Infant Pulmonary Function Testing Research Articles

Thoracoabdominal compression and respiratory system compliance in HIV-infected infants.

The thoracoabdominal compression technique (TAC) is used to measure expiratory flow in infants. We investigated whether TAC caused a change in total thoracic compliance (Crs), resistance (Rrs), and respiratory system time constant (Trs). We studied 41 infants (mean age, 12.4 mo; SD, 7.5) from five centers studying longitudinal lung and cardiovascular function of infants from HIV-infected mothers. We measured Crs, Rrs, and Trs before and after TAC. Changes in Crs, Rrs, and Trs after TAC were not dependent on the length of time since TAC. Crs and Trs were reduced after TAC, p = 0.013 and p = 0.003, respectively, whereas Rrs did not change. When compared with uninfected infants, HIV-infected infants had a larger post-pre TAC percent decline in Crs (p = 0.003) and a post-pre TAC rise in mean Rrs (p = 0.03). These differences remained significant after adjusting for sex and age. When performing infant pulmonary function testing, TAC itself produces a temporary decrease in Crs and Trs that is more significant in infants at risk for abnormal lung volume or compliance. Therefore, the sequence of performing the infant lung function parameters should be the same each time the testing is repeated with TAC as the last parameter tested at each testing session.

Measuring pulmonary function in infancy.

In recent years there has been a growing interest in the measurement of pulmonary function in infants for both clinical and research purposes. Such measurements remain limited by the complexity of the equipment as well as by the technical and physiological challenges of testing infants and neonates. Despite these problems, assessment of respiratory function in early life provides exciting information about the post-natal growth and development of lungs in health and disease. The aim of this paper is to discuss the physiological, technical and ethical problems surrounding these procedures, as well as reviewing the current methods of testing pulmonary function in the very young. Consideration is given to the developments needed if infant pulmonary function tests are to realise fully, their potential as research and clinical tools.

Lung transplantation in very young infants

Introduction: Established successes with adult lung transplantation have laid the foundation for extension of this therapeutic modality to infants and children dying of end-stage pulmonary disease. The purpose of this report is to convey our experience with 19 infants undergoing lung transplantation before the age of 6 months. Methods: Six patients with predominantly pulmonary vascular disease and 13 patients with primarily pulmonary parenchymal disease have undergone bilateral sequential lung transplantation at our institution since 1990. Mean age at transplant was 104 ± 44 days, and mean weight was 4.9 ± 1.6 kg. Results: Although early mortality (32%, 6/19) was higher than that previously reported for older pediatric age groups, long-term survival was similar (44% at a maximum follow-up of 6 years). Although anastomotic complications and infections occurred at a rate approximating that seen in older pediatric age groups, episodes of acute rejection appear to occur with decreased frequency. Similarly, at a mean follow-up of 3 years, only 2 (15%) of 13 long-term survivors have evidence of bronchiolitis obliterans. The functional residual capacity, as measured on infant pulmonary function tests, has gradually increased as the children have grown, suggesting that lung growth is occurring. Conclusions: Bilateral lung transplantation is a viable alternative in infants dying of end-stage pulmonary disease. Efforts directed toward avoiding the complications that lead to early posttransplant mortality combined with the seemingly lower incidence of early and late rejection may provide long-term results better than those in other age groups. (J Thorac Cardiovasc Surg 1999;118:796-804)

Comparison of Lung Function in Infants Exposed to Maternal Smoking and in Infants With a Family History of Asthma

To compare lung function in infants exposed to maternal smoking with lung function in infants with a family history of asthma. There are no published studies comparing lung function in both groups. Cross-sectional study. A tertiary pulmonary care center at a children's hospital. One hundred five infants with daily wheezing. Thirty-five infants had persistent exposure to maternal smoking, and 70 had a family history of asthma in parents or siblings. Infant pulmonary function tests were compared between the two groups. The ratio of terminal to peak expiratory flow at tidal breathing at 25% of the previous expiration remaining and the ratio of terminal to peak expiratory flow with forced expiration at 25% of the previous expiration remaining (FEF25/PFEF) were used to evaluate peripheral airflow. A > 25% improvement in FEF25/PFEF after a bronchodilator challenge test was considered a positive response. Most infants in both groups had evidence of peripheral airflow obstruction with forced expiration. In infants exposed to maternal smoking, only 4 of 35 (11.4%) responded to a bronchodilator, compared to 51 of 70 (72.9%) in the group with a family history of asthma (p < 0.0005). There was no statistically significant difference in total respiratory system compliance, total respiratory system resistance, tidal volume, and degree of peripheral airflow obstruction at tidal breathing or after forced expiration in both groups. Infants with exposure to maternal smoking and infants with a family history of asthma have altered lung function, and a positive response to a bronchodilator is one variable that seems to differentiate the two groups.

