Effect of changes in lung volume on respiratory system compliance in newborn infants

1989 ◽  
Vol 67 (3) ◽  
pp. 1192-1197 ◽  
Author(s):  
F. Ratjen ◽  
R. Zinman ◽  
A. R. Stark ◽  
L. E. Leszczynski ◽  
M. E. Wohl
Keyword(s):  
Tidal Volume ◽  
Respiratory System ◽  
Lung Volume ◽  
Newborn Infants ◽  
Face Mask ◽  
Flow Volume ◽  
Respiratory System Compliance ◽  
Tidal Breathing ◽  
Volume Changes ◽  
Passive Flow

Total respiratory system compliance (Crs) at volumes above the tidal volume (VT) was studied by use of the expiratory volume clamping (EVC) technique in 10 healthy sleeping unsedated newborn infants. Flow was measured with a pneumotachograph attached to a face mask and integrated to yield volume. Volume changes were confirmed by respiratory inductance plethysmography. Crs measured by EVC was compared with Crs during tidal breathing determined by the passive flow-volume (PFV) technique. Volume increases of approximately 75% VT were achieved with three to eight inspiratory efforts during expiratory occlusions. Crs above VT was consistently greater than during tidal breathing (P less than 0.0005). This increase in Crs likely reflects recruitment of lung units that are closed or atelectatic in the VT range. Within the VT range, Crs measured by PFV was compared with that obtained by the multiple-occlusion method (MO). PFV yielded greater values of Crs than MO (P less than 0.01). This may be due to braking of expiratory airflow after the release of an occlusion or nonlinearity of Crs. Thus both volume recruitment and airflow retardation may affect the measurement of Crs in unsedated newborn infants.

Thyroarytenoid muscle activity during hypoxia in awake lambs

1990 ◽  
Vol 69 (6) ◽  
pp. 1998-2003 ◽  
Author(s):  
J. P. Praud ◽  
E. Canet ◽  
D. Dalle ◽  
A. Bairam ◽  
M. Bureau
Keyword(s):  
Lung Volume ◽  
Muscle Activity ◽  
Early Life ◽  
Face Mask ◽  
Flow Volume ◽  
Adductor Muscles ◽  
Thyroarytenoid Muscle

It is generally accepted that hypoxia in early life results in active laryngeal braking of expiratory airflow via the recruitment of glottic adductor muscles. We examined the electromyogram expiratory activity of the thyroarytenoid muscle in seven 11- to 18-day-old awake nonsedated lambs exposed to an inspired O2 fraction of 0.08 for 18 min. The lambs breathed through a face mask and a pneumotachograph. During baseline prehypoxic breathing, the thyroarytenoid muscle was largely inactive in each awake lamb. Unexpectedly, no recruitment of the thyroarytenoid muscle was recorded during hypoxia in any of the seven lambs; simultaneous examination of the flow-volume curves revealed an absence of expiratory airflow braking. Also unexpectedly, marked expiratory activity of the thyroarytenoid muscle was recorded, with each expiration occurring within less than 10 s after the return to room air. The resulting delay of expiration was apparent in the flow-volume loops. Thus, in awake 11- to 18-day-old lambs, 1) active expiratory glottic adduction is absent during hypoxia and 2) a return from hypoxia to room air results in prolonged expiration as well as active glottic adduction that controls end-expiratory lung volume.

Volume of activation of the Hering-Breuer inflation reflex in the newborn infant

2001 ◽  
Vol 90 (3) ◽  
pp. 763-769 ◽  
Author(s):  
A. Hassan ◽  
J. Gossage ◽  
D. Ingram ◽  
S. Lee ◽  
A. D. Milner
Keyword(s):  
Lung Volume ◽  
Polynomial Regression ◽  
Neonatal Period ◽  
Face Mask ◽  
Progressive Increase ◽  
Inspiratory Time ◽  
Tidal Breathing ◽  
Expiratory Time ◽  
Healthy Infants ◽  
Residual Capacity

Although the Hering-Breuer inflation reflex (HBIR) is active within tidal breathing range in the neonatal period, there is no information regarding whether a critical volume has to be exceeded before any effect can be observed. To explore this, effects of multiple airway occlusions on inspiratory and expiratory timing were measured throughout tidal breathing range using a face mask and shutter system. In 20 of the 22 healthy infants studied, there was significant shortening of inspiration because the volume at which occlusion occurred rose from functional residual capacity (FRC) to end-inspiratory volume [14.9% reduction in inspiratory time (per ml/kg increase in lung volume at occlusion)]. All infants showed a significant increase in expiratory time [17.1% increase (per ml/kg increase in lung volume at occlusion)]. Polynomial regression analyses revealed a progressive increase in strength of HBIR from FRC to ∼4 ml/kg above FRC. Eighteen infants showed no further shortening of inspiratory time and 10 infants no further lengthening of expiratory time with increasing occlusion volumes, indicating maximal stimulation of the reflex had been achieved. There was a significant relationship between strength of HBIR and respiratory rate, suggesting that HBIR modifies the breathing pattern in the neonatal period.

