A new technique to analyse threshold-intensities based on time dependent change-points in the ratio of minute ventilation and end-tidal partial pressure of carbon-dioxide production

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.

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

Pulmonary Circulation ◽

10.1177/20458940211059713 ◽

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 Ã PeakPETCO2 + 0.127ÃFEV1/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.

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Effects of Varied Vocal Intensity on Ventilation and Energy Expenditure in Women and Men

Journal of Speech Language and Hearing Research ◽

10.1044/jslhr.4102.239 ◽

1998 ◽

Vol 41 (2) ◽

pp. 239-248 ◽

Cited By ~ 30

Author(s):

Bridget A. Russell ◽

Frank J. Cerny ◽

Elaine T. Stathopoulos

Keyword(s):

Carbon Dioxide ◽

Steady State ◽

Energy Expenditure ◽

Minute Ventilation ◽

Face Mask ◽

Carbon Dioxide Production ◽

Quiet Breathing ◽

Energy Expenditures ◽

Ventilatory Responses ◽

End Tidal

This study was completed to determine how ventilatory responses change by means of speech reading at three different sound pressure levels (SPL) as compared to quiet breathing prior to each task. The energy required to alter SPL was also studied and compared to energy expenditures during a quiet breathing condition. Twenty-four adults (12 women, 12 men) were studied while reading a standard passage at low, comfortable, and high SPLs for 7 minutes with quiet breathing periods between each task to achieve respiratory steady state and serve as a control to which the reading tasks were compared. The last 2 minutes of exhaled air for all speaking and quiet breathing tasks were collected using a Hans Rudolph mouth breathing face mask. A Sensor Medics V max 29 TM series diagnostic instrument system measured all ventilatory responses and energy expenditures. Volume and timing alterations in ventilation were characterized by measuring tidal volume (V T ), inspiratory time (T I ), inspiratory flow rate (V T /T I ), and expiratory time (T E ). Average ventilation, energy expenditure, and adequacy of ventilation were measured using minute ventilation (V W E ), oxygen consumption V W O 2 ), carbon dioxide production (V W CO 2 ), and partial pressure of end-tidal carbon dioxide (end-tidal PET CO2 ). Results indicated volume, timing, ventilation, and energy expenditure values remained closest to quiet breathing values for the comfortable SPL. Volume, ventilation, and energy expenditure were significantly greater for the high SPL and lower for the low SPL, compared to the baseline steady state, indicating that the low SPL causes a ventilatory deficit that was found to be paid back at the end of the speech task during the quiet breathing period. These results demonstrate that an individual's comfortable SPL is the least energyrequiring way to speech breathe. As SPL rises above or below comfortable SPL, speech breathing requires more energy.

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Minute ventilation/carbon dioxide production in chronic heart failure

European Respiratory Review ◽

10.1183/16000617.0141-2020 ◽

2021 ◽

Vol 30 (159) ◽

pp. 200141

Author(s):

Piergiuseppe Agostoni ◽

Susanna Sciomer ◽

Pietro Palermo ◽

Mauro Contini ◽

Beatrice Pezzuto ◽

...

Keyword(s):

Heart Failure ◽

Carbon Dioxide ◽

Chronic Heart Failure ◽

Dead Space ◽

Minute Ventilation ◽

Carbon Dioxide Production ◽

Absolute Number ◽

Prognostic Scores ◽

And Gender ◽

End Tidal

In chronic heart failure, minute ventilation (V′E) for a given carbon dioxide production (V′CO2) might be abnormally high during exercise due to increased dead space ventilation, lung stiffness, chemo- and metaboreflex sensitivity, early metabolic acidosis and abnormal pulmonary haemodynamics. The V′Eversus V′CO2 relationship, analysed either as ratio or as slope, enables us to evaluate the causes and entity of the V′E/perfusion mismatch. Moreover, the V′E axis intercept, i.e. when V′CO2 is extrapolated to 0, embeds information on exercise-induced dead space changes, while the analysis of end-tidal and arterial CO2 pressures provides knowledge about reflex activities. The V′Eversus V′CO2 relationship has a relevant prognostic power either alone or, better, when included within prognostic scores. The V′Eversus V′CO2 slope is reported as an absolute number with a recognised cut-off prognostic value of 35, except for specific diseases such as hypertrophic cardiomyopathy and idiopathic cardiomyopathy, where a lower cut-off has been suggested. However, nowadays, it is more appropriate to report V′Eversus V′CO2 slope as percentage of the predicted value, due to age and gender interferences. Relevant attention is needed in V′Eversus V′CO2 analysis in the presence of heart failure comorbidities. Finally, V′Eversus V′CO2 abnormalities are relevant targets for treatment in heart failure.

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Ventilatory Response to Hypoxia in Humans

Anesthesiology ◽

10.1097/00000542-199607000-00009 ◽

1996 ◽

Vol 85 (1) ◽

pp. 60-68 ◽

Cited By ~ 34

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 < 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.

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Reduction of Time-Dependent Change of Coercive Force and Iron(II) Content by Silica and Aluminum Hydrate Coating onto Co-magnetite Fine Particles.

KAGAKU KOGAKU RONBUNSHU ◽

10.1252/kakoronbunshu.25.361 ◽

1999 ◽

Vol 25 (3) ◽

pp. 361-366 ◽

Cited By ~ 5

Author(s):

KAZUYUKI HAYASHI ◽

KEISUKE IWASAKI ◽

YASUYUKI TANAKA ◽

HIROKO MORII

Keyword(s):

Coercive Force ◽

Fine Particles ◽

Time Dependent ◽

Dependent Change ◽

Aluminum Hydrate ◽

Time Dependent Change

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Decreased Carbon Dioxide Sensitivity in Infants of Substance-Abusing Mothers

PEDIATRICS ◽

10.1542/peds.95.6.864 ◽

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.

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

Journal of Applied Physiology ◽

10.1152/japplphysiol.00541.2004 ◽

2004 ◽

Vol 97 (5) ◽

pp. 1673-1680 ◽

Cited By ~ 48

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.

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