Table 1

Effects of ETT obstruction and suction pressure

Open suction procedure
(ETT disconnected)
Before suctionModerate suctionMaximum suction
(cm H2O)
(cm H2O)
(cm H2O)
ETT 9Catheter 12 Fr0−0.5−1.5
Catheter 14 Fr0−1−2
Catheter 16 Fr0−2−3
Br.scope 16 Fr0−1.5−2
ETT 8Catheter 12 Fr0−1−2
Catheter 14 Fr0−2−4
Catheter 16 Fr0−3−7
Br.scope 16 Fr0−2−5
ETT 7Catheter 12 Fr0−2−5
Catheter 14 Fr0−4−10
Catheter 16 Fr0−9−23
Br.scope 16 Fr0−8−18
  • The effects of altered ETT diameter relative to suction devices and vacuum pressures during open suction procedure are shown. Pressures are measured distal to ETTs, with the ETT disconnected from the test model. Pressures did not change during 30 s of suctioning or when recording was repeated; pressure changes induced by moderate and maximum suction were significant for each permutation. 16 Fr catheters are normally not used clinically in ETT 7 mm ID, but the measurement is included for comparative reasons.

  • ETT, endotracheal tube.