High-frequency ventilation and oscillation

2016 ◽  
Author(s):  
Mireia Cuartero ◽  
Niall D. Ferguson
Keyword(s):  
High Frequency ◽  
Rescue Therapy ◽  
Conventional Mechanical Ventilation ◽  
High Frequency Ventilation ◽  
Ventilatory Strategy ◽  
Severe Hypoxaemia ◽  
Dead Space Volume ◽  
Frequency Ventilation ◽  
Ventilation Strategies ◽  
Physiological Values

High-frequency oscillatory ventilation (HFOV) is a key member of the family of modes called high-frequency ventilation and achieves adequate alveolar ventilation despite using very low tidal volumes, often below the dead space volume, at frequencies significantly above normal physiological values. It has been proposed as a potential protective ventilatory strategy, delivering minimal alveolar tidal stretch, while also providing continuous lung recruitment. HFOV has been successfully used in neonatal and paediatric intensive care units over the last 25 years. Since the late 1990s adults with acute respiratory distress syndrome have been treated using HFOV. In adults, several observational studies have shown improved oxygenation in patients with refractory hypoxaemia when HFOV was used as rescue therapy. Several small older trials had also suggested a mortality benefit with HFOV, but two recent randomized control trials in adults with ARDS have shed new light on this area. These trials not show benefit, and in one of them a suggestion of harm was seen with increased mortality for HFOV compared with protective conventional mechanical ventilation strategies (tidal volume target 6 mL/kg with higher positive end-expiratory pressure). While these findings do not necessarily apply to patients with severe hypoxaemia failing conventional ventilation, they increase uncertainty about the role of HFOV even in these patients.

Gas transport during high-frequency ventilation

1983 ◽  
Vol 55 (2) ◽  
pp. 472-478 ◽  
Author(s):  
V. Brusasco ◽  
T. J. Knopp ◽  
K. Rehder
Keyword(s):  
Stroke Volume ◽  
Dead Space ◽  
High Frequency ◽  
Oscillation Frequency ◽  
High Frequency Ventilation ◽  
Dead Space Volume ◽  
Entire Lung ◽  
Frequency Ventilation ◽  
Gas Volume ◽  
Space Volume

During high-frequency small-volume ventilation (HFV), the transport rate of gas from the mouth to a lung region is a function of two conductances (conductance is the transfer rate of a gas divided by its partial pressure difference): regional longitudinal gas conductance along the airways (Grlongi) and gas conductance between lung regions (Ginter). Grlongi per unit regional lung (gas) volume [Grlongi/(Vr beta g)] was determined during HFV in 11 anesthetized paralyzed dogs lying supine. The distribution of Grlongi/(Vr beta g) was nearly uniform during HFV when stroke volumes were less than approximately two-thirds of the Fowler dead-space volume. By contrast, the distribution of Grlongi/(Vr beta g) was nonuniform when the stroke volume exceeded approximately two-thirds of the Fowler dead-space volume and the oscillation frequency was 5 Hz. Gas conductance along the airways per unit lung gas volume [average Glongi/(V beta g)], for the entire lung, increased with stroke volume at all frequencies, but for a given product of oscillation frequency and stroke volume, the average Glongi/(V beta g) was greater when stroke volume was large and oscillation frequency was low. The average Glongi/(V beta g) increased with frequency up to a maximal value; the frequency at which the maximum occurred depended on the kinematic viscosity of the inspired gas mixture.

Pulmonary Mechanics in Preterm Neonates With Respiratory Failure Treated With High-Frequency Oscillatory Ventilation Compared With Conventional Mechanical Ventilation

PEDIATRICS ◽  
1991 ◽  
Vol 87 (4) ◽  
pp. 487-493
Author(s):  
Soraya Abbasi ◽  
Vinod K. Bhutani ◽  
Alan R. Spitzer ◽  
William W. Fox
Keyword(s):  
Mechanical Ventilation ◽  
Bronchopulmonary Dysplasia ◽  
High Frequency ◽  
Conventional Mechanical Ventilation ◽  
High Frequency Oscillatory Ventilation ◽  
Preterm Neonates ◽  
High Frequency Ventilation ◽  
Pulmonary Mechanics ◽  
Frequency Ventilation ◽  
High Frequency Oscillatory

Pulmonary mechanics were measured in 43 preterm neonates (mean ± SD values of birth weight 1.2 ± 0.3 kg, gestational age 30 ± 2 weeks) with respiratory failure who were concurrently randomly assigned to receive conventional mechanical ventilation (n = 22) or high-frequency ventilation (n = 21). The incidence of bronchopulmonary dysplasia was comparable in the two groups (high-frequency ventilation 57%, conventional ventilation 50%). Pulmonary functions were determined at 0.5, 1.0, 2.0, and 4.0 weeks postnatal ages. Data were collected while subjects were in a nonsedated state during spontaneous breathing. These sequential data show similar patterns of change in pulmonary mechanics during high-frequency ventilation and conventional mechanical ventilation irrespective of gestational age, birth weight stratification, or bronchopulmonary dysplasia. There was no significant difference in the pulmonary functions with either mode of ventilation during the acute phase (≤4 weeks) of respiratory disease. When evaluated by the clinical diagnosis of bronchopulmonary dysplasia, the pulmonary data suggested a less severe dysfunction in the high-frequency oscillatory ventilation-treated bronchopulmonary dysplasia group compared with the conventional mechanical ventilation-treated group. These results indicate that high-frequency oscillatory ventilation in preterm neonates does not reduce the risk of acute lung injury; however, the magnitude of the pulmonary dysfunction in the first 2 weeks of life merits a reevaluation.

