Airway Resistance

BackgroundPulmonary function measurements are important when studying respiratory disease models. Both resistance and compliance have been used to assess lung function in mice. Yet, it is not always clear how these parameters relate to forced expiration (FE)-related parameters, most commonly used in humans. We aimed to characterize FE measurements in four well-established mouse models of lung diseases.MethodDetailed respiratory mechanics and FE measurements were assessed concurrently in Balb/c mice, using the forced oscillation and negative pressure-driven forced expiration techniques, respectively. Measurements were performed at baseline and following increasing methacholine challenges in control Balb/c mice as well as in four disease models: bleomycin-induced fibrosis, elastase-induced emphysema, LPS-induced acute lung injury and house dust mite-induced asthma.ResultsRespiratory mechanics parameters (airway resistance, tissue damping and tissue elastance) confirmed disease-specific phenotypes either at baseline or following methacholine challenge. Similarly, lung function defects could be detected in each disease model by at least one FE-related parameter (FEV0.1, FEF0.1, FVC, FEV0.1/FVC ratio and PEF) at baseline or during the methacholine provocation assay.ConclusionsFE-derived outcomes in four mouse disease models behaved similarly to changes found in human spirometry. Routine combined lung function assessments could increase the translational utility of mouse models.

UnlabelledMandibular cross-sectional deficiency is a dentofacial defect in connection with the narrowing of the mandibular arch width. This abnormality is a significant etiopathogenic factor and it is often associated with nasal breathing difficulties. This atresia may be treated through Rapid Maxillary Expansion or Surgically Assisted Rapid Maxillary Expansion, depending on the patient's age. Both procedures will change the craniofacial structure, especially the nasal cavity.AimBased on literature review, the purpose of this paper was to report the relationship among maxillary expansion, nasal cavity and Nasal Airflow Resistance.MethodA non-systematic literary review was conducted in search of experimental studies to treat maxillary atresia. Papers considering Rapid Maxillary Expansion and Surgically Assisted Rapid Maxillary Expansion were included, whereas those using Maxillary Expansion through Segmented Osteotomy were excluded.ResultRapid Maxillary Expansion and Surgically Assisted Rapid Maxillary Expansion cause dentofacial changes, especially in the nasal cavity. Consequently, the nose width enlarges, reducing Nasal Airflow Resistance.ConclusionAnteroposterior cephalometric studies show evidence of an enlarged nasal cavity following maxillary expansion.

Rhinomanometry can still be considered as the standard technique for the objective assessment of the ventilatory function of the nose. Reliable technical requirements are given by fast digital sensors and modern information technology. However, the xyimaging of the pressure-flow relation typically shows loops as a sign of hysteresis, with the need for resolution of the breath in four phases. The three pillars of 4-phase rhinomanometry (4PR) are the replacement of estimations by measurements, the introduction of parameters related to the subjective sensing of obstruction, and the graphical information regarding the disturbed function of the nasal valve. In a meta-analysis of 36,563 clinical measurements, we analyze the errors of the "classic" parameters (flow in 150 Pa) and reject the further use of these parameters as obsolete, because they correspond to an inaccurate estimation rather than proper measurement. In a pre-study of 1580 measurements, the logarithmic effective resistance (Reff) was found to have the highest correlation with values obtained from a visual analog scale. Next, we classify the inspiratory effective resistance in 20,069 measurements without treatment and 16,494 measurements after decongestion with xylometazoline 0.1 % spray in 20 % percentiles. The gradation of obstruction delivers not only "normal" values but also indications for the severity of the obstruction in adult Caucasian noses. Adoption of the distribution for the growing nose and analysis of the total nasal resistance is addressed, and typical findings of nasal valve phenomena are outlined.

The interaction between anatomical structures, pressure, and airflow impacts the airway resistance. The airflow during noninvasive ventilation (NIV) relies on the upper airway and laryngeal patency. This study aimed to quantify the airflow resistance at these levels during NIV. In this cross-sectional study examining 10 healthy, awake adults, we established a NIV setup incorporating a continuous video-recorded transnasal laryngoscopy and simultaneous airway pressure measurement using a transducer positioned above and below the vocal folds. Airflow and mask pressure were recorded by a pneumotachograph at the mask. NIV was delivered with inspiratory positive pressure (IPAP)/expiratory positive pressure (EPAP) set to 10/4 and 15/4 cmH2O. Upper airway (Ruaw) and translaryngeal (Rtl) resistance were calculated and compared with laryngoscopic findings. During IPAP10/EPAP4, the Ruaw was 4.25/4.21 and Rtl 2.20/3.45. During IPAP15/EPAP4, the Ruaw was 5.18/5.73, and the Rtl was 2.31/3.83. Ruaw was significantly higher than Rtl for inspiration at both IPAP levels (p = 0.001 and p = 0.012), and for expiration with IPAP15/EPAP4 (p = 0.048). The resistance appeared dynamic during the NIV cycle, and the findings aligned with the laryngoscopic observations. NIV modulates upper airway and translaryngeal resistance. Resistance increases with elevated IPAP levels, particularly within the upper airway.