Perioperative Medicine
The Future of Anesthesiology
Prehabilitation & Optimization
Lee LKK, Tsai PNW, Ip KY, Irwin MG. Pre-operative cardiac optimisation: a directed review. Anaesthesia. 2019;74 Suppl 1:67-79. doi:10.1111/anae.14511
Bottom line: This 2019 review discusses pre-operative optimization in four patient populations: hypertension, chronic heart failure, cardiac murmurs and implantable electronic cardiac devices. All the above conditions can to an extent be considered modifiable risk factors pre-operatively and should be identified early on in the pre-operative course so that management can be initiated or titrated with the ultimate goal of reducing risk of post-operative complications.
Major points:
1. Hypertension is a minor risk factor that corresponds to volatile intra-operative hemodynamics, but the latter has not been associated with increased 30-day mortality. Varying levels of evidence exists for the management of the numerous anti-hypertensive medications – this article provides a great summary for each (beta-blockers, alpha-2 agonists, CCBs, nitrates).
2. Consider delaying major elective surgery if patient has a pre-op systolic > 180 or diastolic > 110 to allow for appropriate management. If long-standing hypertension is identified, look for signs of end-organ dysfunction: LV dysfunction, diastolic dysfunction, CAD, heart failure, renal damage.
3. Chronic heart failure is an independent prognosticator in all cardiac risk scores. Detailed history and clinical examination should be used to identify the severity of the condition. NYHA Class IV patients should have their surgery postponed and receive a cardiology opinion on further medical management. Most guidelines suggest monitoring BNP or NT-proBNP levels pre-operatively, but it still remains unclear how to specifically tailor management in those with elevated levels. It is reasonable to monitor post-operative troponin levels in the high risk patients as post-operative MIs are more likely to be silent.
4. Clinical exam alone is neither sensitive nor specific for evaluating cardiac murmurs. There is some evidence for anesthetist-led pre-operative echocardiography which, in 10 minutes, can: detect significant valvular lesions, assess RV/LV function and detect pericardial effusions. This does not replace a formal echo nor a detailed cardio consult. Furthermore, in a study of 250,000 patients undergoing intermediate/high-risk surgery, pre-op echo did not improve survival nor shorten LOS – putting into question its utility for improving perioperative outcomes.
5. The main risk with implantable cardiac electronic devices that certain procedures with provide high levels of electromagnetic interference (EMI) which can adversely affect pacemakers (inhibiting them from fire leading to bradycardia/asystole) and implantable cardioverter defibrillators (leading to an inappropriate shock delivery). Pacemaker-dependent patients undergoing procedures at high-risk of EMI, should have their device reprogrammed to asynchronous mode. Implantable cardioverter defibrillators in high-risk EMI procedures should be programmed to suspend anti-tachycardia mode. No device reprogramming is required for surgeries below the umbilicus. When device reprogramming is required, it should be done by a trained personnel using a device-specific machine.
Poulton T, Murray D; National Emergency Laparotomy Audit (NELA) project team. Pre-optimisation of patients undergoing emergency laparotomy: a review of best practice. Anaesthesia. 2019;74 Suppl 1:100-107. doi:10.1111/anae.14514
Bottom line: This review article highlights the important differences in pre-optimizing patients undergoing emergency laparotomy compared to elective surgery patients. Given the time-sensitive (50% of emergency laparotomy patients need surgery within 6h) nature of emergency laparotomies, the time needed to correct any abnormalities (e.g. electrolytes, fluid status etc.) need to always be balanced with the urgency of the surgery. In the most urgent cases, the correction of abnormalities and the surgery itself may need to occur simultaneously. Home medications need to be reviewed carefully: continued where appropriate and discontinued when harmful. The hospital needs to adopt robust systems to make it difficult to deviate from good care, and ultimately ensure that there are minimal delays in the surgical pathway.
Major points:
1. Timely antibiotics need to be given in anyone suspected of sepsis regardless of surgical timing. Patients with massive hemorrhage should receive early, balanced transfusions (as opposed to restrictive transfusions) especially if in shock or have on-going bleeding. Routine use of TXA, thromboelastography, and avoidance of hypothermia, acidosis and coagulopathy all play a role in improving outcomes in hemorrhaging patients. Fluid resuscitation needs to be individualized to the patient’s condition and comorbidities – balanced crystalloids are almost always preferred over 0.9% NaCl and vasopressors should be considered when appropriate (e.g. septic shock).
