We rightly like to avoid intubation in COPD exacerbations. Extracorporeal CO2 removal or ‘pulmonary dialysis’ has been around for a while and many feel it is beneficial in COPD (eg this case) but who is it best used for?
In an Italian matched cohort study Del Sorbo and colleagues looked at 200 patients with an exacerbation of COPD treated with NIV (up to 90yrs old!).
They focused specifically on the subset of 89 patients at risk of NIV failure, defined as:
- 2 hours of continuous NIV
- arterial pH less < 7.30
- Paco2 greater than 20% of baseline
- respiratory rate >30 or use of accessory muscles or paradoxical abdominal/chest movement.
However only 25 of the 89 ‘at risk’ patients intended for ECCO2R actually ended up with it, largely due to refusal of consent. In these 25 femoral vein (14F double lumen) pumped VV ECCO2R (?a converted haemofilter!) was popped in and heparinization commenced. (ECCO2R v ECMO diagram for the uninitiated)
If after 2 hours they had a pH <7.25, rising oxygen requirement, were haemodynamically unstable or comatose they would be intubated.
The NIV-only control group was taken from 2 previous studies and propensity matched for ‘at risk’ criteria as well as other sensible parameters (APACHE, prior respiratory function, age etc). 21 matched patients were found.
Primary outcome measure was intubation by 28 days.
Results:
3 of the ECCO2R ‘v’ 7 of the standard NIV group were intubated, ie RRR of over 70% and an ARR of 21%. Of course this was not statistically significant.
The ECCO2R group had better pH, CO2, oxygenation and respiratory rate.
But half the patients had adverse events. These were mainly circuit issues but haemorrhage was a problem in 4 of the 25.
There was a striking trend towards mortality 8% for ECCO2R, ‘v’ 35% for NIV alone. Fewer ICU days too.
So, potentially useful in 1 in 8 COPD exacerbations requiring NIV, ECCO2R is not without risk but may avoid intubation or even be life saving. This now needs a closer look. Equipoise was clearly an issue in this study, and now surely shouldn’t be? Parallel effort to improve prediction of NIV failure is probably also warranted.
Update June 2015 – read this systematic review on the topic. Caution advised!
