Pulmonary to arterial circulatory transfer function: importance in respiratory control.

Lange, Ramon L.; Horgan, James D.; Botticelli, James T.; Tsagaris, Theofilos J.; Carlisle, R; Kuida, Hiroshi

doi:10.1152/jappl.1966.21.4.1281

Cited by 42 publications

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“…This disturbance (P a O 2 ) is filtered as it passes through the heart and associated vasculature and is further delayed by p seconds in transit to the carotid bodies. Denoting the filtered and delayed stimulus that arrives at the carotid bodies as P a O 2 p , we can write (29) P a O 2 p ͑s͒ ϭ P a O 2 ͑s͒ e Ϫ ps ͑1 ϩ 1 s͒͑1 ϩ 2 s͒ (A2) where 1 and 2 are filtering time constants and p is circulation delay (lung to carotid body). This disturbance in partial pressure stimulates the carotid bodies to produce a change in ventilation V P. In previous work, our laboratory has shown that the lamb, unlike the human, has a negligible brisk response to hypercapnia (50), suggesting that the usual multiplicative effect of hypoxia on the carotid body response to Pa CO 2 is absent under the conditions of our experiments, and as a result the exponential response to hypoxia (the peripheral controller response) can be adequately modeled as…”

Section: Appendixmentioning

confidence: 99%

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

Wilkinson¹,

Sia²,

Skuza³

et al. 2005

Journal of Applied Physiology

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. Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb. J Appl Physiol 98: 437-446, 2005. First published October 8, 2004 doi:10.1152/japplphysiol.00532.2004We examined the effect of hypoxia and hypercapnia administered during deliberately induced periodic breathing (PB) in seven lambs following posthyperventilation apnea. Based on our theoretical analysis, the sensitivity or loop gain (LG) of the respiratory control system of the lamb is directly proportional to the difference between alveolar PO2 and inspired PO2. This analysis indicates that during PB, when by necessity LG is Ͼ1, replacement of the inspired gas with one of reduced PO2 lowers LG; if we made inspired PO2 approximate alveolar PO2, we predict that LG would be approximately zero and breathing would promptly stabilize. In six lambs, we switched the inspired gas from an inspiratory oxygen fraction of 0.4 to one of 0.12 during an epoch of PB; PB was immediately suppressed, supporting the view that the peripheral chemoreceptors play a pivotal role in the genesis and control of unstable breathing in the lamb. In the six lambs in which we administered hypercapnic gas during PB, breathing instability was also suppressed, but only after a considerable time lag, indicating the CO2 effect is likely to have been mediated through the central chemoreceptors. When we simulated both interventions in a published model of the adult respiratory controller, PB was immediately suppressed by CO2 inhalation and exacerbated by inhalation of hypoxic gas. These fundamentally different responses in lambs and adult humans demonstrate that PB has differing underlying mechanisms in the two species.Cheyne-Stokes respiration; hypoxia; hypercapnia; sleep apnea syndromes; control of breathing; periodic breathing PERIODIC BREATHING (PB), or Cheyne-Stokes respiration, appears under a wide range of physiological and clinical conditions. It is particularly prevalent during sleep, occurring at sea level in apparently normal-term and preterm infants (22,43), at high altitude in normal adults (27), and after hypoxic exposure in experimental animals (11,21). It also occurs in patients with congestive heart failure (36), with idiopathic central sleep apnea (52), with bilateral brain stem lesions (40), and in periodic obstructive sleep apnea (41). A form of PB can also be found in hibernating animals (7,34).Although it is often assumed that the underlying mechanisms causing PB in infants and adults are similar, in each case involving instability of the chemical control system that regulates breathing, there are some marked differences in the pattern of PB and its responses to changes in inspired gas that remain largely unexplained. For example, in preterm infants, the waxing and waning pattern of PB that is characteristic of the adult is replaced by a more or less abrupt on-off pattern that shows little change in tidal volume during the breathing phase (42); this pattern resembles that seen in hibernating animals (34). Furthermore, although the re...

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Section: Appendixmentioning

confidence: 99%

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

Wilkinson¹,

Sia²,

Skuza³

et al. 2005

Journal of Applied Physiology

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“…There are absolute lag times, representing the time taken for blood to flow between effectors, that are dependent on blood volume and cardiac output, and there are arterial and venous mixing processes that 'smear' the blood gas waveform, and depend on the effective mixing volume and cardiac output. In humans, the arterial effective mixed blood volume (Va mix ) is approximately 10-15% of arterial blood volume (calculated from data published by Lange et al, 1966). To my knowledge, comparable data are not available for pinnipeds.…”

Section: Cardiovascular Responsesmentioning

confidence: 99%

“…Lung volume (VL) could differ between surface respiration and apnoea onset. The respiratory exchange ratio (RER) was calculated as: Blix et al, 1983;Castellini et al, 1992;Cunningham et al, 1986;Davis and Kanatous, 1999;Duffin et al, 2000;Elsner et al, 1970;Fortune et al, 1992;Kooyman and Campbell, 1972;Kooyman et al, 1971Kooyman et al, , 1973Kooyman et al, , 1980Lange et al, 1966;Ponganis et al, 1993;Zapol et al, 1979. …”

