Pressure transmission across the respiratory system at raised lung volumes in infants

1994 ◽  
Vol 77 (2) ◽  
pp. 1015-1020 ◽  
Author(s):  
D. J. Turner ◽  
C. J. Lanteri ◽  
P. N. LeSouef ◽  
P. D. Sly
Keyword(s):  
Lung Volume ◽  
Dynamic Pressure ◽  
Esophageal Pressure ◽  
Tidal Range ◽  
Lung Volumes ◽  
Pressure Transmission ◽  
Airway Opening ◽  
Forced Expiratory Flow ◽  
End Tidal ◽  
Volume Range

Forced expiratory flow-volume (FEFV) curves can be generated from end-tidal inspiration in infants with use of an inflatable jacket. We have developed a technique to raise lung volume in the infant before generation of FEFV curves. Measurements of pressure transmission to the airway opening by use of static maneuvers have shown no change with increasing lung volume above end-tidal inspiration. The aim of this study was to determine, under dynamic conditions (i.e., during rapid thoracic compression), whether the efficiency of pressure transmission across the chest wall is altered by raising lung volume above the tidal range. Dynamic pressure transmission (Ptx,dyn) was measured in five infants (age 6–17 mo). Jacket pressure (Pj), esophageal pressure, and volume were measured throughout passive and FEFV curves at lung volumes set by 10, 15, and 20 cmH2O preset pressure. The group mean Ptx,dyn was 37 +/- 6% (SE) of Pj at end-tidal inspiration, and no change was seen with further increases in lung volume. However, a mean decrease in Ptx,dyn of 42% was evident throughout the tidal volume range (i.e., from end-tidal inspiration to end expiration). Isovolume static pressure transmission (Ptx,st) was measured in three of the five infants by inflation of the jacket in a stepwise manner with the airway closed. Measurements were made at end-tidal inspiration and lung volumes at 10, 15, and 20 cmH2O preset pressure. Resulting changes in Pj, esophageal pressure, and airway opening pressure were compared using linear regressions to determine Ptx,st.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of lung volume on forced expiratory flows during rapid thoracoabdominal compression in infants

1995 ◽  
Vol 78 (5) ◽  
pp. 1993-1997 ◽  
Author(s):  
J. Hammer ◽  
C. J. Newth
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Forced Expiration ◽  
Flow Volume ◽  
Older Children ◽  
Lung Volumes ◽  
Volume Segment ◽  
Forced Expiratory Flow ◽  
Residual Capacity ◽  
End Tidal

The rapid thoracoabdominal compression (RTC) technique is commonly used in pulmonary function laboratories to assess flow-volume relationships in infants unable to produce a voluntary forced expiration maneuver. This technique produces forced expiratory flows over only a small lung volume segment (i.e., tidal volume). It has been argued that the RTC technique should be modified to measure flow-volume relationships over a larger portion of the vital capacity range to imitate the voluntary maximal forced expiratory maneuver obtained in older children and adults. We examined the effect of volume history on forced expiratory flows by generating forced expiratory flow-volume curves by RTC from well-defined inspiratory volumes delineated by inspiratory pressures of 10, 20, 30, and 40 cmH2O down to residual volume (i.e., the reference volume) in seven intubated and anesthetized infants with normal lungs [age 8.0 +/- 2.0 (SE) mo, weight 6.7 +/- 0.6 kg]. We compared maximal expiratory flows at isovolume points (25 and 10% of forced vital capacity) and found no significant differences in maximal isovolume flow rates measured from the different lung volumes. We conclude that there is no obvious need to initiate RTC from higher lung volumes if the technique is used for flow comparisons. However, compared with measurements of maximal flows at functional residual capacity by RTC from end-tidal inspiration, the initiation of RTC from a defined and reproducible inspiratory level appears to decrease the intrasubject variability of the maximal expiratory flows at low lung volumes.

Esophageal pressure in infants at elevated lung volumes and positive airway pressure

1983 ◽  
Vol 55 (2) ◽  
pp. 377-382 ◽  
Author(s):  
C. S. Beardsmore ◽  
J. Stocks ◽  
M. Silverman
Keyword(s):  
Lung Volume ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Esophageal Pressure ◽  
Tidal Range ◽  
Whole Body ◽  
Injection Technique ◽  
Lung Volumes ◽  
Airway Occlusion ◽  
Pressure Changes

The measurement of esophageal pressure changes (delta Pes) under conditions of elevated lung volume or continuous positive airway pressure (CPAP) was investigated in a group of 17 infants by use of an esophageal balloon. Eleven of the infants were studied in a whole-body plethysmograph, and lung volume was increased by a volume injection technique. Reproducible measurements of lung volume in the plethysmograph showed that changes in mask pressure (delta Pm) were accurate during airway occlusion in 10 of the 11 infants. A progressive elevation of the ratio delta Pes/delta Pm during respiratory efforts against occlusion at lung volumes above the tidal range was observed in 8 of the 11 infants. In only one of these infants could the error have been in delta Pm measurement. Of seven infants (including one common to both studies) studied under CPAP, six also showed this effect, which occurred predominantly in very young or preterm infants. Changes in esophageal pressure in infancy, measured at high lung volumes or pressures, may not be representative of mean pleural pressure changes.

