Evaluating patients with suspected hypoxic respiratory failure 2

2. Oxygen - there is a problem Published audits have shown Doctors and nurses have a poor understanding of how oxygen should be used Oxygen is often given without any prescription If there is a prescription, it is unusual for the patient to receive what is specified on the prescription

3. Oxygen - there was a disagreement Chest Physicians Intensivists / Anaesthetists Emergency Medicine / A&E clinicians Ambulance teams

4. Time to do something! The British Thoracic Society, together with 21 other Societies and Colleges has produced a multi-discipline Guideline for emergency oxygen use. This Guideline covers most aspects of emergency oxygen use in pre-hospital care and in emergency hospital care for adults (excludes NIV and IPPV)

6. Basis of the BTS guideline Prescribing by target oxygen saturation Keep it normal/near-normal for all patients except pre-defined groups who are at risk from hypercapnic respiratory failure

7. What is normal and what is dangerous?

8. Normal Range for Oxygen saturation

9. Effects of sudden hypoxia(e.g Removal of oxygen mask at altitude or in a pressure chamber) Impaired mental function; Mean onset at SaO2 64% No evidence of impairment above 84% saturation Loss of consciousness at mean saturation of 56% Test Pilots in decompression chambers do not experience breathlessness when the oxygen tension is lowered Akero A et al Eur Respir J. 2005 ;25:725-30 Cottrell JJ et al Aviat Space Environ Med. 1995 ;66:126-30 Hoffman C, et al. Am J Physiol 1946, 145, 685-692

10. What happens at 9,000 metres (approximately 29,000 feet) � it depends

11. Why is oxygen used?

12. Aims of emergency oxygen therapy  To correct or prevent potentially harmful hypoxaemia To alleviate breathlessness (only if hypoxaemic) Oxygen has no effect on breathlessness if the oxygen saturation is normal

13. Fallacies regarding Oxygen Therapy �Routine administration of supplemental oxygen is useful, harmless and clinically indicated� Little increase in oxygen-carrying capacity Renders pulse oximetry worthless as a measure of ventilation May prevent early diagnosis & specific treatment of hypoventilation This guideline only recommends supplemental oxygen when SpO2 is below the target range or in critical illness or CO Poisoning John B Downs MD Respiratory care 2003;48:611-20

14. Oxygen therapy is only one element of resuscitation of a critically ill patient The oxygen carrying power of blood may be increased by Safeguarding the airway Enhancing circulating volume Correcting severe anaemia Enhancing cardiac output Avoiding/Reversing Respiratory Depressants Increasing Fraction of Inspired Oxygen (FIO2) Establish the reason for Hypoxia and treat the underlying cause (e.g Bronchospasm, LVF etc) Patient may need, CPAP or NIV or Invasive ventilation

15. Defining safe lower and upper limits of oxygen saturation

16. What is the minimum arterial oxygen level recommended in acute illness Target oxygen Saturation Critical care consensus guidelines Minimum 90% Surviving sepsis campaign Aim at 88-95% But these patients have intensive levels of nursing & monitoring This guideline recommends a minimum of 94% for most patients � combines what is near normal and what is safe

17. Exposure to high concentrations of oxygen may be harmful Absorption Atelectasis even at FIO2 30-50% Intrapulmonary shunting Post-operative hypoxaemia (on return to room air) Risk to COPD patients Coronary vasoconstriction Increased Systemic Vascular Resistance Reduced Cardiac Index Possible reperfusion injury post MI Hyperoxaemia was associated with INCREASED mortality in survivors of cardiac arrest Oxygen therapy INCREASED mortality in non-hypoxic patients with mild-moderate stroke This guideline recommends an upper limit of 98% for most patients. Combination of what is normal and safe

18. Exposure to high concentrations of oxygen may be harmful Absorption Atelectasis even at FIO2 30-50%1 Intrapulmonary shunting1 Post-operative hypoxaemia (on return to room air)1 Risk to COPD patients2 Coronary vasoconstriction3 Increased Systemic Vascular Resistance3 Reduced Cardiac Index after coronary bypass surgery4 Possible reperfusion injury post Myocardial Infarction5 Oxygen therapy increased mortality in non-hypoxic patients with mild-moderate stroke6 Hyperoxaemia was associated with increased mortality in survivors of cardiac arrest7 This guideline recommends an upper limit of 98% for most patients. Combination of what is normal and safe

19. Some patients are at risk of CO2 retention and acidosis if given high dose oxygen Chronic hypoxic lung disease COPD Severe Chronic Asthma Bronchiectasis / CF Chest wall disease Kyphoscoliosis Thoracoplasty Neuromuscular disease Obesity hypoventilation

20. What is a safe lower Oxygen level in acute COPD?  In acute COPD pO2 above 6.7 kPa or 50 mm Hg will prevent death SaO2 above about 85% (Keep SpO2 =88% to allow for oximeter error and ensure PaO2 >85% )

21. What is a safe upper limit of oxygen target range in acute COPD ? 47% of 982 patients with exacerbation of COPD were hypercapnic on arrival in hospital 20% had Respiratory Acidosis (pH < 7.35) 5% had pH < 7.25 (and were likely to need ICU care) Most hypercapnic patients with pO2 > 10 kPa were acidotic (equivalent to oxygen saturation of above ~ 92%) i.e. They had been given too much oxygen RECOMMENDED UPPER LIMITS Keep PaO2 below 10 kPa and keep SpO2 = 92% in acute COPD

