A model for the relation between respiratory neural and mechanical outputs. II. Methods

1981 ◽  
Vol 51 (4) ◽  
pp. 979-989 ◽  
Author(s):  
W. Riddle ◽  
M. Younes
Keyword(s):  
Theoretical Analysis ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Muscle Activation ◽  
Indirect Evidence ◽  
Present Communication ◽  
Inspiratory Muscles ◽  
Flow Profiles ◽  
Preceding Communication ◽  
Pressure Output

In the preceding communication we developed a model for the conversion of neural output to mechanical output. We were left with two qualitative uncertainties, namely, the relation between neural output and isometric pressure, and the behavior of inspiratory muscles during expiratory flow; and two quantitative uncertainties concerning the effect of configurational pathway on pressure output, and the slope of the pressure-flow relation. For each of the above uncertainties we made certain assumptions based on indirect evidence but defined reasonable error limits. In the present communication we describe the method of implementing the model and evaluate the significance, in terms of spirometric output, of possible errors in the assumptions. Volume and flow profiles were generated from different neural output profiles. Analysis was repeated when the different assumptions were systematically altered within the limits set by the previous theoretical analysis. We conclude that the pattern of inspiratory muscle activation during spontaneous breathing and the existence of several mechanical interactions within the respiratory system combine to render spirometric output fairly insensitive to most potential errors in our assumptions.

Mechanical aspects of chest wall distortion

1985 ◽  
Vol 59 (2) ◽  
pp. 295-304 ◽  
Author(s):  
J. P. Mortola ◽  
M. Saetta ◽  
G. Fox ◽  
B. Smith ◽  
S. Weeks
Keyword(s):  
Tidal Volume ◽  
Respiratory System ◽  
Volume Change ◽  
Spontaneous Breathing ◽  
Relaxation Curve ◽  
Abdominal Pressure ◽  
Human Infants ◽  
Adult Rats ◽  
Inspiratory Muscles ◽  
Phrenic Stimulation

During passive inflation of the respiratory system, the rib cage (RC) expands because the pressure applied to it [approximately equal to abdominal pressure (Pab)] increases. Similar Pab-tidal volume (VT) relationships between passive and spontaneous inspirations would occur only if 1) Pab acts on RC equally in the two situations (no distortion) or 2) the extradiaphragmatic inspiratory muscles expand RC, compensating for distortion. In anesthetized adult rats and in sleeping human infants the passive relationships between VT and Pab or abdomen motion (AB) were constructed by occluding the airways during expiration. For a given Pab (or AB) in active breathing VT averaged 55% (rats) and 49% (infants) of the passive volume change. With phrenic stimulation in rats VT was only slightly less than during spontaneous breathing, indicating that, in the latter case, the respiratory system was essentially driven only by the diaphragm. In both species occasional breaths with large RC expansion occurred, and VT was then equal to or larger than the passive volume at iso-Pab. We conclude that 1) RC distortion decreases VT to approximately half of the passive value and 2) being on the relaxation curve reflects “compensated” distortion and not absence of it.

Mechanics of the respiratory system in the newborn tammar wallaby

2002 ◽  
Vol 205 (4) ◽  
pp. 533-538 ◽  
Author(s):  
P. M. MacFarlane ◽  
P. B. Frappell ◽  
J. P. Mortola
Keyword(s):  
Respiratory System ◽  
Spontaneous Breathing ◽  
Minute Ventilation ◽  
Pulmonary Ventilation ◽  
Age Groups ◽  
Mechanical Efficiency ◽  
Tammar Wallaby ◽  
Ventilatory Equivalent ◽  
Rate Of Oxygen Consumption ◽  
Respiratory System Resistance

SUMMARY We investigated whether the mechanical properties of the respiratory system represent a major constraint to spontaneous breathing in the newborn tammar wallaby Macropus eugenii, which is born after a very short gestation (approximately 28 days, birth mass approximately 380 mg). The rate of oxygen consumption (V̇O2) through the skin was approximately 33 % of the total V̇O2 at day 1 and approximately 14 % at day 6. The mass-specific resting minute ventilation (V̇e) and the ventilatory equivalent (V̇e/V̇O2) were approximately the same at the two ages, with a breathing pattern significantly deeper and slower at day 1. The mass-specific compliance of the respiratory system (Crs) did not differ significantly between the two age groups and was close to the values predicted from measurements in eutherian newborns. Mass-specific respiratory system resistance (Rrs) at day 1 was higher than at day 6, and also higher than in eutherian newborns. Chest distortion, quantified as the degree of abdominal motion during spontaneous breathing compared with that required to inflate the lungs passively, at day 1 was very large, whereas it was modest at day 6. We conclude that, in the tammar wallaby at birth, the high resistance of the respiratory system and the distortion of the chest wall greatly reduce the mechanical efficiency of breathing. At this age, gas exchange through the skin is therefore an important complement to pulmonary ventilation.

