27. Diabetes: peri-operative management

Question 1

An elderly patient with IDDM is scheduled for an axillo-femoral bypass graft.

What are the important features of a pre-operative assessment in diabetic patients?

Answer 1

Glycaemic control
It is important to get a feel for the patient’s recent diabetic control,
assessing glucose control as well as hydration and acid–base balance.

Current hypoglycaemic agents should be reviewed.

The patient will undergo a period of starvation as well as a
surge of catabolic hormone secretion associated
with the stress response to surgery.

Tight control of blood glucose has both short- and long-term advantages.
In the acute setting inadequately treated diabetes can cause symptomatic
hypoglycaemic episodes or severe dehydration with acidosis (lactic and/or
ketoacids). Raised blood sugar levels peri-operatively have been linked with
wound infection and poor neurological outcome in cardiac surgery.

In the longer term, improved glucose control can reduce the
microvascular and neuropathic complications of this disease.

Question 2

Assessment of diabetic complications

Answer 2

Coronary artery disease
Autonomic neuropathy
Diabetic nephropathy
Respiratory changes/airway assessment
Associated endocrine disorders

Question 3

Are these complications of diabetes of concern to you as an anaesthetist?

Answer 3

Diabetics are four to five times as likely to have coronary heart disease as
non-diabetics and a proportion of these are asymptomatic.

Autonomic neuropathy occurs in up to 40% of type 1 diabetics
and can take the form of
postural hypotension,
gastroparesis,
diarrhoea and
bladder paresis.

There can be unexpected tachycardia, arrhythmias and hypotension
(often unresponsive to atropine and ephedrine).

Diabetics with autonomic neuropathy show increased QT variability
(i.e. regional variations in ventricular recovery)
and this may be a major factor in the ‘sudden death
syndrome’ recognized in this group.

Gastroparesis causes an increase in the volume of gastric contents with increased risk of aspiration. The degree of autonomic neuropathy is difficult to quantify pre-operatively,

but the Valsalva manoeuvre and assessment of heart rate variability may be of
benefit.

Question 4

Diabetic nephropathy

Answer 4

Diabetic nephropathy

increases the risk of peri-operative renal failure and infection.

Appropriate fluid and haemodynamic monitoring is essential

Question 5

Respiratory

Answer 5

: diabetes is associated with a reduced FEV1 and FVC.

It has been estimated that 30%–40% of long-standing diabetics develop the ‘stiff joint
syndrome’ in which chronically raised blood sugar levels cause protein
glycosylation and reduced elasticity of connective tissues.

This is associated with poor neck extension and mouth opening and a higher incidence of
difficult intubation.

Question 6

How would you manage this man’s glucose control peri-operatively?

Answer 6

This is an elderly man who is insulin dependent undergoing a major surgical
procedure. The main principles are:

Regular blood glucose monitoring.

Insulin and glucose infusions during the period of starvation

There are many methods of providing continuous insulin/glucose infusions and
hospital policy may dictate the regimen chosen

Question 7

. The two main regimens are:

Answer 7

1. Separate infusions of insulin and glucose – the insulin rate is adjusted
   according to the blood glucose level.
2. The Alberti regimen provides glucose, insulin and potassium in the same
   solution, thus eliminating the potential for giving insulin without glucose
   or vice versa.

As indicated above, these regimens should be commenced and stabilised
pre-operatively and continued until the patient has resumed eating/drinking
and their normal hypoglycaemic agents.

Question 8

What is your preferred anaesthetic technique in this man?

Answer 8

This man requires a general anaesthetic and,

if gastric stasis is suspected, then a rapid sequence
induction is the technique of choice. In an elderly man with
known vascular disease,

an arterial line inserted pre-induction would be prudent,

especially if there is a question of autonomic neuropathy.

A high-dose opiate anaesthetic technique will reduce
the sympathetic and hormonal response to surgery,
providing both metabolic and haemodynamic stability