Definition

Sedation is the term used to describe a continuum of a drug-induced state from normal alert consciousness to complete unresponsiveness. Surgeons may be exposed to sedated patients in the operating theatre, on the ward, in the emergency department and in the endoscopy suite (where procedures include upper and lower GI tract endoscopy, bronchoscopy and cystoscopy). In addition, there may not be an anaesthetist present when a patient under the care of a surgical team is sedated. Therefore, an understanding of this topic is essential to minimise risk and maintain patient safety.

Levels of sedation have been defined by the American Society of Anesthesiologists (ASA), and are often referred to as levels 1 to 4:

1. Minimal sedation (or anxiolysis). This is a drug-induced state during which patients respond normally to verbal commands. Cognitive function and co-ordination may be impaired, but cardiovascular and respiratory function will be unaffected.

2. Moderate sedation/analgesia (or ‘conscious sedation’). This is a drug-induced state that results in reduced consciousness. Patients will respond to verbal commands and no interventions are required to maintain a patent airway. Cardiovascular function is usually maintained.

3. Deep sedation/analgesia. This is a drug-induced depression of consciousness during which time patients cannot be easily roused but do respond purposefully following repeated or painful stimulation. There may be impairment of independent ability to maintain ventilation and patients may need assistance in maintenance of a patent airway with spontaneous ventilation being potentially inadequate. Cardiovascular function is maintained.

4. General Anaesthesia. This is a drug-induced loss of consciousness. Patients are not rousable, even with painful stimulation. Patients will generally require assistance maintaining patent airway and positive-pressure ventilation may be required. Cardiovascular function may be impaired. General anaesthesia also requires amnesia, unlike the previous three levels where it is optional. Additionally general anaesthesia concerns itself with analgesia too.

There are three main groups of patients presenting for colorectal surgery – those with intractable severe inflammatory bowel disease (IBD), those with malignancy, and those with benign anorectal problems. This chapter will concentrate on the first two patient groups.

Enhanced recovery has become synonymous with improved outcomes, shortened hospital stay, and improved patient satisfaction. The vast majority of research on enhanced recovery started in colorectal surgery. Many of the practices in care pathways, anaesthetic technique and post-operative care have subsequently been adopted by other surgical specialties.

Pre-operative assessment – general considerations

Pneumoperitoneum

The majority of major abdominal and pelvic colorectal surgery is now performed laparoscopically or with laparoscopic assistance. All patients must be assessed to see if they will tolerate:

i. Pressure effects of a pneumoperitoneum

ii. Physiological challenges of a pneumoperitoneum

iii. Physiological effects of steep Trendelenburg position

Nutrition and electrolytes

All patients are at risk of malnutrition and electrolyte imbalance. Specialised dietetics advice, and involvement of gastroenterologists will avoid complications and improve post-operative recovery. The malnutrition can be chronic and requires careful management of the ‘starved’ individual to prevent re-feeding syndrome or liver failure with nitrogen overload.

Items to consider specifically are:

i. Potassium (diarrhoea and vomiting), causes cardiac rhythm problems

ii. Magnesium (malabsorption), causes cardiac rhythm problems and muscle weakness

iii. Sodium (if on i.v. replacement fluids or sodium-depleting drugs)

iv. Albumin (indicator of liver function, healing problems, infection risk), important when considering whether to restore intestinal continuity with an anastomosis

v. Liver function (alters drug metabolism)

Methods used to aid clot formation

Agents derived from blood products

Fresh Frozen Plasma (FFP)

Contains factors II, V, VII, IX, and XI: useful in acute active haemorrhage.

Cryoprecipitate

Replacement of fibrinogen in the acutely bleeding patient (especially in DIC – fibrinogen consumption): also useful for von Willebrands, and factor VIII and XIII replacement.

Prothrombin complex concentrate – Octaplex, Beriplex

Used for rapid reversal of warfarin anticoagulation pre-operatively or during haemorrhage. Derived from human plasma and contains factors II, VII, IX and X. Effects last six to 12 hours.

Recombinant Factor VIIa

Originally used in the treatment of haemophilia, but use has transferred into the management of major haemorrhage from trauma and surgery.

It enhances thrombin generation on platelet surface at the site of injury, thereby inducing clot formation via tight fibrin plug and haemostasis.

