ventilatory management pf acute lung injury & acute respiratory distress syndrome by sherif g....

Ventilatory management pf Ventilatory management pf acute lung injury & acute acute lung injury & acute

respiratory distress syndromerespiratory distress syndrome

By Sherif G. Anis M.DBy Sherif G. Anis M.D..

• Acute onset of hypoxemiaAcute onset of hypoxemia

• Bilateral Lung infiltrates Bilateral Lung infiltrates

• Absence of left atrial hypertension Absence of left atrial hypertension

• Risk factors: Risk factors:

Pulmonary e.g. PneumoniaPulmonary e.g. Pneumonia

Non pulmonary e.g. Pancreatitis Non pulmonary e.g. Pancreatitis

Acute respiratory distress syndrome

Ventilatory management of ALI & ARDS

SourcSourcee

OxygenationOxygenation Chest Chest RadiographRadiograph

Other CriteriaOther Criteria

Petty Petty and and

AshbauAshbau,,

1971 1971

Cyanosis Cyanosis refractoryrefractory

to oxygen to oxygen therapy therapy

Diffuse alveolarDiffuse alveolar

infiltrates on infiltrates on frontalfrontal

chest radiographchest radiograph

Impaired pulmonaryImpaired pulmonary

compliancecompliance

Marked difference in Marked difference in inspired vs. arterial inspired vs. arterial oxygen tensionsoxygen tensions

Murray Murray et al,et al,

19881988

Hypoxemia Hypoxemia (PaO2(PaO2/FIO/FIO2),2),

by quintiles by quintiles

No. of quadrantsNo. of quadrants

of alveolarof alveolar

consolidationconsolidation

on frontal cheston frontal chest

radiograph radiograph

PEEP and respiratoryPEEP and respiratory

system compliancesystem compliance

(by quintiles)(by quintiles)

Preexisting direct orPreexisting direct or

indirect lung injury indirect lung injury Nonpulmonary organ Nonpulmonary organ dysfunction dysfunction

Diagnostic Criteria for ARDS


SourcSourcee

OxygenationOxygenationChest Chest RadiographRadiograph

Other CriteriaOther Criteria

Bernard Bernard et al,et al,

19941994

ALI:ALI:

PaO2PaO2/FIO/FIO2 <300,2 <300,

regardless of regardless of PEEP levelPEEP level

ARDS,ARDS, PaO PaO22/FIO/FIO2 2 <200,<200,

regardless of regardless of PEEP level PEEP level

Bilateral Bilateral infiltrates oninfiltrates on

frontal chestfrontal chest

radiography radiography

PCWP <PCWP <18 mm Hg18 mm Hg

if measured orif measured or

no clinical evidenceno clinical evidence

of left atrial of left atrial hypertension hypertension


Diagnostic Criteria for ARDS

•Acute lung injury (ALI)Acute lung injury (ALI)

[PaO2/FIO2] ratio<300) [PaO2/FIO2] ratio<300)

•Acute Respiratory distress Acute Respiratory distress syndrome syndrome

(ARDS):(ARDS):

(PaO2/FIO2 ratio <200) (PaO2/FIO2 ratio <200)


American European consensus conference (AECC) 1994

Mechanical Ventilation in ARDSMechanical Ventilation in ARDS

Injurious ventilator associated lung injury

Necessary to reverse Hypoxaemia


• The lung with ALI or ARDS are The lung with ALI or ARDS are particularly prone to ventilator particularly prone to ventilator associated lung injury: (Baby associated lung injury: (Baby lung)lung)

Collapsed, consolidated, less Collapsed, consolidated, less compliant areas (Dependant)compliant areas (Dependant)

Normal areas (non dependant)Normal areas (non dependant)


• Ventilator associated lung injury:Ventilator associated lung injury:High inflation pressure BarotraumaHigh inflation pressure BarotraumaOver distension VolutraumaOver distension VolutraumaRepetitive opening & closing of alveoliRepetitive opening & closing of alveoli

Atelect-traumaAtelect-traumaSIRS & cytokines release Biotrauma.SIRS & cytokines release Biotrauma.


