Peri-op care - Steroids

Question 1

What is impact of surgery on ACTH and cortisol levels?

Answer 1

Surgery is one of most potent activators of ACTH and cortisol secretion (stress causes increased secretion of pituitary hormones).

The usual feedback mechanism (where increased plasma cortisol inhibits further secretion of ACTH) appears ineffective after surgery so that the concs. of both hormones remain high.

Question 2

What is the effect of increased cortisol on metabolism during surgery?

Answer 2

1. Hyperglycaemia: increased hepatic glycogenolysis and gluconeogenesis, and decreased peripheral use of glucose.
2. Protein catabolism to amino acids for use as energy or by liver to form new proteins, e.g. acute-phase proteins.
3. Triglyceride conversion to glycerol and fatty acids by lipolysis - becomes major source of energy.

Question 3

Why must exogenous steroid use not be stopped suddenly? Who is most at risk of this complication?

Answer 3

Exogenous steroids can cause hypothalamo-pituitary adrenal axis suppression if stopped suddenly, i.e. adrenal insufficiency.

Those most at risk are those receiving high doses (>20-30mg prednisolone or equivalent) of systemic steroids for long periods (>3wks) and those who appear to have Cushingoid features.

Question 4

What is the effect of surgery in a patient on oral steroids that have not been adequately replaced?

Answer 4

Surgical patients are nil by mouth so cannot take their oral steroids.

Stresses of surgery can cause post-op cardiovascular collapse with hypotension and shock - Addisonian crisis.

Question 5

Describe the symptoms of an addisonian crisis.

Answer 5

• malaise
• fatigue
• abdo pain, nausea and vomiting
• low-grade fever
• muscle cramps and pains

These are followed by dehydration, leading to hypotension and hypovolaemic shock. There may be confusion, loss of consciousness and coma.

Question 6

Describe the findings of a blood test during an adrenal crisis. What test is diagnostic?

Answer 6

‘Typical’ biochemical profile (intravascular volume depletion):

• hyponataemia
• hyperkalaemia
• raised urea

Synacthen test is diagnostic (synthetic ACTH analogue that normally increases plasma cortisol),

Question 7

How should surgical patients with potential adrenal insufficiency be managed during peri-operative period?

Answer 7

Must be given steroid cover during peri-op period, usually IV hydrocortisone (e.g. 25-50mg prior to op and 50mg daily until recovery)