Ventilation in Paediatric ARDS: extrapolate from adult studies? ASMIC 2014 Dr Adrian Plunkett Consultant Paediatric Intensivist Birmingham Children s Hospital, UK
Aims of the presentation Ventilation in pediatric ARDS: extrapolate from adult studies? 1. What is ARDS, and is pediatric ARDS different from adult ARDS? 2. What is the evidence concerning ventilation from the adult studies? 3. Do we apply this apply to children? 4. Do we apply this evidence in adults? 5. Recommended practice specifically for children?
What is ARDS? Acute inflammatory disease of the lung Clinical features first described by Ashbaugh in 1967 Multiple aetiologies or triggers (direct or indirect) Progressive disease with 3 phases: acute (exudative), fibrosis, and recovery Occurs in children and adults
First description of ARDS Ashbaugh, Lancet 1967
First description of ARDS Ashbaugh, Lancet 1967 The clinical pattern includes severe dyspnoea, tachypnoea, cyanosis that is refractory to oxygen therapy, loss of lung compliance, and a diffuse alveolar infiltrate seen on chest X-ray. In view of the similar response of the lung to a variety of stimuli, a common mechanism of injury is postulated. The loss of lung compliance, refractory cyanosis, and microscopic atelectasis point to alveolar instability as a likely source of trouble. The use of positive end-expiratory pressure merely buys time: unless the underlying process can be successfully treated or reversed the prognosis is grave.
Evolving definitions of ARDS: 1967: Acute or ADULT Respiratory Distress Syndrome described 1988: Murray score for lung injury 1994: AECC standardised A(cute)RDS definitions ARDSNet established (1994) Acute onset, severe hypoxemia, widespread bilateral infiltrates on chest radiograph and no evidence of left atrial hypertension 2011: Berlin definition Defines acute (1 week) Levels of severity (ALI term abandoned) Accounts for PEEP
Evolving definitions of ARDS:
Evolving definitions of ARDS:
Evolving definitions of ARDS:
Evolving definitions of ARDS: - what about children?
Evolving definitions of ARDS: - what about children? Lack of trial data for pediatric ARDS Children excluded from many ARDS ventilation studies No paediatric intensivists in either of the consensus conferences Arterial sampling less frequently used in children Pediatric Acute Lung Injury Consensus Conference Aiming to produce consensus criteria for pediatric ARDS defintion
Is pediatric ARDS different from adult ARDS? Children are not little adults Although ARDS occurs in children, there are some unique features of pediatric ARDS: 1. Epidemiology and aetiology: ARDS is less common in children Mortality rate in pediatric ARDS is lower Aetiology (triggers) are similar to adults, but not identical
Epidemiology of pediatric ARDS: Compared with: Incidence of adult ARDS: 17.9-81/100,000/year PED-ALIEN Network Lopez-Fernandez et al Crit Care Med 2012; 40:3238-3245
Mortality in pediatric ARDS: Compared with: Mortality of adult ARDS: 27-45% PED-ALIEN Network Lopez-Fernandez et al Crit Care Med 2012; 40:3238-3245
From: Effect of Prone Positioning on Clinical Outcomes in Children With Acute Lung Injury: A Randomized Controlled Trial JAMA. 2005;294(2):229-237. doi:10.1001/jama.294.2.229 Date of download: 8/16/2014 Copyright 2014 American Medical Association. All rights reserved.
Aetiology of pediatric ARDS: Comparable causes of ARDS in adults: Pneumonia Sepsis Aspiration Trauma But high proportion of viral respiratory illness (RSV) in children (young children). May be different pathophysiology. PED-ALIEN Network Lopez-Fernandez et al Crit Care Med 2012; 40:3238-3245
Is pediatric ARDS different from adult ARDS? 2. Children s lungs are developing and differ from adult lungs: Post-natal maturation of the lung continues well into childhood Important differences between infant and adult lungs: Matrix composition Alveolar structure Angiogenesis Apoptosis Innate immune cell function Increased compliance of chest wall, lower FRC, higher airway resistance Ratio of lung volume to body weight varies throughout childhood Children may be more or less susceptible to VILI
Is pediatric ARDS different from adult ARDS?
