scholarly journals The Interrelationship Between Pulmonary Mechanics and the Spontaneous Breathing Pattern in the Tokay Lizard, Gekko Gecko

1984 ◽  
Vol 113 (1) ◽  
pp. 203-214 ◽  
Author(s):  
WILLIAM K. MILSOM
Keyword(s):  
Tidal Volume ◽  
Spontaneous Breathing ◽  
Breathing Pattern ◽  
Pulmonary Ventilation ◽  
Periodic Breathing ◽  
Breath Holding ◽  
Pulmonary Mechanics ◽  
Respiratory Drive ◽  
Breathing Patterns ◽  
Gekko Gecko

The normal breathing pattern of the Tokay gecko (Gekko gecko) consists of single breaths or bursts of a few breaths separated by periods of breath holding. Increases in pulmonary ventilation that accompany rises in body temperature are caused by increases in respiratory frequency due to shortening of the periods of breath holding. Tidal volume and breath duration remain relatively constant. Measurements of the mechanical work associated with spontaneous breathing yielded values that were similar to those calculated for breaths of the same size and duration based on work curves generated during pump ventilation of anaesthetized animals. In this species, the pattern of periodic breathing and the ventilatory responses to changes in respiratory drive correspond with predictions of optimal breathing patterns based on calculations of the mechanical cost of ventilation. Bilateral vagotomy drastically alters the breathing pattern producing an elevation in tidal volume, a slowing of breathing frequency, and a prolongation of the breath duration. These alterations greatly increase the mechanical cost of ventilation. These data suggest that periodic breathing in this species may represent an adaptive strategy which is under vagal afferent control and which serves to minimize the cost of breathing.

scholarly journals Mechanical Analysis of Spontaneous Breathing in the Semi-Aquatic Turtle, Pseudemys Scripta

1986 ◽  
Vol 125 (1) ◽  
pp. 157-171 ◽  
Author(s):  
Timothy Z. Vitalis ◽  
William K. Milsom
Keyword(s):  
Tidal Volume ◽  
Breathing Pattern ◽  
Work Of Breathing ◽  
Pulmonary Ventilation ◽  
Periodic Breathing ◽  
Adaptive Strategy ◽  
Breath Holding ◽  
Breath Hold ◽  
Breathing Frequency ◽  
Pseudemys Scripta

The normal breathing pattern of Pseudemys scripta (Schoepff) consists of a continuous burst of breaths separated by a variable period of breath holding. Under normoxic conditions, tidal volume was 6.9 ml kg−1 and the number of breaths was 1.9 min−1. Increases in pulmonary ventilation upon stimulation by hypercapnia (3% CO2) or hypoxia (4% O2) are caused primarily by increases in the number of breaths per minute due to a shortening of the breath-hold period. Tidal volume and breath duration remain unchanged. The instantaneous breathing frequency (f' = 60/Ttot) of 35 ± 2min−1 corresponds to continuous pump frequencies that minimize the rate of the mechanical work of breathing in anaesthetized turtles. This indicates that turtles breathe at a combination of tidal volume and f' that minimizes the power required to ventilate the lungs. To increase ventilation, the breath hold is shortened and more breaths are taken at this optimal combination. Bilateral vagotomy drastically alters the breathing pattern, producing an elevation in tidal volume, a slowing of breathing frequency, and a prolongation of breath duration while total ventilation remains unchanged. These data suggest that periodic breathing in this species may represent an adaptive strategy which is under vagal control and which serves to minimize the cost of breathing.

Estimation of cardiorespiratory transfer under spontaneous breathing conditions: a theoretical study

1997 ◽  
Vol 273 (2) ◽  
pp. H1012-H1023 ◽  
Author(s):  
T. S. Kim ◽  
M. C. Khoo
Keyword(s):  
Spontaneous Breathing ◽  
Breathing Pattern ◽  
Theoretical Study ◽  
Simulated Data ◽  
Periodic Breathing ◽  
Breathing Patterns ◽  
Tidal Breathing ◽  
Sinus Arrhythmia ◽  
Ventilatory Pattern ◽  
Data Length

Using simulated noisy sequences of respiration and heart rate, we assessed the accuracy of the respiratory sinus arrhythmia transfer function (RSATF) estimation under three kinds of spontaneous breathing patterns: regular or tidal breathing, periodic breathing with apnea, and broadband breathing. Estimation employing the cross-power and autopower spectra of the simulated data produced RSATF estimates that were generally more variable than those computed with an autoregressive modeling approach. Variability and bias errors in the RSATF estimates became larger as respiratory bandwidth decreased when the breathing pattern changed from broadband to periodic to regular breathing. However, between frequencies of 0.1 and 0.3 Hz, these errors fell within 12% in all breathing patterns. Error in the RSATF estimates was only slightly increased, with reductions in data length to as low as 90 s. The results suggest the feasibility of obtaining accurate estimates of RSATF between 0.1 and 0.8 Hz from a wide variety of conditions, such as in different sleep-wake states where voluntary control of breathing is not possible and the ventilatory pattern may vary substantially.

