scholarly journals EXPRESS: PeakPETCO2 combined with FEV1/FVC predicts vasodilator-responsive patients with idiopathic pulmonary arterial hypertension

2021 ◽  
pp. 204589402110597
Author(s):  
cijun Luo ◽  
Hong-Ling Qiu ◽  
Chang-wei Wu ◽  
Jing He ◽  
Ping Yuan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Function ◽  
Partial Pressure ◽  
Minute Ventilation ◽  
Cardiopulmonary Exercise Testing ◽  
Prediction Rule ◽  
Pulmonary Artery Hypertension ◽  
Heart Catheterization ◽  
Hemodynamic Effects ◽  
End Tidal

Background: Cardiopulmonary exercise testing (CPET) and pulmonary function test (PFT) are important methods for detecting human cardio-pulmonary function. Whether they could screen vasoresponsiveness in idiopathic pulmonary artery hypertension (IPAH) patients remains undefined. Methods: One hundred thirty-two IPAH patients with complete data were retrospectively enrolled. Patients were classified as vasodilator-responsive (VR) group and vasodilator-nonresponsive (VNR) group on the basis of the acute vasodilator test. PFT and CPET were assessed subsequently and all patients were confirmed by right heart catheterization. We analyzed CPET and PFT data and derived a prediction rule to screen vasodilator-responsive patients in IPAH. Results: Nineteen of VR-IPAH and 113 of VNR-IPAH patients were retrospectively enrolled. Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects (lower RAP, m PAP, PAWP and PVR). And VR-IPAH patients had higher anaerobic threshold (AT), peak partial pressure of end-tidal carbon dioxide (PETCO2), oxygen uptake efficiency (OUEP) and FEV1/FVC (P all < 0.05), while lower peak partial pressure of end-tidal oxygen (PETO2) and minute ventilation (VE)/carbon dioxide output (VCO2) slope (P all < 0.05). FEV1/FVC (Odds Ratio [OR]: 1.14, 95% confidence interval [CI]: 1.02-1.26, P = 0.02) and PeakPETCO2 (OR: 1.13, 95% CI: 1.01-1.26, P = 0.04) were independent predictors of VR adjusted for age, sex and body mass index. A novel formula (= -16.17 + 0.123 × PeakPETCO2 + 0.127×FEV1/FVC) reached a high area under the curve value of 0.8 (P = 0.003). Combined with these parameters, the optimal cutoff value of this model for detection of VR is -1.06, with a specificity of 91% and sensitivity of 67%. Conclusions: Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects. Higher FEV1/FVC and higher peak PETCO2 were associated with increased odds for vasoresponsiveness. A novel score combining Peak PETCO2 and FEV1/FVC provides high specificity to predict VR patients among IPAH.

scholarly journals Ventilatory parameters measured during a physiological study of simulated powered air-purifying respirator failure in healthy volunteers

2021 ◽  
pp. 0310057X2097898
Author(s):  
Lachlan F Miles ◽  
Timothy Makar ◽  
Chad W Oughton ◽  
Philip J Peyton
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Healthy Volunteers ◽  
Minute Ventilation ◽  
Peripheral Oxygen Saturation ◽  
Thermal Discomfort ◽  
Fraction Of Inspired Oxygen ◽  
Mechanical Devices ◽  
End Tidal ◽  
High Level

Powered air-purifying respirators (PAPR) are a high level of respiratory personal protective equipment. Like all mechanical devices, they are vulnerable to failure. The precise physiological consequences of failure in live subjects have not previously been reported. We conducted an observational safety study simulating PAPR failure in a group of nine healthy volunteers, wearing loose-fitting hoods, who were observed for a period of ten minutes, or until they requested the experiment be aborted, with continuous monitoring of gas exchange. Relative to baseline, participants demonstrated median reductions in peripheral oxygen saturation of 3.5% (95% confidence interval (CI) –4% to –2%; P = 0.0039) and fraction of inspired oxygen of 0.045 (95% CI –0.05 to –0.04; P = 0.0039), and median increases in inspired partial pressure of carbon dioxide of 27 mmHg (95% CI 23.5–32 mmHg; P = 0.0039), end-tidal partial pressure of carbon dioxide of 11 mmHg (95% CI 7–16 mmHg; P = 0.0039) and minute ventilation of 30 l/min (95% CI 19.4–35.9 l/min; P = 0.0039). Median collateral entrainment of room air into the hood was 17.6 l/min (interquartile range 12.3–27.0 l/min). All subjects reported thermal discomfort, with two (22.2%) requesting early termination of the experiment. Whilst the degree of rebreathing in this experiment was not sufficient to cause dangerous physiological derangement, the degree of reported thermal discomfort combined with the consequences of entrainment of possibly contaminated air into the hood, pose a risk to wearers in the event of failure.

scholarly journals A Pilot Study on the Association of Mitochondrial Oxygen Metabolism and Gas Exchange During Cardiopulmonary Exercise Testing: Is There a Mitochondrial Threshold?

