PROF. M.K.ARORA DEPARTMENT OF ANAESTHESIA AIIMS

1. Management of Critically Ill Patient in the ICU:Devices for Oxygen TherapyVentilatory Modes for mechanical Ventilation PROF. M.K.ARORA DEPARTMENT OF ANAESTHESIA AIIMS www.anaesthesia.co.inanaesthesia.co.in@gmail.com

2. Oxygen therapy

3. Indications for oxygen therapy • To correct hypoxemia V/Q mismatch ↓ Diffusion Hypoventilation • To ↑ dissolved oxygen Anemia Cyanide and CO poisoning • ↑ Oxygen demand High altitude Shivering Thyroid crisis Hyperthermia • Anaesthesia- Preoxygenation

4. Anoxia No oxygen availability in tissues • Hypoxia Lack of oxygen availability in tissues • Hypoxaemia Lack of oxygen in the blood

5. Tachypnea Paleness Tachycardia Mild hypertension Restlessness Headache Lassitude Tachypnea Cyanosis Bradycardia Arrythmias Hypotension Confusion Impaired judgement Signs of hypoxia Mild to moderate Severe

6. Classification • According to design • Low flow • Reservoir • High flow • Enclosure • According to performance • Fixed • variable

8. According to design • Low flow Gas flow of apparatus is insufficient to meet all inspiratory requirements • High flow Gas flow of the apparatus is sufficient to meet all inspiratory requirements • Reservoir Stores a reserve volume that equals or exceeds the patient tidal volume

9. According to performance • Fixed FiO2 If the system provides all the patient’s inspired gas • Variable FiO2 If the system provides only some of the inspired gas, the patient draws the remaining from surrounding air

10. Variable performance devices No capacity Nasal catheters Nasal cannulae Small capacity Face masks Large capacity device Mask with bag Fixed performance devices HAFOE systems Anaesthesia circuits Ventilators According to performance

11. Low flow Nasal cannula Nasal catheter Trans tracheal catheter Reservoir Reservoir cannula Simple mask Partial rebreathing mask Nonrebreathing mask Nonrebreathing circuit High flow Air entrainment mask Air entrainment nebulizer Blending system Enclosure Oxyhood Isolette Tent According to design

12. How to select • Purpose • Patient Age Level of Consciousness Pattern of breathing • Performance of the device

13. Advantages No rebreathing Better tolerated Easy to use Disposable Low cost Disadvantages Flow > 3 L / min not tolerated Gastric distension Drying of mucosa O2 wastage Jet lesion if vents are blocked Unstable Nasal cannula FiO2 range : 0.22 -0.45

14. Patient factors Inspiratory flow rate Duration of inspiration Duration of expiratory pause Minute ventilation Device factors Oxygen flow rate Physical volume Resistance Variable performance devices

15. Home care patients needing long term therapy Low – moderate FiO2 during eating Nasal cannula- Uses

16. Advantages Good stability Disposable Low cost Disadvantages Difficult to insert Change every 8 hrs High flow increases back pressure DNS or polyp may block insertion May provoke swallowing or gagging -aspiration Nasal catheterFiO2: 0.22-0.45

17. Nasal catheter- Uses • 250ml- 8L flow • During bronchoscopy • Longterm care of infants

18. Advantages Lower oxygen cost No skin, nasal irritation Improved compliance Improved exercise tolerance Increased mobility Enchanced image Disadvantages High cost Surgical complication Infection Mucous plugging Lost track Trans tracheal catheter FiO2 0.22-0.35

19. 250ml- 4L Ambulatory patients who need increased mobility Patients who do not accept nasal O2 Trans tracheal catheter -Uses

20. Nasal cannula, catheter

21. Face mask Mask with reservoir bags

22. FiO2- 0.22-0.35 250ml- 4 L /min Advantages Lower O2 cost Increased mobility Less discomfort Disadvantages Unattractive Cumbersome Poor compliance Regularly replace every 3 weeks Reservoir cannula Uses Home care Ambulatory patients

23. Oxymizer reservoir cannula Pendant reservoir cannula

24. Low capacity devices(physical volume adds a dead space) • Rebreathing possible : - Device volume is high - O2 flow is low - Expiratory pause is short • Better tolerated at high flows • At high flows O2 is lost through the vents

25. FiO2 0.35-0.50 5-12 L/ min Advantages Easy to apply Disposable Inexpensive Disadvantages Uncomfortable Must be removed for eating Prevent radiant heat loss Block vomitus Simple face mask

26. Simple face mask Tracheostomy mask

27. Conventional face mask with CO2 sampling port Bevel tip sample tube in the mid dome of a medium concentration oxygen mask Monitor respiration Capnoxygen mask

28. Partial rebreathing mask 6-10L /min FiO2 0.35-0.60 Has no valves Inspiration –O2 flows to mask and patient Expiration – source O2 and expired gas enters the bag Non rebreathing mask 6-10L/min FiO2 0.55-0.70 Has 2 one way valves Insp- insp valve opens provides O2 to patient Exp- exp valve opens divert exp gas to atmosphere Large air leaks