Breathing at low lung volumes and chest strapping: a comparison of lung mechanics

1981 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
N. J. Douglas ◽  
G. B. Drummond ◽  
M. F. Sudlow
Keyword(s):  
Lung Volume ◽  
Maximum Flow ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Lung Volumes ◽  
Flow Rates ◽  
Recoil Pressure ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

In six normal subjects forced expiratory flow rates increased progressively with increasing degrees of chest strapping. In nine normal subjects forced expiratory flow rates increased with the time spent breathing with expiratory reserve volume 0.5 liters above residual volume, the increase being significant by 30 s (P less than 0.01), and flow rates were still increasing at 2 min, the longest time the subjects could breathe at this lung volume. The increase in flow after low lung volume breathing (LLVB) was similar to that produced by strapping. The effect of LLVB was diminished by the inhalation of the atropinelike drug ipratropium. Quasistatic recoil pressures were higher following strapping and LLVB than on partial or maximal expiration, but the rise in recoil pressure was insufficient to account for all the observed increased in maximum flow. We suggest that the effects of chest strapping are due to LLVB and that both cause bronchodilatation.

Lung volume and pleural pressure in the anesthetized hamster

1979 ◽  
Vol 46 (5) ◽  
pp. 927-931 ◽  
Author(s):  
Y. L. Lai
Keyword(s):  
Lung Volume ◽  
Esophageal Pressure ◽  
Lung Compliance ◽  
Pleural Pressure ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Residual Capacity ◽  
Wall Compliance

Lung volumes and respiratory pressures were measured in anesthetized male hamsters weighing an average 117 g. In 16 supine animals functional residual capacity (FRC) determined by body plethysmograph was 1.12 +/- 0.23 (SD) ml (about 20% total lung capacity, TLC) slightly and significantly larger than the FRC measured by saline displacement, 1.01 +/- 0.15 ml. Similar results were found in six prone animals. Paralysis did not significantly alter supine FRC. Contrary to published reports, pleural pressure (Ppl) estimated from esophageal pressure was negative at FRC. The fact that lung volume decreased by 0.2 ml (about 4% TLC) when the chest was opened at FRC provided additional evidence of negative Ppl at FRC. No consistent changes in the lung pressure-volume curve were found after the chest was opened. Deflation chest wall compliance just above FRC was about twice lung compliance. The vital capacity and reserve volumes in this study agreed with values reported in the literature. However, absolute lung volumes (TLC, FRC, and residual volume) were lower by about 1.4 ml, possibly because of earlier overestimates of box FRC.

Collapsibility of the Upper Airway during Anesthesia with Isoflurane

2002 ◽  
Vol 97 (4) ◽  
pp. 786-793 ◽  
Author(s):  
Peter R. Eastwood ◽  
Irene Szollosi ◽  
Peter R. Platt ◽  
David R. Hillman
Keyword(s):  
Lung Volume ◽  
Critical Pressure ◽  
Upper Airway ◽  
Esophageal Pressure ◽  
Inspiratory Flow ◽  
Flow Limitation ◽  
Anesthetic Depth ◽  
Volume Collapse ◽  
End Tidal ◽  
Spontaneously Breathing