• Lung protective ventilation in Lung protective ventilation in comparison with conventional comparison with conventional

approachesapproaches

Evidence SynthesisEvidence Synthesis


Study Study ParticipantsParticipants

ARDSARDS

Network,Network,

20002000

Amato et alAmato et al, , 19981998

Brochard et Brochard et alal, 1998, 1998

Stewart et Stewart et alal, 1998, 1998

Brower et alBrower et al, , 19991999

NoNo.. 86186153531161161201205252

Mean age, yMean age, y 52523535575759594949

Target Target intervention intervention Tidal volume, Tidal volume, mL/kgmL/kg

6 vs. 12 PBW6 vs. 12 PBW ≤≤6 vs. 12 ABW6 vs. 12 ABW 6-10 vs. 10-15 6-10 vs. 10-15 DBWDBW

≤≤8 vs. 10-15 8 vs. 10-15 IBWIBW

≤≤8 vs. 10-12 8 vs. 10-12 PBWPBW

Plateau Plateau pressure, cmpressure, cm H2oH2o

≤≤30 30 vs.vs.≤ 50≤ 50 <20 <20 vs. vs. unlimited unlimited

25-30 25-30 vs.vs.≤ 60≤ 60 ≤≤30 30 vs.vs. ≤50 ≤50 ≤≤30 30 vs.vs. ≤45-55 ≤45-55

Actual Actual interventionintervention Tidal volume, Tidal volume, mlml_/_/kgkg

6.2 6.2 vs. 11.8 vs. 11.8 384 vs.384 vs.

768 ‡768 ‡ 7.1 7.1 vs. 10.3 vs. 10.3 7.0 7.0 vs. 10.7 vs. 10.7 7.3 7.3 vs. 10.2 vs. 10.2

Plateau Plateau pressure, cmpressure, cm H2oH2o

25 25 vs. 33 vs. 33 30 30 vs. 37 vs. 37 26 26 vs. 32 vs. 32 22 22 vs. 27 vs. 27 25 25 vs. 31 vs. 31

Outcomes Outcomes mortalitymortality, %, %

31 31 vs. 40vs. 40§§ 38 38 vs. 71vs. 71. . 47 47 vs. 38 vs. 38 50 50 vs. 47 vs. 47 50 50 vs. 46 vs. 46

PP valuevalue 0.0070.0070.0010.0010.380.380.720.720.610.61

• 3 Meta analysis of these 5 clinical 3 Meta analysis of these 5 clinical trials have been performed:trials have been performed:

One analysis shows that there is no reflection One analysis shows that there is no reflection of the standard of care, in addition low tidal of the standard of care, in addition low tidal volumes may be harmful, in the intervention volumes may be harmful, in the intervention group of the 2 trials showing survival group of the 2 trials showing survival advantage. (Eichacker PQ et al, 2002)advantage. (Eichacker PQ et al, 2002)

2 subsequent meta analyses suggested that 2 subsequent meta analyses suggested that volume limited ventilation, particularly in the volume limited ventilation, particularly in the setting if elevated plateau pressure > 30 setting if elevated plateau pressure > 30 cmH2O, has a short term survival benefit. cmH2O, has a short term survival benefit. (Petruccin et al, 2004) (Moran Jl et al, 2005) (Petruccin et al, 2004) (Moran Jl et al, 2005)


One meta analysis also concluded that One meta analysis also concluded that decreased tidal volume may be decreased tidal volume may be advantageous below a threshold level advantageous below a threshold level (<7.7 ml/Kg BW) (Moran Jl et al, 2005)(<7.7 ml/Kg BW) (Moran Jl et al, 2005)


Pressure & volume limitationPressure & volume limitation Higher PEEPHigher PEEP Recruitment maneuvers (Dynamic Recruitment maneuvers (Dynamic

process of reopening collapsed alveoli process of reopening collapsed alveoli through increase in trans pulmonary through increase in trans pulmonary pressure)pressure)

Lung protective ventilation strategy


Which method of recruitment maneuvers Which method of recruitment maneuvers should be Used ?should be Used ?

1.1. The most well Known method of recruitment The most well Known method of recruitment maneuver is sustained application of CPAP of 30- maneuver is sustained application of CPAP of 30- 50 Cm H2O for 30 seconds50 Cm H2O for 30 seconds

2.2. Periodic recruitment with a series of traditional Periodic recruitment with a series of traditional sigh breathssigh breaths

3.3. Intermittently raising PEEP over several breathsIntermittently raising PEEP over several breaths

4.4. Extended sigh maneuver with step wise increase in Extended sigh maneuver with step wise increase in PEEP while Vt is decreasedPEEP while Vt is decreased

5.5. Intermittent application of pressure controlled Intermittent application of pressure controlled ventilation with incremental high PEEPventilation with incremental high PEEP

Lung protective ventilationn etiology


Permissive hypercapnea (acute respiratory Permissive hypercapnea (acute respiratory acidosis)acidosis)

TTT: increase respiratory rate in a stepwise up to TTT: increase respiratory rate in a stepwise up to 3535

Bicarbonate infusionBicarbonate infusion increase Vtincrease Vt Worsened oxygenation & transient desaturationWorsened oxygenation & transient desaturation Increased sedation or analgesiaIncreased sedation or analgesia Hypotension & arrhythmiasHypotension & arrhythmias Barotraumas (Pneumothorax)Barotraumas (Pneumothorax) Bacterial translocationBacterial translocation

