Rapidly adapting receptors monitor lung compliance in spontaneously breathing dogs

1990 ◽  
Vol 68 (5) ◽  
pp. 1997-2005 ◽  
Author(s):  
T. E. Pisarri ◽  
A. Jonzon ◽  
J. C. Coleridge ◽  
H. M. Coleridge
Keyword(s):  
Tidal Volume ◽  
Spontaneous Breathing ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Vagus Nerves ◽  
Concomitant Increase ◽  
Inflatable Cuff ◽  
Lung Expansion ◽  
Dynamic Lung Compliance ◽  
Spontaneously Breathing

We examined the ability of rapidly adapting receptors (RARs) to monitor changes in dynamic lung compliance (Cdyn) in anesthetized spontaneously breathing dogs by recording RAR impulses from the vagus nerves. We decreased Cdyn in steps through the physiological range by briefly restricting lung expansion with an inflatable cuff around the chest and recording the response after deflating the cuff; we restored Cdyn to control by hyperinflating the lungs. Of 45 RARs, 34 were stimulated by a 40 +/- 2% reduction in Cdyn, their inspiratory discharge increasing on average more than threefold. Two-thirds of responsive RARs were stimulated by less than or equal to 20% reductions in Cdyn; in most, firing increased proportionately with lung stiffness (1/Cdyn) as Cdyn was decreased further. Stimulation by reduced Cdyn was not simply a function of the concomitant increase in transpulmonary pressure, because similar increases in pressure produced by increasing tidal volume produced smaller increases in firing. RAR stimulation was unaffected by atropine and, hence, was not dependent on neurally mediated changes in bronchomotor tone. Our results indicate that during spontaneous breathing RARs provide a signal inversely proportional to Cdyn.

Dynamic lung compliance in newborn and adult cats

1986 ◽  
Vol 60 (3) ◽  
pp. 743-750 ◽  
Author(s):  
K. J. Sullivan ◽  
J. P. Mortola
Keyword(s):  
Stress Relaxation ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Theoretical Treatment ◽  
The Difference ◽  
Adult Cats ◽  
Isolated Lungs ◽  
Dynamic Lung Compliance ◽  
Volume History ◽  
Lung Stress

Static (Cstat) and dynamic (Cdyn) lung compliance and lung stress relaxation were examined in isolated lungs of newborn kittens and adult cats. Cstat was determined by increasing volume in increments and recording the corresponding change in pressure; Cdyn was calculated as the ratio of the changes in volume to transpulmonary pressure between points of zero flow at ventilation frequencies between 10 and 110 cycles/min. Lung volume history, end-inflation volume, and end-deflation pressure were maintained constant. At the lowest frequency of ventilation, Cdyn was less than Cstat, the difference being greater in newborns. Between 20 and 100 cycles/min, Cdyn of the newborn lung remained constant, whereas Cdyn of the adult lung decreased after 60 cycles/min. At all frequencies, the rate of stress relaxation, measured as the decay in transpulmonary pressure during maintained inflation, was greater in newborns than in adults. The frequency response of Cdyn in kittens, together with the relatively greater rate of stress relaxation, suggests that viscoelasticity contributes more to the dynamic stiffening of the lung in newborns than in adults. A theoretical treatment of the data based on a linear model of viscoelasticity supports this conclusion.

scholarly journals A Protective Tidal Volume Adapted To Lung Compliance and The PEEP Level With Lowest Transpulmonary Driving Pressure May Be Determined By a Rapid PEEP-Step Procedure

2021 ◽  
Author(s):  
Christina Grivans ◽  
Ola Stenqvist
Keyword(s):  
Body Weight ◽  
Tidal Volume ◽  
Peep Level ◽  
Ideal Body Weight ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Lung Compliance ◽  
Driving Pressure ◽  
Step Procedure ◽  
Ideal Body

