Lung recruitment manoeuvres are effective in regaining lung volume and oxygenation after open endotracheal suctioning in acute respiratory distress syndrome

Abstract

Introduction: Lung collapse is a contributory factor in the hypoxaemia that is observed after open endotracheal suctioning (ETS) in patients with acute lung injury and acute respiratory distress syndrome. Lung recruitment (LR) manoeuvres may be effective in rapidly regaining lung volume and improving oxygenation after ETS.

Materials and method: A prospective, randomized, controlled study was conducted in a 15-bed general intensive care unit at a university hospital. Eight consecutive mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome were included. One of two suctioning procedures was performed in each patient. In the first procedure, ETS was performed followed by LR manoeuvre and reconnection to the ventilator with positive end-expiratory pressure set at 1 cmH2O above the lower inflexion point, and after 60 min another ETS (but without LR manoeuvre) was performed followed by reconnection to the ventilator with similar positive end-expiratory pressure; the second procedure was the same as the first but conducted in reverse order. Before (baseline) and over 25 min following each ETS procedure, partial arterial oxygen tension (PaO2) and end-expiratory lung volume were measured.

Results: After ETS, PaO2 decreased by 4.3(0.9-9.7)kPa (median and range; P < 0.005). After LR manoeuvre, PaO2 recovered to baseline. Without LR manoeuvre, PaO2 was reduced (P = 0.05) until 7 min after ETS. With LR manoeuvre end-expiratory lung volume was unchanged after ETS, whereas without LR manoeuvre end-expiratory lung volume was still reduced (approximately 10%) at 5 and 15 min after ETS (P = 0.01).

Discussion: A LR manoeuvre immediately following ETS was, as an adjunct to positive end-expiratory pressure, effective in rapidly counteracting the deterioration in PaO2 and lung volume caused by open ETS in ventilator-treated patients with acute lung injury or acute respiratory distress syndrome.

Figure 1

Timeline of the study in minutes. The order of the two suctioning procedures α and β was randomized. The vertical lines above the timeline indicate blood gas samplings. ETS+LR, endotracheal suctioning followed by a lung recruitment manoeuvre; ETS-LR, endotracheal suctioning without a following lung recruitment manoeuvre; EELV, end-expiratory lung volume; LIP, lower inflection point; LR, lung recruitment manoeuvre; PEEP, positive end-expiratory pressure; PV, inspiratory pressure–volume curve.

Figure 2

Arterial partial oxygen tension (PaO₂), expressed as percentage of baseline, at time points before (baseline) and after the two endotracheal suctioning procedures. Endotracheal suctioning (●) with and (○) without a following lung recruitment manoeuvre. Values are expressed as means ± SEM (bars). *P < 0.05 between the two procedures, ^§P < 0.05, within the procedures between the measurements.

Figure 3

End-expiratory lung volume (EELV) expressed as percentage of baseline, at time points before (baseline) and after the two endotracheal suctioning procedures. Endotracheal suctioning (●) with and (○) without a following lung recruitment manoeuvre. Values are expressed as means ± SEM (bars). *P < 0.05 between the two procedures, ^§P < 0.01, within the procedures between the measurements.

Figure 4

Pressure volume–curves at baseline and at 25 min after the two procedures of endotracheal suctioning. The volumes are normalized to the absolute lung volume at an airway pressure of 17.5 cmH₂O at baseline. Values are expressed as means ± SEM (bars). ^#P < 0.05 between ETS-LR baseline curve and ETS-LR 25 min curve. ETS+LR, endotracheal suctioning followed by a lung recruitment manoeuvre; ETS-LR, endotracheal suctioning without a following lung recruitment manoeuvre.

Figure 5

Setup for the lung model for measurement of suction pressure. The test device consisted of a Plexiglas bottle with a connected water manometer. The endotracheal (ET) tube was inserted in the bottle through an opening at the top and the opening was sealed airtight thereafter. The tip of the suctioning catheter was introduced through the ET tube to 2 cm below the distal end of the ET tube. The catheter was then connected to a suction pressure of -400 mmHg at the wall inlet. The pressure generated in the bottle was measured as the difference between the water levels 'A' and 'B'.