Closed suctioning preserved lung volume in ARDS, with unchanged oxygenation at 30 minutes

Design

Single-centre prospective randomised controlled trial with electrical impedance tomography

Population

60 mechanically ventilated ARDS patients on PEEP 5 to 10 cmH2O (30 open, 30 closed suction)

Primary outcome

Change in end-expiratory lung impedance and oxygenation after suctioning

Effect

Global impedance change at 1 minute -0.54 vs -2.32 (P < 0.001); SpO2 99.03% vs 98.07% (P = 0.007); oxygenation index at 30 minutes not different

In a single-centre randomised trial, 60 patients with ARDS on lung-protective, volume-controlled ventilation with PEEP of 5 to 10 cmH2O had open or closed endotracheal suctioning (30 each). End-expiratory lung impedance was tracked with electrical impedance tomography, with oxygen saturation and an arterial gas at 30 minutes.

The fall in global lung impedance was smaller with closed suction at 1 minute (-0.54 vs -2.32) and 10 minutes (-0.31 vs -1.14), both P below 0.001. Lung volume returned to baseline by 20 minutes after open suction but only at 30 minutes after closed suction. Saturation was lower after open suction at 1 minute (98.07% vs 99.03%, P = 0.007). The oxygenation index at 30 minutes, extubation and survival did not differ, and no adverse events were recorded.

The measures are physiological and short term, in a small trial with a surrogate imaging endpoint. It supports closed circuits as a sensible default where lung volume matters but does not show a difference in outcomes. In practice both techniques depend on the patient's PEEP and the need to disconnect.

• Use closed-circuit suction where available in ARDS to limit loss of lung volume.
• Keep suction passes brief and pre-oxygenate according to your unit protocol.
• Recheck saturation and ventilator pressures after suctioning in patients with severe hypoxaemia.
• Do not read this as showing better survival; the outcome data were not different.

Why it matters

It gives a bedside physiological reason for a common practice choice.

Don't overread it

A 60-patient single-centre trial with physiological endpoints; extubation and survival did not differ.

The statistics, in plain English

The impedance change is an index of lung volume lost, not a direct measure. Smaller loss at 1 and 10 minutes is a real physiological advantage, but with 60 patients and a 30-minute window, the trial cannot say whether it affects extubation or survival.

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