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Biomedical subjects

M M Clay

Publications and source records attributed to M M Clay.

18 recordsLinked to original sources
PubMed1992

Time engaged in reading. A critical factor in reading achievement.

The reading achievement of deaf children may be low not only as a result of factors related to the hearing loss, such as a lag in language development. Environmental factors such as the quantity and quality of reading instruction, for example, may also cause low reading achievement. This study looked at the amount of time spent reading and the types of teacher interactions during reading instruction in classrooms at a school for deaf children and associated satellite classes in New Zealand. It was found that the deaf children spent very low levels of time engaged in reading and were subjected to teacher interactions that may inhibit the development of meaning-based reading skills. The quantity and quality of reading instruction for deaf children may differ from that experienced by most hearing children in New Zealand.

Audiovisual Aids↗
PubMed1990

Output characteristics of DeVilbiss No. 40 hand-held jet nebulizers.

DeVilbiss No. 40 hand-held nebulizers are widely used for quantifying airway responsiveness in large populations using pharmacological agents. We examined the aerosol characteristics of five nebulizers. Within each device, the aerosol output and droplet size were reasonably stable over a wide range of bulb pressures, although there were considerable differences in output characteristics between nebulizers. The droplet size was very large compared to conventional aerosol delivery systems, with a mass median diameter greater than 10 microns for three of the five devices. Between 28-50% of the output was in particles sufficiently small for airway deposition (less than 6.2 microns). A more vigorous compression of the bulb caused a small increase output and a reduction in droplet size, resulting in a much bigger variation in the output of the respirable aerosol (less than 6.2 microns) with changes in bulb pressure. The loss due to evaporation was about 3.5%, causing a similar rise in the osmolality of the nebulizer solution. In view of the variable nebulizer output and the marked between-operator variation in bulb pressure, the characteristics of individual DeVilbiss No. 40 nebulizers should be evaluated by individual operators before use in clinical practice or research.

Aerosols↗
PubMed1987

Effect of terbutaline administered from metered dose inhaler (2 mg) and subcutaneously (0.25 mg) on tracheobronchial clearance in mild asthma.

Tracheobronchial mucus clearance was measured in nine mild asthmatics, using an objective radioaerosol technique, on 3 separate days at intervals of 1 week. Immediately after radioaerosol inhalation, drug or placebo was administered via subcutaneous injection (SC) plus metered dose inhaler (MDI)--2 puffs. Three randomized treatments were used: saline placebo SC plus 2 mg terbutaline by MDI (1 mg per puff); 0.25 mg terbutaline SC plus placebo (propellants and surfactant only) by MDI; and double placebo. Changes in lung mucociliary clearance showed an inverse relationship to baseline clearance of both proximal and distal ciliated airways following inhaled terbutaline, whereas terbutaline SC related inversely only to baseline clearance of the distal ciliated airways. This may reflect the surface concentrations of drug, established by each route.

Administration, Inhalation↗
PubMed1987

Effect of nebulised aerosol size on lung deposition in patients with mild asthma.

A radioaerosol technique has been used to investigate whether the size distribution of aerosols released from a jet nebuliser affects the amount of aerosol delivered to the lungs. Six subjects with mild asthma (FEV1 81% of predicted) were studied on three occasions. On each visit they received one of three aerosols tagged with technetium-99m in 0.9% saline. The aerosols were generated by either (A) a Turret nebuliser operated at 8 l min-1 (mass median diameter (MMD) 1.8 micron); (B) an Upmist nebuliser operated at 6 l min-1 (MMD 4.6 microns); or (C) an Inspiron Mini-neb operated at 4 l min-1 (MMD 10.3 microns). The aerosols were given in a randomised single blind manner and inhaled under identical conditions of inspiratory volume and frequency. The mean (SD) percentage of aerosols A, B, C released from the nebulisers during inhalation that was recovered in an expiratory filter was 23 (6), 25 (4), and 24 (4) respectively. Of the aerosols released from the nebuliser and deposited in the body, the percentage deposited in the lung was 79 (3) for aerosol A, 59 (4) for aerosol B, and 44 (5) for aerosol C. The remaining aerosol was deposited in the oropharynx and swallowed. It is concluded that small nebulised aerosols (MMD less than 2 microns) deliver a larger dose to the lungs and should be used to maximise lung deposition.

Adult↗
PubMed1986

Effect of aerosol particle size on bronchodilatation with nebulised terbutaline in asthmatic subjects.

The bronchodilatation achieved by the beta 2 agonist terbutaline sulphate given as nebulised aerosol from different devices has been measured in seven patients with mild asthma (mean FEV1 76% predicted) over two hours after inhalation. The subjects were studied on four occasions. On three visits they received 2.5 mg terbutaline delivered from three different types of nebuliser, selected on the basis of the size distribution of the aerosols generated; and on a fourth (control) visit no aerosol was given. The size distributions of the aerosols expressed in terms of their mass median diameter (MMD) were: A: MMD 1.8 microns; B: 4.6 microns; C: 10.3 microns. The aerosols were given under controlled conditions of respiratory rate and tidal volume to minimise intertreatment variation. Bronchodilator response was assessed by changes in FEV1, forced vital capacity (FVC), peak expiratory flow (PEF), and maximal flow after expiration of 50% and 75% FVC (Vmax50, Vmax25) from baseline (before aerosol) and control run values. For each pulmonary function index all three aerosols gave significantly better improvement over baseline than was seen in the control (p less than 0.05) and had an equipotent effect on FEV1, FVC, and PEF. Aerosol A (MMD 1.8 microns) produced significantly greater improvements in Vmax50 and Vmax25 than did B or C (p less than 0.05). These results suggest that for beta 2 agonists small aerosols (MMD less than 2 microns) might be advantageous in the treatment of asthma.

