Friday, April 27, 2012

Lactate Clearance and ScvO2 Goals in Sepsis


Early goal-directed sepsis care is successful - but no one can say precisely what makes it successful.  Hawthorne effect?  Early antibiotics appear to have uncertain association with better outcomes.  Is it the blood?  Is it meeting the central venous oxygenation goal of >70%?

Other studies have shown equivalency in outcomes while performing serial lactic acid measurements, and this is another study in the same vein.  203 patients form the analysis cohort, in which 93 received management decisions based on lactate clearance and 110 which received management decisions based on the ScvO2.  All included patients had both values measured simultaneously, but were blinded to the opposition.

And, this is another study where the two measures are different but similar - which is probably why the analysis is so convoluted.  Of the 203 enrolled, 175 either fortuitously or by design met the ScvO2 goal, while 178 met the lactate clearance goal.  Meeting the ScvO2 goal led to a death rate of 21% and meeting the lactate clearance goal led to a death rate of 17%.  There was no difference in therapeutic interventions between the ScvO2 goal group and the lactate clearance group.

However, if you met the lactate clearance without meeting the ScvO2 goal, you had an 8% (2/25) mortality, while the ScvO2 group that didn't clear lactate had a 41% mortality (9/22).  Unfortunately, there were a number of baseline differences between the groups, and it's hard to draw any conclusions or hypotheses from this finding.  It's also clear they didn't identify any specific interventions that improved survival in their cohort - and, more appropriately, simply observed that poor lactate clearance simply portends a worse outcome, without any specific recommendation on how to address it.

"Prognostic Value and Agreement of Achieving Lactate Clearance or Central Venous Oxygen Saturation Goals During Early Sepsis Resuscitation"

Wednesday, April 25, 2012

Most Severe Mechanism Children Don't Need Head CTs


The PECARN group has published a set of criteria that identify children at very low risk for significant traumatic injury.  This is publicly available and an excellent decision instrument to enhance your clinical judgement.  But, the problem is, with excellent sensitivity, the specificity is weak - such that a great number of patients who fail to meet low-risk criteria will still have good outcomes.

So, this is a follow-on study attempting to determine whether the severe mechanism portion of the decision instrument was predictive of significant TBI, or whether scans could be avoided if mechanism was the only positive feature in their decision instrument.  And, yes, a severe injury mechanism in isolation - at least in the 35% of their cohort who received a head CT - had only a 0.3% chance of significant injury in age <2 years and 0.6% chance of significant injury in age >2 years.  Severe injury mechanisms associated with additional PECARN criteria, however, had 4% and 6% incidence of TBI, depending on age.

Probably the most important aspect of these numbers is they allow for a better discussion of risks with parents and families.  While 1 in 150 or 1 in 300 sound like pretty good odds, when you practice long enough, those odds will catch up with you.  Even with severe mechanism and additional features, 19 of 20 CTs will be negative - you can still make a reasonable case for observation rather than knee-jerk scanning.

"Prevalence of Clinically Important Traumatic Brain Injuries in Children With Minor Blunt Head Trauma and Isolated Severe Injury Mechanisms"

Monday, April 23, 2012

Mobile Stroke Units - Probably Not Helpful

Door to needle times too long?  Well, take the needle to the patient, then.


This is an interesting idea that, unfortunately, probably isn't a good idea.  They loaded a CT scanner, a stroke physician, a paramedic, and a mobile laboratory into a truck, and sent it out to meet acute stroke patients in the field.  The primary endpoint of the study - alarm to thrombolysis time - was great, with a mean time from alarm to therapy decision of 35 minutes.


The authors are very excited about the concept - as they feel the accelerated time scale in terms of acute stroke thrombolysis represents a paradigm shift in management.  Unfortunately, the patient-oriented outcomes - which were not part of the primary endpoint - don't support their enthusiasm.


All their safety and therapeutic outcomes are underpowered, but, out of their 47 intervention patients and 53 control (in-hospital thrombolysis) patients, 12 vs. 6 were treated stroke mimics and 3 vs. 0 were dead within 7 days.  Comorbidities and stroke severity should have favored the intervention group, so, these outcomes are surprising.  But, it is underpowered, so more data is needed.


"Diagnosis and treatment of patients with stroke in a mobile stroke unit versus in hospital: a randomised controlled trial."
http://www.ncbi.nlm.nih.gov/pubmed/22497929