2. “ فإذا سويته ونفخت فيه من روحي فقعوا له ساجدين “ ص ۷۲

3. Mechanical Ventilation in Severe Airflow Obstruction Nabil Abouchala, MD Consultant Pulmonary & Critical Care Medicine abouhani@yahoo.com

5. Chronic lung diseases with airflow obstruction Asthma Chronic Bronchitis Emphysema

6. Chronic lung diseases with airflow obstruction Asthma Chronic bronchitis Emphysema

7. Asthma Emphysema Bronchitis

8. Potentially fatal asthma 5000 deaths/yr in US Two variants: Two variants: –progressive worsening 1-3 days –“sudden death” Risk factors Risk factors –History of near fatal asthma/intubations –Frequent hospitals/EDs (> 2/year) –Co-morbidities (CV, COPD. Psych, drug abuse) –Frequent meds (>2 puffers/month) –Poor socioeconomic status

9. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

12. Arterial blood gas measurements Mountain & Sahn Mountain & Sahn –50% of men and 18% of women with acute asthma presented with increase PaCO 2 –only 8% required mechanical ventilation.  PaCO 2 resolved in 5-9 hours 1/3 of acute asthmatics develop lactic acidosis which reflect life-threatening feature of acute asthmatic attack. Less % from high B-2 agonist I.V. 1/3 of acute asthmatics develop lactic acidosis which reflect life-threatening feature of acute asthmatic attack. Less % from high B-2 agonist I.V.

13. Other Tests ECG changes sinus tachycardia ECG changes sinus tachycardia –RV stain (RH axis deviation + hypertrophy pattern Purulent mucous sputum not necessarily bacterial infection gram stain is important Purulent mucous sputum not necessarily bacterial infection gram stain is important  K from B2-agonist, steroid and respiratory alkalosis  K from B2-agonist, steroid and respiratory alkalosis  Glucose from steroid therapy  Glucose from steroid therapy

17. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

18. Which Patients with COPD benefit from NIV ?

19. Which Patients with COPD benefit from NIV ? Hospital Mortality 12% 2% NNT 8

20. Which Patients with COPD benefit from NIV ? Hospital Mortality 12% 2% NNT 8

21. Which Patients with COPD benefit from NIV ? Hospital Mortality NNT 8

22. Target Treatment for Maximum Benefit of NIV in COPD Exacerbations Likely to improve Severity Likely to Fail NIV Target group for NIV Potential Benefit Less severe Higher pH > 7.30 Very severe COPD exacerbation Severe hypercapnia (PCO2 > 90) Severe acidemia pH < 7.10

23. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

24. Case presentation A 68-year-old man with COPD is brought to the emergency room in severe respiratory distress. The man weighs 65 kg (143 lb). Arterial blood gases document severe respiratory acidosis (PaCO2 is 104 mm Hg; pH is 7.10). After providing tracheal intubation and sedation, you order positive pressure ventilation in the assist control (AC) mode. The most appropriate ventilatory setting at this point: RR TVPeak inspiratory (mL)flow rate (L/min) _ A. 2860040 B. 16100060 C. 24100080 D. 1050080 E. 3040040

25. Tidal ventilation Lung volume VT FRC V T V EE Time VEI I :E 1:1 I : E 1: 6 Air-trapping in Asthma/COPD Patients on Mechanical Ventilation

26. Obstructive Airway Disease Beware of auto-PEEP! Beware of auto-PEEP!

29. Excessive Inspiratory Time Inspiration ExpirationNormalPatient Time (sec) Flow (L/min) Air Trapping Auto-PEEP } Increase WOB and “Fighting” of the ventilator

