Optimal Connection for Tiotropium SMI Delivery through Mechanical Ventilation: An In Vitro Study

We aimed to quantify Soft Mist Inhalers (SMI) delivery to spontaneous breathing model and compare with different adapters via endotracheal tube during mechanical ventilation or by manual resuscitation. A tiotropium SMI was used with a commercial in-line adapter and a T-adapter placed between the Y-adapter and the inspiratory limb of the ventilator circuit during mechanical ventilation. The SMI was actuated at the beginning of inspiration and expiration. In separate experiments, a manual resuscitator with T-adapter was attached to endotracheal tube, collecting filter, and a passive test lung. Drug was eluted from collecting filters with salt-based solvent and analyzed using high-performance liquid chromatography. Results showed the percent of SMI label dose inhaled was 3-fold higher with the commercial in-line adapter with actuation during expiration than when synchronized with inspiration. SMI with T-adapter delivery via ventilator was similar to inhalation (1.20%) or exhalation (1.02%), and both had lower delivery dose than with manual resuscitator (2.80%; p = 0.01). The inhaled dose via endotracheal tube was much lower than inhaled dose with spontaneous breathing (22.08%). In conclusion, the inhaled dose with the commercial adapter was higher with SMI actuated during expiration, but still far less than reported spontaneous inhaled dose.

Application of Non-Symmetric Bending Principles on Modelling Fatigue Crack Behaviour and Vibration of a Cracked Rotor

Many studies on cracked rotors developed crack breathing models that assume that the neutral axis of bending always remains horizontal for simplification. These models may generate significant discrepancies and thus there is a need to develop more sophisticated models to look into the shifting of the neutral axis for a cracked rotor. Herein, a case study on the shifting of the neutral axis for a cracked rotor is firstly performed by using a three-dimensional finite element model to confirm that the neutral axis becomes inclined as the cracked rotor rotates. In response to this finding, non-symmetric bending principles are used to develop a new crack breathing model which has the advantage of being able to numerically calculate the inclination angle of the neutral axis. When compared to an existing crack model in the literature that assumes that the neutral axis remains horizontal (HNA model), the proposed model is relatively less stiff in bending as a result of an overall lower area moment of inertia. Using the harmonic balance method, a two-dimensional finite element vibration model of a cracked rotor was devised by employing the proposed crack breathing model and the HNA model for validation. It can be found that the vibration amplitudes of the first three frequency components are similar between the two models for shallow cracks and significantly differed for deep cracks. This result highlights the potential of the proposed model for modelling and detecting mid-to-late-stage cracks in rotors.

Forensic Engineering Evaluation Of Co2 Re-Breathing In Infant Bedding Materials

A Four-Month-Old Infant Suffocated In His Sleep From Positional Asphyxia. The Baby Was Found Face Down On A Foam Wedge Pillow Called A Sleep Positioner. The Author Was Engaged To Evaluate The Sleep Positioner Product For Its Potential To Cause Carbon Dioxide (Co2) Re-Breathing In Infants. Prior Research On This Subject Had Already Established A Reliable Method Of Simulating Infant Breathing And Measurement Of Respiratory Gas Constituents Using A Mechanical Breathing Model. Guided By This Research, A Mechanical Breathing Model And Gas Sampling Apparatus Was Coupled To A Mannequin Representing The Child In This Matter. The Mannequin Was Placed In Face-Down And Sidefacing Positions On The Sleep Positioner Product And Twelve Other Surfaces, Including A Plain Cotton Sheet As The Baseline. The Sleep Positioner Product Produced The Highest (And Most Dangerous) Level Of Co2 Re-Breathing, More Than Three Times The Baseline Level. Factors Contributing To Co2 Re-Breathing Are Discussed.