Health Topics – Johns Hopkins Medicine Podcasts

Just how inaccurate are the devices used to measure oxygen in the blood, called pulse oximeters, in people with darker skin? That’s the question that Ashraf Fawzy, a critical care medicine expert at Johns Hopkins, and colleagues addressed in a recent study.
Fawzy: There is a gradation of how inaccurate the pulse oximeter is based on the skin pigmentation. We measured skin pigmentation using a colorimeter, a handheld device that measures the light reflectance off of the skin and that correlated with melanin levels. And we showed that those with darker skin pigmentation that is objectively measured has worse accuracy of pulse oximeters. We had a pretty small sample and this needs to be done in much broader samples.   :29
Fawzy says pulse oximeters were developed decades ago and really haven’t changed much at all over the years. The problem of inaccuracy in those with darker skin was very apparent during the pandemic, and now points clearly to the need to update the technology, which is vital for many hospitalized people. At Johns Hopkins, I’m Elizabeth Tracey.

Pulse oximeters are essential to measure someone’s level of oxygen in their blood, yet they haven’t been updated since the 1970s and they’re not well regulated by the FDA. That’s according to Ashraf Fawzy, a critical care medicine expert at Johns Hopkins, whose research has shown that in people with darker skin tones inaccuracy abounds.
Fawzy: We're seeing that this problem is happening in the clinical setting. These devices are used in the clinical setting but they're being tested in healthy participants on labs. We need more testing and more regulatory guidance about how we should be approaching that testing in a clinical setting, whether it's pre market or whether it's post market it probably needs to these devices need to be shown that they work in the setting that they're going to be used.    :26
Fawzy notes that device regulation is complex and may not require new clinical trials to demonstrate efficacy or safety. He says clinical testing of current pulse oximeters would help define their limitations. At Johns Hopkins, I’m Elizabeth Tracey.

If you’re a person with darker skin, a device to measure oxygen in your blood called a pulse oximeter may be inaccurate, sometimes extremely so, accumulating research shows. Ashraf Fawzy, a critical care medicine expert at Johns Hopkins and one author of a study examining these devices, says while we are waiting for a technology fix, another avenue should be pursued. 
Fawzy: In the meantime there can be advances in the way that they're regulated right now. The way that they're regulated they only have to be tested, at least the ones that we use in a medical setting, have to be tested in at least 10 healthy participants in a laboratory setting with at least 200 pulse oximeter measurements with arterial blood gas measurements. And they only suggest that 15% of the sample or at least two participants are darkly pigmented and don't define that.   :29
Fawry notes that the FDA has taken one step in improving regulation and looks forward to more soon. At Johns Hopkins, I’m Elizabeth Tracey.

Pulse oximeters are devices used to measure how much oxygen is in someone’s blood, and they are critical in settings like ICUs. Yet research shows that in people of darker skin tones they can be wildly inaccurate. Ashraf Fawry, a critical care medicine expert at Johns Hopkins, says these devices are sadly in need of an update.
Fawzy: Think about every other technology we've had. I'm sure you don't use anything that was created in the 70s and hasn't been updated. We need a technological fix here. The way that we use pulse oximeters is not going to change, we need these devices in the clinic, we need them in the hospital, we need them to tell us how patients are doing second to second, but we need them to be more accurate. The way that they work hasn't changed in five decades essentially.  :30
Fawzy says his own experience with patients in the ICU has shown that harm is possible if oxygen levels aren’t in range, and pulse oximeters are needed for this purpose. At Johns Hopkins, I’m Elizabeth Tracey.

