ALI/ARDS Zsolt Molnár University of Szeged AITI. Introduction ARDS is not a definitive illness Mortality: 26% -74% Furtos-Vivar F et al. Curr Opin Crit.

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