RT Journal Article
SR Electronic
T1 Objective evaluation of patient–ventilator interactions during noninvasive ventilation (NIV)
JF European Respiratory Review
JO EUROPEAN RESPIRATORY REVIEW
FD European Respiratory Society
SP 22
OP 23
DO 10.1183/09059180.00010706
VO 17
IS 107
A1 Herinaina Rabarimanantsoa
A1 Linda Achour
A1 Christophe Letellier
A1 Jean-Francois Muir
A1 Antoine Cuvelier
YR 2008
UL http://err.ersjournals.com/content/17/107/22.abstract
AB The success of NIV depends on patient–ventilator interactions. These interactions are evaluated with the subjective comfort score which is not always reliable. An objective evaluation is thus required. To evaluate these interactions, we use a statistical measure of the variability of a physiological signal, i.e the Shannon entropy. Our purpose is to show whether estimating Shannon entropy from airway pressure (SP) and from the total duration of ventilatory cycles (ST) may evaluate objectively the patient–ventilator interactions during NIV. Pressure support NIV was applied to 4 COPD patients, 4 OHS patients in stable state and 4 healthy subjects during six successive 10-min periods with various inspiratory pressure. The flow and the airway pressure signals were recorded with sensors located near the mask. Good patient–ventilator interactions were assumed to correspond to patient well synchronized (low ineffective efforts) and with low ventilatory variability. All the subjects were awaked and both Shannon entropies SP and ST were computed for each ventilatory tracing. The incidence of ineffective efforts (IE) varied from 0 to 64.7 %. SP appeared to be strongly correlated to this incidence (r = 0.91). ST quantified precisely the ventilatory variability. When SP was plotted versus ST, 4 distinct groups of patients were distinguished as follows: SP<1 and ST<1: IE<10% but no ventilatory variability SP<1 and ST>1: IE <10% with high ventilatory variability SP>1 and ST<1: IE >10% but no ventilatory variability SP>1 and ST>1: IE > 10% with high ventilatory variability Shannon entropies objectively evaluate the patient–ventilator interactions in terms of ineffective efforts and ventilatory variability. Good patient–ventilator interactions occur when there is only few ineffective efforts (SP<1) and a low ventilatory variability (ST<1).