Postnatal maturation of respiration in intact and carotid body-chemodenervated lambs

1985 ◽  
Vol 59 (3) ◽  
pp. 869-874 ◽  
Author(s):  
M. A. Bureau ◽  
J. Lamarche ◽  
P. Foulon ◽  
D. Dalle
Keyword(s):  
Tidal Volume ◽  
Respiratory Rate ◽  
Carotid Body ◽  
Minute Ventilation ◽  
Inspiratory Flow ◽  
Occlusion Pressure ◽  
Inspiratory Time ◽  
Arterial Pco2 ◽  
Postnatal Maturation ◽  
Arterial Po2

The contribution of the carotid body chemoreceptor to postnatal maturation of breathing was evaluated in lambs from 7 to 70 days of age. The study was conducted by comparing the eupneic ventilation and resting pneumograms in intact conscious lambs with those of lambs that were carotid body chemodenervated (CBD) at birth. In comparison to the 1-wk-old intact lambs, the CBD lambs had significant decreases in minute ventilation (VE, 313 vs. 517 ml/kg), tidal volume (VT, 7.2 vs. 10.5 ml/kg), respiratory rate (f, 44 vs. 51 breaths/min), and occlusion pressure (P0.1, 2.8 vs. 7.2 cmH2O). Arterial PO2's were 59 vs. 75 Torr (P less than 0.05) and arterial PCO2's 47 vs. 36 Torr (P less than 0.05), respectively, in CBD and intact lambs. In intact lambs from 7 to 70 days, resting VE decreased progressively from 517 to 274 ml/kg (P less than 0.01) due to a fall in VT, mean inspiratory flow (VT/TI), and f, whereas the ratio of inspiratory time to total breath duration remained constant. P0.1 decreased from 7.2 to 3.9 cmH2O from 7 to 42 days. In contrast the CBD lambs experienced only minimal changes in VE, VT, VT/TI, and f during the same period. VE only decreased from 313 to 218 and P0.1 from 2.8 to 2.4 cmH2O. In contrast to that of intact lambs the resting pneumogram of CBD lambs remained relatively fixed from 7 to 70 days. Three CBD lambs died unexpectedly, without apparent cause, in the 4th and 5th wk of life.

Predominant role of peripheral chemoreceptors in the termination of apnea in maturing newborn lambs

1996 ◽  
Vol 80 (3) ◽  
pp. 892-898 ◽  
Author(s):  
C. Delacourt ◽  
E. Canet ◽  
M. A. Bureau
Keyword(s):  
Carotid Body ◽  
Pco2 Level ◽  
Peripheral Chemoreceptor ◽  
Arterial Pco2 ◽  
Postnatal Maturation ◽  
Body Function ◽  
Life Threatening ◽  
Prolonged Apnea ◽  
Arterial Po2

Apneas are very common and normal in newborns but may become life threatening if they are not terminated appropriately. The aim of this study in newborn lambs was to investigate the influence on apnea termination of postnatal maturation, peripheral chemoreceptor function, and hypoxia. Apneas were induced by passive hyperventilation at varying inspired O2 fraction levels. The apnea termination threshold PCO2 (PATTCO2) was defined as the arterial PCO2 value at the first breath after the apnea. Three groups of awake intubated lambs were studied: 1) intact lambs tested at both 1 and 15 days of life, 2) intact 1-day-old lambs with central tissue hypoxia induced by CO inhalation, and 3) 1-day-old lambs with carotid body denervation (CBD). In individual lambs and regardless of age and carotid body function, there was a PO2-PCO2 response curve that was a determinant for the termination of an apnea. PATTCO2 invariably increased when arterial PO2 increased, regardless of age. During hypoxia and normoxia, PATTCO2 was significantly lower in 15-day-old lambs compared with 1-day-old lambs. No difference was seen during hyperoxia. PATTCO2 values were shifted to higher levels after carotid body removal. Finally, hypoxia induced by either a low inspired O2 fraction or CO inhalation consistently failed to induce a depressive effect on the PATTCO2 even in CBD lambs. In conclusion, in awake newborn lambs, the PCO2 level for apnea termination changed with postnatal age, and carotid body function was essential in lowering PATTCO2, thus protecting the lambs against prolonged apnea. Furthermore, hypoxia consistently failed to depress the reinitiation of breathing after apnea, even in CBD lambs.