2020 ◽  
Vol 7 ◽  
Author(s):  
Philipp Baumbach ◽  
Christiane Schmidt-Winter ◽  
Jan Hoefer ◽  
Steffen Derlien ◽  
Norman Best ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Cardiopulmonary Exercise Testing ◽  
Oxygen Metabolism ◽  
Capillary Blood ◽  
Blood Gas ◽  
Cardiopulmonary Exercise ◽  
Blood Gas Analyses ◽  
End Tidal

Background: Mitochondria are the key players in aerobic energy generation via oxidative phosphorylation. Consequently, mitochondrial function has implications on physical performance in health and disease ranging from high performance sports to critical illness. The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) allows in vivo measurements of mitochondrial oxygen tension (mitoPO2). Hitherto, few data exist on the relation of mitochondrial oxygen metabolism and ergospirometry-derived variables during physical performance. This study investigates the association of mitochondrial oxygen metabolism with gas exchange and blood gas analysis variables assessed during cardiopulmonary exercise testing (CPET) in aerobic and anaerobic metabolic phases.Methods: Seventeen volunteers underwent an exhaustive CPET (graded multistage protocol, 50 W/5 min increase), of which 14 were included in the analysis. At baseline and for every load level PpIX-TSLT-derived mitoPO2 measurements were performed every 10 s with 1 intermediate dynamic measurement to obtain mitochondrial oxygen consumption and delivery (mitoV.O2, mitoD.O2). In addition, variables of gas exchange and capillary blood gas analyses were obtained to determine ventilatory and lactate thresholds (VT, LT). Metabolic phases were defined in relation to VT1 and VT2 (aerobic: &lt;VT1, aerobic-anaerobic transition: ≥VT1 and &lt;VT2 and anaerobic: ≥VT2). We used linear mixed models to compare variables of PpIX-TSLT between metabolic phases and to analyze their associations with variables of gas exchange and capillary blood gas analyses.Results: MitoPO2 increased from the aerobic to the aerobic-anaerobic phase followed by a subsequent decline. A mitoPO2 peak, termed mitochondrial threshold (MT), was observed in most subjects close to LT2. MitoD.O2 increased during CPET, while no changes in mitoV.O2 were observed. MitoPO2 was negatively associated with partial pressure of end-tidal oxygen and capillary partial pressure of oxygen and positively associated with partial pressure of end-tidal carbon dioxide and capillary partial pressure of carbon dioxide. MitoD.O2 was associated with cardiovascular variables. We found no consistent association for mitoV.O2.Conclusion: Our results indicate an association between pulmonary respiration and cutaneous mitoPO2 during physical exercise. The observed mitochondrial threshold, coinciding with the metabolic transition from an aerobic to an anaerobic state, might be of importance in critical care as well as in sports medicine.

Ventilatory Response to Hypoxia in Humans

1996 ◽  
Vol 85 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Albert Dahan ◽  
Elise Sarton ◽  
Maarten van den Elsen ◽  
Jack van Kleef ◽  
Luc Teppema ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Carbon Dioxide Concentration ◽  
Detectable Effect ◽  
Hypoxic Ventilatory Response ◽  
Anesthetic Agents ◽  
Carotid Bodies ◽  
End Tidal

Background At low dose, the halogenated anesthetic agents halothane, isoflurane, and enflurane depress the ventilatory response to isocapnic hypoxia in humans. In the current study, the influence of subanesthetic desflurane (0.1 minimum alveolar concentration [MAC]) on the isocapnic hypoxic ventilatory response was assessed in healthy volunteers during normocapnia and hypercapnia. Methods A single hypoxic ventilatory response was obtained at each of 4 target end-tidal partial pressure of oxygen concentrations: 75, 53, 44, and 38 mmHg, before and during 0.1 MAC desflurane administration. Fourteen subjects were tested at a normal end-tidal partial pressure of carbon dioxide (43 mmHg), with 9 subjects tested at an end-tidal carbon dioxide concentration of 49 mmHg (hypercapnia). The hypoxic sensitivity (S) was computed as the slope of the linear regression of inspired minute ventilation (V1) on (100-SPO2). Values are mean +/- SE. Results Sensitivity was unaffected by desflurane during normocapnia (control: S = 0.45 +/- 0.07 l.min-1.%-1 vs. 0.1 MAC desflurane: S = 0.43 +/- 0.09 l.min-1.%-1). With hypercapnia S decreased by 30% during desflurane inhalation (control: S = 0.74 +/- 0.09 l.min-1.%-1 vs. 0.1 MAC desflurane: S = 0.53 +/- 0.06 l.min-1.%-1; P &lt; 0.05). Conclusions On the basis of the data, subanesthetic desflurane has no detectable effect on the normocapnic hypoxic ventilatory response sensitivity. However, the carbon dioxideinduced augmentation of the hypoxic response was reduced. This indicates that subanesthetic desflurane effects the chemoreceptors at the carotid bodies.

