Hyperglycemia can occur in patients undergoing cardiac surgery even when glucose homeostasis has been normal in the preoperative period.1-3 Morbidity and mortality have been shown to be reduced in these patients following tight control of blood glucose levels using insulin therapy in the perioperative period.3

A survey was conducted

  • To find out protocols used in cardiac surgery intensive care units (ICUs) to control blood glucose.

  • To find the range of blood glucose and K+ levels in these units.


In this survey, data were collected over telephone from the sister-in-charge and/or the ICU registrar of 36 cardiac surgical ICUs in the United Kingdom (Graph 1). The data included types and number of cases, range of blood glucose levels in ICU patients, insulin protocol for control of blood glucose, maintenance fluid, and range of K+ (Graphs 2 to 4).


  • Extended sliding scale: Fixed-dose sliding scales used in the general wards extended into the cardiac ICUs (no bolus)

  • Complex sliding scales: Bolus and infusion of insulin as per sliding scale

  • Dynamic insulin protocol: Nurse-led tight glucose control based on a separate protocol (Graph 5).

The centers contacted were performing adult, pediatric, and transplantation surgeries with an average of 87 (50–100) cases a month. There were variations in the usage of insulin protocols. We categorized them as extended, complex, and dynamic scale (tight glucose control).

Graph 1

Average number of operations per month

Graph 2

Glucose range

Graph 3

Maintenance fluid

Graph 4

Range of potassium

Graph 5


Graph 6

Cardiac surgical centres


Two centers used dynamic scale insulin protocol and the rest had an insulin sliding scale protocol. It was observed that blood glucose was maintained between 4 and 8 mmol/L in the majority of the centers, with a few centers maintaining glucose below 10 mmol/L. The maintenance fluids used also varied, with a large number of centers using dextrose-based fluids. Potassium was maintained above 4.5 in the majority of the centers (Graph 6).


The in-hospital morbidity and mortality have been shown to be reduced by strict maintenance of normoglycemia.4 The tight control of blood glucose rather than higher insulin dose appears to protect against most ICU complications and death.3 Although all centers had protocols for glucose control, there were wide variations in insulin regime used and the range of blood glucose being maintained. The maintenance fluid used also varied. However, blood glucose was maintained below 8 mmol/L in majority of the centers.

Conflicts of interest

Source of support: Nil

Conflict of interest: None