Single-breath method for measurement of respiratory mechanics in anesthetized animals

1982 ◽  
Vol 52 (5) ◽  
pp. 1266-1271 ◽  
Author(s):  
W. A. Zin ◽  
L. D. Pengelly ◽  
J. Milic-Emili
Keyword(s):  
Respiratory System ◽  
Flow Resistance ◽  
Respiratory Mechanics ◽  
Respiratory Muscles ◽  
Volume Flow ◽  
Single Breath ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Spontaneously Breathing ◽  
Single Breath Method

In six spontaneously breathing anesthetized cats (pentobarbital sodium, 35 mg/kg ip) airflow, changes in lung volume and tracheal pressure were measured. The airways were occluded at end inspiration (VT). During the ensuing period of apnea (Breuer-Hering inflation reflex), the animal relaxed the respiratory muscles and the passive compliance of the respiratory system (Crs) was computed by dividing VT by the tracheal pressure. While the animal was still relaxed, the airways were reopened, and during the ensuing relaxed expiration the volume-flow relationship was linear, the slope representing the time constant of the respiratory system: tau rs = Crs . Rrs, where Rrs is the flow resistance of the passive respiratory system. From the measured values of tau rs and Crs, Rrs was computed. With this information it was also possible to quantitate the antagonistic pressure developed by the inspiratory muscles during spontaneous expiration.

Interrupter technique for measurement of respiratory mechanics in anesthetized cats

1984 ◽  
Vol 56 (3) ◽  
pp. 681-690 ◽  
Author(s):  
S. B. Gottfried ◽  
A. Rossi ◽  
P. M. Calverley ◽  
L. Zocchi ◽  
J. Milic-Emili
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Flow Resistance ◽  
Muscle Relaxation ◽  
Esophageal Pressure ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Force Velocity ◽  
Spontaneously Breathing

In six spontaneously breathing anesthetized cats (pentobarbital sodium, 35 mg/kg ip), airflow, changes in lung volume, and tracheal and esophageal pressures were measured. Airflow was interrupted by brief airway occlusions during relaxed expirations (elicited via the Breuer-Hering inflation reflex) and throughout spontaneous breaths. A plateau in tracheal pressure occurred throughout relaxed expirations and the latter part of spontaneous expirations indicating respiratory muscle relaxation. Measurement of tracheal pressure, immediately preceding airflow, and corresponding volume enabled determination of respiratory system elastance and flow resistance. These were partitioned into lung and chest wall components using esophageal pressure. Respiratory system elastance was constant over the tidal volume range, divided approximately equally between the lung and chest wall. While the passive pressure-flow relationship for the respiratory system was linear, those for the lung and chest wall were curvilinear. Volume dependence of chest wall flow resistance was demonstrated. During inspiratory interruptions, tracheal pressure increased progressively; initial tracheal pressure was estimated by backward extrapolation. Inspiratory flow resistance of the lung and total respiratory system were constant. Force-velocity properties of the contracting inspiratory muscles contributed little to overall active resistance.

Interrupter technique for measurement of respiratory mechanics in anesthetized humans

1985 ◽  
Vol 59 (2) ◽  
pp. 647-652 ◽  
Author(s):  
S. B. Gottfried ◽  
B. D. Higgs ◽  
A. Rossi ◽  
F. Carli ◽  
P. M. Mengeot ◽  
...  
Keyword(s):  
Respiratory System ◽  
Respiratory Muscle ◽  
Respiratory Mechanics ◽  
Muscle Relaxation ◽  
Total System ◽  
Single Breath ◽  
Inspiratory Muscles ◽  
Tracheal Pressure ◽  
Respiratory System Resistance ◽  
Relationship Of