PULMONARY FUNCTION, DEDUCED FROM URINARY NITROGEN TENSIONS

PEDIATRICS ◽  
1967 ◽  
Vol 40 (6) ◽  
pp. 937-938
Author(s):  
M. E. A.
Keyword(s):  
Carbon Dioxide ◽  
Blood Flow ◽  
Pulmonary Function ◽  
Partial Pressure ◽  
Urine Sample ◽  
Pulmonary Blood Flow ◽  
Lung Perfusion ◽  
Alveolar Ventilation ◽  
Arterial Oxygen ◽  
Urinary Nitrogen

THE elegant studies reported by Led-better, Homma, and Farhi in this issue are entitled `'Readjustment in Distribution of Alveolar Ventilation and Lung Perfusion in the Newborn." It must come as a great surprise to the reader to discover that the only measurement actually made was the partial pressure of nitrogen in the infants' urine. How could one conclude that there were significant imbalances between the distribution of alveolar ventilation and pulmonary blood flow (VA/Q) in the first days of life in normal infants from a urine sample? It is all the more astounding in the light of previous (and seemingly more direct) studies of alveolar-arterial oxygen and carbon dioxide differences which led others to consider the differences largely explained by anatomical right-to-left shunts.

Decreased Carbon Dioxide Sensitivity in Infants of Substance-Abusing Mothers

PEDIATRICS ◽  
1995 ◽  
Vol 95 (6) ◽  
pp. 864-867
Author(s):  
Janet G. Wingkun ◽  
Janet S. Knisely ◽  
Sidney H. Schnoll ◽  
Gary R. Gutcher
Keyword(s):  
Carbon Dioxide ◽  
Tidal Volume ◽  
Minute Ventilation ◽  
Demographic Data ◽  
Substance Abusing ◽  
Quiet Sleep ◽  
Co2 Level ◽  
The Difference ◽  
End Tidal ◽  
Drug Free

Objective. To determine whether there is a demonstrable abnormality in control of breathing in infants of substance-abusing mothers during the first few days of life. Methods. We enrolled 12 drug-free control infants and 12 infants of substance abusing mothers (ISAMs). These infants experienced otherwise uncomplicated term pregnancies and deliveries. The infants were assigned to a group based on the results of maternal histories and maternal and infant urine toxicology screens. Studies were performed during quiet sleep during the first few days of life. We measured heart rate, oxygen saturations via a pulse oximeter, end-tidal carbon dioxide (ET-CO2) level, respiratory rate, tidal volume, and airflow. The chemoreceptor response was assessed by measuring minute ventilation and the ET-CO2 level after 5 minutes of breathing either room air or 4% carbon dioxide. Results. The gestational ages by obstetrical dating and examination of the infants were not different, although birth weights and birth lengths were lower in the group of ISAMs. Other demographic data were not different, and there were no differences in the infants' median ages at the time of study or in maternal use of tobacco and alcohol. The two groups had comparable baseline (room air) ET-CO2 levels, respiratory rates, tidal volumes, and minute ventilation. When compared with the group of ISAMs, the drug-free group had markedly increased tidal volume and minute ventilation on exposure to 4% carbon dioxide. These increases accounted for the difference in sensitivity to carbon dioxide, calculated as the change in minute ventilation per unit change in ET-CO2 (milliliters per kg/min per mm Hg). The sensitivity to carbon dioxide of control infants was 48.66 ± 7.14 (mean ± SE), whereas that of ISAMs was 16.28 ± 3.14. Conclusions. These data suggest that ISAMs are relatively insensitive to challenge by carbon dioxide during the first few days of life. We speculate that this reflects an impairment of the chemoreceptor response.