Lung function in infants with wheezing and gastroesophageal reflux.

Eighty-four otherwise healthy infants with daily wheezing underwent infant pulmonary function tests (IPFTs) and 24-h esophageal pH probe studies. Fifty-four (64%) infants had positive pH probe studies, and 30 infants had negative pH probe studies. Many infants in both groups had evidence of peripheral airflow obstruction at tidal breathing and on forced expiration as measured by thoracoabdominal compression. In infants with gastroesophageal reflux (GER), only 9 of 54 (16.6%) responded to bronchodilator therapy compared to 20 of 30 (66.6%) in the group with negative pH probe studies (P < 0.0005). In infants with positive pH studies, family history of asthma (n = 16) correlated well with positive response to bronchodilators (P < 0.0005), and all infants exposed to maternal smoking (n = 11) had no response to bronchodilators. Forty-four percent of infants with a positive pH probe had no gastrointestinal symptoms suggestive of GER. In infants with a negative pH probe, family history of asthma (n = 24) correlated well with positive response to bronchodilators (P < 0.0005), and exposure to maternal smoking (n = 8) correlated well with no response to bronchodilator therapy (P < 0.0005). We conclude that silent GER is common in infants with persistent wheezing. Furthermore, infants with GER are less likely to respond to bronchodilator therapy, and exposure to maternal smoking and family history of asthma may be significant independent factors.

Lung function in infants with wheezing and gastroesophageal reflux

Eighty-four otherwise healthy infants with daily wheezing underwent infant pulmonary function tests (IPFTs) and 24-h esophageal pH probe studies. Fifty-four (64%) infants had positive pH probe studies, and 30 infants had negative pH probe studies. Many infants in both groups had evidence of peripheral airflow obstruction at tidal breathing and on forced expiration as measured by thoracoabdominal compression. In infants with gastroesophageal reflux (GER), only 9 of 54 (16.6%) responded to bronchodilator therapy compared to 20 of 30 (66.6%) in the group with negative pH probe studies (P < 0.0005). In infants with positive pH studies, family history of asthma (n = 16) correlated well with positive response to bronchodilators (P < 0.0005), and all infants exposed to maternal smoking (n = 11) had no response to bronchodilators. Forty-four percent of infants with a positive pH probe had no gastrointestinal symptoms suggestive of GER. In infants with a negative pH probe, family history of asthma (n = 24) correlated well with positive response to bronchodilators (P < 0.0005), and exposure to maternal smoking (n = 8) correlated well with no response to bronchodilator therapy (P < 0.0005). We conclude that silent GER is common in infants with persistent wheezing. Furthermore, infants with GER are less likely to respond to bronchodilator therapy, and exposure to maternal smoking and family history of asthma may be significant independent factors. Pediatr Pulmonol. 1999; 27:236–241. © 1999 Wiley-Liss, Inc.

Lung function testing in infants

During recent years, there has been rapid development in the availability and application of pulmonary function tests in infants and young children. Whereas original methods were based on adaptations of classical techniques, over the past decade there has been an increasing trend towards developing less complex techniques specifically for use in infants and young children. Interpretation of these measurements requires a knowledge of respiratory physiology, and may be confounded by an unstable end expiratory level, compliant chest wall, dominance of the upper airways, difficulty in achieving flow limitation in healthy infants, and the variability of respiratory, lung or airway resistance which increases the difficulty of assessing the significance of changes in resistance as a result of treatment or challenge. Nevertheless, with care, the assessment of respiratory function during infancy and early childhood can increase knowledge of the growth and development of the respiratory system, and our understanding of the patho-physiological processes underlying respiratory diseases in early life. They also have the potential to provide valuable objective outcome measures in the quest for effective preventive and therapeutic strategies in respiratory medicine.

