PT  - JOURNAL ARTICLE
AU  - Harvey, C J
AU  - O'Doherty, M J
AU  - Page, C J
AU  - Thomas, S H
AU  - Nunan, T O
AU  - Treacher, D F
TI  - Effect of a spacer on pulmonary aerosol deposition from a jet nebuliser during mechanical ventilation.
AID  - 10.1136/thx.50.1.50
DP  - 1995 Jan 01
TA  - Thorax
PG  - 50--53
VI  - 50
IP  - 1
4099  - http://thorax.bmj.com/content/50/1/50.short
4100  - http://thorax.bmj.com/content/50/1/50.full
SO  - Thorax1995 Jan 01; 50
AB  - BACKGROUND--Several factors have been identified which improve nebulised aerosol delivery in vitro. One of these is the addition of a spacer to the ventilator circuit which improves aerosol delivery from a jet nebuliser to a model lung by approximately 30%. The current study was designed to demonstrate whether similar improvements could be demonstrated in vivo. METHODS--Ten patients (seven men) were studied during mechanical ventilation (Siemens Servo 900C) after open heart surgery. Aerosol was delivered using a Siemens Servo 945 nebuliser system (high setting) driving a System 22 Acorn jet nebuliser (Medic-Aid) containing 3 ml technetium-99m labelled human serum albumin (99mTc-HSA (50 micrograms); activity in the first nebulisation, 90 MBq; in the second nebulisation, 185 MBq). Central and peripheral lung aerosol deposition and the time to complete deposition were measured using a gamma camera and compared when the nebuliser was connected to the inspiratory limb using a simple T-piece or a 600 ml spacer. RESULTS--The addition of the spacer increased total lung deposition (mean (SD) percentage initial nebuliser activity) from 2.2 (0.7)% to 3 (0.8)%. There was no difference in the time required to complete nebulisation (18.2 min v 18.3 min respectively for T-piece and spacer) or in the retention of activity in the nebuliser (46.2% v 47.1% respectively). CONCLUSIONS--The combination of a spacer with a jet nebuliser increased lung deposition by 36% in mechanically ventilated patients and is a simple way of increasing drug deposition or reducing the amount of an expensive drug required for nebulisation.