Effect Of Weaning Ventilatory Thchnioues On Duration And Success Rate Of Weaning From Mechanical Ventilation

Decisions about when and how to wean patients are higWy empirical, and further systemic studies in the area of weaning from mechanical ventilation are needed, before knowledge in this area can truly be called a science.We studied 50 patients (40% were females) they were suffering from ARF They divided into 5 groups (10 patient in each one). Each group was submitted to different mode of weaning after a period of controlled ventilation during which best efforts were done to treat the cause of respiratory failure .- During period of controlled ventilation, muscle relaxant and sedation were used.During period of weaning, patients were allocated into 5 equal groups according to weaning techniques as the following.Group used (SIMV) Group used (SIMV + FB) Group used (PS)Group used (PS + FB)Repiratory Mechanics: mean airway pressure - V.C. - N.I.F. comp liance-resistance- Cas exchange: PH, Pa02, PaC02, Sa02 V02, VC02, QS/Qt, P(A-a)02 and D20.(WOB) ”not measured” But as indicated by inspiratory area (base line pressure was adjusted to zero) and total area (base line adjusted to levels more than the peak airway pressure) on pressure volume curve (option 60 on the ventilator.Our purpose was to conduct an assessement of efficacy and efficiency of using these different modes to wean patient from mechanical ventilation and reduce the duration of weaning process.Prolonged weaning period from mechanical ventilation is in part attributed to inadequate understanding of the mechanics responsible for this prolongation and lack of guidelines regarding the optimal approach to the process of weaning.The duration of weaning was explained first by the severity of the disease and second by the mode of ventilation. Although conflicting results have been published, no clear superiority of one technique over the other has emerged. However, the choice ofwearung mode remams, a major concern for practitioners. It is generally agreed that, selection of weaning mode is determined by availability as well as clinician preference.We found in this study there is no difference in duration of weaning with the use of [(PS), (SIMV), modes while (P.S + F.B), (SIMV + F.B)] and (SIMV + PS + F.B) showed prolongation of duration and low sucess rate of weaning.Marked reduction in (WOB) by the use of varient options like (P.S.) and (F.B) may cause detraining of respiratory muscles and delay weaning. So the use of this options should be titrated likely (P.S) should not exceed best pressure support and with (F.B) no need to exceed 5 Lpm in base flow.All weaning options affect in respiratory mechanics to varient degree.- These is no difference in blood geses exchange with 5 group.However (P.S.V) has tendency to improve it- WOB was markedly reduced also V02 & veo2 were reduced with (SIMV + P.S. + F.B) and we should avoid marked reduction in (WOB).