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1. RESOURCES for OXYGEN and a COMPREHENSIVE CRITICAL CARE STRATEGY Dr Simon MardelOBE MSc DTM&H FFARCSI FRCSEdConsultant in Emergency Medicine Leicester UK & Short Term Consultant WHO 98% Isolation Ward Kenema Government Hospital Sierra Leone Simulation training for H5N1 Republic of Moldova Abulfaz Karayev Children Hospital Azerbaijan

2. Any country where demand for timely critical care exceeds capacity Population exposed to Influenza A (H1N1) Co-morbidities No co-morbidities • subgroup that develops respiratory failure(or other organ failure) will have a much greater mortality if: • Co-morbidities • Late referral • Poor supportive care • Reduced access to advanced care Infected Hospitalised Respiratory failure

3. Contents • Why measure oxygen saturation? • How to correct hypoxaemia more effectively • How to rapidly increase availability (surge capacity)

4. Why measure oxygen saturation? • How to correct hypoxaemia more effectively • How to rapidly increase availability

5. Hypoxaemia • Hypoxaemia means low oxygen levels in the blood. It is a life-threatening condition that occurs frequently in pneumonia • Even the best combinations of clinical signs commonly misdiagnose hypoxaemia • The best way to detect and monitor hypoxaemia is with pulse oximetry. Oximetry is accurate, simple, non-invasive, and cost efficient.

6. Hypoxaemia - additive relationships A-a* gradient in viral pneumonia increases rapidly to below hypoxic threhold + A-a gradient is already significant in obesity or most pre-existing lung diseases + Alveolar oxygen reduced by altitude - Alveolar oxygen increased by increasing inspired oxygen concentration *Aleveolar-arterial gradient

7. 98 Examples of pulse oximeters The normal range of Sp02 at sea level is 94 - 100% An SpO2<90% is considered by most clinicians as an appropriate indication for giving oxygen 99

8. 80 Low Oxygen saturations e.g. SaO2 = 80% What does this number really mean? The answer involves the “S” Sigmoid shape of THE OXYGEN HAEMOGLOBIN DISSOCIATION CURVE

9. Early Warning Score Charts

10. Comprehensive Critical Care Strategy - Levels of care the most critical increase in surge capacity

11. Why measure oxygen saturation? • How to correct hypoxaemia more effectively 3. How to rapidly increase availability

12. “SaO2 should be maintained over 90%”“Patients with severe hypoxia need high flow oxygen (e.g. 10 l/min) delivered by face mask”.

13. Oxygen treatment - what flow rate? - what device? high flow rates are necessary for severe hypoxaemia e.g. 10-15 litres per minute. The reason involves another graph !

14. When an adult breathes in, there is a peak inspiratory flow of around 30 litres per minute Can you guess the peak flow rate during INSPIRATION ? inspiration inspiration 30 Flow rate l/min expiration inspiration pause pause pause expiration expiration

15. With pneumonia the breathing rate and the peak inspiratory flow rates increase 40 Flow rate of expiration inspiration Depending on the patient’s respiratory rate and depth, and flow of oxygen, a variable concentration is administered

16. Mexico H1N1: Use of devices and monitoring to maintain SaO2

17. Nasal prongs (nasal cannulae) Nasal Prongs are a device that ends in two short tapered tubes (about 1 cm in length) designed to lie just within the nostrils. “Nasal cannulae do not permit high flow rates of oxygen and are only effective for management of mild hypoxemia”.

21. Example of “non re-breathing” or “100% mask”

26. Poor compliance! Some adults will not tolerate oxygen masks well complaining of claustrophobia, the smell and a dry throat. Often encouragement improves compliance but since many hypoxic patients are restless all confused and this may be a particular problem

27. “Some patients may experience difficulties with compliance and require the close involvement of nursing staff (and parents of children)”.

28. Lessons from H5N1 In Azerbaijan 2 children with severe H5N1 pneumonia were successfully treated by this paediatric hospital team. The children required high flow oxygen by face mask and did not require ventilation.

29. fast pulselow SaO2fast breathing Case 2. Age 15y hypoxia severe Case 1. Age 17y hypoxia severe and prolonged Case “u” 15y Female

30. “SaO2 should be maintained over 90%” who else helped the child with more severe hypoxaemia to receive oxygen by mask continuously –initially at 8 l/min ? The mother was shown her own SaO2(normal) and her childs SaO2, and how the SaO2 increased when her child received high flow oxygen by face mask. She then helped her child to comply with 7 days of oxygen treatment that was required

31. O2 is part of the chain of survival Hypoxia!Detect & Treat In everylocation

32. Why measure oxygen saturation? • How to correct hypoxaemia more effectively • How to rapidly increase availability

33. “Output from oxygen generators can vary in concentration and flow rate, and may be insufficient for correcting severe hypoxemia.”

