Pulmonary function tests leading to the diagnosis of vascular ring in an infant

A 5-month-old baby was referred to our pulmonary clinic because of chronic cough and wheeze, unresponsive to antiasthmatic treatment. Examination in the Infant Pulmonary Function Laboratory suggested an upper airway obstruction. An aberrant right subclavian artery was subsequently confirmed by a barium swallow, flexible bronchoscopy, and an angiographic reconstructed chest CT study. Due to modest symptoms a conservative medical approach was taken. At follow-up 1 year later, the patient had fewer respiratory and gastrointestinal symptoms.

Beta-agonist aerosol distribution in respiratory syncytial virus bronchiolitis in infants

Bronchodilator aerosols are frequently administered to infants with bronchiolitis but with little success. The efficacy of aerosol treatments depends mainly on adequate targeting of the aerosol particles to the inflamed airways. This study evaluated the lower respiratory tract distribution characteristics of nebulized bronchodilators in infants with acute bronchiolitis.

METHODS

Twelve infants (mean age +/- SD, 8 mo +/- 4 mo) who were admitted for acute respiratory syncytial virus bronchiolitis were treated with (99m)Tc-albuterol aerosol. Gamma-scintigraphy was used to assess total body and lung deposition as well as pulmonary distribution of the medication.

RESULTS

Of the total 6-min nebulized dose (i.e., drug aerosol dose leaving the nebulizer [not the nebulizer charge]), 1.5% +/- 0.7% reached the right lung, with only approximately one third of that (0.6%) penetrating to the peripheral lung zone. There was 7.8% +/- 4.9% deposition in the upper respiratory and gastrointestinal tracts and 10%-12% remained on the face. No correlation was found between any of the deposition indices and the clinical response data or any of the demographic parameters (e.g., height, weight, body surface area, or clinical score).

CONCLUSION

Poor total aerosol deposition in infants may be related as much to their small conducting airways as to the disease state. There is considerable room for improvement in aerosol delivery in this age group, with greater emphasis on targeting narrowed peripheral airways with superfine aerosols.

Aerosol therapy with valved holding chambers in young children: importance of the facemask seal

OBJECTIVE

Masks are an essential interface between valved holding chambers (VHCs), or spacers, and a small child's face for providing aerosol therapy. Clinical experience suggests that many young children do not cooperate with the VHC treatment or tolerate a mask of any kind. This might impair the mask-face seal and reduce the dose delivered to the child. The objective of this study was to evaluate the ability of parents to provide a good mask-face seal in infants and toddlers using 3 masks provided with commonly used pediatric VHCs and compare this with the seal obtained with the Hans Rudolph pediatric anesthesia mask.

METHODS

A preliminary in vitro filter study was conducted to validate the assumption that reduced ventilation as a result of increased facemask leak reduces the drug aerosol dose delivered to the mouth. Facemask leak then was studied in vivo for NebuChamber, AeroChamber, BabyHaler, and Hans Rudolph masks by measuring ventilation with an in-line pneumotachograph while the facemask was held in place by experienced parents who were asked to demonstrate how they deliver medication to their children without any additional instruction. Thirty children (mean age: 3.2 +/- 1.4 years) performed 4 repeat studies with each mask. The first 10 patients performed the tests once again within 1 month. On the second occasion, the parents were coached continuously and encouraged to hold the mask tightly against the child's face.

RESULTS

The AeroChamber and Hans Rudolph masks provided the best seal as reflected in the magnitude of the ventilation measured through them. The NebuChamber provided the poorest seal, with 45% less ventilation than the AeroChamber and Hans Rudolph masks. There was considerable intraindividual variability for all masks (24% to 48%); however, the variability with the NebuChamber mask was 2-fold greater than the other masks. All ventilatory volumes during the coached session were significantly greater than during the uncoached session. Variability during the coached session was significantly less (except for the BabyHaler, which remained unchanged).

