Chemoreflex control of breathing during wakefulness in healthy men and women

2005 ◽  
Vol 98 (3) ◽  
pp. 822-828 ◽  
Author(s):  
Dennis Jensen ◽  
Larry A. Wolfe ◽  
Denis E. O'Donnell ◽  
Gregory A. L. Davies
Keyword(s):  
Vital Capacity ◽  
Ventilatory Response ◽  
Follicular Phase ◽  
Control Of Breathing ◽  
Gas Mixture ◽  
Men And Women ◽  
Healthy Men ◽  
Chemoreflex Sensitivity ◽  
End Tidal ◽  
Peripheral Chemoreflex

This study used a modified CO2 rebreathing procedure to examine the effect of gender on the chemoreflex control of breathing during wakefulness in healthy men ( n = 14) and women ( n = 14). Women were tested in the follicular phase of the menstrual cycle. During rebreathing trials, subjects hyperventilated to reduce the partial pressure of end-tidal CO2 (PetCO2) below 25 Torr and were then switched to a rebreathing bag containing a normocapnic hypoxic or hyperoxic gas mixture. During the trial, PetCO2 increased, while O2 was maintained at a constant level. The point at which ventilation began to rise as PetCO2 increased was identified as the ventilatory recruitment threshold (VRT). Ventilation below the VRT was measured, and the slope of the ventilatory response above the VRT was determined. Gender had no effect on the hyperoxic or hypoxic VRT for CO2. Central chemoreflex sensitivity was significantly greater in men than women but not after correction for forced vital capacity. Measures of peripheral chemoreflex sensitivity were similar between genders. However, the slope of the tidal volume (Vt) response to hyperoxic and hypoxic CO2 rebreathing (corrected and uncorrected) was greater in men than women, respectively. We conclude that central chemoreflex sensitivity is greater in men compared with women as reflected by differences in ventilatory (uncorrected) and Vt (corrected and uncorrected) responses to CO2. However, gender has no significant effect on the central chemoreflex VRT for CO2. The peripheral chemoreflex control of breathing during wakefulness is similar between men and women.

Postnatal maturation of peripheral chemoreceptor ventilatory response to O2 and CO2 in newborn lambs

1996 ◽  
Vol 80 (6) ◽  
pp. 1928-1933 ◽  
Author(s):  
E. Canet ◽  
I. Kianicka ◽  
J. P. Praud
Keyword(s):  
Carotid Body ◽  
Ventilatory Response ◽  
Time Frame ◽  
Peripheral Chemoreceptor ◽  
Postnatal Maturation ◽  
Time Courses ◽  
End Tidal ◽  
Peripheral Chemoreflex ◽  
End Tidal Co2

Although studies on lambs have shown that carotid body sensitivity to O2 is reset postnatally, it is still unknown whether O2 and CO2 peripheral chemoreflexes undergo parallel postnatal maturation. The present study was designed to analyze maturation of O2 and CO2 peripheral chemoreflexes in 10 lambs at < 24 h and at 12 days of age. We measured the ventilatory (VE) response to three tidal breaths of pure N2 or 13% CO2 in air. Overall, the N2 peripheral chemoreflex increased significantly with maturation [VE/end-tidal O2 (ml.min-1.kg-1.Torr-1) = 2.94 +/- 0.91 at < 24 h vs. 5.13 +/- 0.59 at 12 days, P < 0.05], whereas the CO2 peripheral chemoreflex did not change (VE/end-tidal CO2 = 7.04 +/- 0.98 at < 24 h vs. 7.75 +/- 1.07 at 12 days, not significant). We conclude that the CO2 peripheral chemoreflex does not change in awake lambs within the time frame studied, in contrast to a marked postnatal maturation of the O2 peripheral chemoreflex. The different time courses of O2 and CO2 peripheral chemoreflex maturation support the concept that carotid body sensitivities to O2 and CO2 do not depend on the same basic mechanisms.