Ventilatory responses to carbon dioxide at low and high levels of oxygen are elevated after episodic hypoxia in men compared with women

2004 ◽  
Vol 97 (5) ◽  
pp. 1673-1680 ◽  
Author(s):  
Chris Morelli ◽  
M. Safwan Badr ◽  
Jason H. Mateika
Keyword(s):  
Carbon Dioxide ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
High Oxygen ◽  
Set Point ◽  
Ventilatory Responses ◽  
Episodic Hypoxia ◽  
Before And After ◽  
Oxygen Gas ◽  
End Tidal

We hypothesized that the acute ventilatory response to carbon dioxide in the presence of low and high levels of oxygen would increase to a greater extent in men compared with women after exposure to episodic hypoxia. Eleven healthy men and women of similar race, age, and body mass index completed a series of rebreathing trials before and after exposure to eight 4-min episodes of hypoxia. During the rebreathing trials, subjects initially hyperventilated to reduce the end-tidal partial pressure of carbon dioxide (PetCO2) below 25 Torr. Subjects then rebreathed from a bag containing a normocapnic (42 Torr), low (50 Torr), or high oxygen gas mixture (150 Torr). During the trials, PetCO2 increased while the selected level of oxygen was maintained. The point at which minute ventilation began to rise in a linear fashion as PetCO2 increased was considered to be the carbon dioxide set point. The ventilatory response below and above this point was determined. The results showed that the ventilatory response to carbon dioxide above the set point was increased in men compared with women before exposure to episodic hypoxia, independent of the oxygen level that was maintained during the rebreathing trials (50 Torr: men, 5.19 ± 0.82 vs. women, 4.70 ± 0.77 l·min−1·Torr−1; 150 Torr: men, 4.33 ± 1.15 vs. women, 3.21 ± 0.58 l·min−1·Torr−1). Moreover, relative to baseline measures, the ventilatory response to carbon dioxide in the presence of low and high oxygen levels increased to a greater extent in men compared with women after exposure to episodic hypoxia (50 Torr: men, 9.52 ± 1.40 vs. women, 5.97 ± 0.71 l·min−1·Torr−1; 150 Torr: men, 5.73 ± 0.81 vs. women, 3.83 ± 0.56 l·min−1·Torr−1). Thus we conclude that enhancement of the acute ventilatory response to carbon dioxide after episodic hypoxia is sex dependent.

scholarly journals Correlation Between N-Terminal Pro-Brain Natriuretic Peptide Levels and Cardiopulmonary Exercise Testing in Patients With Pre-Capillary Pulmonary Hypertension: A Pilot Study

2020 ◽  
Vol 14 ◽  
pp. 117954842095404
Author(s):  
Sahachat Aueyingsak ◽  
Wilaiwan Khrisanapant ◽  
Upa Kukongviriyapun ◽  
Orapin Pasurivong ◽  
Pailin Ratanawatkul ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Hypertension ◽  
Brain Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Exercise Testing ◽  
Cardiopulmonary Exercise Testing ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Peak Oxygen Uptake ◽  
Cardiopulmonary Exercise ◽  
End Tidal

Background: N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiopulmonary exercise testing (CPET) are useful for severity assessment in patients with pulmonary hypertension (PH). Correlations between these tests in pre-capillary PH patients is less well studied. Methods: We studied 23 patients with pre-capillary PH: 8 with idiopathic pulmonary arterial hypertension (IPAH), 6 with systemic sclerosis-associated PAH (SSc-PAH), and 9 with chronic thromboembolic pulmonary hypertension (CTEPH). Clinical evaluation, NT-proBNP levels, six-minute walking test (6MWT), spirometry, and CPET were evaluated on the same day. Correlation between NT-proBNP levels and CPET parameters were investigated. Results: In all patients, NT-proBNP levels were significantly correlated with peak oxygen uptake (VO2) ( r = −0.47), peak oxygen pulse ( r = −0.43), peak cardiac output (CO) ( r = −0.57), peak end-tidal partial pressure of carbon dioxide (PETCO2) ( r = −0.74), ventilatory equivalent to carbon dioxide (VE/VCO2) at anaerobic threshold (AT) ( r = 0.73), and VE/VCO2 slope ( r = 0.64). Significant correlations between NT-proBNP levels and peak PETCO2 and VE/VCO2 were found in IPAH and CTEPH subgroups, and a significant correlation between NT-proBNP levels and VO2 at AT was found in the CTEPH subgroup. No significant correlation was found in the SSc-PAH subgroup. Conclusion: NT-proBNP levels were significantly correlated with CPET parameters in patients with IPAH and CTEPH subgroups, but not in SSc-PAH subgroup. A further study with larger population is required to confirm these preliminary findings.

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