Validation of the disposable T-piece resuscitator (Neo-Tee): a bench study.

OBJECTIVE: The Neo-Tee Infant T-piece resuscitator is a disposable T-piece resuscitator. The aim of this bench study was to assess the accuracy of the Neo-Tee using a measurement set-up and settings mimicking clinical practice. STUDY DESIGN: Nine Neo-Tee devices were tested using a face mask interface and a manikin. Pressures were set using the built-in manometer and simultaneously measured at the interface. Peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP) were studied under static conditions and positive pressure ventilation (PPV), using a wide range of clinically relevant flows and pressures. Pressures were measured without adjusting for a possible offset of PIP and PEEP after switching from static pressures to PPV. In an additional subset of measurements, PIP/PEEP offsets on the Neo-Tee manometer after starting PPV were adjusted. RESULTS: Under static conditions, setting the PEEP level with the Neo-Tee manometer results in overestimation of the true PEEP applied at the airway opening, with a difference of approximately 1.5 cmH2O. When switching to PPV, this difference almost disappears. In contrast to PEEP, PIP levels measured at the airway opening were accurate.Adjusting PIP and PEEP on the built-in manometer after starting PPV was necessary in all measurements, but this did not improve the accuracy of the targeted pressure delivery, especially for PEEP. A gas flow rate of 5 L/min was insufficient to reach commonly used PEEP levels of 5 cmH2O. CONCLUSION: The Neo-Tee T-piece resuscitator is accurate for delivering a static inflation and PPV, but not for delivering continuous positive airway pressure.

D-amino acid aberrations in cerebrospinal fluid and plasma of smokers.

The glutamatergic neurotransmission system and the N-methyl-D-aspartate receptor (NMDAR) have been implicated in smoking and alcohol consumption behavior. Preclinical studies have demonstrated that nicotine and ethanol influence NMDAR functionality, which may have a role in tendencies to consume these substances. Nonetheless, little is known about concentrations of NMDAR coagonists in the cerebrospinal fluid (CSF) and plasma of individuals who smoke or consume alcohol. Glycine and L- and D-stereoisomers of alanine, serine, and proline were therefore measured using ultra-high-performance liquid chromatography-tandem mass spectrometry in 403 healthy subjects. Nicotine and alcohol consumption were quantified using questionnaires. Possible differences in NMDAR coagonist concentrations in plasma and CSF were investigated using ANCOVA with age, body mass index, and storage duration as covariates. The significance threshold was Bonferroni corrected (α=0.00625). Compared with non-smokers, smokers displayed lower levels of D-proline in plasma (p=0.0027, Cohen's d=-0.41) and D-proline in CSF (p=0.0026, Cohen's d=-0.43). D-Serine in CSF was higher in smokers than in non-smokers (p=0.0052, Cohen's d=0.41). After subdividing participants based on smoking quantity, dose-dependent decreases were demonstrated in smokers for D-proline in plasma (F=5.65, p=0.0039) and D-proline in CSF (F=5.20, p=0.0060). No differences in NMDAR coagonist levels between alcohol consumption groups were detected. To our knowledge, this is the first report to implicate D-amino acids in smoking behavior of humans. Whether such concentration differences lie at the root of or result from smoking habits may be addressed in prospective studies.