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Thoracoabdominal compression and respiratory system compliance in HIV-infected infants
A C Platzker1, A A Colin, X C Chen
1The Divisions of Pediatric Pulmonology, Childrens Hospital Los Angeles, CA, USA. aplatzker@chla.usc.edu
Insights
The thoracoabdominal compression technique (TAC) temporarily reduces total thoracic compliance and the respiratory system time constant in infants. This effect is more pronounced in HIV-infected infants, suggesting careful parameter sequencing during pulmonary function testing.
Area of Science:
- Pediatric Pulmonology
- Infant Respiratory Physiology
Background:
- The thoracoabdominal compression technique (TAC) is a standard method for measuring expiratory flow in infants.
- Understanding the impact of TAC on respiratory mechanics is crucial for accurate pulmonary function testing in infants.
Purpose of the Study:
- To investigate the effects of TAC on total thoracic compliance (Crs), resistance (Rrs), and respiratory system time constant (Trs) in infants.
- To compare these effects between HIV-infected and uninfected infants.
Main Methods:
- 41 infants (mean age 12.4 months) from longitudinal studies of infants born to HIV-infected mothers were assessed.
- Respiratory parameters (Crs, Rrs, Trs) were measured before and after the application of TAC.
- Statistical analyses were performed to determine the significance of changes and differences between groups.
Main Results:
- TAC significantly reduced Crs (p=0.013) and Trs (p=0.003), with no significant change in Rrs.
- HIV-infected infants showed a greater percentage decline in Crs and a rise in Rrs post-TAC compared to uninfected infants.
- These differences persisted after adjusting for sex and age.
Conclusions:
- TAC induces transient decreases in Crs and Trs, more pronounced in infants potentially at risk for abnormal lung function.
- The findings underscore the importance of consistent testing protocols, recommending TAC as the final measurement in infant pulmonary function tests.
Abstract:
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.