Biphasic anaphylaxis

I have written about anaphylaxis before (in the form of a video) and also shared a Why We Do What We Do on Epinephrine. Perhaps appropriately so, here is a “delayed” post on biphasic reactions, which the actual occurrence of, or the potential for lead to further ED observation and admissions for children with anaphylaxis.

Generally, a biphasic reaction means that there has been an asymptomatic period of ≥1 hour with a subsequent resumption of symptoms without further antigen exposure. Though it is hard to precisely estimate the incidence Stark followed a group of 25 patients prospectively and Ellis followed 103, both noting rates of about 20%. A larger retrospective review from Alqurashi noted a rate of 14.7%. These were ED based. However, children receiving oral food challenges according to Järvinen in J Allergy Clin Immunol and Lee in Allergy Asthma Proc saw rates much lower (1.5-2%). So the bottom line is that we don’t really know.

In general the second phase is usually less severe than the first. Urticaria is more common, and is many times the only symptom per Ellis. As is the case with many understudied phenomena there are case reports of fatalities as well. Recurrent symptoms generally appear in the first 4-6 hours, but can occur out to 72 hours. However, most will be within 24-30 hours.

With regard to specific risk factors for biphasic reactions in children I wanted to highlight one study that reviewed nearly 500 patients with anaphylaxis  the aforementioned retrospective review from Alqurashi. Overall in their database from two Canadian Pediatric Emergency Departments 71/484 (14.7%) visits developed biphasic reactions. It is interesting that 49/71 (69%) had respiratory and/or cardiovascular manifestations (different than Ellis) and 35/71 (49%) got epinephrine. Alqurashi also identified five independent predictors for biphasic reactions, and if you take anything home from this post I want this to be it:

  • Age 6 to 9 years – OR 3.60 (95% CI 1.5-8.58)
  • Delay in presentation to the ED >90 min after the onset of the initial reaction – OR 2.58 (95% CI 1.47-4.53)
  • Wide pulse pressure at triage – OR 2.92 (95% CI 1.69-5.04)
  • Treatment of the initial reaction with >1 dose of epi – OR 2.7 (95% CI 1.12-6.55)
  • Treated with inhaled β-agonists in the ED – OR 2.39 (95% CI 1.24-4.62)

What should you do with this info? Well, asymptomatic children at 4 to 6 hours can be discharged home. Any child that has developed biphasic reaction or is still symptomatic should not go home. I would strongly consider admitted/observing children with the above five predictors as well.


Alqurashi W, Stiell I, Chan K, Neto G, Alsadoon A, Wells G. Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis. Ann Allergy Asthma Immunol. 2015 Sep;115(3):217-223

Ellis AK, Day JH. Incidence and characteristics of biphasic anaphylaxis: a prospective evaluation of 103 patients. Ann Allergy Asthma Immunol 2007; 98:64.

Järvinen KM, Amalanayagam S, Shreffler WG, et al. Epinephrine treatment is infrequent and biphasic reactions are rare in food-induced reactions during oral food challenges in children. J Allergy Clin Immunol 2009; 124:1267.

Lee J, Garrett JP, Brown-Whitehorn T, Spergel JM. Biphasic reactions in children undergoing oral food challenges. Allergy Asthma Proc 2013; 34:220.

Stark BJ, Sullivan TJ. Biphasic and protracted anaphylaxis. J Allergy Clin Immunol 1986; 78:76.


Tiny Tip: BISAP for Pancreatitis

EDITOR’S NOTE: I often struggle with determining whether the presentation is pancreatitis or whether it’s PANCREATITIS. There are a number of scoring systems to help evaluate this question but one in particular is nicely suited to the Emergency Department. I like Doran’s Tiny Tip that can help you remember some of the key features to consider. – EP The severity and sequelae of acute pancreatitis ranges wildly, from mild epigastric pain with a benign natural history ...

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Doran Drew

Doran Drew

The post Tiny Tip: BISAP for Pancreatitis appeared first on CanadiEM and was written by Doran Drew.

Did the Affordable Care Act actually reduce ED visits as politicians promised?


The Affordable Care Act (ACA) was supposed to expand coverage to the uninsured and many politicians claimed this would result in lower use of “expensive emergency rooms” for the treatment of patients’ acute complaints. Ignore, for the moment, the controversy about whether or not the emergency department (ED) is an expensive or appropriate place for patients to seek care. A new survey [PDF] from the Center for Disease Control and Prevention (CDC), asked the question: Did the ACA actually reduce ED visits as politicians promised [1]?


This presumption, that increased health insurance coverage would decrease ED visits, runs counter to 2 facts.

