Effect of Administering Low-Dose Fentanyl Infusion on Respiratory Dynamics in the Premature Ventilated for Respiratory Distress Syndrome-A Randomized Double-Blind Trial

Abstract

AIM:Of this work was to assess the respiratory dynamics in preterm infants ventilated for RDS under continous infusion of low-dose Fentanyl. METHODS:The study included all preterm (>28 week of gestation) with RDS and conventionally ventilated at the NICU of Padua Pediatrics Department between May '97 and October '98. After obtaining the informed consent of parents, patients were randomized in double-blind trial to receive Fentanyl in continous venous infusion 1.5 µg/kg/h, scaled down by 0.5 µg/kg/h every 24 hours, for a total 72 hours of infusion or a placebo infusion of 5% glucose solution. At the baseline and every 24 hours after starting the trial, all ventilation parameters were recorded on the Babylog 8000 (Peak Inspiratory Pressure (PI), Respiratory Rate (RR), Tidal Volume (TV) and Minute Ventilation (MV)), along with arterial blood gas (ABG) findings and electromyographic activity (µVolt) of the intercostal muscles recorded by means of skin electrodes applied to the chest and data logging on Modulab SATEM series 800 interfaced with a computer. A sedation score was also attributed every 4 hours.RESULTS:The study involved 27 premature infants, 13 treated with Fentanyl (F) and 14 with the placebo (C). The two groups were comparable in terms of: BW 1400±404, GA30±2, Apgar at 1°6±2 and at 5°7±2, CRIB score 3±2. The two groups were also comparable in terms of the severity of their respiratory disorder, radiological score and need for surfactant therapy, duration of ventilation (F 5±1 vs C 5±4 days) and oxygen dependence (F 11±13 vs C 15±22 days), and hospital stay (F 41±20 vs C 41±25 days). No significant differences were found in the ventilating parameters (PI, RR, TV, MV) needed to maintain balanced ABG values. Spontaneous respiratory activity (%) tended to decline significantly in the group on Fentanyl, especially in the first 24-48 hours of infusion: spontaneous respiratory activity (%) at baseline F 37±18 vs C 36±28, at 24 h F 14±9 vs C 52±26 (p < 0.05), at 48 h F 19±21 vs C 61±33 (p <0.05), at 72 h F 41±35 vs C 54±38, at 96 h F 58±39 vs C 66±35. Electromyographic activity revealed no significant differences, however. Moreover, the group treated with Fentanyl showed a better sedation score than controls.CONCLUSION:The use of low-dose Fentanyl in preterm infants with RDS is effective in making the child more comfortable, without inducing significant side effects on respiratory dynamics during ventilation, but nonetheless significantly reduces spontaneous respiratory activity, even at doses of 1-1.5 µg/kg/h. The results prompt caution in the use of the drug even at low doses in patients whose spontaneous respiratory activity is desirable while under ventilation.