Abstract
IntroductionVentilator-induced lung injury (VILI), one of the most serious complications of mechanical ventilation (MV), can impact patients' clinical prognoses. Compared to control ventilation, preserving spontaneous breathing can improve many physiological features in ventilated patients, such as gas distribution, cardiac performance, and ventilation-perfusion matching. However, the effect of spontaneous breathing on VILI is unknown. The goal of this study was to compare the effects of spontaneous breathing and control ventilation on lung injury in mechanically-ventilated healthy rabbits.MethodsSixteen healthy New Zealand white rabbits were randomly placed into a spontaneous breathing group (SB Group) and a control ventilation group (CV Group). Both groups were ventilated for eight hours using biphasic positive airway pressure (BIPAP) with similar ventilator parameters: inspiration pressure (PI) resulting in a tidal volume (VT) of 10 to 15 ml/kg, inspiratory-to-expiratory ratio of 1:1, positive end-expiration pressure (PEEP) of 2 cmH2O, and FiO2 of 0.5. Inflammatory markers in blood serum, lung homogenates and bronchoalveolar lavage fluid (BALF), total protein levels in BALF, mRNA expressions of selected cytokines in lung tissue, and lung injury histopathology scores were determined.ResultsAnimals remained hemodynamically stable throughout the entire experiment. After eight hours of MV, compared to the CV Group, the SB Group had lower PaCO2 values and ratios of dead space to tidal volume, and higher lung compliance. The levels of cytokines in blood serum and BALF in both groups were similar, but spontaneous breathing led to significantly lower cytokine mRNA expressions in lung tissues and lower lung injury histological scores.ConclusionsPreserving spontaneous breathing can not only improve ventilatory function, but can also attenuate selected markers of VILI in the mechanically-ventilated healthy lung.
Highlights
Ventilator-induced lung injury (VILI), one of the most serious complications of mechanical ventilation (MV), can impact patients’ clinical prognoses
The levels of cytokines in blood serum and bronchoalveolar lavage fluid (BALF) in both groups were similar, but spontaneous breathing led to significantly lower cytokine messenger ribonucleic acid (mRNA) expressions in lung tissues and lower lung injury histological scores
Heart rate and central venous pressure remained stable during the experiment, and there were no differences for these two variables between spontaneous breathing (SB) group and control ventilation (CV) group (Table 1)
Summary
Ventilator-induced lung injury (VILI), one of the most serious complications of mechanical ventilation (MV), can impact patients’ clinical prognoses. Compared to control ventilation, preserving spontaneous breathing can improve many physiological features in ventilated patients, such as gas distribution, cardiac performance, and ventilation-perfusion matching. Preserving spontaneous breathing is associated with fewer complications than control ventilation during positive pressure respiratory support, such as by increasing the gas distribution of dependent lung regions [11,12,13,14], improving cardiac performance [14,15,16], promoting ventilation-perfusion matching [14,15,17], preventing diaphragm disuse atrophy [18,19], and decreasing the use of sedative and analgesic drugs [16]. Several experimental studies showed that preserving spontaneous breathing during mechanical ventilation can attenuate VILI in lung with acute lung injury (ALI) [25,26,27]
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