Used to treat tissue hypoxia Improve oxygen supply Reduce the work of breathing Potential to improve medical outcomes and save lives if used

Transcription

1 Used to treat tissue hypoxia Improve oxygen supply Reduce the work of breathing Potential to improve medical outcomes and save lives if used appropriately Can cause harm if used inappropriately

2 Main indication is the presence of tissue hypoxia Because of 1. Arterial hypoxaemia (inadequate oxygen content) 2. Failure of oxygen- haemoglobin transport system

3 Defined as oxygen saturation < 90% or arterial tension po2 < 60 mmhg Caused by Impaired gas exchange in the lung Alveolar hypoventilation Shunt that allows venous blood into the arterial circulation An arterial blood gas helps discriminate these possibilities

4 Occurs because of the failure of the Oxygen-haemoglobin transport system 1. Reduced oxygen carrying capacity in the blood e.g. anaemia, carbon monoxide poisoning 2. Reduced tissue perfusion e.g. shock

5 No evidence of benefit in acute coronary syndrome or stroke Some potential for harm Oxygen causes coronary vasoconstriction and reduces coronary blood flow Associated with reduced survival in minor and moderate stroke Not indicated in normoxic patients with drug overdoses or metabolic acidosis

6 Paco2 during oxygen administration as a function of Paco2 before oxygen treatment. Rodrigo G J et al. Chest 2003;124: by American College of Chest Physicians

7 Acute exacerbation of COPD is common May present with hypoxia May have chronic elevation of CO2 (>45mmHg) Natural tendency is to relieve hypoxia But oxygen can increase CO2 and reduce ph Acute ventilatory failure is notorious complication defined: hypercapnia and acidaemia

8 Chronic ventilatory failure Acute exacerbations of COPD Rare in stable COPD Obstructive sleep apnoea Obesity hypoventilation syndrome Neuromuscular disease, kyphoscoliosis?others Degree of hypoxia at presentation is better predictor than initial hypercapnia

9 Previous acute ventilatory failure on oxygen CO2 >45mmHg, ph <7.35 and O2 >70mmHg (spontaneous ventilation on supplemental inspired O2) Chronic ventilatory failure(any inspired O2) CO2 >45mmHg with COPD, OSA, Central Sleep Apnea, Obesity Hypoventilation Syndrome Previous acute ventilatory failure ph<7.35 and CO2 >45

10 History incomplete or unavailable Old clinical notes not available Arterial blood gases not feasible or available GCS reduced

11 Oxygen saturation should be monitored with pulse oximetry at least as frequently as other vital signs Clearly documented with inspired oxygen concentration

12 88-92% for all patients with or at risk or hypercapnic respiratory failure 94-98% for all other patients Special considerations for some poisons e.g. carbon monoxide, paraquat, bleomycin

13 Prevention of acute respiratory failure caused by excessive supplemental oxygen Minimise risk of acute ventilatory failure/respiratory acidosis Identify and manage acute ventilatory failure Identify population at risk Controlled oxygen therapy Reassess and titrate O2 to target saturation

14 PLUS any one of the following? Chronic lung disease e.g.: COPD (or suspected) Obesity (visual assessment) Home O 2 or CPAP/Bi-level PAP GCS <15 O 2 Alert- emr alert or Caution with O 2 card Neuromuscular disorder

15 obp < 100 mmhg systolic otrauma call osevere sepsis If any exclusion use another pathway Aim for O 2 saturation 94-98%

16 REDUCE oxygen to 28% o2l/min nasal prongs NP or oventuri mask VM 28%(yellow) If Target sat already achieved on room air or 2 L/min NP or VM <= 28% ocontinue current inspired O 2

17 Oxygen saturation (SpO 2 ) monitoring Venous Blood Gases (VBG) when initial bloods collected Caution with Oxygen stickers in observation + medication charts Drive nebulisers with Air (continue nasal O 2 )