Is pediatric ARDS different from adult ARDS? Kornecki et al. Am J Resp Crit Care Med 2005;171:743-752 Rats of 3 maturity levels: Adult Juvenile Infant Mechanical ventilation in vivo and ex vivo Measured metrics of lung injury: Compliance Wet:dry ratio Pro-Inflammatory cytokines Histology
Is pediatric ARDS different from adult ARDS? Juvenile lungs vs. adult lungs (Rats) effects of mechanical ventilation on lung injury: Kornecki et al. Am J Resp Crit Care Med 2005;171:743-752
Is pediatric ARDS different from adult ARDS? Wet:dry ratio of infant vs adult rat lungs after in vivo ventilation Kornecki et al. Am J Resp Crit Care Med 2005;171:743-752
Is pediatric ARDS different from adult ARDS? Kornecki et al. Am J Resp Crit Care Med 2005;171:743-752
Is pediatric ARDS different from adult ARDS? Is senescent ARDS different from young adult ARDS? Old rats more VILI Decreased oxygenation Decreased dry to wet lung ratio Increased lung lavage prtotein Inreased lung IL6 Increased systemic inflammation
Is pediatric ARDS different from adult ARDS? Conflicting data regarding tidal volume in pediatric ARDS: Albuali et al. PCCM 2007 8 (4) Erikson et al. PCCM 2007; 8 (4)
Ventilation in ARDS evidence from adult studies Main evidence-based strategies for mechanical ventilation in adult ARDS: o o o o Lung protective ventilation: o ARDSnet low tidal volume trial (12 vs 6ml/kg) o Mortality reduction in low tidal volume group (31% vs 40%) Open lung strategy o Recent meta-analysis suggests benefit of high PEEP strategy in severe ARDS subgroup o (Briel et al JAMA 2010) Prone positioning: o Recent large study shows mortality benefit in severe ARDS (pf<150), with longer prone time (at least 16 hours) o (Guerin et al, NEJM 2013) HFOV: o o 2 large studies (OSCAR and OSCILLATE) did not show benefit in adult ARDS. Not currently recommended
Ventilation in ARDS evidence from adult studies Low VT ventilation ARDSNet 2000 ARDSNET, NEJM 2000 342
Ventilation in ARDS evidence from adult studies Proning: Geurin et al NEJM 2013 Guerin et al, NEJM 2013 368
Do we apply this to children? High quality evidence to guide ventilation in adult ARDS No evidence-based recommendations to guide pediatric ALI/ARDS ventilation (lack of evidence) Pediatric Intensivists are influenced by the adult evidence Adult evidence and practice creeps in to paediatric practice Do we apply lung-protective ventilation to pediatric ARDS? Does it make a difference?
Do we apply this to children? PCCM 2007
Do we apply this to children? 2 part study by Santschi et al Picture of the theoretical world Vs. Photograph of the real world Part 1: Santshci et al PCCM 2013 International survey of pediatric intensivists Stated practice of ALI / ARDS 3 hypothetical examples High proportion of respondents reported using lung-protective ventilation: Low Vt (5-8ml/kg) Limited peak plateau pressures (<35cmH2O) Permissive hypercapnia and mild hypoxaemia
Do we apply this to children? Santschi et al,pccm 2013
Do we apply this to children? Santschi et al,pccm 2013
Do we apply this to children? Part 2: Santshci et al PCCM 2010 Cross-sectional study of 59 PICUs for 6 x 24 hour periods (2007) Identified 165 children with ALI / ARDS (screened 3823) 25% VT > 10ml/kg Revealed inconsistent ventilation and adjuvant therapy practice 16.4% of patients on HFOV 17.4% ventilated prone Also estimated large number (>60 centres) required for a pediatric ALI / ARDS trial (Likely need 4 years, and 800 patients) Paediatric intensivists tend not to adhere to the adult guidelines, despite reporting that this is their usual practice
Do we apply this to children? Santschi et al PCCM 2010
Do we apply this to adults? Failure to follow evidence-based protocols / guidelines is common in medicine Also true in adult ARDS management Kalhan et al, CCM 2006 identified under-use of lung-protective ventilation strategies (i.e. Low tidal volume) in adult ALI / ARDS patients in a single-centre study: Kalhan et al Crit Care Med 2006; 34(2)
Do we apply this to adults? Survey of patients in US (2003) Variety of medical and surgical conditions Compared actual care with recommended care Approximately 55% of patients received recommended care There are barriers to implementing best practice or EBM to real patients
Do we apply this to adults?
Do we apply this to adults? But: Outcomes continue to improve From: Bernard 2005
What should we do for now with Paeds ARDS Very little trial evidence in children Much guidance is inferred from adult practice Randolph et al CCM 2009
Summary Children develop ARDS, but are there are unique features of childhood ARDS Children are not small adults Epidemiology of ARDS and VILI responses are different in children Research of ARDS in children is lacking, and difficult to carry out in children Much of best practice recommendations are extrapolated from adult studies and based on expert consensus There is a need for specific definitions for ARDS in children to enable research The PALICC (PALISI consensus onference) recommendations will be a good start
Thank you.