Impact of catheter size and endotracheal tube diameter on PEEP stability during closed suctioning in a simulated ARDS patient: a bench top study

Objectives: Endotracheal suctioning is performed in mechanically ventilated patients to remove airway secretions. The American Association for Respiratory Care (AARC) has provided recommendations on endotracheal suctioning techniques and catheter size selection over the years (1993, 2010, 2022). This bench-top study aimed to compare the effects of closed-suction system manoeuvres performed with different catheter diameters on PEEP and Tidal Volume in an experimental setup of mechanical ventilation in a simulated ARDS scenario. Methods: A lung simulator was used to simulate severe ARDS in adult patients. Endotracheal suctioning was performed using a closed suction system with two catheter sizes (12 and 14 Fr). and two endotracheal tube diameters (7 mm and 8 mm). The lung simulator was ventilated with different combinations of PEEP (10,15 cmH20), tidal volume (240,420 ml), and respiratory rates (10,16,24b/min). PEEP and Tidal Volume were assessed both before suctioning and at the 15th second of the endotracheal suctioning manœuvre. Results: The median PEEP loss was -1.54 cmH2O (IQR: -5.93 to -0.59), and the median tidal volume loss was -153.91 ml (IQR: -213.92 to -100.35). Univariate analysis identified endotracheal tube diameter, tidal volume, and suction catheter diameter as significant factors influencing PEEP loss (p < 0.001), and multivariable analysis confirmed these associations (p < 0.001 for all variables). Suction catheter diameter was the only factor significantly associated with tidal volume loss (p < 0.001). Conclusions: Endotracheal tube diameter and tidal volume significantly influenced PEEP loss, and suction catheter diameter significantly influenced both PEEP and tidal volume loss during closed suctioning in simulated adults with ARDS. Implications for clinical practice: Results of this bench-top study suggest that, for adult patients with ARDS, the suction catheter should not exceed 50% of the inner diameter of the endotracheal tube, as recommended in the 1993 AARC guidelines. In this bench-top study, following the 2022 AARC recommendations led to a significant reduction in PEEP levels during endotracheal suctioning.