Section: Gas Exchangementioning

confidence: 99%

“…The arterial and venous transfer functions were each modeled as the sum of two components, a circulatory lag time and a mixing function (Lange et al, 1966). Circulatory lag times were assumed to be proportional to cardiac output and blood volume, and the latter was divided into arterial blood (Vb a ) and venous blood (Vb v ) in the volume ratio 3:7.…”

Section: Circulatory Transfer Functionmentioning

confidence: 99%

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Physiological control of diving behaviour in the Weddell sealLeptonychotes weddelli: a model based on cardiorespiratory control theory

Stephenson

2005

Journal of Experimental Biology

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Despite being obligate air breathers, many species of marine mammal are capable of spending most of their lives submerged in water. How they do this has been a subject of intense interest to physiologists for over a century, yet we still do not have a detailed understanding of the physiological mechanisms underlying this behaviour. What are the proximate mechanisms that trigger the 'decisions' to submerge and return to the surface? The present study proposes a model intended to address this question, based on fundamental concepts of cardiorespiratory control. Two basic hypotheses are examined by computer simulation, using a mathematical model of the mammalian cardiorespiratory control system with parameter values for an adult Weddell seal: (1) that the control of diving can be considered to be a respiratory control problem, and (2) that dives are initiated and maintained by disfacilitation of respiratory drive, not inhibition. Computer simulations confirmed the plausibility of these hypotheses. Simulated diving behaviour and physiological responses (ventilation, cardiac output, blood and tissue gas tensions) were consistent with published data from freely diving Weddell seals. Dives up to the estimated aerobic dive limit (ADL, 18-25·min) could be simulated without the need for active inhibition of breathing in this model. This theoretical analysis suggests that the most important physiological adjustments occur during the surface interval phase of the dive cycle and include hyperventilation accompanied by high cardiac output, appropriate regulation of cerebral blood flow and central chemoreceptor threshold shifts. During dives, cardiac output, distribution of peripheral blood flow, splenic contraction and peripheral chemoreflex drives were found to modulate physiological and behavioural responses, but were not essential for simulated dives to occur. The main conclusion from this study is that the central chemoreceptor may be an important mechanism involved in the regulation of diving behaviour, implying that CO 2 , not O 2 , is the key regulatory variable in this model. This model includes and extends the ADL concept and suggests an explicit mechanism by which the respiratory control system may play a central role in the regulation of diving behaviour. It is likely that respiratory mechanisms are an important component of a hierarchical behavioural control system and further studies are required to test the qualitative and quantitative validity of the model.

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“…However, Carter et al (1959) have measured the pulmonary-artery to radial-artery MTT in healthy supine adults at rest and found it to be 19.5 s, while T D was 11.7 s. Grace et al (1957) report a right heart-to-radial artery T D of 10.7 s in resting subjects. Both groups used slug injections of dye and a single sampling site; a method, which was shown by Lange et al (1966) to prolong the MTT-T D difference by some 6 s due to dispersion of the dye signal at the site of injection without affecting the MTT value. This would explain why there is a good agreement between the MTT values of Carter et al (1959) and the resting MTT values of the present investigation (19.5 and 18.2 s, respectively), while values for the MTT T D difference deviate.…”

Section: Blood Flow and Circulatory Transfer During Rest And Exercisementioning

confidence: 99%

Time components of circulatory transport from the lungs to a peripheral artery in humans

et al. 2006

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Blood gas changes occurring in the lung undergo delay and damping on their way to a peripheral artery sampling site. Knowledge of the time components of circulatory transfer is important for the understanding of respiratory control and cardiovascular reflexes in response to blood gas transients. Providing steady state with regard to VA/Q distribution, cardiac output and peripheral blood flow, the relationship between the time courses of small end-tidal and peripheral PO2 changes is determined by the transfer function of the interposed vascular segment. This transfer function, expressed as delay time TD and mean transit time (MTT), was measured in six well-trained subjects, allowing the calculation of arterial time-courses from end-tidal to the reverse. They were studied at rest and during four different dynamic leg exercise intensities in the supine posture. TD and MTT amounted to 15.8 +/- 1.7 (mean +/- SEM) and 18.3 +/- 2.1 s at rest and were shortened to 7.7 +/- 0.6 and 11.5 +/- 1.8 s during exercise at 170 W. The shortening of TD and MTT did not appear to be simply an inverse function of cardiac output, suggesting that the shortening occurs in the central circulatory segment but not in the arm segment.

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Pulmonary to arterial circulatory transfer function: importance in respiratory control.

Cited by 42 publications

References 0 publications

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

Impact of changes in inspired oxygen and carbon dioxide on respiratory instability in the lamb

Physiological control of diving behaviour in the Weddell sealLeptonychotes weddelli: a model based on cardiorespiratory control theory

Time components of circulatory transport from the lungs to a peripheral artery in humans

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