30. Case presentation A 35-yr-old male is admitted with severe bronchial asthma requiring ventilatory support. He is fully sedated and paralyzed, on assist-control mechanical ventilation with a set rate of 15 breaths/min; tidal volume of 1000 mL, and an inspiratory flow rate of 60 L/min, which gives an inspiratory- expiratory (I:E) ratio of 1:3. He is not on any PEEP, and an end-expiratory hold maneuver reveals an auto PEEP of 15 cm H2O. Which one of the following options is most effective in minimizing the auto-PEEP? A. Decreasing the RR 12 /min, giving an I:E ratio of 1:4 B. Increasing the flow to 120 L/min, giving an I:E ratio of 1:7 C. Decreasing the tidal volume to 900 mL D. Adding an external PEEP of 5 cm H2O

31. Auto-PEEP 15 20 A A B B Measurement of auto-PEEP by expiratory occlusion

32. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

33. Pressure or Volume Mode? Volume Predictable TV Predictable TV Peak-Plat gradient Peak-Plat gradient Monitor Plat Monitor Plat Better acidosis control Better acidosis controlPressure Minimise over- distension Minimise over- distension Monitor Tidal volume Monitor Tidal volume Excess volumes as airway resistance improves Excess volumes as airway resistance improves

34. Initial Ventilator Settings Inspiratory time 0.8 – 1.2 secs Inspiratory time 0.8 – 1.2 secs RR 10-12 RR 10-12 TV 6-8 ml/Kg TV 6-8 ml/Kg Pplat < 30 cm H2O Pplat < 30 cm H2O PEEP ?? PEEP ??

35. Assessment of Hyperinflation

36. CVS effects  disconnect Pplat PEEPi measurement

37. Reducing Hyperinflation Reduce rate Reduce rate Reduce tidal volume Reduce tidal volume Increase expiratory time Increase expiratory time –Increase inspiratory flow rate –Increased Peak Airway Pressure Monitor (Pplat) Monitor (Pplat) Tolerate increased CO2 Tolerate increased CO2 (minimise dead space) I : E 1: 6 I : E 1: 2

38. Hypercapnia: How permissive? Defence of intracellular pH Defence of intracellular pH Apnoeic oxygenation in dogs to pH 6.5 and PaCO2 of 55kPa Apnoeic oxygenation in dogs to pH 6.5 and PaCO2 of 55kPa Anaesthetic mishap with PaCO2 of > 300 mmHg (40 kPa) and pH of 6.6 survived without sequelae Anaesthetic mishap with PaCO2 of > 300 mmHg (40 kPa) and pH of 6.6 survived without sequelae Am J Respir Crit Care Med 1994; 150:1722-37

39. Hypotension after initiation of Mechanical Ventilation Conversion to positive intrathoracic pressure Conversion to positive intrathoracic pressure –Decreased venous return, cardiac output –Exacerbated by hypovolemia Auto-PEEP increases intrathoracic pressure Auto-PEEP increases intrathoracic pressure

40. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

42. Ppl EPP Pel Palv Pao 10 +10 10 0 0 Waterfall Concept Flow Limitation Theory 10 EPP Upstream segment Upstream segment Downstream segment Downstream segment Turbulent flow (Density dependent) Turbulent flow (Density dependent) Laminar flow (Viscosity dependent) Laminar flow (Viscosity dependent)

43. Ppl EPP Pel Palv Pao 10 +10 10 0 0 Waterfall Concept External & Internal PEEP 10

44. External PEEP Offload effects of PEEPi Offload effects of PEEPi –Waterfall theory PEEPi not additive until above critical closing pressure of airway Reduce inspiratory muscle load Reduce inspiratory muscle load Improve ventilator triggering Improve ventilator triggering Excess level will increase hyperinflation Excess level will increase hyperinflation 80% of PEEPi can be matched without increase PEEP tot 80% of PEEPi can be matched without increase PEEP tot ?? reduce hyperinflation by improving expiration ?? reduce hyperinflation by improving expiration

45. Titrating PEEP to PEEPi  until no missed trigger efforts  until no missed trigger efforts Minimise inspiratory effort Minimise inspiratory effort –Clinically –Oesophageal pressure/CVP Until increase in hyperinflation Until increase in hyperinflation –Pplat on volume modes –Until TV reduces on Pressure control

46. Titrating PEEP to PEEPi

49. Heliox and Obstructive Airway Disease Low density high thermal conductivity Low density high thermal conductivity Reduce pressure gradient in turbulent flow Reduce pressure gradient in turbulent flow Influences flow sensors Influences flow sensors Administered in NIV, IPPV and to drive nebulisers Administered in NIV, IPPV and to drive nebulisers Role in Asthma and COPD? Role in Asthma and COPD?