  1. Only one-fifth of patients visit the ED due to problems such as their doctor’s office being closed or lack of other providers. The vast majority goes to the ED because they (or any other prudent layperson) think they are having an actual emergency.
  2. recent randomized experiment demonstrated that giving Medicaid to the uninsured in Oregon led to a 40% increase in ED visits [2].

The CDC study did not answer the question about ED visit reduction

The authors used the National Health Interview Survey to assess patterns of ED use among adults age 18-64 in 2013 and 2014 — the years straddling the ACA’s major insurance expansions [1].

Figure 1 ACA - no label

Fig 1. Adults (age 18-64) with ≥1 visit to the ED in the past year, by number of visits, health insurance coverage status, and year: United States (2013 and 2014). Figure from [1].

In this study based on patient recollection, the percentage of people reporting an ED visit during the previous 12 months did not significantly differ between 2013 and 2014. This is true for both the Medicaid and privately insured subgroups. We know that about 10 million people gained insurance coverage due to the ACA’s expansion of Medicaid and through private health insurance marketplaces in 2014. How is it that none of those people ventured their way into an ED?

Contrast these findings to the highly cited Oregon Medicaid experiment clearly demonstrated that the absolute number of total ED visits went up by about 40% during its Medicaid expansion at 18 months [2]. This Oregon study also showed that the percent of patients with any visit, which is the same measure reported by CDC, also significantly increased by about 20%.

So why are the CDC and Oregon studies not in agreement?

Like any other scientific paper, the devil is in the details, or in academic-speak, the methods. The Oregon study results differ from the CDC study in that the former used an administrative database and the latter used patient self-report. A true comparison would require comparing the CDC data to self-reported ED visits. Fortunately, the Oregon researchers provided us that information as well (Figure 2). The in-person interview at 12 months showed no significant difference for patients getting Medicaid on ED visits.



Figure 2 ACA copy

Fig 2. Comparing ED visit results from administrative data and self-reports. Table from [2]

So ultimately in the end, both the Oregon and the CDC study – looking at a 12 month period – found that patients did not report any significant change in the likelihood of visiting an ED [1,2]. So where did this 40% increase in ED visits in Oregon come from? If you look at Figure 2, the administrative ED data at 18 months clearly show significant increases in percentage of patients with any ED visit and the total number of ED visits.

So maybe it’s true that Obamacare nationally hasn’t changed the overall number or likelihood of visiting the ED – which runs contrary to our predictions – but that might just be the results of the sampling method (self-report vs. administrative database) or too short an observation period (12 vs 18 months).

I would be willing to bet that when researchers look at the real numbers of how many patients actually went to the ED, not just what interviewees say they did (which is subject to recall bias), our predictions of a spike in ED visits will be corroborated.

Bottom line

To honestly answer the question – Did the ACA actually reduce ED visits as politicians promised? This CDC study did not clearly answer the question. What we need is a true analysis of the administrative records, free from recall bias.



  1. Gindi RM, Black LI, Cohen RA. Reasons for Emergency Room Use Among U.S. Adults Aged 18-64: National Health Interview Survey, 2013 and 2014. Natl Health Stat Report. 2016; (90):1-16. PMID: 26905514
  2. Taubman SL, Allen HL, Wright BJ, Baicker K, Finkelstein AN. Medicaid increases emergency-department use: evidence from Oregon’s Health Insurance Experiment. Science. 2014; 343(6168):263-8. PMID: 24385603

Author information

Cedric Dark, MD MPH

Cedric Dark, MD MPH

Assistant Professor of Medicine
Section of Emergency Medicine
Baylor College of Medicine;
Founder & Executive Editor,
Policy Prescriptions ® (

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We are all sepsis, by Alberto Del Castillo

We are living an increase in the incidence of Sepsis in recent years probably due to the increase of the population survival and the use of new immunosuppressive treatments.

This increase in incidence has not been come with the development of new therapies as we see in other illnesses. So, our efforts are now aimed primarily at early detection with an immediate start of the available therapies. For these reasons we can consider Sepsis a time dependent pathology, and the creation of a
Sepsis Code similar to pathologies such as the acute myocardial infarction or stroke is fundamental.

The creation of a
Sepsis Code must not make us forget the long road that many patients with Sepsis run through and their sequels, with also the family suffering. That´s why so important to detect a patient with sepsis as detecting and treating post ICU syndrome. Probably in the future we will see the birth of a Post-ICU síndrome Code.

Meanwhile, the next April 28th and 29th is going to be held the
Second Multidisciplinary Meeting on Sepsis at the Hospital Clínico Universitario San Carlos in Madrid. An international meeting as you can see in the program where we all fit.

We hope that you could attend, because we are all Sepsis.

Dr. Alberto Del Castillo
Multidisciplinar Sepsis Unit
ICU of
Hospital Son Llàtzer, Palma de Mallorca