Results
A total of 125 infants were seen in pulmonary clinic for home oxygen management after NICU discharge; 71 infants were discharged from our NICU and 54 infants were referred from local NICUs. Of the 125 infants, 123 had complete 1 year follow up. Diuretics were used at NICU discharge in 78 (62%) infants. Common medications included spironolactone/hydrochlorothiazide (53), chlorothiazide (11) and hydrochlorothiazide (14).
Active diuretic weaning was used in 52 infants; the median time to discontinuing diuretics for actively weaned infants was 12 weeks after NICU discharge (IQR 9-17 weeks). Passive weaning was used in 19 infants, with 12 who were passively weaned because they failed initial room air trial and 7 who were passively weaned for other etiologies. Their median time to discontinuing diuretics was 16 weeks after NICU discharge (IQR 14-21, p=0.025 compared to active weaning). An additional 7 infants were passively weaned due to secondary medical reasons including pulmonary hypertension (3), pulmonary vein stenosis (1), PDA (1) and recurrent hospitalization (2). These 7 infants were dropped from subsequent comparisons.
Illness characteristics of infants in diuretic weaning groups are displayed in Table 1. Compared to infants discharged without diuretics, infants discharged with actively-weaned diuretics were born at an earlier gestational age; received more surfactant, and days on mechanical ventilation; were discharged at a later corrected gestational age and with higher liter flow of home oxygen. After discharge, they were at higher risk for readmissions. There were fewer illness differences between infants actively versus passively weaned from diuretics. Notably, there were no significant differences between the three groups in family history of asthma or discharge with inhaled corticosteroids; after NICU discharge.
Figure 2 shows the primary outcome of duration of home oxygen. Actively weaning diuretics was not associated with longer duration of home oxygen compared to infants who were never discharged on diuretics. Passively weaned infants spent the most time on home oxygen. Table 2 shows differences in secondary outcomes related to home oxygen weaning. Compared to infants discharged without diuretics, infants with actively-weaned diuretics had more failed overnight pulse oximetry studies, but without differences in sleep studies done, number of clinic visits, missed appointments, or off protocol weaning attempts. Passive weaning of diuretics was more likely to be recommended for infants who failed room air trials in clinic. Seventy eight percent of infants on diuretics had their diuretics discontinued prior to the discontinuation of home oxygen (75% of those who were actively weaned; 25% of those who were passively weaned).
Table 3 shows associations between duration of home oxygen therapy and other illness characteristics in addition to diuretic weaning strategy. Longer duration of home oxygen was associated with lower birth weight, PDA ligation, more days of mechanical ventilation and higher liter flow of home oxygen at NICU discharge. After NICU discharge, longer duration of home oxygen was associated with use of inhaled and systemic corticosteroids, respiratory readmissions, and emergency department visits. Off protocol weaning of home oxygen therapy was also associated with longer duration of home oxygen. In multivariable regression analysis, passively-weaned diuretics were associated with longer duration of home oxygen therapy, adjusted for NICU and post-discharge illness characteristics. Other significant associations with home oxygen duration included post-discharge inhaled corticosteroids and infants who had their home oxygen weaned off-protocol (Table 4).