Ventilation Strategies Ventilation Strategies in ARDS in ARDS

MICU-ER Joint MICU-ER Joint ConferenceConference

Dr. Rachmale, Dr. Dr. Rachmale, Dr. Prasankumar 12/3/08Prasankumar 12/3/08

Initial ICU Initial ICU ManagementManagement

EGDT implemented, CVP- Subclavian line EGDT implemented, CVP- Subclavian line placed, Initial CVP=placed, Initial CVP=88, Lactic Acid- 5.5 , Lactic Acid- 5.5

CVP aim > 12, Map > 65CVP aim > 12, Map > 65 IV fluids 3L, Urine IV fluids 3L, Urine output >0.5ml/kg/hroutput >0.5ml/kg/hr

Antibiotics- zosyn/ ciprofloxacin within one hourAntibiotics- zosyn/ ciprofloxacin within one hour

Initial ABG:Initial ABG: pH: 7.19 Po2: 60 Pco2: 48, sat 84% pH: 7.19 Po2: 60 Pco2: 48, sat 84% At this time Ventilator setting:At this time Ventilator setting: AC/TV-400/RR-28/FiO2 100%/PAP-36/PLP-30/ AC/TV-400/RR-28/FiO2 100%/PAP-36/PLP-30/

peep- 7peep- 7 Pao2/Fi02:60Pao2/Fi02:60

ARDS- DefinitionARDS- Definition

1. PaO2/FiO2 ≤ 200 1. PaO2/FiO2 ≤ 200

2. Bilateral (patchy, diffuse, or 2. Bilateral (patchy, diffuse, or homogeneous) infiltrates homogeneous) infiltrates consistent with pulmonary consistent with pulmonary edemaedema

3. No clinical evidence of left 3. No clinical evidence of left atrial hypertension ( PCWP<18)atrial hypertension ( PCWP<18)

NIH-NHLBI ARDS Network NIH-NHLBI ARDS Network Cause of Lung InjuryCause of Lung Injury

NHLBI ARDS Clinical Trials Network. N Engl J Med. 2004.

Transfusion5%

Trauma8%

Other10%

Aspiration15%

Pneumonia40%

Sepsis22%

Mortality from ARDSMortality from ARDS

ARDS mortality rates - 31% to 74%The main causes of death are non-respiratory causes (i.e., die with, rather than of, ARDS).

Early deaths (within 72 hours) are caused by the underlying illness or injury, whereas late deaths are caused by sepsis or multi-organ dysfunction

Stages of ARDSStages of ARDS

RATIONALE FOR LOW STRETCH VENTILATION

Lung injury from:

• Over-distension/shear - > physical injury

• Mechanotransduction - > “biotrauma”

• Repetitive opening/ closing • Shear at open/ collapsed

lung interface

“atelectrauma”

“volutrauma”

ARDSNET- Initial ARDSNET- Initial Ventilator StrategiesVentilator StrategiesLow Tidal Volume (6ml/kg) Calculate predicted body weight (PBW) Calculate predicted body weight (PBW)

Males = 50 + 2.3 [height (inches) –

Females = 45.5 + 2.3 [height (inches) -60]

Plateau Pressure < 30 cms

Minimizing VILI- Minimizing VILI- Plateau pressure goalsPlateau pressure goals

If Pplat > 30 cm H2OIf Pplat > 30 cm H2O: : decrease VT by decrease VT by 1ml/kg steps (minimum = 4 ml/kg)1ml/kg steps (minimum = 4 ml/kg)

If Pplat < 25 cm H2O and VT< 6 ml/kgIf Pplat < 25 cm H2O and VT< 6 ml/kg, , increase VT by 1 ml/kg until Pplat > 25 cm increase VT by 1 ml/kg until Pplat > 25 cm H2O or VT = 6 ml/kgH2O or VT = 6 ml/kg

Mortality: low vs. Mortality: low vs. traditional tidal traditional tidal volumevolume

31

39.8

0

10

20

30

40

50

Mo

rtal

ity

(%)

Low tidalvolume

Traditionaltidal

volume

RRR=22 %ARR=8.8 %NNT=12

p=0.007

ARDSNet. NEJM 2000;342:1301.