Control of breathing patterns and abdominal muscles during graded loads and tilt

1994 ◽  
Vol 76 (6) ◽  
pp. 2473-2480 ◽  
Author(s):  
J. Barrett ◽  
F. Cerny ◽  
J. A. Hirsch ◽  
B. Bishop
Keyword(s):  
Tidal Volume ◽  
Breathing Pattern ◽  
Body Position ◽  
Central Pattern Generators ◽  
Abdominal Muscles ◽  
Respiratory Drive ◽  
Breathing Patterns ◽  
Inspiratory Capacity ◽  
Pattern Generators ◽  
End Tidal

Tilting from supine to upright purportedly enhances both segmental and pulmonary proprioceptive feedback, whereas an expiratory threshold load (ETL) preferentially enhances pulmonary feedback. To test this we studied 13 adults when supine and 60 degrees and 90 degrees head up. We measured tidal volume, inspiratory duration (TI), and expiratory duration (TE) from flow; estimated end-expiratory lung volume from inspiratory capacity; and determined burst amplitudes and durations from abdominal electromyograms (EMGs). ETLs were incremented from 0 (control) to 25 cmH2O in 5-cmH2O steps. Tidal volume was significantly increased by ETL but was unaffected by body position. Every load prolonged TE, whereas TI remained unchanged. When subjects were supine, abdominal EMGs were silent but became tonically active when subjects were upright. During ETL, abdominal activity became rhythmical and phase locked to expiration. Bursts amplitudes were enhanced with each increment in ETL, but burst durations did not change even though TE was prolonged. The altered breathing pattern and active expiration augmented inspiratory flow and decreased end-tidal PCO2. Responses were greatest when subjects were 90 degrees head up. The load-related increments in abdominal recruitment, with no change in burst durations, fit the concept of two central pattern generators: one controlling pattern and the other controlling rhythm of the central respiratory drive.

Normoxic and hypoxic breathing pattern in newborn grey seals

1989 ◽  
Vol 67 (2) ◽  
pp. 483-487 ◽  
Author(s):  
Jacopo P. Mortola ◽  
Clement Lanthier
Keyword(s):  
Tidal Volume ◽  
Breathing Pattern ◽  
Halichoerus Grypus ◽  
Breathing Rate ◽  
Allometric Relationships ◽  
Breathing Patterns ◽  
Hypoxic Conditions ◽  
Regulation Of Breathing ◽  
Expiratory Flow

We studied the breathing patterns of three newborn grey seals (Halichoerus grypus) at 2 – 3 days of age under normoxic and hypoxic conditions with the barometric technique, which does not require the animal to be restrained. Normoxic tidal volume was deeper and breathing rate slower than expected for newborns of this size on the basis of previously published allometric relationships. In addition, two characteristics were readily apparent: (i) occasional sudden long apneas, often exceeding 30 s in duration, and (ii) consistent brief interruptions of expiratory flow. Neither aspect is common in terrestrial newborns of this age, but both have been previously observed in adult seals. During hypoxia (10 min of 15% O2 and 10 min of 10% O2), ventilation increased markedly and steadily, at variance with what occurs in newborns of other species, indicating a precocial development of the regulation of breathing. This latter result also suggests that the blunted response to hypoxia previously reported in adult seals may be acquired postnatally with diving experience.

scholarly journals Hypoxia-induced vagal withdrawal is independent of the hypoxic ventilatory response in men

2019 ◽  
Vol 126 (1) ◽  
pp. 124-131 ◽  
Author(s):  
Christoph Siebenmann ◽  
Camilla K. Ryrsø ◽  
Laura Oberholzer ◽  
James P. Fisher ◽  
Linda M. Hilsted ◽  
...  
Keyword(s):  
Heart Rate ◽  
Tidal Volume ◽  
Respiratory Rate ◽  
Spontaneous Breathing ◽  
Animal Studies ◽  
Pulmonary Ventilation ◽  
Vagal Activity ◽  
Adrenergic Blockade ◽  
Controlled Breathing ◽  
Vagal Withdrawal

