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

Background: Whether dysfunctional breathing (DB) subtype classification is useful remains undetermined. The hyperventilation provocation test (HVPT) is used to diagnose DB. This test begins with a 3-min phase of hyperventilation during which fractional end-tidal CO2 (FETCO2) decreases that could be an assessment of plant gain, which relies on CO2 stores. Our aim was to assess 1) whether the children suffering from different subtypes of DB exhibit decreased plant gain and 2) the relationships between HVPT characteristics and plant gain. Methods: We retrospectively selected 48 children (median age 13.5 years, 36 females, 12 males) who exhibited during a cardiopulmonary exercise test either alveolar hyperventilation (transcutaneous PCO2 < 30 mmHg, n = 6) or inappropriate hyperventilation (increased VE'/V'CO2 slope) without hypocapnia (n = 18) or dyspnea without hyperventilation (n = 18) compared to children exhibiting physiological breathlessness (dyspnea for sports only, n = 6). These children underwent tidal-breathing recording (ventilation and FETCO2 allowing the calculation of plant gain) and a HVPT. Results: The plant gain was significantly higher in the physiological group as compared to the dyspnea without hyperventilation group, p = 0.024 and hyperventilation without hypocapnia group, p = 0.008 (trend for the hyperventilation with hypocapnia group, p = 0.078). The slope of linear decrease in FETCO2 during hyperventilation was significantly more negative in physiological breathlessness group as compared to hyperventilation without hypocapnia group (p = 0.005) and dyspnea without hyperventilation group (p = 0.049). Conclusion: The children with DB, regardless of their subtype, deplete their CO2 stores (decreased plant gain), which may be due to intermittent alveolar hyperventilation, suggesting the futility of our subtype classification.

Diagnostic tests and subtypes of dysfunctional breathing in children with unexplained exertional dyspnea.

BACKGROUND: Inappropriate hyperventilation during exercise may be a specific subtype of dysfunctional breathing (DB). OBJECTIVE: To assess whether Nijmegen questionnaire and hyperventilation provocation test (HVPT) are able to differentiate inappropriate hyperventilation from other DB subtypes in children with unexplained exertional dyspnea, and normal spirometry and echocardiography. METHODS: The results were compared between a subgroup of 25 children with inappropriate hyperventilation (increased V'E/V'CO2 slope during a cardiopulmonary exercise test (CPET)) and an age and sex matched subgroup of 25 children with DB without hyperventilation (median age, 13.5 years; 36 girls). Anxiety was evaluated using State-Trait Anxiety Inventory for Children questionnaire. RESULTS: All children were normocapnic (at rest and peak exercise) and the children with hyperventilation had lower tidal volume/vital capacity on peak exercise (shallow breathing). The Nijmegen score correlated positively with dyspnea during the CPET and the HVPT (p = 0.001 and 0.010, respectively) and with anxiety score (p = 0.022). The proportion of children with a positive Nijmegen score (≥19) did not differ between hyperventilation (13/25) and no hyperventilation (14/25) groups (p = 0.777). Fractional end-tidal CO2 (FETCO2 ) at 5-min recovery of the HVPT was < 90% baseline in all children (25/25) of both subgroups. Likewise, there was no significant difference between the two subgroups for other indices of HVPT (FETCO2 at 3-min recovery and symptoms during the test). CONCLUSION: The validity of the Nijmegen questionnaire and the HVPT to discriminate specific subtypes of dysfunctional breathing, as well as the relevance of the inappropriate hyperventilation subtype itself may both be questioned.

Carbon dioxide levels during polygraphy in children with sleep-disordered breathing.

PURPOSE: The recent scoring rules of the American Academy of Sleep Medicine (AASM) define hypoventilation in children as a carbon dioxide (CO2) level of >50 mmHg for >25 % of total sleep time (partial pressure of CO2 (PCO2) > 50[>25 %]). As there is no validated level of nocturnal hypoventilation with regard to end-organ damage in children, we evaluated the prevalence of hypoventilation with the AASM definition but also with a lesser degree of elevated CO2 in children with sleep-disordered breathing (SDB). METHODS: Transcutaneous CO2 (PtcCO2) was recorded during overnight polygraphy (PG). Hypoventilation was defined according to four definitions: the AASM score (PCO2 > 50[>25 %]), the peak value of PtcCO2 > 50 mmHg (PtcCO2 > 50[peak]), a percentage of PtcCO2 > 50 mmHg > 2 % of nighttime recording (PtcCO2 > 50[>2 %]) or a nocturnal PtcCO2 > 10 mmHg above waking baseline level (PtcCO2[>10 mmHg]). PtcCO2 indices were correlated to the apnoea-hypopnoea index (AHI) and oxygenation indices. RESULTS: PGs from 221 children with suspicion of obstructive sleep apnoea (72 %), neuromuscular diseases (21 %), and lung diseases (7 %) were analysed. The prevalence of hypoventilation according to PCO2 > 50[>25 %], PtcCO2 > 50[peak], PtcCO2 > 50[>2 %] and PtcCO2[>10 mmHg] were 16, 27, 31 and 52 %, respectively, and did not differ between the three diagnostic groups. Significant but weak correlations were observed between hypoventilation and AHI and oxygenation indices. CONCLUSIONS: Nocturnal hypoventilation occurs in a large number of children referred for SDB, independent of the underlying disease, when more stringent criteria than those of the AASM are used. The poor correlation between hypoventilation and AHI or oxygenation indices is in favour of CO2 being a supplemental index of SDB.

Pulmonary sarcoid-like granulomatous disease in an 11-month-old girl.

Sarcoidosis is a chronic granulomatous disease of unknown aetiology. It is extremely rare in children, especially the early onset form, presenting with eye, skin and joint symptoms but no lung involvement. We report an 11-month-old girl with granulomatous disease restricted to the lungs consistent with sarcoidosis. This unusual presentation has never been described in the paediatric literature so far.