can leave the patient susceptible to infection with antibiotic resistant organisms such as MRSA.
Both factors related to the patient and the planned procedure governs the appropriate use of antibiotics in the prophylactic setting.
Procedure-related factors
Table 1 indicates the risk of post-operative wound infections with and without the use of prophylactic antibiotics. In addition to considering the absolute risk of infection the potential consequences of infection must also be considered; for example, a patient undergoing a vascular graft (a clean procedure) must receive appropriate antibiotic cover because of the catastrophic consequences of graft infection.
Patient-related factors
Patients with immunosuppression and pre-existing implants and patients at risk for developing infective endocarditis must receive appropriate prophylaxis even when the procedure itself would not indicate their use.
Table 1. Risk of Post-Operative Wound Infection
| Type of Procedure | Type of Procedure | Wound Infection Rate (%) Prophylactic antibiotics | |
| No | Yes | ||
| Clean | No contamination gastrointestinal, genitourinary and respiratory tract not breached | 1-5 | 0-1 |
| Clean-Contaminated | Gastrointestinal or Respiratory track opened but without spillage | 10 | 1-2 |
| Contaminated | Acute inflammation, infected urine, bile, gross spillage from gastrointestinal tract | 20-30 | 10 |
| Dirty | Establish infection | 40-50 | 10 |
Venous thrombo-embolism
Deep vein thrombosis (DVT) is a not uncommon and potentially catastrophic complication of surgery. The risk for developing DVT ranges from a fraction of 1% to 30% or greater depending upon both patient- and procedure-related factors. Both patient-and procedure-related factors can be classified as low, medium or high risk (Table 2). High-risk patients undergoing high-risk operations will have a risk for DVT of up to 80% and a pulmonary embolism risk of 1-5% when prophylaxis is not used; these risks can be reduced by at least one order of magnitude with appropriate interventions.
Whilst a wide variety of agents have been trialled for the prevention of DVT, there are currently only three widely used methods:
· Graduated compression stockings: these stockings, which must be properly fitted, reduce venous pooling in the lower limbs and prevent venous stagnation.
· Heparin: this drug can be used in its conventional un-fractionated form or as one of the newer fractionated low-molecular-weight derivatives. The fractionated low-molecular-weight heparins offer the convenience of once-daily dosing for the majority of patients. It must however be remembered that the anticoagulant effect of the low-molecular-weight heparins cannot easily be reversed and, where such reversal may be important, standard unfractionated heparin should be used. • Mechanical calf compression devices: these machines work by intermittent pneumatic calf compression and thereby encourage venous return and reduce venous pooling. The three methods are complementary and are often used in combination, depending upon the patient and operative risk factors (Table 2).
The systematic use of such measures is very important if the optimal benefit is to be made for the potential reduction in DVT.
| Table 2. Prevention of deep vein thrombosis | ||||
| | Operative risk factors | |||
| Low (e.g. hernia repair) | Medium (e.g. general abdominal surgery) | High (e.g. pelvic cancer, orthopaedic surgery) | ||
| Patient risk factors | Low (age <40,> risk factors) | No prophylaxis | Heparin | Heparin and mechanical devices |
| | Medium (age >40, one risk factor) | Heparin | Heparin | Heparin and mechanical devices |
| | High (age >40, multiple risk factors) | Heparin and mechanical devices | Heparin And mechanical devices | Higher dose heparin, mechanical devices |
Pre-operative care of the acute surgical patient
A significant number of patients will present with acute conditions requiring surgical operations. Whilst the principles outlined above are still valid, a number of additional issues are raised.