Diaphragm and lung afferents contribute to inspiratory load compensation in awake ponies

1994 ◽  
Vol 76 (3) ◽  
pp. 1330-1339 ◽  
Author(s):  
H. V. Forster ◽  
T. F. Lowry ◽  
L. G. Pan ◽  
B. K. Erickson ◽  
M. J. Korducki ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Treadmill Exercise ◽  
Minute Ventilation ◽  
Inspiratory Time ◽  
Arterial Pco2 ◽  
Load Compensation ◽  
Expiratory Time ◽  
Inspiratory Load

We determined the effect of pulmonary vagal (hilar nerve) denervation (HND) and diaphragm deafferentation (DD) on inspiratory load compensation. We studied awake intact (I; n = 10), DD (n = 5), HND (n = 4), and DD+HND (n = 7) ponies at rest and during mild (1.8 mph, 5% grade) and moderate (1.8 mph, 15% grade) treadmill exercise before, during, and after resistance of the inspiratory circuit was increased from approximately 1.5 to approximately 20 cmH2O.l–1.s. During the first loaded breath in I ponies at rest, inspiratory time (TI) increased, expiratory time decreased, and inspiratory drive increased. There were minimal changes after the first breath, and inspiratory minute ventilation (VI) and arterial PCO2 did not change (P > 0.10) from control values. On the first loaded breath during exercise, TI increased but inspiratory drive either did not change or decreased from control values. TI and drive increased after the first breath, but the increases were insufficient to maintain VI and arterial PCO2 at control levels. First-breath load compensation remained after DD, HND, and DD+HND, but after DD+HND tidal volume and VI were compensated 5–10% less (P < 0.05) than in I ponies. In all groups inspiratory drive, tidal volume, and VI were markedly augmented on the first breath after loading was terminated with a gradual return toward control. We conclude that diaphragm and pulmonary afferents contribute to but are not essential for inspiratory load compensation in awake ponies.

Postnatal maturation of the respiratory response to O2 in awake newborn lambs

1982 ◽  
Vol 52 (2) ◽  
pp. 428-433 ◽  
Author(s):  
M. A. Bureau ◽  
R. Begin
Keyword(s):  
Tidal Volume ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
The Other ◽  
Respiratory Response ◽  
Occlusion Pressure ◽  
Peripheral Chemoreceptors ◽  
Postnatal Maturation ◽  
Early Change ◽  
Lower Response

The present study was designed to analyze maturation of the respiratory response to hypoxia and hyperoxia in 41 newborn lambs aged 2–90 days. The O2 respiratory response was tested by progressive isocarbic hypoxia while minute ventilation (VE), tidal volume (VT), respiratory frequency (f), mean inspiratory flow (VT/TI), were measured. The occlusion pressure (P0.1) was also determined as an index of the neuromuscular output of the drive to breathe. The strength of the peripheral chemoreceptors was evaluated by the transient O2 100% inhalation test and by the early change in VE (delta VE) to cyanide (KCN) infusion. In all of the 2-, 10-, 30-, and 90-day groups of lambs, hypoxia induced a significant increase in P0.1 and in delta VE, delta VT, f, and VT/TI. The 2-day-old lambs showed a significantly lower response to hypoxia than did the older groups. Similarly, during the hyperoxia test and KCN infusion. Delta VE was smaller in the 2-day lambs than in the other lambs. We conclude that the postnatal maturation of the ventilatory response to O2 occurs in the first 10 days of life in newborn lambs and it is largely due to an increase in sensitivity of the O2 chemoreceptors.

