The influence of remifentanil and remifentanil-plus-sevoflurane-controlled hypotension on mean arterial pressure and heart rate in children.

UNLABELLED

The aim of the study is to determine the influence of remifentanil and remifentanil-plus-sevoflurane-induced anaesthesia on mean arterial pressure and heart-rate during controlled hypotension in children and to evaluate the quality of the operative field.

METHODS

30 children, ASA I physical status were scheduled for middle ear microsurgery for cochlear implantation and divided into 2 groups: R group (15 children who received remifentanil as a hypotensive agent during general anaesthesia). R + S group (15 children who received remifentanil and sevoflurane as hypo-tensive agents together to reach the hypotensive level during general anaesthesia). The hypotensive level was defined as 20% decrease of baseline MAP. We used oral medication for sedation (1 mg/kg Flormidal), 10 mg/kg parace-tamol rectally for postoperative analgesia. Two variables were measured during the anaaesthesia: MAP and HR at five time intervals. We also measured the duration of hypotension, the time to reach a hypotensive level and the duration of anaesthesia and surgery (inmins). The quality of the surgical field in terms of dryness was rated every ten minutes by the surgeon who used a six-point scale, 0-5 scale (0=no bleeding, visually bloodless field; 5=uncontrolled bleeding).

RESULTS

Demographic analyses showed that 13 of the patients were female, 17 of them were male, with an age-range of 4.75±3.2 years in the R group of patients and 3.5±4.1 in the R+S group of patients. Duration of hypotension was 135±4 minutes (R) and 120±3 minutes (R+S). Duration of anaesthesia was 160±10 minutes (R) and 140±9 minutes (R+S). The duration of surgery was 150±5 minutes (R) and 130±4 minutes (R+S). The time to reach hypotensive level was shorter in R+S group (5±1 minutes) than R group (7±6 minutes). There was no statistically significant difference in MAP values measured at T1, T2, T3 and T4 time intervals between the two groups of patients (R and R+S group). We achieved hypotensive anaesthesia levels of MAP in both group of patients. The influence of anesthesia on HR was analysed at the same time intervals. In T2 time interval (30 minutes after the induction of anaesthesia), HR values in R group patients were statistically significantly higher than referent hypotensive values in the R+S group of patients (70-80 bpm). We could see the same result of HR values at T3 and T4 time intervals (90 and 120 minutes after the induction) in R group patients compared with HR values in the R+S group. We achieved a hypotensive level of HR (70-80 bpm) only at R+S group of patients, which means that remifentanil in combination with sevoflurane is an excellent combination for maintaining hypotension during general anaesthesia. The lowest hypotensive level of HR was measured 120 minutes after the induction of anaesthesia in the R+S group of patients (69 bpm). Remifentanil and remifentanil in combination with sevoflurane are effective in inducing consistent and sustained controlled hypotension in children undergoing middle ear microsurgery.