Pleural pressure changes in dogs measured from suprasternal fossa movements

Abstract

Movements of the suprasternal fossa during spontaneous breathing monitored with the surface inductive plethysmograph (SIP) have been shown to reflect changes of intrapleural pressure in conscious humans. Calibration of this device in anesthetized intubated dogs was accomplished by adjusting the electrical gain of its analog waveform to be equivalent to changes of airway pressure during inspiratory efforts against an occluded airway. This procedure, denoted the occlusion test, was also used to identify the site of esophageal balloon catheter placement for its recording of intrapleural pressure deflections. The validity of SIP-derived estimates of inspiratory and expiratory pulmonary resistances and lung compliance was established by finding close agreement with measurements obtained with intraesophageal pressure changes during 1) unimpeded spontaneous breathing, 2) inspiratory resistive loading, 3) bronchoprovocation with aerosolized carbachol, 4) mechanical ventilatory modalities, and 5) induced pulmonary edema. Therefore, movements of the suprasternal fossa with respiration can be reliably transformed into quantitative or semiquantitative changes of intrapleural pressure in anesthetized intubated dogs during major alterations of pulmonary mechanics.

Telemetric Recording of Intrapleural Pressure

“…8 Table 1). The measured expiratory IPP had a mean value of Ϫ11.0 Ϯ 12.9 mmHg, and a median of Ϫ6.4 (Ϫ12.9, Ϫ2.6) mmHg (Table 1).…”

Noninvasive determination of upper airway resistance and flow limitation

“…Several previous studies have attempted to ascertain upper airway mechanics noninvasively. Surface inductive plethysmography is based on the observation that there is inward movement of the suprasternal fossa during inspiration (31,36). This method has been used to measure pleural pressures and compliance in humans (36) and Rua in intubated dogs (31).…”

“…Surface inductive plethysmography is based on the observation that there is inward movement of the suprasternal fossa during inspiration (31,36). This method has been used to measure pleural pressures and compliance in humans (36) and Rua in intubated dogs (31). In dogs, there was close agreement between Rua measured by surface inductive plethysmography and esophageal pressure under a variety of conditions, including spontaneous breathing, inspiratory resistive loading, and bronchoprovocation.…”