Influence of exercise and CO2 on breathing pattern of normal man

1979 ◽  
Vol 47 (1) ◽  
pp. 192-196 ◽  
Author(s):  
J. Askanazi ◽  
J. Milic-Emili ◽  
J. R. Broell ◽  
A. I. Hyman ◽  
J. M. Kinney
Keyword(s):  
Tidal Volume ◽  
Duty Cycle ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Inspiratory Flow ◽  
Breathing Frequency ◽  
Inspiratory Time ◽  
Noninvasive Measurements ◽  
Normal Man

Ventilatory patterns during rest, CO2 inhalation (2, 3, and 4%) and three levels of exercise were analyzed in supine men using a canopy system for noninvasive measurements. Changes in tidal volume (VT) and breathing frequency (f) with equal increases in minute ventilation (VE) differed significantly during exercise and CO2 inhalation. Increases in VE during exercise was accompanied by increases in VT and f. During CO2 inhalation, the change in frequency was less than during exercise. However, when analyzed in terms of inspiratory flow (VT/TI) and inspiratory duty cycle (TI/Ttot), the response to both stimuli was similar. With increases to twice control VE both TI/Ttot and VT/VI increased. Thereafter only VTTI increased with increasing VE. At rest, inspiratory time on a breath by breath basis increased minimally with VT, while changes in inspiratory flow accounted for the variability in VT. These two respiratory stimulants appear to increase ventilation through different mechanisms when analyzed in terms of VT and f. However, changes in inspiratory flow and duty cycle are similar in both.

Respiration in awake cats: sympathectomy and deafferentation of carotid bifurcations

1987 ◽  
Vol 62 (3) ◽  
pp. 932-940 ◽  
Author(s):  
P. C. Szlyk ◽  
D. B. Jennings
Keyword(s):  
Carotid Sinus ◽  
Minute Ventilation ◽  
Reflex Modulation ◽  
Carotid Sinus Nerve ◽  
Inspiratory Time ◽  
Nerve Section ◽  
Arterial Pco2 ◽  
Bilateral Carotid ◽  
Arterial Po2 ◽  
Awake Cats

Respiratory effects of sympathectomy of the carotid bifurcations and, in a subsequent experiment, bilateral carotid sinus nerve section were examined in six awake resting cats. In each intact and denervated state, sequential breaths were analyzed at 10-min intervals up to 80 min. Individual breath frequency (f), tidal volume (VT), and ventilation (V = f X VT) were determined. In individual cats, sympathectomy or deafferentation could cause significant increases or decreases in ventilation or no change. Thus the range of spontaneous variability in breath V as well as minute ventilation (VE), averaged for the group, were not consistently altered in the same direction by either sympathectomy or deafferentation of the carotid bifurcations. Interestingly, in most cats after both sympathectomy (5 of 6) and deafferentation (4 of 6), VT increased and f decreased relative to V. Despite this, after sinus nerve section in two cats arterial PO2 decreased and arterial PCO2 tended to increase relative to VE, suggesting possible effects of deafferentation on ventilation-perfusion balance. Sympathectomy also affected timing such that inspiratory time began to exceed 0.5 of the breath duration at a lower breath f; this effect of sympathectomy was reversed to intact values by subsequent sinus deafferentation. Thus, in eupneic awake cats, sympathetics normally suppress reflex modulation of central timing from carotid chemoreceptors and/or baroreceptors.

Response to Acute Hypercapnia in the Parents of Victims of Sudden Infant Death Syndrome

PEDIATRICS ◽  
1984 ◽  
Vol 73 (5) ◽  
pp. 652-655
Author(s):  
Jonathan M. Couriel ◽  
Anthony Olinsky
Keyword(s):  
Tidal Volume ◽  
Sudden Infant Death Syndrome ◽  
Infant Death ◽  
Cycle Time ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Sudden Infant Death ◽  
Respiratory Cycle ◽  
Sudden Infant ◽  
Inspiratory Time