51. Helium-oxygen mixture in intubated patients with status asthmaticus and respiratory acidosis Helium-oxygen mixture in intubated patients with status asthmaticus and respiratory acidosis Gluck et al. Chest 1990; 98:693-98 N= 7 patients intubated for ARF/Status asthmaticus Entry criteria Persistent hypercapnia (PCO 2 >50), and acidosis (pH<7.20) after 1 hour of conventional ventilation Persistently elevated peak pressure> 75 cmHO All patients switched to Bear 1 ventilator Ventilation mixture: 60% Helium, 40% Oxygen for 6.3 hours (SEM± 2.3 hours) All patients were extubated within 24 hours without complications

53. Chest 2003; 123:882–890 Meta-analysis in Asthma

54. Chest 2003; 123:891–896

57. Ventilation in COPD/Asthma Non Invasive VentilationAssessment of mechanics (resistance, auto-PEEP)Pressure or volume modes?Role of PEEPAdministering Bronchodilators

58. Theophylline Used for OVER 50 years Lack of benefit has been shown when aggressive inhalation B2-agonist + systemic corticosteroids

59. Administration of Bronchodilators Nebuliser or MDI? Nebuliser or MDI? Lung deposition of radiolabelled drug* Lung deposition of radiolabelled drug* –MDI 5.6% v Nebuliser 1.2% Urinary excretion** Urinary excretion** –MDI with spacer 38% –MDI in line 9% –Nebuliser 16% 4-10 puffs MDI effective in reducing R AW 4-10 puffs MDI effective in reducing R AW

60. Administration of Bronchodilators Nebuliser or MDI? Nebuliser or MDI? Lung deposition of radiolabelled drug* Lung deposition of radiolabelled drug* –MDI 5.6% v Nebuliser 1.2% Urinary excretion** Urinary excretion** –MDI with spacer 38% –MDI in line 9% –Nebuliser 16% 4-10 puffs MDI effective in reducing R AW 4-10 puffs MDI effective in reducing R AW * Chest 1999; 115:1653-1657 **Am Rev Respir Dis 1990; 141:440–444

61. Administration of Bronchodilators

64. Outcome of Ventilation & COPD 166 patients requiring MV 166 patients requiring MV Median duration 4.1 days Median duration 4.1 days 9% required > 21 days ventilation 9% required > 21 days ventilation Hospital mortality 28% Hospital mortality 28% 9% discharged with tracheostomy  MV 9% discharged with tracheostomy  MV 60% of MV time spent weaning 60% of MV time spent weaning Nevins & Epstein Chest 2001;119:1840

65. Weaning and COPD Weaning protocols Weaning protocols Non Invasive ventilation Non Invasive ventilation External PEEP to offload PEEPi External PEEP to offload PEEPi Optimise cardiac function Optimise cardiac function –Diuretics –ACE inhibitors Acetazolamide Acetazolamide

66. Myopathy in Asthma Steroid myopathy Steroid myopathy Muscle relaxants Muscle relaxants Polyneuropathy of the critically ill Polyneuropathy of the critically ill

67. Myopathy in Asthma Proximal muscle Subacute (3 weeks) Normal CPK Steroid myopathy Distal & proximal High myoglobin High CPK Muscle relaxants Sensorimotor Normal CPK Polyneuropathy of the critically ill

68. Principles of managing the ventilated patient with obstructive lung disease Provide adequate support for muscle rest with adequate pH and PO2 Do not over ventilate Minimize minute volume requirements Minimize the risk of barotrauma Maintain adequate bronchial hygiene Maintain appropriate nutrition