Effects of diaphragmatic ischemia on the inspiratory motor drive

1992 ◽  
Vol 72 (2) ◽  
pp. 447-454 ◽  
Author(s):  
J. S. Teitelbaum ◽  
S. A. Magder ◽  
C. Roussos ◽  
S. N. Hussain
Keyword(s):  
Muscle Activation ◽  
Systemic Circulation ◽  
Progressive Increase ◽  
Emg Activity ◽  
Motor Drive ◽  
Inspiratory Muscles ◽  
Left Diaphragm ◽  
Inspiratory Motor ◽  
Phrenic Artery ◽  
Left And Right

To assess the effect of diaphragmatic ischemia on the inspiratory motor drive, we studied the in situ isolated and innervated left diaphragm in anesthetized, vagotomized, and mechanically ventilated dogs. The arterial and venous vessels of the left diaphragm were catheterized and isolated from the systemic circulation. Inspiratory muscle activation was assessed by recording the integrated electromyographic (EMG) activity of the left and right costal diaphragms and parasternal intercostal and alae nasi muscles. Tension generated by the left diaphragm during spontaneous breathing attempts was also measured. In eight animals, left diaphragmatic ischemia was induced by occluding the phrenic artery for 20 min, followed by 10 min of reperfusion. This elicited a progressive increase in EMG activity of the left and right diaphragms and parasternal and alae nasi muscles to 170, 157, 152, and 128% of baseline values, respectively, an increase in the frequency of breathing efforts, and no change in left diaphragmatic spontaneous tension. Thus the ratio of left diaphragmatic EMG to tension rose progressively during ischemia. During reperfusion, only the frequency of breathing efforts and alae nasi EMG recovered completely. In four additional animals, left diaphragmatic ischemia was induced after the left phrenic nerve was sectioned. Neither EMG activity of inspiratory muscles nor respiratory timing changed significantly during ischemia. In conclusion, diaphragmatic ischemia increases inspiratory motor drive through activation of phrenic afferents. The changes in alae nasi activity and respiratory timing indicate that this influence is achieved through supraspinal pathways.

Diaphragm electrical activity during negative lower torso pressure in quadriplegic men

1981 ◽  
Vol 51 (3) ◽  
pp. 654-659 ◽  
Author(s):  
R. B. Banzett ◽  
G. F. Inbar ◽  
R. Brown ◽  
M. Goldman ◽  
A. Rossier ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Tidal Volume ◽  
Respiratory System ◽  
Afferent Pathways ◽  
Co2 Partial Pressure ◽  
Inspiratory Muscles ◽  
Spinal Lesions ◽  
Diaphragm Electrical Activity ◽  
End Tidal ◽  
End Tidal Co2

We recorded the diaphragm electromyogram (EMG) of quadriplegic men before and during exposure of the lower torso to continuous negative pressure, which caused shortening of the inspiratory muscles by expanding the respiratory system by one tidal volume. The moving-time-averaged diaphragm EMG was larger during expansion of the respiratory system. When we repeated the experiment with subjects who breathed through a mouthpiece, we found qualitatively similar EMG changes and little or no change in tidal volume or end-tidal CO2 partial pressure. When the pressure was applied or removed rapidly, changes in EMG occurred within one or two breaths. Because end-tidal CO2 partial pressure did not increase, and because the response was rapid, we suggest that the response results from proprioceptive, rather than chemoreceptive, reflexes. As most of these men had complete spinal lesions at C6 or C7 the afferent pathways are likely to be vagal or phrenic.

scholarly journals Mechanical power normalized to lung-thorax compliance indicates weaning readiness in prolonged ventilated patients

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Alessandro Ghiani ◽  
Joanna Paderewska ◽  
Swenja Walcher ◽  
Konstantinos Tsitouras ◽  
Claus Neurohr ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Logistic Regression ◽  
Respiratory System ◽  
Spontaneous Breathing ◽  
Characteristic Curve ◽  
Spontaneous Breathing Trial ◽  
Mechanical Power ◽  
Binary Logistic Regression Model ◽  
Weaning Failure ◽  
Ventilated Patients