CONCLUSIONS

VHCs with masks designed for use with small children may provide a poor seal with the face, leading to reduced or more variable dose delivery. The facemask seal is critical for efficient aerosol delivery to infants and young children, and this should be stressed to parents.

Methacholine-induced temporal changes in airway geometry and lung density by CT

PURPOSE

Electron-beam CT (EBCT) was utilized to assess the time course of changes in airways cross-sectional area (CSA) and lung density during methacholine-induced bronchoconstriction.

MATERIALS AND METHODS

EBCT scans (200 ms, 3-mm thickness, 2 mm increments) were obtained before (baseline) and 30 s, 2 min, and 4 min after bolus IV injection of methacholine to pigs receiving mechanical ventilation. A total of seven experiments were analyzed using custom-made image analysis software. With each challenge, five different airways and 50 lung regions of interest were studied.

RESULTS

The time course of lung density changes paralleled the time course for CSA changes. The maximal response to methacholine, measured in terms of both CSA and lung density changes, occurred 30 s after injection. Lung density changes were unaffected by reconstruction algorithm, normal (standard) or sharp (high resolution). Overall, there was increased air content in the lung during bronchoconstriction. This effect was significantly greater at the dependent lung regions.

CONCLUSIONS

EBCT is an effective tool to assess temporal and regional changes in the lung during bronchoconstriction. Measurements of lung density during bronchoconstriction allow for assessment of peripheral changes that are beyond the CT spatial resolution of airways anatomy.

Physiological and practical evaluation of a biological/chemical protective device for infants

The Chemical Infant Protective System (CHIPS) is a special hood-like system into which a small battery-operated blower delivers filtered air. Because it is a semiclosed system, there is a risk of dangerous CO2 accumulation within the device, which particularly affects infants with acute or chronic respiratory disorders. Eleven infants hospitalized with various respiratory illnesses wore the device for 15 minutes. Inspired O2, inspired CO2, heart rate, respiratory rate, oxygen saturation, and inside temperature and humidity were measured before and during this test period. Inspired O2 and heart rate during the test period were significantly lower than baseline levels (O2, 19.1 vs. 20.1%; heart rate, 133 vs. 142 beats/min). Inspired CO2 and inside temperature during the test period were significantly higher than baseline levels (CO2, 0.23 vs. 0.06%; temperature, 25.0 vs. 23.1 degrees C). Oxygen saturation, respiratory rate, and humidity were not different from baseline levels. A short-term stay within the CHIPS in well-ventilated surroundings did not result in significant clinical and physiological impact for sick infants. Nevertheless, trends were identified that may be worrisome during longer periods and in sealed rooms.

Metered-dose inhaler accessory devices in acute asthma: efficacy and comparison with nebulizers: a literature review

OBJECTIVES

To evaluate the current literature about the efficacy of providing inhaled medications by metered-dose inhalers and accessory devices (MDI/ADs) to children with acute asthma and to compare it with the current standard of care, small-volume nebulizers (SVNs).

DATA SOURCES

Online computer and manual searches in English-language journal articles published between 1980 and 1996.

STUDY SELECTION

Seventeen prospective clinical trials that have used MDI/ADs in the treatment of acute asthma in children were retrieved. Ten randomized controlled studies that included a comparison with SVN treatment were selected.

DATA EXTRACTION

Studies were assessed qualitatively by their subject characteristics, design, intervention procedures, outcome measures, and results.

DATA SYNTHESIS

There were marked variations in types of MDI/ADs and in doses administered between and within studies. Major outcome measures included pulmonary function measurements and clinical scores. All studies found MDI/ADs to be effective in the treatment of infants and children with acute asthma. Among those who compared this treatment with SVN, 2 found the MDI/AD superior and the rest found it as effective as the SVN.

CONCLUSIONS

The data support the effectiveness of MDI/ADs as first-line treatment in acute childhood asthma. In view of clinical benefit, safety, lower cost, personnel time, and speed and ease of administration of MDI/ADs compared with SVNs, MDI/ADs should be considered the preferred mode of treatment of children with acute asthma.

