Saturday, October 22, 2011

A Third of TPA Patients Do Not Have Stroke

...but they almost all do well!  Only 5.1% of patients without stroke who receive TPA end up with intracerebral hemorrhage - so it's OK that we give TPA to a ton of patients without a confirmed diagnosis of stroke, right?

This is a retrospective Finnish registry study of 1,104 consecutive TPA patients enrolled in a prospective cohort.  Of these, 119 had basilar artery occlusion, which is angiographically proven prior to treatment, and are excluded from their analysis, and a couple others were excluded for other reasons.  This left 985 patients who were initially diagnosed with ischemic stroke, and, eventually, 14 of those patients were diagnosed as a stroke mimic such as migrane, epilepsy, or a demyelinating disorder.  The authors then go on to say that stroke mimics such as these accounted for a mere 1.4% of all TPA patients, and none of them had ICH.

But, this isn't exactly a true reading of their data.  The authors also state that 275 of their patients had "neuroimaging negative ischemic stroke", which is to say, their follow-up MRI detected no sign of infarct.  Now, there is a false-negative rate on DWI MRI for stroke, but it's in the range of 5% for acute infarcts, and generally involves small lacunar, small cortical, and some posterior circulation strokes.  Not only that, it's reasonable to suggest that around 40% of TIAs actually have DWI or FLAIR sequence abnormalities as well.

So, some of their "neuroimaging negative ischemic stroke" group probably does have ischemic stroke with false negative MRI - but not 30% of the study population.  And, some of their neuroimaging positive group is likely false positive from TIA as well.  These numbers for stroke mimics are also far below other reported case series, which have estimated 10-30% incidence, depending on whether TIAs are included.

I absolutely cannot fathom this line of reasoning and distortion Neurology is developing in justify recklessly pushing TPA onto a larger population.

"Stroke Mimics and Intravenous Thrombolysis"
http://www.ncbi.nlm.nih.gov/pubmed/22000770

Thursday, October 20, 2011

Preventing Mechanical Ventilation in Newborns

This is lovely article regarding the treatment of respiratory distress in newborns.  It is not a new concept to use surfactant in clinically indicated situations to improve ventilation in the newborn in distress - however, the typical treatment involves endotracheal intubation and mechanical ventilation prior to application.  This is a randomized, controlled trial of surfactant administration prior to mechanical ventilation.

This involves 220 preterm infants in Germany who were selected for the trial, essentially, if they were on CPAP requiring more than 30% inspired O2.  In the intervention group, patients received intratracheal surfactant if stable on CPAP and 30% O2.  Outcome measures were the portion of patients mechanically ventilated at any time or at day 2 or 3 after birth.  Minimal differences between groups, although the control group was a few grams lighter at birth.

Overall, 33% of all intervention infants required mechanical intervention vs. 73% of the control group.

Simple takeaway - surfactant isn't just useful after intubation, but may also prevent mechanical ventilation.

"Avoidance of mechanical ventilation by surfactant treatment of spontaneously breathing preterm infants (AMV): an open-label, randomised, controlled trial"
www.ncbi.nlm.nih.gov/pubmed/21963186

Wednesday, October 19, 2011

Ultrasound In Undifferentiated Infant Vomiting

Is there anything ultrasound can't do?  Trauma, vascular access, undifferentiated abdominal pain - and another nice case report for vomiting in children.

These authors are using ultrasound in the projectile-vomiting infant looking at the pylorus, and, after finding a normal pylorus, they scan the rest of the abdomen.  Lo and behold, they identify intussusception.  I am not entirely certain I would be able to well-identify the pylorus, but I can definitely see potentially noting the intussusception.  The authors include several nice images as teaching points.

As the barriers to routine ultrasound use in the ER decrease, hopefully we will all become more facile with using it in many more clinical situations.

"Use of Emergency Ultrasound in the Diagnostic Evaluation of an Infant With Vomiting"
www.ncbi.nlm.nih.gov/pubmed/21975504

Monday, October 17, 2011

Hypertonic Saline In Cardiac Arrest

There is a physiologic phenomenon observed in animal studies that a small increase in plasma osmolarity using hypertonic saline increases microperfusion, including myocardial and cerebral blood flow.  Therefore, in theory, hypertonic saline administration during resuscitation from cardiac arrest should be efficacious in improving survival and neurologic outcome.

These authors conduct a randomized prospective trial in which they prove that 100 patients in each arm is not enough to make valid claims about a secondary endpoint for which the study was not designed to evaluate.  There is no difference between groups in mortality - and not even non-significant trends - but a small, significant, absolute difference in neurologic impairment, 4.9% without neurologic impairment in the control group and 13% in the intervention group.

So, another study suggesting further study is needed.  If anything, it demonstrates how impossibly hard it is to evaluate treatments in the heterogenous population of out-of-hospital cardiac arrest, and to ensure internal and external validity.

"Randomised study of hypertonic saline infusion during resuscitation from
out-of-hospital cardiac arrest."

Sunday, October 16, 2011

Stroke After-Care Is Far More Important

Somewhere in the rush to but up billboards and focus the medical establishment on experimental revascularization interventions for acute stroke (e.g., time is brain), we've overlooked what truly matters - follow-up care after the ischemic event.  This is a lovely study that reminds us of what we probably knew once, but have forgotten - that even in the absence of acute therapy, simple protocols to prevent fever, prevent hyperglycemia, and prevent aspiration pneumonia lead to profound differences in the number of patients with zero or minimal disability after stroke.

This is a prospective interventional study in which acute stroke units in New South Wales Australia were randomized to either no protocolized intervention, or an intervention with nursing protocols named above.  At the end of the three-year intervention period, 42% of the control group had mRS 0 or 1 at 90 days, and 58% of the intervention group had mRS 0 or 1 at 90 days.  There were small differences in the type of stroke, education level, and prior ability to work that probably favored the intervention group, but the differences at baseline were far smaller than the magnitude of the treatment effect.  In short, a basic nursing protocol intervention improved outcomes more than any other intervention for acute stroke.

"Implementation of evidence-based treatment protocols to manage fever, hyperglycemia, and swallowing dysfunction in acute stroke (QASC): a cluster randomised controlled trial."
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)61485-2/fulltext