Open AccessUnder Open Lung Conditions Inverse Ratio Ventilation Causes Intrinsic Peep and Hemodynamic Impairment
Author(s) -
Agneta Markström,
Michael Lichtwarck-Aschoff,
Anders Hedlund,
K. A. Nordgren,
Ulf Sjöstrand
Publication year - 1996
Publication title -
upsala journal of medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 41
eISSN - 2000-1967
pISSN - 0300-9734
DOI - 10.3109/03009739609178925
Subject(s) - medicine , positive end expiratory pressure , ventilation (architecture) , expiration , mean airway pressure , hemodynamics , functional residual capacity , anesthesia , tidal volume , cardiology , cardiac output , mechanical ventilation , lung , lung volumes , respiratory system , mechanical engineering , engineering
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, extrathermal 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.