PFTs in Infants and Pre - School Children

Introduction

Evaluating lung functions is a particularly challenging task in this age group. This assumes more importance since recurrent cough & wheezing is so common in this age group. Apart from this, it is very important to assess and regularly monitor cases of chronic neonatal lung diseases and cystic fibrosis. Challenges faced in executing the tests: PFTs in infants are conducted under sedation. However, in the pre school age group, they are too old to sedate and sedation would interfere with the results. They have a short attention span and compliance is an important issue.

Test

Following tests are accepted as per guidelines.

1. Standard spirometry:

   Recent literature gives enough evidence that this test is possible in pre school children with appropriate and standardized modification of the acceptability and reproducibility criteria.

2. Forced oscillation (FOT)

   This is a simple, technique requiring minimal participation from the child and is performed during tidal breathing. External pressure oscillations are applied at the mouth and flow & pressure changes are calculated to obtain impedance, resistance and reactance of the respiratory system. This technique has been used to diagnose airway obstruction and to evaluate response to bronchodilators in asthma. Responses to treatment for exacerbations in cases of cystic fibrosis have also been possible with the help of reactance values.

3. Interrupter resistance (Rint)

   In this test a shutter device is used to interrupt airflow during normal, tidal breathing to measure resistance. Usually measurements are done at the end of expiration although they are possible during both inspiration and expiration. This test has been used to differentiate cases of cystic fibrosis and asthma from normal children and also in children exposed to passive smoking.

4. Specific airway resistance measured in a Plethysmograph

   Details of the technique and procedure have been already discussed.

5. Multiple Breath Inert Gas washout technique

   This test evaluates the non – homogeneity of ventilation and is especially of use in evaluating children with peripheral airway obstruction.