Blood glucose control during cardiac surgery: an evaluation of a fixed versus a variable insulin regime

Introduction

Intensive insulin therapy (blood glucose < 6.1 mmol/l) may reduce mortality after cardiac surgery (by 42%) [1]. An effective regime would keep blood glucose < 6 mmol/l for 80% of the time; < 8 for 90% of the time and <12 for 99% of the time, and no hypos (< 3.0).

Method

Ninety elective heart surgery patients were recruited, and randomly allocated a 'Fixed' regimen (F) (Table 1) or a 'Variable' regimen (V) (Table 2) (n = 45). Blood sugars were recorded 1–2 hourly postoperatively for 48 hours. In each patient the mean and standard deviation were calculated. Episodes of hypoglycaemia (< 3 mmol/l), and mild (6.1–8.0), moderate (8.1–12) or severe (>12) hyperglycaemia were identified.

Table 1 (abstract P379)

Table 2 (abstract P379)

Results and conclusion

The variable better controlled blood glucose (V = 6.5 ± 0.74; F = 7.0 ± 0.90) (P = 0.004) especially in patients with a high BMI (> 25) (Fig. 1). There were more hypos in F (n = 4) than V (n = 1). Glucose < 6 mmol/l was found for 33% of the time in F, 48% in V; < 8 mmol/l for 75% in F and 82% in V; <12 mmol/l for 99% in F and 99% in V.

Figure 1

(abstract P379)