Effect of hyperinflation on inspiratory function of the diaphragm

1976 ◽  
Vol 40 (1) ◽  
pp. 67-73 ◽  
Author(s):  
V. D. Minh ◽  
G. F. Dolan ◽  
R. F. Konopka ◽  
K. M. Moser
Keyword(s):  
Tidal Volume ◽  
Respiratory System ◽  
Lung Volume ◽  
Phrenic Nerve ◽  
Constant Stimulus ◽  
Functional Loss ◽  
Expiratory Muscle ◽  
Volume Relationship ◽  
Phrenic Stimulation

The inspiratory efficiency of the diaphragm during unilateral and bilateral phrenic stimulation (UEPS and BEPS) with constant stimulus was studied in seven dogs from FRC to 120% TLC. Alveolar pressures (PAl) were recorded during relaxation, BEPS and UEPS at each lung volume in the closed respiratory system. From the PAl-lung volume curves, tidal volume (VT), and pressure developed by the diaphragm (Pmus) were derived. Results are summarized below. a) Hyperinflation impaired the inspiratory efficiency of the diaphragm which behaved as an expiratory muscle beyond the lung volume of 103.7% TLC (Vinef). b) The diaphragm during UEPS became expiratory at the same Vinef as during (BEPS. C) The VT-lung volume relationship was linear during BEPS, allowing simple quantitation of VT loss with hyperinflation and prediction of Vinef. d) With only one phrenic nerve stimulated, the functional loss is less pronounced in VT than in Pmus, as compared to BEPS, indicating that the respiratory system was more compliant during UEPS than BEPS. This compliance difference from UEPS to BEPS diminished with severe hyperinflation.

Hypercapnia increases expiratory braking in preterm infants

1993 ◽  
Vol 75 (6) ◽  
pp. 2665-2670 ◽  
Author(s):  
E. C. Eichenwald ◽  
R. A. Ungarelli ◽  
A. R. Stark
Keyword(s):  
Tidal Volume ◽  
Premature Infants ◽  
Lung Volume ◽  
Newborn Infants ◽  
Emg Activity ◽  
Quiet Sleep ◽  
Activity Peak ◽  
Posterior Cricoarytenoid ◽  
Respiratory Muscle Activity ◽  
Ventilatory Response To Co2

In contrast to adults, newborn infants breathe from an elevated end-expiratory lung volume, determined by the interaction of airflow retardation (braking) by the diaphragm and larynx, and expiratory duration. To determine the effect of hypercapnia on this strategy, we examined changes in respiratory muscle activity and the ventilatory response to CO2 breathing in eight premature infants 33–34 wk gestational age in the first 3 postnatal days. We recorded tidal volume, airflow, and electromyograms (EMG) of the laryngeal abductor [posterior cricoarytenoid (PCA)], which abducts the vocal cords, and diaphragm during behaviorally determined quiet sleep in room air and during steady-state inhalation of 2% CO2 in air. As expected, tidal volume increased (P < 0.0005) without a change in inspiratory duration with hypercapnia. Unexpectedly, in all subjects, expiratory duration was longer during CO2 inhalation (P < 0.001), accompanied by marked changes in expiratory flow patterns consistent with increased expiratory braking. Diaphragm post-inspiratory EMG activity increased with hypercapnia (P < 0.005) with no change in baseline diaphragm or PCA EMG activity. Peak inspiratory EMG activity of the diaphragm and PCA increased with CO2 (10 and 37%, respectively; P < 0.05). We conclude that the mechanisms used to elevate end-expiratory lung volume are enhanced during hypercapnia in premature infants. This breathing strategy may be important in maintaining gas exchange in infants with lung disease.

