Archive for the ‘2010’ Tag

The Pinocchio Effect

An interesting editorial published a couple of months ago in Anaesthesia by Neil Soni. It adds to the growing disquiet that our understanding of disease, and attempts to find effective remedies, are being hampered by the tendency to treat all organ failures equally. I agree that there seems little reason to believe that meningococal sepsis in an 18 year old will behave the same as peritonitis in an 80 year old, nor that ARDS following pancreatitis is the same as that following FFP. However, these syndromes were designed partly to make research into rare presentations possible. If we define patients according to causative factor and co-morbidity how are we ever to recruit enough to power even the most basic trial ?

ARDS, acronyms and the Pinocchio effect. Soni N.Anaesthesia. 2010 Oct;65(10):976-9. doi: 10.1111/j.1365-2044.2010.06508.x.PMID: 21198467

NMB in Early ARDS.

A fascinating study from the NEJM.

Neuromuscular Blockers in Early ARDS. Papazian, L et al. NEJM. Vol 6, 12, 2010.

This RCT gave a 48 hr infusion of cis-atricurium to early (<24hrs) ARDS patients. It is the first study to show a mortality difference in this condition since ARDSnet a decade ago (although caution is required as it was underpowered). Whilst it is likely that a large proportion of the population included in this study (early, severe ARDS) will already be on NMB to aid ventilation, there has up until now been an assumption that this therapy was a necessary harm (due to the risk of critical illness polyneuropathy and subsequent slow weaning). This study questions that wisdom, showing both a reduction in adjusted mortality at 90 days (although not at 28) and no increase in the risk of CIPN. The results need to be taken with caution, but are certainly interesting and if confirmed may offer an important advance. There is further detailed analysis of the paper in the presentation ‘Atricurium ARDS’ in the blue box. Remember that restrictions on comments have been lifted on Critical Insight, no sign in required – so let us know your opinions.

Oxygen – too much of a good thing ?

We’ve known for sometime that high inspired oxygen fractions (>0.8) are associated with atelechasis (and decruitment / shunt) and lung injury and suspected that hyperoxia also leads to the generation of toxic oxygen free radicals, which may have deleterious effects in other pathologies. A recent paper adds to this story;

Association between arterial hypoxia following resuscitation from cardiac arrest and In Hopsital mortality. Hope, J et al. JAMA. 2010;303(21):2165-2171 (doi:10.1001/jama.2010.707).

This paper has been appraised by a colleague, Paul Townsley, and you can download his presentation from the blue box on the right. Although the methodology has some potential flaws (which is probably inevitable), the paper provides evidence of definite harm of hyperoxia in ischemic brain injury.

Of course, there is an alternative weight of evidence of the harm associated with even short periods of desaturation in traumatic brain injury (and presumably also brain injury from poor perfusion). How to square this circle? The devil as always is in the detail. Controlling hyperoxia is probably important, but whether the benefits of avoiding hyperoxia outweigh the additional risk of periods of desaturation, or how often those periods occur within patient populations, is unknown. There is sufficient evidence to warrant a carefully designed RCT in the post resuscitation phase, (and maybe also in ARDS while we’re at it).

SOAP II – That’s cleaned that up then.

Dopamine has been the vasopressor of choice in septic patients in continental europe historically, although this may be changing. Dopamine has theoretically beneficial effects in maintaining splancnic and renal perfusion although in the SOAP trial (observational) suggested that there was an excess of mortality of dopamine treated patients. The old story of “renal dose dopamine” having an additional effect over and above the improvement in perfusing pressure has been discredited, but this result suggests a harmful signal over and above noradrenaline (the preferred agent in the UK).

Comparison of dopamine and norepinephrine in the treatment of shock. De Backer DN, et al. N Engl J Med. 2010 Mar 4;362(9):779-89.
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BIS – magic prediction post arrest ?

A fascinating paper very well reviewed by Dr. James Dawson at the QMC journal club;

The bispectral index and suppression ratio are very early predictors of neurological outcome during therapeutic hypothermia after cardiac arrest Intensive Care Med. 2010 Feb;36(2):281-8. Epub 2009 Oct 22. Continue reading