Flow (V), volume (V), and tracheal pressure (Ptr) were measured throughout a series of brief (100 ms) interruptions of expiratory V in six patients during anesthesia (halothane-N2O) and anesthesia-paralysis (succinylcholine). For the latter part of spontaneous expiration and throughout passive deflation during muscle paralysis, a plateau in postinterruption Ptr was observed, indicating respiratory muscle relaxation. Under these conditions, passive elastance of the total respiratory system (Ers) was determined as the plateau in postinterruption Ptr divided by the corresponding V. The pressure-flow relationship of the total system was determined by plotting the plateau in Ptr during interruption against the immediately preceding V. Ers averaged 23.5 +/- 1.9 (SD) cmH2O X l-1 during anesthesia and 25.5 +/- 5.4 cmH2O X l-1 during anesthesia-paralysis. Corresponding values of total respiratory system resistance were 2.0 +/- 0.8 and 1.9 +/- 0.6 cmH2O X l-1 X s, respectively. Respiratory mechanics determined during anesthesia paralysis using the single-breath method (W.A. Zin, L. D. Pengelly, and J. Milic-Emili, J. Appl. Physiol. 52: 1266–1271, 1982) were also similar. Early in spontaneous expiration, however, Ptr increased progressively during the period of interruption, reflecting the presence of gradually decreasing antagonistic (postinspiratory) pressure of the inspiratory muscles. In conclusion, the interrupter technique allows for simultaneous determination of the passive elastic as well as flow-resistive properties of the total respiratory system. The presence of a plateau in postinterruption Ptr may be employed as a useful and simple criterion to confirm the presence of respiratory muscle relaxation.

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.

Active inspiratory impedance in halothane-anesthetized humans

1983 ◽  
Vol 54 (6) ◽  
pp. 1477-1481 ◽  
Author(s):  
P. K. Behrakis ◽  
B. D. Higgs ◽  
A. Baydur ◽  
W. A. Zin ◽  
J. Milic-Emili
Keyword(s):  
Respiratory System ◽  
Flow Resistance ◽  
Linear Flow ◽  
Tracheal Pressure ◽  
Internal Impedance ◽  
Internal Mechanism ◽  
Spontaneously Breathing ◽  
Flow Resistances

We have used the method of Siafakas et al. (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 51: 109–121, 1981) to determine active elastance (E'rs) and flow resistance (R'rs) of the respiratory system in eight spontaneously breathing humans anesthetized with halothane. From measurements of flow (V) and volume (V) during unoccluded inspirations and of tracheal pressure (P0tr) during subsequent inspirations with the airways occluded at end expiration, we were able to compute E'rs and R'rs as slopes and intercepts of the following function: -P0tr/V = R'rs + E'rsV/V. These measurements were repeated during inspirations loaded with a series of linear flow resistances (delta R). Neither E'rs nor R'rs was significantly affected by delta R. On the average E'rs and R'rs were, respectively, 34.4 and 16.7% higher than the corresponding passive elastance and flow resistance of the respiratory system, indicating that during active breathing the internal impedance of the respiratory system increases. This provides an internal mechanism by which passive loads are compensated.

Respiratory mechanics during halothane anesthesia and anesthesia-paralysis in humans

1983 ◽  
Vol 55 (4) ◽  
pp. 1085-1092 ◽  
Author(s):  
P. K. Behrakis ◽  
B. D. Higgs ◽  
A. Baydur ◽  
W. A. Zin ◽  
J. Milic-Emili
Keyword(s):  
Flow Resistance ◽  
Respiratory Muscles ◽  
Inspiratory Muscle ◽  
Normal Limits ◽  
Muscle Work ◽  
Anesthetic Concentration ◽  
Tracheal Pressure ◽  
Measured Flow ◽  
Spontaneously Breathing ◽  
Relationship Of

In six spontaneously breathing anesthetized subjects [halothane approximately 1 maximum anesthetic concentration (MAC), 70% N2O-30% O2], we measured flow (V), volume (V), and tracheal pressure (Ptr). With airway occluded at end-inspiration tidal volume (VT), we measured Ptr when the subjects relaxed the respiratory muscles. Dividing relaxed Ptr by VT, total respiratory system elastance (Ers) was obtained. With the subject still relaxed, the occlusion was released to obtain the V-V relationship during the ensuing relaxed expiration. Under these conditions, the expiratory driving pressure is V X Ers, and thus the pressure-flow relationship of the system can be obtained. By subtracting the flow resistance of equipment, the intrinsic respiratory flow resistance (Rrs) is obtained. Similar measurements were repeated during anesthesia-paralysis (succinylcholine). Ers averaged 23.9 +/- 4 (+/- SD) during anesthesia and 21 +/- 1.8 cmH2O X 1(-1) during anesthesia-paralysis. The corresponding values of intrinsic Rrs were 1.6 +/- 0.7 and 1.9 +/- 0.9 cmH2O X 1(-1) X s, respectively. These results indicate that Ers increases substantially during anesthesia, whereas Rrs remains within the normal limits. Muscle paralysis has no significant effect on Ers and Rrs. We also provide the first measurements of inspiratory muscle activity and related negative work during spontaneous expiration in anesthetized humans. These show that 36-74% of the elastic energy stored during inspiration is wasted in terms of negative inspiratory muscle work.