Abstract Background: A protective ventilation strategy should be based on lung mechanics and transpulmonary pressure, as this is the pressure that directly “hits” the lung. Esophageal pressure has been used for this purpose but has not gained widespread clinical acceptance. Instead, respiratory system mechanics and airway driving pressure have been used as surrogate measures. We have shown that the lung pressure/volume (P/V) curve coincides with the line connecting the end-expiratory airway P/V points of a PEEP trial. Consequently, transpulmonary pressure increases as much as PEEP and lung compliance (CL) can be determined as ΔEELV/ΔPEEP and transpulmonary driving pressure (ΔPTP) as tidal volume divided by ΔEELV/ΔPEEP.Methods: In ten patients with acute respiratory failure, ΔEELV was measured during each 4 cmH2O PEEP-step from 0 to 16 cmH2O and CL for each PEEP interval calculated as ΔEELV/ΔPEEP giving a lung P/V curve for the whole PEEP trial. Similarily, a lung P/V curve was obtained also for the PEEP levels 8, 12, and 16 cmH2O only.Results: A two-step PEEP procedure starting from a clinical PEEP level of 8 cmH2O gave almost identical lung P/V curves as the four PEEP-step procedure. The lung P/V curves showed a marked individual variation with an over-all CL (CLoa ) 50-137 ml/cmH2O. ΔPTP of a tidal volume of 6-7 ml/kg ideal body weight divided by CLoa ranged from 8.6-2.8 cmH2O, while ΔPTP of tidal volume adapted to CLoa ranged from 3.3 in the patient with lowest to 4.3 cmH 2 O in the patient with highest CLoa . The ratio of airway driving pressure to transpulmonary driving pressure (ΔPTP/ΔPAW) varied between patients and changed with PEEP, reducing the value of ΔPAW as surrogate for ΔPTP in individual patients.Conclusion: Only a two PEEP-step procedure is required for obtaining a lung P/V curve from baseline clinical PEEP to end-inspiration at the highest PEEP level, i.e. without esophageal pressure measurements. The best-fit equation for the curve can be used to determine a tidal volume related to lung compliance instead of ideal body weight and the PEEP level where transpulmonary driving pressure is lowest and possibly least injurious for any given tidal volume.

Effects of pulmonary air embolism on discharge of slowly adapting pulmonary stretch receptors

1994 ◽  
Vol 76 (1) ◽  
pp. 97-103 ◽  
Author(s):  
B. P. Lee ◽  
H. F. Chen ◽  
F. C. Hsu ◽  
T. B. Kuo ◽  
M. H. Yang
Keyword(s):  
Fiber Type ◽  
Air Embolism ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Group I ◽  
Airway Collapse ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
Close Relationship ◽  
Dynamic Lung Compliance

Pulmonary air embolism (PAE) usually causes small-airway collapse. Local transpulmonary pressure (Ptr) is thought to be closely associated with the activity of slowly adapting pulmonary stretch receptors (SAPSRs). To test whether discharge of SAPSRs located distal to collapsed airways is closely related to the overall Ptr, we studied 65 SAPSRs in anesthetized paralyzed open-chest dogs that were ventilated at constant tidal volume and frequency. PAE increased both Ptr and total pulmonary resistance but decreased dynamic lung compliance. Three groups of SAPSRs were identified on the basis of their locations in intrapulmonary airways. Group I had 29 SAPSRs located in airways < 1 mm in diameter. Group II had 10 SAPSRs that were found in intrapulmonary airways between 1 and 2 mm in diameter. PAE decreased the activity of 31 of the 39 SAPSRs in these two groups. Their activity during PAE was not related to Ptr. The 26 SAPSRs in group III were in airways > 2 mm in diameter. PAE increased the peak firing rate of 18 of these receptors, and there was a close relationship between the discharge frequency of these SAPSRs and the Ptr during PAE. In groups I and II, the dissociation between Ptr and SAPSR activity during PAE may have been caused by peripheral airway collapse. Activity of central fibers was blocked at higher temperatures than activity of peripheral fibers. We suggest that the response of a SAPSR to PAE depends on the location of the receptor within the lungs, and we speculate that threshold and fiber type are also related to location.

