Ventilation strategies in ards rachmale

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  • PLATEAU PRESSURE GOAL: ≤ 30 cm H2O Check Pplat (0.5 second inspiratory pause), at least q 4h and after each change in PEEP or VT. 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. If Pplat < 30 and breath stacking or dys-synchrony occurs: may increase VT in 1ml/kg increments to 7 or 8 ml/kg if Pplat remains < 30 cm H2O.
  • Mortality=death before discharge home and was breathing without assistance
  • PT ideal body weight approx: 52.3- 6 ml/kg: 294, 8 ml/kg: 456
  • Ac/Vt 370/35/ 36/30/peep 20/ AC/ Vt 370/33/Pif 50/PAP40/PlP:37PEEP: 22 VC+/320/35/I time 1.00/ 40/36/22 A long TI, a high TI/TTOT, and a low mean inspiratory flow all promote ventilation with an inverse I:E ratio. Long pause times favor the recruitment of previously collapsed or flooded alveoli and offer a means of shortening expiration independent of rate and mean inspiratory flow

Transcript

  • 1. Ventilation Strategies in ARDS MICU-ER Joint Conference Dr. Rachmale, Dr. Prasankumar 12/3/08
  • 2. Initial ICU Management
    • 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/PLP-30/ peep- 7
    • Pao2/Fi02:60
  • 3. 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)
  • 4. NIH-NHLBI ARDS Network Cause of Lung Injury NHLBI ARDS Clinical Trials Network. N Engl J Med. 2004.
  • 5. Mortality 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
  • 6. Stages of ARDS
  • 7. 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”
  • 8. 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
  • 9. Minimizing VILI- Plateau pressure goals
    • 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
  • 10. Mortality: low vs. traditional tidal volume Low tidal volume Traditional tidal volume RRR=22 % ARR=8.8 % NNT=12 p=0.007 ARDSNet. NEJM 2000;342:1301.
  • 11. PEEP in ARDS
    • 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 0.5 0.6 0.7 0.7 0.7 0.8 0.9 0.9 0.9 1.0 PEEP 5 5 8 8 10 10 10 12 14 14 14 16 18 18-24
  • 12. 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 H 2 O for 1-2 minutes
      • Intermittent sighs or Extended sighs
    • Can cause Hypotension, pneumothorax, Needs Experience
  • 13. 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
  • 14. Management continued
    • 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
  • 15.  
  • 16.  
  • 17. Management continued
    • 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-
  • 18. Hospital Course
    • During entire 25 day course Fio2 requirements could not be lowered to less than 80%, the least PEEP was 14
    • Peak and plateau pressure remained high
    • Septic shock  MSOF  death
  • 19. Alternative strategies
    • 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
  • 20.
    • Limited VT 6 mL/kg PBW to avoid alveolar distension
    • End-inspiratory plateau pressure < 30 cm H 2 O
    • Adequate end expiratory lung volumes utilizing PEEP and higher mean airway pressures to minimize atelectrauma and improve oxygenation
    • Consider recruitment maneuvers
    Summary of Recommendations