The optimization of the patient prior to surgery, where possible, provides the best opportunity for reduction of risks associated with anesthesia and surgery. Fit and young patients may have minimal need for preoperative intervention, but given that the median age of our populations in the western world are steadily increasing, the need for adequate assessment, preoperative medical optimization, and intraoperative monitoring will likely increase over coming years.

This chapter addresses preoperative medical assessment, anesthesia-specific concerns and intraoperative anesthetic monitoring systems, and the role of these aspects in optimization of the perioperative condition of the patient in the process of surgical risk reduction. It is intended as a guide and cannot embrace all of the aspects of this field.

Risk is determined by four factors:

Any surgery, even in a healthy individual, carries a risk of an adverse outcome, including death. The risk associated with a surgical procedure is the relative chance of an adverse outcome as a result of that surgery in a particular patient.

Adverse outcomes are difficult to define exhaustively. An adverse outcome may be as extreme as death from pulmonary embolism or the need for a previously fit and healthy individual to require full-time nursing care for irreversible hypoxic brain damage from a respiratory arrest. A lesser adverse outcome may be an extra day in hospital after a slight chest or urinary infection.

Good preoperative assessment also involves good communication regarding adverse outcomes with the patient. It is also important to identify any issues that the patient may see as an unacceptable adverse outcome and address these.

Accurate preoperative assessment can help determine the individual risk of adverse perioperative outcomes and should identify those patients in whom appropriate intervention may reduce the risk of such outcomes. It is important to assess the potential benefit of the contemplated surgery and weigh this against the potential associated surgical risk. The final decision to proceed to operation in patients with high risk of perioperative morbidity and mortality should be multidisciplinary. The patient, the surgeon, the anesthetist, and other members of the healthcare team may have to reach consensus that the potential benefits of surgery outweigh the potential associated risks.

Examples include the decision to proceed with non-lifesaving joint replacement in an elderly man with multiple medical comorbidities who has such severe, constant pain that his quality of life is so diminished that he is happy to accept a risk of death and disability to have a surgical cure for his pain. An opposite example would be not to proceed with nephrectomy in an asymptomatic woman with renal malignancy who is at high risk of perioperative morbidity and mortality because of medical comorbidities that are associated with a worse prognosis than the underlying malignancy.

These decisions can be very difficult. Where possible, it is important to seek expert help if there are questions of importance that involve individual organ systems to help decide on the timing of surgery and the appropriate preoperative optimization.

The risk of surgery encompasses many organ systems which may develop dysfunction, either individually or as part of multisystem organ failure.

“The final decision to proceed to operation in patients with high-risk of perioperative morbidity and mortality should be multidisciplinary. The patient, the surgeon, the anesthetist, and other members of the healthcare team may have to reach consensus that the potential benefits of surgery outweigh the potential associated risks.”

A vital element in any encounter between a health professional and a patient or their relatives is the ability to communicate. It is also true for communication between professionals.

An effective preoperative assessment involves many levels of communication. At the least, information that determines perioperative risk needs to be gathered, leading to decision-making. That decision then needs to be clear to the patient, healthcare team members, and any other relevant parties. Without effective communication the information gathered may be insufficient to accurately determine risk, or the decision may be poorly communicated to other members of the healthcare team. Either mistake may lead to an increased risk of an adverse outcome, rather than the desired decrease.

Without good communication, any effort put into appropriate preoperative assessment is likely to be wasted or less effective. The ability to communicate effectively is something that many people have learned over a lifetime. There are basic principles, however, that can be learned. A short summary on communication here should help emphasize the importance placed on this skill. It is beyond the scope of this chapter, however, to exhaustively outline the many communication skills that need to be mastered.

Preoperative assessment can involve clear lines of communication between many parties. The assessor may need to communicate with:

Communication objectives may range from ensuring patients are aware of the risk implicit with minor surgery, but understanding that there are no major problems likely to be encountered, to discussing the risk-benefit ratio of surgery in a terminally ill patient facing a palliative, but life-threatening, procedure.

Important facets of communication include:

Good communication, like good preoperative optimization, involves good preparation.