29. Large capacity devices • A reservoir bag is attached to the mask • O2 can accumulate throughout the respiratory cycle • Rebreathing is possible • Tight fit • Flows which prevent collapse of bag during inspiration • FIO2 = 0.6 – 0.9

30. Non rebreathing mask Most useful in Emergency department 12-15L/min Adult , paeds size Coloured float that rises and falls when pressure and flow changes Housing is designed to rotate 3600 to allow monitoring in all positions Respi-check mask Breakell A et al Emerg Med J. 2001 Sep;18(5):366-9

31. Bag and mask resuscitator

32. Non rebreathing circuits • Reservoir device • 3 times minute ventilation • Fixed FiO2 • Blending system to premix air O2 • Warmed, humidified by servo controlled heated humidifier FiO2 range 0.21-1

33. High air flow oxygen enrichment • Air entrainment by an oxygen venturi • Air entrainment nebulizer The ventimask • Air entrainment devices function as true high flow system only at low FiO2 • If output flow decreases below the patient’s inspiratory flow, air dilution occurs and FiO2 becomes variable

34. Streaming fluid regains the pressure, much higher than that at the constriction, if the tube distal to the constriction opens very gradually Venturi This function is lost if the angle of the cone is > 15º

35. The ventimask… • Operating principle- venturi !! ? • Shearing effect • Low to moderate FiO2 0.24-0.40 • Depends on -size of the nozzle -Oxygen velocity -Size of air entrainment port -Downstream flow resistance

36. 24% blue 28% white 35% yellow 40% red 60% green The Ventimask…

37. Air oxygen ratio • MAGIC BOX 20 30 70 30/ 50 = 0.6:1 100 50

38. 2-10 L/min oxygen flow Equalent or greater FiO2 than venturi mask Oxy arm Headset baffled cup diffuser

39. Oxyarm- Advantages • Patient can talk • Minimal contact-Routine nursing care • No clastrophobia Lack of facial contact Unhindered line of sight • Odorless and latex free • Capnography is possible Ling E et al Can J Anaesth. 2002 Mar;49(3):297-301.

40. 10-15L/min input Output flow atleast 60L/min Advantages Temperature control Extra humidification Disadvantages FiO2 <0.28 or >0.4 not ensured Varies with back pressure High infection rate Air entrainment nebulizer • Fixed FiO2 (0.28-1)

41. Air entrainment nebulizer… • Ways to assess whether air entrainment nebulizer meets patient’s needs -Mist output at the expiratory side of the ‘T’ tube through out inspiration -Compare it with patient’s peak inspiratory flow

42. Should provide output flow of atleast 60L/min Advantage Full range of FiO2 Disadvantage Requires 50psi air +O2 Blender failure Inaccuracy is common Blending system Fixed FiO2 (0.21-1)

43. Face tent FiO2 -0.40-0.50 • 12-15L/min • Variable FiO2 Advantage • Provides concurrent aerosol therapy • Disadvantages • Expensive • Cumbersome • Requires cooling • Difficult to clean, disinfect • Limits patient mobility • Fire hazard

44. Oxygen hood Minimum flow 7 L / min to prevent rebreathing • FiO2 0.21-1

45. Oxygen therapy in incubator • A venturi is used to add oxygen to the chamber • Scavenging mechanism in built → air changes • Humidification possible • Temperature maintained • Multiple access ports for nursing • Infant can be transported

46. Evaluation of therapy • Respiratory rate • Work of breathing • PO2 • Blood pressure • Pulse rate • Perfusion • Level of consciousness

47. Protocol for titration of oxygen therapy CLINICAL SIGNS OF HYPOXEMIA NO YES DELAY O2 TITRATION SEE O2 ALGORITHM IS SPO2/ O2 SAT≥92% YES NO IS SPO2 <92% ↓ O2 TO MAINTAIN SPO2 ≥92%, RECHECK NO YES ↑O2 TO GET SPO2 ≥92% , RECHECK CONT PRESENT O2 THERAPY

48. DOES PT REQUIRE O2 TO MAINTAIN SPO2 ≥92% NO YES CHECK SPO2 ON NEXT SHIFT(WHILE AWAKE) IS SPO2≥92% ON ROOM AIR? NO YES RECHECK ON NEXT SHIFT (WHILE AWAKE) D/C O2 YES NO IS SPO2≥92% ON ROOM AIR? RESTART O2 MAINTAIN SPO2≥92% RECHECK D/C O2

49. Toxicity of normobaric oxygen • Physiology – Vasoconstriction • V/Q changes ↓ buffering capacity of blood CO2 narcosis Eye - retrolental fibroplasia • Lungs - acute and chronic toxicity

50. Modes of Mechanical Ventilation