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- 1. The management ofsevere hypoxaemic respiratory failure in critical care Simon Baudouin Senior Lecturer in Critical Care University of Newcastle
- 2. Conventional definitions ◦Type 1 PaO2 < 8 kPa on air ◦ Type 2 PaO2 < 8 kPa on air & PaCo2 > 6 kPa Not helpful! ◦ Ultimately all severely ill patients become hypercapnic without intervention Acute Chronic Acute on chronic Reach ITU v intubate in EAU Respiratory failure
- 3. Hypoxaemia –V/Q mismatch & shunt Hypercapnia ◦ Hypoventilation ◦ Increase in deadspace ventilation ◦ V/Q mismatch Respiratory Failure - pathophysiology
- 4. The magnitude ofCOPD in the UK Uk National COPD audit 2003; Thorax 2006;61:837-842 234 UK acute hospitals 40 consecutive acute COPD admissions 7259 patients 90 day readmission rate 31.4%! Inpatient 90 day 0 10 20 30 40 50 60 70 80 90 100 7.4 15.3 % mortality
- 5. The magnitude ofCOPD in the UK 16-47% hypercapnia Half will need ventilatory support - Plant et al, Thorax, 2000; 55: 550-554 - 1 year survey in Leeds 983 admissions 2.2% ICU admissions 73% hospital mortality in ICU admissions 70 NIV patients/year/250,000 population
- 6. Aetiology of Respiratory failure Explanation of hypoxaemia and hypercapnia Multiple inert gas elimination Broad V/Q distribution Hypercapnia = ventilation to under-perfused units Hypoxaemia = shunting Respiratory muscle fatigue? Altered central drive?
- 7. Oxygen treatment Hypoxaemiais usually correctable with low flow O2 The optimal target SaO2 is unknown > 90% - O2 dissociation curve > 85% (ARDS net) One small study (n = 36) 6.6hPa v 9.0 hPa - no difference (underpowered) High flow O2 will worsen Hypercapnia Change to controlled O2 will reduce PaCO2
- 9. NIV in acuteexacerbations of COAD pH < or = 7.35 not acidotic acidotic 0 2 4 6 8 10 12 14 Mortality %
- 10. NIV Standard 0 5 10 15 20 25 30 NIV Standard 0 5 10 15 20 Randomisedcontrolled trials in NIV Early use of non-invasive ventilation for acute exacerbations of chronic obstructive pulmonary disease on general respiratory wards: a multicentre, randomised, controlled trial. Plant et al. Lancet, 2000; 355: 1931-35 • 14 UK Hospitals • n = 236 Mortality p = 0.05 Intubation p = 0.02
- 11. Cochrane review &meta-analysisfor COAD Relative risk Mortality 0.41 Intubation 0.42 Complications 0.32 LOS -3.2 days BMJ 2003;326:185-190 Typical UK hospital will avoid 3-9 ICU admissions/year Save £12,000- 53,000
- 12. NIV in A&E “Theuse of non-invasive positive pressure ventilation in the emergency department” RCT 6/12 study NIV vs. conventional support 87 screened - 34 “immediate” intubation - 27 entered - 11 conventional - 16 NIV Wood. Chest, 1998; 113: 1339-46
- 13. • Time to intubationStandard 4.8 hrs NIV 26.0 hrs NIV in A&E standard NIV 0 20 40 60 80 100 intubated(%) standard NIV 0 20 40 60 80 100 mortality(%)
- 14. Critical Care forAll? • Should all patients receive NIV in a critical care area? • No RCTs • Majority of trials are in Critical Care areas Brocha rd Plant 0 5 10 15 20 % mortality ICU Ward 0 20 40 60 80 100 % intubated Plant
- 16. NIV in exacerbationsof COAD Recommendations of the COAD and NIV Standards of Care sub-committees of the British Thoracic Society, RCP & Modernisation Agency Every acute admissions unit should have an NIV service
- 17. Predicting outcome withNIV - Failure rate 7-50% - delay intubation Acidosis APACHE II - Indications for HDU admission For intubation if NIV fails Initial pH 7.25 or less Worsening pH on NIV
- 18. Indications for intubation Patient choice Failure of NIV Usually obvious clinically ◦ Fatigued “awful looking” patient ◦ Worsening hypercapnia and LOC ◦ A&E arrest/peri-arrest situation
- 19. Longer-term issues Patient/ventilatorinteractions Weaning Tracheostomy Nutrition The “unweanable” patient
- 20. Weaning Rapid trialof extubation (onto NIV) Early tracheostomy Regular Sedation cessation Weaning protocols A little progress every day!
