Bedside detection of retained tracheobronchial secretions in patients receiving mechanical ventilation: is it time for tracheal suctioning?

Objective: To identify parameters that indicate retained secretions and the need for tracheal suctioning (TS) in patients receiving mechanical ventilation (MV).
Design: Prospective observational study.
Setting: A 14-bed medical ICU in a 946-bed university hospital.
Patients: Sixty-six consecutive patients receiving MV.
Interventions: Two successive tracheal suctions, TS1 and TS2, performed at a 2-h interval as usual patient care. Retained secretions were considered significant if the volume of secretions removed by TS2 was > 0.5 mL.
Measurements and Results: Variations between TS1 and TS2 of pulse oximetric saturation (SpO(2)), peak inspiratory pressure (Ppeak), tidal volume (VT), and Ramsay score were compared between patients with TS2 < or = 0.5 mL (group 1; n = 27) and patients with TS2 > 0.5 mL (group 2; n = 39). The presence of a sawtooth pattern on flow-volume loop displayed on the monitor screen of the ventilator and of respiratory sounds heard over the trachea before TS2 were compared between the two groups. Variations of Ppeak, VT, SpO(2), and Ramsay score between TS1 and TS2 did not differ between the two groups. However, group 2 had a sawtooth pattern (82% vs 29.6%; p = 0.0001) and respiratory sounds (66.6% vs. 25.9%; p = 0. 001) more frequently than group 1 before TS2. For the sawtooth pattern, the likelihood ratio (LR) of a positive test was 2.70 and the LR of a negative test was 0.25, while for respiratory sounds it was 2.50 and 0.45, respectively. When the presence of a sawtooth pattern and of respiratory sounds was combined, the LR of a positive test rose to 14.7 and the LR of a negative test was 0.42.
Conclusions: A sawtooth pattern and/or respiratory sounds over the trachea are good indicators of retained secretions in patients receiving MV and may indicate the need for TS. Conversely, the absence of a sawtooth pattern may rule out retained secretions.