Respiratory Mechanics of Sound Production in Chickens and Geese

1978 ◽  
Vol 72 (1) ◽  
pp. 229-250
Author(s):  
J. H. BRACKENBURY
Keyword(s):  
Respiratory System ◽  
Simultaneous Measurement ◽  
Sound Production ◽  
High Pressures ◽  
Respiratory Mechanics ◽  
Air Flow ◽  
Tracheal Pressure ◽  
Wide Range ◽  
Range Of Values ◽  
Respiratory Movements

1. Air flow, air sac pressure and tracheal pressure were measured in chickens and geese during a variety of different vocal and non-vocal activities. 2. Air flow and air sac pressure may rise to 500 ml s−1 and 60 cmH2O (6 103 N/m2) respectively during a crow in the chicken. During a sequence of honks in the goose the corresponding values are 650 ml s−1 and 25 cmH2O(2.5 × 10 3 N/m2) respectively. 3. The volume of air delivered through the respiratory system during a single crow is more than 400 ml, almost equivalent to the total volume of the lung air sac system. 4. The efficiency of the chicken syrinx as a sound producing instrument, estimated by comparing the sound energy radiated with the energy consumed in the expulsion of air during a crow, appears to be less than 2 %. 5. Cutting the paired sternotrachealis muscles had no effect on vocalization. 6. The measured rates of clucking, cheeping and honking in adult chickens, young chicks and adult geese respectively are comparable to the characteristic rates of panting in these animals. This points to a similarity in the nature of the respiratory movements involved in each case. 7. Simultaneous measurement of tracheal flow and pressure indicate that the glottis is capable of controlling air flow over a wide range of values in the presence of high pressures. During defaecation the valve is closed whilst during coughing it is wide open.

Electrical and mechanical activity of respiratory muscles during hypercapnia

1986 ◽  
Vol 61 (2) ◽  
pp. 719-727 ◽  
Author(s):  
E. van Lunteren ◽  
N. S. Cherniack
Keyword(s):  
Moving Average ◽  
Respiratory Muscles ◽  
Mechanical Activity ◽  
Intercostal Muscles ◽  
Co2 Rebreathing ◽  
Single Breath ◽  
Linear Relationships ◽  
Muscle Shortening ◽  
Close Relationship ◽  
Spontaneously Breathing

In nine anesthetized supine spontaneously breathing dogs, we compared moving average electromyograms (EMGs) of the costal diaphragm and the third parasternal intercostal muscles with their respective respiratory changes in length (measured by sonomicrometry). During resting O2 breathing the pattern of diaphragm and intercostal muscle inspiratory shortening paralleled the gradually incrementing pattern of their moving average EMGs. Progressive hypercapnia caused progressive increases in the amount and velocity of respiratory muscle inspiratory shortening. For both muscles there were linear relationships during the course of CO2 rebreathing between their peak moving average EMGs and total inspiratory shortening and between tidal volume and total inspiratory shortening. During single-breath airway occlusions, the electrical activity of both the diaphragm and intercostal muscles increased, but there were decreases in their tidal shortening. The extent of muscle shortening during occluded breaths was increased by hypercapnia, so that both muscles shortened more during occluded breaths under hypercapnic conditions (PCO2 up to 90 Torr) than during unoccluded breaths under normocapnic conditions. These results suggest that for the costal diaphragm and parasternal intercostal muscles there is a close relationship between their electrical and mechanical behavior during CO2 rebreathing, this relationship is substantially altered by occluding the airway for a single breath, and thoracic respiratory muscles do not contract quasi-isometrically during occluded breaths.

scholarly journals Single-breath method for assessing the viscoelastic properties of the respiratory system

1998 ◽  
Vol 12 (5) ◽  
pp. 1191-1196 ◽  
Author(s):  
V. Antonaglia ◽  
A. Grop ◽  
P. Demanins ◽  
F. Beltrame ◽  
U. Lucangelo ◽  
...  
Keyword(s):  
Respiratory System ◽  
Viscoelastic Properties ◽  
Single Breath ◽  
Single Breath Method

