Effects of Expiratory Rib Cage Compression Combined With Endotracheal Suctioning on Gas Exchange in Mechanically Ventilated Rabbits With Induced Atelectasis

INTRODUCTION: In Japan, expiratory rib cage compression (a chest physiotherapy technique) is frequently used with mechanically ventilated patients. It has not been determined whether rib cage compression combined with endotracheal suctioning improves oxygenation, ventilation, and mucus clearance. We evaluated the effects of rib cage compression with and without endotracheal suctioning on P_aO2, P_aCO2, dynamic compliance of the respiratory system (C_RS), and mucus clearance in rabbits with induced atelectasis.

METHODS: Anesthetized adult rabbits had an 18-gauge catheter placed into the airway, together with a tracheal tube via tracheostoma, and were mechanically ventilated. To create atelectasis, artificial mucus was infused into the airway via the catheter. Each rabbit was randomly assigned to one of 4 groups (n = 7 in each): (1) control, (2) received endotracheal suctioning alone, (3) received rib cage compression alone, and (4) received both rib cage compression and endotracheal suctioning. After these interventions, for 30 min, each animal was placed supine without intervention for 120 min.

RESULTS: In the groups that received rib cage compression, oxygenation, ventilation, and C_RS were significantly worse than the groups that did not receive rib cage compression (p < 0.05). Endotracheal suctioning with and without rib cage compression did not improve oxygenation, C_RS, or mucus clearance. There were no significant differences in the weight of aspirated artificial mucus between the groups, with or without rib cage compression.

CONCLUSIONS: In mechanically ventilated rabbits that had induced atelectasis, neither rib cage compression alone nor rib cage compression combined with endotracheal suctioning improved oxygenation, ventilation, C_RS, or mucus clearance. Alveolar and airway collapse was probably exacerbated by rib cage compression.