Diabetes mellitus

Regarding the anaesthetic considerations of patients with diabetes mellitus, the following

are correct EXCEPT which one?

a) The National Institute of Health and Clinical Excellence recommends preoperative

urinalysis for ASA 2 patients with cardiovascular comorbidity

b) The Alberti regime initially involves 500mL of 10% dextrose with 10 mmol of

potassium chloride and 10 units of rapid acting soluble insulin infused at 100mL/h

c) Patients with diabetes are prone to gastroparesis and thus pulmonary aspiration of

gastric contents

d) Glycosylation of collagen in cervical and temporomandibular joints may render

laryngoscopy difficult

e) Autonomic dysfunction is detectable in 40% of patients with diabetes mellitus Type 1

Answer: a

Explanation

Options (c) and (d) are well known facts and should be considered in clinical practice

and quoted in viva responses regarding the challenges that face the anaesthetist in the

peri-operative management of the patient with diabetes. Similarly the Alberti regime is

something to be learned and should not trip up the informed candidate in this case.

This leaves (a) and (e), which might be the correct answers. A candidate may scour

endocrinology texts to confirm or refute the value of 40% in (e); however, examiners are

well aware that different sources will quote a variety of values but that these will likely

be in a range about a mean. In cases such as these, if the branch is false, it is likely to be

so by an order of magnitude (e.g. 4%) or at least double or half (80% or 20%) in order to

acknowledge that sources vary. If the value appears to be close to the one the candidate

has learned (or even sounds sensible) it is more than likely to be true because if it were

false it would be very false.

By exclusion, therefore, this leaves (a) as the correct answer. It seems intuitive good

practice to perform urinalysis for glucose, protein and ketones in a preoperative

patient with diabetes. In the extensive document published by NICE in June 2003

there is no specific mention of this. Authorities involved in compiling the recommendations

did not reach consensus on the value of preoperative urinalysis. This answer

can be reached by exclusion without memorising the content of the NICE guidelines;

however, it would be worth the candidate having an overview of the recommendations

and in particular those that seem counterintuitive.

Reference

National Collaborating Centre for Acute Care. Preoperative tests. The use of

routine preoperative tests for elective surgery. Evidence, methods and guidance.

NHS/NICE, June 2003. Online at www.nice.org.uk/nicemedia/pdf/Preop_Fullguid

eline.pdf (Accessed 30 October 2009)