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.
Limitations
It would be recommended to set iBR to the patient’s spontaneous respiratory rate (i.e. 16 bpm) and re-evaluate Ti Max.
SpO2was not normalised despite pressure reaching Max PS. Therefore consider increasing Max PS and EPAP.
Conclusions
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.
