Effect of spontaneous breathing on ventilator-induced lung injury in mechanically ventilated healthy rabbits: a randomized, controlled, experimental study

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.

Reaction products of hexamethylene diisocyanate vapors with “self” molecules in the airways of rabbits exposed via tracheostomy

“…We adapted previously published methods for maintaining spontaneous breathing via endotracheostomy in anesthetized rabbits (Xia et al, 2011) to study lower airway exposure to the occupational allergen HDI. As depicted in Figure 1, rabbits were allowed to free-breathe from a chamber filled with O 2 , or O 2 containing HDI vapor for 60 minutes.…”

“…To accomplish this goal, we adapted previously described methodology in which rabbits were anesthetized, tracheostomized and allowed to spontaneously free breathe (Xia et al, 2011) through an endotracheal tube. The use of an endotracheal tube for delivering chemical vapors bypassed the scrubbing effect of the animals’ upper airways and provided a ready port for the collection of airway fluid (via lavage) immediately following exposure.…”

“…The methodology was adapted from a previously published approach for maintaining spontaneous breathing in tracheotomized rabbits (Xia et al, 2011), and an older study (Marek et al, 1995) demonstrating the utility of oral intubation for delivering toluene diisocyanate (TDI) vapor to rabbit lower airways. In the present study, an endotracheal tube was inserted surgically, which provided a ready port for obtaining lower airway fluid (via lavage) immediately after exposure and obviated the notorious challenges of oral intubation in rabbits (Gografe et al, 2003).…”

Experiences Using Airway Pressure Release Ventilation for Pneumonia with Severe Hypercapnia or Postoperative Pulmonary Edema

“…In the randomized prospective animal studies, F-APRV was shown to be beneficial. It was shown that APRV reduced lung water and HMGB1 in rabbits [18], improved systemic and cerebrospinal blood flow in swine [16], improved oxygenation and attenuated ventilator-induced lung injury (VILI) in rabbits [26], and improved oxygenation and reduced lung injury in swine [7]. In humans, Putsenen et al showed that APRV with spontaneous breathing increased oxygenation, cardiac index, and pulmonary compliance, with reduced sedative requirements compared with CPPV in humans [39].…”

“…As described above, the APRV methodologies were subdivided into two categories: F-APRV; (Tables 1 and 3) and P-APRV (Tables 2 and 4). The majority of the animal studies (69 % of total) [2,4,[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] and human studies (82 % of total) [3, were in the F-APRV category.…”