Comparative aspects of the dynamics of breathing in newborn mammals

1983 ◽  
Vol 54 (5) ◽  
pp. 1229-1235 ◽  
Author(s):  
J. P. Mortola
Keyword(s):  
Body Size ◽  
Respiratory System ◽  
Dynamic Properties ◽  
Upper Airway ◽  
Lung Compliance ◽  
Expiratory Time ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Dynamic Lung Compliance ◽  
Spontaneously Breathing

Static and dynamic properties of the respiratory system have been studied in anesthetized, tracheostomized newborns of six species, ranging in size from rats to piglets. Respiratory system compliance (Crs), total resistance of respiratory system (Rrs), and expiratory time constant (tau) have been measured in the paralyzed passively ventilated animals. Crs is found to be proportional to body weight (BW0.80) and Rrs to BW-0.75; tau is independent of body size, the shortest value being in kittens and guinea pigs and a value of about 0.14 s in the other species. Including the upper airway resistance, tau becomes approximately 0.22 s. This value is similar to the expiratory time of the fastest breathing species; therefore in the smallest species the high breathing rate can be regarded as a mechanism to raise end-expiratory level. On a few occasions, dynamic lung compliance and pulmonary resistance, measured in spontaneously breathing kittens, puppies, and piglets were, respectively, smaller and larger than Crs and Rrs, suggesting that the hysteresis of the pressure-volume curve may be substantial. Rrs was almost linear within the volume and flow range investigated, with the Rohrer's constant K2 always being less than 2.5% of K1. The Reynolds number increases with body size (alpha BW0.51) more than is predictable from the changes in tracheal diameter, since the tracheal flow velocity is not an interspecific constant.

Rapidly adapting receptor activity in dogs is inversely related to lung compliance

1986 ◽  
Vol 61 (5) ◽  
pp. 1980-1987 ◽  
Author(s):  
A. Jonzon ◽  
T. E. Pisarri ◽  
J. C. Coleridge ◽  
H. M. Coleridge
Keyword(s):  
Inflation Rate ◽  
Impulse Activity ◽  
Lung Compliance ◽  
Excitatory Input ◽  
Rate Of Change ◽  
Positive End Expiratory Pressure ◽  
Vagus Nerves ◽  
Constant Rate ◽  
Length Constant ◽  
Dynamic Lung Compliance

We examined the response of pulmonary rapidly adapting receptors (RAR′s) to changes in dynamic lung compliance (Cdyn) in the physiological range. RAR impulse activity was recorded from the cervical vagus nerves in anesthetized open-chest dogs whose lungs were ventilated at constant rate and tidal volume (VT), with a positive end-expiratory pressure (PEEP) of 3–4 cmH2O. After hyperinflation to produce maximal Cdyn, RAR′s were silent or fired sparsely and irregularly. Reducing Cdyn in steps by briefly removing PEEP increased firing proportionately, and RAR′s began to discharge vigorously in inflation. Activity was restored to control by hyperinflating the lungs. Activity also increased when we increased inflation rate, and hence the rate of change of airway pressure (dP/dt), by reducing inflation time, keeping VT and cycle length constant. RAR′s were stimulated more when dP/dt was increased by reducing compliance than when dP/dt was increased by increasing inflation rate. We conclude that RAR′s are sensitive to changes in Cdyn and speculate that excitatory input from RAR′s may help to maintain VT as the lungs become stiffer.

scholarly journals Protective PEEP and Lung Capacity May Be Determined by a Rapid PEEP-step Procedure

2021 ◽  
Author(s):  
Christina Grivans ◽  
Ola Stenqvist
Keyword(s):  
Tidal Volume ◽  
Peep Level ◽  
Transpulmonary Pressure ◽  
Esophageal Pressure ◽  
Plateau Pressure ◽  
Lung Compliance ◽  
Driving Pressure ◽  
High Peep ◽  
Step Procedure ◽  
Protective Ventilation Strategy

