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 edemaconsistent with pulmonary edema
3. No clinical evidence of left atrial 3. No clinical evidence of left atrial hypertension ( PCWP<18)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
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 Strategies Low 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
Mor
talit
y (%
)
Low tidalvolume
Traditionaltidal
volume
RRR=22 %ARR=8.8 %NNT=12p=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% FiO2on 100% FiO2
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