Analgesia and sedation for ventilated newborn infants of low dose remifentanyl infusion

Introduction

The aim of our study is to verify the usefulness of remifentanyl (R) in ventilated newborn (nw) evaluating the analgesic effect and how variation of R infusion maintains a level of analgesia according to different modality of ventilation (MV).

Materials and methods

Eighteen nw were admitted in ICU for RDS, GA > 32, mean weight 2.250 ± 450 g. A modified scale, according to PIPP and Comfort, was used to evaluate 'comfort'. According to the score (S) all patients were divided in three groups: A < 5; B = 5; C > 5. Data were collected at T0 (basal value), T1 (30 min after start infusion), Tn (every 4 hours), T-est (extubation time), and T post-est (30 min after extubation). R infusion was started at 0.25 µg/kg/min to obtain an 'ideal' S 5 ± 1; and was modified to obtain an adequate analgesia during PCV. After 'critical' phase R was reduced, evaluating the mean t to reach an adequate RD (respiratory drive) for weaning. S at this moment was < 5 (max 7). Finally R was stopped and the mean t for extubation was calculated. For all parameters median value and SD were calculated. For HR, BP, PSO₂ in A, B, C a Student t test was adopted for the significance (P < 0.005) through the single value at T0 (T0 vs A, T0 vs B, T0 vs C) and also A, B, C (A vs B, A vs C, B vs C).

Results

The mean t of R (T1-Tstop) was 66.94 ± 22 hours, with a mean dose of R 0.146 ± 0.038 µg/kg/min. The mean t to reach comfort (5 ± 1) was 20 ± 13.11 hours (T1-T5) with R 0.17 ± 0.14 µg/kg/min. R was 0.18 ± 0.04 µg/kg/min in PCV with a S of 4 ± 0.63. The mean t, to obtain a RD to change PCV to PAV, was 2.30 ± 0.56 hours with R 0.09 ± 0.04 µg/kg/min, comfort S 5 ± 0.53 referred to all the period of PAV. Stop-Test was 15 ± 3.4 min. The S at Tpost-est was 5.5 ± 1.03. Statistically significant is the fall of HR at T0 vs A (P = 0.003) and T0 vs B (P = 0.002) as a confirmation that an adequate level of analgesia brings a stabilization of hemodynamic changes to pain stimuli. SpO₂ increased from T0 vs A (P = 0.005) and T0 vs B (P = 0.001) due to synchronization of the patients to MV since the good level of analgesia was reached.

Conclusion

No adverse effects were observed: low dose of R maintained an analgesia with an assessment of patients to MV. Infusion t did not influence time of extubation. Although the S 5 ± 1 is an hypothetic 'ideal' level of analgesia, we can assess that R could permit, in newborn, to reach a state of comfort during all 'MV therapy' until extubation, when pain stimulus is removed.