Side effects of endotracheal suction in pressure- and volume-controlled ventilation.

STUDY OBJECTIVES

To investigate the effects of endotracheal suction in volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) with an open suction system (OSS) or a closed suction system (CSS).

DESIGN

Randomized comparison.

SETTING

Animal research laboratory.

PATIENTS

Twelve healthy anesthetized pigs.

INTERVENTIONS

The effects of endotracheal suction during VCV and PCV with tidal volume (VT) of 14 mL/kg were compared. A 60-mm inner-diameter endotracheal tube was used. Ten-second suction was performed using OSS and CSS with 12F and 14F catheters connected to - 14 kPa vacuum.

MEASUREMENTS AND RESULTS

Thirty minutes after suction in PCV, VT was still decreased by 27% (p < 0.001), compliance (Crs) by 28% (p < 0.001), and PaO(2) by 26% (p < 0.001); PaCO(2) was increased by 42% (p < 0.0001) and venous admixture by 158% (p = 0.003). Suction in VCV affected only Crs (decreased by 23%, p < 0.001) and plateau pressure (increased by 24%, p < 0.001). The initial impairment of gas exchange following suction in VCV was no longer statistically significant after 30 min.

CONCLUSIONS

In conclusion, endotracheal suction causes lung collapse leading to impaired gas exchange, an effect that is more severe and persistent in PCV than in VCV.