Comparison of S/T mode with iVAPS mode for a COPD patient1

A case study

Hideki Ishihara, Director of the Department of Respiratory Medicine and Intensive Care Osaka Prefectural Medical Centre for Respiratory and Allergic Diseases, Japan.

Patient history

  • Eighty-three year old male with COPD.
  • Eight years of NIV therapy (with Mirage QuattroTM mask) to treat hypoventilation, in addition to having long term oxygen therapy.
  • Nocturnal desaturation was observed so patient was re-admitted to adjust NIV settings.

Challenges with initial treatment:

  • The patient reported discomfort and felt that the air was being “pushed in” despite the need to exhale.
  • He also experienced discomfort when falling asleep.
  • ResScan shows intermittent leak.
  • Despite these settings, desaturation was observed during REM sleep.
  • Therefore, a means to improve desaturation while addressing patient comfort, was required.

Switch to iVAPS mode

Basis for settings

  • The target alveolar ventilation volume was calculated at 5.1 L/min using tidal volume measured in S/T mode and using the Va calculator.
  • Min PS was kept at the default of 2 cm H2O. Max PS was set to IPAP from S/T mode plus 1 cm HO.
  • Overall, there was an improvement in several parameters, as shown in the figures below.
  • On iVAPS mode, there was increased spontaneous breathing and target alveolar ventilation was achieved.
  • Patient no longer complained of high pressure when falling asleep. Due to improved comfort, there was better therapy adherence.
  • More spontaneous triggering and cycling.


  • It would be recommended to set iBR to the patient’s spontaneous respiratory rate (i.e. 16 bpm) and re-evaluate Ti Max.
  • SpO2 was not normalised despite pressure reaching Max PS. Therefore consider increasing Max PS and EPAP.


  • COPD patient who had nocturnal desaturations was treated on both S/T mode and iVAPS mode.
  • iVAPS mode improved patient comfort and ventilation.
  • However, care needs to be taken when adjusting settings from S/T mode to iVAPS mode.
  • By optimising settings, normalised gas exchange is expected to be achieved in this patient.



Adapted from: Teijin Pharma Limited


Adapted from: Teijin Pharma Limited