Chapter 7: Acute Respiratory Distress Syndrome - PowerPoint PPT Presentation

Loading...

PPT – Chapter 7: Acute Respiratory Distress Syndrome PowerPoint presentation | free to view - id: 553564-MjNkM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Chapter 7: Acute Respiratory Distress Syndrome

Description:

Chapter 7: Acute Respiratory Distress Syndrome James D. Fortenberry, MD, FCCM, FAAP Medical Director, Critical Care Medicine and Pediatric/Adult ECMO – PowerPoint PPT presentation

Number of Views:765
Avg rating:3.0/5.0
Slides: 82
Provided by: KDur9
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Chapter 7: Acute Respiratory Distress Syndrome


1
Chapter 7 Acute Respiratory Distress Syndrome
  • James D. Fortenberry, MD, FCCM, FAAP
  • Medical Director, Critical Care Medicine and
    Pediatric/Adult ECMO
  • Childrens Healthcare of Atlanta at Egleston

2
ARDS What Is It?
  • Term first introduced in 1967
  • Acute respiratory failure with non-cardiogenic
    pulmonary edema, capillary leak after diverse
    insult
  • Adult RDS defined to differentiate from neonatal
    surfactant deficiency
  • Problems with definition troubled literature
  • Murray score 1988 CXR, PEEP, Hypoxemia,
    Compliance
  • Synonyms
  • Shock lung
  • Da Nang Lung
  • Traumatic wet lung

3
New and Improved
  • Adult Respiratory Distress Syndrome
  • Acute Respiratory Distress Syndrome

4
ARDS New Definition
  • Criteria
  • Acute onset
  • Bilateral CXR infiltrates
  • PA pressure lt 18 mm Hg
  • Classification
  • Acute lung injury - PaO2 F1O2 lt 300
  • Acute respiratory distress syndrome - PaO2 F1O2
    lt 200

- 1994 American - European Consensus
Conference
5
ARDS - Epidemiology
  • New criteria allow better estimate of incidence
  • 1994 criteria in Sweden ALI 17.9/100,000
    13.5/100,000 ARDS
  • US may be closer to 75/1000,000
  • Prospective data pending
  • Incidence in children appears similar
  • 5-9 of PICU admissions

6
Clinical Disorders Associated with ARDS
7
The Problem Lung Injury
Davis et al., J Peds 199312335
Non-infectious Pneumonia 14
Cardiac Arrest 12
Infectious Pneumonia 28
Hemorrhage 5
Trauma 5
Other 4
Septic Syndrome 32
8
ARDS - Pathogenesis
  • Instigation
  • Endothelial injury increased permeability of
    alveolar - capillary barrier
  • Epithelial injury alveolar flood, loss of
    surfactant, barrier vs. infection
  • Pro-inflammatory mechanisms

9
ARDS Pathogenesis Resolution Phase
  • Equally important
  • Alveolar edema - resolved by active sodium
    transport
  • Alveolar type II cells - re-epithelialize
  • Neutrophil clearance needed

10
(No Transcript)
11
ARDS - Pathophysiology
  • Capillary leaknon-cardiogenic pulmonary edema
  • Inflammatory mediators
  • Diminished surfactant activity and airway
    collapse
  • Reduced lung volumes
  • Heterogeneous
  • Baby Lungs
  • Altered pulmonary hemodynamics

12
ARDSCT Scan View
13
ARDS - Pathophysiology Diminished Surfactant
Activity
  • Surfactant production and composition altered in
    ARDS low lecithin-sphingomyelin ratio
  • Components of edema fluid may inactivate
    surfactant

14
ARDS - Pathophysiology Diminished Surfactant
Activity
  • Surfactant product of Type II pneumocytes
  • Importance of surfactant
  • P 2T/r (Laplace equation P trans-pulmonary
    pressure, T surface tension, r radius)
  • Surfactant proportions surface tension to surface
    area thus

15
(No Transcript)
16
(No Transcript)
17
ARDS - Pathophysiology Lung Volumes
  • Reduced lung volumes, primarily reduced FRC
  • FRC ? Nl
  • Low FRC-large intrapulmonary shunt, hypoxemia
  • Implies
  • lower compliance flatter PV curve
  • marked hysteresis
  • PV curve concave above FRC and inflection point
    at volume gt FRC
  • closing volume in range of tidal volume
  • resistance increased primarily due to mechanical
    unevenness (vs. airway R) high flow rates
    helpful

18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
ARDS - Pathophysiology Lung Volumes
  • FRC Volume of gas in lungs at end of normal
    tidal expiration outward recoil of chest wall
    inward recoil of lungs
  • Normal FRC
  • FRC decreased by 20-40 in ARDS
  • FRC decreased by 20-30 when supine elevate
    head!

