Mechanical ventilation protocol
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Vishnu Vardhan Serla M.B.B.S. [2]
Protocol
Inclusion Criteria
- PaO2 <= 300 ( corrected for altitude)
- Bilateral (patchy, diffuse or homogenous) infiltrates consistent with pulmonary edema
- No clinical evidence of left atrial hypertension
Ventilator Setup
- Calculate predicted body weight. It is calculated using the formula
- Males = 50 + 2.3[height(in inches)-60]
- Females = 45.5 + 2.3[height(in inches)-60]
- Selecting the ventilator mode
- Set ventilator settings to achieve initial Vt = 8 ml/kg of predicted body weight
- Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW.
- Set initial rate to approximate baseline minute ventilation (not > 35 breaths per minute).
- Adjust VT and respiratory rate to achieve pH and plateau pressure goals below.
Oxygenation Goal
- PaO2 55-80 mmHg or SpO2 88-95% is the goal.
- Use a minimum PEEP of 5 cm H2O.
- Consider use of incremental FiO2/PEEP combinations 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 | 16 | 16 | 18 | 20 | 22 | 22 | 22 | 24 |
Plateau Pressure Goal
- Plateau pressure goal(Pplat) is <= 30 cm H2O
- Check Pplat every 4th hourly after change in PEEP ot VT
- If Pplat > 30 cm of H2O
- Decrease VT by 1ml/kg
- If Pplat < 25 cm of H2O and VT < 6ml/kg
- Increase VT by 1ml/kg unbtil Pplat > 25 cm H2O or VT = 6 ml/kg
- If Pplat < 30 cm and breath stacking or dys-synchrony occurs
- Increase VT in 1 ml/kg increments to 7 or 8 ml/kg, if Pplat remains <=30 cm of H2O
PH Goal
- pH should be maintained at 7.30 - 7.45
- If pH is less than 7.30 (acidosis)
a. Range of 7.15 - 7.30
- Increase respiratory rate until pH > 7.30 or PaCO2
- Maximum rate can be 35
b. Less than 7.15
- Increase respiratory rate to 35
- VT can be increased in 1 ml/kg until pH >7.15 (Pplat target of 30 may be exceeded)
- Bicarbonate can be given
- If pH is more than 7.45 (alkalosis)
- Decrease the ventilation rate if possible
I:E Ratio Goal
Recommend that duration of inspiration be less than equal to duration of expiration.
Weaning
A spontaneous breathing trial has to be done daily when
- FiO2 ≤ 0.40 and PEEP ≤ 8.
- PEEP and FiO2 ≤ values of previous day.
- Patient has acceptable spontaneous breathing efforts. (May decrease vent rate by 50% for 5 minutes to detect effort.)
- Systolic BP ≥ 90 mm Hg without vasopressor support.
- No neuromuscular blocking agents or blockade.
Spontaneous Breathing Trial
If all above criteria are met and patient has been in the observed for at least 12 hours, initiate a trial of upto 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.
a. SpO2 ≥ 90: and/or PaO2 ≥ 60 mm Hg b. Spontaneous VT ≥ 4 ml/kg predicted body weight c. RR ≤ 35/min d. pH ≥ 7.3 e. 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.