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

Objectives: 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. Design: A bench test evaluation of simulated tracheal suction. Setting: Physiotherapy department of a major teaching hospital in Melbourne, Australia. Participants: Sixty-four nurses and physiotherapists who regularly apply TS to patients in the intensive care units of this hospital. Interventions: 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. Measurements and results: 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. Conclusion: 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.