The ventilatory response to acute hypercapnia was studied in 68 parents of victims of sudden infant death syndrome and 56 control subjects. Tidal volume, inspiratory time, and total respiratory cycle time were measured before and immediately after a vital capacity breath of 13% CO2 in oxygen. Instantaneous minute ventilation, mean inspiratory flow (tidal volume/inspiratory time), and respiratory timing (inspiratory time/total respiratory cycle time) were calculated. Both groups of subjects showed a marked increase in tidal volume (48.4% ± 26.5%), instantaneous minute ventilation (56% ± 35%), and tidal volume/inspiratory time (56.8% ± 33.5%) after inhalation of the test gas, with little change in inspiratory time/total respiratory cycle time. There were no significant differences between the two groups for ventilation before or after inhalation of the test gas. The ventilatory response to acute hypercapnia is mediated by the peripheral chemoreceptors. These results suggest that an inherited abnormality of peripheral chemoreceptor function is unlikely to be a factor leading to sudden infant death syndrome.

scholarly journals Deep-breath frequency in bronchoconstricted monkeys (Macaca fascicularis)

2006 ◽  
Vol 100 (3) ◽  
pp. 786-791 ◽  
Author(s):  
Joseph M. Dybas ◽  
Catharine J. Andresen ◽  
Edward S. Schelegle ◽  
Ryan W. McCue ◽  
Natasha N. Callender ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Respiratory Rate ◽  
Macaca Fascicularis ◽  
Minute Ventilation ◽  
Mechanical Resistance ◽  
External Resistance ◽  
Deep Breath ◽  
Ventilatory Parameters ◽  
Tissue Compliance ◽  
Airway Opening

Deep-breath frequency has been shown to increase in spontaneously obstructed asthmatic subjects. Furthermore, deep breaths are known to be regulated by lung rapidly adapting receptors, yet the mechanism by which these receptors are stimulated is unclear. This study tested the hypothesis that deep-breath frequency increases during experimentally induced bronchoconstriction, and the magnitude of the increased deep-breath frequency is dependent on the method by which bronchoconstriction is induced. Nine cynomolgus monkeys ( Macaca fascicularis) were challenged with methacholine (MCh), Ascaris suum (AS), histamine, or an external mechanical resistance. Baseline (BL) and challenge deep-breath frequency were calculated from the number of deep breaths per trial period. Airway resistance (Raw) and tissue compliance (Cti), as well as tidal volume, respiratory rate, and minute ventilation, were analyzed for BL and challenged conditions. Transfer impedance measurements were fit with the DuBois model to determine the respiratory parameters (Raw and Cti). The flow at the airway opening was measured and analyzed on a breath-by-breath basis to obtain the ventilatory parameters (tidal volume, respiratory rate, and minute ventilation). Deep-breath frequency resulting from AS and histamine challenges [0.370 (SD 0.186) and 0.467 breaths/min (SD 0.216), respectively] was significantly increased compared with BL, MCh, or external resistance challenges [0.61 (SD 0.046), 0.156 (SD 0.173), and 0.117 breaths/min (SD 0.082), respectively]. MCh and external resistance challenges resulted in insignificant changes in deep-breath frequency compared with BL. All four modalities produced similar levels of bronchoconstriction, as assessed through changes in Raw and Cti, and had similar effects on the ventilatory parameters except that non-deep-breath tidal volume was decreased in AS and histamine. We propose that increased deep-breath frequency during AS and histamine challenge is the result of increased vascular permeability, which acts to increase rapidly adapting receptor activity.

Augmentation of CO2 drives by chlormadinone acetate, a synthetic progesterone

1984 ◽  
Vol 56 (6) ◽  
pp. 1627-1632 ◽  
Author(s):  
H. Kimura ◽  
F. Hayashi ◽  
A. Yoshida ◽  
S. Watanabe ◽  
I. Hashizume ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Inspiratory Flow ◽  
Pressure Response ◽  
Respiratory Drive ◽  
Occlusion Pressure ◽  
Physiological Basis ◽  
Load Compensation ◽  
Chlormadinone Acetate ◽  
Arterial Blood ◽  
Resistive Loading

