Pharyngeal pressure due to high-flow nasal cannula devices in preterm infants.

BACKGROUND: In infants, a high-flow nasal cannula (HFNC) generates continuous positive pressure on the upper airway. This study aimed to evaluate the association between pharyngeal pressure and flow rate, and the association between pharyngeal pressure and bodyweight for two types of HFNC devices commonly used in preterm infants: the Optiflow Junior, hereafter "FP" (Fisher & Paykel, Auckland, New Zealand), and the Precision Flow, hereafter "VT" (Vapotherm, Exeter, NH, USA). METHODS: Pharyngeal pressure measurements were performed in 12 preterm infants who received HFNC support. Flow rates of 1 to 4 L/kg/min were studied. RESULTS: The median weight at the time of measurement was 1,290 g (range, 953-1,932 g). The FP was used in eight infants and the VT in four. In both of the groups, the flow rate and pharyngeal pressure appeared to be positively correlated except for the premature cannula in the FP group. At a flow rate of ≥2 L/kg/min, there was a positive correlation between the bodyweight and pharyngeal pressure in infants with premature and neonatal cannulas in the FP group. Conversely, at the same flow rate, there was a negative correlation between the bodyweight and pharyngeal pressure in infants with a SOLO cannula in the VT group. CONCLUSIONS: In preterm infants, the flow rate and pharyngeal pressure were positively correlated in many HFNC cannulas. However, the pharyngeal pressure and bodyweight appeared to be positively and negatively correlated in the FP and VT groups, respectively. Future studies with larger sample sizes should further investigate this issue.

Evaluation of respiratory center function in congenital central hypoventilation syndrome by monitoring electrical activity of the diaphragm.

BACKGROUND: A definitive diagnosis of congenital central hypoventilation syndrome (CCHS) is made by genetic testing. However, there are only a few examinations that warrant genetic testing. Electrical activity of the diaphragm (Edi) reflects neural respiratory drive from respiratory center to diaphragm. We evaluated the function of the respiratory center in CCHS by Edi monitoring. METHODS: Monitoring of Edi was performed in six CCHS cases without mechanical ventilation. The monitoring time was 30 consecutive minutes from wakefulness to sleep. The TcPCO2 or EtCO2 and SpO2 were recorded simultaneously. RESULTS: The Edi peak during wakefulness was 14.0 (10.3-21.0) µV and the Edi peak during sleep was 6.7 (3.8-8.0) µV. The Edi peak during sleep was significantly lower than the Edi peak during wakefulness, and patients were in a state of hypoventilation. Although TcPCO2 or EtCO2 increased due to hypoventilation, an increase in the Edi peak that reflects central respiratory drive was not observed. ΔEdi/ΔCO2 was -0.06µV/mmHg. Maximum EtCO2 or TcPco2 was 51 mmHg, and the average SpO2 was 91.5% during monitoring. CONCLUSIONS: We confirmed that Edi monitoring could evaluate the function of the respiratory center and reproduce the hypoventilation of CCHS. The present study suggested that Edi monitoring is a useful examination in deciding whether to perform genetic testing or not and it may lead to an early diagnosis of CCHS.

Novel treatment strategy for Japanese newborns with high serum unbound bilirubin.

BACKGROUND: Serum unbound bilirubin (UB) is a measure of bilirubin not bound to albumin, and has been reported to be better than total bilirubin level at identifying infants at risk of developing bilirubin-induced neurotoxicity, including auditory abnormalities. A detailed treatment strategy for newborns with high serum UB has not been established. The aim of this study was to assess auditory outcomes in newborns with serum UB ≥1.00 µg/dL who were treated according to a novel treatment protocol. METHODS: A prospective clinical study was conducted in newborns weighing >1500 g with serum UB ≥1.00 µg/dL who were admitted to Kobe University Hospital and Kakogawa Municipal Hospital, Japan from 2006 to 2011. Enrolled newborns were treated as follows: (i) if serum UB was 1.00-1.50 µg/dL, phototherapy and infusion were given with or without albumin or immunoglobulin therapy; and (ii) if serum UB was >1.50 µg/dL, exchange transfusion was performed immediately. Auditory brainstem responses were evaluated at the time of discharge. RESULTS: A total of 89 Japanese newborns with UB ≥1.00 µg/dL were enrolled at a median age of 4 days. Of these, 85 had UB 1.00-1.50 µg/dL and four had UB >1.50 µg/dL. After being treated according to the protocol, no newborns were diagnosed with auditory brainstem response abnormalities. CONCLUSIONS: The present treatment protocol for Japanese newborns with serum UB ≥1.00 µg/dL may be useful for the prevention of bilirubin-induced auditory abnormalities.

Synthesis of Li2Ti3O7 Anode Materials by Ultrasonic Spray Pyrolysis and Their Electrochemical Properties.

Ramsdellite-type lithium titanate (Li2Ti3O7) powders were synthesized by performing ultrasonic spray pyrolysis, and their chemical and physical properties were characterized by performing Scanning Electron Microscope (SEM), powder X-ray Diffraction (XRD), and Inductively Coupled Plasma (ICP) analyses. The as-prepared Li2Ti3O7 precursor powders had spherical morphologies with hollow microstructures, but an irregularly shaped morphology was obtained after calcination above 900 °C. The ramsdellite Li2Ti3O7 crystal phase was obtained after the calcination at 1100 °C under an argon/hydrogen atmosphere. The first rechargeable capacity of the Li2Ti3O7 anode material was 168 mAh/g at 0.1 C and 82 mAh/g at 20 C, and the discharge capacity retention ratio was 99% at 1 C after the 500th cycle. The cycle performance of the Li2Ti3O7 anode was also highly stable at 50 °C, demonstrating the superiority of Li2Ti3O7 anode materials reported previously.

Kinetics of iterative carbohydrate transfer to polysaccharide catalyzed by chondroitin polymerase on a highly sensitive flow-type 27†MHz quartz-crystal microbalance.

Using a highly sensitive flow-type 27 MHz quartz crystal microbalance, we could detect a small mass change during stepwise and alternating one-sugar transfer of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) to an acceptor, catalyzed by chondroitin polymerase from Escherichia coli strain K4 (K4CP), and analyze the elongation mechanism of K4CP. K4CP was found to bind strongly to a chondroitin acceptor (K(d)=0.97 µM). Although the binding affinity and the catalytic rate constant for each monomer were considerably different, the apparent catalytic efficiency (k(cat)/K(m)) was similar (6.3×10(4) M(-1) s(-1) for GlcA transfer and 3.4×10(4) M(-1) s(-1) for the GalNAc transfer). This is reasonable for the smooth alternating elongation of GlcA and GalNAc on the acceptor. This is the first study to report the determination of kinetic parameters for enzymatic, alternated, sugar elongation.