Effects of lung deflation induced by tiotropium/olodaterol on the cardiocirculatory responses to exertion in COPD

In five anesthetized paralyzed cats, mechanically ventilated with tidal volumes of 36–48 ml, the isovolume pressure-flow relationships of the lung and respiratory system were studied. The expiratory pressure was altered between 3 and -12 cmH2O for single tidal expirations. Isovolume pressure-flow plots for three lung volumes showed that the resistive pressure-flow relationships were curvilinear in all cases, fitting Rohrer's equation: P = K1V + K2V2, where P is the resistive pressure loss, K1 and K2 are Rohrer's coefficients, and V is flow. Values of K1 and K2 declined with lung inflation, consistent with the volume dependence of pulmonary (RL) and respiratory system resistances (Rrs). During lung deflation against atmospheric pressure, RL and Rrs tended to remain constant through most of expiration, resulting in a nearly linear volume-flow relationship. In the presence of a fixed respiratory system elastance, the shape of the volume-flow profile depended on the balance between the volume and the flow dependence of RL and Rrs. However, the flow dependence of RL and Rrs indicates that their measured values will be affected by all factors that modify expiratory flow, e.g., respiratory system elastance, equipment resistance, and the presence of respiratory muscle activity.

Download Full-text

Effect of hypoxia on reflex responses of tracheal submucosal glands

Journal of Applied Physiology ◽

10.1152/jappl.1995.78.5.1651 ◽

1995 ◽

Vol 78 (5) ◽

pp. 1651-1656 ◽

Cited By ~ 5

Author(s):

R. Hejal ◽

K. P. Strohl ◽

B. Erokwu ◽

N. S. Cherniack ◽

M. A. Haxhiu

Keyword(s):

Right Atrial ◽

Liquid Droplets ◽

Submucosal Gland ◽

Response Curves ◽

Reflex Responses ◽

Hyperoxic Condition ◽

Airway Secretion ◽

Calculated Volume ◽

Lung Deflation ◽

Stimulation Of

The effects of moderate sustained normocapnic hypoxia on tracheal submucosal gland reflex responses were studied. Experiments were performed in anesthetized, paralyzed, and mechanically ventilated dogs. The changes in the number of secreting glands and volume of secreted fluid in the subsequent period of time were recorded after 15–30 min of controlled ventilation with room air [arterial PO2 (PaO2) 86 +/- 3 Torr], hypoxic gas mixture (PaO2 49 +/- 4 Torr), or 100% O2 (PaO2 339 +/- 39 Torr), under isocapnic and isohydric conditions. The hillocks method was used to quantify the changes in submucosal gland secretion. The changes in secretion 30 s after stimulation of pulmonary C-fiber receptors by right atrial injection of capsaicin (10 micrograms/kg; n = 10) were markedly lower during moderate hypoxia than in normoxia or hyperoxia. Differences in the number of liquid droplets and the volume of secreted fluid were statistically significant (P < 0.05 and P < 0.001, respectively). Stimulation of airway rapidly adapting receptors by lung deflation increased airway secretion; the number of “hillocks” and the volume of secreted fluid were lower in hypoxic than in hyperoxic state. Differences between response curves for the number of glands activated and secreted volume were statistically significant (P < 0.05 and P < 0.001). The number of glands activated by substance P given locally by arterial infusion was not affected by the state of oxygenation, but the calculated volume of secreted fluid was lower during the hypoxic state than under hyperoxic condition (P = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Studies on the role of the lung deflation reflex

Respiration Physiology ◽

10.1016/0034-5687(70)90081-2 ◽

1970 ◽

Vol 10 (2) ◽

pp. 172-183 ◽

Cited By ~ 36

Author(s):

E.A. Koller ◽

P. Ferrer

Keyword(s):

Lung Deflation

Download Full-text

The influence of procaine and isoprenaline on the lung deflation reflex during the histamine-induced bronchial asthma attack

Agents and Actions ◽

10.1007/bf01972695 ◽

1975 ◽

Vol 5 (5) ◽

pp. 559-564 ◽

Cited By ~ 2

Author(s):

J. Kohl ◽

E. A. Koller

Keyword(s):

Bronchial Asthma ◽

Asthma Attack ◽

Lung Deflation

Download Full-text

Maturation of respiratory reflex responses in the piglet

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.2.608 ◽

1991 ◽

Vol 70 (2) ◽

pp. 608-616 ◽

Cited By ~ 21

Author(s):

B. Haxhiu-Poskurica ◽

W. A. Carlo ◽

M. J. Miller ◽

J. M. DiFiore ◽

M. A. Haxhiu ◽

...