18 On O 2 2 L/min, 28% If O 2 93% change to 1L/min via nasal prongs or 24% VM (blue) repeat step 3 on lower O2 If O % Target achieved Continue current FiO 2 until medical review IfO 2 < 88% Increase O 2 to target SpO2 Urgent Medical review Arterial Blood Gases (ABG) collection

19 On O 2 1 L/min, 24% If O 2 93% change to Remove oxygen (leave on room air) repeat step 3 on room air If O % Target achieved Continue current FiO 2 until medical review check VBG IfO 2 < 88% Increase O 2 to target SpO2 Urgent Medical review Arterial Blood Gases (ABG) collection

20 On room air If O 2 93% Continue on room air until medical review If O % Target achieved Continue on room air until medical review If O 2 < 88% Increase O 2 to target SpO2 Urgent Medical review Arterial Blood Gases (ABG) collection

21 Including any of: Acute breathlessness Decreasing conscious state Oxygen saturation < 88% and falling Oxygen requirements increasing

22 ph>7.35 and pco 2 <45mmHg Not acute ventilatory failure Reduce FiO 2 if possible ph<7.35 or pco 2 > 45mmHg Acute ventilatory failure possible Do ABG

23 CO 2 <45mmHg Not acute ventilatory failure Reduce FiO 2 if possible CO 2 > 45mmHg Acute ventilatory failure possible Check ABG ph and po2

24 po 2 >70 mmhg Reduce FiO 2 if possible po mmhg Target achieved Prescribe current FiO 2 po 2 < 55 mmhg Increase FiO 2 to target SpO2 Senior review Assess response with ABG

25 ph < 7.35 and CO2 > 45 Acute Respiratory Acidosis Consider NIV check GCS Senior review Assess response with ABG

26 Can be managed with Non-Invasive Ventilation (NIV) But increased LOS Morbidity ICU/HDU admissions Hospital resources May correct rapidly when inspired oxygen reduced

27 Doctor prescribe Maintain current inspired oxygen Target current range O 2 saturation Change Clinical Review criteria for SpO 2 to < 88% Document in ED flowchart and notes if CO 2 elevated or Acute Respiratory Acidosis Drive nebulisers with Air (continue nasal O 2)

28 Defined by: CO2 retention acidosis Complications: Narcosis Respiratory failure Death Outcomes: Mechanical ventilation Cardiac arrhythmia ICU admission Subsequent complications

29 Measure O 2 saturations If O 2 sats >92% no O 2 required If sats 85 to 92% 2 litres O 2 nasal prongs, monitor sats and measure ABGs If sats <85% high flow O 2 and titrate to keep sats >92% and measure ABGs [Beasley et al Thorax 2007]

30 No O 2 sats monitor available Suspect severe hypoxaemia Administer 2-3 litres O 2 nasal prongs [Beasley et al Thorax 2007]

31 High concentration oxygen therapy delays recognition of clinical deterioration Low concentration oxygen therapy allows deterioration to be detected earlier, and gives more time to intervene before life- threatening situation develops [Beasley et al Thorax 2007]

32 Flow rates, masks Venturi masks with known inspired O2 NIV with known inspired O2 CPAP Inspired O2 meters CO2 meters

33 Coloured wrist band Clear prescription for O2 in med records identifying acute resp acidosis risk with excessive O2 Warning label on medical record and med chart

34 CAUTION WITH OXYGEN! O2 ALERT TURN CARD OVER FOR INSTRUCTIONS I have Chronic Respiratory Disease My Carbon Dioxide can be raised Do NOT give me High Flow Oxygen! Low Flow Only < 28% Department of Respiratory Medicine Liverpool Hospital

35 Venturi mask 50% O2 back titrate SaO2 to 92% Caution with O2 ID and/or alert on EDIS/PASS Venturi 28% and SaO2 92% ABG s performed within 20 mins of starting supplemental O2

36 Patient receives 1. Caution With Oxygen ID card 2. Venturi O2 mask (28%) 3. Information leaflet 4. Instruction to give ID card and mask to Ambulance Officers or ED staff on presentation In addition Alert in emr Entry in Caution With Oxygen Register