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.
- 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.