Background The unprotected upper airway tends to obstruct during general anesthesia, yet its mechanical properties have not been studied in detail during this condition. Methods To study its collapsibility, pressure-flow relationships of the upper airway were obtained at three levels of anesthesia (end-tidal isoflurane = 1.2%, 0.8%, and 0.4%) in 16 subjects while supine and spontaneously breathing on nasal continuous positive airway pressure. At each level of anesthesia, mask pressure was transiently reduced from a pressure sufficient to abolish inspiratory flow limitation (11.8 +/- 2.7 cm H(2)O) to pressures resulting in variable degrees of flow limitation. The relation between mask pressure and maximal inspiratory flow was determined, and the critical pressure at which the airway occluded was recorded. The site of collapse was determined from simultaneous measurements of nasopharyngeal, oropharyngeal, and hypopharyngeal and esophageal pressures. Results The airway remained hypotonic (minimal or absent intramuscular genioglossus electromyogram activity) throughout each study. During flow-limited breaths, inspiratory flow decreased linearly with decreasing mask pressure (r(2) = 0.86 +/- 0.17), consistent with Starling resistor behavior. At end-tidal isoflurane of 1.2%, critical pressure was 1.1 +/- 3.5 cm H O; at 0.4% it decreased to -0.2 +/- 3.6 cm H(2)O ( < 0.05), indicating decreased airway collapsibility. This decrease was associated with a decrease in end-expiratory esophageal pressure of 0.6 +/- 0.9 cm H(2)O ( < 0.05), suggesting an increased lung volume. Collapse occurred in the retropalatal region in 14 subjects and in the retrolingual region in 2 subjects, and did not change with anesthetic depth. Conclusions Isoflurane anesthesia is associated with decreased muscle activity and increased collapsibility of the upper airway. In this state it adopts the behavior of a Starling resistor. The decreased collapsibility observed with decreasing anesthetic depth was not a consequence of neuromuscular activity, which was unchanged. Rather, it may be related to increased lung volume and its effect on airway wall longitudinal tension. The predominant site of collapse is the soft palate.

Rib cage deformation during static inspiratory efforts

1979 ◽  
Vol 46 (6) ◽  
pp. 1071-1075 ◽  
Author(s):  
N. A. Saunders ◽  
S. M. Kreitzer ◽  
R. H. Ingram
Keyword(s):  
Lung Volume ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Esophageal Pressure ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Opposite Change ◽  
Accessory Muscles ◽  
Lateral Diameter

Patterns of rib cage (RC) deformation were studied in six normal subjects during moderate static inspiratory efforts such that esophageal pressure (Pes) as an index of transthoracic pressure fell to between -30 and -60 cmH2O during each maneuver. At lung volumes below 50% inspiratory capacity (IC), static inspiratory efforts deformed RC to a more elliptical shape; RC lateral diameter became smaller and RC lateral diameter became larger. However, at high lung volumes (greater than 50% IC) the opposite change in RC dimensions occurred despite similar changes in Pes, i.e., the RC became more circular. These differences in RC deformation did not appear to be a possive consequence of increased lung volume because the RC could be voluntarily deformed to a more circular shape at low lung volume when a) subjects performed static inspiratory efforts mainly with their intercostal and accessory muscles rather than their diaphragm as judged by a smaller change in transdiaphragmatic pressure for the same Pes; or b) subjects statically contracted their diaphragm with it held in a relatively flattened configuration as assessed by a large abdominal AP dimension. We suggest that deformation of the RC during static inspiratory efforts is not as predictable as has previously been suggested but depends on the pattern of contraction and configuration of the respiratory muscles.

Coordination of breathing and swallowing in human infants

1981 ◽  
Vol 50 (4) ◽  
pp. 851-858 ◽  
Author(s):  
S. L. Wilson ◽  
B. T. Thach ◽  
R. T. Brouillette ◽  
Y. K. Abu-Osba
Keyword(s):  
Esophageal Pressure ◽  
Simultaneous Recording ◽  
Inspiratory Effort ◽  
Airway Closure ◽  
Human Infants ◽  
Lung Volumes ◽  
Pharyngeal Pressure ◽  
Respiratory Airflow ◽  
Lower Lung ◽  
Airway Opening

Spontaneous nonfeeding swallows taken during wakefulness and sleep were identified in nine preterm infants by characteristic patterns in pharyngeal pressure, submental electromyogram, and respiratory airflow. Two hundred and seventeen swallows during ongoing respiration interrupted either inspiratory or expiratory airflow with airway closure for approximately 1 s. The duration of airway closure was independent of respiratory rate. A brief "swallow-breath" was associated with swallow onset in most instances. The respiratory nature of this movement was confirmed by simultaneous recording of a fall in pharyngeal or esophageal pressure and outward movement of the abdomen. Prolongation of the respiratory cycle was generally observed when a swallow interrupted ventilation at higher lung volumes, i.e., in late inspiration or early expiration. When the swallow interrupted ventilation at lower lung volume, i.e, in late expiration or early inspiration, the subsequent inspiratory effort was usually obstructed as it preceded airway opening at the end of the swallow synergism.

