Risk Assessment

Risk assessment of patients serves several important functions:

I. Identification of pre-existing comorbidities and potential improvement of these prior to surgery

II. Accurate risk stratification allows for improved patient understanding and informed consent

III. Provision of services and resources (including the availability of higher dependency post-operative care)

IV. Audit and assessment of surgical performance against predicted standards

V. Provision of an appropriate forum to undertake detailed information sessions for the patient

VI. Identification of patients that are either unsuitable for or unwilling to undertake operative management

Patient assessment prior to surgery should employ a multidisciplinary approach. Whilst current guidelines do not dictate how to undertake such assessments, it is widely accepted that a thorough medical history and clinical examination combined with appropriate use of investigation is mandatory¹³. Risk stratification tools are essential and can help identify those at most risk, such as those with malnutrition for nutritional support or sarcopenic patients for targeted exercise programmes.

Optimisation

In the period between diagnosis and the date of surgery there is a window to address the modifiable risk factors and influence beneficial lifestyle changes. Sub-specialty opinion on chronic disease management including heart disease, respiratory disease, kidney disease, hypertension and diabetes should be undertaken to ensure optimisation prior to surgery.

Patients should be encouraged to stop smoking. Current smokers are three to six times more likely to suffer a pulmonary complication and smoking cessation prior to surgery has been demonstrated to reduce this risk as well as improve wound healing^14,15. Equally, while the evidence base for alcohol avoidance is less developed, studies do suggest that excess alcohol consumption (defined as more than 2 units of alcohol a day) may be associated with increased rates of post-operative infections¹⁶.

Anaemia is common in patients undergoing colorectal surgery and can be attributed to luminal bleeding, Vitamin B12 and folate deficiency or the result of chronic disease³. There is association with significant morbidity and mortality. Furthermore, perioperative transfusions are associated with surgical site infection, septic shock and have an adverse effect on overall survival in a colorectal cancer cohort¹⁷. Correction of anaemia can be effectively and safely achieved using intravenous iron negating the need for blood transfusion³.

Prehabilitation

Prehabilitation is a multimodal intervention, aimed at augmenting an individual’s functional capacity in anticipation of a forthcoming stressor. It may be likened to an athlete training for competition and includes nutritional optimisation, physical exercise programmes and targeted psychological intervention.¹⁸

The ERAS^® society recommend prehabilitation exercise programmes that target:

I. Aerobic capacity

II. Muscle strength and endurance

III. Daily physical activity

Studies employing such programmes and incorporating nutritional and psychological interventions have demonstrated improved physiological reserve prior to surgery and sustained post-operative functional capacity¹⁹ (Fig. 1). It is recommended that such programmes are designed, delivered, and supervised by a trained appropriate medical professional and are specifically tailored to an individual’s functional status and capacity²⁰.

Figure 1 Trajectory of functional capacity in the cancer care continuum showing sustained advantages into the postoperative period from prehabilitation (Minnella et al. 2017)¹⁹. 

Malnutrition results in increased morbidity, mortality and poor oncological outcomes, yet 25- 40% of patients are malnourished on admission to hospital²¹. Nutritional interventions commenced prior to surgery have been demonstrated to reduce risk of post-operative infection, reduce rates of anastomotic leak and shorten length of stay^22,23.

Evidence for improved outcomes following acute psychological intervention (including relaxation exercises, role play and stress management techniques) is less well established, but such interventions show improved quality of life outcome measures, depression scores and body image assessments²⁴.

Prehabilitation is an intervention that is in its nascency and the science is continually evolving. In particular, the greatest potential benefit comes to patients who are most at risk and it is crucial that further work is done to explore such programmes.

Antiemetics

Post-operative nausea and vomiting (PONV) are both very common - 30% and 50% respectively for all surgical patients³. It may result in dehydration, delayed return of adequate nutrition intake, or it may necessitate the placement of a nasogastric tube, increased intravenous fluid administration post-operatively, prolonged hospital stay, and increased healthcare costs³. The causes are multifactorial and these can be categorised into patient, anaesthesia and surgical-related factors. Those at more risk of developing PONV should be established at the pre-operative risk assessment and up to 3 multimodal antiemetics should be used in those with ≥ 2 risk factors^3,25.