Adult↗
PubMed1985

Evaluation of jet nebulisers for use with gentamicin solution.

Recently nebulised antibiotics (gentamicin and carbenicillin) have been used successfully to treat respiratory tract infection in patients with cystic fibrosis. No information exists, however, on the choice of nebuliser or the ideal mode of operation with antibiotic solutions, which are often viscous. The aerosol output, droplet size, and nebulisation time were assessed for four common brands of jet nebuliser (Bird, DeVilbiss, Inspiron, and Upmist) used to nebulise 2 ml (80 mg) and 4 ml (160 mg) of gentamicin solution (Garamycin, Kirby-Warrick) at four compressed gas flow rates (6, 8, 10, and 12 1 . min-1). There were considerable variations between the nebulisers, DeVilbiss and Upmist being most efficient in the release of respirable (less than 5 micron diameter) droplets. Droplet size and nebulisation time were inversely proportional to gas flow rate. Aerosol output and nebulisation time were increased by raising the volume fill from 2 to 4 ml, although nebulisation time could still be restricted to 12 minutes or less with DeVilbiss and Upmist at 12 1 . min-1. The output of drug in droplets of below 5 micron diameter ranged from 7.2 (SE 0.4) to 71.4 (4.3) mg, according to the type of nebuliser, flow rate, and volume fill. These studies suggest that for optimal drug delivery 4 ml gentamicin solution should be nebulised either at a fixed flow rate of 10-12 1 . min-1 or with a high flow compressor. Previous unsatisfactory clinical results with antibiotic aerosols may have been due in part to incorrect choice of nebuliser or inappropriate operating conditions, or both.

Aerosols↗
PubMed1985

Assessment of percussion, vibratory-shaking and breathing exercises in chest physiotherapy.

While gravity-assisted positions (postural drainage) and the forced expiratory technique are known to promote sputum clearance, the additional value of percussion, vibratory-shaking and breathing exercises individually in chest physiotherapy is uncertain. These modalities have been evaluated in 8 patients with copious sputum production (mean: 44 g/day), using an inhaled radioaerosol technique. Tracheobronchial clearance was unaffected by the addition of either vibratory-shaking or percussion with and without breathing exercises to postural drainage. There was however a significant (p less than 0.01) increase in the dry weight of sputum produced during each of these treatments. The combination of postural drainage used in conjunction with the forced expiration technique is responsible for the majority of mucus mobilisation and should form the basis of routine chest physiotherapy programmes; the other modes appear to be of lesser value.

Breathing Exercises↗
PubMed1983

Assessment of jet nebulisers for lung aerosol therapy.

The effect on nebuliser output of varying the flow rate of compressed air driving the device and the volume of respirator solution used was investigated in four brands of jet nebuliser. Raising the airflow rate from 4 to 6 1/min reduced the duration of nebulisation by approximately 40%, and a rise from 6 to 8 1/min reduced the duration by a further 15%. However, this change had only a slight effect on the proportion of the solution released. The volume of respirator solution placed in the nebuliser directly influenced the volume released as aerosol. After a 2 ml fill, less than 1 ml was released (50%). With a volume fill of 4 mg 60-80% was released, and with 6 ml 70-85% was released. Nebuliser output fell during nebulisation as the temperature of the solution dropped by 8-12 degrees C. A minimum 4 ml fill and an air-flow rate of 6 l/min are advocated to optimise nebuliser output.

Aerosol Propellants↗
PubMed1983

Factors influencing the size distribution of aerosols from jet nebulisers.

The size distribution of saline and bronchodilator (terbutaline) aerosol droplets generated from four widely used jet nebulisers (Acorn, Upmist, Turret, and Inspiron Mini-neb) has been measured with a Malvern 2200 Laser Particle Sizer. The mass median diameter of aerosol droplets generated by each nebuliser was strongly influenced by the driving flow rate of compressed air. By increasing the flow rate from 4 to 8 1 min-1 mass median diameters were halved (p less than 0.01) and there was an increase in the mass of aerosol within the optimum respirable range (less than 5 micron). To achieve this range the following individual flow rates were required: Turret 4 1 min-1, Acorn and Upmist 6 1 min-1, and Inspiron Mini-neb 8 1 min-1. A significant inverse relation (p less than 0.001) was found between mass median diameter and the geometric standard deviation, indicating that the aerosols were smaller but more heterodisperse at high flow rates. Changes in drug concentration had little effect on aerosol size. In 72% of the nebulisations followed to dryness there was no significant change in mass median diameter during the course of nebulisation and in the remainder it was less than 1.3 micron.

Aerosol Propellants↗