Consequences of lung protective ventilation


• Further studies are needed to:Further studies are needed to: Inform on a clinically relevant threshold if Inform on a clinically relevant threshold if

hypercapnea,hypercapnea,

& acidosis both require intervention& acidosis both require intervention Increased sedation & analgesic effects (Kahn JM & Increased sedation & analgesic effects (Kahn JM &

colleagues, 2005 show no increase in sedation colleagues, 2005 show no increase in sedation use in low tidal volume ventilation)use in low tidal volume ventilation)

Safety of recruitment maneuversSafety of recruitment maneuvers


• High-frequency ventilation (jet, High-frequency ventilation (jet, oscillation, and percussive oscillation, and percussive ventilation)ventilation)

HFOV allows for higher mean airway HFOV allows for higher mean airway pressures & markedly reduced tidal pressures & markedly reduced tidal volumes (1-3 ml/kg) Lung volumes (1-3 ml/kg) Lung recruitment & reduce lung injury. recruitment & reduce lung injury.

Alternative Ventilatory Approaches to Lung Protection


• Airway pressure release ventilation Airway pressure release ventilation (APRV)(APRV)

It provides two levels of airway pressure It provides two levels of airway pressure (P (P highhigh & P & P lowlow) during two time periods (T ) during two time periods (T highhigh & T & T lowlow) , usually a long T) , usually a long Thighhigh & short & short TTlowlow with spontaneous breathing during with spontaneous breathing during both.both.

Advantages: Decrease barotrauma, Advantages: Decrease barotrauma, provide better V/P matching, cardiac provide better V/P matching, cardiac filling & patient comfort.filling & patient comfort.


Alternative Ventilatory Approaches to Lung Protection

Prone positioning:Prone positioning: recruitment of dorsal (nondependent) recruitment of dorsal (nondependent)

atelectatic lung units, improved atelectatic lung units, improved respiratory mechanics, decreased respiratory mechanics, decreased ventilation- perfusion mismatch, increased ventilation- perfusion mismatch, increased secretion drainage, reduced and improved secretion drainage, reduced and improved distribution of injurious mechanical forces distribution of injurious mechanical forces

(Pelozi P et al, 2002)(Pelozi P et al, 2002)

Adjunctive therapies to lung-protective Ventilation


inhaled nitric oxide :inhaled nitric oxide :

Selective VD in ventilated lung units Selective VD in ventilated lung units improving V/Q mismatch, decrease improving V/Q mismatch, decrease PaO2 & pulmonary hypertension ( no PaO2 & pulmonary hypertension ( no sustained clinical benefit) (Tayler RW sustained clinical benefit) (Tayler RW et al, 2004)et al, 2004)

Adjunctive therapies to lung-protective Ventilation


• Irrespective of this controversy as to Irrespective of this controversy as to whether the exact ARDSNet protocol should whether the exact ARDSNet protocol should be adopted, the existing evidence supports be adopted, the existing evidence supports that clinicians should change their practice that clinicians should change their practice and adopt volume and pressure limited and adopt volume and pressure limited ventilation for patients with ALI or ARDS. As ventilation for patients with ALI or ARDS. As additional evidence emerges, ongoing additional evidence emerges, ongoing reassessment and evolution of these reassessment and evolution of these protocols will be necessary. protocols will be necessary.


1.1. mechanical ventilation, although life saving, can mechanical ventilation, although life saving, can contribute to patient morbidity and contribute to patient morbidity and mortalitymortality

2.2. Volume and pressure limited ventilation clearly Volume and pressure limited ventilation clearly leads to improved patient survivalleads to improved patient survival

3.3. The role of reThe role of re cruitment maneuvers, higher levels of cruitment maneuvers, higher levels of PEEP, or both remain controversial PEEP, or both remain controversial

4.4. At this time, use of alternative modes of ventilation At this time, use of alternative modes of ventilation (e.g., HFOV) and adjunctive therapies (e.g., inhaled (e.g., HFOV) and adjunctive therapies (e.g., inhaled nitric oxide and prone positioning) should be limited nitric oxide and prone positioning) should be limited to future clinical trials and rescue therapy for to future clinical trials and rescue therapy for patients with ALI or ARDS with life threatening patients with ALI or ARDS with life threatening hypoxemia failing maximal conventional lung hypoxemia failing maximal conventional lung protective ventilation.protective ventilation.

Conclusions and Future Considerations


Thank youThank you

ventilatory management pf acute lung injury & acute respiratory distress syndrome by sherif g....

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