ARDSNet Mechanical Ventilation Protocol

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INCLUSION CRITERIA: Acute onset of

1. PaO2/FiO2 ≤ 300 (corrected for altitude)
2. Bilateral (patchy, diffuse, or homogeneous) infiltrates consistent with pulmonary edema
3. No clinical evidence of left atrial hypertension

PART I: VENTILATOR SETUP AND ADJUSTMENT

1. Calculate predicted body weight (PBW)
   • Males = 50 + 2.3 [height (inches) - 60]
   • Females = 45.5 + 2.3 [height (inches) -60]
2. Select any ventilator mode
3. Set ventilator settings to achieve initial VT = 8 ml/kg PBW
4. Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW.
5. Set initial rate to approximate baseline minute ventilation (not > 35 bpm).
6. Adjust VT and RR to achieve pH and plateau pressure goals below.

OXYGENATION GOAL: PaO2 55-80 mmHg or SpO2 88-95%
Use a minimum PEEP of 5 cm H2O. Consider use of incremental FiO2/PEEP combinations such as shown below (not required) to achieve goal.

Lower PEEP/higher FiO2

FIO2	0.3	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

Higher PEEP/lower FiO2

FIO2	0.3	0.3	0.3	0.3	0.3	0.4	0.4	0.5	0.5	0.5-0.8	0.8	0.9	1.0	1.0
PEEP	5	8	10	12	14	14	15	16	18	20	22	22	22	24

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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.

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pH GOAL: 7.30-7.45
Acidosis Management: (pH < 7.30)

• If pH 7.15-7.30: Increase RR until pH > 7.30 or PaCO2 < 25 (Maximum set RR = 35).
• If pH < 7.15: Increase RR to 35.
  If pH remains < 7.15, VT may be increased in 1 ml/kg steps until pH > 7.15 (Pplat target of 30 may be exceeded).
  May give NaHCO3
• Alkalosis Management: (pH > 7.45) Decrease vent rate if possible.

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I: E RATIO GOAL: Recommend that duration of inspiration be < duration of expiration.

PART II: WEANING

A. Conduct a SPONTANEOUS BREATHING TRIAL daily when:

1. FiO2 ≤ 0.40 and PEEP ≤ 8 OR FiO2 < 0.50 and PEEP < 5.
2. PEEP and FiO2 ≤ values of previous day.
3. Patient has acceptable spontaneous breathing efforts. (May decrease vent rate by 50% for 5 minutes to detect effort.)
4. Systolic BP ≥ 90 mmHg without vasopressor support.
5. No neuromuscular blocking agents or blockade.

 

B. SPONTANEOUS BREATHING TRIAL (SBT):
If all above criteria are met and subject has been in the study for at least 12 hours, initiate a trial of UP TO 120 minutes of
spontaneous breathing with FiO2 < 0.5 and PEEP < 5:

1. Place on T-piece, trach collar, or CPAP ≤ 5 cm H2O with PS < 5
2. Assess for tolerance as below for up to two hours.
   1. SpO2 ≥ 90: and/or PaO2 ≥ 60 mmHg
   2. Spontaneous VT ≥ 4 ml/kg PBW
   3. RR ≤ 35/min pH ≥ 7.3
   4. No respiratory distress (distress= 2 or more)
      • HR > 120% of baseline
      • Marked accessory muscle use
      • Abdominal paradox
      • Diaphoresis
      • Marked dyspnea
3. If tolerated for at least 30 minutes, consider extubation.
4. If not tolerated resume pre-weaning settings.

Definition of UNASSISTED BREATHING(Different from the spontaneous breathing criteria as PS is not allowed)

1. Extubated with face mask, nasal prong oxygen, or room air, OR
2. T-tube breathing, OR
3. Tracheostomy mask breathing, OR
4. CPAP less than or equal to 5 cm H20 without pressure support or IMV assistance.