Anaesthesia

CASE 94: FitneSS For Surgery – patientS With DiabeteS

history

You are the surgical doctor in the pre-assessment clinic and you are asked to review a 56-year- old man who is due to have a transurethral resection of a bladder tumour (TURBT). He has non-insulin-dependent diabetes and had a myocardial infarction 7 years ago. His current medications include metformin 500 mg bd, gliclazide 80 mg od, aspirin 75 mg od, lisinopril 20 mg od and gaviscon prn. He has no known allergies. He gave up smoking after his myocardial infarction.

examination

Observations are normal. The patient appears comfortable. Heart sounds are normal and the chest is clear. The abdomen is soft, non-tender and the genitalia are normal.

Questions

•Which investigations would be appropriate prior to his surgery?

•What types of complications commonly affect patients with diabetes?

•Where should the patient be placed on the operating list?

•What regimen would you recommend for keeping good glycaemic control in the perioperative and postoperative period?

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100 Cases in Surgery

ANSWER 94

The patient should have a full blood count, urea and electrolytes, blood glucose and a haemoglobin A1c as an indicator of previous glycaemic control. When assessing patients with diabetes in pre-assessment, a full cardiovascular, respiratory, abdominal and neurological examination should be performed. The lower limbs should be examined for peripheral neuropathy and ulceration. The peripheral pulses should also be palpated for evidence of peripheral vascular disease. Fundoscopy should be carried out to assess the retina, and a blood pressure measurement should be recorded in both the lying and standing positions to assess for autonomic neuropathy. An electrocardiogram should be done to screen for cardiac disease.

Patients with diabetes have an increased risk of postoperative complications because of the presence of microvascular and macrovascular disease:

•Atherosclerosis: ischaemic heart disease/peripheral vascular disease/cerebrovascular disease

•Nephropathy: renal insufficiency

•Retinopathy: limited visual acuity

•Autonomic neuropathy: gastroparesis, decreased bladder tone

•Peripheral neuropathy: lower-extremity ulceration, infection, gangrene

•Poor wound healing

•Increased risk of infection

Tight glycaemic control (6–10 mmol/L) and the prevention of hypoglycaemia are critical in preventing perioperative and postoperative complications. The patient with diabetes should be placed first on the operating list to avoid prolonged fasting. For patients with insulindependent diabetes, a ‘sliding scale’ regimen of insulin is given at a particular rate according to the blood glucose. Patients with diet-controlled diabetes who are undergoing minor surgery need no specific treatment. Those undergoing minor surgery whose diabetes is controlled with oral hypoglycaemic agents should omit their medication prior to surgery to prevent hypoglycaemia or lactic acidosis. They should recommence once they are eating and drinking properly after their surgery. Those who are having major surgery but are expected to be able to eat and drink relatively soon postoperatively can have a trial of omitting their medication on the morning of surgery and close blood glucose monitoring. If the blood glucose is greater than 12 mmol/L prior to surgery, or where feeding is not likely to start soon after surgery, a ‘sliding scale’ insulin regimen should be instigated. Some patients will be taking chlorpropramide, a long-acting sulfonylurea for diabetic control. This should be stopped 48 h prior to surgery to prevent hypoglycaemia in the perioperative and postoperative period.

KEY POINTS

•insulin-dependent patients should be placed on a sliding scale prior to fasting.

•oral hypoglycaemic agents should be stopped prior to surgery.

•patients with diabetes have an increased risk of postoperative complications.

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