Physician-targeted program on inhaled therapy for childhood asthma

BACKGROUND

Inhaled medications are the mainstay of asthma therapy, but significant deficiencies exist in the knowledge and skills of physicians regarding use of metered-dose inhalers (MDI) and spacer devices.

OBJECTIVE

We developed, implemented, and evaluated the effects of a physician-targeted educational program on inhaled therapy in a group of pediatric residents in our institution.

METHODS

Patient-directed instruction sheets on aerosol therapy were developed on the basis of literature review and expert guidelines. These served to establish a consistent foundation for the educational curriculum. The program was delivered through one-on-two teaching sessions (45 minutes). Residents were provided with a summary of theoretical and practical information and with devices for practice (a placebo MDI, InspirEase and AeroChamber holding chambers, and the AeroChamber device with mask). Each session included review of an educational monograph, demonstration of proper technique, and practice with the different devices. The program was evaluated by a randomized-control design. Assessment of practical skills included number of correct steps for the use of MDI (maximum score, 7), InspirEase (maximum, 7) and AeroChamber (maximum, 6). Theoretical knowledge was assessed with 25 multiple-choice questions.

RESULTS

Pretest scores in the experimental group (n = 24) were 3.7 of 7, 1.9 of 7, and 0.3 of 6 steps correct for MDI, InspirEase, and AeroChamber devices, respectively, and 13 of 25 for the theoretical knowledge assessment. The control group (n = 26) had similar pretest scores. After the program the experimental group significantly improved in all parameters: 6.3 of 7, 5.9 of 7, and 4.5 of 6 steps correct for MDI, InspirEase, and AeroChamber devices, respectively, and 18 of 25 questions correct (p < 0.01 for all parameters).

CONCLUSIONS

Implementation of a simple educational program among pediatric residents can significantly increase their skills in the use of inhalational therapy.

What do pediatricians in training know about the correct use of inhalers and spacer devices?

Most patients with asthma in the United States are cared for by nonspecialist physicians. Because inhaled medications are the mainstay of asthma therapy and their successful use requires both practical skills and theoretic knowledge, we wondered how much nonspecialist physicians know about the use of metered-dose inhalers and spacer devices. Fifty pediatricians in training were interviewed individually. Practical knowledge was assessed by asking each to demonstrate correct use of a placebo inhaler and a spacer device (Inspirease [Key Pharmaceuticals, Inc., Miami, Fla.] and Aerochamber with mask [Monaghan Medical Corp., Plattsburgh, N.Y.]). Of the seven recommended steps for use of metered-dose inhalers, the residents demonstrated an average of 3.8 steps correctly. The most common errors included not shaking the metered-dose inhaler before use (18% of residents correct) and insufficient breath holding (28% correct). In testing spacer use, the most common errors included not shaking the canister (16% correct) and incorrect number of activations and inhalations (12% correct). Many residents were not familiar with correct assembly of the spacer (48% correct). Theoretic knowledge of metered-dose inhaler and spacer use was evaluated by a written questionnaire. The most common deficiencies in theoretic knowledge related to the purpose of slow inspiration and breath holding. Most of the participants had been treating children with asthma and had prescribed metered-dose inhalers (45 of 50, 90%) and spacer devices (76%) in the past.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of inspired air conditions on catecholamine response to exercise in asthma

