Bennie McWilliams

Inhaled anti-inflammatory pharmacotherapy and subsequent hospitalizations and emergency department visits among patients with asthma in the Texas Medicaid program.

BACKGROUND Rates of asthma-related hospitalizations and emergency department (ED) visits continue to rise in the United States. The National Asthma Education and Prevention Program recommends the use of controller pharmacotherapy for patients with persistent asthma. OBJECTIVE To investigate the influence of initiating inhaled anti-inflammatory (IAI) pharmacotherapy following an asthma-related hospitalization or ED visit on risk of subsequent morbid events. METHODS Texas Medicaid asthma-related medication and medical services claims for September 1997 to July 2001 were extracted. An asthma-related morbid event served as the index event (ED visit or hospitalization for cohort 1; hospitalization for cohort 2). Members of both cohorts were then followed up until a subsequent morbid event occurred or until 1 year after index. Logistic regression was used to compare patients who used IAI medication within 100 days following their index event with nonusers. RESULTS Controlling for demographic and resource use variables, there was a 52% reduction in the risk of a subsequent ED visit or hospitalization in the year following the index event among users of IAI medication within cohort 1 (risk ratio [RR], 0.485; 95% confidence interval [CI], 0.416-0.565; P < .001). There was a 61% reduction in the risk of a subsequent hospitalization among users of IAI medication within cohort 2 (RR, 0.393; 95% CI, 0.284-0.545; P < .001). CONCLUSIONS Less than half of the patients had a prescription claim for an IAI medication within 100 days following their index event. Patients who received these medications had a lower risk of a subsequent asthma-related morbid event for the next year.

Therapeutic aerosol delivery during mechanical ventilation

Objective To provide an overview of aerosol drug delivery during mechanical ventilation in the pediatric and adult populations. Data Sources Published articles and abstracts identified in a MEDLINE search (1984–July 1994) were reviewed. Study Selection All articles and abstracts found, including review articles, in vivo and in vitro studies, case reports, and case series pertaining to issues involving aerosol delivery during mechanical ventilation, were reviewed. No predetermined selection criteria were used to exclude studies. Data Extraction Percent delivery of the starting dose to either the patients or the various in vitro lung models, as well as each variable possibly affecting delivery for each study, were tabulated for each study reviewed. Data Synthesis The delivery of therapeutic aerosols to endotracheally intubated and mechanically ventilated patients presents a unique challenge for healthcare providers. Delivery can be affected by the diameter of the endotracheal tube and ventilator circuitry, type of ventilator, ventilator modes, type of delivery device, and how the delivery device is operated and introduced into the ventilator circuitry. The drug being aerosolized may behave differently from one delivery system to another. The proper operation of each device requires attention to positioning in the ventilator circuit as well as the mode of ventilation. Conclusions No apparent advantage exists for metered-dose inhalers with a large-volume adapter over jet nebulizers, as each method of delivery is capable of similar efficiency (5–15%). Sufficient attention to detail, including the use of an efficient nebulizer and/or adapter and proper placement and operating method, is required to provide optimal delivery. For bronchodilator administration, careful monitoring of outcomes will provide the most optimal dosing schedule.

Pulmonary ventilatory function decreases in proportion to increasing altitude

The objective of this study was to examine how pulmonary ventilatory function, including response to bronchodilation, is related to altitude during high-altitude trekking. This cohort experiment consisted of multiple spirometric tests before and after bronchodilation in participants at baseline (1624 m) and at different altitudes (3404-4896 m) during a 2-week trek. The setting was in the Himalayas. Eleven men (ages 22-68 years) and eight women (ages 19-42 years) participated. Interventions were at altitudes of 1624 m to 5265 m; albuterol was administered via Rotahaler. Forced vital capacity (FVC) decreased by an average of 3.8% [95% confidence interval (CI) 1.6 to 6.0] per 1000-m altitude increment. Forced expiratory volume in 1 second (FEV1.0) decreased 3.7% (95% CI 1.9 to 5.5) per each 1000-m altitude increment. Maximal midexpiratory flow rate (FEF25-75%) decreased by 3.6% (95% CI 0.9 to 6.3) per each 1000-m altitude increment. Small, postalbuterol flow increases were present at baseline and at altitude. Ventilatory function returned quickly toward baseline upon descent. One trekker developed cough, dyspnea at rest, extreme weakness, rales, tachycardia, and oxygen desaturation to 71%. His ventilatory measurements did not differ significantly (p > 0.32) from the group means. We concluded that changes in some pulmonary ventilatory parameters (FVC, FEV1.0, and FEF25-75%) were proportional to the magnitude of altitude during a high-altitude trek. These were tolerated well and do not seem to relate to acute mountain sickness. A bronchodilator effect was not increased at altitude.

