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1.  Effect of a spacer on pulmonary aerosol deposition from a jet nebuliser during mechanical ventilation. 
Thorax  1995;50(1):50-53.
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.
PMCID: PMC473707  PMID: 7886649
2.  Lung deposition of nebulised pentamidine in children. 
Thorax  1993;48(3):220-226.
BACKGROUND: Nebulised pentamidine is effective for preventing Pneumocystis carinii pneumonia in adults with acquired immunodeficiency syndrome. The nebuliser dose required to produce equivalent lung concentrations of pentamidine in children is unknown. This study was performed to measure pulmonary pentamidine deposition in children and to relate this to age, ventilation pattern, and body size. METHODS: Nebulised pentamidine (50 mg in 6 ml saline) was administered to 12 children (including one with lymphocytic interstitial pneumonitis) and to six adults with human immunodeficiency virus infection using a Respirgard II nebuliser. Technetium-99m labeled colloidal human serum albumin was used as an indirect marker for pentamidine and deposition in the lungs was detected by a gamma camera. RESULTS: Absolute deposition of pentamidine was not related to age, height, weight, spirometry, or ventilation characteristics. Deposition, as a mean (SD) percentage of nebuliser output, was similar in children aged 8-11 years (5.5(2.4)%), teenagers aged 12-15 years (7.2(2.2)%) and adults (7.1(2.6)%). Aerosol concentration within the lungs (% nebuliser output deposited/predicted total lung capacity) was therefore higher in children (1.9(1.5)%/1) and teenagers (1.9(0.7)%/1) than in adults (1.0(0.7%)/1), and was negatively correlated with height (r = -0.69) and weight (r = -0.50). Deposition of aerosol in the region of the large central airways was particularly marked in children. Small reductions in forced expiratory volume in one second and forced vital capacity after treatment did not differ significantly between adults and children and visual analogue scores of subjective adverse effects did not vary with age. CONCLUSIONS: These results suggest that children probably require lower nebuliser pentamidine doses to produce lung pentamidine concentrations equivalent to those found to be effective for preventing P carinii pneumonia in adults using the Respirgard II nebuliser.
PMCID: PMC464357  PMID: 8497819
3.  Pulmonary deposition of nebulised amiloride in cystic fibrosis: comparison of two nebulisers. 
Thorax  1991;46(10):717-721.
BACKGROUND Preliminary evidence suggests that regular inhalation of nebulised amiloride reduces sputum viscoelasticity, increases the clearance of sputum by mucociliary mechanisms and by coughing and reduces the rate of deterioration in lung function in patients with cystic fibrosis. These effects depend on adequate delivery of amiloride to the airways. This study was performed to quantify and compare pulmonary deposition of amiloride produced by two different nebuliser systems. METHODS The pulmonary deposition of nebulised amiloride (1 mg in 3 ml saline) was measured in eight patients with cystic fibrosis when given via a jet (System 22 with CR 60 compressor) and an ultrasonic (Fisoneb) nebuliser. Human serum albumin labelled with technectium-99m was used as an indirect marker for amiloride and its deposition in the lung was detected with a gamma camera. RESULTS Amiloride inhalation caused no side effects or changes in spirometric indices. The mean (SD) total pulmonary amiloride deposition was 57 (24) micrograms with the System 22 and 103 (53) micrograms with the Fisoneb nebuliser. Pulmonary deposition was completed more rapidly with the Fisoneb (4-5 minutes) than with the System 22 nebuliser (7-8 minutes) and the Fisoneb was preferred by the patients. CONCLUSIONS Both nebulisers appeared to deliver adequate amounts of amiloride to the lungs, but treatment with the Fisoneb nebuliser was quicker, more efficient, and more acceptable to the patients. Of the two nebulisers assessed, the Fisoneb would be preferred for clinical trials.
PMCID: PMC463390  PMID: 1750018
4.  Pulmonary deposition of a nebulised aerosol during mechanical ventilation. 
Thorax  1993;48(2):154-159.
BACKGROUND: There is increasing use of therapeutic aerosols in patients undergoing mechanical ventilation. Few studies have measured aerosol delivery to the lungs under these conditions with adequate experimental methods. Hence this study was performed to measure pulmonary aerosol deposition and to determine the reproducibility of the method of measurement during mechanical ventilation. METHODS: Nine male patients were studied during mechanical ventilation after open heart surgery and two experiments were performed in each to determine the reproducibility of the method. A solution of technetium-99m labelled human serum albumin (99mTc HSA (50 micrograms); activity in experiment 1, 74 MBq; in experiment 2, 185 MBq) in 3 ml saline was administered with a Siemens Servo 945 nebuliser system (high setting) and a System 22 Acorn nebuliser unit. Pulmonary deposition was quantified by means of a gamma camera and corrections derived from lung phantom studies. RESULTS: Pulmonary aerosol deposition was completed in 22 (SD 4) minutes. Total pulmonary deposition (% nebuliser dose (SD)) was 2.2 (0.8)% with 1.5% and 0.7% depositing in the right and left lungs respectively; 0.9% of the nebuliser activity was detected in the endotracheal tube or trachea and 51% was retained within the nebuliser unit. Considerable variability between subjects was found for total deposition (coefficient of variation (CV) 46%), but within subject reproducibility was good (CV 15%). CONCLUSIONS: Administration of aerosol in this way is inefficient and further research is needed to find more effective alternatives in patients who require mechanical respiratory support. This method of measurement seems suitable for the assessment of new methods of aerosol delivery in these patients.
PMCID: PMC464293  PMID: 8493630
6.  Alveolar permeability in HIV antibody positive patients with Pneumocystis carinii pneumonia. 
Genitourinary Medicine  1987;63(4):268-270.
Pulmonary permeability was assessed using the technique of 99mTc (technetium-99m) diethylene triamene pentacetic acid (DTPA) aerosol transfer in 10 patients who had antibodies to human immunodeficiency virus (HIV) and were non-smokers and in 20 HIV antibody positive smokers. Five patients had Pneumocystis carinii pneumonia (PCP) proved by transbronchial lung biopsy; four were non-smokers and one a smoker. Two findings emerged: patients with PCP had greater epithelial permeability than non-smokers and smokers; and the permeability curves were monophasic in smokers and non-smokers, but biphasic in patients with PCP. The biphasic curve observed is indicative of diffuse alveolar damage and might be useful to predict PCP in patients with antibodies to HIV who have normal chest radiographs. As the study was of only five patients with PCP, however, further studies are necessary to confirm this observation.
PMCID: PMC1194081  PMID: 3308684

Results 1-6 (6)