Slideshow Transcript

1. Slide 1: NON-INVASIVE VENTILATION- CLINICAL UPDATE Dr Bassel Noureldin Professor of Anesthesia & ICU Ain Shams University Cairo, Egypt
2. Slide 2: Historical Perspective Negative pressure ventilators Tank and Cuirass
3. Slide 3: Historical Perspective • In 1980s it was recognized that delivery of continuous positive airway pressure by close fitting nasal masks for obstructive sleep apnea could also be used to deliver an intermittent positive pressure. • This was followed by improvements in the interface and establishment of role of NIMV in COPD.
4. Slide 4: Advantages of NIMV • Preservation of airway defense mechanism • Patient can eat, drink and communicate • Ease of application and removal • Patient can cooperate with physiotherapy • Intermittent ventilation is possible
5. Slide 5: Advantages of NIMV • Improved patient comfort • Reduced need for sedation • Avoidance of complications of endotracheal intubation • Ventilation outside hospital is possible • Ease to teach paramedics and nurses
6. Slide 6: Disadvantages • Mask uncomfortable/claustrophobic • Time consuming for medical and nursing staff • Facial pressure sores • Airway not protected • No direct access to bronchial tree for suction if secretions are excessive
7. Slide 7: Mechanism of Action • Augments alveolar ventilation and allows oxygenation without raising PaCO2 • Partial unloading of respiratory muscles • Reduces trans-diaphragmatic pressure, pressure time index of respiratory muscles and diaphragmatic electromyographic activity • Resetting of respiratory centre ventilatory responses to PaCO2
8. Slide 8: Prerequisites for successful Non- Invasive ventilation • Patient can control airway and secretions • Adequate cough reflex • Patient is able to cooperate • Patient is able to co-ordinate breathing with ventilator • Patient can breathe unaided for several minutes
9. Slide 9: Prerequisites for successful Non- Invasive ventilation • Haemodynamically stable • Blood pH>7.1 and PaCO2 <90 mmHg • Normal functioning gastrointestinal tract • Improvement in gas exchange, heart rate and respiratory rate within first two hours
10. Slide 10: Indications of NIMV (A) Acute respiratory failure 1. Hypercarbic acute respiratory failure • Acute exacerbation of COPD • Status asthmatics • Acute respiratory failure in Obesity hypoventilation Syndrome • Weaning difficulties • Post surgical respiratory failure and post extubation • Thoracic wall deformities
11. Slide 11: Indications of NIMV 2. Hypoxemic acute respiratory failure • Cardiogenic pulmonary edema • Pneumonia • Post traumatic respiratory failure • ARDS
12. Slide 12: Indications of NIMV • (B) Chronic Respiratory Failure • (C) Immunocompromised Patients • (D) Do Not Intubate Patients
13. Slide 13: Selection Criteria (A) Acute Respiratory Failure At least two of the following criteria should be present: • Respiratory distress with dyspnea • Respiratory rate >25/min • Use of accessory muscles of respiration • Abdominal paradox • pH <7.35 or PaCO2 >45mmHg or PaO2/FiO2 <200
14. Slide 14: Selection Criteria (B) Chronic Respiratory Failure (Obstructive lung disease) Oxygen saturation <88% for >10% of monitoring time despite O2 supplementation
15. Slide 15: Selection Criteria (C) Thoracic Restrictive/ Cerebral Hypoventilation Diseases PaCO2 >55mmHg with nocturnal SaO2 <90% for more than 5 minutes sustained or 10% of total monitoring time
16. Slide 16: Contraindications • Respiratory arrest • Unstable cardio respiratory status • Uncooperative patients • Unable to protect airway- impaired swallowing and cough • Facial, Esophageal or gastric surgery • Craniofacial trauma/burn • Anatomic lesions of upper airway
17. Slide 17: Relative Contraindications • Extreme anxiety • Massive obesity • Copious secretions • Need for continuous or nearly continuous ventilator assistance
18. Slide 18: Choice of Ventilator • NIMV can be given by conventional critical care ventilators or portable pressure or volume limit ventilators. • When critical care ventilator is chosen, there is problem of alarms due to presence of variable leaks, therefore a close monitoring of leaks is mandatory.
19. Slide 19: Choice of Ventilator NIMV is given by especially designed portable pressure ventilator provide a high flow CPAP or Bilevel positive airway pressure generators These devices are sensitive enough for detection of inspiratory efforts even in presence of leaks in the circuits.