Abstract Background: A protective ventilation strategy should be based on assessment of lung mechanics and transpulmonary pressure, as this is the pressure that directly “hits” the lung. Esophageal pressure has been used for this purpose but has not gained widespread clinical acceptance. Instead, respiratory system mechanics and airway driving pressure have been used as surrogate measures. We have shown that the lung P/V curve coincides with the line connecting the end-expiratory airway P/V points of a PEEP trial. Consequently, transpulmonary pressure increases as much as PEEP is increased. If the change in end-expiratory lung volume (ΔEELV) is determined, lung compliance (CL) can be determined as ΔEELV/ΔPEEP and ΔPTP as tidal volume times ΔPEEP/ΔEELV. Methods: In ten patients with acute respiratory failure, ΔEELV was measured during each 4 cmH2O PEEP-step from 0 to 16 cmH2O and CL for each PEEP interval calculated as ΔEELV/ΔPEEP giving a lung P/V curve for the whole PEEP trial. Results: Lung P/V curves showed a marked individual variation with an overall lung compliance of 43–143 ml/cmH2O (total inspiratory volume divided by end-inspiratory transpulmonary plateau pressure at PEEP 16 cmH2O). The two patients with lowest lung compliance were non-responders to PEEP with decreasing lung compliance at high PEEP levels, indicating over-distension. Patients with higher lung compliance had a positive response to PEEP with successively higher lung compliance when increasing PEEP. A two-step PEEP procedure starting from a clinical PEEP level of 8 cmH2O gave almost identical lung P/V curves as the four PEEP-step procedure. The ratio of airway driving pressure (ΔPAW) to transpulmonary driving pressure (ΔPTP/ΔPAW) varied between patients and changed with PEEP, reducing the value of ΔPAW as surrogate for ΔPTP in individual patients. Conclusion: Separation of lung and chest wall mechanics can be achieved without esophageal pressure measurements if ΔEELV is determined when PEEP is changed . Only a two-step PEEP procedure is required for obtaining a lung P/V curve from baseline clinical PEEP to end-inspiration at the highest PEEP level, which can be used to determine the PEEP level where transpulmonary driving pressure is lowest and possibly least injurious for any given tidal volume.Trial registration: ClinicalTrials.gov, NCT04484727. Registered 24 July 2020 – Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT04484727?term=Lindgren%2C+Sophie&cntry=SE&draw=2&rank=1

Response of slowly adapting pulmonary stretch receptors to reduced lung compliance

1991 ◽  
Vol 71 (2) ◽  
pp. 425-431 ◽  
Author(s):  
J. Yu ◽  
T. E. Pisarri ◽  
J. C. Coleridge ◽  
H. M. Coleridge
Keyword(s):  
Steady State ◽  
Tidal Volume ◽  
Time Constant ◽  
Transpulmonary Pressure ◽  
Lung Compliance ◽  
Steady State Response ◽  
Positive End Expiratory Pressure ◽  
State Response ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors

We examined the steady-state response of slowly adapting pulmonary stretch receptors (SAPSRs) to reduced lung compliance in open-chest cats with lungs ventilated at eupneic rate and tidal volume (VT) and with a positive end-expiratory pressure (PEEP) of 3–4 cmH2O. Transient removal of PEEP decreased compliance by approximately 30% and increased transpulmonary pressure (Ptp) by 1–2.5 cmH2O. Reduction of compliance significantly decreased SAPSR discharge in deflation and caused a small increase in discharge at the peak of inflation; it had little effect on discharge averaged over the ventilatory cycle. Increasing VT to produce a comparable increase in Ptp significantly increased peak discharge. Thus unlike rapidly adapting receptors, whose discharge is increased more effectively by reduced compliance than by increased VT, SAPSRs are stimulated by increased VT but not by reduced compliance. We speculate that the most consistent effect of reduced compliance on SAPSRs (the decrease in deflation discharge) was due to the decreased time constant for deflation in the stiffer lung. This alteration in firing may contribute to the tachypnea evoked as the lungs become stiffer.

