Diaphragm electromyography results at different high flow nasal cannula flow rates.

Heated, humidified, high-flow nasal cannula (HHHFNC) is increasingly being used, but there is a paucity of evidence as to the optimum flow rates in prematurely born infants. We have determined the impact of three flow rates on the work of breathing (WOB) assessed by transcutaneous diaphragm electromyography (EMG) amplitude in infants with respiratory distress or bronchopulmonary dysplasia (BPD). Flow rates of 4, 6 and 8 L/min were delivered in random order. The mean amplitude of the EMG trace and mean area under the EMG curve (AEMGC) were calculated and the occurrence of bradycardias and desaturations recorded. Eighteen infants were studied with a median gestational age of 27.8 (range 23.9-33.5) weeks and postnatal age of 54 (range 3-122) days. The median flow rate prior to the study was 5 (range 3-8) L/min and the fraction of inspired oxygen (FiO2) was 0.29 (range 0.21-0.50). There were no significant differences between the mean amplitude of the diaphragm EMG and the AEGMC and the number of bradycardias or desaturations between the three flow rates.Conclusions: In infants with respiratory distress or BPD, there was no advantage of using high (8 L/min) compared with lower flow rates (4 or 6 L/min) during support by HHHFNC. What is known: • Humidified high flow nasal cannulae (HHHFNC) is increasingly being used as a non-invasive form of respiratory support for prematurely born infants. • There is a paucity of evidence regarding the optimum flow rate with 1 to 8 L/min being used. What is new: • We have assessed the work of breathing using the amplitude of the electromyogram of the diaphragm at three HHHFNC flow rates in infants with respiratory distress or BPD. • No significant differences were found in the EMG amplitude results or the numbers of bradycardias or desaturations at 4, 6 and 8 L/min.

Does Preterm Prolonged Rupture of Membranes Increase the Risk of Needing Invasive Respiratory Support? A Retrospective Single-Centre Study.

(1) Background: Preterm premature rupture of membranes (PPROM) has been associated with increased perinatal morbidity, but the effect of PPROM on respiratory disease has not been previously quantified. We hypothesised that PPROM would be associated with a higher incidence of invasive ventilation. (2) Methods: A retrospective cohort study at the Neonatal Unit at King's College Hospital NHS Foundation Trust, London, UK, was conducted on infants born before 37 weeks of gestation. PPROM was defined as the rupture of membranes for >48 h. (3) Results: We reviewed 1901 infants (434 with PPROM) with a median (IQR) gestational age of 32.4 (28.7-35.0) weeks. The median (IQR) duration of rupture of membranes in the infants with PPROM was 129 (78-293) h. The incidence of invasive ventilation was 56% in the infants with PPROM and 46% in the infants without PPROM (p < 0.001). Following regression analysis, PPROM was significantly related to a higher incidence of invasive ventilation (odds ratio: 1.48; 95% CI: 1.13-1.92, adjusted p = 0.004) after adjusting for birth weight [odds ratio = 0.34; 95% CI: 0.33-0.43, adjusted p < 0.001], Apgar score at 10 min [odds ratio =0.61; 95% CI: 0.56-0.66, adjusted p < 0.001] and antenatal corticosteroid use (adjusted p = 0.939). (4) Conclusions: PPROM was associated with a 1.48-fold higher risk of needing invasive ventilation.