Parental attitudes toward infant pulmonary function testing.

Infant pulmonary function tests (PFTs) have proven increasingly popular and useful for clinical and research purposes. Informed consent requires accurate information on side effects. Our aim was to quantify minor side effects from a parental point of view by means of a questionnaire. The parents of 97 infants attending for PFTs were asked to complete a simple questionnaire. Eighty-one parents (84%) returned the questionnaire. Forty-one percent felt that their infants were not troubled by the process of administering the sedative chloral hydrate, whereas 55% suffered mild to moderate distress. In contrast, 94% of infants were not distressed by the actual PFTs. Similarly, 46% of parents were not distressed by the administration of sedative to their infant, with 49% expressing distress to a mild or moderate degree. Although 73% of parents were not distressed by watching their infants undergo the PFTs, 27% were to a mild to moderate degree. Seventy-three percent of infants were untroubled on waking. Seventy percent of infants had a good nights sleep after the PFTs. The vast majority of parents (94%) were happy to recommend that others allow their infants to undergo similar testing. We noted that most problems caused by infant PFTs relate to the administration of the sedative. Most infants awake from the tests not distressed and sleep normally the following night.

The Use of Omeprazole in Infants with Gastroesophageal Reflux-induced Wheezing

We evaluated the use of proton pump inhibitor omeprazole to control severe gastroesophageal reflux (GER) in two otherwise healthy infants (ages 4 and 7 months) presenting with respiratory symptoms only. Omeprazole was given when standard antireflux therapy (H2 receptor antagonists [H2RA] and prokinetic agents) for at least 6 weeks failed to improve the wheezing, and prolonged pH probe and infant pulmonary function tests failed to show any significant improvement. Within 6 weeks of omeprazole therapy the cough and wheezing had completely resolved. In otherwise healthy infants with refractory GER-induced wheezing, omeprazole therapy may avoid the need for fundoplication in some children and may be considered prior to any antireflux surgery. Prospective long-term studies in infants and children are warranted to establish safety for long-term use.

291 RESPIRATORY MECHANICHS IN INFANTS WITH ACUTE BRONCHIOLITIS

Objective: to determine alterations in pulmonary function tests in infants in acute phase of bronchiolitis. Subjects and methods: Partial forced expiratory flow-volume curves obtained by an inflatable jacket and end-inspiratory single occlusion test were used to determine maximal flow at Functional Residual Capacity (VmaxFRC) and total respiratory system compliance and resistance (Crs, Rrs) in 54 previously healthy infants in acute phase of bronchiolitis and in 44 healthy control infants aged 1-12 months. PEDS and PUFF systems (Medical Associates, Hatfield, Pa, USA) were used for these measurements. Results: see table. Table: age (yr); Length (cm); VmaxFRC (mL/s). (mL/cmH2O). Rrs (cmH2O/Ls). % Predicted by Tepper et al. Am Rev Respir Dis 1986;134:513-9. Mean (standard deviation). Comparision by t test for independent samples. NS: no significative. Conclusion: Important decrease in VmaxRFC and compliance with no significant increase in resistance characterizes acute phase of bronchiolitis.

Infant pulmonary function testing workshop Anaheim, California, May 11, 1991

Infant pulmonary function testing workshop Anaheim, California, May 11, 1991

Infant Pulmonary Function Testing Workshop II London, England, September 12, 1990

Infant Pulmonary Function Testing Workshop II London, England, September 12, 1990

Pulmonary function testing in infants with respiratory syncytial virus bronchiolitis requiring mechanical ventilation

Pulmonary function testing in infants with respiratory syncytial virus bronchiolitis requiring mechanical ventilation

Pulmonary function testing in infants with respiratory syncytial virus bronchiolitis requiring mechanical ventilation

Pulmonary function testing in infants with respiratory syncytial virus bronchiolitis requiring mechanical ventilation

Pulmonary Function Testing in Infants and Neonates

Pulmonary Function Testing in Infants and Neonates

Effect of forced expiration on thoracic gas volume in wheezy infants

Partial expiratory flow-volume curves are commonly used in infant pulmonary function testing. The flow measurements are volume dependent and thoracic gas volume (TGV) is often measured in conjunction with forced expiratory maneuvers. Since it is not possible to make continuous, simultaneous measurements of TGV during forced expiration, it is assumed that lung volume returns to its original value after forced expiration. To test this assumption we measured TGV using a whole body plethysmograph in 14 wheezy infants before and after a series of forced expirations produced with an inflatable jacket. Forced expiration did not cause a significant change in group mean TGV measurements. Examination of individual data did not show any systematic difference between TGV measured before and after forced expiration. These results suggest that repeated forced expirations do not alter TGV within the time scale of usual pulmonary function testing protocols.

