Weaning: Neuro Ventilatory Efficiency · 2019. 9. 27. · Weaning: Neuro Ventilatory Efficiency...
Transcript of Weaning: Neuro Ventilatory Efficiency · 2019. 9. 27. · Weaning: Neuro Ventilatory Efficiency...
Weaning: Neuro Ventilatory Efficiency
Christer Sinderby Department of Critical Care
Keenan Research Center at the Li Ka Shing Knowledge Institute of St. Michael's Hospital
Faculty of Medicine, University of Toronto, Canada
Disclosure: Dr. Sinderby has made inventions related to neural control of mechanical ventilation that are patented. The license for these patents belongs to
Maquet Critical Care. Use of this technology provides financial benefit to Dr. Sinderby through royalties. Dr Sinderby owns 50% of Neurovent Research Inc
(NVR). NVR is a research and development company that builds the equipment and catheters for research studies. NVR has a consulting agreement with
Maquet Critical Care.
Conflict of interest• Disclosure: Dr. Sinderby has made inventions related to neural
control of mechanical ventilation that are patented. The license for
these patents belongs to Maquet Critical Care. Commercial use of
this technology provides financial benefit to Dr. Sinderby through
royalties. Dr Sinderby owns 50% of Neurovent Research Inc (NVR).
NVR is a research and development company that builds the
equipment and catheters for research studies. NVR has a
consulting agreement with Maquet Critical Care.
Neuro-ventilatory efficiency = Vt/EAdi (ml/µV)
Sinderby & Beck, Neurally Adjusted Ventilatory Assist in
Principles and Practice of Mechanical Ventilation, Third Edition
Editor: Tobin MJ, McGraw-Hill Medical 2013
EAdi and Vt in health and disease
Principle for Vt/EAdi
Vt
EAdi
We evaluated whether extubation failure could be characterized
by increased respiratory drive and impaired efficiency to generate
inspiratory pressure and ventilation.
Following PSV of 10 cm H2O and PEEP of 5 cm H2O: 52
patients underwent 30-minutes of spontaneous breathing on
CPAP of 5 cmH2O.
Data was compared between successfully extubated patients and
those patients that either failed spontaneous breathing or passed
but failed within 48 h.
• Purpose: To compare breathing pattern descriptors and diaphragm
electromyographic activity (EAdi) during a spontaneous breathing trial (SBT) in
patients successfully and unsuccessfully separated from the ventilator and to assess
their performance as a potential marker to discriminate these two categories of
patients.
• Methods: Fifty-seven ready-to-wean patients were included in a prospective
observational study. During a 30-min SBT (pressure support 7 cmH2O, zero end
expiratory pressure), tidal volume (VT) and respiratory rate (RR) were obtained
from the flow signal at baseline of PSV and at 3, 10, 20 and 30 min during the
SBT.
Note that this study describes the inverse of Neuro-Ventilatory Effiency
ConclusionsEAdi-derived indices collected via the NAVA catheter during the SBT provide
reliable predictors of successful separation from the ventilator. These indices
can discriminate early in the SBT the ongoing success or failure of separation
from the ventilator. However, the performance of these indices is not better
than the performance of the rapid shallow breathing index. Therefore, the
benefit of EAdi-derived indices during the SBT remains unclear.
• In this pilot study we compared the EAdi to conventional weaning parameters in
difficult-to-wean patients scheduled for a spontaneous breathing trial. Our primary
goal was to observe the expected increase in the EAdi. A secondary goal was to
compare the conventional weaning parameters to those derived from the EAdi.
• We studied 18 mechanically ventilated patients considered difficult to wean. For a
spontaneous breathing trial (SBT) the patients were disconnected from the
ventilator and given oxygen through a T-piece. The SBT was evaluated using
standard criteria.
This observational study included 12 patients breathing with neurally
adjusted ventilatory assist (NAVA). When a spontaneous breathing trial
(SBT) with pressure support of 7 cm H2O and PEEP was unsuccessful,
NAVA was used and the level was adjusted to obtain an EAdi of 60% of
maximal EAdi during SBT. VT and EAdi were recorded continuously.
We compared changes in NVE between NAVA and SBT at the first failed
and first successful SBT.
ConclusionsThese results suggest that in patients after respiratory failure and prolonged
mechanical ventilation, changes in VT and NVE, between SBTs are indicative
of patient recovery. Larger clinical trials are needed to clarify whether changes
in NVE reliably predict weaning in patients ventilated with NAVA.
Conclusion
4 studies in 138 patients indicate that neuroventilatory efficiency
(Vt/EAdi) is reduced in weaning failure patients. Thus, clinical
use of mechanical ventilation to unload inspiratory muscles due
to weakness or load is justified.
Vt/EAdi as a predictor of weaning during SBT equals that of
Fb/Vt.
Future studies of comparing patient-chosen changes in Vt,
Vt/EAdi, and Fb/Vt between NAVA and SBT may introduce
better prediction of weaning outcome.
Thank You
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