Pressure-volume curve of lung and lobes in kittens

1984 ◽  
Vol 56 (4) ◽  
pp. 948-953 ◽  
Author(s):  
J. P. Mortola ◽  
A. Rossi ◽  
L. Zocchi
Keyword(s):  
Mechanical Behavior ◽  
Weight Ratio ◽  
Transpulmonary Pressure ◽  
Random Order ◽  
Lung Parenchyma ◽  
Lung Compliance ◽  
Unit Weight ◽  
Maximal Volume ◽  
Volume Curve ◽  
Dynamic Lung Compliance

In the neonatal period, the incomplete aeration of the lung parenchyma and the presence of some pulmonary fluid could determine inequalities in the mechanical behavior of lung regions, favoring unevenness of ventilation distribution. We studied the pressure-volume (PV) curve of excised lungs of kittens in the 1st wk of life 1) by changing the volume a known amount and measuring the corresponding changes in transpulmonary pressure (PL) and 2) by ventilating them at a fixed PL at a rate of 20 cycles/min. An expiratory load equal to the value of PL at the resting volume of the respiratory system was added to avoid the collapse of the lung. A lobar bronchus was then tied, and the measurements were repeated. The difference in PV curves before and after ligature therefore represented the PV curve of the lobe. This was done for all the lobes (upper and middle right, lower right, lower left, upper left) in a random order. A total of 20 lungs and 61 lobes have been studied. Individual lobes were not different in terms of dry-to-wet weight ratio, compliance per unit weight, or per maximal volume and shape of the PV curve, indicating a similar mechanical behavior. Dynamic lung compliance averaged 76% +/- 15 SD of the static value, suggesting some degree of asynchronous behavior of lung regions or viscoelastic properties of the tissue.

Effect of lowering serum cholesterol on the composition of surfactant in adult rat lung

1997 ◽  
Vol 272 (1) ◽  
pp. L106-L114 ◽  
Author(s):  
K. G. Davidson ◽  
S. M. Acton ◽  
H. A. Barr ◽  
T. E. Nicholas
Keyword(s):  
Tidal Volume ◽  
Serum Cholesterol ◽  
Protein A ◽  
Lamellar Body ◽  
Principal Component ◽  
Surfactant Protein ◽  
Lung Compliance ◽  
Adult Rat ◽  
Alveolar Surfactant ◽  
Dynamic Lung Compliance

Treatment of rats with 10 mg.kg body wt-1 day-1 4-aminopyrazolo[3,4-d]pyrimidine (APP) for 2 days markedly reduced serum cholesterol and phospholipids. This was associated with large decreases in the principal component of alveolar surfactant, the disaturated phospholipids (DSP), in the lamellar body and in the tubular myelin-rich and -poor alveolar fractions, but with no concomitant change in cholesterol or surfactant protein A. These decreases in DSP were associated with a decrease in the synthesis of surfactant phospholipids. Despite these large changes in composition of alveolar surfactant, we could detect no change in either static or dynamic lung compliance. However, the treatment markedly increased both the minimum and maximum surface tension of the lipid extract of the tubular myelin-rich fraction, as measured by bubble surfactometry. Whereas these changes appeared unimportant in the isolated perfused lung at resting tidal volume, they were associated with edema after an increase in tidal volume. The ability of APP to inhibit phospholipid synthesis selectively makes it a useful tool in investigating the surfactant system.

Dynamic Lung Compliance and the Effect of Oxygen Breathing in Patients with Chronic Bronchitis

1970 ◽  
Vol 39 (4) ◽  
pp. 497-503
Author(s):  
T. W. Astin
Keyword(s):  
Tidal Volume ◽  
Chronic Bronchitis ◽  
Lung Compliance ◽  
Minute Volume ◽  
Physiological Dead Space ◽  
Oxygen Breathing ◽  
Airways Resistance ◽  
Effect Of Oxygen ◽  
Dynamic Lung Compliance ◽  
Ventilation Of The Lungs

1. Simultaneous measurements of the tidal volume and the intra-oesophageal pressure were made in fifteen hypoxaemic patients with chronic bronchitis during periods of air breathing and 30% oxygen breathing; values of dynamic lung compliance were obtained. 2. During the period of oxygen breathing, the dynamic lung compliance increased in fourteen of the patients (the mean increase was 28%). 3. The increase in dynamic lung compliance could not be accounted for by a change in the frequency of breathing, tidal volume or minute volume. 4. It is concluded that the increase in dynamic lung compliance reflected a reduction in airways resistance during oxygen breathing. It is suggested that this could lead to a change in the physiological dead space in the absence of any change in the overall ventilation of the lungs.

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