More Futility: Apneic Oxygenation?

Here’s another pendulum swing to throw into the gears of medicine – an apparent failure of apneic oxygenation to prevent hypoxemia during intubation in the Emergency Department. Apneic oxygenation – passive oxygenation during periods of periprocedural apnea – seems reasonable in theory, and several observational studies support its use. However, in a randomized, controlled ICU setting – the FELLOW trial – no difference in hypoxemia was detected.

This is the ENDAO trial, in which patients were randomized during ED intubation, with a primary outcome of mean lowest oxygen saturation during or immediately following. These authors prospectively enrolled 206 patients of 262 possible candidates, with 100 in each group ultimately qualifying for their analysis. The two groups were similar with regard to initial oxygen levels, pre-oxygenation levels, and apnea time. Then, regardless of their statistical power calculations and methods, it is fairly clear at basic inspection their outcomes are virtually identical – in mean hypoxemia, SpO2 below 90%, SpO2 below 80%, or with regard to short-term or in-hospital mortality. In the setting in which this trial was performed, there is no evidence to suggest a benefit to apneic oxygenation.

It is reasonable to note all patients included in this study required a pre-oxygenation period of 3 minutes by 100% FiO2 – and that oxygen could be delivered by bag-vale mask, BIPAP, or non-rebreather with flush rate oxygen. These are not necessarily equivalent methods of pre-oxygenation, but, at the least, the techniques were not different between groups (>80% NRB). It is reasonable to suggest passive oxygenation may be more beneficial in those without an adequate pre-oxygenation period, but it would certain be difficult to prospectively test and difficult to anticipate a clinically important effect size.

Adding complexity to any procedure – whether with additional monitoring and alarms or interventions of limited efficacy – adds to the cognitive burden of the healthcare team, and probably has deleterious effects on the most critical aspects of the procedure. It is not clear that apneic oxygenation reliably improves patient-oriented outcomes, and does not represent a mandatory element of rapid-sequence intubation.

“EmergeNcy Department use of Apneic Oxygenation versus usual care during rapid sequence intubation: A randomized controlled trial”
http://onlinelibrary.wiley.com/doi/10.1111/acem.13274/full

The Futility of NSAIDs for Back Pain?

This article filled with reproach for non-steroidal anti-inflammatories was highlighted in a New England Journal of Medicine Journal Watch and on Twitter – a wistful treatise remarking on the general ineffectiveness of pharmacologic analgesics. “Nothing works!” accompanied by a general gnashing of teeth and writhing on invisible flames.

But – does this meta-analysis actually reach such a conclusion? Examine the first few words in their conclusion:

NSAIDs are effective for spinal pain …

Off to a good start! But, the catch:

… but the magnitude of the difference in outcomes between the intervention and placebo groups is not clinically important.

These authors pool the results of 35 randomized, placebo-controlled trials for “spinal pain”, which is to say undifferentiated pain relating anatomically to any part of the spine. These trials comprised 6,065 participants – or, if you do the math, an average of 173 patients per trial, nearly all of them performed over a decade ago. The pooled effects of these trials all favored NSAIDs – but, as the authors mention, the absolute magnitude of effect on pain scales was a the edge of their threshold for clinical significance. The authors defined a difference of 10 points on a 100-point scale as clinically important, but most of their pooled results landed between -7 and -16, favoring NSAIDs over placebo. With these small samples, generally moderate GRADE quality, and moderate to high heterogeneity between the pooled results, there is a lot of fuzziness around their ultimate conclusion.

These authors do many, other, exploratory analyses, and it is reasonable to suggest the limitations inherent to each render any conclusions unreliable. Adverse events, as reported, were similar between groups – excepting for increased gastrointestinal adverse events, most of which were non-serious. The authors report this difference as a relative risk of 2.5 for GI side effects in their comparison, but the absolute differences are on the order of an excess of 1 in 100.

