An Innovative Air-Oxygen Blender for Continuous Positive Airway Pressure Support in Resource-Poor Locations: A Feasibility Study.

Objectives: The objectives of this study are (i) to evaluate the feasibility of using an inexpensive air pump to maintain reliable oxygen concentration in a continuous positive airway pressure (CPAP) system and (ii) to evaluate whether an inexpensive air pump can maintain infant 02 sats >90%. Methods: This prospective study, which included 19 babies in pilot phase and 90 during extension phase, was conducted at a neonatal intensive care unit in a resource-poor academic medical center in India. The intervention involved introduction of an air pump in the CPAP delivery system. Outcome measures were oxygen concentration in the air-oxygen blend and oxygen saturation of the study babies. Results: Oxygen concentration at the outlets ranged between 56 and 70% and in the blend between 42 and 51%. Oxygen saturation ranged between 90 and 97%. Conclusion: A simple and inexpensive air pump can work as a safe and effective oxygen blender.

Effect of repeated freezing and thawing on 18 clinical chemistry analytes in rat serum.

In a preclinical research laboratory, using serum samples that have been frozen and thawed repeatedly is sometimes unavoidable when needing to confirm previous results or perform additional analysis. Here we determined the effects of multiple cycles of refrigeration or freezing and thawing of rat serum at 3 temperature conditions for different storage times on clinical chemistry analytes. Serum samples obtained from adult Wistar rats were stored at 2 to 8 °C and -10 to -20 °C for as long as 72 h and at -70 °C for as long as 30 d. At different time points (24, 48, and 72 h for samples stored at 2 to 8 °C or -10 to -20 °C and 1, 7, and 30 d for samples stored at -70 °C), the samples were brought to room temperature, analyzed, and then stored again at the designated temperature. The results obtained after each storage cycle were compared with those obtained from the initial analysis of fresh samples. Of the 18 serum analytes evaluated, 14 were stable without significant changes, even after 3 freeze-thaw cycles at the tested temperature ranges. Results from this study will help researchers working with rat serum to interpret the biochemical data obtained from serum samples that have been frozen and thawed repeatedly.