STUDY OF THE CAUSES OF DIFFICULT

Weaning of patients from MV should be planned according to clearly defined clinical and physiological goals , A method that rapidly assesses the patients readiness for extubation would provide clinicians readiness for withdrawal of ventilatory support.It is important to assess different factors that may predict outcome of weaning , this will be useful to shorten the duration of MV and improve the outcome .Components of weaning failure include,respiratory muscle weakess due to hypophosphataemia, disuse atrophy and also due to polyneuropathy with or without myopathy , another componeut include central nervous system drive due to sedation, analgesia coma, increase ICT and hyper capnia, another component include L.V.F , lung filorrosis and broncho spasm.