Anxiolytics

Evidence suggests that pre-operative education addresses the issue of psychological distress prior to surgery and can bring patient anxiety to an acceptable level to avoid the need for anxiolytic medication²⁶. The use of routine sedative medications should be avoided as side-effects from opioids, beta blockers and especially benzodiazepines are shown to be detrimental. The ERAS^® guidance suggests the use of opioid sparing pre-anaesthetic drugs in a multimodal fashion such as acetaminophen, NSAIDS and gabapentinoids.³

Antimicrobial Therapy and Mechanical Bowel Prep

These two items are considered together as studies have incorporated the use of antibiotic prophylaxis combined with mechanical bowel prep (MBP) as a means to reduce bacterial load. Antibiotics both in systemic and oral form reduce the risk of surgical site infection from 39 to 13%²⁷. Consideration should also be given to the gut microbiome which is thought to play an integral role in post-operative ileus and anastomotic leak, newer studies are addressing the potential advantages that antibiotics confer towards this²⁸.

The ERAS^® recommendation is to use a cephalosporin in combination with metronidazole, systemic antibiotics should be given as a single dose 60 minutes prior to incision³. The use of antibiotics in the oral form are recommended only when MBP is given. MBP alone in colonic surgery is of no benefit and may have potential negative effects in terms of fluid and electrolyte disturbance prior to surgery, as well as being unpleasant²⁸. Practically, there may be some benefit of MBP in rectal surgery, which will avoid stool remaining in a diverted colon if a defunctioning ileostomy is planned. A rectal enema, may be just as efficient for this and carries little or none of the risks of MBP²⁸.

Fluid Assessment

Fluid and electrolyte levels should be assessed throughout the perioperative period. A patient should arrive at theatre in a euvolaemic state. Prolonged fasting preceding surgery can be avoided and patients should be allowed to drink non-alcoholic clear fluids up to 2 hours before and a light meal should be allowed up to 6 hours before³. If MBP is used then this may incur a negative fluid balance by as much 2L - intravenous fluid therapy to correct may be warranted.

Carbohydrate drinks improve pre-operative well-being, reduce post-operative insulin resistance, decrease protein breakdown and better maintain lean body mass and muscle strength, as well as beneficial cardiac effects^3,29. They come as a clear fluid and can therefore be taken up to 2 hours prior to surgery.

Standard Anaesthetic Protocol

Choice and use of anaesthetic agents will impact the early post-operative period. Propofol allows for rapid awakening and one should avoid benzodiazepines and only use the short-acting class of opioids if required to reduce post-operative delirium.³ Evidence is limited, but there is a high recommendation to use total intravenous anaesthesia (TIVA) with Propofol, as anaesthetic gases may increase PONV. The use of the bi-spectral index for cerebral function monitoring will reduce the risk of awareness and avoid overdose and delirium, which is a particular risk in the elderly³⁰.

Deep neuromuscular blockade allows the surgeon to operate with lower intra-abdominal pressures. Careful monitoring is required with acceleromyography as poor reversal can increase the risk of pulmonary complications from residual paralysis³. Higher pressures will worsen cardiac function, impede ventilation and reduce renal blood flow³¹. Intrabdominal pressures as low as 8mmHg can be achieved and this is associated with a physiological improvement that leads to faster recovery, fewer intraoperative complications and less inflammation³².

Surgical Access

Perhaps the greatest change since the concept of ERAS^® is the increased use of minimally invasive surgery (MIS). Colorectal resections are now well-established in the form of MIS and it is the standard of care in many countries³. The majority of evidence is in the comparison of laparoscopic versus open surgery. Three Cochrane systematic review articles have demonstrated that laparoscopy confers advantages to recovery, length of stay, blood loss and complications for colonic and rectal resections^33-35. Oncological recurrence rates did not show any significant differences^34,35. A large national audit in Holland, covering 2010-2013, revealed that laparoscopic resection had significantly lower 30- day mortality³⁶.

More recently, advanced MIS techniques for total mesorectal excision have been taken up in the guise of robotics and transanal approach (TATME). The focus for the different MIS formats is in improving cancer-related outcomes, reducing morbidity of pelvic surgery and reducing conversion rates³. A systematic review from 2019 of 29 RCTs and meta-analysis of 6237 patients compared all four modalities for rectal resections (open, laparoscopic, robotic and TATME). It concluded that laparoscopic and robotic surgery may improve post-operative recovery, but open and transanal approach may gain better oncological resection³⁷. The evidence for these two newer techniques of robotic and TATME approaches is still in the early stages, and the paper itself admits to areas of bias across the board. The meta-analysis only had 50 patients in the TATME arm and actually a recent review from Norway worryingly revealed a more than double rapid recurrence pattern in 10% of patients³⁸.

The newer equipment required for both robotic surgery and TATME is expensive with higher running costs per case and the cost-effectiveness vs the current standard of care in laparoscopy is a crucial aspect for consideration³⁹.