This is probably much ado about nothing. Their perspective is not inaccurate, per se, but these trials do find a consistent benefit to NSAIDs. The value judgment here on clinical effectiveness probably misses the mark, particularly considering these are inexpensive, readily available, with few adverse effects in short-term use. I would probably argue it is easier to defend a position they still have utility in multi-modal pain control regimens, rather than to conclude they be consigned to the rubbish bin.

“Non-steroidal anti-inflammatory drugs for spinal pain: a systematic review and meta-analysis”

https://www.ncbi.nlm.nih.gov/pubmed/28153830

 

Predicting Treatment Failure in AOM

Like most infectious diseases, acute otitis media generally breaks down into three cohorts. There are viral infections, for which early antimicrobial therapy is virtually, by definition, unhelpful. Then, there are true bacterial infections – many of which resolve without substantial morbidity regardless of antimicrobial treatment, and those which require antimicrobial therapy to prevent such. The trick, and where modern medicine typically fails miserably, is rapidly predicting into which of these cohorts a patient may fall – a conundrum leading to the epidemic of antibiotic overuse.

This is a secondary analysis of a pediatric AOM trial, first published in the New England Journal of Medicine, looking at which patients were more likely to potentially fail conservative treatment. The intervention arm received amoxicillin/clavulanate, and treatment failure occured in 31.7% of children – vastly favoring the antibiotic arm – 44.9% vs. 18.6%. In theory, this exaggerated treatment effect might help better illuminate any small predictors – but, unfortunately, with only 319 patients, meaningful statistical significance on this data dredge is hard to come by. Worse still, the best predictor of treatment failure (or, really, lack thereof)? A peaked tympanogram (A and C curves) – you know, because we’re all routinely measuring tympanometry. Grossly bulging tympanic membranes were predictive of treatment failure, which has some face validity, at least – but, again, this is as compared between severe, moderate, and mild, which requires pneumatic otoscopy to differentiate.

The question here primarily concerns: can you take away good conclusions from bad data? The magnitude of the treatment effect seen in this trial far exceeded the treatment effect expected from antibiotics in other trials. And, consistent with that questionable generalizability, their findings reflect the stringent criteria determining their diagnosis of AOM. Then, they are relying upon their misguided definition for treatment failure, which relies on otoscopic signs, the same ones that will be colinear with worsened disease on initial examination. Unfortunately, the net result of all of this meandering is essentially no clinically useful insight. Considering the limitations the examination of the screaming ill toddler, more pragmatic approaches are necessary.

“Prognostic Factors for Treatment Failure in Acute Otitis Media”

http://pediatrics.aappublications.org/content/early/2017/08/04/peds.2017-0072

Let’s Get Together and Ignore PERC

The “Pulmonary Embolism Rule-Out Criteria” does not, as it implies, “rule out” PE.  It does, however, generally carve out a cohort for whom objective testing may be obviated, with the implication the costs and harms from false-positives and from anticoagulation outweigh the morbidity from missed PE. It is fairly well popularized and incorporated into guidelines for PE – and, well, at the least, physicians in an academic center, on the cutting edge of medical knowledge and education, should be applying appropriately.

Or not.

This is a prospective study enrolling undifferentiated Emergency Department patients with chest pain and shortness of breath. Research staff approached patients with these general chief complaints and collected the baseline variables needed for PERC, Wells, and other baseline clinical and historical data.  They collected data on 3,204 patients, 17.5% of whom were PERC-negative. Of these, 25.5% underwent some testing for pulmonary embolism – inclusive of D-dimer, CTPA, or V/Q scanning. Then, two – 0.4% – PERC-negative patients were ultimately diagnosed with a PE. The authors also present comparative data for the PERC-positive population, with the expected higher-frequency of testing and diagnosis associated with the absence of low-risk features.

PERC is, of course, an imperfect tool, an unavoidable consequence of any decision instrument narrowing a complex clinical decision down to a handful of variables. But, at the least, patients meeting PERC ought nearly all fall into the bucket of “why were you really considering PE in the first place?”, with few exceptions. For nearly a quarter of these to start down the rabbit hole of testing for PE is low-value and harmful medical practice at a population level, regardless of the potential magnitude of individual benefit for those true positives ultimately identified.