The influence of different inspired air conditions on exercise-induced bronchoconstriction (EIB) is well appreciated. However, the mechanism by which this influence is exerted is uncertain. To determine if varied inspired air conditions during exercise could affect the catecholamine response to physical exercise, we had 13 asthmatic and 6 healthy children (aged 10-18 years) undergo two bouts of cycle ergometry tests under different air conditions. One test was done while breathing cold dry (CD) air (temperature, -20.2 degrees C; relative humidity, 0%) and the other while breathing warm humid (WH) air (temperature, 34.3 degrees C; relative humidity, 100%). Forced expiratory volume in 1 second (FEV1) and plasma catecholamine concentrations were recorded before and after exercise. Marked EIB (48 +/- 5% SEM fall in FEV1 from baseline) developed in all asthmatics after the CD exercise, but no EIB was noted after the WH exercise. Normal controls had no EIB under either test conditions. Plasma levels of catecholamines at rest, and the changes that occurred during and after exercise, were comparable within as well as between the groups in both tests. Catecholamines did not rise in asthmatics following development of EIB. These data demonstrate that inspired air conditions do not influence the sympathoadrenal response to exercise, at least as reflected in plasma catecholamine levels. In fact, this response did not differ between asthmatics and normals, irrespective of the development of EIB. These results are consistent with previous reports about impaired catecholamine response of asthmatics to bronchoconstriction.

Assessment of methacholine-induced airway constriction by ultrafast high-resolution computed tomography

Assessment of changes in airway dimensions during bronchoconstriction is conventionally based on measurements of respiratory mechanics. We evaluated the efficacy of ultrafast high-resolution computed tomography (UHRCT) to directly determine the dynamic changes in cross-sectional area (CSA) of airways in response to methacholine (MCh). UHRCT scans were obtained at functional residual capacity before (baseline) and after intravenous bolus injections of MCh (10(-8.5)-10(-7.0) mol/kg) to seven mechanically ventilated pigs. Changes in CSA of bronchi of varying baseline size (1-10 mm diam) were determined by using a customized image processing software package (VIDA) based on a user-directed computer-adjusted edge-finding algorithm. MCh induced dose-dependent decreases in CSA, which were paralleled by increases in airway opening pressure at higher doses of MCh; at lower doses of MCh, decreases in CSA of smaller airways were detected without concomitant changes in airway opening pressure. Changes in CSA were heterogeneous and variable, especially in the smaller airway ranges. The results of the present study support the concept that UHRCT can be used in conjunction with bolus challenges to effectively determine dose-response changes in airway caliber in both large and small airways. This technique provides data that may not be reflected by conventional lung function measurements and, hence, is a useful tool to study airway reactivity.

Exercise, regardless of induced bronchoconstriction or inspired air conditions, does not alter airway reactivity

The effects of exercise on asthmatic airway caliber are well recognized. Only a few studies, however, evaluated the effects of prior exercise on asthmatic airway reactivity. Eight asthmatic children (ages 10 to 16 years; mean, 12) performed histamine inhalation tests on three occasions assigned in random order: (1) control; (2) 40 to 60 min after exercise (6 min ergometer cycling) done while breathing cold dry (CD) air (temperature = -13 degrees C, relative humidity = 0 percent); and (3) 40 to 60 min after exercise done while breathing warm humid (WH) air (temperature = 33 degrees C, relative humidity = 100 percent). While there was a marked exercise-induced bronchoconstriction (EIB) in the CD test with a postexercise fall in FEV1 of 39.2 +/- 8 percent (mean +/- SEM), there was no EIB in the WH test (4.6 +/- 2 percent). There was no difference, however, in the geometric mean histamine concentration required to produce a 20 percent fall in FEV1 (PC20) among the CD, WH, and control tests (0.52 mg/ml, 0.60 mg/ml, and 0.55 mg/ml, respectively). Airway reactivity in asthmatic children is not influenced by a prior exercise challenge, independent of the conditions of the inspired air during the exercise. Moreover, exercise per se, regardless of development of EIB, does not change the reactivity.

[Spontaneous chylothorax in the neonate]

Chylothorax is a rare cause of respiratory distress in the newborn and is the most frequent type of neonatal pleural effusion. We report 3 cases of spontaneous chylothorax in neonates, 2 boys and 1 girl, all of whom suffered from respiratory distress and required intensive care, including repeated thoracocentesis and mechanical ventilation. Anticipation and prompt recognition of this neonatal emergency and appropriate therapy are essential to ensure its generally favorable prognosis.