Nasal High-Flow Therapy for Newborn Infants in Special Care Nurseries

BACKGROUND

Nasal high-flow therapy is an alternative to nasal continuous positive airway pressure (CPAP) as a means of respiratory support for newborn infants. The efficacy of high-flow therapy in nontertiary special care nurseries is unknown.

METHODS

We performed a multicenter, randomized, noninferiority trial involving newborn infants (<24 hours of age; gestational age, ≥31 weeks) in special care nurseries in Australia. Newborn infants with respiratory distress and a birth weight of at least 1200 g were assigned to treatment with either high-flow therapy or CPAP. The primary outcome was treatment failure within 72 hours after randomization. Infants in whom high-flow therapy failed could receive CPAP. Noninferiority was determined by calculating the absolute difference in the risk of the primary outcome, with a noninferiority margin of 10 percentage points.

RESULTS

A total of 754 infants (mean gestational age, 36.9 weeks, and mean birth weight, 2909 g) were included in the primary intention-to-treat analysis. Treatment failure occurred in 78 of 381 infants (20.5%) in the high-flow group and in 38 of 373 infants (10.2%) in the CPAP group (risk difference, 10.3 percentage points; 95% confidence interval [CI], 5.2 to 15.4). In a secondary per-protocol analysis, treatment failure occurred in 49 of 339 infants (14.5%) in the high-flow group and in 27 of 338 infants (8.0%) in the CPAP group (risk difference, 6.5 percentage points; 95% CI, 1.7 to 11.2). The incidences of mechanical ventilation, transfer to a tertiary neonatal intensive care unit, and adverse events did not differ significantly between the groups.

CONCLUSIONS

Nasal high-flow therapy was not shown to be noninferior to CPAP and resulted in a significantly higher incidence of treatment failure than CPAP when used in nontertiary special care nurseries as early respiratory support for newborn infants with respiratory distress. (Funded by the Australian National Health and Medical Research Council and Monash University; HUNTER Australian and New Zealand Clinical Trials Registry number, ACTRN12614001203640.).

Major vasodilator role for nitric oxide in the gastrointestinal circulation of the mid-gestation fetal lamb

As nitric oxide (NO) may be a particularly important vasodilator in early life, we investigated its role in the regulation of the gastrointestinal (GI) circulation at mid-gestation. Cardiac output and GI blood flow were measured by the radioactive microsphere technique in eight chronically instrumented and unanesthetized mid-gestation fetal sheep. Mean arterial pressure (MAP), heart rate, blood flow, oxygen delivery, and vascular resistance were determined before and after infusion of the specific NO synthase inhibitor, Nomega-nitro-L-arginine (L-NNA) at doses of 10 and 25 mg/kg. In response to L-NNA infusion, MAP increased (p < 0.01) and combined ventricular output decreased (p < 0.001). GI blood flow and oxygen delivery decreased and vascular resistance increased in the stomach and all segments of the small and large intestine (all p < 0.001). The greatest reduction in blood flow was in the small intestine (p < 0.01) and the basal differential pattern of small intestinal blood flow exceeding large intestinal flow was completely abolished. These changes were much greater than those previously described in late-gestation fetuses. Our results suggest that, at mid-gestation, NO plays a major role in the regulation of blood flow and vascular tone across all segments of the fetal GI tract, with its effects being more pronounced than later in development.

Impact of erythromycin on respiratory colonization of Ureaplasma urealyticum and the development of chronic lung disease in extremely low birth weight infants

BACKGROUND

Chronic lung disease (CLD) is a significant cause of neonatal morbidity and mortality despite advances in neonatal care. Ureaplasma urealyticum colonization of the lower respiratory tract has been associated with CLD, particularly in extremely low birth weight infants. Despite numerous studies demonstrating the pathogenicity of this organism, treatment remains controversial. This study examines neonates colonized with U. urealyticum in the lower respiratory tract and treated with erythromycin, as compared with noncolonized neonates.

METHODS

A prospective cohort study of 124 neonates weighing <1000 g at birth, requiring endotracheal intubation and ventilation. Endotracheal aspirates were cultured for U. urealyticum and conventional bacteria twice weekly for the duration of endotracheal intubation. Infants colonized with U. urealyticum were treated with intravenous erythromycin. Maximal ventilatory requirements, CLD at Day 28 and 36 weeks postconception, duration of ventilation, oxygen dependency and hospital stay were documented.

RESULTS

Twenty-two infants (18%) were identified as being U. urealyticum colonized in endotracheal aspirates. Colonization was significantly associated with younger maternal age, prolonged rupture of membranes, premature labor and vaginal delivery. Of colonized neonates 14% were delivered by cesarean section, with intact membranes. As compared with noncolonized infants, there were no statistically significant differences in chronic lung disease, duration of oxygen therapy or time to discharge.

CONCLUSIONS

Seven published cohort studies of similar high risk populations where U. urealyticum-colonized infants did not receive erythromycin therapy, show a consistent association with CLD (pooled relative risk + 5.21; 95% confidence interval, 2.93 to 9.64). This association was not demonstrated in the current study and adds further weight to the need for a randomized controlled trial to be performed to evaluate this treatment regimen.

Nitric oxide modulates regional blood flow differences in the fetal gastrointestinal tract

We studied the role of endogenous nitric oxide (NO) in the regulation of gastrointestinal (GI) circulation in 11 chronically instrumented and unanesthetized late-gestation fetal sheep. Systemic and GI blood flows were measured by the radiolabeled microsphere technique. Mean arterial pressure (MAP), heart rate, blood flows, oxygen delivery, and vascular resistance were determined before and after infusion of the specific NO synthase inhibitor, N omega-nitro-L-arginine (L-NNA), to cumulative doses of 10 and 25 mg/kg. At both L-NNA doses, MAP increased, and combined ventricular output and heart rate decreased. GI blood flow and oxygen delivery decreased and vascular resistance increased for the stomach, all segments of the small intestine, and proximal colon and cecum but were unchanged in the middle and distal colon and rectum. Because blood flow reduction in the small intestine was pronounced (from 176 to 107 ml.min-1.100 g-1, P < 0.001) and blood flow in the large intestine was unchanged, distribution of intestinal blood flow became more uniform. Overall, blood flow reduction was proportionally greater in GI circulation than in the remainder of fetal circulation. In three additional animals we established that L-NNA reduced blood flow to the mucosal-submucosal layer (P < 0.02) but not to the muscularis serosa of the small intestine. In the same animals, L-arginine (250 mg/kg) restored systemic hemodynamics and partially restored small intestinal blood flow. Our results suggest that NO is an important differential regulator of vascular tone in the developing GI circulation.