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).