Three versus seven day circuit changes of humidified oxygen circuitry: a feasibility study

Abstract

Objective: The study compared the rate of humidifier acquired pneumonia between patients in whom humidifier circuitry is changed every three days with patients in whom circuitry is changed every 7 days in order to assess the feasibility of conducting a large scale randomised controlled trial to test the safety of extending the period between humidified circuit changes from three to seven days.

Design: The study was a randomised controlled trial.

Setting: The setting for the study was a 942 bed general teaching hospital in Queensland, Australia.

Subjects: The subjects of the study were patients receiving humidified oxygen in surgical, medical and infectious diseases units of the hospital.

Interventions: Consenting subjects were randomly allocated to either 3-day (control) or 7-day (intervention) circuit changes.

Main outcome measures: The primary outcome measure was nosocomial pneumonia and the secondary outcome measures were death and length of humidification therapy.

Results: Of the 51 eligible patients, 32 were included in the study (17 patients were randomised to the control group and 15 patients to the intervention group; recruitment rate 63%). During the study, four cases of nosocomial pneumonia occurred; two in the intervention group (13.3%) and two in the control group (11.8%) (χ2 = 0.018, p = 0.894). No patients died during the study period.

Conclusion: No high quality evidence exists to assist nurses to make a decision about how frequently to change humidifier circuitry. Potential cost savings involved in extending the time frame between humidifier circuitry changes indicate that a large scale randomised controlled trial is both feasible and important.