An assessment of nasal functions in control of breathing

1988 ◽  
Vol 65 (4) ◽  
pp. 1520-1524 ◽  
Author(s):  
Y. Tanaka ◽  
T. Morikawa ◽  
Y. Honda
Keyword(s):  
Steady State ◽  
Dead Space ◽  
Airway Resistance ◽  
Breathing Pattern ◽  
Ventilatory Response ◽  
Control Of Breathing ◽  
Mouth Breathing ◽  
Occlusion Pressure ◽  
Ventilatory Responses ◽  
End Tidal

Breathing pattern and steady-state CO2 ventilatory response during mouth breathing were compared with those during nose breathing in nine healthy adults. In addition, the effect of warming and humidification of the inspired air on the ventilatory response was observed during breathing through a mouthpiece. We found the following. 1) Dead space and airway resistance were significantly greater during nose than during mouth breathing. 2) The slope of CO2 ventilatory responses did not differ appreciably during the two types of breathing, but CO2 occlusion pressure response was significantly enhanced during nose breathing. 3) Inhalation of warm and humid air through a mouthpiece significantly depressed CO2 ventilation and occlusion pressure responses. These results fit our observation that end-tidal PCO2 was significantly higher during nose than during mouth breathing. It is suggested that a loss of nasal functions, such as during nasal obstruction, may result in lowering of CO2, fostering apneic spells during sleep.

Sevoflurane-induced Reduction of Hypoxic Drive Is Sex-independent 

1999 ◽  
Vol 90 (5) ◽  
pp. 1288-1293 ◽  
Author(s):  
Elise Sarton ◽  
Minke van der Wal ◽  
Diederik Nieuwenhuijs ◽  
Luc Teppema ◽  
James L. Robotham ◽  
...  
Keyword(s):  
Bispectral Index ◽  
Low Dose ◽  
Ventilatory Response ◽  
Carbon Dioxide Tension ◽  
Opioid Agonist ◽  
Men And Women ◽  
Ventilatory Responses ◽  
Inhalational Anesthetic ◽  
Ventilatory Effects ◽  
End Tidal

Background Although the mu-opioid agonist morphine affects ventilatory control in men and women in different ways, no data exist regarding the influence of sex on the ventilatory effects of inhalational anesthetics. The authors compared the effect of sevoflurane on the ventilatory response to isocapnic hypoxia in healthy young men and women. Methods Breath-to-breath ventilatory responses to hypoxic steps (number of hypoxic steps, four-six; duration, 3 min; end-tidal oxygen tension, approximately 50 mmHg; end-tidal carbon dioxide tension clamped at approximately 4 mmHg above resting values) were assessed in nine men and nine women without and with low-dose sevoflurane (end-tidal concentration, 0.25%). The bispectral index of the electroencephalogram was measured concomitantly. Results Sevoflurane reduced the hypoxic ventilatory sensitivity significantly in both sexes (men: control, 0.62 +/- 0.17 vs. sevoflurane, 0.38 +/- 0.19 l x min(-1) x %(-1); women: control, 0.52 +/- 0.30 vs. sevoflurane, 0.34 +/- 0.15 l x min(-1) x %(-1)). Sevoflurane-induced reductions of the hypoxic responses were not different in the men and women. During sevoflurane inhalation, the bispectral index values decreased equally in men and women. Conclusion In contrast to morphine, the influence of a low dose of the inhalational anesthetic sevoflurane on the ventilatory response to hypoxia is independent of sex.

The Ventilatory Response to Hypoxia Below the Carbon Dioxide Threshold

1997 ◽  
Vol 22 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Theodore Rapanos ◽  
James Duffin
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Ventilatory Response ◽  
Pressure Threshold ◽  
Partial Pressures ◽  
Progressive Hypoxia ◽  
End Tidal ◽  
Peripheral Chemoreflex ◽  
Ventilatory Response To Hypoxia ◽  
Lower Carbon

The ventilatory response to acute progressive hypoxia below the carbon dioxide threshold using rebreathing was investigated. Nine subjects rebreathed after 5 min of hyperventilation to lower carbon dioxide stores. The rebreathing bag initially contained enough carbon dioxide to equilibrate alveolar and arterial partial pressures of carbon dioxide to the lowered mixed venous partial pressure (≈ 30 mmHg), and enough oxygen to establish a chosen end-tidal partial pressure (50-70 mmHg), within one circulation time. During rebreathing, end-tidal partial pressure of carbon dioxide increased while end-tidal partial pressure of oxygen fell. Ventilation increased linearly with end-tidal carbon dioxide above a mean end-tidal partial pressure threshold of 39 ± 2.7 mmHg. Below this peripheral-chemoreflex threshold, ventilation did not increase, despite a progressive fall in end-tidal oxygen partial pressure to a mean of 37 ± 4.1 mmHg. In Conclusion, hypoxia does not stimulate ventilation when carbon dioxide is below its peripheral-chemoreflex threshold. Key words: peripheral chemoreflex, rebreathing technique, hyperventilation