- 21. Weaning with NIV N=43 (most with COAD failed wean for 3 days Shorter ICU & hospital LOS Less need for tracheostomy Control NIV 0 10 20 30 40 50 60 70 80 90 % survival 90 day survival Am J Respir Crit Care Med 2003;168:70-6
- 22. Longer term outcomein COPD hospital 1 year 2 year 0 5 10 15 20 25 30 35 40 45 50 mortality %
- 23. Summary COPD admissionswill increase NIV is effective in both survival and prevention of intubation Outcome of ventilation in COPD is no worse than in other conditions Patient choice and informed decisions
- 24. Previously fit24 year old women First pregnancy No problems until week 35 “Cough and cold” “Shivery” Increasingly breathless over 24 hours Brought to maternity ward by husband Clearly very unwell SaO2 air 79% RR 35/min Crackles ++ Foetus alive Critical Care outreach called The new 21st century critical care
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- 26. Early corticosteroids insevere influenza A/H1N1 pneumonia and acute respiratory distress syndrome. Am J Respir Crit Care Med. 2011 May 1;183(9):1200-6. French national registry – no benefit; possible early harm Corticosteroids in severe H1N1pneumonia European SICM database Cox analysis no benefit from steroids
- 27. Critical Careobstetric intensivist Separate the two patients Foetus is viable Ventilation for the Mother is inevitable Experience from other units Urgent Caesarean section Ventilated with Critical Care ventilator during section Healthy girl delivered Mother transferred to critical care unit Delivery?
- 28. Invasive Mechanical Ventilation Substitutefor the respiratory muscle pump Complex multi- functional machines Efficacy established during polio epidemics 1960s Led to development of modern, centralised critical care services
- 29. Ventilator-induced lung injury 10ml/Kg 30 ml/Kg 0 2 4 6 8 10 12 14 Broncho-pulmonary dysplasia Well + Tierney 1974 - rats ventilated with peak airway pressures 45 cm H2O developed pulmonary oedema Carlton 1990 - Lung overexpansion increases lymph flow in lambs Lymph flow ml/Kg
- 30. Ventilation with lowertidal volumes as compared with traditional volumes for acute lung injury and the acute respiratory distress syndrome 0 10 20 30 40 60 80 180 0 20 40 60 80 100 120 Conventional Protection Days Survival (5) Mortality at 180 days Protection 31.0% Conventional 39.8% P = 0.007
- 31. Lung compartments inARDS Normal lung Partial collapse/flooding Complete collapse recruitable
- 32. Does PEEP recruitlung in ARDS? 5 cm PEEP 5 cm PEEP
- 33. Fluid management inARDS N = 1000 60 day mortality Liberal v conservative fluid liberal conservative -2000 0 2000 4000 6000 8000 Fluid balance
- 34. Fluid management inARDS Improved oxygenation Increased ventilator free days No increase in shock or dialysis liberal conservative 0 20 40 60 80 100 60 day Mortality %
- 35. Lower PEEP HigherPEEP 0 20 40 60 80 100 Percentage mortality N = 549 How much PEEP? Higher versus lower PEEP in patients with ARDS New Engl J Med 2004;351:327-336 Lower PEEP = 8 cm H2O Higher PEEP = 13 cm H2O
- 36. Often improvesoxygenation Proposed mechanisms - recruitment of dorsal collapsed lung units - improved respiratory mechanics - increased secretion drainage - decreased injury from mechanical forces Prone positioning in ARDS
- 37. Gattinoni 2001 Guerin2004 0 10 20 30 40 50 60 70 80 90 100 Prone Supine Percentage mortality Prone positioning in ARDS N=304 N=791
- 38. Initial improvementin PaO2/SaO2 to 90% Gradual fall to SaO2 84% CXR – no mechanical cause 07:00
- 39. Rescue =desperation Rescue = no high grade evidence Rescue = risks as well as possible benefits ◦ Oscillator ventilation ◦ ECMO “Rescue therapy in ARDS”
- 40. Rate 60– 100 bpm TV below anatomic deadspace Alveoalar derecruitment & overdistention limited High frequency ventilation
- 41. • Large, multi-centreRCT • Conventional v high frequency ventilation • Complete recruitment 2012 • Over 800 patients
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- 44. Outcome in1 ECMO centre (Glenfields) Protocolised care Experienced experts Average outcome in 92 conventional centres 11 referral centres Non protocolised care Variable experience Variable clinical cover/team What is the Cesar trial comparing
- 45. Hypoxaemia isthe greatest immediate threat Severe oxygen induced hypercapnia is rare Oxygen induced hypercapnia only occurs in chronic respiratory failure Previously well patients with hypercapnia are severely ill Hypercapnia does not equate to COPD Respiratory failure
Editor's Notes
- #42 The iLA-system. A passive femoro-femoral shunt flow generated by the arterial pressure passes a lung assist device (in the box), in which an oxygen flow is inserted. Reproduced with permission from Zimmerman and colleagues.47 © The Board of Management and Trustees of the British Journal of Anaesthesia 2005. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org.