2. Medications should be reviewed carefully in order to discontinue harmful medications, like nephrotoxins (e.g. ACEi/ ARBs), and replace necessary meds that cannot be given PO in the critically ill patient (anti-epileptics, Parkinson’s Disease, immunosuppressant medications). Only discontinue anti-coagulants and anti-platelets after finding out why they were initially prescribed (for e.g. mechanical aortic valve patient may require bridging). Plan for parental nutritional therapy early on for the highest-risk patients (unable to eat for 5 days post-op or cannot maintain 50% of nutritional requirement for next 7 days). Aim for slightly higher target glucose values with IV insulin at 6-10 mmol/L and even 12 mmol/L if difficult to control. In diabetics, continue with 80% of home SC insulin dose in addition to IV insulin as needed.
3. The surgical care pathway should be optimized to avoid unnecessary delays as these are associated with lower survival rates. Timely access to radiological services is important: target for CT scan should be <15 mins and read within the hour. IR can help reduce rates of emergency laparotomy altogether. Standardization of processes within a hospital can help reduce variations from the standard of care. However, there is no single surgical pathway that works best – solution will be unique to each hospital’s unique ecosystem.
4. Assume the patient is high-risk until clinical judgement and risk prediction scores say otherwise. Use P-POSSUM or NELA to help risk stratify but recognize that overall 30-day mortality in emergency laparotomy patients is 9.5% so most patients are already high-risk. These tools however, can help with discussions around informed consent. There needs to be early input from surgery, anesthesia (and ICU or geriatrics where applicable) to ensure the right procedure takes place, at the right time, with the right personnel present and the right facilities available.
Levy N, Grocott MPW, Carli F. Patient optimisation before surgery: a clear and present challenge in peri-operative care. Anaesthesia. 2019;74 Suppl 1:3-6. doi:10.1111/anae.14502
Bottom line: This editorial article acts as the foreword to the January 2019 107-page Anaesthesia Supplement titled “Special Issue:Patient optimisation before surgery” (Volume 74, Issue 1).
The author defines prehabilitation as the “identification of impairments of the patient who is being considered for major surgery [as well as providing] interventions that promote physical, metabolic, and psychological health to reduce the severity and/or incidence of these impairments.”
The 10 review articles combine to form a 107 page supplement which provides the most up-to-date evidence and expert opinion on: risk prediction models, shared-decision making, nutrition, psychological prehabilitation, respiratory and cardiac optimisation, management of the pre-operative diabetic patient and anemic patients, management of frail/eldery patients, patients undergoing emergency laparotomy as well as how peri-operative care pathways can be optimized.
Levy N, Dhatariya K. Pre-operative optimisation of the surgical patient with diagnosed and undiagnosed diabetes: a practical review. Anaesthesia. 2019;74 Suppl 1:58-66. doi:10.1111/anae.14510
Bottom line: Diabetes mellitus is the most common metabolic condition, afflicting 1 in 11 adults (with 90% of them having Type 2 DM), and is associated with longer LOS (45% longer in some studies), more major complications and higher mortality rates (twice as high in some studies). There is increasing evidence that diabetes mellitus is a modifiable peri-operative risk factor, whose optimisation has the potential to decrease perioperative morbidity and mortality. Diabetes optimisation begins from the moment the primary care referral is sent.
Major points:
1. Poor pre-operative glycemic control is associated with harm especially in those with previously undiagnosed diabetes. Poorer outcomes begin even in the pre-diabetic range (HbA1c ~ 6.0%). Given ethical considerations, there is limited data (except in liver and cardiac surgery, and surgical-site infections) that compares in a head-to-head fashion: no treatment vs close treatment in the poorly controlled pre-operative diabetic patient. Despite this, it is still “intuitive” to optimize HbA1c given its association with harm.
2. Diabetes is associated with multiple comorbid conditions -- including cardiovascular disease, peripheral vascular disease, renal disease, hypertension, obesity. There is evidence that in most of these conditions the patients with less severe condition have better outcomes compared to those with the same, but uncontrolled condition. This suggests that optimising pre-operative comorbid conditions in diabetic patients have the potential to improve outcomes.
3. Both hypo and hyperglycemia is associated with worse outcomes and increased LOS. There is a general consensus that the target perioperative glucose zone is from 6-10 mmol/L. Among Type 1 diabetics, basal insulin should be continued (albeit at a reduced dose) in order to minimize the risk of hospital acquired DKA (which accounts for 8% of all DKA cases).
4. Diabetic patients require a meticulous assessment by pre-operative staff familiar with diabetes management. There needs to be effective communication with the patient and ward staff on the exact perioperative diabetes management plan. Diabetes medications should be prescribed in the pre-assessment clinic – same with medications for dealing with hyper/hypoglycemia.
5. ERAS has proven better outcomes when there is a standardised surgical pathway that begins with the primary care referral – this is no different for diabetes. All diabetics should have an HbA1c completed and document within 3 months before elective surgery, bearing in mind that it takes 3 months to optimise a diabetic patient. Use the diabetes care team when in doubt. The identification of a poorly controlled or previously undiagnosed diabetic in the pre-op clinic just before elective surgery should no longer be an acceptable standard of care.