Effect of mean airway pressure on gas exchange during high-frequency oscillatory ventilation

Boynton, Bruce R.; Villanueva, Dina; Hammond, Michael D.; Vreeland, Patricia N.; Buckley, B. G.; Frantz, rd I. D.

doi:10.1152/jappl.1991.70.2.701

Cited by 22 publications

(10 citation statements)

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“…Kolton et al (12) and Lachmann et al (15) demonstrated that FRC decreases after lavage. We have previously shown that increasing lung volume in lavaged rabbits decreases venous admixture and improves oxygenation (14). Healthy and lavaged rabbits may not have differed with respect to effects of Haw because 5 cm H20, the lowest value studied, may have exceeded closing pressure for the lavaged animals, or because the inflation maneuver between changes of settings may have transiently eliminated differences in lung volume.…”

Section: Frequency (Hz)mentioning

confidence: 93%

“…Our resgts suggest that the combined effect of a V, of 2 mL/kg and a Pa, greater than or equal to 10 cm H 2 0 arc necessary to produce adequate oxygenation. We assume that Pa, improved oxygenation by increasing lung volume and decreasing venous admixture (14). The suboptimal oxygenation that occurs at lower frequencies for a V, of 1 mL/kg and Pa, of 5 cm H 2 0 (Figs.…”

Section: Frequency (Hz)mentioning

confidence: 99%

“…Allen et al (10) reported that the ratio, Pa,,/P,,, increased as &, increased near the resonant frequency in excised rabbit lungs. Although increasing Paw has not been shown to improve gas exchange in healthy animals (1 1) it does improve oxygenation in lung damaged animal models (12)(13)(14).We wished to determine whether there is a combination of frequency, V, and &, that provides adequate blood gas tensions (i.e. the highest Pao2 and a Pac02 between 35 and 55 tom) and minimizes airway pressure amplitude.…”

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confidence: 99%

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Frequency, Tidal Volume, and Mean Airway Pressure Combinations that Provide Adequate Gas Exchange and Low Alveolar Pressure during High Frequency Oscillatory Ventilation in Rabbits

et al. 1990

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ABSTRACT. We studied healthy and saline lavaged rabbits during high frequency oscillatory ventilation to determine what combination of frequency (0, tidal volume (V,), and mean airway pressure (Fa,) produced the lowest peakto-peak alveolar pressure amplitude (Pal,) and physiologic blood gas tensions. Sinusoidal volume changes were delivered through a tracheostomy by a piston pump driven by a linear motor. Tracheal pressure amplitude (P,,) was measured through a tracheal catheter and alveolar pressure amplitude was measured in a capsule glued to the right lower lobe. Paoz, Pacoz, P,,, and Pa,, were measured at the following settings: Fi02 = 0.5, frequency 2-28 Hz, V, 1-3 mL/kg (50 150% dead space) and Paw 5-15 cm H20. Many combinations of frequency and V, resulted in the same Pa02 and Paco2. Paw had a large effect on Pal, and minimal effect on blood gas tensions. In lavaged rabbits, the composite variable f X V : described the trends in Pa,, and blood gas tensions. As the product of f x V : increased, Paoz initially increased and then decreased, whereas Pacoz decreased and Pal,increased. No single combination of frequency, V, and Paw simultaneously provided the lowest Pal, and physiologic blood gas tensions. Adequate blood gas tensions and low Pa,, were o b t a i~d at frequencies less than 12 Hz, a V, of 2 mL/kg and a Pa, of 10 cm HzO. In healthy and lavaged rabbits Pao2 increased and Paco2 decreased as frequency increased at lower V,.Pao2 decreased as frequency increased at higher V, in lavaged rabbits only. Pa,, tended to be greater in lavaged rabbits. (Pediatr Res 27: 64-69,1990) Abbreviations f, frequency V,, tidal volume -Paw, mean airway pressure P,,, peak-to-peak tracheal pressure amplitude Selected effects off, V,, and paw on gas exchange and pressure amplitude have been studied previously in healthy and lung damaged animal models during HFOV. Oxygenation and ventilation have been shown to depend on frequency and V, (1, 2). Previous work indicating there is a relationship between C 0 2 elimination and the product of oscillatory frequency and Vt [VC02 = a(Qb(V,)" where a, b, c are constants] (3, 4) led us to evaluate the relationship of arterial blood gas tensions to the product f x V? (5). We observed that many combinations of frequency and V, produced equivalent blood gas tensions and that the composite variable f x V : was a good descriptor of our mean arterial blood gas tensions during HFOV in healthy rabbits. Others have found that different combinations of frequency, V, and Paw can produce equivalent blood gas tensions (3, 4) but the resultant pressure swings in the trachea and alveolus may not be equivalent. Near the resonant frequency of the respiratory system, pressure swings in the alveolus may exceed those at the airway opening during HFOV (8, 9). Allen et al. (10) reported that the ratio, Pa,,/P,,, increased as &, increased near the resonant frequency in excised rabbit lungs. Although increasing Paw has not been shown to improve gas exchange in healthy animals (1 1) it does improve oxygenat...

