Handling Common Problems & Pitfalls During. Oxygen desaturation in patients receiving mechanical ventilation ACUTE SEVERE RESPIRATORY FAILURE

Transcription

1 Handling Common Problems & Pitfalls During ACUTE SEVERE RESPIRATORY FAILURE Pravit Jetanachai, MD QSNICH Oxygen desaturation in patients receiving mechanical ventilation Causes of oxygen desaturation 1. Disorder of ventilation 1.1 Decreased ventilatory drive - oversedation - CNS problems 1.2 Obstructed ventilation - bronchospasm - dislodgement of ET tube - mucus plugging of airways or ET tube 1

2 Causes of oxygen desaturation 2. Disorder of oxygenation 2.1 pulmonary causes - ARDS - pneumonia, atelectasis - pneumothorax - pulmonary embolus - aspiration pneumonitis Causes of oxygen desaturation 2. Disorder of oxygenation 2.2 Non-pulmonary causes - iatrogenic fluid overload - heart failure 3. Effects on interventions, procedures - chest physical therapy, endotracheal suctioning - changes in body positioning - peritoneal dialysis, hemodialysis - thoracocentesis Causes of oxygen desaturation 5. Medication - bronchodilators - vasodilators -β-blockers 6. Ventilator-related problems - ventilator circuit - function of ventilator itself - inappropriate ventilator settings 2

3 Management desaturation 1. Increased FiO 2 to 100% 2. Check ET tube (obstruction, dislodgement) 3. Briefly physical examination unilateral decreased breath sounds suggest pneumothorax or right main stem bronchus intubation distended neck vein with bilateral lung crackles suggest volume overload Management desaturation 3. Briefly physical examination wheezing represents bronchospasm (can be associated with cardiogenic problems) decreased mental status suggests hypoventilation 4. If cause is not obvious, manually ventilate patient with 100% O 2 to exclude ventilator malfunction Management desaturation 5. Treat underlying cause 6. Alter ventilator settings to improve oxygenation (increase PEEP) 7. CXR (if the cause is still not clear) 3

4 Patient fighting ventilator Fighting ventilator acute respiratory distress Patient and ventilator are breathing out of synchrony (patient shows signs and symptoms of acute respiratory distress, multiple ventilator alarms eg. low tidal volume, high pressure alarm or low pressure alarm, hemodynamic instability, cardiac rhythm changes and abnormal gas exchange) * Physiological effects of patient ventilator dyssynchrony 1. Discomfort 2. Increased work of breathing 3. Increased oxygen consumption 4. Increased minute ventilation 5. Increased cardiac work 6. Respiratory muscle fatigue 4

5 5

6 Patient s expression of fear, feeling of panic can be explored by using direct questions that patient can answer with head nodding or pointing. Primary goal of management - to ensure adequate ventilation / oxygenation and to prevent complications of mechanical ventilation, eg. barotrauma, reduction CO Steps in the management sudden respiratory distress in patients receiving mechanical ventilation 1. Remove patient from ventilator 2. Manual ventilation using self-inflating resuscitation bag containing 100% O 2 (if patient s distress goes away, problem is in ventilator - check circuit for air leaks or condensation that accumulated, adjust setting) Steps in the management sudden respiratory distress in patients receiving mechanical ventilation 2. Manual ventilation using self-inflating resuscitation bag containing 100% O 2 (if distress does not go away, problem is in the patient) 3. rapid physical examination, check cuff pressure 4. assess monitored indices, alarm and graphic waveform 6

7 7

8 Pressure-volume, flow-volume loops: Expiratory volume curve does not go to zero leak in the system Steps in the management sudden respiratory distress in patients receiving mechanical ventilation 5. Check patency of airway, pass suction catheter if catheter cannot pass biting on the tube, obstruction ET tube if obstruction cannot be cleared, ET tube must be removed, mask ventilation until reintubation Steps in the management sudden respiratory distress in patients receiving mechanical ventilation 6. If death appears imminent, consider and treat most likely causes: pneumothorax, airway obstruction (needle inserted into second intercostal space at mid-clavicular line, followed by tube thoracostomy) 7. Once patient is stabilized, perform more detailed assessment and management 8

9 Steps in the management sudden respiratory distress in patients receiving mechanical ventilation 8. Some patient-ventilator dyssynchrony may result from patient s feeling of panic, fear or pain - manually ventilating, instructing how to relax while breathing with ventilator on adjunctive therapy with sedation, analgesic Type of patient ventilator dyssynchrony 1. Trigger dyssynchrony - difficult to trigger ventilator to initiate inspiration Causes 1.1 insensitive trigger high trigger threshold 1.2 autopeep 2. Flow dyssynchrony - ventilator flow not match patient s flow need (VC mode) 9

10 Type of patient ventilator dyssynchrony 3. Termination dyssynchrony - Patient s inspiratory time and ventilator inspiratory time not coincide Causes 3.1 premature breath termination 3.2 delayed breath termination 4. Expiratory dyssynchrony - Due to shortened or prolonged expiratory time, patient s effort during expiration Respiratory acidosis * ph < 7.35 with PaCO 2 > 45 mm Hg 10

11 Hypotension 11

12 Causes of hypotension soon after initiation mechanical ventilation 1. Relative hypovolemia application positive pressure ventilation intrathoracic pressure venous return, preload, cardiac output Causes of hypotension soon after initiation mechanical ventilation 2. Drug induced vasodilatation and myocardial depression 3. Gas trapping (dynamic hyperinflation) 4. Tension pneumothorax Management hypotension - Treat loss vascular tone - vasoconstrictors - Treat lowered stroke volume fluid bolus - Hypotension due to relative hypovolemia or anesthetic induction agents responds rapidly to fluid - Gas trapping disconnecting - Tension pneumothorax chest tube insertion 12