Effect of negative expiratory pressure on respiratory system flow resistance in awake snorers and nonsnorers

1999 ◽  
Vol 87 (3) ◽  
pp. 969-976 ◽  
Author(s):  
Claudio Tantucci ◽  
Alexandre Duguet ◽  
Anna Ferretti ◽  
Selma Mehiri ◽  
Isabelle Arnulf ◽  
...  
Keyword(s):  
Respiratory System ◽  
Supine Position ◽  
Flow Resistance ◽  
Upper Airway ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Upper Airways ◽  
Flow Interruption ◽  
Expiratory Flow ◽  
Spontaneously Breathing

In spontaneously breathing subjects, intrathoracic expiratory flow limitation can be detected by applying a negative expiratory pressure (NEP) at the mouth during tidal expiration. To assess whether NEP might increase upper airway resistance per se, the interrupter resistance of the respiratory system (Rint,rs) was computed with and without NEP by using the flow interruption technique in 12 awake healthy subjects, 6 nonsnorers (NS), and 6 nonapneic snorers (S). Expiratory flow (V˙) and Rint,rs were measured under control conditions with V˙ increased voluntarily and during random application of brief (0.2-s) NEP pulses from −1 to −7 cmH2O, in both the seated and supine position. In NS, Rint,rs with spontaneous increase inV˙ and with NEP was similar [3.10 ± 0.19 and 3.30 ± 0.18 cmH2O ⋅ l−1 ⋅ s at spontaneous V˙ of 1.0 ± 0.01 l/s and atV˙ of 1.1 ± 0.07 l/s with NEP (−5 cmH2O), respectively]. In S, a marked increase in Rint,rs was found at all levels of NEP ( P < 0.05). Rint,rs was 3.50 ± 0.44 and 8.97 ± 3.16 cmH2O ⋅ l−1 ⋅ s at spontaneous V˙ of 0.81 ± 0.02 l/s and atV˙ of 0.80 ± 0.17 l/s with NEP (−5 cmH2O), respectively ( P < 0.05). With NEP, Rint,rs was markedly higher in S than in NS both seated ( F = 8.77; P < 0.01) and supine ( F = 9.43; P < 0.01). In S,V˙ increased much less with NEP than in NS and was sometimes lower than without NEP, especially in the supine position. This study indicates that during wakefulness nonapneic S have more collapsible upper airways than do NS, as reflected by the marked increase in Rint,rs with NEP. The latter leads occasionally to an actual decrease in V˙ such as to invalidate the NEP method for detection of intrathoracic expiratory flow limitation.

Active and passive respiratory mechanics in anesthetized dogs

1986 ◽  
Vol 61 (5) ◽  
pp. 1647-1655 ◽  
Author(s):  
W. A. Zin ◽  
A. Boddener ◽  
P. R. Silva ◽  
T. M. Pinto ◽  
J. Milic-Emili
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Power Functions ◽  
Intrinsic Resistance ◽  
Pressure Losses ◽  
Inspiratory Muscles ◽  
Anesthetized Dogs ◽  
Force Velocity ◽  
Spontaneously Breathing ◽  
Active Impedance

In six spontaneously breathing anesthetized dogs (pentobarbital sodium, 30 mg/kg) airflow, volume, and tracheal and esophageal pressures were measured. The active and passive mechanical properties of the total respiratory system, lung, and chest wall were calculated. The average passive values of respiratory system, lung, and chest wall elastances amounted to, respectively, 50.1, 32.3, and 17.7 cmH2O X l-1. Resistive pressure-vs.-flow relationships for the relaxed respiratory system, lung, and chest wall were also determined; a linear relationship was found for the former (the total passive intrinsic resistance averaged 4.1 cmH2O X l-1 X s), whereas power functions best described the others: the pulmonary pressure-flow relationship exhibited an upward concavity, which for the chest wall presented an upward convexity. The average active elastance and resistance of the respiratory system were, respectively, 64.0 cmH2O X l-1 and 5.4 cmH2O X l-1 X s. The greater active impedance reflects pressure losses due to force-length and force-velocity properties of the inspiratory muscles and those due to distortion of the respiratory system from its relaxed configuration.

Sign in / Sign up

Export Citation Format

Share Document