PEEP in ARDSPEEP in ARDS Protective effect by avoiding alveolar collapse Protective effect by avoiding alveolar collapse

and reopeningand reopening Prevent surfactant loss in the airways avoid

surface film collapse Use of PEEP avoids end-expiratory collapse,

thus Recruitment is obtained at end-inspiration

Lower PEEP/Higher FiO2

FiO2FiO2 .3 .3 0.0.4 4

0.0.4 4

0.5 0.5 0.5 0.5 0.6 0.6 0.7 0.7 0.7 0.7 0.70.7 0.80.8 0.90.9 0.90.9 0.90.9 1.1.00

PEEPEEP P

5 5 5 5 8 8 8 8 10 10 10 10 10 10 12 12 1414 1414 1414 1616 1818 1818--2424

Recruitment Maneuvers

Improve hypoxia Recruitment of nonaerated lung units (collapsed alveoli)-

caudal and dependent lung regions in patients lying supine

Maneuvers – short-lasting increases in intrathoracic pressures• Intermittent increase of PEEP

• On AC mode or through ambu bag with PEEP valve• Continuous positive airway pressure (CPAP)

• Cahnge back up rate and apnea alarm• Increasing the ventilatory pressures ~ 50 cm H2O for

1-2 minutes • Intermittent sighs or Extended sighs

Can cause Hypotension, pneumothorax, Needs Experience

Management of Our Management of Our patientpatient Initial ABG:Initial ABG:

pH: 7.19 Po2: 60 Pco2: 48, sat 84% pH: 7.19 Po2: 60 Pco2: 48, sat 84% At this time Ventilator setting:At this time Ventilator setting:

AC/ TV-400/ RR-28 /FiO2 100%/PAP-36/PLP-30/ AC/ TV-400/ RR-28 /FiO2 100%/PAP-36/PLP-30/

peep – 10 sat 84%peep – 10 sat 84% Initial changes made:Initial changes made:

AC/ TV-400/ AC/ TV-400/ RR-35 RR-35 /FiO2 100%/PAP-36/PLP-30/ /FiO2 100%/PAP-36/PLP-30/ peep- 17 sat 94%peep- 17 sat 94%

Recruitment NeededRecruitment Needed

Management Management continuedcontinued

After transfer to MICU, episodes of After transfer to MICU, episodes of hypoxia despite maximal mechanical hypoxia despite maximal mechanical ventilationventilation

Improved with recruitment maneuversImproved with recruitment maneuvers Next 48 hours : Vt decreased to Next 48 hours : Vt decreased to 370370

then 320, PEEP increased to then 320, PEEP increased to 2020 then then 2222, plateau pressures , plateau pressures 34-37 34-37 on 100% on 100% FiO2FiO2

Even such Low Vt, unable to maintain Even such Low Vt, unable to maintain plateau pressures below 30 plateau pressures below 30

Permissive HypercapniaPermissive Hypercapnia

Management Management continuedcontinued

Severe sepsisSevere sepsis septic shock, apache septic shock, apache 3838

Aggressive hydration, Vasopressor Aggressive hydration, Vasopressor (Levophed) to maintain MAP>65, fixed (Levophed) to maintain MAP>65, fixed dose vasopressin, hydrocortisone and dose vasopressin, hydrocortisone and xigris ( Activated Protein C) givenxigris ( Activated Protein C) given

Lactate remained high, SvO2: 70-77% Lactate remained high, SvO2: 70-77% BC – Strep pneumonia-BC – Strep pneumonia-

Hospital CourseHospital Course

During entire 25 day course Fio2 During entire 25 day course Fio2 requirements could not be lowered requirements could not be lowered to less than 80%, the least PEEP to less than 80%, the least PEEP was 14was 14

Peak and plateau pressure Peak and plateau pressure remained highremained high

Septic shockSeptic shock MSOF MSOF death death

Alternative strategiesAlternative strategies Prone Positioning-Prone Positioning- recruitment of recruitment of

posterior lung fieldsposterior lung fields High frequency oscillatory ventilation High frequency oscillatory ventilation

(HFOV)-(HFOV)- low tial volumes at high low tial volumes at high frequencesfrequences

Nitric oxide-Nitric oxide- selective vasodilator of selective vasodilator of vessels that perfuse well ventilated lung vessels that perfuse well ventilated lung zoneszones

Extracorporeal membrane oxygenation Extracorporeal membrane oxygenation (ECMO(ECMO)-Veno-arterial bypass which )-Veno-arterial bypass which supports gas exchange and oxygenationsupports gas exchange and oxygenation

Limited VT 6 mL/kg PBW to avoid alveolar distension

End-inspiratory plateau pressure < 30 cm H2O

Adequate end expiratory lung volumes utilizing PEEP and higher mean airway pressures to minimize atelectrauma and improve oxygenation

Consider recruitment maneuvers

Summary of Summary of RecommendationsRecommendations