Movement of the ribs in supine humans for small and large changes in lung volume

2021 ◽  
Author(s):  
Billy L. Luu ◽  
Rhys J. McDonald ◽  
Bart Bolsterlee ◽  
Martin E. Heroux ◽  
Jane E. Butler ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
Chronic Obstructive ◽  
Tidal Breathing ◽  
Obstructive Pulmonary Disease ◽  
Before And After ◽  
Residual Capacity ◽  
Joint Coordinate System ◽  
Healthy Participants ◽  
Bucket Handle

An object tracking algorithm was used on computed tomography (CT) images of the thorax from six healthy participants and nine participants with chronic obstructive pulmonary disease (COPD) to describe the movement of the ribs between the static lung volumes of functional residual capacity (FRC) and total lung capacity (TLC). The continuous motion of the ribs during tidal breathing was also described using four-dimensional CT datasets from seven participants with thoracic esophageal malignancies. Rib motion was defined relative to a local joint coordinate system where rotations about the axes that predominantly affected the anteroposterior and transverse diameters of the rib cage were referred to as pump-handle and bucket-handle movements, respectively. Between TLC and FRC, pump-handle movements were 1.8 times larger in healthy participants than in participants with COPD, in line with their 1.6 times larger inspiratory capacities. However, when rib motion was normalized to the change in lung volume, pump-handle movements were similar for healthy and COPD participant groups. We found no differences in bucket-handle movements between participant groups before and after normalization. Pump-handle movement was the dominant rib motion between FRC and TLC, on average four times greater than bucket-handle movement in healthy participants. For expiratory tidal volume, pump-handle movements were 20% smaller than bucket-handle movements. When normalized to tidal volume and compared to inspiratory capacity, pump-handle movements were smaller and bucket-handle movements were larger during tidal breathing. The findings suggest that the pump-handle and bucket-handle components of rib motion vary for small and large changes in lung volume.

Regulation of frequency and depth of breathing during expiratory threshold loading in cats

1975 ◽  
Vol 38 (5) ◽  
pp. 869-874 ◽  
Author(s):  
M. M. Grunstein ◽  
I. Wyszogrodski ◽  
J. Milic-Emili
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
The Other ◽  
Spontaneous Ventilation ◽  
Volume Changes ◽  
Phasic Component ◽  
Stretch Receptors ◽  
Pulmonary Stretch Receptors ◽  
The Absolute ◽  
Spontaneously Breathing

In six spontaneously breathing anesthetized cats, intermittently subjected to inspiratory elastic loads, we have studied the relationships between tidal volume (VT) and the durations of inspiration (Ti) and breath duration (Ttot) obtained during spontaneous ventilation from resting lung volume (FRCc) and from elevated end-expiratory levels. The latter was elevated by submerging the expiratory breathing line into a column of water, representing the addition of an expiratory threshold load (ETL). The VT vs. Ti relationships obtained at different end-expiratory levels were similar, indicating that during ETL the vagal mechanism regulating Ti responds only to lung volume changes above the new end-expiratory level and is independent of the absolute end-expiratory lung volume. Single vagal fiber recordings suggest that this effect on Ti control may be explained on the basis of adaptation occurring at the level of the pulmonary stretch receptors. The control of Ttot, on the other hand, was found to depend both on the Ti of the preceding breath (phasic component) and on a separate vagal mechanism specifically affecting the duration of expiration (Te) in response to changes in the absolute end-expiratory lung volume. The latter mechanism is functionally inoperative at FRCc.

Effects of mean airway pressure and tidal volume on lung and chest wall mechanics in the dog

1993 ◽  
Vol 74 (5) ◽  
pp. 2286-2293 ◽  
Author(s):  
G. M. Barnas ◽  
J. Sprung
Keyword(s):  
Mechanical Properties ◽  
Tidal Volume ◽  
Chest Wall ◽  
Respiratory System ◽  
Lung Volume ◽  
Airway Pressure ◽  
Dynamic Mechanical Properties ◽  
Mean Airway Pressure ◽  
Residual Capacity ◽  
Normal Mean

Dependencies of the dynamic mechanical properties of the respiratory system on mean airway pressure (Paw) and the effects of tidal volume (VT) are not completely clear. We measured resistance and dynamic elastance of the total respiratory system (Rrs and Ers), lungs (RL and EL), and chest wall (Rcw and Ecw) in six healthy anesthetized paralyzed dogs during sinusoidal volume oscillations at the trachea (50–300 ml; 0.4 Hz) delivered at mean Paw from -9 to +23 cmH2O. Changes in end-expiratory lung volume, estimated with inductance plethysmographic belts, showed a typical sigmoidal relationship to mean Paw. Each dog showed the same dependencies of mechanical properties on mean Paw and VT. All elastances and resistances were minimal between 5 and 10 cmH2O mean Paw. All elastances, Rrs, and RL increased greatly with decreasing Paw below 5 cmH2O. Ers and EL increased above 10 cmH2O. Ecw, Ers, Rcw, and Rrs decreased slightly with increasing VT, but RL and EL were independent of VT. We conclude that 1) respiratory system impedance is minimal at the normal mean lung volume of supine anesthetized paralyzed dogs; 2) the dependency of RL on lung volume above functional residual capacity is dependent on VT and respiratory frequency; and 3) chest wall, but not lung, mechanical behavior is nonlinear (i.e., VT dependent) at any given lung volume.