We studied 10 male subjects who were administered chlormadinone acetate (CMA), a potent synthetic progesterone, to clarify the physiological basis of its respiratory effects. Arterial blood gas tension, resting ventilation, and respiratory drive assessed by ventilatory and occlusion pressure response to CO2 with and without inspiratory flow-resistive loading were measured before and 4 wk after CMA administration. In all subjects, arterial PCO2 decreased significantly by 5.7 +/- 0.6 (SE) Torr with an increase in minute ventilation by 1.8 +/- 0.6 l X min-1, whereas no significant changes were seen in O2 uptake. During unloaded conditions, both slopes of occlusion pressure and ventilatory response to CO2 increased, being statistically significant in the former but showing nonsignificant trends in the latter. Furthermore, inspiratory flow-resistive loading (16 cmH2O X l(-1) X s) increased both slopes more markedly after CMA. The magnitudes of load compensation, assessed by the ratio of loaded to unloaded slope of the occlusion pressure response curve, were increased significantly. We concluded CMA is a potent respiratory stimulant that increases the CO2 chemosensitivity and neuromechanical drives in the load-compensation mechanism.

Ventilatory effects and interactions with change in PaO2 in awake goats

1991 ◽  
Vol 71 (4) ◽  
pp. 1254-1260 ◽  
Author(s):  
L. Daristotle ◽  
M. J. Engwall ◽  
W. Z. Niu ◽  
G. E. Bisgard
Keyword(s):  
Tidal Volume ◽  
Carotid Body ◽  
Ventilatory Response ◽  
Respiratory Frequency ◽  
Systemic Hypoxia ◽  
Ventilatory Effects ◽  
Arterial Po2

We utilized selective carotid body (CB) perfusion while changing inspired O2 fraction in arterial isocapnia to characterize the non-CB chemoreceptor ventilatory response to changes in arterial PO2 (PaO2) in awake goats and to define the effect of varying levels of CB PO2 on this response. Systemic hyperoxia (PaO2 greater than 400 Torr) significantly increased inspired ventilation (VI) and tidal volume (VT) in goats during CB normoxia, and systemic hypoxia (PaO2 = 29 Torr) significantly increased VI and respiratory frequency in these goats. CB hypoxia (CB PO2 = 34 Torr) in systemic normoxia significantly increased VI, VT, and VT/TI; the ventilatory effects of CB hypoxia were not significantly altered by varying systemic PaO2. We conclude that ventilation is stimulated by systemic hypoxia and hyperoxia in CB normoxia and that this ventilatory response to changes in systemic O2 affects the CB O2 response in an additive manner.

Effect of respiratory apparatus on respiration

1984 ◽  
Vol 57 (2) ◽  
pp. 475-480 ◽  
Author(s):  
C. Weissman ◽  
J. Askanazi ◽  
J. Milic-Emili ◽  
J. M. Kinney
Keyword(s):  
Tidal Volume ◽  
Duty Cycle ◽  
Breathing Pattern ◽  
Minute Ventilation ◽  
Inspiratory Flow ◽  
Percentage Increase ◽  
Breathing Patterns ◽  
Normal Volunteers ◽  
Abdominal Operation ◽  
Respiratory Apparatus

A mouthpiece plus noseclip (MP & NC) is frequently used in performing measurements of breathing patterns. Although the effects the apparatus exerts on breathing patterns have been studied, the mechanism of the changes it causes remains unclear. The current study examines the effects on respiratory patterns of a standard (17-mm-diam) MP & NC during room air (RA) breathing and the administration of 2 and 4% CO2 in normal volunteers and in patients 2–4 days after abdominal operation. When compared with values obtained with a noninvasive canopy system, the MP & NC induced increases in minute ventilation (VE), tidal volume (VT), and mean inspiratory flow (VT/TI), but not frequency (f) or inspiratory duty cycle, during both RA and CO2 administration. The percentage increase in VE, VT, and VT/TI caused by the MP & NC decreased as the concentration of CO2 increased. During RA breathing, the application of noseclip alone resulted in a decrease in f and an increase in VT, but VE and VT/TI were unchanged. The changes were attenuated during the administration of 2 and 4% CO2. Reducing the diameter of the mouthpiece to 9 mm abolished the alterations in breathing pattern observed with the larger (17-mm) diameter MP.

Sign in / Sign up

Export Citation Format

Share Document