Under Open Lung Conditions Inverse Ratio Ventilation Causes Intrinsic Peep and Hemodynamic Impairment

Inverse ratio ventilation (IRV) is commonly used in clinical practice. Several studies have used IRV in order to recruit collapsed alveoli. In a randomised trial in twelve surfactant depleted piglets, the lungs were ventilated with sufficient positive end-expiratory pressure (PEEP) to prevent end-ex...

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Bibliographic Details
Published in:Upsala journal of medical sciences 1996, Vol.101 (3), p.257-271
Main Authors: Markström, Agneta M., Lichtwarck-Aschoff, Michael, Hedlund, Anders J., Nordgren, K. Anders, Sjöstrand, Ulf H.
Format: Article
Language:English
Subjects:
Animals
Hemodynamics
Lung - physiology
Lung Compliance
Oxygen - blood
Positive-Pressure Respiration
Pressure
Pulmonary Circulation
Pulmonary Gas Exchange
Pulmonary Ventilation
Respiration, Artificial
Swine
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Summary:Inverse ratio ventilation (IRV) is commonly used in clinical practice. Several studies have used IRV in order to recruit collapsed alveoli. In a randomised trial in twelve surfactant depleted piglets, the lungs were ventilated with sufficient positive end-expiratory pressure (PEEP) to prevent end-expiratory collapse, and the effects of increased inspiration-to-expiration (I:E ratio) were evaluated. Pressure regulated ventilation (with I:E of 1:1, constant tidal volume and decelerating inspiratory flow) was used at 30 breaths per minute (bpm). I:E ratios of 1.5:1,2.3:1 and 4:1 were applied sequentially. When the I:E ratio was increased, external PEEP had to be reduced in order to keep total PEEP constant. Functional residual capacity, airway pressures, gas exchange, extra-thermal volume and hemodynamics were measured. With I:E ratios above 2:1 intrinsic PEEP was generated and with concomitant decrease in cardiac index. PaO2 was not affected, but oxygen delivery was reduced. It is concluded that I:E ratios of 2:1, or above, generate increased intrinsic PEEP with compromised hemodynamics.
ISSN:0300-9734
2000-1967
DOI:10.3109/03009739609178925