Dr. Roy Brower is one of the original ARDSnet authors that brought Low Tidal-Volume ventilation to the masses.  We asked him to speak his mind on what he thinks we should do once the traditional ARDSnet goals no longer apply.
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Evidence behind ARDSnet protocol and beyond
- EXPRESS PEEP Trial
- Raise PEEP until Pplat = 28-30
- No mortality benefit, improved lung function, and reduced the duration of mechanical ventilation
- High vs. Low PEEP in ALI Meta-analysis
- Higher PEEPÂ associated with improved survival among the subgroup of patients with ARDS
- PaO2/FiO2 < 200
- Neuromuscular blockade for 48 hours
- Improved 90 day survival
- Reduced time off ventilator
- PaO2/FiO2 < 150
- Used cisatracurium x 48 hours
- Proning WORKS
- Minimal cost intervention
- Proned for 16 hours, supine for 6 hours
- Decreased 28-day and 90-day mortality
What else should you consider with a high Plateau Pressure?
- We actually have no idea what the best Pplat is for each patient
- The lungs are surrounded by a number of different variable forces, that contribute to the plateau pressure
- Abdominal pressure (estimated by bladder pressure)
- Force of the chest wall, thoracic cavity on the lungs
- Pleural effusions
- Pneumothorax
- Lung diseases
- Are you measuring the Pplat correctly?
- Don’t be fooled, the real plateau can appear to be falsely elevated if the patient is making an inspiratory effort at the end of your end-inspiratory hold. Â Look at the waveform!!
Troubleshooting a Pplat > 30
- Check to see if the patient is a PEEP responder (Lower the PEEP)
- Stop worry about it! (as long as you can justify the higher Pplat based on the above variables)
- Lower the VT to < 4 cc/kg IBW – Mechanically vented patients rarely die from a high PaCO2
- We probably should stop using the Oscillator – Reason 1, Reason 2
Problem 2:Â What about ECMO?
- Rationale makes sense
- Not completely clear if ECMO is any better
- The clinical trials need to be done to prove mortality/safety benefit
References
- Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. The Acute Respiratory Distress Syndrome Network. N Engl J Med. 2000;342(18):1301-8.
- Hager DN, Krishnan JA, Hayden DL, Brower RG. Tidal volume reduction in patients with acute lung injury when plateau pressures are not high. Am J Respir Crit Care Med. 2005;172(10):1241-5.
- Grasso S, Stripoli T, De michele M, et al. ARDSnet ventilatory protocol and alveolar hyperinflation: role of positive end-expiratory pressure. Am J Respir Crit Care Med. 2007;176(8):761-7.