Neck and Body Position Effects on Pulmonary Mechanics in Infants

Pulmonary mechanics and ventilatory parameters were measured in 30 former preterm infants at a postterm age of 8 to 10 months. All subjects had required assisted ventilation in the neonatal period and 16 had a history of bronchopulmonary dysplasia. Each infant was studied in both supine and semisitting positions, and in each body position the infants were studied with neutral, flexed, and extended neck positions. Baseline measurements (body supine, neck neutral) and the response to postural changes did not differ between infants who had had bronchopulmonary dysplasia and those who had not. Change in body position from supine to semisitting decreased total pulmonary resistance (P less than .05) and increased specific lung compliance (P less than .01). Neck flexion increased resistance (P less than .001) in both body positions but did not influence compliance. These postural effects are consistent with an increase in functional residual capacity in the semisitting position and a decrease in pharyngeal area during neck flexion. Thus, posture needs to be precisely controlled during pulmonary function testing in infants. Furthermore, optimal neck and body position may improve their clinical status.

Short-term variability of pulmonary function tests in infants with bronchopulmonary dysplasia.

We determined the short-term variability of pulmonary function in infants recovering from bronchopulmonary dysplasia. Sixteen infants with birth weight of 1,231 +/- 929 grams (mean +/- SD) and gestational age of 29 +/- 4 weeks were studied twice at 17 +/- 8 weeks postnatally at intervals of 4 to 8 days during a period of clinical stability. The infants were still on supplemental oxygen but were off diuretics and bronchodilators. We used a modification of the rapid thoracic compression method to measure forced expiratory flow (Vmax FRC) and the time constant (tau) of expiratory flow at functional residual capacity. Thoracic gas volume (TGV), mean and total airway resistance (RawM and RawT), and mean and total specific airway conductance (SGawM and SGawT) were measured in a whole body pressure plethysmograph. An esophageal balloon was used to measure dynamic pulmonary compliance (Cdyn). Variabilities were defined as the standard deviation of percent changes between the first and second tests. They were 30% for VmaxFRC, 23% for tau, 12% for TGV, 20% for RawM, 35% for RawT, 25% for SGawM, 72% for SGawT, and 23% for Cdyn. All these tests are useful in assessing pulmonary function of infants with BPD; however, their variability must be taken into account when interpreting short-term changes.

On the accuracy of pulmonary function testing in infants (see pp. 145–151 and pp. 152‐157)

On the accuracy of pulmonary function testing in infants (see pp. 145–151 and pp. 152‐157)

Inherent variability of pulmonary function tests in infants with bronchiolitis.

During the last decade, many new methods of assessing pulmonary function in infants have been introduced. However, considerable controversy has arisen when these different techniques are used to assess the efficacy of various inhaled medications. The currently employed measures of pulmonary function have been reported to have coefficients of variation of less than 10%. However, these figures refer to repeated measurements made in individual babies over a short period of time, with the infant in a constant position. They may not be applicable to studies on the effects of drugs when a significant time interval elapses between measurements, particularly if the infant is repositioned during this time. In the present study, we found that the variability of measurements of thoracic gas volume (TGV), passive respiratory mechanics, and forced expiration approximately doubled if the infant was taken out of the plethysmograph, or repositioned within the plethysmograph, between sets of measurements. The between-test coefficients of variation ranged from 4.8% to 18.9% for TGV, 7.8% to 23.5% for respiratory system resistance, from 5.0% to 24.1% for respiratory system compliance, and from 10.8% to 36.1% for maximal flow at functional residual capacity. These results demonstrate that the commonly employed infant pulmonary function tests have wide variability in infants with acute wheezing illnesses. Before studying the efficacy of therapeutic interventions in such infants, it is necessary to establish the individual variability of the tests in the infants under the conditions of the study. Failure to do so may result in erroneous conclusions and recommendations.