Dynamics of the Ventilatory Response to Step Changes in End-Tidal PCO2 in Older Humans

1997 ◽  
Vol 22 (4) ◽  
pp. 368-383 ◽  
Author(s):  
Marc J. Poulin ◽  
David A. Cunningham ◽  
Donald H. Paterson
Keyword(s):  
Carbon Dioxide ◽  
Ventilatory Response ◽  
Older Men ◽  
Young Group ◽  
Control Of Breathing ◽  
Ventilatory Responses ◽  
Key Words Ageing ◽  
Younger Men ◽  
End Tidal ◽  
Mild Hypoxia

The purpose of this study was to examine the ventilatory response to carbon dioxide (CO2) in young and older men. Six square-wave steps of end-tidal CO2 (PETCO2) were administered in euoxia (PETO2 = 100 torr), hyperoxia (PETO2 = 500 torr), and mild hypoxia (PETO2 = 60 torr) The peripheral and central chemoreflex loops were described by three parameters including a gain (gp and gc), time constant of the response(τp, τc), and a time delay (Tp, Tc), respectively. The young and older men showed similar characteristics for Tp and Tc, with Tp, being 3 to 5 s shorter than Tc. In hypoxia, the ventilatory responses of the old group were characterised by a significantly smaller gc and a smaller gp. In hypoxia, τc was significantly shortened from its euoxic value in the young group, but not in the old group. Thus, this study demonstrated that in older men, the ventilatory responses to CO2 in euoxia and hyperoxia are similar to younger men, while in hypoxia the ventilatory responses are characterised by smaller gain terms. Key words: ageing, hypercapnia, hypoxia, hyperoxia, control of breathing

scholarly journals Acute inorganic nitrate supplementation and the hypoxic ventilatory response in patients with obstructive sleep apnea

2020 ◽  
Author(s):  
Joshua M. Bock ◽  
Brady E. Hanson ◽  
Thomas F. Asama ◽  
Andrew J. Feider ◽  
Satoshi Hanada ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Ventilatory Response ◽  
High Dose ◽  
Inorganic Nitrate ◽  
Obstructive Sleep ◽  
Chemoreflex Sensitivity ◽  
Nitrate Supplementation ◽  
High Doses ◽  
Peripheral Chemoreflex

Patients with obstructive sleep apnea (OSA) have increased cardiovascular disease risk largely attributable to hypertension. Heightened peripheral chemoreflex sensitivity (i.e., exaggerated responsiveness to hypoxia) facilitates hypertension in these patients. Nitric oxide blunts the peripheral chemoreflex and patients with OSA have reduced nitric oxide bioavailability. We therefore investigated the dose-dependent effects of acute inorganic nitrate supplementation (beetroot juice), an exogenous nitric oxide source, on blood pressure and cardiopulmonary responses to hypoxia in patients with OSA using a randomized, double-blind, placebo-controlled crossover design. Fourteen patients with OSA (53±10years, 29.2±5.8kg/m2, apnea-hypopnea index=17.8±8.1, 43%F) completed three visits. Resting brachial blood pressure, as well as cardiopulmonary responses to inspiratory hypoxia, were measured before, and two hours after, acute inorganic nitrate supplementation (~0.10mmol [placebo], 4.03mmol [low-dose], and 8.06mmol [high-dose]). Placebo did not increase either plasma [nitrate] (30±52 to 52±23μM, P=0.26) or [nitrite] (266±153 to 277±164nM, P=0.21); however, both increased following low-(29±17 to 175±42μM, 220±137 to 514±352nM) and high-doses (26±11 to 292±90μM, 248±155 to 738±427nM, respectively, P<0.01 for all). Following placebo, systolic blood pressure increased (120±9 to128±10mmHg, P<0.05) whereas no changes were observed following low-(121±11 to 123±8mmHg, P=0.19) or high-dose (124±13 to 124±9mmHg, P=0.96). The peak ventilatory response to hypoxia increased following placebo (3.1±1.2 to 4.4±2.6L/min, P<0.01) but not low-(4.4±2.4 to 5.4±3.4L/min, P=0.11) or high-doses (4.3±2.3 to 4.8±2.7L/min, P=0.42). Inorganic nitrate did not change the heart rate responses to hypoxia (beverage-by-time P=0.64). Acute inorganic nitrate supplementation appears to blunt an early-morning rise in systolic blood pressure potentially through suppression of peripheral chemoreflex sensitivity in patients with OSA.