22. Recommended target saturations The target ranges are a consensus agreement by the guidelines group and the endorsing colleges and societies Rationale for the target saturations is combination of what is normal and what is safe Most patients 94 - 98% Risk of hypercapnic respiratory failure 88 � 92%* *Or patient specific saturation on Alert Card

23. Using Target Saturation Scheme O2 prescribed by target saturation (like an Insulin �BM sliding-scale chart�) Oxygen delivery device and flow administered and changed if necessary to keep the SpO2 in the target range Target oxygen saturation prescription integrated into patient drug chart and monitoring

24. Safeguarding patients at risk of type 2 respiratory failure Lower target saturation range for these patients (88-92%) Education of patients and health care workers Use of controlled oxygen via Venturi masks Use of oxygen alert cards Issue of personal Venturi masks to high-risk patients

26. Oxygen Alert Cards and Venturi masks can avoid hypercapnic respiratory failure associated with high flow oxygen masks Oxygen alert card (and a Venturi mask) given to patients admitted with hypercapnic acidosis with a PO2 > 10kPa. Patients instructed to show these to ambulance and A&E staff. After introduction of alert cards Use of Venturi mask: 63% in Ambulance 94% in A&E Gooptu B, Ward L, Davison A et al. Oxygen alert cards and controlled oxygen masks: Emerg Med J 2006; 23:636-8

27. Danger of Rebound Hypoxaemia If you find a patient who is severely hypercapnic due to excessive oxygen therapy (e.g pH 7.23 Pa CO2 13 PaO2 35) Do NOT stop oxygen therapy abruptly. The PaCO2 is very high which causes low PAO2 due to the Alveolar Gas Equation (PAO2 � PIO2 �PACO2/RER ) If suddenly changed to air --? PAO2 = 20 � 16.2 = 4 kPa ( PaO2 will be even lower) It is safest to step down to 35% oxygen if the patient is fully alert or call your Critical Care team arrive to provide mechanical ventilation if the patient is drowsy.

28. Prescribing Oxygen

30. Clinician (usually a doctor) prescribes oxygen by circling the desired oxygen saturation target range Staff use appropriate device and flow rates in order to maintain saturation within the target range

31. Oxygen use in palliative care Most breathlessness in cancer patients is caused by specific issues such as airflow obstruction, infections or pleural effusions and the main issue is to treat the cause Oxygen has been shown to relieve dyspnoea in hypoxic cancer patients Morphine and Midazolam may also relieve breathlessness

32. Devices

33. Non re-breathing Reservoir Mask. Critical illness / Trauma patients. Post-cardiac or respiratory arrest. Delivers O2 concentrations between 60 & 80% or above Effective for short term treatment.

34. Nasal Cannulae Recommended in the Guideline as suitable for most patients with both type I and II respiratory failure. 2-6L/min gives approx 24-50% FIO2 FIO2 depends on oxygen flow rate and patient�s minute volume and inspiratory flow and pattern of breathing. Comfortable and easily tolerated No re-breathing Low cost product Preferred by patients (Vs simple mask)

35. Simple face mask (Medium concentration, variable performance) Used for patients with type I respiratory failure. Delivers variable O2 concentration between 35% & 60%. Low cost product. Flow 5-10 L/min Flow must be at least 5 L/min to avoid CO2 build up and resistance to breathing (although packaging may say 2-10L)

38. Operation of Venturi valve

39. Oxygen Flow MeterThe centre of the ball indicates the correct flow rate.

40. What device and flow rate should you use in each situation?

41. Standard Oxygen Therapy 1960s-2008

42. Oxygen therapy 2008 onwards

43. Many patients need high-dose oxygen to normalize saturation Severe Pneumonia Severe LVF Major Trauma Sepsis and Shock Major atelectasis Pulmonary Embolism Lung Fibrosis Etc etc etc

44. BTS Recommendations

49. Titrating Oxygen up and down. This table below shows APPROXIMATE conversion values. Venturi 24% (blue) 2-4l/min OR Nasal specs 1L Venturi 28% (white) 4-6 l/min OR Nasal specs 2L Venturi 35% (yellow) 8-10l/min OR Nasal spec 4L Venturi 40% (red)10-12l/min OR Simple face mask 5-6L/min Venturi 60% (green) 15l/min OR Simple face mask 7-10L/min Reservoir mask at 15L oxygen flow seek medical advice I f reservoir mask required seek senior medical Input immediately

50. Monitoring patients

52. From the BTS Emergency Oxygen Guideline To the patient  Guideline agreed by the whole UK medical, nursing and AHP community (endorsed by 21 Colleges and Societies) Medical and Nurse/Physio Champions in every Hospital Trust New prescription charts and monitoring charts in every hospital Training packages on BTS website NPSA Rapid Response Report September 2009 Audit tools on BTS website www.brit-thoracic.org.uk

53. Summary  Prescribe oxygen to a target saturation for each group of patients 94 - 98% for most adult patients 88 - 92% if risk of hypercapnia (or patient-specific target on alert card) Administer oxygen to achieve target saturation Monitor oxygen saturation and keep in target range Taper oxygen dose and stop when stable Audit your practice All information on www.brit-thoracic.org.uk