Flow limitation in normal infants: a new method for forced expiratory maneuvers from raised lung volumes

1996 ◽  
Vol 80 (6) ◽  
pp. 2019-2025 ◽  
Author(s):  
A. Feher ◽  
R. Castile ◽  
J. Kisling ◽  
C. Angelicchio ◽  
D. Filbrun ◽  
...  
Keyword(s):  
Lung Volume ◽  
Transpulmonary Pressure ◽  
Forced Expiration ◽  
Flow Limitation ◽  
Residual Volume ◽  
Flow Curves ◽  
Lung Volumes ◽  
Pressure Flow ◽  
Healthy Infants ◽  
Pressure Transmission

Forced expiratory maneuvers generated by rapid thoracic compression have been used to assess airway function in infants. It remains unclear whether flow limitation can be achieved in healthy infants because low pressure transmission across the chest wall and inspiratory effort may limit the maximum transpulmonary pressure developed during the maneuver. We have found that several rapid inflations to a lung volume set at an airway pressure of 30 cmH2O (V80) briefly inhibit respiratory effort and allow forced expiration to proceed from V80 to residual volume. We used a water-filled esophageal catheter to measure isovolume pressure-flow curves in seven healthy infants (3-88 mo). Forced vital capacity (FVC) was defined as the volume between V80 and residual volume. Pressure transmission between the compression jacket and the esophagus decreased with decreasing lung volume and averaged 60 and 37% at 50 and 75% of expired FVC, respectively. Subjects demonstrated plateaus in their isovolume pressure-flow curves at 50% of expired FVC and lower lung volumes. We conclude that this new methodology enables forced expiratory maneuvers to achieve flow limitation in healthy infants over at least the lower portion of their lung volume.

Acute effects of thixotropy conditioning of inspiratory muscles on end-expiratory chest wall and lung volumes in normal humans

2006 ◽  
Vol 101 (1) ◽  
pp. 298-306 ◽  
Author(s):  
Masahiko Izumizaki ◽  
Michiko Iwase ◽  
Yasuyoshi Ohshima ◽  
Ikuo Homma
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Human Subjects ◽  
Esophageal Pressure ◽  
Acute Effects ◽  
Lung Volumes ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Normal Human ◽  
Inflated Lung

Thixotropy conditioning of inspiratory muscles consisting of maximal inspiratory effort performed at an inflated lung volume is followed by an increase in end-expiratory position of the rib cage in normal human subjects. When performed at a deflated lung volume, conditioning is followed by a reduction in end-expiratory position. The present study was performed to determine whether changes in end-expiratory chest wall and lung volumes occur after thixotropy conditioning. We first examined the acute effects of conditioning on chest wall volume during subsequent five-breath cycles using respiratory inductive plethysmography ( n = 8). End-expiratory chest wall volume increased after conditioning at an inflated lung volume ( P < 0.05), which was attained mainly by rib cage movements. Conditioning at a deflated lung volume was followed by reductions in end-expiratory chest wall volume, which was explained by rib cage and abdominal volume changes ( P < 0.05). End-expiratory esophageal pressure decreased and increased after conditioning at inflated and deflated lung volumes, respectively ( n = 3). These changes in end-expiratory volumes and esophageal pressure were greatest for the first breath after conditioning. We also found that an increase in spirometrically determined inspiratory capacity ( n = 13) was maintained for 3 min after conditioning at a deflated lung volume, and a decrease for 1 min after conditioning at an inflated lung volume. Helium-dilution end-expiratory lung volume increased and decreased after conditioning at inflated and deflated lung volumes, respectively (both P < 0.05; n = 11). These results suggest that thixotropy conditioning changes end-expiratory volume of the chest wall and lung in normal human subjects.

Lung Volumes and Their Significance for Pharyngeal and Esophageal Swallowing Function

2014 ◽  
Vol 23 (3) ◽  
pp. 91-99 ◽  
Author(s):  
Roxann Diez Gross
Keyword(s):  
Lung Volume ◽  
Airway Pressure ◽  
Esophageal Pressure ◽  
Swallowing Function ◽  
Lung Volumes ◽  
Bolus Transit ◽  
Chest Wall Compliance ◽  
Subglottic Air Pressure ◽  
Pharyngeal Swallow ◽  
Wall Compliance

Subglottic airway pressure is generated during each swallow and this supports the probability that subglottic mechanoreceptors function as part of the overall afferent collage of signals that guide motor output. Lung volume at swallow onset, lung recoil forces, and chest wall compliance are all important factors that combine for the generation of sufficiently positive subglottic air pressure during the pharyngeal swallow. Higher lung volumes at swallow onset may also be advantageous to the esophageal pressure gradient during esophageal bolus transit. Patients with impaired lung-thoracic unit recoil and disordered breathing/swallowing patterns may not only benefit from learning to swallow during early exhalation, but may also need to start at a higher lung volume in order to compensate for reduced recoil effects on swallowing function.

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