Transcript Document

Ventilation Strategies in
ARDS
MICU-ER Joint Conference
Dr. Rachmale, Dr. Prasankumar
12/3/08
Initial ICU Management
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EGDT implemented, CVP- Subclavian line
placed, Initial CVP=8, Lactic Acid- 5.5
CVP aim > 12, Map > 65 IV fluids 3L,
Urine output >0.5ml/kg/hr
Antibiotics- zosyn/ ciprofloxacin within one
hour
Initial ABG:
pH: 7.19 Po2: 60 Pco2: 48, sat 84%
At this time Ventilator setting:
AC/TV-400/RR-28/FiO2 100%/PAP-36/PLP30/ peep- 7
Pao2/Fi02:60
ARDS- Definition
1. PaO2/FiO2 ≤ 200
2. Bilateral (patchy, diffuse, or
homogeneous) infiltrates
consistent with pulmonary edema
3. No clinical evidence of left atrial
hypertension ( PCWP<18)
NIH-NHLBI ARDS Network
Cause of Lung Injury
Sepsis
22%
Trauma
8%
Aspiration
15%
Pneumonia
40%
Other
10%
NHLBI ARDS Clinical Trials Network. N Engl J Med. 2004.
Transfusion
5%
Mortality from ARDS
ARDS mortality rates - 31% to 74%
The main causes of death are nonrespiratory 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 multiorgan dysfunction
Stages 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
“volutrauma”
“atelectrauma”
ARDSNET- Initial
Ventilator Strategies
 Low
Tidal Volume (6ml/kg)
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- Plateau
pressure goals
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If Pplat > 30 cm H2O: decrease VT by
1ml/kg steps (minimum = 4 ml/kg)
If Pplat < 25 cm H2O and VT< 6
ml/kg, increase VT by 1 ml/kg until Pplat >
25 cm H2O or VT = 6 ml/kg
Mortality: low vs.
traditional tidal volume
50
39.8
Mortality (%)
40
31
p=0.007
30
20
RRR=22 %
ARR=8.8 %
NNT=12
Low tidal
volume
10
0
ARDSNet. NEJM 2000;342:1301.
Traditional
tidal
volume
PEEP in ARDS
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Protective effect by avoiding alveolar collapse and
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
FiO2
.3 0.4 0.4 0.5
PEEP 5
5
8
8
0.5
0.6
0.7
0.7
0.7
0.8
0.9
0.9
0.9
1.0
10
10
10
12
14
14
14
16
18
1824
Recruitment Maneuvers
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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
patient
Initial ABG:
pH: 7.19 Po2: 60 Pco2: 48, sat 84%
 At this time Ventilator setting:
AC/ TV-400/ RR-28 /FiO2 100%/PAP-36/PLP-30/
peep – 10
sat 84%
 Initial changes made:
AC/ TV-400/ RR-35 /FiO2 100%/PAP-36/PLP-30/
peep- 17
sat 94%
 Recruitment Needed
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Management continued
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After transfer to MICU, episodes of
hypoxia despite maximal mechanical
ventilation
Improved with recruitment maneuvers
Next 48 hours : Vt decreased to 370
then 320, PEEP increased to 20 then
22, plateau pressures 34-37 on 100%
FiO2
Even such Low Vt, unable to maintain
plateau pressures below 30
Permissive Hypercapnia
Management continued
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Severe sepsis septic shock, apache
38
Aggressive hydration, Vasopressor
(Levophed) to maintain MAP>65, fixed
dose vasopressin, hydrocortisone and
xigris ( Activated Protein C) given
Lactate remained high, SvO2: 70-77%
BC – Strep pneumonia-
Hospital Course
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During entire 25 day course Fio2
requirements could not be lowered to
less than 80%, the least PEEP was 14
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Peak and plateau pressure remained high
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Septic shock MSOF death
Alternative strategies
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Prone Positioning- recruitment of posterior
lung fields
High frequency oscillatory ventilation
(HFOV)- low tial volumes at high frequences
Nitric oxide- selective vasodilator of vessels
that perfuse well ventilated lung zones
Extracorporeal membrane oxygenation
(ECMO)-Veno-arterial bypass which
supports gas exchange and oxygenation
Summary of Recommendations
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