1. People’s Friendship University of Russia, Moscow
THE USE OF INDIRECT CALORIMETER TO OPTIMISE WEANING FROM MECHANICAL VENTILATION IN STROKE PATIENTS
S.D. Beeharry, M.V. Petrova, A.V. Butrov, Storchai M.N
ESICM's 27th Annual Congress LIVES 2014

2. Introduction
Approximately 6 million people worldwide suffer from stroke each year with around 1.2 million in Europe.
Around 25-30% of patients require mechanical ventilation.
The number of patients requiring prolonged mechanical ventilation is rapidly increasing worldwide, due to aging, greater number of co-morbidities, and the increasing availability and effectiveness of this new technology
Prognosis in severe stroke patients requiring mechanical ventilation has often been reported to be poor (58-75% мortality ).

3. Introduction
Respiratory muscle weakness and insufficient nutritional support further lead to mechanical ventilation
Average length of stay on mechanical ventilation is around 42 ± 19 days
Pulmonary complications occur in about 60% of patients.
Weaning from mechanical ventilation remains a challenge in these patients.
Some studies showed that Indirect calorimeter parameters (VO2 and VCO2) may be used during weaning as a predictive factor for readiness to wean, while other studies showed that the sensitivity and specificity of VO2 and VCO2 appear insufficient for evaluation of weaning decisions

4. Aim
The purpose of our study was to understand if we can use ∂ VO2 and ∂ VCO2 as a predictor for successful weaning from prolonged mechanical ventilation.
Study design:
prospective, cohort study
Primary target:
successful weaning
from mechanical ventilation

5. Materials and Methods
21 stroke patients on prolonged mechanical ventilation (14 women and 7 men with an average age of 72.4±5.2)
VO2 and VCO2 were measured using Indirect Calorimeter's gas analyser (E-COVX)
Classical algorithm of weaning strategies was used to wean patients to CPAP (stepwise reduction of mandatory breaths in Bi-level mode with Pressure support of 16 mm H2O, followed by continuous positive airway pressure (CPAP) mode with decreasing Pressure support from 16 to 6 mm H2O)
The volume of O2 consumption during different levels of (Psupp) Pressure support of CPAP were noted. The same was recorded for carbon dioxide production.
Weaning procedure lasted hours with changes in parameters every 2-3 hrs
Weaning criteria: CPAP,SpO2>95, compliance > 45 mm H2O
Control: heart rate, respiratory rate, SpO2 and visual evaluation

6. Trend VO2 Weaned and non weaned
Mean ∂ VO2 = 61 ml
Mean ∂ VO2 = 18 ml
VO2 /mL
VO2 /mL
P supp / mm H2O

7. Trend VCO2 weaned/non weaned
Mean ∂ VCO2 = 24 ml
Mean ∂ VCO2 = 78 ml/min
VCO2 /mL
VCO2 /mL
P supp / mm H2O

8. Results
∂ VO2 and ∂ VCO2 in the weaned group was 18 mL (7.8%) and 24 mL (14.6%) respectively whereas in the non weaned one was 61 mL (27.2%) and 78 mL (43.3%) respectively.
14 out of 21 patients were successfully weaned, 4 weaned patients still needed further mechanical ventilation.
Weaned
Non weaned
C I
∂ VO2 18
61*
p <0,05
∂ VCO2 24
78*
It is very important, that ∂ VO2 and ∂ VCO2 have a more rapid response compared to changes in arterial blood gas analysis, clinical signs of respiratory failure.
∂= mean difference in VO2 or VCO2 during one step decrease in different
levels of Psupp

9. Conclusion
Changes in VO2 and VCO2 during one step decrease in different levels of Psupp
may be used as a predictive factor for weaning in stroke patients
In the near future our research will be directed to find the correlation between delta VO2/delta VCO2 and ventilator/respiratory work and hemodynamic changes