AOr, more concisely, this is nuts.

“Pulmonary Embolism Testing among Emergency Department Patients who are Pulmonary Embolism Rule-out Criteria Negative”

http://onlinelibrary.wiley.com/doi/10.1111/acem.13270/full

When Can You Clear the Intoxicated Cervical Spine?

The answer is: it depends – are we talking about the “real world”, or the world of evidence-based medicine?

This is a qualitative survey and prospective, multi-center observational study of the cervical spine clearance practices following major trauma. Performed at 17 centers, these authors collected data on definitions of evaluability, length of time in cervical-spine immobilization, and the diagnostic characteristics of CT in the context of the intoxicated trauma patient.

These authors analyzed 10,191 patients, approximately 3,000 of whom were intoxicated with alcohol, drugs, or both. The median injury severity score was ~10, with about a quarter of the cohort having “severe injury” or ISS >15. Incidence of any identified cervical spine injury was 7.6%, or overall 1.4% clinically significant CSI. In this intoxicated cohort, the sensitivity and specificity of the CT was 98% and 93%, respectively. A long questionnaire regarding real-world practice is presented, and the responses are very interesting – most surveyed indicated they would not clear the patient until they were clinically sober for a reliable examination, and patients stayed in their cervical collars for up to 8 hours as a result. On the other hand, despite their practice to the contrary, a small majority of respondents indicated they believed it was safe and reasonable to clear the cervical spine following a CT.

The takeaway for us in the Emergency Department, however, is that it is definitely safe to do so. Absent the multi-system trauma and mechanisms involved in this study, our typical otherwise-uninjured intoxicated patient has a vanishingly small chance of significant injury missed on CT. The risks and costs of staying in the collar – including those of follow-up MRI – exceed the potential harms of a missed injury. If these authors, in the Journal of Trauma – despite their spectrum bias – ultimately conclude it is safe to remove the c-collar based on the NPV in their sample, it is even moreso for our less severely-injured general ED population.

“Cervical spine evaluation and clearance in the intoxicated patient: a prospective western trauma association multi-institutional trial and survey”
https://www.ncbi.nlm.nih.gov/pubmed/28723840

Even the Best EHR Still Causes Pain

Paper is gone; there’s no going back. We’re all on electronic health record systems (cough, Epic) now, with all the corresponding frustrations and inefficiencies. Some have said, however, the blame lay not with the computer – but with the corporate giant whose leviathan was not designed to meet the needs of physicians in the Emergency Department, but rather support the larger hospital and primary-care enterprise. Unfortunately, as we see here, even a “custom” design doesn’t solve all the issues.

These authors report on their experience with their own homegrown system, eDoc, designed to replace their paper system, and built using feedback from health technology experts and their own emergency medicine clinicians. Their hypothesis, in this case, was that throughput would be maintained – ED length-of-stay as a proxy for operational efficiency. The interrupted time series analyses performed before-and-after the transition are rather messy, with various approaches and adjustments, including “coarsened exact matching”, but the outcome is consistent across all their models: the computer made things worse. The estimated difference per patient is small: about 6 additional minutes, but, as the authors note, in a mid-size ED handling about 165 patients a day, this adds 16 hours of additional boarding time – or the effect of shrinking your ED in size by up to 2/3rds of a room.

It is probably erroneous to simply blame “computers” as the culprit for our woes. Rather, it is the computer-as-vehicle for other onerous documentation requirements and regulatory flaming hoops. If the core function of the EHR were solely to meet the information and workflow needs of physicians, rather than the entire Christmas buffet of modern administrative and billing workflow, it is reasonable to expect a moderation in the level of suffering.

But, I think that ship has sailed.

“A Custom-Developed Emergency Department Provider Electronic Documentation System Reduces Operational Efficiency”

https://www.ncbi.nlm.nih.gov/pubmed/28712608