Ventilatory capacity at altitude and its relation to mask design

1954 ◽  
Vol 143 (910) ◽  
pp. 32-39 ◽  
Keyword(s):  
Flow Resistance ◽  
Work Of Breathing ◽  
Normal Subjects ◽  
Gas Density ◽  
Low Resistance ◽  
Oxygen Mask ◽  
Mask Design ◽  
Ventilatory Capacity

It is shown that the ventilatory capacity of normal subjects increases on ascent to altitude. The increase is related to the decrease in lung-gas density and is compatible with the hypothesis that the work of maximum breathing remains constant at altitude (using the formula for the work of breathing developed by Otis, Fenn and Rahn). An oxygen mask designed for climbers using their full ventilatory capacity is described and its flow resistance compared with that of a low resistance apparatus for measuring a subject’s maximum voluntary ventilation.

Effect of alterations in end-tidal CO2 tension on flow resistance

1964 ◽  
Vol 19 (4) ◽  
pp. 745-749 ◽  
Author(s):  
Michael T. Newhouse ◽  
Margaret R. Becklake ◽  
Peter T. Macklem ◽  
Maurice McGregor
Keyword(s):  
Flow Resistance ◽  
Work Of Breathing ◽  
Normal Subjects ◽  
Minute Volume ◽  
Oxygen Cost ◽  
Voluntary Hyperventilation ◽  
Consistent Increase ◽  
The Mean ◽  
End Tidal ◽  
End Tidal Co2

The effect of PaCOCO2 on flow resistance and on the mechanical work of ventilating the lung was studied in five normal subjects during sustained voluntary hyperventilation. Hypocapnia caused a consistent increase in flow resistance. Thus, for a minute volume of approximately 30 liters/ min the mean inspiratory flow resistance was 133% greater and the mean respiratory work of ventilating the lungs 68% greater at PaCOCO2 20–25 mm Hg compared to values at 45–50 mm Hg. End-expiratory pressure and compliance were unaffected. Atropine and isoproterenol each markedly diminished the responsiveness of the airways to low PaCOCO2 levels and, given together, blocked the effect completely. These findings could largely account for the increase in oxygen cost of breathing, and in cardiac output associated with voluntary (i.e., hypocapneic) hyperventilation. PaCOCO2; work of breathing; mechanical properties Submitted on June 24, 1963

Respiratory Muscle Conditioning and the Work of Breathing: A Critical Balance in the Weaning Patient

1991 ◽  
Vol 2 (3) ◽  
pp. 405-414 ◽  
Author(s):  
Maureen E. Shekleton
Keyword(s):  
Respiratory Muscle ◽  
Work Of Breathing ◽  
Critical Role ◽  
Respiratory Muscles ◽  
Clinical Intervention ◽  
Ventilatory Function ◽  
Muscle Conditioning ◽  
Ventilatory Capacity ◽  
Demand And Capacity ◽  
Research Show

Normal ventilatory function depends on a balance between ventilatory demand and ventilatory capacity. The respiratory muscles play a critical role in achieving this balance. For patients experiencing ventilatory dysfunction, interventions that improve respiratory muscle function and therefore increase ventilatory capacity may be one way of restoring the balance and promoting ventilatory function. Respiratory muscle conditioning, or training the muscles to improve their strength and endurance, may be a useful clinical intervention in the weaning patient. Results of research show that muscle training may increase the ability of some patients to resume spontaneous ventilation. Continued research is needed to identify the appropriate training protocols for patients experiencing an acute imbalance between ventilatory demand and capacity

Analysis of the Facial Anthropometric Data of Korean Pilots for Oxygen Mask Design

2012 ◽  
Vol 56 (1) ◽  
pp. 1927-1931 ◽  
Author(s):  
Wonsup Lee ◽  
Jangwoon Park ◽  
Jeongrim Jeong ◽  
Eunjin Jeon ◽  
Hee-Eun Kim ◽  
...  
Keyword(s):  
Anthropometric Data ◽  
Oxygen Mask ◽  
Mask Design

Partitioning of work of breathing in mechanically ventilated COPD patients

1993 ◽  
Vol 75 (4) ◽  
pp. 1711-1719 ◽  
Author(s):  
M. L. Coussa ◽  
C. Guerin ◽  
N. T. Eissa ◽  
C. Corbeil ◽  
M. Chasse ◽  
...  
Keyword(s):  
Work Of Breathing ◽  
Normal Subjects ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Mechanically Ventilated ◽  
Airway Occlusion ◽  
Copd Patients ◽  
Additional Resistance ◽  
Work Done ◽  
Inspiratory Muscle Fatigue

In 10 sedated paralyzed mechanically ventilated chronic obstructive pulmonary disease (COPD) patients, we measured the inspiratory mechanical work done per breath on the respiratory system (WI,rs). We measured the tracheal and esophageal pressures to assess the lung (L) and chest wall (W) components of WI and used the technique of rapid airway occlusion during constant-flow inflation to partition WI into static work [Wst, including work due to intrinsic positive end-expiratory pressure (WPEEPi)], dynamic work due to airway resistance, and the additional resistance offered by the respiratory tissues. Although the patients were hyperinflated, the slope of the static volume-pressure relationships of the lung did not decrease with inflation volume up to 0.8 liter. WI,W was similar in COPD patients and normal subjects. All components of WI,L were higher in COPD patients. The increase in Wst,rs was due entirely to WPEEPi. Our data suggest that, during spontaneous breathing, COPD patients would probably develop inspiratory muscle fatigue, unless continuous positive airway pressure were applied to reduce WPEEPi.