Informed consent
Whilst there is still a clear need to ensure that patients are appropriately informed, there are fewer opportunities to discuss the options with the patient and their family. In addition, the disease process may have resulted in the patient being confused. The team caring for the patient needs to judge carefully the level of information required in this situation. Although it is very important that family members are kept informed, it has to be remembered that the team's primary duty is towards the patient. This sometimes puts the team in a difficult position when the views of the patient's family differ from that which the team caring for the patient hold. If such an occasion arises then careful discussion and documentation of the decision process is vital. Increasingly, patients of very advanced years are admitted acutely with a surgical problem in the setting of significant additional medical problems. It is with this group of patients that specific ethical issues around consent and appropriateness of surgery occur. It is important that as full as possible a picture of the patient's overall health and quality of life is obtained and that a full and frank discussion of the options, risks and benefits takes place.
Pre-operative resuscitation
It is important that wherever possible significant fluid deficits and electrolyte abnormalities are corrected prior to surgery. There is often a balance to be made between timely operative intervention and the degree of fluid resuscitation required. An early discussion between surgeon, anaesthetist and, when required, inten-sivist can help plan timing.
Pre-existing medical co-morbidities
There is clearly less time to address these issues and it may not be possible to address significant ongoing medical problems. Clearly such co-morbidities should be identified, and all involved with planning the operation should be informed. The issues are most acute for significant cardiac, respiratory, hepatic or renal disease.
Pre-operative nutrition
An awareness of the nutritional status of patients is important and such awareness should guide the decisions about nutritional support (see Chapter 5).
Before operation the malnourished patient should whenever possible be given appropriate nutritional support. There is no doubt that significant pre-operative malnutrition increases the risk of postoperative complications (> 10-15% weight loss). If possible such nutrition should be given enterally, reserving parenteral nutrition for the minority of patients in whom the gastrointestinal tract is not an option. Parenteral nutrition is associated with increased costs and complications and is of proven benefit in the seriously malnourished patient only, when it should be given for at least 10 days prior to surgery for any benefits to be seen. There is increasing evidence that enteral feeds specifically formulated to boost certain immune parameters offer clinical benefits for patients about to undergo major surgery.
After operation any patient who is unable to take in normal diet for 7 or more days should receive nutritional support, which as before operation should use the enteral route whenever possible.
Specific pre-operative issues
Stomas
A number of gastrointestinal operations will require the use of a temporary or permanent stoma (see Chapter 30). Prior to operation it is important that the patient is fully informed of the likelihood/possibility of a stoma. Clearly there will be operations that result in a stoma which could not be predicted being formed but such occasions should be very rare.
The concept of having an intestinal stoma is regarded by most patients as one of the most daunting aspects of facing surgery. Prior to surgery the patient should be seen by an experienced stoma/colorectal nurse to discuss in detail the nature of the stoma, the type of appliances likely to be used and the optimal site for its placement. The nurse specialist plays a very important role both in the immediate peri-operative period and beyond.
Diabetes mellitus
Diabetes mellitus is one of the most frequently seen medical co-morbidities which complicate peri-operative care. It is clearly important that patients with diabetes mellitus are appropriately worked up for surgery.
In the weeks leading up to elective surgery the management of the diabetes should be reviewed and blood glucose control optimised. Particular attention should be paid to cardiovascular and renal co-morbidities during the pre-operative assessment.
Generally patients with diabetes should be scheduled for surgery in the morning. For patients taking oral hypoglycaemic drugs, the drugs should be stopped the night before surgery and the blood glucose monitored. Patients with insulin-dependent diabetes should be commenced on an intravenous infusion regimen. There are two approaches to this:
· Variable-rate insulin infusion. The patients blood glucose levels are monitored regularly and the rate of insulin infusion adjusted. An infusion of dextrose is continued throughout the period of insulin infusion.
Single infusion of glucose insulin and potassium (GIK). Whilst this method has the advantage of simplicity it is not possible to adjust the rates of glucose and insulin infusion separately and the technique can lead to the administration of excessive amounts of free water. The variable-rate infusion is the most widespread approach and although more involved in terms of monitoring offers better glycaemic control; this in itself is associated with better patient outcomes.