20. Slide 20: Interface
21. Slide 21: Interface Interfaces are devices that connect ventilator tubing to the face allowing the entry of pressurized gas • Non irritant material (silicon rubber) • Minimal dead space • Soft inflatable cuff to provide a seal Nasal masks are used most often in chronic respiratory failure while face masks are more useful in acute respiratory failure.
22. Slide 22: Modes of Ventilation All modes of ventilation can be used for applying non-invasive ventilation CPAP • CPAP increases FRC and opens collapsed alveoli. • CPAP reduces left ventricular transmural pressure therefore increases cardiac output. • CPAP by nasal mask provides pneumatic splint for obstructive sleep apnea. • Usually limited to 5-12 cm of H2O, higher pressure result in gastric distension requiring continual aspiration through nasogastric tube.
23. Slide 23: Modes of Ventilation BIPAP • Bilevel positive airway pressure provides two levels of positive pressure. • During exhalation, pressure is variably positive. Airflow in the circuit is sensed by a transducer and augmented to a preset level of ventilation. • Cycling between inspiratory and expiratory modes may either be triggered by the patient's breaths or preset
24. Slide 24: Modes of Ventilation PSV • Non-invasive PSV can be administered with standard critical care ventilator or bilevel portable devices. • PSV has unique ability to vary inspiratory time breath by breath • Drawbacks of PSV: (a) Patient-ventilator asynchrony in COPD (b) Breathing discomfort as inspiratory force is required to trigger the ventilator.
25. Slide 25: Modes of Ventilation Volume limited ventilation • Ventilators are usually set in assist-control mode with high tidal volume (10-15 ml/kg) to compensate for air leak. • Suitable to the patients with obesity or chest wall deformity who need high inflation pressure and in patients with neuromuscular diseases who need high tidal volume for ventilation
26. Slide 26: Modes of Ventilation Proportional assist ventilation (PAV) This is a newer mode of ventilation. In this mode ventilator has capacity of responding rapidly to the patients' ventilatory efforts. By adjusting the gain on the flow and volume signals, one can select the proportion of breathing work that is to be assisted
27. Slide 27: Goals of NIMV Short Term • Relieve symptoms • Reduce work of breathing • Improve or stabilize gas exchange • Good patient-ventilator synchrony • Optimize patient comfort • Avoid intubation
28. Slide 28: Goals of NIMV Long Term • Improve sleep duration and quality • Enhance functional status • Prolong survival • Maximize quality of life
29. Slide 29: Protocol for Non Invasive Ventilation
30. Slide 30: Protocol for Non Invasive Ventilation Procedure for patient setup • Explain to the patient what we are doing and what to expect • Setup the ventilator by the bed side • Keep the head of the patient's bed at >45 degree angle • Choose the correct interface • Turn on the ventilator and dial in the settings • Attach O2 at 2 liters per minute
31. Slide 31: Protocol for Non Invasive Ventilation • Hold the mask gently over the patient's face until the patient becomes comfortable with it. • Strap the face mask on using the rubber head strap and minimize air leak without discomfort. • Connect humidification system. • Monitor- respiratory rate, heart rate, level of dyspnea, O2 saturation, blood pressure, minute ventilation, exhaled tidal volume, abdominal distension and ABG
32. Slide 32: Protocol for Non Invasive Ventilation Initial Ventilatory Settings • Initial ventilator setting should be very low, IPAP of 6 cm H2O and EPAP of 2 cmH2O • Increase EPAP by 1-2 cm increments till the patient triggers the ventilator in all his inspiratory efforts.
33. Slide 33: Protocol for Non Invasive Ventilation • Increase IPAP in small increments, keeping it 4cmH2O above EPAP, to a maximum pressure, which the patient can tolerate without discomfort and major leaks. • Titrate pressure to achieve a respiratory rate of <25 breaths/min and Vt >7ml/kg • Increase FiO2 to improve O2 saturation to 90%
34. Slide 34: Protocol for Non Invasive Ventilation Weaning It is similar to T-piece weaning trials
35. Slide 35: Complications and Side effects • Air leak • Skin necrosis- particularly over bridge of nose • Retention of secretions • Gastric distension • Failure to ventilate • Sleep fragmentation • Upper airway obstruction
36. Slide 36: Before you go • Use of NIMV has increased during the last few years. • For acute exacerbation of COPD it is now the mode of first choice. • For acute pulmonary edema, CPAP alone is very effective. • NIMV reduces the chances of endotracheal intubation in hypoxemic respiratory failure. • NIMV used to facilitate the weaning from invasive ventilation.
37. Slide 37: Happy facts & dreams