The first step is to define what needs to be communicated (the objective). This is the most important step and, if not defined prior to the communication, may make the conversation less effective. The manner of communication is next, as it is difficult in many settings to avoid being too technical, complex, detailed, simplistic, judgmental, patriarchal, matriarchal, patronizing, or any of the many other errors that may be made or may be perceived to be made. It is important to make the effort, however.

The correct environment, such as seeking a quiet place without interruption, e.g., from mobile phones, people, clatter, or nursing staff, is often important.

It is appropriate to also have an understanding of educational background of the person you are communicating with. For example, in discussion of the Delorme’s procedure with a surgeon, a nonmedical person, or someone who is unfamiliar with the procedure, each will need a different approach.

“Good communication, like good preoperative optimization, involves good preparation.”

It is important that communication occurs in a language and cultural context that is appropriate. This may involve the use of an interpreter. Although the family may offer to interpret, it is preferable to have a trained interpreter who should be trusted to transfer information without editing the information being relayed.

Cultural sensitivity is important. It may not be appropriate to discuss gynecological procedures with a Cambodian or Middle Eastern lady with a male interpreter or doctor. There are many other examples of where cultural misunderstanding can interfere with the ability to provide good quality healthcare. If communication is written rather than spoken, it is important to ensure information is sent within a time frame, to permit adequate reading time and comprehension.

The third step is to allow time for interactive questions and clarification. Communication should be a two-way process, to facilitate questions and understanding and detect any uncertainty or unwillingness of consent.

The final step is to ensure that all parties have understood the objective you wished to achieve. Briefly summarizing the outcomes and asking the patient to describe what they understand is a useful way to confirm this before the encounter finishes.

The first part of risk assessment is identifying high-risk surgery. It seems self-evident that an individual undergoing a major vascular procedure with a prolonged anesthetic time, major blood loss and fluid shifts, and increased cardiopulmonary stresses will have a greater risk of adverse events than the same individual undergoing cataract surgery.

The first question to answer then is what level of risk does the proposed surgical procedure carry?

In the emergency situation, there may be little opportunity to assess the patient preoperatively to improve postoperative outcomes. Once the type of surgery has been specified, the time line in which it is to be performed must be determined.

A critically ill patient needing immediate lifesaving surgery should not have their procedure delayed for tests which are unlikely to change the management. Appropriate preoperative assessment in this instance, however, includes recognition of the severity of existing illnesses, urgent preanesthetic optimization of the patient’s condition, and commencement of some postoperative planning such as the need for ICU admission. Sometimes, a short period of resuscitation is wise.

A patient awaiting surgery that is not life-threatening, such as elective joint replacement surgery, should have their surgery delayed when an increased risk of an adverse perioperative outcome is recognized, so that they may be improved by preoperative optimization.

The second question that needs to be asked is how urgent is the planned procedure?

The commonest severe adverse events after surgery are cardiac and include cardiac death, cardiac ischemia, and cardiac failure. These account for a significant burden of serious nonfatal adverse outcomes with surgery in the short term but are also markers for increased long-term mortality and morbidity.

There are many scales for assessing adverse cardiac outcomes following surgery. The simplest but highly reliable scale is the Revised Cardiac Risk Index proposed by Lee.

This involves assessing six individual risk factors. The risk of an adverse perioperative cardiac event is directly related to the number of risk factors present, regardless of when they occurred prior to the contemplated intervention:

The Gupta cardiac risk assessment tool is also validated and reliable. It is available online, which improves its utility (Arora et al. 2009a, b; Gupta et al. 2011) (http://​www.​qxmd.​com/​calculate-online/​cardiology/​gupta-perioperative-cardiac-risk).

The Detsky Revised Cardiac Risk Index is older and more complex but also a useful tool in preoperative cardiac risk assessment. There are also international guidelines to help determine the degree of risk involved in an individual having a surgical procedure, which also outline suggested preoperative cardiac investigations. (Detsky et al. (1986); Lee et al. (1999); Fleisher et al. (2007)).

Important questions to ask in association with identifying the above risk factors are:

The role of examination in cardiac preoperative assessment is important in excluding severe valvular lesions. The most important of these is aortic stenosis, which, if severe, is associated with a greatly increased risk of adverse cardiac events. It is the most common valvular lesion in the elderly, and the incidence of severe aortic stenosis is estimated to be around 4 % in those over 85.

