1. Difficult Weaning

2. Indications for mechanical ventilation: • A) Global pathophysiological indications: • Apnea • - Acute ventilatory failure • impending failure • Refractory hypoxemia • Signs of respiratory failure • B) Common clinical conditions when need for ventilatory support is high: • ARDS • Asthma • COPD • Chest trauma • Overdose • Post cardiac surgery • Pneumonia • Sepsis • Head Trauma

3. Preparing the Patient for Weaning: • Electrolyte Disturbance • Volume Overload • Altered Mental status • Fatigue of the diaphragm • Adequacy of sleep and sleep deprivation • Malnutrition

4. Criteria to consider Patients for Weaning: • Reversal of underlying pathology • Po2, PEEP, FiO2, PH • ABG • Vital Data • CXR • Parameters Predicting successful Weaning: • Respiratory rate • Tidal Volume • Minute Ventilation • Negative inspiratory force • Maximal Inspiratory pressure • RSBI • RSBI rate

5. Algorithm for weaning Protocol

6. New Advances in Ventilators to assist Weaning: - Automated tube compensation (ATC) - Proportional Assisted ventilation(PAV)

7. Causes of Difficult Weaning Imbalance Respiratory muscle pump Respiratory muscle load A) Increased Ventilatory Needs Increased resistive load Increased chest Wall Load Increased parenchyma load • Bronchospasm • Airway edema • Airway obstruction • Tube kinking • Sleep Apnea • Secretions • Circuit resistance • Pleural effusion • Pnumothorax • Flail chest • Obesity • Ascites • Distension • Hyperinflation • Inflammation • Atelectasis • Alveolar edema

8. B) Decreased Neuromuscular compliance: Muscle Weakness Impaired Transmission Decreased Drive Drug overdose - Electrolyte derangement - Critical illness polyneuropathy Brain-stem lesion - Malnutrition - Neuromuscular blockers Sleep deprivation - Myopathy - Aminoglycosides Hypothyroidism - Hyperinflation - Guillain–Barré syndrome Starvation/malnutrition - Drugs, corticosteroids - Mysthenia gravis Metabolic alkalosis - Sepsis - Phrenic nerve injury Myotonic dystrophy

9. How to Wean Difficult to Wean Patients Correction of Causes Choice of appropriate mode Tracheostomy

10. Neuromuscular Weakness in Critically Ill Myopathy: Critical illness polyneuropathy (CIP): Disorders of neuromuscular transmission: Critical illness Polyneuropathy Definition Course Causes Diagnosis: - EPS: shows reduced compound motor and sensory nerve action potential amplitudes with normal conduction velocities. - Needle EMG reveals fibrillation potentials and positive sharp waves indicating denervation Treatment

11. Disorders of neuromuscular transmission: • Prolonged use of neuromuscular blockers • Decreased Metabolism • Decremental Response • Aminoglycosides, Polypeptide antibiotics

12. Myopathy: 1. Critical illness myopathy: • Histological Pattern • Normal CPK levels • Type II myofibres • IL-1, TNF 2. Thick filament myopathy: • Selective loss of myosin • Absent neuropathy • Increased steroid receptors • Triggering factors: NMBA, Denervation • Diagnosis: EPS, CPK , Muscle biopsy

13. 3. Necrotizing myopathy: • Prominent muscle necrosis • CPK elevated • Correlated with NMBA, Steroids • Diagnosis: - difficult to diagnose • - Direct muscle stimulation and calculation of the ratio of nerve and muscle evoked compound muscle action potential amplitudes. • - Muscle biopsy is of choice • No specific treatment is available

14. Prevention of neuromuscular weakness in ICU: - Appropriate treatment of sepsis - Minimize use of NMBA - Check serum electrolytes -Avoid Pharmacological agents causing weakness - Early EPS

15. Thank You