AbstractSince critical respiratory muscle workload is a significant determinant of weaning failure, applied mechanical power (MP) during artificial ventilation may serve for readiness testing before proceeding on a spontaneous breathing trial (SBT). Secondary analysis of a prospective, observational study in 130 prolonged ventilated, tracheotomized patients. Calculated MP’s predictive SBT outcome performance was determined using the area under receiver operating characteristic curve (AUROC), measures derived from k-fold cross-validation (likelihood ratios, Matthew's correlation coefficient [MCC]), and a multivariable binary logistic regression model. Thirty (23.1%) patients failed the SBT, with absolute MP presenting poor discriminatory ability (MCC 0.26; AUROC 0.68, 95%CI [0.59‒0.75], p = 0.002), considerably improved when normalized to lung-thorax compliance (LTCdyn-MP, MCC 0.37; AUROC 0.76, 95%CI [0.68‒0.83], p < 0.001) and mechanical ventilation PaCO2 (so-called power index of the respiratory system [PIrs]: MCC 0.42; AUROC 0.81 [0.73‒0.87], p < 0.001). In the logistic regression analysis, PIrs (OR 1.48 per 1000 cmH2O2/min, 95%CI [1.24‒1.76], p < 0.001) and its components LTCdyn-MP (1.25 per 1000 cmH2O2/min, [1.06‒1.46], p < 0.001) and mechanical ventilation PaCO2 (1.17 [1.06‒1.28], p < 0.001) were independently related to SBT failure. MP normalized to respiratory system compliance may help identify prolonged mechanically ventilated patients ready for spontaneous breathing.

Effect of curare on maximum static PV relationships of the respiratory system

1978 ◽  
Vol 44 (4) ◽  
pp. 589-595 ◽  
Author(s):  
N. A. Saunders ◽  
J. R. Rigg ◽  
L. D. Pengelly ◽  
E. J. Campbell
Keyword(s):  
Muscle Weakness ◽  
Respiratory System ◽  
Marked Change ◽  
Maximum Effect ◽  
Unequal Distribution ◽  
Inspiratory Muscles ◽  
Static Mechanical ◽  
Expiratory Muscles ◽  
Muscle Groups ◽  
Static Mechanical Properties

The effect of respiratory muscle weakness on the maximum static pressure-volume (PV) characteristics of the respiratory system was studied in four healthy males infused slowly with d-tubocurarine (dtc). Inspiratory capacity (IC), expiratory reserve volume (ERV), maximum static inspiratory and expiratory mouth pressures at four lung volumes, and handgrip were measured during induction of, and recovery from muscle weakness. The maximum effect of dtc varied among the muscle groups tested; peripheral muscles were most severely affected, expiratory muscles moderately, and inspiratory muscles least affected. At each level of weakness studied, decreases of IC and ERV were proportional to decreases of maximum static mouth pressures. Vital capacity, measured at each level of weakness was much less than values predicted from the static mechanical properties of the respiratory system. Our findings suggest that the marked change in the extremes of lung volume during submaximal neuromuscular blockade (SMNB) is due, in part, to unequal distribution of muscle weakness, reflected by decreased ability to change ribcage dimensions even at modest levels of SMNB.

Decay of inspiratory muscle pressure during expiration in anesthetized cats

1983 ◽  
Vol 54 (2) ◽  
pp. 408-413 ◽  
Author(s):  
W. A. Zin ◽  
L. D. Pengelly ◽  
J. Milic-Emili
Keyword(s):  
Respiratory System ◽  
Time Course ◽  
Pentobarbital Sodium ◽  
Airway Occlusion ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Resistive Loads ◽  
The Moment ◽  
Spontaneously Breathing

In six spontaneously breathing anesthetized cats (pentobarbital sodium, 35 mg/kg) we studied the antagonistic pressure developed by the inspiratory muscles during expiration (PmusI). This was accomplished in two ways: 1) with our previously reported method (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 52: 1266–1271, 1982) based on the measurement of changes in lung volume and airflow during spontaneous expiration, together with determination of the total passive respiratory system elastance and resistance; and 2) measurement of the time course of changes in tracheal/pressure after airway occlusion at end inspiration, up to the moment when the inspiratory muscles become completely relaxed. The agreement between the two methods is generally good, both in the amplitude of PmusI and in its time course. We also applied the first method to spontaneous expirations through added linear resistive loads. These did not alter the relative decay of PmusI. Thus in anesthetized cats the braking action of the inspiratory muscles does not decrease when expiratory resistive loads are added, i.e., when such braking is clearly not required.