Ultimately, no one form of MIS is yet to demonstrate clear superiority, but MIS in itself is strongly recommended by ERAS^®. MIS enables many of the elements for ERAS^® and is an independent predictor of good outcome by reduced pain, early mobilization, less impact on fluid shifts and reduced ileus³. Ultimately, the outcome is not purely down to the method chosen, but it is individual surgeon’s technical ability to use that method. Good surgery will minimise tissue trauma and achieve the operation in a timely, yet safe manner to reduce immediate complications and surgical stress response.

Further Intraoperative Recommendations

I. Avoid pelvic and peritoneal drains

II. No routine nasogastric drainage

III. Careful monitoring of core temperature and maintenance above 36 degrees with warming devices

IV. Avoid intravenous fluid overload by aiming for a near-zero fluid balance

Analgesia

Multimodal post-operative analgesia, achieving adequate pain control with the avoidance of opiates, is fundamental to the ERAS® approach. This enables early mobilization and is associated with a faster return of bowel function, reduced morbidity and shorter length of stay³.

Paracetamol and non-steroid anti-inflammatory drugs (NSAIDs) should be routinely used. Although there are concerns for association of NSAIDs with anastomotic leak, this data remains unclear and so guidelines currently support their use. Some research is now focusing on selective NSAIDs, which may prove a useful adjunct⁴⁰. There are many other options under consideration, including lidocaine infusion, dexmedetomidine and ketamine, however the optimum approach is not yet defined.

Thoracic epidural, containing local anesthetic and lipophilic opioid, was the gold standard in the era of open surgery; associated with reduced cardiopulmonary complications, ileus and mortality⁴¹. However, with the widespread implementation of minimally invasive colorectal surgery there has been a shift of focus. Technical issues have become more relevant as outcome measures are no longer superior, these include failure and lumbar placement, increasing risk of urinary retention and lower limb paralysis⁴². Thoracic epidural anaesthesia may still be considered where there is a high risk of conversion; but is largely superseded by other adjuncts such as spinal anaesthesia, lidocaine infusion and local wound infiltration. Transversus abdominus plane (TAP) blocks, targeted between the transversus abdominus and internal oblique muscles, is one adjunct that has been widely implemented. They are limited by a relatively short half-life and act only for incisions below the level of the umbilicus, but may reduce opiate consumption and the risk of urinary retention⁴³.

Post-operative fluid and electrolyte therapy

There is not universal consensus on post-operative fluid therapy, however the aim is to maintain a balance close to zero. Oral fluid should be encouraged when patients are awake and free of nausea, and intravenous fluid administration stopped on the day of surgery. It is important to recognise when patients are hypovolemic or unable to maintain adequate fluid intake, so that supplementary fluids can be considered as outlined on Table 1. When evaluating fluid status, oliguria should be considered with caution: it can result from the surgical stress response and should not be an indication for fluid resuscitation alone.

Table 1 Fluid selection in post-operative colorectal patients 

Nutritional Care

Historically, after colorectal resection patients were starved for extended periods with routine nasogastric tube placement. This is against the principles of the ERAS^® approach and no longer followed: nasogastric tubes should not be routinely used, and a Cochrane review demonstrates that early oral feeding is not only safe but may be associated with reduced morbidity.⁴⁵ If tolerated, nutritional supplements can be prescribed from the day of surgery to minimize the negative protein and energy balance, and immunonutrition should be considered in malnourished patients⁴⁶. Despite initial concerns, early oral nutrition is not associated with increase in ileus. Data now shows that an established ERAS^® protocol, including all these elements described, is the most effective measure to prevent ileus. Interventions that do not cause harm, for example chewing gum and coffee, can be considered but have no proven efficacy^3,47. The ERAS^® protocol also limits post-operative hyperglycemia, through a reduction in the surgical stress response and associated insulin resistance. However, in cases of persisting post-operative hyperglycaemia, insulin can be considered to reduce infective complications.

Urine Drainage

Early catheter removal is associated with lower rates of urinary retention and recommended to enable early mobilisation and reduce the risk of urinary tract infection⁴⁸. Selective delayed removal to the 2nd or 3rd day may be applied to higher risk groups, including rectal surgery, male patients and those with epidural anaesthesia⁴⁹.

Thromboprophylaxis

It is well established that all surgical patients should receive mechanical and pharmacological thromboprophylaxis while in hospital to reduce the risk of deep vein thrombosis. Current data supports the administration of extended (28 day) low molecular weight heparin after resection of abdominal and pelvic cancer⁵⁰. It is not clear whether this benefit will confer to laparoscopic surgery and so this recommendation may change.