Haemodynamic effects of remifentanil in children with and without intravenous atropine. An echocardiographic study

Abstract

Background: Remifentanil is known to cause bradycardia and hypotension. We aimed to characterize the haemodynamic profile of remifentanil during sevoflurane anaesthesia in children with or without atropine.

Methods: Forty children who required elective surgery received inhalational induction of anaesthesia using 8% sevoflurane. They were allocated randomly to receive either atropine, 20 microg kg(-1) (atropine group) or Ringer's lactate (control group) after 10 min of steady-state 1 MAC sevoflurane anaesthesia (baseline). Three minutes later (T0), all children received remifentanil 1 microg kg(-1) injected over a 60 s period, followed by an infusion of 0.25 microg kg(-1) min(-1) for 10 min then 0.5 microg kg(-1) min(-1) for 10 min. Haemodynamic variables and echocardiographic data were determined at baseline, T0, T5, T10, T15 and T20 min.

Results: Remifentanil caused a significant decrease in heart rate compared with the T0 value, which was greater at T20 than T10 in the two groups: however, the values at T10 and T20 were not significantly different from baseline in the atropine group. In comparison with T0, there was a significant fall in blood pressure in the two groups. Remifentanil caused a significant decrease in the cardiac index with or without atropine. Remifentanil did not cause variation in stroke volume (SV). In both groups, a significant increase in systemic vascular resistance occurred after administration of remifentanil. Contractility decreased significantly in the two groups, but this decrease remained moderate (between -2 and +2 sd).

Conclusion: Remifentanil produced a fall in blood pressure and cardiac index, mainly as a result of a fall in heart rate. Although atropine was able to reduce the fall in heart rate, it did not completely prevent the reduction in cardiac index.

Fig. 1

Heart rate (beats min⁻¹) values under remifentanil compared with 1 MAC sevoflurane steady-state values (baseline). T0=time after injection of atropine (AT) or Ringer (RL); time (min) 5 and 10 under remifentanil at 0.25 μg kg⁻¹ min⁻¹; time 15 and 20 under remifentanil at 0.5 μg kg⁻¹ min⁻¹. Vs baseline, ^*P<0.05; vs T0, ^‡P<0.05; vs T10, ^$P<0.05. Open circles correspond to minimum and maximum values.

Fig. 2

Cardiac index values under remifentanil compared with 1 MAC sevoflurane steady-state values (baseline). T0=time after injection of atropine (AT) or Ringer (RL); time (min) 5 and 10 under remifentanil at 0.25 μg kg⁻¹ min⁻¹; time 15 and 20 under remifentanil at 0.5 μg kg⁻¹ min⁻¹. Vs baseline, ^*P<0.05; vs T0, ^‡P<0.05; vs T10, ^$P<0.05. Open circles correspond to minimum and maximum values.

Fig. 3

Contractility values (stress–velocity index, SVI) under remifentanil compared with 1 MAC sevoflurane steady-state values (baseline). T0=time after injection of atropine (AT) or Ringer (RL); time (min) 5 and 10 under remifentanil at 0.25 μg kg⁻¹ min⁻¹; time 15 and 20 under remifentanil at 0.5 μg kg⁻¹ min⁻¹. Vs baseline, ^*P<0.05; vs T0, ^‡P<0.05; vs T10, ^$P<0.05. Open circles correspond to minimum and maximum values.