Pulmonary gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (5) ◽  
pp. 1278-1287 ◽  
Author(s):  
R. D. McEvoy ◽  
N. J. Davies ◽  
F. L. Mannino ◽  
R. J. Prutow ◽  
P. T. Schumacker ◽  
...  
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Flow Distribution ◽  
Conventional Mechanical Ventilation ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Concentration Difference ◽  
Perfused Lung ◽  
Frequency Ventilation ◽  
The Difference

Gas exchange was investigated in normal anesthetized dogs during high-frequency, low-tidal volume ventilation (HFV) using the multiple inert gas elimination method. The pattern of inert gas elimination was initially normal during conventional mechanical ventilation. During HFV there was an increase in the difference between the excretion values of acetone and its less soluble neighboring gases, enflurane and ether, but elimination was independent of molecular weight. This pattern was consistent with a major degree of parallel ventilation-perfusion inequality with 49.4 +/- 1.7% of alveolar ventilation being distributed to lung units with VA/Q ratios greater than 20. Additional experiments, however, showed insufficient change in pulmonary blood flow distribution during HFV to account for these apparently poorly perfused lung units. Instead, it was found that the flux from the lung of the most soluble gas, acetone, per unit concentration difference along the airways was approximately twice that for other gases. Experiments using a simple airway model suggested that this enhanced transport of high-solubility gases during HFV is dependent on the wet luminal surface of conducting airways. A reciprocating exchange of gas between the lumen and airway lining layer is proposed as the most likely explanation for these results.

Ventilation-perfusion relationship during high-frequency ventilation

1984 ◽  
Vol 56 (2) ◽  
pp. 454-458 ◽  
Author(s):  
V. Brusasco ◽  
T. J. Knopp ◽  
E. R. Schmid ◽  
K. Rehder
Keyword(s):  
Mechanical Ventilation ◽  
High Frequency ◽  
Conventional Mechanical Ventilation ◽  
Regional Perfusion ◽  
High Frequency Ventilation ◽  
Regional Ventilation ◽  
Frequency Ventilation ◽  
Anesthetized Dogs

The efficiency of oxygenation and the uniformity of the distribution of regional ventilation (Vr) to regional perfusion (Qr) along the vertical and horizontal axes was compared in anesthetized dogs between conventional mechanical ventilation (CMV) and high-frequency ventilation (HFV) at 5.8, 15.0, and 29.8 Hz. Both CMV and HFV were adjusted to result in similar arterial CO2 tensions. The distribution of Vr/Qr during HFV at 5.8 Hz tended to be more uniform than during HFV at 15.0 or 29.8 Hz or during CMV. Consistent with this observation, arterial O2 tension (PaO2) tended to be higher during HFV at 5.8 Hz (means +/- SD, 90 +/- 9 Torr) than during HFV at 15.0 Hz (83 +/- 9 Torr) or 29.8 Hz (78 +/- 10 Torr); PaO2 was significantly higher during HFV at 5.8 Hz than during CMV (83 +/- 7 Torr).

High-Frequency Ventilation and Tracheal Injuries

PEDIATRICS ◽  
1986 ◽  
Vol 77 (4) ◽  
pp. 608-613
Author(s):  
Mark C. Mammel ◽  
Janice P. Ophoven ◽  
Patrick K. Lewallen ◽  
Margaret J. Gordon ◽  
Marylyn C. Sutton ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
High Frequency ◽  
Conventional Mechanical Ventilation ◽  
High Frequency Ventilation ◽  
Jet Ventilation ◽  
Standard Frequency ◽  
High Frequency Jet Ventilation ◽  
Frequency Ventilation ◽  
Tissue Changes ◽  
Adult Cats

Recent reports linking serious tracheal injuries to various forms of high-frequency ventilation prompted this study. We compared the tracheal histopathology seen following standard-frequency, conventional mechanical ventilation with that seen following high-frequency, conventional mechanical ventilation, and two different forms of high-frequency jet ventilation. Twenty-six adult cats were examined. Each was mechanically ventilated for 16 hours. Seven received standard-frequency, conventional mechanical ventilation at 20 breaths per minute. Seven received high-frequency, conventional mechanical ventilation at 150 breaths per minute. Six received high-frequency jet ventilation at 250 breaths per minute via the Instrument Development Corporation VS600 jet ventilator (IDC). Six received high-frequency jet ventilation at 400 breaths per minute via the Bunnell Life Pulse jet ventilator (BLP). A semiquantitative histopathologic scoring system graded tracheal tissue changes. All forms of high-frequency ventilation produced significant inflammation (erosion, necrosis, and polymorphonuclear leukocyte infiltration) in the trachea in the region of the endotracheal tube tip. Conventional mechanical ventilation produced less histopathology than any form of high-frequency ventilation. Of all of the ventilators examined, the BLP, the ventilator operating at the fastest rate, produced the greatest loss of surface cilia and depletion of intracellular mucus. IDC high-frequency jet ventilation and high-frequency, conventional mechanical ventilation produced nearly identical histologic injuries. In this study, significant tracheal damage occurred with all forms of high-frequency ventilation. The tracheal damage seen with high-frequency, conventional mechanical ventilation suggests that ventilator frequency, not delivery system, may be responsible for the injuries.

Oxygenation during High-Frequency Ventilation Compared with Conventional Mechanical Ventilation in Two Models of Lung Injury

1982 ◽  
Vol 61 (4) ◽  
pp. 323???332 ◽  
Author(s):  
Michael Kolton ◽  
Charles B. Cattran ◽  
Geraldine Kent ◽  
George Volgyesi ◽  
Alison B. Froese ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
High Frequency ◽  
Conventional Mechanical Ventilation ◽  
High Frequency Ventilation ◽  
Frequency Ventilation
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