Pulmonary Alveolar De-Recruitment – a cautionary tale of frivolous suctioning


set-up : clock, coke bottle, ETT, ballard suction device, suction source.

BEFORE : coke bottle (=2L of volume) – approximate the size of your lung.


AFTER : how long to suction 2L of air out of a closed system (totally FLATTENED)?  15 seconds.

In a nutshell :

Benefit : rids the lung of secretions.

Risk : may cause atelectasis to varied extents depending on the patient’s pulmonary status.

The risk : benefit ratio approaches unacceptable level of risk when the lung has a propensity to want to collapse.


The long winded version :

A long time ago, I read that when suction is initially applied on a closed system that has been connected since the last time the patient was suctioned, the initial insult of the “built-up suction back-pressure” (BUSBP) might be excessively high.

If the pressure had been set at -100cmH2O, the “built-up suction back-pressure” may be in the range of -250-300cmH2O.

Therefore, it was important to break the suction circuit before apply suction to the patient.

That article suggested / demonstrated that excessively negative pressures might collapse a lung.

In this case, the demo shows that a 2L coke bottle can be flattened in approximately 15seconds of normal continuous suctioning.

Most people I see suctioning are quick to suction the trachea but leave continuous suctioning on (~15 seconds) while they clear the line with NSS  (normal saline solution).


Situation : Patient sounds junky.

Background : Patient has been in the hospital for 2days post-op.  HD=2  POD=2

Assessment : Patient suctioned but “did not get anything.”

Recommendation : Start mucomyst.


Be wary of frivolous suctioning.