Aortic sclerosis and stenosis are common in the elderly and are associated with an increase of approximately 50 % in the risk of death from cardiovascular causes and the risk of myocardial infarction, even in the absence of hemodynamically significant obstruction of the left ventricular outflow (Otto et al. 1999).

Electrocardiography is appropriate to perform in:

Echocardiography is appropriate to perform in patients with a history suggestive of left ventricular dysfunction (orthopnea, nocturnal dyspnea, dyspnea on exertion; see NYHA score later in this chapter). Echocardiography is also important in patients with a murmur felt to be of hemodynamic importance, especially in the case where significant aortic stenosis is suspected. Echocardiography should not be used routinely as it has low predictive value for perioperative outcomes.

There are less reliable scales for assessing adverse pulmonary outcome with surgery than there are for assessing cardiac risk.

One of the more accurate despite its simplicity is the ASA (see later in the chapter).

Other important pulmonary risk factors to take into consideration include:

A functional assessment of exercise tolerance is important in assessing respiratory reserve. If exercise tolerance is limited to being unable to walk two blocks or climb two flights of stairs, the risk of perioperative pulmonary complications is significantly increased.

The Epworth scale is an assessment of daytime sleepiness and is an easy assessment tool for the likelihood of obstructive sleep apnea being present. It scores sleepiness in eight settings. The scores are:

The settings asked about include:

The total is added up. A score greater than 8 may indicate need for further assessment for obstructive sleep apnea.

Examination is important to detect potentially reversible problems prior to surgery. Some important features to examine for include:

There is little evidence to support the routine use of pulmonary function testing, although it may be useful in particular individuals, e.g., severe asthma to guide adequacy of bronchodilator therapy. Patients with respiratory difficulty at rest or with minimal exercise are however of obvious concern, and the difficulty should be investigated, where possible, using spirometry to assess any reversible airway obstruction. Pulmonary function testing may also be useful in people with known lung disease to determine their ability to survive general anesthesia. If the FEV1 is less than 1 L, then the probability of prolonged postoperative ventilation is increased, thus increasing the probability of perioperative morbidity and mortality.

Arterial blood gases may be useful in some circumstances, where shortness of breath at rest or with minimal exercise, known lung disease, or cyanosis is present.

Patients with a PaO₂ in air of <70 mmHg must be considered for ventilatory support on high inspired oxygen concentrations. However, if their PaCO₂ is >45 mmHg, the patient should be considered for operation very carefully because when further respiratory depression from narcotic analgesics occurs, the PaCO₂ with likely rise to above 50 mmHg, and these patients may experience considerable hypercapnia.

CXR A history of a recent respiratory illness, a recent fall or rib fracture, fever, or known pneumonia will need to be investigated further with a CXR in addition to the clinical examination.

It seems self-evident that significant medical disease will limit exercise tolerance. Many measurements of function, such as New York Heart Association classification of heart failure, depend on assessment of limitation of functional tolerance.

Exercise capacity also correlates well with VO₂ max.

Exercise capacity has been shown to be predictive of outcome in thoracic surgery. Poor performance on assessment of self-reported exercise tolerance has also been shown to be associated with increased risk of surgical complications.

A useful self-reported measure is the ability to climb stairs. People able to climb less than two flights of stairs without stopping are at increased risk of perioperative cardiopulmonary morbidity and mortality. People able to climb five flights of stairs without stopping are at a very low risk indeed of perioperative morbidity and mortality (Reilly et al. 1999).

Examination and investigation may include a 6-min walk test or a trial of symptom-limited stair climbing. Stress testing with a well-defined protocol (e.g., Bruce protocol) on a treadmill is a more formal objective measurement of exercise capacity.

The development of deep venous thrombosis (DVT) and its more severe sequelae of pulmonary embolism (PE) is well recognized to be a complication occurring in the postoperative setting.

Risk for DVT/PE should be recognized in the preoperative setting, and a plan should be made for intraoperative and postoperative thromboprophylaxis.

