An alternative method for measuring total respiratory resistance during quiet breathing: a feasibility and validation study.

OBJECTIVE: Determining the respiratory system's mechanical properties with minimal patient effort has been an important field of investigation addressing patients unable to perform pulmonary function testing and in light of the preventive measures due to the recent pandemic. The current study aimed to present an alternative method for total respiratory resistance measurement during tidal breathing, compare it with airway resistance (Raw), measured by body plethysmography, and validate the procedure in three groups of subjects with normal, constrictive and obstructive respiratory patterns in spirometry. PATIENTS AND METHODS: We developed an alternative method of assessing total respiratory resistance during quiet breathing. After manufacturing the appropriate hardware apparatus, we applied a steady extrinsic resistance (ΔR) for 100-200 m/s during tidal breathing. Α theoretical mathematical model allowed measurement of total respiratory resistance (Rtot) during inspiration (Rin) and expiration (Rex). To validate the method, 15 individuals were enrolled and assigned to the normal, obstructive and restrictive groups based on their spirometry patterns. All groups participated in two sets of measurements, the plethysmographic and novel method. Finally, respiratory resistance measurements were compared between groups and methods. RESULTS: The method was successfully developed, and Rtot measurements were recorded in five normal subjects and in five obstructive and restrictive subjects. Mean Rin and mean Rex were 4.99 cm H2O/L/sec and 4.42 cm H2O/L/sec in the healthy, 4.87 cm H2O/L/sec, and 6.63 cm H2O/L/sec in the obstructive and 5.97 cm H2O/L/sec and 4.12 cm H2O/L/sec in the restrictive group, respectively. Rex was notably higher than Rin in the obstructive group and was positively correlated with Raw (p<0.005, r=0.47). CONCLUSIONS: This method provides the theoretical background for a plausible alternative tool for accessing a mechanical parameter of the respiratory system, which is easy to perform and requires only passive patient cooperation while enabling rough differentiation between obstructive and restrictive disorders. The model's feasibility potential in a real-life setting was studied in a small sample, and additional implementation and validation of the method in a larger population are guaranteed.

Particulate matter in aerosols produced by two last generation electronic cigarettes: a comparison in a real-world environment.

The design of e-cigarettes (e-cigs) is constantly evolving and the latest models can aerosolize using high-power sub-ohm resistance and hence may produce specific particle concentrations. The aim of this study was to evaluate the aerosol characteristics generated by two different types of electronic cigarette in real-world conditions, such as a sitting room or a small office, in number of particles (particles/cm3). We compared the real time and time-integrated measurements of the aerosol generated by the e-cigarette types Just Fog and JUUL. Real time (10s average) number of particles (particles/cm3) in 8 different aerodynamic sizes was measured using an optical particle counter (OPC) model Profiler 212-2. Tests were conducted with and without a Heating, Ventilating Air Conditioning System (HVACS) in operation, in order to evaluate the efficiency of air filtration. During the vaping sessions the OPC recorded quite significant increases in number of particles/cm3. The JUUL e-cig produced significantly lower emissions than Just Fog with and without the HVACS in operation. The study demonstrates the rapid volatility or change from liquid or semi-liquid to gaseous status of the e-cig aerosols, with half-life in the order of a few seconds (min. 4.6, max 23.9), even without the HVACS in operation. The e-cig aerosol generated by the JUUL proved significantly lower than that generated by the Just Fog, but this reduction may not be sufficient to eliminate or consistently reduce the health risk for vulnerable non e-cig users exposed to it.

Documentation of Legionella pneumophila and Mycobacterium tuberculosis co-existence in a patient with acute respiratory distress syndrome.

BACKGROUND: Bacterial lung infections are common causes of ARDS and, despite intensive research for decades, the mortality rate remains very high. Only two reports suggest the co-existence of Legionnaires' disease and pulmonary tuberculosis based mainly on clinical presentation and serologic results for Legionella and positive cultures for Mycobacterium tuberculosis (M. tuberculosis). MATERIALS AND METHODS: A variety of specimens from a 61-year-old man was used for detection of Legionella pneumophila (L. pneumophila) and M. tuberculosis by PCR. Further identification of the pathogens was carried out by sequence analysis. RESULTS: L. pneumophila region mip was detected in bronchial washings, bronchoalveolar lavage and urine specimens of the patient. M. tuberculosis regions IS6110 and mtp40 were detected in endo-bronchial secretions and bronchoalveolar lavage. CONCLUSION: By using polymerase chain reaction (PCR) and DNA sequencing we documented L. pneumophila and M. tuberculosis co-existence, in multiple specimens of a patient presenting with acute respiratory distress syndrome (ARDS). Furthermore, the efficacy of the specific antibiotic treatment, based on the PCR results, suggest the co-existence of these two pathogens.