[Inhalation therapy with nitric oxide in pulmonary hypertension: Comparison of preterm infants versus newborn infants].

BACKGROUND

Inhaled nitric oxide (iNO) is used as a vasodilator in pulmonary hypertension (PH) of the newborn infant.

PATIENTS AND METHODS

Retrospective analysis of patients, who were treated at our department with iNO in the period from 1994-2001. Response was defined as an increase of the paO (2)/FiO (2) Ratio > or = 20 % and/or a decrease of the oxygenation index (OI) >/= 20 % after 2 h (early response), and consecutively after 24 h (late response). The patients were divided into a) primary persistent pulmonary hypertension of the newbom (PPHN), or b) pulmonary hypertension secondary to meconium aspiration syndrome (MAS), sepsis or congenital diaphragmatic hernia (CDH).

RESULTS

Between 1994 and 2001 we treated 47 patients with iNO at our neonatal intensive care unit. We included 16 (35 %) preterm infants (GA 34,5 [25 - 37] weeks, GG 2061 [680 - 3410] g) (Median/Range) and 31 (65 %) newbom (GA 40 [38 - 42] weeks, GG 3510 [2550 - 4560] g). 18 (38 %) patients suffered from primary PPHN, 29 (62 %) from secondary PPHN (14 MAS [30 %], 8 sepsis [17 %], 4 CDH [8 %]). 8 (50 %) preterm and 20 (64 %) term infants showed a positive iNO response after 2 h, again 8 (50 %) preterm and 20 (64%) term infants showed a positive iNO response after 24 h. There was neither a significant difference between term and preterm infants at 2 h, nor at 24 h. Between 2 h and 24 h 10 patients changed in their response to iNO. 5 (18 %) patients with early response showed a significant degradation after 24 h, whereas 5 (26 %) of the patients without early response showed a significant improvement of the oxygenation alter 24 h. Alltogether 13 (72 %) patients with PPHN, 8 (57 %) with MAS, 2 (50 %) with CDH, 4 (50 %) with sepsis showed a positive iNO response after 24 h. In regard to the oxygenation parameters at start of iNO-therapy, the patients with early response did not differ from the patient without response (median OI: 20,0 versus 21,8, median paO (2)/FiO (2) Ratio: 59,3 versus 55,0 mmHg at the start of the iNO therapy).

CONCLUSION

In regard to iNO response, there was no significant difference between term and preterm infants. Due to the changing response, a positive iNO-response after 2 h had no predictive value for the further prognosis of the oxygenation situation under iNO therapy.