The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

HEAT MOISTURE EXCHANGERS FOR POST-OP OPEN HEART PATIENTS; IS THERE A DIFFERENCE?

Alden Fletcher M.D., phD., Siavosh Khonsari M.D., John Cefaratt B.S., R.R.T., Kaiser Permanente, Los Angeles Medical Center, Cardiac Surgical Unit

INTRODUCTION: Heat Moisture Exchangers (HMEs) have been utilized for several years in the hospital setting for humidification of mechanically ventilated patients. To date there have been few reported studies of their use in Open Heart patients post operatively. In 1992 we conducted a six month product evaluation of an HME on elective coronary artery by-pass graft (CABG) patients. We evaluated retrospectively and compared the effects of an HME to a conventional humidifier by monitored cardiac and respiratory function. The focus was on secretion characteristics, pulmonary capillary wedge pressure (PCWP) and work of breathing (WOB). 44 patients, (39 males, 5 females) met criteria for the evaluation, 22 in each group. Both groups were similar in age, smoking history and baseline characteristics. METHOD: The product evaluation was conducted on the Pall BB-50T HME and compared to the Conchatherm III plus. Patient criteria was to be over 16 years of age, have no pre-existing lung disease and had elective CABG. The airway was primed with 10ccs of normal saline before inserting the HME. Pulmonary mechanics, cardiac function and secretion characteristics were observed for changes in secretion amount, color and consistency, increased (WOB) and decreased (PCWP). Data was collected and analyzed by our statisticians using Fisher's Exact., Stuart & Maxwell and McNemer tests. Results: After review it was noted that only 2 subsets of the variables had a p < 0.05 PCW pre-HME, was higher in the study group and secretion consistency pre-study was higher in the control group. All other variables had no statistically significant difference. Intubation time and length of stay was similar for both groups. It was noted that for the time patients were intubated only one HME was needed as was one humidifier column and bottle of water.

Variable Study Group Control Group p Value

PCWP pre/post 13.09/14.23mmHg 9.86/15.29mmHg 0.005/0.479

WOB pt/vent. 0.15j/1.71j 0.29j/1.46j 0.054/0.097

Sec.amt. pre/post 14.3%/36.4% 33.3%/50.0% 0.147/0.361

Sec.color pre/post 33.3%/36.4% 9.5%/31.8% 0.130/0.747

Sec.Cons. pre/post 57.1%/59.1% 23.8%/54.5% 0.028/0.761

DISCUSSION: During mechanical ventilation adequate humidification has an important effect on pulmonary secretions. In this study we observed no adverse effects on pulmonary or cardiac function nor was there any significant change in the quantity or characteristics of pulmonary secretions. Our first day cost to use an HME was 70% less than the conventional humidifier setup. CONCLUSION: Despite the fact that in some cases HMEs provide less than 100% relative humidity, we found that there was no significant differences between the use of HMEs and conventional humidifiers for post-op open heart patients with regards to secretion characteristics, cardiac function and WOB. This study shows that HMFs can be used effectively for most open heart patients and at a reduced cost saving.

Reference: OF-96-001

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