Cardiopulmonary adaptations to pneumonectomy in dogs. III. Ventilatory power requirements and muscle structure

1994 ◽  
Vol 76 (5) ◽  
pp. 2191-2198 ◽  
Author(s):  
C. C. Hsia ◽  
L. F. Herazo ◽  
M. Ramanathan ◽  
H. Claassen ◽  
F. Fryder-Doffey ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Respiratory System ◽  
Total Mass ◽  
Mechanical Characteristics ◽  
Minute Ventilation ◽  
Left Lung ◽  
Elastic Recoil ◽  
Inspiratory Muscles ◽  
Right Thoracotomy ◽  
The Right

Static and dynamic mechanical characteristics of the respiratory system were measured in five adult foxhounds 6–15 mo after right pneumonectomy (R-PNX) and in five matched foxhounds that underwent right thoracotomy without pneumonectomy (Sham). In R-PNX dogs, elastic recoil was lower than that in the left lung of Sham dogs. On exercise, absolute ventilatory power requirements of the lung and its components were measured, i.e., power requirements to overcome elastic and viscous resistances of the lung as well as power requirements during inspiration and expiration. All components were higher for a given minute ventilation in R-PNX dogs than in both lungs of Sham dogs. Ventilatory power requirements after R-PNX were also higher than in three adult foxhounds after left PNX studied previously by the same techniques. After R-PNX, the mass of the right costal diaphragm and total mass of inspiratory muscles were greater than in Sham dogs. There were no significant differences in ultrastructural features of the costal diaphragm. The unilateral increase in muscle mass is likely the result of chronic elevation and stretch of the right costal diaphragm after R-PNX.

Pliometric activity of inspiratory muscles: maximal pressure-flow curves

1987 ◽  
Vol 62 (1) ◽  
pp. 322-327 ◽  
Author(s):  
G. P. Topulos ◽  
M. B. Reid ◽  
D. E. Leith
Keyword(s):  
Respiratory System ◽  
Flow Characteristics ◽  
Esophageal Pressure ◽  
Flow Curves ◽  
Reduced Pressure ◽  
Pressure Flow ◽  
Inspiratory Muscles ◽  
Airway Opening ◽  
Maximal Pressure ◽  
Force Velocity

We tested the hypothesis that inspiratory muscles, like other skeletal muscles, would exert greater force under pliometric conditions (being lengthened while active) than under isometric or miometric (active shortening) conditions. Maximal inspiratory pressure-flow curves of the respiratory system are analogous to the force-velocity curves for isolated muscle (Agostoni and Fenn, J. Appl. Physiol. 15:349–353, 1960). We measured esophageal pressure (Pes) and plethysmographic flow (V) at relaxation volume of the respiratory system in six trained subjects inspiring maximally through graded resistors (miometric), against a closed airway (isometric), and while constant expiratory flows were forced by a reduced pressure source at the airway opening (pliometric). Pes varied inversely with V and this trend continued into the pliometric range. In addition we found that the pressure-flow characteristics of the rib cage and of the abdomen are similar to those for the chest wall as a whole. The mechanical and energetic advantages of muscle activity under pliometric conditions may be available to some inspiratory muscles in both normal and pathological situations.

scholarly journals Performance Evaluation of Fixed Sample Entropy in Myographic Signals for Inspiratory Muscle Activity Estimation

Entropy ◽  
2019 ◽  
Vol 21 (2) ◽  
pp. 183 ◽  
Author(s):  
Manuel Lozano-García ◽  
Luis Estrada ◽  
Raimon Jané
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Cardiac Activity ◽  
Sample Entropy ◽  
Inspiratory Muscle ◽  
Chronic Obstructive ◽  
Inspiratory Muscles ◽  
Fixed Sample ◽  
Cross Covariance ◽  
Activity Estimation

Fixed sample entropy (fSampEn) has been successfully applied to myographic signals for inspiratory muscle activity estimation, attenuating interference from cardiac activity. However, several values have been suggested for fSampEn parameters depending on the application, and there is no consensus standard for optimum values. This study aimed to perform a thorough evaluation of the performance of the most relevant fSampEn parameters in myographic respiratory signals, and to propose, for the first time, a set of optimal general fSampEn parameters for a proper estimation of inspiratory muscle activity. Different combinations of fSampEn parameters were used to calculate fSampEn in both non-invasive and the gold standard invasive myographic respiratory signals. All signals were recorded in a heterogeneous population of healthy subjects and chronic obstructive pulmonary disease patients during loaded breathing, thus allowing the performance of fSampEn to be evaluated for a variety of inspiratory muscle activation levels. The performance of fSampEn was assessed by means of the cross-covariance of fSampEn time-series and both mouth and transdiaphragmatic pressures generated by inspiratory muscles. A set of optimal general fSampEn parameters was proposed, allowing fSampEn of different subjects to be compared and contributing to improving the assessment of inspiratory muscle activity in health and disease.

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