scholarly journals Basic principles of neonatal bubble CPAP: effects on CPAP delivery and imposed work of breathing when altering the original design

2020 ◽  
Vol 105 (5) ◽  
pp. 550-554
Author(s):  
Sonja Baldursdottir ◽  
Markus Falk ◽  
Snorri Donaldsson ◽  
Baldvin Jonsson ◽  
Thomas Drevhammar
Keyword(s):  
High Resistance ◽  
Low Income ◽  
Dead Space ◽  
Airway Pressure ◽  
Work Of Breathing ◽  
Lung Model ◽  
Original Design ◽  
Middle Income ◽  
Low Resistance ◽  
Mechanical Lung

BackgroundThe original bubble continuous positive airway pressure (bCPAP) design has wide-bore tubing and a low-resistance interface. This creates a stable airway pressure that is reflected by the submersion depth of the expiratory tubing. Several systems with alterations to the original bCPAP design are now available. Most of these are aimed for use in low-income and middle-income countries and have not been compared with the original design.ObjectiveWe identified three major alterations to the original bCPAP design: (1) resistance of nasal interface, (2) volume of dead space and (3) diameter of expiratory tubing. Our aim was to study the effect of these alterations on CPAP delivery and work of breathing in a mechanical lung model. Dead space should always be avoided and was not further tested.MethodsThe effect of nasal interface resistance and expiratory tubing diameter was evaluated with simulated breathing in a mechanical lung model without interface leakage. The main outcome was delivered CPAP and imposed work of breathing.ResultsHigh-resistance interfaces and narrow expiratory tubing increased the work of breathing. Additionally, narrow expiratory tubing resulted in higher CPAP levels than indicated by the submersion depth.ConclusionOur study shows the significant effect on CPAP delivery and imposed work of breathing when using high-resistance interfaces and narrow expiratory tubing in bCPAP systems. New systems should include low-resistance interfaces and wide-bore tubing and be compared with the original bCPAP. Referring to all systems that bubble as bCPAP is misleading and potentially hazardous.

Distribution of inspired gas during ventilation without respiratory movements

1965 ◽  
Vol 20 (6) ◽  
pp. 1350-1354
Author(s):  
Stefan J. A. Lichtneckert ◽  
Claes E. G. Lundgren
Keyword(s):  
Flow Resistance ◽  
Airway Resistance ◽  
Artificial Respiration ◽  
Resistance Index ◽  
Normal Subjects ◽  
Alveolar Ventilation ◽  
Main Factors ◽  
Nitrogen Elimination ◽  
Respiratory Movements ◽  
Different Parts

Normal subjects were ventilated by means of a barospirator, which allows cyclical ventilation without respiratory movements. It was thus possible to eliminate the influence that distension may have and allow flow resistance in the airways and the volume of the air spaces ventilated through them to become the main factors defining the distribution of inspired gas. Distribution of inspired gas was measured by nitrogen-elimination technique and by calculation of the index of alveolar ventilation. It could be demonstrated that the distribution of inspired gas in ventilation without respiratory movements is uneven, which is asscribed to different relations between the above-mentioned resistance volume factors in different parts of the lungs. airway resistance; index of alveolar ventilation; barospirator ventilation; mechanics of breathing; lung function; nitrogen-elimination curves; artificial respiration Submitted on December 31, 1964

Extrathoracic airway resistance in man

1961 ◽  
Vol 16 (2) ◽  
pp. 326-330 ◽  
Author(s):  
Robert E. Hyatt ◽  
Roger E. Wilcox
Keyword(s):  
Flow Resistance ◽  
Airway Resistance ◽  
Human Subjects ◽  
Upper Airway ◽  
Normal Subjects ◽  
Mouth Breathing ◽  
Human Beings ◽  
Lung Inflation ◽  
Upper Airway Resistance ◽  
Extrathoracic Airway

Simultaneous extrathoracic and intrathoracic flow resistance was measured in 19 unanesthetized subjects during mouth breathing. Lateral intratracheal pressure was recorded from a needle introduced 2 cm below the larynx. The intratracheal-oral pressure gradient was recorded during various respiratory maneuvers. The pressure drop from esophagus to trachea was also recorded. The extrathoracic pressure-flow relationships were alinear. Large inter- and intrasubject variability in upper airway resistance was encountered. Some factors contributing to this variability were defined. The upper airway accounted for approximately 45% of the total airway resistance in nine normal and 20% in 10 emphysematous human subjects. Upper airway resistance decreased with increasing lung inflation in four normal subjects. The magnitude and potential variability of the upper airway resistance must be considered in evaluating maneuvers designed to alter intrathoracic flow resistance, especially in normal human beings. It appears that during mouth breathing the major component of the upper airway resistance is located in the larynx. Submitted on September 14, 1960

scholarly journals An annual cycle in the ventilatory capacity of men with pneumoconiosis and of normal subjects

Thorax ◽  
1968 ◽  
Vol 23 (4) ◽  
pp. 340-349 ◽  
Author(s):  
C. B. McKerrow ◽  
C. E. Rossiter
Keyword(s):  
Annual Cycle ◽  
Normal Subjects ◽  
Ventilatory Capacity
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