Drugs

Vitamin K

Useful for reversal of warfarin but it has a slow onset and long duration of action, which can cause problems in those patients that require anticoagulation after major bleeding has been terminated.

Tranexamic acid

Antifibrinolytic, which competitively inhibits activation of plasminogen, reducing conversion of plasminogen to plasmin – the enzyme that breaks down clots.

Nerve injury is one of the leading causes for settled cases of litigation. Medical Protection Services data have shown that of all the cases that are recorded, 75% proceed to a claim for medical negligence. The incidence of nerve damage has been described as between 1:1,000 or as frequent as 1:350 cases.

The nerves most often affected are ulnar (30–43%), brachial plexus (25%), lumbosacral roots (16%) and common peroneal (11%). It has historically been considered that stretch and pressure effects on nerves are the predominant cause for nerve injury. Many retrospective studies looking at closed claims analysis have called this in to question, yet it remains the most often blamed cause for injury. Analysis of cases in studies has shown that many factors play a contributing role in the development of nerve injury. Some patients (the elderly, frail, diabetic, hypertensive, anaemic patient) can be identified as at greater risk, and extra care and attention can be placed on reducing the additive problems of pressure and stretch.

It is also interesting to note that cases of peripheral nerve injury may have a delayed presentation and are not often apparent in the recovery room. Most present within the first 24 hours, and over 90% present within seven days post-operatively. About 60% of patients with a nerve injury will recover within a year, but a quarter will suffer persistent pain.

Nerve injury can be caused by excessive stretch of nerves or plexi; pressure injury because of poor positioning; direct injury by needles or sharp surgical instruments; chemical injury because of local anaesthetics or antiseptic solutions.

Anaesthesia is one of the major determinants of a successful outcome after neurosurgical procedures. Pre-operative assessment, induction of anaesthesia, maintenance of anaesthesia, the process of extubation, and immediate post-operative care are interlinked and enable surgery to proceed smoothly. Good neuroanaesthesia produces a relaxed brain and optimal operating conditions. Additional manipulation of the patient’s physiology may be necessary according to the procedure. The care of the patient and the maintenance of a favourable intracranial/intraspinal environment remain with the anaesthetist into the recovery room and, at times, the intensive care unit.

Pre-operative assessment

The anaesthetist faces a number of challenges when assessing the neurosurgical patient.

1. Many patients will be transferred as an emergency directly to theatre from other hospitals. Communication regarding the patient’s intracranial pathology, the proposed position for surgery and the expected time of arrival can speed the time to incision, and allow the anaesthetist to prepare for the case. Excellent communication between the transferring and receiving team is essential. It must include the patient’s medical history as far as is known, mechanism of injury, neurology at scene, treatments received so far, and other injuries identified. Limited information will be available from blood investigations.

2. Patients with intracranial pathology may have receptive or expressive dysphasia, a low GCS, neuropsychiatric disorders or capacity issues.

3. Patients with low GCS, or neurological weakness of whatever cause do not exert themselves physically and assessing cardio-respiratory reserve is a challenge.

4. Patients with sudden acute elevation of intracranial pressure can have a ‘sympathetic surge’ and subsequent myocardial events – myocardial infarction, Takatsubo (stress-induced) cardiomyopathy, arrhythmias.

5. Patients frequently require surgery without delay to avoid devastating complications – paralysis, blindness and death. Conditions that can be readily optimised should be; conditions that require lengthy investigation or treatment will often be postponed until after surgery, if it is safe to do so.

The enhanced recovery project has been embraced by almost all surgical specialties. The programme purports to offer benefits to all end users. What is apparent is that it involves, and requires engagement of every person involved in the patient pathway. The success of the programme does not exclude the patient nor their care-givers.

Proposed benefits of employing an enhanced recovery programme

General practice

• Closer working relationships between the acute and primary care sectors – with recognition of good care from local commissioning groups

• Family physician able to start the process of preparation for surgery, and get ready to receive the patient back with good information post-operatively

Patient

• More involved in their care

• Earlier return to home and/or work

• Purported to have less exposure to hospital-acquired infection, and lower complication rates post-operatively

Staff

• Education and training

• Implementation of technology to support care

• Sense of achievement and recognition about providing excellent care with reduced lengths of stay, and improved patient experience

Quality

• Allegedly improved clinical outcomes, faster detection of complications and standard care across the UK

• It is certainly something that can be measured by both hospital mangers and inspecting bodies