Hypoxia increases heart rate (HR) in humans by sympathetic activation and vagal withdrawal. However, in anaesthetized dogs hypoxia increases vagal activity and reduces HR if pulmonary ventilation does not increase and we evaluated whether that observation applies to awake humans. Ten healthy males were exposed to 15 min of normoxia and hypoxia (10.5% O2), while respiratory rate and tidal volume were volitionally controlled at values identified during spontaneous breathing in hypoxia. End-tidal CO2 tension was clamped at 40 mmHg by CO2 supplementation. β-Adrenergic blockade by intravenous propranolol isolated vagal regulation of HR. During spontaneous breathing, hypoxia increased ventilation by 3.2 ± 2.1 l/min ( P = 0.0033) and HR by 8.9 ± 5.5 beats/min ( P < 0.001). During controlled breathing, respiratory rate (16.3 ± 3.2 vs. 16.4 ± 3.3 breaths/min) and tidal volume (1.05 ± 0.27 vs. 1.06 ± 0.24 l) were similar for normoxia and hypoxia, whereas the HR increase in hypoxia persisted without (8.6 ± 10.2 beats/min) and with (6.6 ± 5.6 beats/min) propranolol. Neither controlled breathing ( P = 0.80), propranolol ( P = 0.64), nor their combination ( P = 0.89) affected the HR increase in hypoxia. Arterial pressure was unaffected ( P = 0.48) by hypoxia across conditions. The hypoxia-induced increase in HR during controlled breathing and β-adrenergic blockade indicates that hypoxia reduces vagal activity in humans even when ventilation does not increase. Vagal withdrawal in hypoxia seems to be governed by the arterial chemoreflex rather than a pulmonary inflation reflex in humans. NEW & NOTEWORTHY Hypoxia accelerates the heart rate of humans by increasing sympathetic activity and reducing vagal activity. Animal studies have indicated that hypoxia-induced vagal withdrawal is governed by a pulmonary inflation reflex that is activated by the increased pulmonary ventilation in hypoxia. The present findings, however, indicate that humans experience vagal withdrawal in hypoxia even if ventilation does not increase, indicating that vagal withdrawal is governed by the arterial chemoreflex rather than a pulmonary inflation reflex.

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.

scholarly journals Pulmonary Mechanics and the Work of Breathing in the Lizard, Gekko Gecko

1984 ◽  
Vol 113 (1) ◽  
pp. 187-202 ◽  
Author(s):  
WILLIAM K. MILSOM ◽  
TIMOTHY Z. VITALIS
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Body Cavity ◽  
The Body ◽  
Pulmonary Mechanics ◽  
Lung Inflation ◽  
Gekko Gecko ◽  
Tokay Gecko

Measurements of pulmonary mechanics made on anaesthetized specimens of the Tokay gecko Gekkogecko (Linné), indicate that both static and dynamic pulmonary mechanics are dominated by the mechanics of the body cavity and chest wall. The lungs are relatively large and compliant and offer little resistance to air flow at any of the ventilation frequencies (f) used in this study. The body wall is relatively stiff and becomes less compliant with increasing ventilation frequency and with increasing tidal volume (VT) at the higher frequencies. The vast majority of the work performed in breathing is used to overcome elastic forces in the chest wall resisting lung inflation. This work increases exponentially with increases in volume. As a consequence, in terms of total ventilation, the most economic breathing pattern is a high frequency, low tidal volume pattern in which changes in minute ventilation (VE) are most economically produced solely by changes in f. Because reductions in tidal volume drastically reduce alveolar ventilation volume while dead space remains constant, the same arguments do not apply to alveolar minute ventilation (VA). In terms of alveolar minute ventilation, there is an optimum combination of f and VT for each level of VA, with changes in VA being most economically produced by almost equal changes in both f and VT

Effect of breathing pattern on gas mixing in a model with asymmetrical alveolar ducts

1985 ◽  
Vol 58 (1) ◽  
pp. 18-26 ◽  
Author(s):  
C. L. Bowes ◽  
J. D. Richardson ◽  
G. Cumming ◽  
K. Horsfield
Keyword(s):  
Breathing Pattern ◽  
Breath Holding ◽  
Gas Mixing ◽  
Breathing Patterns ◽  
Discrete Elements ◽  
Finite Difference Technique ◽  
Single Breath ◽  
Pulmonary Airways ◽  
Conducting Airways ◽  
And Diffusion

