POTD: HIV Testing in the ED

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Hi everyone,

For my very last POTD, I wanted to talk about a topic requested by our very own Chair, Dr. Eitan Dickman. The question is: what HIV testing is performed in the ED, and how do we do it?

Types of HIV Antibody Testing

1) EIA (Enzyme ImmunoAssay): This is a very common form of HIV antibody testing, and is indeed the testing we do from the MMC ED. ELISA (Enzyme-Linked ImmunoSorbent Assay) testing might be a familiar name to some folks and is a type of EIA. These EIA tests are performed by taking a sample from the patient and combining it with synthetic or native HIV proteins. If there are any HIV antibodies within the patient sample, they will bind with the HIV proteins. Usually a second antibody - an enzyme-linked antibody, hence the name - is then introduced that binds to the HIV antibody to aid in detection. Thus, if the notorious HIV protein/patient HIV antibody/enzyme-linked antibody triplet is detected, then the antibody test is positive. 

However, it is vitally important to keep in mind that this initial EIA antibody test is only a screening test; a positive antibody screening test will automatically reflex to perform a confirmatory test. There are many types of confirmatory tests out there, but the lab advised me that we utilize RNA PCR testing. Which means, at MMC, you need to have a positive HIV antibody screening test + a positive HIV RNA PCR confirmatory test to be diagnosed with HIV. This is important to keep in mind when giving call backs to patients or following up on test results. 

2) Rapid HIV Test: This test can be very useful for point-of-care settings, as the results are available in 20-30 minutes. We do not at the moment have this option, but some other care settings do.

3) Western Blot Test: This was an option for confirmatory testing but has been largely replaced by newer technologies, like our PCR testing.

4) 4th Generation Test: This test is special in that it tests for both HIV antibodies and antigens. By testing for the antigen, called p24, HIV infection can be detected far earlier in the disease course than antibody testing, as antibodies can take up to 12 weeks to develop. This is critical in limiting HIV transmission, as the virus is far more likely to be spread early in the disease course while patients are asymptomatic and/or unaware they are HIV carriers. Our ED testing is not currently an antigen test, but it is good to keep in mind for future practice.

Accuracy in HIV Antibody Testing

The sensitivity and specificity of HIV antibody testing help determine the accuracy of diagnosing HIV in our ED. HIV antibody tests typically have a sensitivity of >99%, meaning very few individuals infected with HIV will be missed by our screening test. However, it is important to keep in mind that the "window period" of time between exposure to HIV and to when the antibody test can detect the infection; given that antibodies, again, can take up to 12 weeks to develop, if a new HIV carrier is tested during this time, there is the possibility of a false negative.

HIV antibody tests also typically have a specificity of >99%, meaning there are very few rates of false positives. Despite this, it is paramount that we also get the confirmatory RNA PCR test in addition to the screening antibody test in order to ensure diagnostic accuracy and limit any anxiety for patients.

Ordering HIV Testing in the ED

Testing for HIV in the ED is incredibly easy. When placing an order, navigate to the "ED Sexual Assault / STI / PID Order Set", click the "HIV-1/2 EIA, SCR W/ RFL", and voila! A specimen of blood, oral fluid, or urine is collected and sent to the lab. If the screening antibody test is positive, again, the confirmatory PCR will automatically be reflexed and sent. Any HIV result is automatically tracked by the ED tele doc, so no need to include it in ED Call Backs. So, really, just ordering it here will do most of the work.

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POTD: The Traumatic Eye Exam

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Hi everyone,

For today's POTD, I want to highlight a topic that still gives me the heebie jeebies when it arrives in our ED: trauma to the eye. Even if you get the most comprehensive history and have asked all the right questions, for a traumatic eye injury, it really comes down to...what's the physical exam? Your standard physical exam with a penlight, though important, can only get you so far, so you'll need a few extra tools in your tool belt to perform a complete assessment of these patients.

I'll walk through the 5 main additional tests to include in your eye trauma physical exam, the indications for each, where the supplies can be found in the MMC ED, and how to perform them.

1) Visual Acuity Testing

What's the indication? Any eye complaint, honestly. It seems so elementary, but it really is a core part of our eye exam.

Where is it at? The Snellen chart is often used in the ED to quickly assess and document visual acuity. A Snellen chart can be found hanging on the back wall in Fast Track for ambulatory patients that you can walk over. For those patients who are non-ambulatory or simply can't get out of the South Side stretcher tetris game that day, use a pocket Snellen chart (I bought one cheap on Amazon) or use a phone app (MDCalc saves the day, once again) so that you can test at bedside. 

