The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

EVALUATION OF WATER ACCUMULATION IN THE HEALTHSCAN OPTIVENT^{TM}, DHD ACE^{(R)}, MONAGHAN AERO VENT^{(R)} METERED DOSE INHALER SPACERS UNDER NORMAL MECHANICAL VENTILATION CONDITIONS.

Jonathan B. Waugh, Ph.D., RRT, John B. Waugh, BA, Joseph L. Rau, Jr., Ph.D., RRT Cardiopulmonary Care Sciences Department, GA State University, Atlanta, GA

Introduction: Clinicians attempt to minimize contamination of a patient's airways by reducing the frequency of opening the ventilator circuit. Metered dose inhaler (MDI) spacers are now designed to be left in the ventilator circuit between drug administrations, which raises the question; how much fluid accumulates and is it a safety concern? Methods: We measured distilled water accumulation in three brands of MDI spacers (OptiVent, ACE, AeroVent) at 0, 30, and 45 degree positions at 4 and 8 hour time intervals. Water accumulation was measured by the difference in Pre-test (dry) weight and post-test (wet) weight, using the same ventilator, circuit, humidifier (Fisher & Paykel MR480), and test lung with a room temperature range of 71-73° F and relative humidity range of 59-63%. Results:

Position Grams of Water Increase at:

Spacer Brand (degrees) 4 Hours 8 Hours

OptiVent 0 4.641 9.520

AeroVent 0 1.046 1.079

ACE 0 10.570 23.141

OptiVent 30 1.782 1.785

AeroVent 30 0.673 0.825

ACE 30 6.503 8.049

OptiVent 45 1.582 1.578

AeroVent 45 0.598 0.681

ACE 45 5.300 6.561

Conclusions: In the angled positions, both the OptiVent and AeroVent spacers accumulated "clinically" insignificant amounts of fluid over both 4 and 8 hour periods of use (less than 5 ml). All three spacers can be left in line with ventilated subjects however the OptiVent and ACE did not require manipulation to open the chamber in order to be used with an MDI canister. Determining if infection rates are influenced by leaving spacers in line or removing them between treatments would be a useful next step in the investigation of these devices.

OF-97-065

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