A decrease in plant gain, namely CO2 stores, characterizes dysfunctional breathing whatever its subtype in children

Question

1. What is the primary objective of the retrospective study on children with DB?

2. What criteria were used to select children for the study?

3. What is the Borg scale used for in CPETs?

4. What parameters are obtained from HVPT recordings?

Accepted Answer

The primary objective of the retrospective study on children with DB is to assess whether or not children suffering from different subtypes of DB exhibit decreased plant gain. The hypothesis is that all children with DB, whether or not hypocapnia was evidenced during a CPET, may exhibit similar kinetics of PETCO 2 decrease during the HVPT and similar levels of plant gain measured during tidal ventilation. This study aims to understand the relationship between plant gain and DB in children.

Accepted Answer

The criteria used to select children for the study included: 1) children with physiological dyspnea on exercise, 2) children with DB and alveolar hyperventilation on exercise, 3) children with DB with hyperventilation on exercise without hypocapnia, and 4) children with DB without hyperventilation on exercise. The selection process involved normal lung function, normal echocardiography, and specific VE'/V'CO2 slope values during CPET. Children were also categorized based on their Nijmegen score and PaCO2 levels. The study excluded children with overt current disease, respiratory or cardiopulmonary, based on normal or near-normal CPET results, lung function, chest radiography, and echocardiography. Similar numbers of children were selected for both the Phys/alvHV groups and the nonalvHV/Dysp groups, with non-significant differences for age and sex.

Accepted Answer

The Borg scale is used to score breathlessness at different stages of the CPET. Subjects rate their breathlessness at baseline, 30% and 40% of maximal ventilation, and at peak exercise. This subjective measure helps assess the individual's perception of their breathlessness during the test, providing valuable insights into their cardiopulmonary function and exercise tolerance. The Borg scale ranges from 6 (no exertion) to 20 (maximal exertion), allowing for a standardized assessment of breathlessness across different individuals and conditions. By incorporating the Borg scale into CPETs, researchers can better understand the relationship between physiological parameters and subjective experiences, leading to more comprehensive and accurate evaluations of cardiopulmonary health.

Accepted Answer

From HVPT recordings, mean and maximum values of FETCO 2 during resting breathing, minimum value of voluntary hyperventilation, and kinetics of FETCO 2 decrease during hyperventilation and increase during recovery are obtained. These parameters are used to fit linear, exponential, and logarithmic models to analyze the data.

Accepted Answer

Three distinct frequency bands were considered: low-frequency oscillations with periods of 16-50 breaths/cycle, medium-frequency oscillations of 5-15 breaths/cycle, and high-frequency oscillations of 2-4 breaths/cycle. These bands were used to analyze loop gain and plant and controller gains in tidal breathing measurements. The choice of these frequency bands was based on the expectation of cyclical modifications of ventilation in DB, as mentioned in Bokov et al., 2016. Additionally, a decrease in plant gain could lead to decreased loop gain over specific frequencies, justifying the use of these frequency bands for loop gain analysis. The study utilized a constrained bivariate model, as described in Bokov et al., 2018, to fit the changes from the baseline levels of ventilatory parameters obtained from tidal breathing measurements.

Accepted Answer

In the study, the Kruskal-Wallis test was used for continuous variables, Mann-Whitney test for subgroup comparisons, chi-squared test for categorical variables, and Pearson test for linear correlations. A p-value of less than 0.05 was considered significant. No correction for multiple testing was done due to the pathophysiological design of the study (Rothman, 1990). Statistical analyses were performed using StatView 5.0 software.

Accepted Answer

The clinical and CPET characteristics of the four groups of children with different breathlessness subtypes are described in Table 1. The Phys group had no resting dyspnea, while 37 out of 42 children with DB had resting dyspnea. The Phys group had lower STAI-C scores and lower dyspnea on exercise at 40% of the predicted maximal minute ventilation compared to the other groups. Plant gain and loop gain at high frequencies were significantly different among the groups, with the Phys group showing higher values. The slope of linear decrease in FETCO 2 during hyperventilation was more negative in the Phys group, and the intercept was higher. The kinetics of FETCO 2 decay and subsequent recovery were also different among the groups, with the Phys group showing a better fit with exponential and logarithmic functions. These findings suggest distinct physiological and clinical characteristics among the different breathlessness subtypes in children.

A decrease in plant gain, namely CO2 stores, characterizes dysfunctional breathing whatever its subtype in children

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Most frequently asked questions

1. What is the primary objective of the retrospective study on children with DB?

2. What criteria were used to select children for the study?

3. What is the Borg scale used for in CPETs?

4. What parameters are obtained from HVPT recordings?

5. What frequency bands were considered for tidal breathing measurements?

6. What statistical tests were used in the study?

7. What are the differences in clinical and CPET characteristics among the four groups of children with different breathlessness subtypes?

Citations

Dyspnea in young subjects with congenital central hypoventilation syndrome

References

No adjustments are needed for multiple comparisons.

Efficacy of nijmegen questionnaire in recognition of the hyperventilation syndrome

Non‐pharmacological interventions for somatoform disorders and medically‐unexplained physical symptoms (MUPS) in adults

Dysfunctional breathing: a review of the literature and proposal for classification

The Nijmegen Questionnaire and dysfunctional breathing

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