Aim We hypothesised that short-term application of bi-level nasal continuous positive airway pressure CPAP (SiPAP) compared with conventional nasal CPAP (nCPAP) at the same mean airway pressure in infants with persistent oxygen need recovering from respiratory distress syndrome would improve CO2 removal with no change in oxygen requirement.Design Non-blinded, randomised, observational four-period crossover study.Setting/population Level III NICU; low-birthweight infants requiring CPAP and oxygen while recovering from respiratory distress syndrome.Methods Infants requiring nasal CPAP for >24h prior to study enrolment, and fraction of inspired oxygen requirement (FiO(2)) of 0.25-0.5, were randomised to either nCPAP or SiPAP. A crossover design with four 1 h treatment periods was used such that each infant received both treatments twice. Oxygen saturations (SaO(2)), transcutaneous CO2 (tcCO(2)) and vital signs were monitored continuously. Polysomnographic recordings were analysed for apnoea, bradycardia and oxygen desaturation.Results Twenty low-birthweight infants receiving 0.30.04% supplemental oxygen on CPAP of 6 cm H2O were studied at an average of 33days of age (23days, SD). There were no differences in tcCO(2) or other physiological parameters except mean blood pressure, which was lower during nCPAP (52.3 +/- 8.3 vs 54.4 +/- 9.1mmHg; +/- SD; p<0.01). No differences in short or prolonged apnoea, bradycardia or significant desaturation events were observed.Conclusions At similar mean airway pressures, SiPAP does not improve CO2 removal, oxygenation or other studied physiological parameters with the exception of mean blood pressure, which was not clinically significant.Trial registration number NCT01053455.

To determine the effectiveness of artificial surfactant therapy using KL‐4 surfactant in newborn pigs with hydrochloric acid (HCl)‐induced acute lung injury (ALI).

Premature infants are subjected to adverse effects of intubation to benefit from surfactant. We hypothesized that administration of surfactant through a laryngeal mask airway (LMA) is as effective as administration through an endotracheal tube (ETT) and that time and physiologic changes during instrumentation will be less in the LMA group. This study is a randomized, controlled trial using newborn pigs. Lung injury was induced via surfactant washout. Animals were randomized into groups: 1) LMA placed, no surfactant administered (control; n = 8); 2) surfactant via an LMA (LMA group; n = 8); and 3) surfactant via an ETT (ETT group; n = 8). We demonstrated that partial pressure of oxygen in arterial blood (Pao2) levels of the LMA and ETT groups were not statistically different. Time for successful placement of LMA was 19 ± 1 s versus ETT 123 ± 35 s (mean ± SEM); number of attempts for successful LMA placement was 1.1 (1–2) versus ETT 1.9 (1–7) [mean (range)]. Administration of surfactant via an LMA compared with an ETT resulted in similar improvements in oxygenation. Placement of the device required less time and fewer attempts. These data suggest that further study in human neonates is justified. If proven effective, some infants with respiratory distress may be able to receive surfactant while avoiding intubation.

Objectives To conduct an in Nitro evaluation of a humidified high-flow nasal cannula (HFNC) system at different flows, cannula sizes, and air leaks and also an in vivo analysis of mean end-expiratory esophageal pressure (EEEP) from nasal continuous positive airway pressure at 6 cm H2O (NCPA+6) versus HFNC.Study design In the in vitro study, we measured HFNC system pressure and flow, with varying degrees of leak and with and without the use of a pressure-limiting valve. In the in vivo study, we measured EEEP in 15 newborns on NCPAP+6 and then on HFNC at 6 L/minute, with flow decreased by 1 L/minute every 30 minutes. Heart rate, respiratory rate, fraction of inspired oxygen, arterial oxygen saturation, respiratory distress syndrome score, and EEEP were recorded for each intervention. Data analysis was done using repeated-measures analysis of variance and linear regression.Results In the in Nitro study. in the absence of leads, the pressures were limited by the pressure-limiting valve only at flows : 2 L/minute. With leaks of 30% and 50%, delivered pressures were always < 3 cm H2O. In the in vivo study, respiratory rate increased from baseline (NCPAP+6) as flow decreased (P < .02). Intrapatient and interpatient coefficients of variation were always high.Conclusions A pressure-limiting valve is necessary in a HFNC system. Although mean EEEP levels were similar in NCPAP+6 and HFNC, tachypnea developed as flow diminished. This system apparently cannot predict EEEP, because of interpatient and intrapatient variation. (J Pediatr 2009;154:177-82)

Background Humidified high flow nasal cannulae (HHNC) are used in NICUs to deliver oxygen and continuous positive airway pressure. Few data exist regarding these systems. Objective Analyze pressures delivered by the Fisher & Paykel RT329 HHNC system at varying gas flows both in vitro with varying cannula sizes and air leaks and in vivo in a neonatal piglet model. Methods In vitro: Pressure and flow derived at different points in the RT329 system were measured with a flow analyzer (Fluke Biomedical, Everett, WA) at 0%, 30%, and 50% leaks. Fixed variables included initial flow (0.5-6 lpm) and cannula size. Continuous variables included pressure and flow at various points in the system. In vivo: We measured esophageal pressures (Pes) generated at flow levels ranging from 1 to 6 lpm in seven newborn piglets. Results In vitro: Pressure delivery within the system was limited by the pop-off valve (40 cmH2O); flow delivery was preserved to the point of nasal cannula insertion. Pressure and flow delivery at the cannula end was limited at > 2 lpm. With all cannula sizes, introduction of a 30% and 50% leak resulted in > 96% and > 98% decrease in delivered pressure, respectively. With all cannulae, removal of the pop-off valve resulted in a direct increase in pressure delivery as the flow was increased: 2 lpm > 80 cmH2O, 3 lpm > 140 cmH2O, 4 lpm > 210 cmH2O, 5 lpm > 220 cmH2O, and 6 lpm > 280 cmH2O. In vivo: As HHNC flow was increased from 1 lpm to 6 lpm, mean Pes increased, but extreme variation suggests a variable leak (figure values are mean ± SD). Conclusion In vitro using the RT329 system with no leak, we saw high pressures, only limited by the pop-off valve, at flows > 2 lpm. Addition of a 30 to 50% leak at the cannula end dramatically reduced delivered pressures to