Risk factors for DVT/PE include

Examination has a limited role in predicting thromboembolism risk. Investigation has a limited role in the preoperative setting, unless there is clinical evidence of DVT/PE acutely or in the recent past. If there has been an event in the recent past, baseline investigation may prove worthwhile, e.g., venous leg ultrasound to see extent of preexisting clot. Many hospitals have well-developed protocols for perioperative thromboprophylaxis, and there are well-established international guidelines for most types of surgery (Hirsh 2004; NHMRC Guidelines 2009). In some settings (e.g., hip and pelvic malignancy surgery), the indication for thromboprophylaxis extends beyond the hospital period for up to 35 days after surgery.

Postoperative delirium is an increasing problem in an ageing society. Delirium is associated with increased length of hospital stay and increased risk of cardiac and pulmonary morbidity and mortality.

Risk factors for delirium include:

Examination and investigation should include an assessment of a person’s cognitive ability. This may be as brief as orientation to time, place, and person and ability to answer questions in an appropriate chronological fashion. It may be more formalized and, for instance, include a “mini-mental” examination if there is significant concern regarding cognitive function.

One of the saddest outcomes, especially after elective surgery, is for a previously independent (elderly) person to be so deconditioned by a complicated hospital stay that they are unable to return to independent living and need to seek higher-level nursing home care. Especially in the elderly, fitness and muscle strength deteriorate quickly. Every day in the hospital reduces the ability to mobilize and perform activities of daily living without help. Perioperative complications increase hospital stay and are thus associated with increased risk of needing higher-level care. This risk is especially high in people who already have poor exercise capacity from their underlying problems. The problems may be the reason they have sought a surgical cure, e.g., limited mobility related to severe hip arthritis, or may relate to poor cardiopulmonary fitness. It is important to document a person’s exercise capacity prior to surgery and, if poor, recognize the need for increased rehabilitation or support early in the hospital stay to allow appropriate, timely, discharge planning.

Examination and investigation may include a formal assessment of exercise tolerance such as a 6-min exercise test of symptom-limited stair climbing. The Duke’s activity scale may also be useful as a measure of metabolic capability. The ASA also takes into account functional capacity and although simple is reliable in predicting poor outcome.

It is well recognized that the greater the reduction of renal function, the higher the risk of perioperative adverse outcomes. These adverse outcomes include renal dysfunction or progression to end-stage renal failure but also severe cardiac complications and death. It is therefore important to bear in mind that abnormal renal function is a strong clinical marker of increased perioperative risks. A history of renal dysfunction is important. Equally important is a history of vascular risk factors (hypertension, diabetes, smoking, hyperlipidemia, previous vascular disease) which may predispose to renal dysfunction and an increased risk of vascular disease. Many people, especially the elderly, may have unrecognized significantly reduced renal function detected in the preoperative assessment. A history excluding renal disease is therefore often inadequate without reassuring biochemical proof. Examination should include looking for A-V fistulae as dialysis access points.

Investigation should include the serum creatinine, which directly correlates with muscle mass. It is important to remember a normal serum creatinine may be associated with significant renal dysfunction in the frail elderly patient. A better marker of renal dysfunction is the glomerular filtration rate, which is calculated knowing the serum creatinine. There are many simple calculators for this, available online through www.​kidney.​org.​au.

The risk of surgery in elderly patients varies from mildly to greatly increased, determined largely by the underlying fitness of the individual patient, principally related to the existing comorbidities, in addition to the severity of the surgical problem for which surgery is being contemplated. Many elderly patients tolerate anesthesia and surgery well, with little difference from younger patients. Low body-weight and frail people, with cardiac, pulmonary, renal, hepatic, or hematological illness(es), are subjected to increased risk of surgical and other complications. Tissue strength and repair is frequently reduced with advancing age, as is agility and readiness to mobilize after surgery and bed rest. Hepatic and renal impairment is common, which may alter drug metabolism and the required doses for anesthetic and other agents. Confusion and delirium are relatively more common also with advancing age. The need for postoperative prolonged rehabilitation or need for higher-level care may also be important to recognize. The main impact of surgery and postoperative complications is on existing multiorgan dysfunction, which may be appreciable, but sometimes previously unrecognized before the preoperative assessment for surgery. Tolerances to therapeutic manipulations are also frequently reduced in elderly patients with reduced capacity to respond to fluid loads, iatrogenic, or otherwise due to cardiac, renal, and pulmonary disease.