Reflex control of inspiratory duration in newborn infants

1986 ◽  
Vol 60 (6) ◽  
pp. 2007-2014 ◽  
Author(s):  
P. C. Kosch ◽  
P. W. Davenport ◽  
J. A. Wozniak ◽  
A. R. Stark
Keyword(s):  
Newborn Infants ◽  
Face Mask ◽  
Curvilinear Relationship ◽  
Flow Volume ◽  
Healthy Infants ◽  
Switch Mechanism ◽  
Respiratory Valve ◽  
Reflex Control ◽  
Resistive Loads ◽  
Manifold System

We applied graded resistive and elastic loads and total airway occlusions to single inspirations in six full-term healthy infants on days 2–3 of life to investigate the effect on neural and mechanical inspiratory duration (TI). The infants breathed through a face mask and pneumotachograph, and flow, volume, airway pressure, and diaphragm electromyogram (EMG) were recorded. Loads were applied to the inspiratory outlet of a two-way respiratory valve using a manifold system. Application of all loads resulted in inspired volumes decreased from control (P less than 0.001), and changes were progressive with increasing loads. TI measured from the pattern of the diaphragm EMG (TIEMG) was prolonged from control by application of all elastic and resistive loads and by total airway occlusions, resulting in a single curvilinear relationship between inspired volume and TIEMG that was independent of inspired volume trajectory. In contrast, when TI was measured from the pattern of airflow, the effect of loading on the mechanical time constant of the respiratory system resulted in different inspired volume-TI relationships for elastic and resistive loads. Mechanical and neural inspired volume and duration of the following unloaded inspiration were unchanged from control values. These findings indicate that neural inspiratory timing in infants depends on magnitude of phasic volume change during inspiration. They are consistent with the hypothesis that termination of inspiration is accomplished by an “off-switch” mechanism and that inspired volume determines the level of vagally mediated inspiratory inhibition to trigger this mechanism.

scholarly journals The effect of body mass and sex on the accuracy of respiratory magnetometers for measurement of end-expiratory lung volumes

2016 ◽  
Vol 121 (5) ◽  
pp. 1169-1177 ◽  
Author(s):  
Joanne Avraam ◽  
Rosie Bourke ◽  
John Trinder ◽  
Christian L. Nicholas ◽  
Danny Brazzale ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Body Mass ◽  
Lung Volume ◽  
Normal Weight ◽  
Volume Changes ◽  
Obstructive Sleep ◽  
Target Volumes ◽  
Healthy Obese ◽  
Magnetometer Calibration ◽  
Calibration Techniques

Respiratory magnetometers are increasingly being used in sleep studies to measure changes in end-expiratory lung volume (EELV), including in obese obstructive sleep apnea patients. Despite this, the accuracy of magnetometers has not been confirmed in obese patients nor compared between sexes. Thus we compared spirometer-measured and magnetometer-estimated lung volume and tidal volume changes during voluntary end-expiratory lung volume changes of 1.5, 1, and 0.5 l above and 0.5 l below functional respiratory capacity in supine normal-weight [body mass index (BMI) < 25 kg/m] and healthy obese (BMI > 30 kg/m) men and women. Two different magnetometer calibration techniques proposed by Banzett et al. [Banzett RB, Mahan ST, Garner DM, Brughera A, Loring SH. J Appl Physiol (1985) 79: 2169–2176, 1995] and Sackner et al. [Sackner MA, Watson H, Belsito AS, Feinerman D, Suarez M, Gonzalez G, Bizousky F, Krieger B. J Appl Physiol (1985) 66: 410–420, 1989] were assessed. Across all groups and target volumes, magnetometers overestimated spirometer-measured EELV by ~65 ml (<0.001) with no difference between techniques (0.07). The Banzett method overestimated the spirometer EELV change in normal-weight women for all target volumes except +0.5 l, whereas no differences between mass or sex groups were observed for the Sackner technique. The variability of breath-to-breath measures of EELV was significantly higher for obese compared with nonobese subjects and was higher for the Sackner than Banzett technique. On the other hand, for tidal volume, both calibration techniques underestimated spirometer measurements (<0.001), with the underestimation being more marked for the Banzett than Sackner technique (0.03), in obese than normal weight (<0.001) and in men than in women (0.003). These results indicate that both body mass and sex affect the accuracy of respiratory magnetometers in measuring EELV and tidal volume.

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