[Preliminary study about the utility of gastric tonometry during the weaning from mechanical ventilation].
OBJECTIVE
The intramucosal pHi measurement has been studied and evaluated as a minimally invasive method able to offer information about the tissue oxygenation. It's most important advantage is to be a regional not systemic measurement in a place with early changes of blood flow, even in the compensated states of shock, as the gastrointestinal tract. The weaning from mechanical ventilation may cause cardiac output changes as well as redistribution of blood flow to the respiratory muscles. Our aim was to test the hypothesis that the splanchnic blood flow decreases may occur after patients extubation, detected by pHi reduction, and to verify if pHi can be a good predictive index for weaning from mechanical ventilation.


METHODS
Clinical prospective non-randomized, uncontrolled study, realized in a University Hospital PICU. Assessment of pHi (gastric) in 15 children in the post-operative of elective cardiac surgery with cardiopulmonary bypass. A tonometer with saline solution was used and measurements were made one hour before and after extubation. The patients were divided into two groups with pHi < or = or > 7.32. The Wilcoxon test was used for statistical analysis.


RESULTS
The pHi decreased after extubation in 10 patients (66.7%). The overall mean before extubation was 7.32 +/- 0.10 and after extubation was 7.27 +/- 0.10 (p = 0.096). In the group with pHi < or = 7.32 and > 7.32 the means were 7.25 +/- 0.05 to 7.32 +/- 0.10 (p = 0.72) and 7.41 +/- 0.07 to 7.31 +/- 0.10 (p = 0.059), before and after extubation respectively. None of the patients presented complications due to the procedure; no deaths or development of multiple organ failure occurred. All of the patients were successfully weaned.


CONCLUSIONS
Our results show pHi decreasing confirming splanchnic blood flow reduction after extubation, however in despite of this circulatory change the patients were weaned from mechanical ventilation and successfully extubated. In this trial the pHi was not a good predictive index. The pHi monitoring seems to be useful and reliable, but it requires further studies to evaluate its sensitivity.
Unidade de Cuidados Intensivos Pediátrica, Hospital São Paulo-Escola Paulista de Medicina-Universidade Federal de São Paulo, São Paulo-Brasil.
Renato Lopez
RL
de Souza
Werther Brunow
WB
de Carvalho
D001783:Blood Flow Velocity; D006348:Cardiac Surgical Procedures; D002648:Child; D002675:Child, Preschool; D005753:Gastric Mucosa / Q000098:blood supply; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011184:Postoperative Period; D011446:Prospective Studies; D012121:Respiration, Artificial; D013152:Splanchnic Circulation / Q000502:physiology*; D015300:Ventilator Weaning / Q000009:adverse effects*