A model of the pulmonary airways was used to study three single-breath indices of gas mixing, dead space (VD), slope of the alveolar plateau, and alveolar mixing inefficiency (AMI). In the model, discrete elements of airway volume were represented by nodes. Using a finite difference technique the differential equation for simultaneous convection and diffusion was solved for the nodal network. Conducting airways and respiratory bronchioles were modeled symmetrically, but alveolar ducts asymmetrically, permitting interaction between convection and diffusion. VD, alveolar slope, and AMI increased with increasing flow. Similar trends were seen with inspired volume, although slope decreased at high inspired volumes with constant flow. VD was affected most by inspiratory flow and AMI and alveolar slope by expiratory time. VD fell approximately exponentially with time of breath holding. Eight different breathing patterns were compared. They had a small effect on alveolar slope and AMI and a greater effect on VD. The model shows how series and parallel inhomogeneity occur together and interact in asymmetrical systems: the old argument as to which is the more important should be abandoned.

Coordination of swallowing and respiration in unconscious subjects

1991 ◽  
Vol 70 (3) ◽  
pp. 988-993 ◽  
Author(s):  
T. Nishino ◽  
K. Hiraga
Keyword(s):  
General Anesthesia ◽  
Tidal Volume ◽  
Endotracheal Tube ◽  
Breathing Pattern ◽  
Recovery Period ◽  
Respiratory Frequency ◽  
Breathing Patterns ◽  
Expiratory Phase ◽  
Unconscious Patients

We investigated the coordination of swallowing and breathing in 11 unconscious patients with an endotracheal tube in place during the recovery period from general anesthesia. Swallows occurred during both the inspiratory and expiratory phases with no preponderant occurrence during either phase. When a swallow occurred during inspiration, the inspiration was interrupted immediately and was followed by expiration, but the durations of both inspiration and expiration were progressively increased as the time from the onset of inspiration to the onset of swallowing was progressively delayed. A swallow coinciding with the expiratory phase progressively prolonged the duration of the expiration that had been interrupted as the timing of swallowing was progressively delayed. Repeated swallows invariably and in a predictable manner caused changes in the breathing pattern. Thus when the frequency of regularly repeated swallows was relatively high, the breathing pattern was characterized by regular, shallow, and rapid breaths. When the frequency of regularly repeated swallows was relatively low, the breathing pattern was characterized by regular, deep, and slow breaths. When the frequency of repeated swallows was irregular, the breathing patterns were characterized by inconsistent changes in tidal volume and respiratory frequency. Our results indicate that, in unconscious subjects, some mechanisms integrating respiration and swallowing are operative and responsible for changes in breathing patterns during swallowing.

The Effect of Temperature and Hypoxia Hypercapnia on the Respiratory Pattern of the Unrestrained Lizard, Pogona Vitticeps

1995 ◽  
Vol 43 (2) ◽  
pp. 165 ◽  
Author(s):  
S Crafter ◽  
MI Soldini ◽  
CB Daniels ◽  
AW Smits
Keyword(s):  
Tidal Volume ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Average Frequency ◽  
Respiratory Pattern ◽  
Effect Of Temperature ◽  
Breath Holding ◽  
Breathing Patterns ◽  
Pogona Vitticeps ◽  
Lower Temperature

The effect of altering body temperature and the oxygen and carbon dioxide composition of inspired air on the respiratory pattern of the unrestrained lizard Pogona vitticeps was determined using pneumotachometry that did not require restraining the animal. P. vitticeps demonstrated a typical reptilian breathing pattern of groups of breaths separated by periods of breath-holding. Respiratory patterns were measured at 18 degrees C and at 37 degrees C. Minute ventilation decreased at the lower temperature as a result of a decrease in average frequency. Tidal volume was temperature independent. The change in average frequency resulted from both a decrease in the instantaneous inspiratory time and an increase in the time spent in a non-ventilatory period. As a result, the work of breathing was less at 18 degrees C than at 37 degrees C. With the exception of tidal volume, breathing patterns were independent of changes to the composition of inspired air. At both 18 degrees C and 37 degrees C, inspiring a 5% CO2/13% O-2/82% N-2 gas mixture increased tidal volume but did not increase minute ventilation.

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