Biological Aspects of Breath-Alcohol Analysis

1974 ◽  
Vol 20 (2) ◽  
pp. 294-299 ◽  
Author(s):  
Kurt M Dubowski
Keyword(s):  
Forced Vital Capacity ◽  
Rational Design ◽  
Vital Capacity ◽  
Men And Women ◽  
Healthy Men ◽  
Breath Sampling ◽  
Breath Alcohol ◽  
Delivery Pressure ◽  
Sampling Systems ◽  
Biological Aspects

Abstract We studied several relevant biological aspects of breath-alcohol analysis in 55 healthy men and women, after alcohol ingestion and during breath-alcohol analysis with a typical 4th-generation instrument. We measured breath volumes, delivery pressures, and end-expiratory temperatures, with the following findings: End-expiratory temperature, 32.41-35.69 °C (mean, 34.53 °C); forced vital capacity, 1825-6550 ml (mean, 4038 ml); maximum expiration after normal inspiration, 1180-4550 ml ( mean, 2730 ml); breath delivery pressure into a prototype Borg-Warner Model P-7 breath-alcohol apparatus, 8-50 inches H2O (mean, 21.3). These data and other pertinent findings from this study should assist in more rational design of breath-sampling systems in forthcoming breath-alcohol instruments and in developing valid procedures for their use.

Single breath of CO2 as a clinical test of the peripheral chemoreflex

1988 ◽  
Vol 64 (1) ◽  
pp. 84-89 ◽  
Author(s):  
P. A. McClean ◽  
E. A. Phillipson ◽  
D. Martinez ◽  
N. Zamel
Keyword(s):  
Ventilatory Response ◽  
Clinical Test ◽  
Peripheral Chemoreceptor ◽  
Single Breath ◽  
The Difference ◽  
Safety Considerations ◽  
End Tidal ◽  
Peripheral Chemoreflex ◽  
Peak Increase ◽  
Healthy Females

Peripheral chemoreceptor responsiveness is usually examined clinically by hypoxic testing, but the usefulness of this approach is limited by safety considerations, and the interpretation of results may be confounded by the direct central nervous system effects of hypoxia. Therefore we examined the single-breath (SB) CO2 test to determine its reproducibility and applicability as a clinical test of peripheral chemoreceptor function. The technique involved the inhalation of a SB of 13% CO2 in air. The ventilatory response was determined from the increase in ventilation (VE) during the first 20 s after the test breath and from the difference in end-tidal PCO2 between the test breath and preceding control breaths. The peak increase in VE occurred during the second or third breath after the test breath, corresponding to a delay of approximately 10 s. The mean of 10 SB tests administered at 2- to 3-min intervals was taken as the subject's response. Five healthy subjects were tested in this manner on each of 6 consecutive days with the response having an interday coefficient of variation of 25 +/- 6% (SD). The response in 26 healthy females (aged 22-61 yr) was 0.32 +/- 0.11 l.min-1.Torr-1, and in 26 healthy males (aged 24-69 yr) the response was 0.38 +/- 0.14 (P NS). No significant correlation was found between the age of the subjects and their ventilatory response. Thirty-six of the subjects also underwent hyperoxic CO2 rebreathing tests, the response to which is dependent on central chemoreceptor function. No correlation was found between rebreathing and SB tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Respiratory Sites of Action of Propofol

2001 ◽  
Vol 95 (4) ◽  
pp. 889-895 ◽  
Author(s):  
Diederik Nieuwenhuijs ◽  
Elise Sarton ◽  
Luc J. Teppema ◽  
Erik Kruyt ◽  
Ida Olievier ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ventilatory Response ◽  
Binary Sequence ◽  
Total Duration ◽  
Carbon Dioxide Concentration ◽  
Central Component ◽  
End Tidal ◽  
Sites Of Action ◽  
Peripheral Chemoreflex ◽  
Carbon Dioxide Sensitivity