22
ARDS - Pathophysiology Mediators
  • Massive literature
  • Mediators involved but extent of cause/effect
    unknown
  • Cellular
  • neutrophils-causative depletion in models can
    obliterate lesion ARDS can occur in neutropenic
    patient direct endothelial injury, release
    radicals, proteolytic enzymes
  • macrophages-release cytokines

23
ARDS - Pathophysiology Mediators
  • Humoral
  • Complement
  • Cytokines TNF, IL-1
  • PAF, PGs, leukotrienes
  • NO
  • Coagulant pathways

24
ARDS - PathophysiologyPulmonary Edema
  • Non-cardiogenic pulmonary edema-Starling formula
  • What changes in ARDS?
  • Q K(Pc - Pis) - ? (?pl - ?is)
  • Q
  • K
  • Pc Pis
  • ?
  • ?pl ?is

25
(No Transcript)
26
Phases of ARDS
  • Acute - exudative, inflammatory capillary
    congestion, neutrophil aggregation, capillary
    endothelial swelling, epithelial injury hyaline
    membranes by 72 hours
  • (0 - 3 days)
  • Sub-acute - proliferative proliferation of type
    II pneumocytes (abnormal lamellar bodies with
    decreased surfactant), fibroblasts-intra-alveolar,
    widening of septae
  • (4 - 10 days)
  • Chronic - fibrosing alveolitis remodeling by
    collagenous tissue, arterial thickening,
    obliteration of pre-capillary vessels cystic
    lesions
  • ( gt 10 days)

27
(No Transcript)
28
ARDS - Outcomes
  • Most studies - mortality 40 to 60 similar for
    children/adults
  • Death is usually due to sepsis/MODS rather than
    primary respiratory
  • Mortality may be decreasing
  • 53/68 39/36

29
ARDS - Principles of Therapy
  • Provide adequate gas exchange
  • Avoid secondary injury

30
(No Transcript)
31
Therapies for ARDS
Mechanical Ventilation
Innovations NO PLV Proning Surfactant Anti-Inflam
matory
Gentle ventilation Permissive hypercapnia Low
tidal volume Open-lung HFOV
ARDS
Extrapulmonary Gas Exchange
Total Implantable Artificial Lung
IVOX IV gas exchange
AVCO2R
ECMO
32
The Dangers of Overdistention
  • Repetitive shear stress
  • Injury to normal alveoli
  • inflammatory response
  • air trapping
  • Phasic volume swings volume trauma

33
The Dangers of Atelectasis
  • compliance
  • intrapulmonary shunt
  • FiO2
  • WOB
  • inflammatory response

34
Lung Injury Zones
Overdistention
Sweet Spot
Atelectasis
35
ARDS George H. W. Bush Therapy
  • Kinder, gentler forms of ventilation
  • Low tidal volumes (6-8 vs.10-15 cc/kg)
  • Open lung Higher PEEP, lower PIP
  • Permissive hypercapnia tolerate higher pCO2

36
(No Transcript)
37
Lower Tidal Volumes for ARDS
  • Multi-center trial, 861 adult ARDS
  • Randomized
  • Tidal volume 12 cc/kg
  • Plateau pressure lt 50 cm H2O
  • vs
  • Tidal volume 6 cc/kg
  • Plateau pressure lt 30 cm H2O

ARDS Network, NEJM, 342 2000
38
Lower Tidal Volumes for ARDS
22 decrease


ARDS Network, NEJM, 342 2000
p lt .001
39
Is turning the ARDS patient prone to be helpful?
40
Prone Positioning in ARDS
  • Theory let gravity improve matching perfusion to
    better ventilated areas
  • Improvement immediate
  • Uncertain effect on outcome

41
(No Transcript)
42
Prone Positioning in Adult ARDS
  • Randomized trial
  • Standard therapy vs. standard prone positioning
  • Improved oxygenation
  • No difference in mortality, time on ventilator,
    complications
  • Gattinoni et al., NEJM, 2001

43
Prone Positioning in Pediatric ARDSLonger May
Be Better
  • Compared 6-10 hrs PP vs. 18-24 hrs PP
  • Overall ARDS survival 79 in 40 pts.
  • Relvas et al., Chest 2003

44
Brief vs. Prolonged Prone Positioning in Children


Oxygenation Index (OI)

- Relvas et al., Chest 2003
45
High Frequency OscillationA Whole Lotta Shakin
Goin On
46
Its not absolute pressure, but volume or
pressure swings that promote lung injury or
atelectasis.
- Reese Clark
47
High Frequency Ventilation
  • Rapid rate
  • Low tidal volume
  • Maintain open lung
  • Minimal volume swings

48
High Frequency Oscillatory Ventilation
49
(No Transcript)
50
HFOV is the easiest way to find the
ventilation sweet spot
51
HFOV Benefits Vs. Conventional Ventilation
52
HFOV vs. CMV in Pediatric Respiratory Failure
Results
  • Greater survival without severe lung disease
  • Greater crossover to HFOV and improvement
  • Failure to respond to HFOV strong predictor of
    death

Arnold et al, CCM, 1994
53
HFOV vs. CMV in Pediatric Respiratory Failure

- Arnold et al, CCM, 1994
54
HFOV Outcomes of Randomized Controlled Trials
  • HFOV
  • Reduces need for ECMO, chronic lung disease in
    neonates
  • Improves survival without CLD in pediatric ARDS

