Elastic characteristics of the airway wall

Abstract

To examine the elastic behavior of the upper airway, we obtained pressure-area plots from data gathered from acoustic images of the airway and measurements of mouth pressure during tidal breathing in 10 adult human volunteers (dA/dP). These plots revealed both tidal hysteresis and a change in slope as a function of distance along the airway. The slope of the regression line of the dA/dP plots decreased from the pharyngeal region to the trachea and became 0 at the thoracic inlet, the location of which was independently assessed. In most subjects the slope became negative distal to the thoracic inlet. Correlation coefficients between pressure and area approached 1 in the pharyngeal region and 0 at the thoracic inlet. When subjects breathed against a small resistive load (10 cmH2O.1(-1).s) pharyngeal, extrathoracic, and intrathoracic pressure-area plots were exaggerated but the slope at the thoracic inlet was unchanged. We conclude that this pressure-area characteristic defines regional differences in upper airway elasticity and delineates the transition point between the intra- and extrathoracic airways.

Pharyngeal Cross-Sectional Area and Pharyngeal Compliance in Normal Males and Females

“…Although Fouke et al [25] used the same resistance method as ours, several different methods were also employed [1,19,24]. In contrast to the fact that the standard method (occlusion method) measures the compliance at a constant lung volume, e.g.…”

Scientific Rationale for the Use of Alpha-Adrenergic Agonists and Glucocorticoids in the Therapy of Pediatric Stridor

“…This concept is important because the majority of pediatric conditions associated with stridor and upper airway obstruction are characterized by dynamic inspiratory collapse of the upper airway [1–3]. Indeed, there is compelling evidence demonstrating that α AR-agonists enhance both nasal cavity cross-sectional area and nasal airflow, assessed by acoustic rhinometry (AR) [19, 20] and peak nasal inspiratory flow (PNIF), respectively [21].…”

“…Even though there are many disorders that can induce stridor, they often share a common pathophysiology producing dynamic collapse of the extrathoracic airway during inspiration [1, 2]. This resultant inspiratory flow limitation may be associated with a range of impairment, producing increasing breathing efforts and distress.…”

Acoustic method to quantitatively assess the position and patency of infant endotracheal tubes: preliminary results in rabbits

“…Later, the acoustic airway reflection response was processed with a recursive method developed by Ware and Aki 12 to estimate the impedance and cross-sectional area profiles of canine airways, 13,14 human airways, [15][16][17][18] and physical models. 19 Subsequent clinical and physiological investigations used this method to examine morphological 20,21 and mechanical 22 characteristics of the upper airway and trachea. One particular study used acoustic reflectometry and the Ware-Aki recursion algorithm to infer the longitudinal area profile of an ETT to detect mucus secretions.…”