INFLUENCE OF END-EXPIRATORY LUNG VOLUME ON CARBON DIOXIDE ELIMINATION DURING HIGH FREQUENCY VENTILATION IN DOGS

We tested the response of nine barbiturate-anesthetized dogs to high-frequency ventilation (HFV) (40-55 ml tidal volumes at 15 Hz) while measuring and controlling lung volume and blood gases. When lung volume and PCO2 were held constant, six of the nine responded to HFV by lengthening expiration. In each of these six dogs the maximal response was apnea. The response was immediate. In submaximal responses only expiration was changed; inspiratory time and peak diaphragmatic electrical activity were unaffected. There was a variable effect on abdominal muscle activity. If mean expiratory lung volume was allowed to increase at the onset of HFV, the Hering-Breuer inflation reflex added to the response. The strength of the response depended on level of anesthesia and arterial PO2. Vagotomy abolished the response in all cases. We conclude that oscillation of the respiratory system reflexly prolongs expiration via mechanoreceptors, perhaps those in the lungs.

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Effects of mean airway pressure on gas transport during high-frequency ventilation in dogs

Journal of Applied Physiology ◽

10.1152/jappl.1986.61.5.1896 ◽

1986 ◽

Vol 61 (5) ◽

pp. 1896-1902 ◽

Cited By ~ 5

Author(s):

Y. Yamada ◽

J. G. Venegas ◽

D. J. Strieder ◽

C. A. Hales

Keyword(s):

Lung Volume ◽

High Frequency ◽

Airway Pressure ◽

Gas Transport ◽

Blood Gases ◽

Co2 Production ◽

High Frequency Ventilation ◽

Mean Airway Pressure ◽

Arterial Blood ◽

Frequency Ventilation

In 10 anesthetized, paralyzed, supine dogs, arterial blood gases and CO2 production (VCO2) were measured after 10-min runs of high-frequency ventilation (HFV) at three levels of mean airway pressure (Paw) (0, 5, and 10 cmH2O). HFV was delivered at frequencies (f) of 3, 6, and 9 Hz with a ventilator that generated known tidal volumes (VT) independent of respiratory system impedance. At each f, VT was adjusted at Paw of 0 cmH2O to obtain a eucapnia. As Paw was increased to 5 and 10 cmH2O, arterial PCO2 (PaCO2) increased and arterial PO2 (PaO2) decreased monotonically and significantly. The effect of Paw on PaCO2 and PaO2 was the same at 3, 6, and 9 Hz. Alveolar ventilation (VA), calculated from VCO2 and PaCO2, significantly decreased by 22.7 +/- 2.6 and 40.1 +/- 2.6% after Paw was increased to 5 and 10 cmH2O, respectively. By taking into account the changes in anatomic dead space (VD) with lung volume, VA at different levels of Paw fits the gas transport relationship for HFV derived previously: VA = 0.13 (VT/VD)1.2 VTf (J. Appl. Physiol. 60: 1025–1030, 1986). We conclude that increasing Paw and lung volume significantly decreases gas transport during HFV and that this effect is due to the concomitant increase of the volume of conducting airways.

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Intermittent high frequency ventilation: a new mode to measure changes in lung volume and alveolar gas concentration, enhance CO2elimination and reduce intrapulmonary pressures

Acta Anaesthesiologica Scandinavica ◽

10.1111/j.1399-6576.1988.tb02732.x ◽

1988 ◽

Vol 32 (4) ◽

pp. 295-303 ◽

Cited By ~ 2

Author(s):

M. K. Chakrabarti ◽

G. O. Swenzen ◽

J. G. Whitwam

Keyword(s):

Lung Volume ◽

High Frequency ◽

High Frequency Ventilation ◽

Gas Concentration ◽

Frequency Ventilation

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Lung volume recruitment during high-frequency ventilation

The Journal of Pediatrics ◽

10.1016/s0022-3476(05)82907-5 ◽

1990 ◽

Vol 116 (2) ◽

pp. 317 ◽

Cited By ~ 2

Author(s):

A. Charles Bryan

Keyword(s):

Lung Volume ◽

High Frequency ◽

High Frequency Ventilation ◽

Frequency Ventilation ◽

Lung Volume Recruitment

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Regional distribution of chest wall displacements in infants during high-frequency ventilation

Journal of Applied Physiology ◽

10.1152/japplphysiol.01086.2018 ◽

2019 ◽

Vol 126 (4) ◽

pp. 928-933 ◽

Cited By ~ 1

Author(s):

Emanuela Zannin ◽

Maria Luisa Ventura ◽

Giulia Dognini ◽

Chiara Veneroni ◽

Jane J. Pillow ◽

...

Keyword(s):

Carbon Dioxide ◽

Diffusion Coefficient ◽

Phase Shift ◽

Gas Exchange ◽

Chest Wall ◽

High Frequency ◽

Regional Distribution ◽

High Frequency Ventilation ◽

Volume Changes ◽

Frequency Ventilation

The distribution of ventilation during high-frequency ventilation (HFV) is asynchronous, nonhomogeneous, and frequency dependent. We hypothesized that differences in the regional distribution of ventilation at different oscillatory frequencies may affect gas exchange efficiency. We studied 15 newborn infants with a median gestational age of 28.9 (26.4–30.3) wk and body weight of 1.0 (0.8–1.4) kg. Five ventilation frequencies (5, 8, 10, 12, and 15 Hz) were tested, keeping carbon dioxide diffusion coefficient constant. The displacements of 24 passive markers placed on the infant’s chest wall were measured by optoelectronic plethysmography. We evaluated the amplitude and phase shift of displacements of single markers placed along the midline and the regional displacements of the chest wall surface. Blood gases were unaffected by frequency. Chest wall volume changes decreased from 1.6 (0.4) ml/kg at 5 Hz to 0.7 ml/kg at 15 Hz. At all frequencies, the abdomen (AB) oscillated more markedly than the ribcage (RC). The mean (SD) AB/RC ratio was 1. 95 (0.7) at 5 Hz, increased to 2.1 (1.3) at 10 Hz, and then decreased to 1.1 (0.5) at 15 Hz ( P < 0.05 vs. 10 Hz). Volume changes in the AB lagged the RC and this phase shift increased with frequency. The AB oscillated more than the RC at all frequencies. Regional oscillations were highly inhomogeneous up to 10 Hz, and they became progressively more asynchronous with increasing frequency. When the carbon dioxide diffusion coefficient is held constant, such differences in regional chest wall expansion do not affect gas exchange. NEW & NOTEWORTHY We characterized the regional distribution of chest wall displacements in infants receiving high-frequency oscillatory ventilation at different frequencies. When carbon dioxide diffusion coefficient is held constant, there is no combination of frequency and tidal volume that optimizes gas exchange. The relative displacement between different chest wall compartments is not affected by frequency. However, at high frequencies, chest wall displacements are lower, with the potential to reduce total and regional overdistension without affecting gas exchange.

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