Background Propofol has a depressant effect on metabolic ventilatory control, causing depression of the ventilatory response to acute isocapnic hypoxia, a response mediated via the peripheral chemoreflex loop. In this study, the authors examined the effect of sedative concentrations of propofol on the dynamic ventilatory response to carbon dioxide to obtain information about the respiratory sites of action of propofol. Methods In 10 healthy volunteers, the end-tidal carbon dioxide concentration was varied according to a multifrequency binary sequence that involved 13 steps into and 13 steps out of hypercapnia (total duration, 1,408 s). In each subject, two control studies, two studies at a plasma target propofol concentration of 0.75 microg/ml (P(low)), and two studies at a target propofol concentration of 1.5 microg/ml (P(high)) were performed. The ventilatory responses were separated into a fast peripheral component and a slow central component, characterized by a time constant, carbon dioxide sensitivity, and apneic threshold. Values are mean +/- SD. Results Plasma propofol concentrations were approximately 0.5 microg/ml for P(low) and approximately 1.3 mg/ml for P(high), Propofol reduced the central carbon dioxide sensitivity from 1.5 +/- 0.4 to 1.2 +/- 0.3 (P(low); P &lt; 0.01 vs. control) and 0.9 +/- 0.1 l x min(-1) x mmHg(-1) (P(high); P &lt; 0.001 vs. control). The peripheral carbon dioxide sensitivity remained unaffected by propofol (control, 0.5 +/- 0.3; P(low), 0.5 +/- 0.2; P(high), 0.5 +/- 0.2 l x min(-1) x mmHg(-1)). The apneic threshold was reduced from 36.3 +/- 2.7 (control) to 35.0 +/- 2.1 (P(low); P &lt; 0.01 vs. control) and to 34.6 +/- 1.9 mmHg (P(high); P &lt; 0.01 vs. control). Conclusions Sedative concentrations of propofol have an important effect on the control of breathing, showing depression of the ventilatory response to hypercapnia. The depression is attributed to an exclusive effect within the central chemoreflex loop at the central chemoreceptors. In contrast to low-dose inhalational anesthetics, the peripheral chemoreflex loop, when stimulated with carbon dioxide, remains unaffected by propofol.

Dynamic response of the peripheral chemoreflex loop to changes in end-tidal O2

1991 ◽  
Vol 71 (3) ◽  
pp. 1123-1128 ◽  
Author(s):  
A. Berkenbosch ◽  
J. DeGoede ◽  
D. S. Ward ◽  
C. N. Olievier ◽  
J. VanHartevelt
Keyword(s):  
Time Constant ◽  
Ventilatory Response ◽  
Slow Component ◽  
Response Dynamics ◽  
Exponential Functions ◽  
End Tidal ◽  
Alpha Chloralose ◽  
Peripheral Chemoreflex ◽  
The Brain ◽  
End Tidal Co2

We studied the peripheral ventilatory response dynamics to changes in end-tidal O2 tension (PETO2) in 13 cats anesthetized with alpha-chloralose-urethan. The arterial O2 tension in the medulla oblongata was kept constant using the technique of artificial perfusion of the brain stem. At constant end-tidal CO2 tension, 72 ventilatory on-responses due to stepwise changes in PETO2 from hyperoxia (45–55 kPa) to hypoxia (4.7–9.0 kPa) and 62 ventilatory off-responses due to changes from hypoxia to hyperoxia were assessed. We fitted two exponential functions with the same time delay to the breath-by-breath ventilation and found a fast and a slow component in 85% of the ventilatory on-responses and in 76% of the off-responses. The time constant of the fast component of the ventilatory on-response was 1.6 +/- 1.5 (SD) s, and that of the off-response was 2.4 +/- 1.3 s; the gain of the on-response was smaller than that of the off-response (P = 0.020). For the slow component, the time constant of the on-response (72.6 +/- 36.4 s) was larger (P = 0.028) than that of the off-response (43.7 +/- 28.3 s), whereas the gain of the on-response exceeded that of the off-response (P = 0.031). We conclude that the ventilatory response of the peripheral chemoreflex loop to stepwise changes in PETO2 contains a fast and a slow component.

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