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Section: Frequency (Hz)mentioning

confidence: 93%

Section: Frequency (Hz)mentioning

confidence: 99%

mentioning

confidence: 99%

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Frequency, Tidal Volume, and Mean Airway Pressure Combinations that Provide Adequate Gas Exchange and Low Alveolar Pressure during High Frequency Oscillatory Ventilation in Rabbits

et al. 1990

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“…From a physiological standpoint it is unlikely that the control of ventilation and oxygenation are truly independent from each other during HFOV [11][12][13]. Changes in functional residual capacity (FRC) during a recruitment procedure will almost certainly impact on lung compliance and oscillation volume (Vosc), as the position of ventilation changes along the inflation and deflation limbs of the pressure-volume curve [12][13][14][15].…”

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confidence: 99%

The effect of airway pressure and oscillation amplitude on ventilation in pre-term infants

Miedema

Jongh

Frerichs³

et al. 2012

Eur Respir J

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We determined the effect of lung recruitment and oscillation amplitude on regional oscillation volume and functional residual capacity (FRC) in high-frequency oscillatory ventilation (HFOV) used in pre-term infants with respiratory distress syndrome (RDS).Changes in lung volume, oscillation volume and carbon dioxide levels were recorded in 10 infants during a stepwise recruitment procedure, and an increase in pressure amplitude of 5 cmH 2 O was measured using electrical impedance tomography and transcutaneous monitoring. The pressures at maximal respiratory system compliance, maximal oscillation volume and minimal carbon dioxide levels were determined. Impedance data were analysed for the chest cross-section and predefined regions of interest.Despite the fixed pressure amplitude, the oscillation volume changed during the incremental pressure steps following a parabolic pattern, with an inverse relationship to the carbon dioxide pressures. The pressures corresponding with maximal compliance, maximal oscillation volume and minimal carbon dioxide were similar and highly correlated. Regional analysis showed similar findings. The increase in pressure amplitude resulted in increased oscillation volumes and decreased carbon dioxide levels, while FRC remained unchanged.In HFV pre-term infants with RDS, oscillation volumes are closely related to the position of ventilation in the pressure-volume envelope and the applied pressure amplitude. Changes in pressure amplitude do not seem to affect FRC.

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“…22,[53][54][55][56][57][58][59] By doing so, less CDP is needed to maintain a certain lung volume on the inflation limb, because of the hysteresis of the respiratory system. In our view and practice, this can be achieved in clinical practice in patients with DAD by initially setting the CDP 3-5 cm H 2 O above the mean airway pressure on conventional mechanical ventilation, as the distal CDP is lower than the set proximal CDP.…”

Section: Best Hfov Approach and Oscillator Settings For Oxygenationmentioning

confidence: 99%

Reflections on Pediatric High-Frequency Oscillatory Ventilation From a Physiologic Perspective

2012

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Mechanical ventilation using low tidal volumes has become universally accepted to prevent ventilator-induced lung injury. High-frequency oscillatory ventilation (HFOV) allows pulmonary gas exchange using very small tidal volume (1-2 mL/kg) with concomitant decreased risk of atelectrauma. However, its use in pediatric critical care varies between only 3% and 30% of all ventilated children. This might be explained by the fact that the beneficial effect of HFOV on patient outcome has not been ascertained. Alternatively, in contrast with present recommendations, one can ask if HFOV has been employed in its most optimal fashion related especially to the indications for and timing of HFOV, as well as to using the best oscillator settings. The first was addressed in one small randomized study showing that early use of HFOV, instead of rescue use, was associated with improved survival. From a physiologic perspective, the oscillator settings could be refined. Lung volume is the main determinant of oxygenation in diffuse alveolar disease, suggesting using an open-lung strategy by recruitment maneuvers, although this is in practice not custom. Using such an approach, the patient can be oscillated on the deflation limb of the pressurevolume (P-V) curve, allowing less pressure required to maintain a certain amount of lung volume. Gas exchange is determined by the frequency and the oscillatory power setting, controlling the magnitude of the membrane displacement. Experimental work as well as preliminary human data have shown that it is possible to achieve the smallest tidal volume with concomitant adequate gas exchange when oscillating at high frequency and high fixed power setting. Future studies are needed to validate these novel approaches and to evaluate their effect on patient outcome.

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Effect of mean airway pressure on gas exchange during high-frequency oscillatory ventilation

Cited by 22 publications

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Frequency, Tidal Volume, and Mean Airway Pressure Combinations that Provide Adequate Gas Exchange and Low Alveolar Pressure during High Frequency Oscillatory Ventilation in Rabbits

Frequency, Tidal Volume, and Mean Airway Pressure Combinations that Provide Adequate Gas Exchange and Low Alveolar Pressure during High Frequency Oscillatory Ventilation in Rabbits

The effect of airway pressure and oscillation amplitude on ventilation in pre-term infants

Reflections on Pediatric High-Frequency Oscillatory Ventilation From a Physiologic Perspective

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