Peri-operative care

Assessing fitness for surgery

The main issue is usually assessing cardio-respiratory fitness in a breathless patient. Generally, if the patient can walk around the ward, he or she can probably cope with a modern anaesthetic. Multiple different scoring tools are available with varying degrees of complexity and utility.¹ The SORT score is probably one of the simpler ones.² For the calculator go to: http://www.sortsurgery.com/

If you are still not sure, and the procedure is elective, try optimising anti-failure and bronchodilator therapy (if appropriate) and then re-assessing. If the procedure is not elective, then the decision is not about suitability for anaesthesia, but about prognosis with and without surgery.

Perspective – fitness for thoracic surgery

Although FEV1 with various cut-points in terms of percentage deviation from expected normal for that patient’s height and weight traditionally has been used for predicting post-operative complications, an equally simple test may fare better – a drop by more than 4% points in sats with oximetry after exercise (equivalent to climbing three flights of stairs) is strongly predictive of increased ICU stay post-operatively¹.

Perspective – predicting who might need post-operative ventilation in non-thoracic surgery.

A systematic review² aimed at identifying post-operative problems identified some factors of use (predictive of post-op hypoxaemia or need for ventilation). Most of the information is from single studies. A previous diagnosis of COPD is highly specific (96%, LR+ 4.5) but insensitive at 18%, LR- 0.75). Pre-op sputum production is more sensitive (56%) and relatively specific (75%, LR+ 2.2, LR- 0.59.) Upper abdominal surgery and the need, at surgery, to place a naso-gastric tube are also both moderately useful features (LR+ 4.6 for the former and 5.1 for the latter.)

The patient who won’t wake up

• When was the last dose of opiate given in theatre, and how much was given?
• Adequate reversal of muscle paralysis? Perhaps repeat the neostigmine if in doubt.
• Check the finger-prick glucose.
• Body temperature? (beware of profound hypothermia – check with a low-reading thermometer if in doubt).
• Any new focal neurology to suggest a cerebral infarct or haemorrhage?
• How awake was he or she preoperatively?

Perspective – opiates and respiratory depression

Although opiates are generally safe in otherwise healthy patients experiencing severe pain, individuals do vary in their sensitivities to these agents, and ‘effect site’ levels may lag some time behind plasma clearance. “Topping up” analgesia post-op when opiates were already given only an hour or so previously in theatre may lead to dangerous respiratory depression, particularly if cumulative doses of more than the recommended dose of 0.15 to 0.2 mg/kg of morphine are given within a short period³.

Cardiac rhythm disorders in the peri-operative period

The most common cause for concern is the patient who appeared well and then developed multiple ventricular ectopics before surgery/anaesthesia. Surgery in such patients is cancelled and then a referral is written. A common scenario is inadequate or no pre-medication and a particularly nervous patient, and the cure is not an anti-arrhythmic but adequate and timeous pre-medication.

Other issues concern atrial tachyarrhythmias (atrial fibrillation, atrial flutter and various SVTs), which again may be worsened by nervousness (although usually not caused by it!) Check that the patient is adequately hydrated – 200 ml of saline may restore sinus rhythm and allow the surgery to continue.

1. Stones J, Yates D. Clinical risk assessment tool in anaesthesia. BJA Education 2019;19(2):47–53. ↩

2. Protopapa KL, Simpson JC, Smith NC, Moonesinghe SR. Development and validation of the Surgical Outcome Risk Tool SORT, British Journal of Surgery 2014;101(13)1774–17783 . https://doi.org/10.1002/bjs.9638.  ↩