Background: The hyperventilation provocation test (HPTest) is a diagnostic tool for idiopathic hyperventilation syndrome (HVS), encountered in some long-COVID patients. However, interpretation of the HPTest remains unclear regarding the relevant P_ETCO₂ values to focus on and whether subjective symptoms should be considered. This study aimed to re-evaluate objective HPTest results for diagnosing HVS by determining accurate P_ETCO₂ kinetics in two groups of patients previously screened via the Nijmegen questionnaire (NQ). Methods: The kinetics of P_ETCO₂ during the HPTest were mathematically modeled and compared between 37 HVS patients (NQ ≥23/64) and 37 healthy controls (NQ <23/64) matched for gender, age, and body dimensions. AUC values with sensitivity and specificity were calculated, and analysis was monitored in a validation cohort of 152 routine HPTests. Results: A threshold value of a less than 12.8 mmHg increment of P_ETCO₂ at the 5th minute of the recovery phase of the HPTest diagnosed HVS patients with excellent sensitivity (0.92) and specificity (0.84). These results were confirmed in the validation cohort, highlighting the presence of 24% false positives/negatives when diagnosing on the basis of complaints in the NQ. Conclusions: For HVS diagnosis, we suggest considering the HPTest, which can more reliably reflect the mechanisms of CO₂ homeostasis and the response of the respiratory center to a stimulus, regardless of the subjective onset of symptoms.

Occupational exposure to charcoal smoke and dust is a threat to workers respiratory system. What is the prevalence of chronic obstructive pulmonary disease (COPD) in charcoal workers as compared to farmers in rural areas of Democratic Republic of Congo (DRC)? This cross-sectional, comparative, and multi-site study was performed in the charcoal-producing provinces of South-Western DRC. We randomly included charcoal workers and compared them to farmers (18 to 70 years old). Air quality indexes, anthropometric, physical activity, sociodemographic characteristics, and related medical events data were recorded. A Lung function questionnaire was used to assess respiratory symptoms (RS) and spirometry was performed. COPD was defined as the presence of RS for more than 3 months with a FEV1/FVC ratio below the lower limit of normal. The prevalence of COPD was calculated, and logistic regression was used to identify COPD-associated factors. We included 485 subjects between August 2020 and July 2021. Charcoal Producers (CP, n = 229) were compared with farmers (n = 118), and charcoal saleswomen (CS, n = 72) were compared to vegetable saleswomen (VS, n = 66). Respective groups were similar in age, job seniority, height, and weight. The air was more polluted at charcoal workplaces. The prevalence of COPD was higher in CP than in farmers (39.7% vs 14.4%; P < 0.0001), and in CS compared to VS (40.3% vs 13.6%; P < 0.0001). Being a charcoal worker was independently associated with COPD in the CP and farmers group: adjusted OR, 3.54 (95% CI, 1.94-6.46), and, in the saleswomen group: 7.85 (95% CI, 2.85-21.5), where it was also independently associated with young age: 0.85 (0.80-0.93) and monthly income: 0.88 (0.83-0.96). In rural areas of DRC, producing or selling charcoal is associated with a higher risk of COPD.

Background: Occupational biomass pollutant exposure as observed in charcoal workers may have significant cardiovascular effects. This study aims to ascertain the prevalence and risk factors of hypertension and high pulse pressure (HPP), a marker of arterial stiffness, in charcoal workers compared with a control group of agricultural workers from the Democratic Republic of Congo. Methods and Results: The charcoal worker and agricultural worker groups (n=485; median age, 35–40 years) were composed of male charcoal producers (n=229), charcoal saleswomen (n=72), male farmers (n=118), and vegetable saleswomen (n=66). We assessed workplace air pollution, sociodemographic parameters, self‐reported physical activity, body composition, exhaled air carbon monoxide, and blood pressure. Hypertension and HPP prevalences were determined. Logistic regression, adjusted for confounding variables was used to identify the risk factors. Charcoal workplaces were more polluted than agricultural workplaces ( P <0.01). Charcoal producers performed higher levels of physical activity ( P =0.018) and demonstrated higher levels of exhaled air carbon monoxide ( P <0.0001) and pulse pressure ( P =0.006), and higher prevalence of grade 1 hypertension ( P =0.007), isolated systolic hypertension ( P =0.04), and HPP ( P =0.02) than farmers. Overall, hypertension (adjusted odds ratio [aOR], 11.76 [95% CI, 6.26–22.13]), level of particulate matter <10 μm pollutants (aOR, 1.001 [95% CI, 1.0002–1.0017]), smoking (aOR, 2.21 [95% CI, 1.15–4.24]) and low education (aOR, 2.14 [95% CI, 1.10–4.17]) were independently associated with HPP. The level of particulate matter <1.0 μm pollutants (aOR, 1.0009 [95% CI, 1.0002–1.0015]), male sex (aOR, 2.09 [95% CI, 1.21–3.64]), and job seniority (aOR, 1.022 [95% CI, 1.004–1.044]) were independently associated with isolated systolic hypertension. Conclusions: Charcoal producers appear to develop isolated systolic hypertension and HPP more, both indices of cardiovascular events in which occupational biomass particles seem to play an early significant role.

Patients with idiopathic hyperventilation syndrome (HVS) displayed preserved central chemosensitivity but altered ventilatory control at rest, characterized by elevated ventilation, increased variability, and a leftward-shifted hypercapnic response. These features were strongly associated with peripheral chemosensitivity, CO ₂ stores, and reduced plant gain, patterns not observed in controls. These findings support a novel integrative model in which altered CO ₂ buffering and peripheral afferent inputs, rather than central mechanisms alone, contribute to ventilatory instability in HVS.

Background: Dynamic hyperinflation (DH) commonly occurs during maximum voluntary ventilation (MVV) in obstructive lung diseases and is usually attributed to expiratory flow limitation. However, in healthy individuals, maximal effort typically remains insufficient to induce DH. This study aimed to determine whether DH can also develop during MVV in normal subjects without expiratory flow limitation, challenging the current concepts of its occurrence in physiological conditions. Methods: Forty-three healthy subjects (25 males/18 females; 40–68 yrs; FEV ₁ : 3.4 ± 0.8 L) performed MVV at increasing breathing frequencies (ranging from 10 to 100 breaths.min ⁻¹ ) and maximal tidal volumes. Inspiratory capacity (IC) was measured at rest and every 12 s during MVV to detect DH. When DH occurred at a certain frequency (BF _DH ), a single additional MVV at a higher frequency was performed to confirm its occurrence. Results: DH occurred at or below 100 breaths.min ⁻¹ in 39 of 43 healthy subjects (91%), with the mean onset at 52 breaths.min ⁻¹ . There was no significant correlation between the frequency of breathing at the onset of DH and age, body mass index, lung volumes, or flows. However, BF _DH was significantly and inversely correlated with resting [IC/FVC], meaning that individuals operating at lower resting ventilatory levels reached DH at lower breath frequency (BF). Conclusion: DH can occur at low and variable breathing frequencies during MVV in healthy subjects. The onset of DH may be related to the mechanical thoracopulmonary state at rest, suggesting that the baseline lung mechanics may determine the susceptibility to DH during high-intensity ventilatory maneuvers.