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.


Understanding cardiac physiology – putting it all together




It becomes glaring obvious what needs to be done.

The RV needs to be decongested.

The LV needs to be refilled.

We can do this many ways :

> give a pulmonary vasodilator –

via inhalational route : nitric oxide, Iloprost.

via intravenous route : milrinone (we’ll discuss later).

> oxygenate the pulmonary interstitum properly (increase FiO2).

> oxygenate the pulmonary interstitium and reverse HPV via alveolar recruitment maneuver (ARM).