High-frequency ventilation in dogs with three gases of different densities

1991 ◽  
Vol 70 (5) ◽  
pp. 2188-2192 ◽  
Author(s):  
M. J. Jaeger
Keyword(s):  
Tidal Volume ◽  
High Frequency ◽  
Kinematic Viscosity ◽  
Blood Gases ◽  
High Frequency Oscillation ◽  
High Frequency Ventilation ◽  
Gas Mixture ◽  
Frequency Oscillation ◽  
Frequency Ventilation ◽  
Arterial Po2

Dogs were ventilated with a high-frequency oscillation device varying the frequency (5-15 Hz), the tidal volume (25-100 ml), and the resident gas (He, N2, SF6). Tidal volume was measured with a body plethysmograph. Blood gases were measured after a quasi-steady state was established. The kinematic viscosity of the breathing gas mixture, which changed by 1,700%, was found to have little effect on arterial PO2 and PCO2. The results are consistent with findings in a branched model that consisted of tubes with a diameter of 1 cm and with the theory of Taylor-type diffusion in turbulent flow. In addition, experiments were performed reducing and increasing the equipment dead space. This resulted in changes of PO2 and PCO2 that were appreciably less than those resulting from variations of tidal volume of the same magnitude.

A new system for ventilating with high-frequency oscillation

1982 ◽  
Vol 53 (6) ◽  
pp. 1638-1642 ◽  
Author(s):  
Y. K. Ngeow ◽  
W. Mitzner
Keyword(s):  
Tidal Volume ◽  
High Frequency ◽  
Airway Pressure ◽  
Ventilation System ◽  
High Frequency Oscillation ◽  
High Frequency Ventilation ◽  
Mean Airway Pressure ◽  
Frequency Oscillation ◽  
Frequency Ventilation ◽  
New System

We describe simple high-frequency oscillation systems that incorporate a CO2 absorber and supply O2 on a need basis. These systems have the advantage of easy control of mean airway pressure and airway hydration and negligible loss of oscillatory tidal volume. Experiments done at constant tidal volume showed that as frequency (and hence total ventilation) increased, arterial CO2 tension (PaCO2) decreased. The fall in PaCO2 occurred until frequency reached approximately 20 Hz; above 20 Hz further increases in frequency had little or no effect on PaCO2. Because of their practical advantages the techniques described here may be quite useful in a clinical setting where an oscillator, rather than jet-type high-frequency, ventilation system is desired.

High-frequency ventilation lengthens expiration in the anesthetized dog

1983 ◽  
Vol 55 (2) ◽  
pp. 329-334 ◽  
Author(s):  
R. Banzett ◽  
J. Lehr ◽  
B. Geffroy
Keyword(s):  
Lung Volume ◽  
High Frequency ◽  
Blood Gases ◽  
Abdominal Muscle ◽  
High Frequency Ventilation ◽  
Maximal Response ◽  
Variable Effect ◽  
Frequency Ventilation ◽  
Anesthetized Dogs ◽  
Arterial Po2

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.

Alveolar ventilation during high-frequency oscillation: core dead space concept

1984 ◽  
Vol 56 (3) ◽  
pp. 700-707 ◽  
Author(s):  
D. Isabey ◽  
A. Harf ◽  
H. K. Chang
Keyword(s):  
Tidal Volume ◽  
Dead Space ◽  
High Frequency ◽  
Alveolar Ventilation ◽  
High Frequency Oscillation ◽  
High Frequency Ventilation ◽  
Frequency Oscillation ◽  
Simple Physical Model ◽  
Small Tube ◽  
The Dead

