Setting safe and effective suction pressure: the effect of using a manometer in the suction circuit

To establish the levels of pressure used to perform tracheal suction (TS) and if they are affected by having a manometer visible in the suction circuit.

A bench test evaluation of simulated tracheal suction.

Physiotherapy department of a major teaching hospital in Melbourne, Australia.

Sixty-four nurses and physiotherapists who regularly apply TS to patients in the intensive care units of this hospital.

All subjects used both circuit A (without a visible manometer) and B (with a visible manometer) in a predetermined random order. For both, subjects adjusted the suction control tap to where they said a safe and effective pressure (set pressure) was delivered and then occluded the suction catheter as though suctioning (applied pressure). Subjects then completed a questionnaire on their current TS practise.

All set pressures (mean = 228.57 mmHg) and all applied pressures (mean = 359. 52 mmHg) were significantly higher (P <.001) when compared to the expected pressures (mean = 135 mmHg). Pressures set without a visible manometer (circuit A) were significantly higher (P <.05) than those using a visible manometer (circuit B) but the applied pressures were not significantly different (P =.166). Neither the investigator (P =.618) or the test order (P =.167) had a significant effect on the outcome. Questionnaire results showed 31 % of subjects considered 100-170 mmHg a safe and effective suction pressure whilst none reported using an objective means of measuring pressure.

All pressures in both circuits were significantly higher than those recommended as safe in the literature. In addition, pressures were unaffected by the inclusion of a visible manometer in the suction circuit.