55
(No Transcript)
56
Pediatric ECMO
  • Potential candidates
  • Neonate - 18 years
  • Reversible disease process
  • Severe respiratory/cardiac failure
  • lt 10 days mechanical ventilation
  • Acute, life-threatening deterioration

57
(No Transcript)
58
Impact of ECMO on Survival in Pediatric
Respiratory Failure
  • Retrospective, multi-center cohort analysis
  • 331 patients, 32 hospitals
  • Use of ECMO associated with survival (p lt .001)
  • 53 diagnosis and risk-matched pairs
  • ECMO decreased mortality (26 vs 47, p
    lt .01)

-Green et al, CCM, 241996
59
(No Transcript)
60
Pediatric Respiratory ECMO - Childrens
Healthcare of Atlanta
61
Other Cost Intensive Therapies
Therapy Cost/Patient Pediatric ECLS
232, 941 Pediatric Liver Transplant
206, 375 Pediatric Heart Transplant
126,695
62
ECMO Comparison to Other Expensive Therapies
Vats et al., CCM, 1998
63
If you think about ECMO, it is worth a call to
consider ECMO
64
Surfactant in ARDS
  • ARDS
  • surfactant deficiency
  • surfactant present is dysfunctional
  • Surfactant replacement improves physiologic
    function

65
Calfs Lung Surfactant Extract in Acute Pediatric
Respiratory Failure
  • Multi-center trial-uncontrolled, observational
  • Calf lung surfactant (Infasurf) intra-tracheal
  • Immediate improvement and weaning in 24/29
    children with ARDS
  • 14 mortality

-Willson et al,CCM, 241996
66
Surfactant in Pediatric ARDS
  • Current randomized multi-center trial
  • Placebo vs calf lung surfactant (Infasurf)
  • Childrens at Egleston is a participating
    center-study closed, await results

67
Steroids in ARDS
  • Theoretical anti-inflammatory, anti-fibrotic
    benefit
  • Previous studies with acute use (1st 5 days)
  • No benefit
  • Increased 2? infection

68
Effects of Prolonged Steroids in Unresolving ARDS
  • Randomized, double-blind, placebo-controlled
    trial
  • Adult ARDS ventilated for gt 7 days without
    improvement
  • Randomized
  • Placebo
  • Methylprednisolone 2 mg/kg/day x 4 days, tapered
    over 1 month

Meduri et al, JAMA 280159, 1998
69
Steroids in Unresolving ARDS
  • By day 10, steroids improved
  • PaO2/FiO2 ratios
  • Lung injury/MOD scores
  • Static lung compliance
  • 24 patients enrolled study stopped due to
    survival difference

Meduri et al, JAMA, 1998
70
Steroids in Unresolving ARDS



plt.01
- Meduri et al., JAMA, 1998
71
Inhaled Nitric Oxide in Respiratory Failure
  • Neonates
  • Beneficial in term neonates with PPHN
  • Decreased need for ECMO
  • Adults/Pediatrics
  • Benefits - lowers PA pressures, improves gas
    exchange
  • Randomized trials No difference in mortality or
    days of ventilation

72
ECMO and NO in Neonates
  • ECMO improves survival in neonates with PPHN (UK
    study)
  • NO decreases need for ECMO in neonates with PPHN
    64 vs 38 (Clark et
    al, NEJM, 2000)

73
Effects of Inhaled Nitric Oxide In Children with
AHRF
  • Randomized, controlled, blinded multi-center
    trial
  • 108 children with OI gt 15
  • Randomized Inhaled NO 10 ppm vs. mechanical
    ventilation alone

Dobyns, Cornfield, Anas, Fortenberry et al., J.
Peds, 1999
74
(No Transcript)
75
Inhaled NO and HFOV In Pediatric ARDS

Dobyns et al., J Peds, 2000
76
Partial Liquid Ventilation
77
Partial Liquid Ventilation
  • Mechanisms of action
  • oxygen reservoir
  • recruitment of lung volume
  • alveolar lavage
  • redistribution of blood flow
  • anti-inflammatory

78
Liquid Ventilation
  • Pediatric trials started in 1996
  • Partial FRC (15 - 20 cc/kg)
  • Study halted 1999 due to lack of benefit
  • Adult study (2001) no effect on outcome

79
ARDS- Mechanical Therapies
  • Prone positioning - Unproven outcome
    benefit
  • Low tidal volumes - Outcome benefit in
    large study
  • Open-lung strategy - Outcome benefit in
    small study
  • HFOV -Outcome benefit in small study
  • ECMO - Proven in neonates unproven in
    children

80
Pharmacologic Approaches to ARDS Randomized
Trials
Glucocorticoids - acute - no benefit -
fibrosing alveolitis - lowered mortality,
small study Surfactant - possible benefit in
children Inhaled NO - no
benefit Partial liquid ventilation - no benefit
81
We must discard the old approach and continue
to search for ways to improve mechanical
ventilation. In the meantime, there is no
substitute for the clinician standing by the
ventilator
- Martin J. Tobin, MD
About PowerShow.com