Patient assessmentand surgical risk

Introduction

Few patients do not survive an operation, but many will incur significant morbidity around the time of surgery. These adverse outcomes are considered together as perioperative risk . Patient assessment is the process of gathering information to determine the particular risk for a given individual undergoing an operation, which carries distinct procedural risks . Care of the patient is also dependent on the system in which that care is being delivered. Managing these system risks is key, and one of the most important functions of multidisciplinary preoperative risk assessment is to inform perioperative care planning for the patient.

Why is assessing risk important?

Informed consent cannot be obtained without an estimation and communication of risk. This must include both the risk of the procedure itself and the competing risk of non-intervention. Conveying risk should also help the patient to form reasonable expectations for the perioperative and recovery process. Assessment of risk helps clinicians, in discussion with patients, to make better decisions when considering if a surgical procedure or intervention is appropriate for a given patient with a particular clinical need. Surgical technique has advanced significantly resulting in shorter and less invasive procedures, allowing patients with higher levels of comorbidity to be considered for surgery. However, it is important to remember that surgery is not always appropriate for all patients.

Despite improvements in surgical tools and technique, complications remain common. Planning the patient’s journey through the hospital to allow timely recognition and management of these complications will reduce resulting morbidity. The best performing high-volume centres often have similar complication rates to low-volume centres, but achieve better outcomes due to robust early warning systems when a patient deteriorates triggering prompt clinical action, i.e. a low rate of ‘failure to rescue’. Risk assessment informs pre-planned perioperative management strategies, e.g. provision of postoperative critical care resources. As part of this process, identification of specific risks may also allow for pre-optimisation (also known as pre-habilitation) covered elsewhere in this book.

Adjusting for the level of risk present within a case-mix also allows for a fairer comparison of local or individual surgical outcomes against national standards.

It is therefore essential that clinicians endeavour to accurately estimate risk on an individual patient basis for every patient, particularly for those patients who are either comorbid and/or undergoing a major surgical intervention and are therefore considered to be high risk.

What are we aiming to identify in risk assessment?

Our aim is to identify the higher-risk patient, generally accepted to be any patient who has an estimated perioperative 30-day mortality of greater than 5%. Perioperative risk is a broad term which can be thought of as a combination of:

• Patient risks : not related to the surgery per se, but specific to that individual patient

• Procedural risks : related to the surgery itself and the anaesthesia required, and which would apply to any patient undergoing that procedure

• Systems risks : quality of preoperative investigation/optimisation and perioperative care

Procedure-related risks are generally easier to identify and communicate. The development of surgical quality improvement programmes has allowed a more accurate appreciation of procedural complications and the rate at which they are encountered on a national, local or even individual surgeon level. Examples include rates of haemorrhage, infection, nerve damage or anastomotic leak. These procedure-related risks are also dependent on other factors, such as urgency and duration of the procedure, volume of blood loss and type of surgery undertaken. The National Institute for Health and Care Excellence (NICE) has attempted to stratify surgical procedures into different grades of severity to provide guidance on the use of preoperative investigations and estimate perioperative risk ( Table 4.1 ).

Patient-related risks are more complex, and thus more challenging to identify and communicate, as they are usually due to individual disorders of physiology. This may lead to an increased risk of a complication less commonly observed in the healthy population. For example, patients with chronic obstructive lung disease (COPD) could reasonably be expected to encounter postoperative pulmonary complications (PPCs) more frequently. Alternatively, it may lead to a decreased ability to tolerate a known complication of a specific procedure, e.g. a patient with significant cardiac disease may fail to tolerate the expected degree of haemorrhage, even if relatively moderate. Patient-related risks may be broadly classified as:

• Major adverse cardiac events (MACEs)

• PPCs

• Perioperative acute kidney injury (AKI)

• Perioperative cerebrovascular events and cognitive dysfunction

• Other morbidities such as urinary tract infection, surgical site infection (SSI) and venous thromboembolism

• Other risks related to an individual’s other underlying disease processes, functional status or nutritional status

Systems-related risks include seniority/experience of clinicians, availability of diagnostic investigations such at CT imaging, rapid access to emergency operating theatre, and provision of perioperative critical care. These risks are modifiable and many healthcare systems now have robust standards and quality improvement projects to assess compliance with accepted standards of best practice. Examples include the UK National Confidential Enquiry into Patient Outcome and Death (NCEPOD), and more recently the National Emergency Laparotomy Audit (NELA). This subject is discussed in detail in Chapter 3 .

How do we assess risk in the elective setting?

The timescale of non-urgent operating allows for robust risk calculation. For many patients, the process can be completed at the initial clinic consultation, based on an accurate history and examination augmented with basic point of care, laboratory and radiological investigations. The majority of low-risk patients will not require more than this and can be quoted the usual procedural risks. Although there is evidence that the gut instinct of an experienced surgeon may be more effective than risk modelling tools, ^, modelling has become more sophisticated since these studies were undertaken and many tools are now used routinely to help predict risk for patients with chronic conditions undergoing major complex procedures.

It is important to remember that most available tools predict risk as a 28-day or 30-day mortality and/or morbidity figure. This is an accepted standard within surgical practice and is useful for quality improvement work, but most patients will expect to survive for more than 28 days after their operation and will expect to return to at least their preoperative quality of life. The risk of longer term or permanent impairment to quality of life is a key consideration in undertaking the process of informed consent, particularly after the landmark Montgomery vs. Lanarkshire Health Board UK Supreme Court decision. This ruling has changed the requirements of the process of informed consent, such that it must now include communication of all risks, no matter how small, if they could be deemed to be of significance to the patient.