To assess the role of direct alveolar ventilation during high-frequency ventilation, we studied convective gas mixing during high-frequency oscillation with tidal volumes close to the dead space volume in a simple physical model. A main conduit representing a large airway was connected with a rigid sphere (V = 77, 517, and 1,719 cm3) by a small circular tube (d = 0.3 and 0.5 cm; L = 5, 10, and 20 cm). The efficiency of sinusoidal oscillations (f = 5, 20, and 40 Hz) applied at one end of the main conduit was assessed from the washout of a CO2 mixture from the sphere; to flush CO2 from the main fluid line, a constant flow of air was used. The decay in CO2 concentration measured in the sphere was exponential and therefore characterized by a measured time constant (tau m). Taking the small tube volume as the ventilatory dead space (VD), an effective tidal volume (VT*) was computed from tau m and compared with the tidal volume (VT) obtained separately from the pressure variation in the sphere. The discrepancy between these two tidal volumes has been found to be uniquely dependent on the ratio VT/VD within the range of VT/VD studied (0.5–2.2). For VT/VD less than 1.2, VT* was larger than VT, indicating that the conventional concept of alveolar ventilation does not apply. From the partition of the oscillatory flow in the small tube into two regions, the core and the unsteady boundary layer, we theoretically computed the proportions of the sinusoidal flow (or tidal volume) and the dead space for each region.(ABSTRACT TRUNCATED AT 250 WORDS)

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

1986 ◽  
Vol 61 (5) ◽  
pp. 1896-1902 ◽  
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.

Tidal Volume and Frequency Dependence of Carbon Dioxide Elimination by High-Frequency Ventilation

1982 ◽  
Vol 26 (5) ◽  
pp. 277-278
Author(s):  
T. H. ROSSING ◽  
A. S. SLUTSKY ◽  
J. L. LEHR ◽  
P. A. DRINKER ◽  
R. KAMM ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Tidal Volume ◽  
Frequency Dependence ◽  
High Frequency ◽  
High Frequency Ventilation ◽  
Carbon Dioxide Elimination ◽  
Frequency Ventilation

scholarly journals 1826 TRANSTHORACIC IMPEDANCE AS A METHOD OF MEASURING TIDAL VOLUME DURING HIGH FREQUENCY VENTILATION

1985 ◽  
Vol 19 (4) ◽  
pp. 415A-415A
Author(s):  
Kenneth L Sandberg ◽  
Elizabeth P Krueger ◽  
Daniel P Lindstrom ◽  
Hakan Sundell ◽  
Robert B Cotton
Keyword(s):  
Tidal Volume ◽  
High Frequency ◽  
High Frequency Ventilation ◽  
Transthoracic Impedance ◽  
Frequency Ventilation

Physiological dead space during high-frequency ventilation in dogs

1984 ◽  
Vol 57 (3) ◽  
pp. 881-887 ◽  
Author(s):  
G. G. Weinmann ◽  
W. Mitzner ◽  
S. Permutt
Keyword(s):  
Gas Exchange ◽  
Tidal Volume ◽  
Dead Space ◽  
High Frequency ◽  
Minute Ventilation ◽  
Alveolar Ventilation ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Frequency Ventilation ◽  
Normal Ventilation

Tidal volumes used in high-frequency ventilation (HFV) may be smaller than anatomic dead space, but since gas exchange does take place, physiological dead space (VD) must be smaller than tidal volume (VT). We quantified changes in VD in three dogs at constant alveolar ventilation using the Bohr equation as VT was varied from 3 to 15 ml/kg and frequency (f) from 0.2 to 8 Hz, ranges that include normal as well as HFV. We found that VD was relatively constant at tidal volumes associated with normal ventilation (7–15 ml/kg) but fell sharply as VT was reduced further to tidal volumes associated with HFV (less than 7 ml/kg). The frequency required to maintain constant alveolar ventilation increased slowly as tidal volume was decreased from 15 to 7 ml/kg but rose sharply with attendant rapid increases in minute ventilation as tidal volumes were decreased to less than 7 ml/kg. At tidal volumes less than 7 ml/kg, the data deviated substantially from the conventional alveolar ventilation equation [f(VT - VD) = constant] but fit well a model derived previously for HFV. This model predicts that gas exchange with volumes smaller than dead space should vary approximately as the product of f and VT2.

scholarly journals Outcome of neonates receiving high frequency oscillation ventilation in a tertiary care institution

2019 ◽  
Vol 6 (3) ◽  
pp. 959
Author(s):  
Kalpana M. S. ◽  
Kalyani S.
Keyword(s):  
Respiratory Failure ◽  
High Frequency ◽  
Tertiary Care ◽  
Pulmonary Hemorrhage ◽  
Oxygenation Index ◽  
Lung Recruitment ◽  
High Frequency Oscillation ◽  
High Frequency Ventilation ◽  
Female Ratio ◽  
Frequency Ventilation

