The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

AIRWAY RESISTANCE OVER TIME IN PATIENTS WITH HEAT AND MOISTURE EXCHANGERS AND HEATED HUMIDIFIERS

John S. Emberger, Francis Gott, Joel M. Brown, Melani Murphy; Respiratory Care, Christiana Care Health System, Newark, DE

BACKGROUND: We instituted widespread use of heat and moisture exchangers (HME) last year at our hospital. We use criteria published by Branson et. al.1 to determine heated humidifier (HH) versus HME use. We replace HME’s three times per week, or PRN for secretions in the HME. Several articles have demonstrated an increase in airway resistance (Raw) due to endotracheal tube lumen reduction over time with use of HME’s. We wanted to determine if there is a difference in Raw for our patients using HME’s versus HH over time. METHODS: An IRB approved retrospective evaluation of all mechanically ventilated patients was performed. Data collected included: type of humidification, duration of mechanical ventilation, calculated Raw every 8 hours. Respiratory care staff performs a measurement of Raw every 8 hours, with a plateau manuver. We analyzed adult patients that used only HME’s or only HH for the entire duration of mechanical ventilation from June 2008 to June 2009. We excluded patients that were switched from HME to HH and patients who were on a ventilator not capable of a square waveform for the Raw measurement. We analyzed Raw over time for patients on HME’s or HH’s for up to 10 days of use. RESULTS: We identified 796 patients that used HME’s exclusively during the entire time on mechanical ventilation and were on a ventilator capable of a square flow waveform. We identified 436 patients that used HH exclusively for the entire duration of mechanical ventilation and were on a ventilator capable of a square flow waveform. We excluded 477 patients who were switched between HME and HH. There was a stable trend in the average Raw over time up to 10 days for both the HME and HH patients. HME Raw was consistently about 2 cmH2O/L/sec higher than HH Raw which is expected because resistance of the HME itself. CONCLUSIONS: At our hospital in over 700 patients, we have a stable Raw trend in patients using HME’s for up to 10 days of use. We also note a stable Raw trend in over 400 patients using heated humidifiers for up to 10 days. Patients that meet our criteria for HME use do not show an increase in Raw for up to 10 days of use. REFERENCE: 1) Branson RD, Davis K, Campbell RS, Johnson DJ, Porembka DT. Humidification in the intensive care unit. Prospective study of a new protocol utilizing heated humidification and a hygroscopic condenser humidifier. Chest 1993;104(6):1800–1805. Sponsored Research - None

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