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ALI/ARDS
Zsolt MolnárUniversity of Szeged
AITI
Introduction
• ARDS is not a definitive illness• Mortality: 26% -74%
Furtos-Vivar F et al. Curr Opin Crit Care 2004; 10: 1-6
• Definition: Acute Lung Injury (ALI), ARDS• Ashbaugh-1967, Murray-1988, American-European
Consensus Conference on ARDS-1994, etc.
Pathophysiology
• Disorders associated with ARDS• Primary:
– Aspiration, inhalation
– Pneumonia
• Secondary:– Shock
– Infection
– Trauma
– Pancreatitis
• Classification• Type I – hypoxic
• Type II – hypercapnic
• Mixed
• Participating factors• Initial insult
• Inflammatory cascade
• Endothelium demage
• „Non-cardiogenic” pulmonary oedema
• Fibrosis
Acute respiratory failure
Diagnosis of severity
• CXR• Atelectasis/quadrant: 0-4
• PaO2/FiO2• <100 - 300<: 0-4
• PEEP (cmH2O)
5 - 15 0-4pont
• Compliance (ml/cmH2O)
29 - 80 0-4pont
2,5 = ARDS1,5-2,5=ALI
Murray JF et al. Am Rev Respir Dis 1988; 138: 720-723
Diagnostic signs
• Clinical• Acute onset
• Tachypnea (>30)
• Laboured breathing
• Physiologic• Hypoxia (PaO2/FiO2<250Hgmm)
• X-ray• Bilateral infiltrates
Physiology, pathophysiology
Alveolar oxygenation
Molnár ‘99
PAO2
PaO2=120 Hgmm
120Hgmm
PAO2=FiO2 x [(PB-PH2O) – PaCO2/R]
PA-aO2 20Hgmm
PvO2=40 Hgmm
Atelectasis and shunt
Molnár ‘99
PvO2=40 Hgmm
PaO2 = (120+40)/2 = 80 Hgmm
120Hgmm
O2
• In normal lungs:– CC in ERV– FRC>CC
• ALI/ARDS:– CC within VT
– FRC<CC
VT
FRCERV
RVCC CC
Closing capacity (CC)
• „Iso-shunt” diagramNunn JF. Appl. Resp Physiol., 1993
The degree of shunt
Molnár ‘99
100
200
300
400
PaO
2 Hgm
m
0 5% 10%
15%
20%
25%
30%
50%
FiO2
0,2 0,6 1,0
• Inflammed organs need rest
• IPPV: life saving interventionWareLB, Matthay MA. N Engl J Med 2000; 342: 1334-49
• IPPV: if applied incorrectly: „can be deadly”
Tobin MJ. N Engl J Med 2001; 344: 1986-96
Therapeutic dilemma
Atelectasy and radiology
Gattinoni L, et al. Intensive Care Med 1986; 12: 137-142
Gary F. Nieman SUNY USA
Normal lung ARDS lung
DiRocco J, et al. Intensive Care Med 2007; 33: 1204-11
Correlation between alveolar recruitment/derecruitment and inflection point on the pressure-volume curve
Alveolar recruitment
„Open up the lung and keep it open!”Lachmann B. ICM 1992; 18: 319-321
LIP
UIP
Pelosi P, et al. AJRCCM 2001; 164: 122Gattinoni L, et al AJRCCM 2001; 164 1701
Atelectasy Overdistension
Increasing PEEP
Ideal PEEP: moving tartget
Ideal PEEP
Physiology - revisited
• Breathing• 15/min
• VT: 4-7 ml/kg
• Ppleur: ±2-3 cmH2O
• FiO2= 0.21
• Result• PaO2: 100 mmHg
• PaCO2: 40 mmHg
Why?
Because it’s good for us!
• 40 year old woman• Committed sucide (20 tbl chlorpromazine)• Ambulance – Psychiatry
• Gastric lavage• A few hours later: acute abdominal pain
• Surgery• Gastric perforation: emergency surgery
• ICU
Case history
• In a few days
• Secondary ARDS = LIS>2.5– FiO2: 0.8
– PaO2: 65 Hgmm
– PEEP: 15 H2Ocm
Case history
Hemodynamic and respiratory changes during lung recruitment and descending optimal PEEP titration in patients with ARDS
Tóth I, et al. Crit Care Med 2007; 35: 787-793
• Lung recruitment• Anaesthesia + muscle relaxation
• PCV, I:E=1:1, RR: 20/min
• FiO2: 1.0
• PEEP: 26 H2OcmP: 40 H2Ocm/40 sec
Methods
Paninspiratory, „tidal recruitment”
Pelosi P, et al. AJRCCM 2001; 164: 122
Paninspiratory, „tidal recruitment”
Pelosi P, et al. AJRCCM 2001; 164: 122
• Optimal PEEP titration• „Closing pressure”
• Ideal PEEP: when PaO2 > 10%
• VT=4ml/kg
• PEEP: 26-24-22…/4 min
Methods
• Optimal PEEP titration• PEEP0: 15 H2Ocm - PaO2: 276
• PEEP: 26 H2Ocm - PaO2: 436 Hgmm
• ….
• PEEP: 18 H2Ocm - PaO2: 445 Hgmm
• PEEP: 16 H2Ocm - PaO2: 375 Hgmm• Optimális PEEP: 18 vízcm
Optimal PEEP
• After PEEP titration– Opening: („40/40”) at PEEP of 18– Result:
• FiO2: 0.5 vs 0.8
• VT(6ml/kg): 350 vs 675 ml
P: 14 vs 20 H2Ocm
• PEEP: 18 vs 15 H2Ocm
• PaO2: 115 vs 62 Hgmm
• 40 days ICU – Surgery – Home
Outcome
Tidal volume: VT
small VT
large VT
Volu-, or baro-trauma
small VT
large VT
Volu-, or baro-trauma
VT and inflammatory response
• Inflammatory response: „small” VT vs „large” VT
• Reduced cytokine levels in BAL after 36 hRanieri VM et al, JAMA 1999; 282:54
• Reduced plasma IL-6 on 3rd day on vent.ARDS Network, N Engl J Med 2000; 342: 1301
VT and mortality
• No difference • Brochard et al: n=116, VT:10-15 vs 6-10 ml/kg
Am J Respir Crit Care Med 1998; 158: 1831
• Stewart et al: n=120, VT:10-15 vs 8 ml/kg N Engl J Med 1998; 338: 355
• Difference • Amato: n=53, VT:12 vs 6 ml/kg, M 28. nap: 71 vs 38%
N Engl J Med 1998; 338:347
• Network: n=861, VT:12 vs 6 ml/kg, M: 40% vs 31%ARDS Network, N Engl J Med 2000; 342: 1301
• Network: n=549, 6 ml/kg, M: ~25%ARDS Network, N Engl J Med 2004; 351: 327
Other therapeutic consideration
• Supportive therapy
• Invasive haemodinamic monitoring
• Antibiotics
• Alternative therapies:• Prone positioning
• ECMO
• Nitric oxide (NO)
• Haemofiltration
Summary
• ARDS is not a defintive diagnosis
• IPPV is against physiology
• Protect the lung
• Keep physiolology in mind
There is no substitute for the clinician`s
standing by the ventilator, making necessary
adjustments and monitoring the effects of such
adjustments.
Tobin MJ, N Engl J Med 2000; 342:1360-1
Motto