Keyword(s):

Smooth Muscle ◽

Airway Smooth Muscle ◽

Phrenic Nerve ◽

Muscle Tone ◽

Muscle Tension ◽

Age Groups ◽

Force Transducer ◽

Reflex Responses ◽

C Fiber ◽

Lung Deflation

Stimulation of chemo-, irritant, and pulmonary C-fiber receptors reflexly constricts airway smooth muscle and alters ventilation in mature animals. These reflex responses of airway smooth muscle have, however, not been clearly characterized during early development. In this study we compared the maturation of reflex pathways regulating airway smooth muscle tone and ventilation in anesthetized, paralyzed, and artificially ventilated 2- to 3- and 10-wk-old piglets. Tracheal smooth muscle tension was measured from an open tracheal segment by use of a force transducer, and phrenic nerve activity was measured from a proximal cut end of the phrenic nerve. Inhalation of 7% CO2 caused a transient increase in tracheal tension in both age groups, whereas hypoxia caused no airway smooth muscle response in either group. The phrenic responses to 7% CO2 and 12% O2 were comparable in both age groups. Lung deflation and capsaicin (20 micrograms/kg iv) administration did not alter tracheal tension in the younger piglets but caused tracheal tension to increase by 87 +/- 28 and 31 +/- 10%, respectively, in the older animals (both P less than 0.05). In contrast, phrenic response to both stimuli was comparable between ages: deflation increased phrenic activity while capsaicin induced neural apnea. Laryngeal stimulation did not increase tracheal tension but induced neural apnea in both age groups. These data demonstrate that between 2 and 10 wk of life, piglets exhibit developmental changes in the reflex responses of airway smooth muscle situated in the larger airways in response to irritant and C-fiber but not chemoreceptor stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Could Pharmacologic Lung Deflation Modify Cardiac Structural and Functional Alterations?

American Journal of Respiratory and Critical Care Medicine ◽

10.1164/rccm.201512-2417le ◽

2016 ◽

Vol 193 (8) ◽

pp. 932-932

Author(s):

Goktug Savas ◽

Nihat Kalay ◽

Inci Gulmez

Keyword(s):

Lung Deflation

Download Full-text

Effects of tonic vagal input on breathing pattern in newborn rabbits

Journal of Applied Physiology ◽

10.1152/jappl.1985.59.1.223 ◽

1985 ◽

Vol 59 (1) ◽

pp. 223-228 ◽

Cited By ~ 12

Author(s):

T. Trippenbach ◽

G. Kelly ◽

D. Marlot

Keyword(s):

Breathing Pattern ◽

Minute Ventilation ◽

Vagal Activity ◽

Respiratory Effects ◽

Tracheal Pressure ◽

Negative Pressure Breathing ◽

Lung Deflation ◽

Reflex Stimulation ◽

Cardiac Receptors ◽

Respiratory Reflex

Respiratory effects of positive and negative pressure breathing were studied in 1- and 4-day-old rabbit pups anesthetized with ketamine (50 mg/kg, im) and acepromazine (3 mg/kg, im). We recorded tidal volume (VT), tracheal pressure (Ptr), and integrated diaphragmatic EMG (DiEMG). Inspiratory (TI) and expiratory time (TE) were measured from the records of DiEMG. During breathing with increased Ptr by 1 or 2 cmH2O, VT, minute ventilation (VE), and respiratory rate (f) decreased. Changes in f relied on a TE prolongation. Neither DiEMG nor its rate of rise (DiEMGt) were affected. Except for VT decrease during positive Ptr, all other effects disappeared after vagotomy. Our results indicate that an increase in tonic vagal activity interacts with the mechanisms controlling TE and has no effect on depth and duration of inspiration. When Ptr decreased by 1 and 2 cmH2O, VE increased due to an increase in f. Increase in f relied on shortening of both TI and TE; the TE effect being more pronounced. DiEMG and DiEMGt also increased. Adverse effects of lung deflation and vagotomy strongly suggest that the respiratory reflex stimulation due to decrease in Ptr does not rely on inhibition of the slowly adapting stretch receptor activity. Therefore other excitatory vagal inputs must be responsible for this response. We propose two vagally mediated inputs: the irritant and/or the cardiac receptors.

Download Full-text

Effects of methacholine and hypocapnia on airways and collateral ventilation in dogs

Journal of Applied Physiology ◽

10.1152/jappl.1979.46.5.966 ◽

1979 ◽

Vol 46 (5) ◽

pp. 966-972 ◽

Cited By ~ 20

Author(s):

L. J. Smith ◽

C. R. Inners ◽

P. B. Terry ◽

H. A. Menkes ◽

R. J. Traystman

Keyword(s):

Time Constant ◽

Fiber Optic ◽

Small Airways ◽

Before And After ◽

Airways Resistance ◽

Lung Deflation ◽

Collateral Ventilation

We studied the effects of hypocapnia and methacholine on small airways resistance (Rsaw) and collateral ventilation in anesthetized paralyzed dogs. The animals were ventilated with air while either 10% CO2 or air (hypocapnia) was infused through a segment obstructed with a fiber-optic bronchoscope. Measurements were made before and after instillation of methacholine into the obstructed segment. Collateral resistance (Rcoll) and Rsaw increased with hypocapnia and methacholine. The time constant for collateral ventilation increased with hypocapnia, but did not change with methacholine because of decreases in the compliance of the obstructed segment. We conclude that collateral channels respond to methacholine and hypocapnia in a manner similar to small airways and that local parasympathomimetic stimulation, unlike lung deflation does not increase the time constant for collateral ventilation.

Download Full-text