An injectable drug called omalizumab now may be used to manage severe food allergies, the FDA has decided. Robert Wood, an allergy expert at Johns Hopkins, says the drug will only work if people are taking it.
Wood: This is a therapy that will only work while you're on it. It's like our antihistamine that works while you're on it and then once you stop it it wears off, but is by no means automatically lifelong. If you want lifelong protection it's a lifelong therapy, for the family that is particularly worried about the preschool years they could use it for the preschool years and then stop it when they think their child is old enough and aware enough of their food allergy that they can practice avoidance more successfully. I actually see it rarely being used lifelong, very commonly used for these higher risk periods in people's lives.  :32
Wood says almost everyone tolerates the therapy just fine, even very young children. He’s excited to be able to offer something besides food avoidance and epinephrine in case of a reaction. At Johns Hopkins, I’m Elizabeth Tracey.

Omalizumab is an injectable drug just approved by the FDA to treat severe food allergies. Robert Wood, one author of a study used to inform the agency’s decision and an allergy expert at Johns Hopkins, says risks discerned in the study were very small, even for the youngest participants.
Wood: The other question that we discussed with our patients is what are the risks of the treatment? One of the advantages we had doing this study was that because it's an old drug there was lots of experience and knowledge about risk and they turn out to be very, very small. This drug had never been studied in anyone age 5 or under before this study and we did not see any signals for higher risk in young kids. The only warning that is on the package right now is that somewhere around one in 500 to 1000 people will have an allergic reaction to the injection itself.   :31
 Wood notes that the risk of a very severe allergic reaction to a food can include death, so for those with such allergies this can be a lifesaver. At Johns Hopkins, I’m Elizabeth Tracey.

Consequences of food allergies can be life-threatening, which is why FDA approval of omalizumab to treat them is welcome. Robert Wood, one author of a study used to inform the agency’s decision and an allergy expert at Johns Hopkins, says it’s not your imagination: food allergies are more common than they used to be.
Wood: Estimated prevalence for children it's somewhere around 8% of all kids have true food allergy. That is probably twice as high as it was 30 years ago, I'd say probably because it's hard to compare studies head-to-head, but the estimates are somewhere at least 17,000,000 Americans it's actually a little more common in adults than it is in children so we talk about you know one out of every six children in any grade school classroom have true food allergy.   :26
Wood says before this drug was approved avoidance of the foods one was allergic to was the primary means to reduce risk, and those with such allergies were advised to always carry epinephrine in case of an allergic reaction. At Johns Hopkins, I’m Elizabeth Tracey.

Feeding very young children peanut products can assure that they don’t develop an allergy to peanut. Can this strategy be expanded to allergies to foods like milk, meat, or egg? Johns Hopkins allergy expert Robert Wood comments.
Wood:  There’s an enormous market that's grown around this early introduction idea, so yes, you can buy lots of products that contain the major allergens in a form that babies can eat them. The same that's been shown for peanut is pretty clear for other allergens that early introduction could be protective. On the other hand even though the guidelines for preventing peanut allergy are now 8 years old there's been absolutely no reduction in peanut allergy. Implementing this information out into practice has not occurred.  :29
Wood says while it isn’t known precisely why the guidelines for feeding peanut have not reduced prevalence of this allergy, many believe it’s because parents don’t feed enough peanut over a long enough period of time to desensitize kids. At Johns Hopkins, I’m Elizabeth Tracey.

Can food allergies be outgrown? Elizabeth Tracey reports
Most people know about peanut allergy, since it impacts a lot of people, especially children. Can these allergies be outgrown? Robert Wood, an allergy expert at Johns Hopkins, says for most, that’s wishful thinking.
Wood: That includes everyone with peanut allergy, everyone with tree nut allergies. The odds are 80 to 90% that they will not. The odds are 70-80% they will outgrow something like a milk or egg allergy but the 20 or 30% who don't persist all the way into adulthood with these very severe allergies for foods that are hard to avoid. We've done lots of studies on the natural history of these allergies and have some pretty good markers of likelihood of being outgrown or not.    :26
Wood is one author of a recent study demonstrating the efficacy of omalizumab, an injectable drug used for asthma, in controlling food allergies in the majority of people in the study, including children younger than five years of age. The drug controls food allergies broadly but also seasonal allergies and asthma for most. At Johns Hopkins, I’m Elizabeth Tracey.