ALI/ARDSZsolt MolnárUniversity of SzegedAITI
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-EuropeanConsensus 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 - 800-4pont
2,5 = ARDS
1,5-2,5=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
120
Hgmm
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
120
Hgmm
O2
•In normal lungs:
–CC in ERV
–FRC>CC
•ALI/ARDS:
–CC within VT
–FRC<CC
VT
FRC
ERV
RV
CC
CC
Closing capacity (CC)
•„Iso-shunt” diagram
Nunn JF. Appl. Resp Physiol., 1993
The degree of shunt
Molnár ‘99
100
200
300
400
PaO2 Hgmm
0
5%
10%
15%
20%
25%
30%
50%
FiO2
0,2
0,6
1,0
•Inflammed organs need rest
•IPPV: life saving intervention
WareLB, Matthay MA. N Engl J Med 2000; 342: 1334-49
•IPPV: if applied incorrectly: „can bedeadly”
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. NiemanSUNY 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: 122
Gattinoni 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 H2Ocm
•P: 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 h
Ranieri 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