Background: High-frequency ventilation is defined as ventilation at a frequency greater than four times normal respiratory rate. HFOV has been used as alternative to conventional ventilation and in respiratory failure of various etiologies. The aim of the study was to identify the indications of neonates receiving HFOV, following failure of conventional ventilation.Methods: Total 93 neonates were enrolled in the study who received HFOV. The criteria for starting HFOV, the ventilator settings, CBG and ABG analysis, oxygenation index (OI), duration of ventilation and complications of ventilation were recorded during CMV and subsequently when shifted over to HFOV. Outcomes such as oxygenation, lung recruitment and ventilation and survival were monitored.Results: Total 66 neonates (71%) were term babies. Among the 27 preterm 18 (18.4%) were 33-34±6 weeks of gestational age. Male were 50 in number (53.8%) and female were 43 (46.2%). The male: female ratio was 50:43. Disease specific survival analysis revealed more than 50% survival in cases of pneumonia, collapse, air leak, MAS and pulmonary hemorrhage. 16 out of 33 babies (48.5%) with PPHN survived. All 3 babies with CDH expired. Of the 93 neonates included in the study, 53 (57%) of them were discharged home. The major complications noted while on HFOV were- 38 neonates (40.8%) had air leaks. Instead of, ventilator associated pneumonia was present in 42 of them (45.1%) and none of them developed IVH or NTB (Necrotising tracheo bronchitis).Conclusions: HFOV is a safe and effective technique in the treatment of neonates with respiratory failure in whom CMV fails. The results of present study show that rescue HFOV improved oxygenation, ventilation and lung recruitment and there was no increased incidence of IVH.

scholarly journals Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Ricardo Luiz Cordioli ◽  
Marcelo Park ◽  
Eduardo Leite Vieira Costa ◽  
Susimeire Gomes ◽  
Laurent Brochard ◽  
...  
Keyword(s):  
Tidal Volume ◽  
High Frequency ◽  
Airway Pressure ◽  
High Frequency Ventilation ◽  
Mean Airway Pressure ◽  
Frequency Ventilation

Effects of respiratory variables on regional gas transport during high-frequency ventilation

1988 ◽  
Vol 64 (5) ◽  
pp. 2108-2118 ◽  
Author(s):  
J. G. Venegas ◽  
Y. Yamada ◽  
J. Custer ◽  
C. A. Hales
Keyword(s):  
Tidal Volume ◽  
High Frequency ◽  
Transport Mechanism ◽  
Gas Transport ◽  
Substantial Effect ◽  
High Frequency Ventilation ◽  
Regional Effects ◽  
Functional Images ◽  
Tracer Isotope ◽  
Frequency Ventilation

The regional effects of tidal volume (VT), respiratory frequency, and expiratory-to-inspiratory time ratio (TE/TI) during high-frequency ventilation (HFV) were studied in anesthetized and paralyzed dogs. Regional ventilation per unit of lung volume (spVr) was assessed with a positron camera during the washout of the tracer isotope 13NN from the lungs of 12 supine dogs. From the washout data, functional images of the mean residence time (MRT) of 13NN were produced and spVr was estimated as the inverse of the regional MRT. We found that at a constant VT X f product (where f represents frequency), increasing VT resulted in higher overall lung spV through the local enhancement of the basal spVr and with little effect in the apical spVr. In contrast, increasing VT X f at constant VT increased overall ventilation without significantly affecting the distribution of spVr values. TE/TI had no substantial effect in regional spVr distribution. These findings suggest that the dependency of gas transport during HFV of the form VT2 X f is the result of a progressive regional transition in gas transport mechanism. It appears, therefore, that as VT increases, the gas transport mechanism changes from a relative inefficient dispersive mechanism, dependent on VT X f, to the more efficient mechanism of direct fresh gas convection to alveoli with high regional tidal volume-to-dead-space ratio. A mathematical model of gas transport in a nonhomogeneous lung that exhibits such behavior is presented.

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