Please see Bibliography of References for a list of abstracts, manuscripts and posters.
Poriazi M, Kontogiorgi M, Angelopoulos E, Kritikos K, Basios N, Nanas S, Roussos C, Routsi C. Int Care Med. 2006;32(Supp 1):S18. Abstract 0054.
Introduction: We hypothesized that the cardiovascular impairment during weaning failure from mechanical ventilation (MV) may also be reflected in microcirculation. We used the noninvasive nearinfrared spectroscopy (NIRS) technique as a tool for assessing the microcirculation impairment.
Methods: We studied 41 mechanically ventilated patients (pts) during a 2-hour T-piece weaning trial. Weaning trial was defined as successful when the pt was able to sustain spontaneous breathing (SBT) without distress. Oxygenation, respiratory rate (RR) and minute ventilation (VE) were measured before and either at 2 hours after disconnection from MV in pts with successful SBT, or at the time of reconnection in those with a failed one. Thenar muscle oxygen saturation (StO2) was monitored by NIRS, at the same time points, by the arterial occlusion method. Hyperemic Response parameters, the ratio of the max value of StO2 after the release of arterial occlusion to its min value during arterial occlusion (HRmax) and the maximal change of StO2 during the phase of reactive hyperemia, were measured.
Results: Twenty-one pts were successful and 20 failed during their weaning trials. SaO2, RR and VE on MV did not differ between the two groups. During weaning trial, Sao2 was decreased in the failure group (FG) from 98.1 to 87.9%(p<0.001), and the frequency/tidal volume (f/TV) index was increased from 30 to 214 breaths/L(p<0.001). During weaning trial, in the successful group SG, SaO2 changed from 98.6 to 96.2%(p=0.002) and f/TV index increased from 31 to 79 breaths/L(p<0.001). At the end of SBT, HRmax was significantly different between two groups, FG 26.33 and SG 52.27(p=0.047), and it was increased to 52.27 in the SG (p=0.013) while it did not change significantly in FG. On MV the maximal change of StO2 during reactive hyperemia was not different between the two groups, while at the end of SBT it was significantly different between the two groups FG 66.0 and SG 70.95(p=0.04).
Conclusion: These data indicate that a microcirculation impairment in pts who fail to wean from MV may occur. Further study is needed to define the hyperemic response parameters provided by the NIRS technique and their role, as well as to assess the microcirculation impairment in weaning failure.