The effects of sustained inflation and post-inflation PEEP in acute respiratory distress syndrome due to pneumonia and traumatic lung contusion

Objective

To investigate the response to a sustained inflation (SI) and post-inflation PEEP (PI-PEEP) in acute respiratory distress syndrome (ARDS) due to pneumonia and traumatic lung contusion.

Methods

Twenty-five patients with ARDS were enrolled (pneumonia n = 13, lung contusion n = 12). During baseline ventilation, 7 ml/kg tidal volume, 12–15 breaths/min respiratory rate and an I:E ratio of 1:2 were used. SI was performed by 45 cmH₂O continuous positive airway pressure for 30 s. PI-PEEP was titrated decrementally starting from 20 cmH₂O in order to find the best PEEP. FiO₂ was decreased under baseline ventilation. If the peak inspiratory pressure exceeded 45 cmH₂O with 20 cmH₂O PEEP, the PEEP was reduced by 1 cmH₂O decrements. Blood gas analyses were performed at baseline, 15th minute, first hour, fourth hour and sixth hour after SI.

Results

Demographic data are presented in Table 1. PI-PEEP levels were set at 16.1 ± 1.6 cmH₂O in the pneumonia group and 15.9 ± 3.1 cmH₂O in the lung contusion group (P = 0.9). Following SI, the PaO₂/FiO₂ ratio improved in all of the patients (Table 2 and Fig. 1).

Table 1 (abstract P103)

Table 2 (abstract P103)

Figure 1

(abstract P103)

Conclusions

SI followed by high levels of PI-PEEP provided an increase in arterial oxygenation in both ARDS forms. However, this strategy was found to be more effective in improving arterial oxygenation in the lung contusion group. This finding might address the idea that physiopathology of two pulmonary insults of ARDS presents in different forms.