Saturday, August 13, 2011

We Still Can't Predict Cardiac Outcomes in Syncope


The authors of this article claim that the San Francisco Syncope Rule - which we've already put out to pasture - has simple EKG criteria that "can help predict which patients are at risk of cardiac outcomes".

And, they're only possibly partly right.  Out of the 644 patients in their cohort they followed for syncope, they had 42 cardiac events within their 7-day follow-up period.  Of those 42, 36 met the criteria for "abnormal EKG".  If you had a completely normal EKG, it was 6 out 428 that had a cardiac event, which gave them a 99% NPV upon which they base the quoted statement above.

But the positive criteria wasn't adequately predictive enough to be helpful in making hospitalization decisions - 216 patients had abnormal EKGs, but only 36 had a cardiac outcome.  And then, there are significant differences in the patients who had abnormal EKGs, and even more differences with the patients who had cardiac outcomes - the cardiac outcome cohort had an average age of 78.6 compared to the noncardiac outcome cohort average age of 61.0, with probably even more comorbid differences they don't tell us about.

So, a normal EKG is probably helpful in making your decision - but being younger and healthier probably accounts for more of the differences between their groups.

"Electrocardiogram Findings in Emergency Department Patients with Syncope"
www.ncbi.nlm.nih.gov/pubmed/21762234

Thursday, August 11, 2011

CT Is No Longer Adequate To Clear C-Spine

The insanity never stops.  It's a good thing MRI is becoming increasingly available, because the more papers like this are published in major journals, the more we're going to be stuck following every possible outcome to it's bitterest end with the strongest microscope we have.

There a lots of problems with using this paper to change practice - of their 9152 patients undergoing CT for trauma, 741 had persistent midline tenderness leading towards MRI.  Of those 741, only 174 were enrolled for a variety of reasons.  And this study doesn't tell us enough useful information to help distinguish the characteristics of the 78 patients in whom an injury was detected to help us differentiate them from the patients in whom no injury was detected.

But the fact remains, they identified serious injuries on MRI in patients who had negative CTs - and not just obtunded, intubated, polytrauma patients like in the other studies.

Just one more thing to worry about.

"Cervical Spine Magnetic Resonance Imaging in Alert, Neurologically Intact Trauma Patients With Persistent Midline Tenderness and Negative Computed Tomography Results"
http://www.ncbi.nlm.nih.gov/pubmed/21820209

Wednesday, August 10, 2011

The Slow Death of the Lumbar Puncture

As modern CT scanners become more sensitive, the ability of scanners to discriminate smaller and small abnormalities - such as spontaneous aneurysmal subarachnoid hemorrhage - continues to increase.  This BMJ paper makes another case for forgoing lumbar puncture in patients with a negative CT scan.

Specifically, they say that all the SAH in their cohort was picked up by a 3rd generation scanner as long as the scan was performed within six hours of headache onset.  Unfortunately, this is another one of those studies that uses follow-up as a proxy for the gold standard evaluation - only half of their enrolled cohort underwent lumbar puncture.  They followed up their patients for six months, but survival at six months doesn't rule out pathology, it only rules out death from that specific pathology, and only if an autopsy was performed.

But, CT scan is starting to get close to the point where the false negatives of CT are equivalent to the false positives of the lumbar puncture - and I would imagine the costs and harms to the patient begin to approach equivalence.  It definitely changes the equation for your patients when you come back with a negative CT scan and your patient wants to know what the chances are they really need this lumbar puncture.

"Sensitivity of Computer Tomography Performed Within Six Hours of Headache For Diagnosis of Subarachnoid Haemorrhage: Prospective Cohort Study"
www.ncbi.nlm.nih.gov/pubmed/21768192

Monday, August 8, 2011

High-Risk Discharge Diagnoses

Good news - only 0.05% of your discharged patients will meet an untimely end within 7 days of the Emergency Department visit.  Not a frightening number, but definitely enough to keep you on your toes.

It's a retrospective Kaiser Health System cohort of 728,312 visits across two years, and the authors calculated the base rate of 50 per 100,000, as well as looking at other features and discharge diagnoses that increased the OR for death within 7 days.  And, even the sickest, most elderly have OR that are low enough that you're still going to have good outcomes the overwhelming preponderance of the time.  Age greater than 80 gives an OR of 10.6 and a score >3 on the Charlson Comorbidity Index gives an OR of 6.7.  As for the diagnoses they found that are most highly associated with bad outcomes - the only two with OR great than 5 are noninfectious lung disease (OR 7.1) and renal disease (OR 5.6).  These are kind of interesting buckets of diagnoses, specifically in the sense regarding how nonspecific they are - which the authors attribute to diagnostic uncertainty.  I.e., the reason why patients had bad outcomes with "noninfectious lung disease" is because clinicians missed finding the specific morbid diagnosis in these patients.

I don't think this is practice-changing news, since these rates are so low in general that additional testing and hospitalization will harm more people than these missed diagnoses - but it's an interesting number crunch article.

"Patterns and Predictors of Short-Term Death after Emergency Department Discharge"

Sunday, August 7, 2011

Against Medical Advice

This is a nice review article that shows a mix of different issues associated with signing a patient out AMA.  It's a strange practice environment we have here, where EM is turning into an increasingly customer-centric practice specialty - yet unless we have airtight documentation, our customers can litigate against us for the choices they make.

In principle, our patients have the autonomy to make their own decisions - but our cultural values have drifted away from accepting responsibility for our actions.  To best protect ourselves, the authors recommend using a specific AMA form - not because having the patient's signature on a form confers any extra legal protection, but because it's a structured document that helps remind clinicians to document the two key elements of the AMA:  that the patient had medical capacity to make the decision, and that the patient was adequately informed of the risks.   After you satisfy both those conditions, the key is simply complete documentation in the medical record, and you should be afforded some protection given the patient has now terminated the legal duty to treat and assumed the risk for further poor outcomes.

"The Importance of a Proper Against-Medical-Advice (AMA) Discharge"
www.ncbi.nlm.nih.gov/pubmed/21715123