ALI, ARDS & Ventilator Research
Acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS), typically develop following an acute systemic (e.g. sepsis) or lung (e.g. pneumonia, aspiration, trauma) injury. These serious and life threatening conditions are characterized by a wide-spread lung inflammation, alveolar and capillary damage and dysfunction, as well as a long term build-up of scar tissue. From a lung function perspective, these lead to pulmonary edema formation, collapse of lung areas, poor blood oxygenation, and enhanced breathing efforts.
INTERVENTION AND MEASUREMENT DEVICE
The treatment of ARDS patients invariably involves mechanical ventilation as the level of blood oxygenation drops below critical values. While on one hand this can be beneficial for the patient, it also represents an aggravating risk factor as mechanical ventilation can also induce lung injury. Therefore in addition to studying the disease pathology associated with ARDS, researchers must also consider the impact mechanical ventilation can have on the respiratory system and how to best minimize it.
Being a highly programmable computer-controlled piston ventilator as well as a lung function measurement device, the flexiVent system has been selected by many research groups as a tool of choice in this research area. Several examples of this combination of functionalities as well as of the study design advantage that it provides can be found in the literature.
- Linking the development of ventilator-induced injury to mechanical function in the lung. – Smith et al. Ann Biomed Eng., 41: 527, 2013.
- Combined effects of ventilation mode and positive end-expiratory pressure on mechanics, gas exchange and the epithelium in mice with acute lung injury. – Thammanomai et al. PLoS One, 8: E53934, 2013.
- High tidal volume ventilation does not exacerbate acid-induced lung injury in infant rats. – Sly et al. Respir Physiol Neurobiol., 189: 129, 2013.
- TRPV4 inhibition counteracts edema and inflammation and improves pulmonary function and oxygen saturation in chemically induced acute lung injury. – Balakrishna et al. Am J Physiol Lung Cell Mol Physiol., 307(2): L158-72, 2014.
- Variable tidal volume ventilation improves lung mechanics and gas exchange in a rodent model of acute lung injury. – Arold et al. Am J Respir Crit Care Med., 165: 366, 2002.
CONTINUOUS VENTILATORY PATTERNS
Impaired pulmonary function develops as a result of ALI or ARDS. In preclinical disease models, the analysis of ventilatory patterns in conscious subjects could prove to be useful for the continuous tracking of disease progression over a given time period. Conscious monitoring with one of the various plethysmography techniques (unrestrained whole body plethysmography, double chamber plethysmography, or head-out plethysmography) is capable of tracking changes in a number of conventional parameters (i.e. tidal volume, respiratory rate, minute ventilation, peak inspiratory and expiratory flow, etc.) which could be used to follow the functional consequences of the lung injury. There are many examples in literature of the use of ventilatory parameters to track changes and monitor the effects of induced lung insults.