36. “If piped oxygen is not available in the medical ward, a supply of large cylinders will be needed.”

37. Infection control “hazards” E.g. A heavily contaminated bubble humidifier in use on a ward DO NOT USE THESE FOR SIMPLE FACE MASK DELIVERY!

38. Oxygen – practical 8-10 litres per minute = 600 litres per hour = 14,400 litres per day In Azerbaijan we used 18 large size cylinders to treat 2 cases! Approx. 10USD per cylinder refill

39. (In the absence of medical gases, industrial oxygen for face mask delivery would suffice if certain precautions are observed) “WHO has included oxygen in the Essential Medicines list since 1979 but it is still not widely available in some countries. If medical oxygen is not available, then industrial oxygen can be used (e.g. delivered by face mask) provided it conforms with national guidelines.”

40. ..\My Documents\cpmpaq desktop 13 march2008\pdf files to be sorted and refs\ITU pyramid critical care.jpg

41. END TALK • THE FOLLOWING SLIDES MAY RESPOND TO QUESTIONS FROM AUDIENCE

42. DO NOT OVERHYDRATE • Use oral fluids if the GI tract is unaffected and not in shock • Uncertainty about “running patients dry” • Some patients arrive in ITU in Positive fluid balance. • Many Intensivists report improvement in hypoxia by use of diuretics or restricting fluids • Some intensivists allow creatinine to rise a little if this avoids worsening the hypoxia.

43. The Intensivists Dilemma TRY TO AVOID IPPV • Patient might recover with simple measures BUT • Risks from hyppoxia • Patient may deteriorate quickly • Late IPPV as rescue – difficult to use lung protective strategy v. EARLY IPPV • Allows lung protective strategy • Avoids crisis from sudden deterioration BUT • Risks e.g. VAP* and Resource • Intense • Ventilator Associated Pneumonia risk proportional to days on IPPV

44. Human avian influenza (AI) caused by A (H5N1) has a high case fatality rate of 61%, and is highest between ages 10-19 years, even where intensive care facilities have been used.. Lessons from H5N1 Many patients arrive at these facilities having suffered prolonged uncorrected hypoxaemia as a result of viral pneumonia. Early diagnosis is difficult as symptoms are initially indistinguishable from common illnesses, as pneumonia develops the patient deteriorates rapidly and it is at this point that most patients present to a reference hospital.

45. Clinical characteristics of ten H5N1 patients on Admission and their final outcome* Yellow highlights the higher oxygen saturations on admission of the only 2 survivors Pink highlights the case numbers with chest radiographs published (next 3 slides) Case Number The 8 patients who died received mechnical ventilation during the first 48hrs after admission, their oxygen saturations are very low, especially as they are receiving oxygen therapy *avian influenza A(H5N1) in 10 patients in Vietnam N Engl J Med 350;12 ,18 March 2004. (Data from tables 2 and 3).

46. Small changes in SpO2 between 90 to 100% --- Below SpO2 of 90% Curve here is relatively steep Curve here is relatively flat Small falls in PaO2 --- --- may result inmuch larger falls in SpO2! --- reflect large changes in PaO2! Below SpO2 of 90%

47. Peak Inspiratory Flow Rate of e.g. 30 litres per minute Are you surprised at how high this is? Remember we measure peak expiratory flow rates in asthma – and values are often 100 – 500 litres per minute !

48. Venturi masks or High Airflow Oxygen Enrichment Masks Relatively high flows of oxygen passing across a narrow orifice allow entrainment of additional room air to the mask to meet the inspiratory flow of the patient. The masks deliver a fixed amount of oxygen that can be prescribed – common percentages include 24%, and 28%, 35% and 60%. entrained room air entrained room air

49. Venturi masks or High Airflow Oxygen Enrichment Masks Entrainment of room air causes high flow over 30 litres per min ! Noisy and uncomfortable for patients. These devices deliberately dilute the oxygen and ARE NOT indicated for correcting hypoxia except in certain conditions where inspired higher oxygen should be avoided. The very high flow of venturi devices raised concerns about aerosol spread during SARS. entrained room air

50. Industrial oxygen will have to contribute to any massive increase in surge capacity