Variability of the raised volume rapid thoracic compression technique in infants with recurrent wheezing

Common cold decreases lung function in infants with recurrent wheezing

Background

Common acute viral respiratory infections (colds) are the most frequent cause of exacerbations in infants with recurrent wheezing (RW). However, there is no quantitative information about the effect of colds on the lung function of infants with RW. This study was undertaken to determine the effect of common cold on forced expiratory parameters measured from raised lung volume in infants with RW.

Methods

Spirometric lung function (expiratory flows from raised lung volume) was randomly assessed in 28 infants with RW while they had a common cold and when asymptomatic.

Results

It was found that during colds there was a significant decrease in all forced expiratory parameters and this was much more evident for flows (FEF_50%, FEF_75% and FEF_25–75%) which were definitively abnormal (less than −1.65 z-score) in the majority of infants. There was not association between family asthma, tobacco exposure, and other factors, with the extent of lung function decrease during colds. Tobacco during pregnancy but not a history of family asthma was significantly associated to lower expiratory flows; however, the association was significant only when infants were asymptomatic.

Conclusion

This study shows that common colds cause a marked reduction of lung function in infants with RW.

Effect of inhaled fluticasone on lung function in infants with recurrent wheezing: a randomised controlled trial

BACKGROUND

Inhaled corticosteroids are used to treat infants with troublesome asthma-like symptoms but their effect on the lung function of these young patients is controversial.

MATERIAL AND METHODS

Forty-four infants with recurrent wheezing (more than 3 episodes) and family history of asthma completed this randomised, parallel, double-blind, controlled trial to compare the effect on lung function (main endpoint) of once-daily inhaled fluticasone (375 microg) versus placebo for 3 months. Pulmonary function was measured while infants were asymptomatic, using the raised volume rapid thoracic compression technique (spirometry-like), and values were converted to z-scores.

RESULTS

The fluticasone group showed a significant increase in forced flows, (p < 0.001), a lower number of physician diagnosed wheezing episodes (p < 0.002), and a significant decrease in the parent-reported number of wheezing episodes per month (p < 0.03), as compared to placebo. One third of parents in the placebo group reported a clinical improvement in their infants. There was no significant difference in morning plasma cortisol between groups at entry or discharge.

CONCLUSIONS

We conclude that once-daily treatment with 375 microg fluticasone increased forced flows and controlled symptoms in infants with recurrent wheezing without altering plasma cortisol levels. The spirometry-like technique is a useful tool to objectively assess the efficacy of anti-asthma medications in infants with repeated troublesome asthma-like symptoms.

Influence of sighs in the raised volume rapid thoracic compression technique (RVRTC) in infants

The raised volume rapid thoracic compression (RVRTC) technique has shown to be very promising in the evaluation of infant's lung function. In this technique lungs are inflated several times to a preset pressure prior to the thoracic compression. Many infants made a spontaneous inspiration (sigh) at the end of these inflations. Our hypothesis was that such sighs could change the major variables derived by this technique and the objective of this study was to evaluate the influence of these sighs during lung inflation in the RVRTC technique in infants. Pairs of maneuvers with and without sighs during lung inflation were obtained in 33 of 48 consecutive tests. Curves with sighs showed significantly higher values of FVC (median: 456 x 437 ml; P < 0.001) and FEV0.5 compared to those without, whereas FEF75 and FEF85 were significantly lower (median: 417 x 439 ml/sec, P = 0.008 and 251 x 273 ml/sec, P = 0.01; respectively). The mean percent change between maneuvers for FVC, FEV0.5, FEF75, and FEF85 was respectively: 6.4%, 3.8%, -3.1%, and -3.5%. These differences represent a mean change of 0.38 z score for FVC and of 0.12 z score for FEF75 and FEF85. In conclusion, the presence of sighs during lung inflation significantly changes RVRTC values in infants. We suggest that the presence or the absence of sighs should be registered for each maneuver and that it should be considered for within and between subject comparisons.

[Advances in the study of infant lung function: forced expiratory maneuvers from an increased lung volume]

Forced expiratory maneuvers from an increased lung volume in infants date from 1989 and consist of raising the inspiratory volume by applying a specific inflation pressure until a level close to the total lung capacity is reached. The chest and abdomen are then compressed by means of an inflatable jacket in order to obtain a forced expiratory flow-volume curve similar to that obtained for an adult. Forced expiration from an increased lung volume in infants is useful, just as the maneuver is in older patients, for studying airway function, diagnosing obstructive diseases early, and assessing response to treatment. The objective of this review is to provide information on the physiological bases and technical aspects of a lung function test that has proven highly useful for the study of the airways of healthy infants as well as those with respiratory diseases.