Comparison of Two Methods of Delivering Continuously Nebulized Albuterol

OBJECTIVE To compare the relative delivery of 2 methods for providing continuously nebulized albuterol (CNA): a small-volume nebulizer plus infusion pump versus a large-volume nebulizer. DESIGN An open, randomized comparison of 3 hours of CNA administration using an in vitro lung model with a follow-up particle size assessment of the large-volume nebulizer. METHODS Six different nebulizers of each type were connected to a lung model via a volume-limited mechanical ventilator and infant ventilator circuitry. Albuterol was nebulized at 10 mg/h for 3 hours in random order. The small-volume nebulizer used was the Airlife Misty Neb (Baxter, Valencia, CA); the large-volume nebulizer was the HEART Nebulizer (Vortran Medical, Orangevale, CA). One large-volume nebulizer was operated over 8 hours for the output and particle sizing study. RESULTS The small-volume nebulizer delivered a greater amount of albuterol (mean ± SD percentage of total nebulized) to the model lung (5.75 ± 1.38% vs. 4.12 ± 0.67%; p < 0.025) than the large-volume nebulizer, but demonstrated greater variability. Although total output was not maintained after 8 hours of nebulization with the large-volume nebulizer, the percent of particles in the respirable range remained consistent. CONCLUSIONS The large-volume nebulizer evaluated in this study maintains consistent output up to 8 hours and provides an acceptable method for delivering CNA through an infant ventilator circuit.

Rate‐Adaptive Cardiac Pacing in Children Using a Minute Ventilation Biosensor

YABEK, S.M., ET AL.: Rate‐Adaptive Cardiac Pacing in Children Using a Minute Ventilation Biosensor.Chronotropic integrity is required for a normal cardiac output response to exercise. We evaluated a rate‐adaptive ventricular demand pacemaker (Telectronics, META‐MV) which uses minute ventilation as the sensed physiological variable for adjusting pacing rate, in seven young patients with a mean age of 11.4 years. All patients had clinically significant bradycardia related to complete heart block (n = 4) or sinus node dysfunction (n = 3). For the entire group, paced heart rates increased from 70 ± 10 beats/min to 151 ± 19 beats/min with exercise testing. The onset of rate adaptation took < 30 seconds. Changes in paced rate were linearly related to workload, VO2 (5.9 to 20.7 mL/min/kg) and minute ventilation (8–65 L/min). The decline in pacing rate after exercise was related directly to the gradual decrease in minute ventilation and VO2. Our data show that minute ventilation closely and accurately reflects the metabolic demands of varying workloads in children and can be used to achieve physiological, rate‐adaptive pacing.

Effective once-daily administration of budesonide inhalation suspension by nebulizer with facemasks or mouthpieces for persistent asthma in infants and young children

This study is a retrospective analysis comparing nebulized budesonide inhalation suspension (BIS; Pulmicort Respules™, AstraZeneca, Wilmington, DE) administered once daily by facemask or mouthpiece...

Aerosolized beta2-agonists do not induce bronchial hyperreactivity in healthy adults

Objective: To determine whether regular administration of beta2 agonists could induce bronchial hyperreactivity in nonasthmatic volunteers. Design: A prospective, randomized, double-blind, placebo-controlled, crossover clinical trial of 2 weeks therapy with a 2-week washout period between each treatment period. Treatments were albuterol or matching placebo as 2 inhalations 4 times daily. Subjects: Ten healthy, nonsmoking women 27—37 years old. Setting: General clinical research center of a tertiary care university hospital. Main Outcome Measures: Baseline spirometry and methacholine bronchoprovocation studies were performed immediately prior to, 12 hours following, and 1 and 2 weeks following each treatment period. Results: No change was detected in either baseline spirometry or methacholine responsiveness. Conclusions: This suggests that if beta2-agonists induce a rebound bronchial hyperreactivity, it is not the result of the production of tolerance or a direct effect on bronchial smooth muscle.

Effects of theophylline on inhaled methacholine and histamine in asthmatic children

The effects of a therapeutic serum theophylline concentration on inhaled methacholine and histamine were studied in 8 stable, moderately severe asthmatic children 8 to 15 yr of age. Placebo or theophylline in a hydroalcoholic solution was administered in a double-blind fashion, and standard histamine and methacholine challenges were performed following both placebo and theophylline. Serum theophylline concentration averaged 13 mg/L (range 4.0 to 22.1). Theophylline caused a significant increase (p less than 0.01, paired t test) in provocative dose for a 20% drop in FEV1 (PD20 FEV1) for both methacholine (from a mean of 19.1 to 57.5) and histamine (75.9 to 144.5). This effect did not correlate with the small (7.6% increase in FEV1) but significant bronchodilatation produced by theophylline. We conclude that theophylline in doses that achieve serum concentrations in the usual therapeutic range produces significant attenuation of the bronchoconstrictor response to methacholine and histamine challenges in asthmatic children. The mechanism and therapeutic implications of this remain undefined.