Lung inflation/deflation

Normally, the space between the visceral and parietal pleura is only a potential space. More accurately, it is a surface covered with a thin film of fluid, to lubricate movement of the lung. Both pleura are relatively flexible and passive, and do not limit the inflation or deflation of the lungs during the breathing cycle. 

It is unlikely that a bronchodilator will be useful to Bob as his problem involves a change in the substance of the lung tissue, which restricts inflation and deflation, but there is usually little bronchoconstriction. 

The open end of the plastic cannula should be in the trachea and must not enter the bronchi. The inflation and deflation of the lungs during lavage helps the clearance of the vascular system. 

Adaptation index Response to lung deflation Pressure/volume threshold Tracheal/bronchial inflation Tracheal/bronchial deflation Termination sites <70 Not activated Low Not activated Not activated Peripheral airways/lung >70 Activated Moderate Activated Activated Trachea/carina/ mainstem bronchi ... 

An artificial lung has been developed based upon principles of gas exchange with the blood exhibited in a natural lung (Thieme, 2001b). A balloon wrapped with hollow fibers is implanted in the vena cava by means of a catheter inserted in the leg (Figure 8.2.7). The balloon inflates and deflates as many as 300 times a minute. This causes blood to pump back and forth over the fibers, allowing oxygen to enter the blood and carbon dioxide to be removed. 

The respiratory system is responsible for generating and regulating the transpulmonary pressures needed to inflate and deflate the lung. Normal gas exchange between the lung and blood requires breathing patterns that ensure appropriate alveolar ventilation. Ventilatory disorders that alter alveolar ventilation are defined as hypoventilation or hyperventilation syndromes. Hyperventilation results in an increase in the partial pressure of arterial CO2 above normal limits and can lead to acidosis, pulmonary hypertension, congestive heart failure, headache, and disturbed sleep. Hypoventilation results in a decrease in the partial pressure of arterial CO2 below normal limits and can lead to alkalosis, syncope, epileptic attacks, reduced cardiac output, and muscle weakness. 

Methodologies are currently available for measuring airway resistance and compliance in rodents and non-rodents either during spontaneous breathing (dynamic) or using a forced maneuver procedure (flow-volume or pressure-volume curves) that involves a controlled inflation and rapid deflation of the lung to evaluate forced expiratory flows and static or quasi-static compliance. The direct measurement of resistance and compliance t5q)ically requires an anesthetized model so that the airflows, pressures, and volumes can be monitored and controlled (Diamond and O DoimeU 1977 Costa et al. 1992 Mauderly 1989). 

ABSTRACT In this study, bioimpedance spectroscopy measurements ranging from 1 kHz to 1 MHz were made on post mortem lung segments of mini pigs. Healthy and partly atelectatic lungs injured by mechanical ventilation were used, both deflated and under air inflation. The results, presented on a Cole-diagram of the complex impedance, conductance by frequency and conductance differences at different frequency plots, are discussed. These data confirm that detection of certain lung diseases may be possible based on differences in impedance measured at different frequencies. 

A segment from each pig was used (S1-S5, Fig. 3). Healthy lungs (or with almost no atelectasis), as well as lungs partly collapsed and with hemorrhagic regions (atelectatic), were measured both deflated and under air inflation for this, a manual syringe (20 mL) was used (Fig. 2). Air volume was adapted to the segment size in order to achieve adequate volume extension. 

Figure 4. Estimated conductances (see section 3.2) of lung segments depending on the frequency used (1 kHz-1 MHz). (H, healthy or almost no atelectasis At, Atelectasis inf, inflated def, deflated).

Figure 5. Conductivity data from an inflated and deflated lung, and from blood and air reproduced from [7].

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