IRV (ventilation mode)

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For ventilation with Inversed Ratio Ventilation ( IRV ), the breathing time ratio or I: E ratio ( I = inspiration [inhalation], E = expiration [exhalation]) is reversed. From this follows one

  • Extension of the inspiration time at the expense of the expiration time (in extreme cases I: E = 4: 1)
  • Increase in the mean ventilation pressure

IRV is used for severe gas exchange disorders in the lungs, in particular for restrictive (restrictive) breathing disorders. The positive effect on oxygen saturation (oxygenation) is brought about by:

  • more even distribution of the gas in the lungs
  • better ventilation of lung areas with increased airway resistance (more time to open unventilated ( atelectatic ) lung areas).
  • longer contact time of the gas in the lungs.

However, IRV also has disadvantages: The increase in the mean ventilation pressure and thus the pressure in the chest cavity leads to a decrease in the venous return flow to the right heart, which in turn also reduces the cardiac output and thus the blood flow to the organs. In addition, an “intrinsic PEEP ” can build up due to the short expiration time . Their use is reserved in exceptional cases.