2004 OPEN FORUM Abstracts
ALBUTEROL DELIVERY USING THE DHD CIRCUVENT.
Terrence
O. Brady, RRT; Dean R. Hess, PhD, RRT, FAARC. Massachusetts
General Hospital and Harvard Medical School, Boston MA.
Background:
Inhaled albuterol is commonly administered to mechanically ventilated
patients. The CircuVent (DHD Healthcare) allows for delivery of
aerosolized medications without removing the heat-and-moisture
exchanger from the circuit.
Hypothesis: Albuterol delivery
through an endotracheal tube is affected by use of the CircuVent.
Methods: A Draeger Evita 4 ventilator was set to deliver a
tidal volume of 0.5 L, respiratory rate 12/min, flow of 30 L/min, and
inspiratory time 1 s. The circuit was attached to an endotracheal
tube (Mallinckrodt, 8 mm inner diameter), the distal end of which was
attached to a Puritan-Bennett D/Flex filter. The filter was attached
to a test lung with a compliance of 50 mL/cm H2O. A
Monaghan AeroVent spacer was placed into the ventilator circuit and a
pressurized metered-dose inhaler was actuated into the spacer
synchronized with the initiation of inhalation (4 actuations
separated by ≥ 30 s).
Albuterol was washed from the filter with 0.1 N NaOH and assessed for
albuterol by spectrophotometry at 243 nm. Albuterol was delivered
with and without the CircuVent in line, with a humidified circuit (35
C, 100% RH) and with a dry circuit. The CircuVent was set in the HME
bypass position. Each set of conditions was repeated in triplicate.
Results: Albuterol delivery was significantly less with use of
the CircuVent (P < 0.001). Albuterol delivery was also
significantly reduced with a wet circuit (P < 0.001). The most
efficient delivery was with a dry circuit and without the CircuVent.
Use of the CircuVent with a dry circuit (the usual configuration)
resulted in a reduction in delivered albuterol by about 40%.
Conclusions: Albuterol delivery by metered dose inhaler during
mechanical ventilation was decreased by use of the CircuVent. If the
CircuVent is used, it may be necessary to increase the dose to
achieve an equivalent therapeutic dose – our data suggests that
the dose should be doubled. These data should be subjected to
clinical study.