How do I use it? I think most of us have used the Snellen chart, but here's a quick refresher. Have the patient stand a distance away from chart, with the distance usually indicated by the chart you're using. If you're at bedside and using a portable Snellen chart, a good way to approximate 4-6ft from the patient is to use the length of the stretcher. Cover one eye and test the lowest line they can read entirely correctly, cover the other eye and test the same, done. If your patient just completely fails the Snellen testing or can't participate in the exam, you can advance to Counting Fingers (CF) testing, then Hand Motion (HM) testing, then Light Perception (LP) testing and document your findings.

2) pH Testing

What's the indication? Exposures to chemicals/caustic agents. Aka weird liquid to the eye earns itself a pH strip.

Where is it at? This is the golden question. Sometimes there are dedicated ocular pH strips laying around either with charge, in Fast Track, or in peds. I personally couldn't find any on my hunt, so the solution is to use urine dipsticks, which can be found in peds. But order some anesthetic drops while you look.

How do I use it? First place 2 drops of anesthetic eye drops like tetracaine in your patient's eye, then wait about 5-10 mins so that your results aren't biased by the pH of the eye drops. While you're waiting and if you are using the urine dipsticks, cut the dipstick so that the pH box is the last box (seen below). Then tap the dipstick in the fornix of the eye, the little crevice between the lower eyelid and the eyeball. You can alternatively tap the dipstick to the eye directly, but be careful of the sharp edges where you cut the dipstick and make sure the eye is fully numb beforehand. Compare the pH color to the reference on the packaging; we are looking for a goal of pH 7.0. If you are anywhere off that, try irrigating with a morgan lens and sterile fluid and retest until you reach 7.0. Just know that urine dipstick pH range is only from 5-8.5.

3) Fluorescein Testing

What's the indication? Most any trauma to the cornea. Specifically evaluates for corneal abrasion, corneal perforation, corneal foreign body, epithelial keratitis, and HSV keratitis.

Where is it at? The strips for fluorescein stain testing are in the Fast Track cabinet labeled "Ophthalmology Supplies" on the far left. The Woods lamp can be found in the same cabinet in Fast Track or the doc box cabinet in peds. Order anesthetic drops while you search for the light.

How do I use it? Like the pH testing, first place 2 drops of anesthetic eye drops in your patient's eye. Drop a couple drops of a saline flush or additional anesthetic onto the fluorescein strip to saturate the strip, enough so that the liquid is about to drip off the orange end of the strip. Retract the lower eyelid and swipe the strip along the inner eyelid conjunctiva, not on the eye itself. Have the patient blink a few times to distribute the fluorescein across the whole eye, and then look with either cobalt blue light or UV light for any uptake of the fluorescein. Wherever you see uptake is where the cornea has been broken, as aqueous humor is exposed and has taken up the fluorescein dye. For the light, you can use the Woods lamp in Fast Track or peds, the Slit Lamp in Fast Track, or you can buy your own UV light pen on Amazon. Try to make sure not to get any fluorescein anywhere but the eye... it stains.

4) Slit Lamp Exam

What's the indication? Most any trauma to the eye, beyond even the cornea. Can be used as a light source for the fluorescein testing for corneal injuries and foreign bodies, but also evaluates for hyphema, anterior uveitis/traumatic iritis, and other non-traumatic anterior segment pathology.

Where is it? The slip lamp has permanent residence in Fast Track.

How do I use it? Get your patient seated with their chin in the chin holder and their forehead pressed forward into the forehead band. Turn down the lights in the examination room. Then set up your slip lamp, which is objectively tricky for first-time users as there's a lot of knobs and bulbs and buttons and screws. What I would focus on is putting one hand on the joystick at the base of the unit, which will change where the light beam is, and the other hand on one of the beam width knobs that juts out to either side near the middle of the unit, which will change how big your beam is. With your joystick, direct your light at an oblique 45 degree angle into the eye so as to not annoy your patient with direct bright light. And with your beam width knob, start with a wide light beam. Go slow and methodically through the exam, focusing on each layer (lids, conjunctiva, sclera, cornea, anterior chamber, iris, pupil, lens) and checking for pathology. Once you find pathology, then turn your beam width knob to make more of a thin slit (hence the name), which will provide a more detailed view of the pathology.

5) Tonopen Testing

What's the indication? Severe trauma to the eye, warranting concern for increased intraocular pressure. However, tonopen testing is contraindicated if there is concern for globe rupture, so be sure to first check for any signs suggestive of globe injury: eccentric pupil, extrusion of vitreous, obvious wound, seidel's sign, etc. Utilize the prior modalities (fluorescein testing, slit lamp testing) if you need better clarification of any globe injury.

Where is it? The tonopen is fiercely guarded in the South Side charge nurse filing cabinet in a blue case (seen below).

How do I use it? Patiently; ours is frustratingly finicky. But the lovely Dr. Kat Pattee provided amazing instructions in her own POTD on how to use it that I have followed myself and will share here. First, put a protective covering over the transducer. Calibrate the tonopen by holding the button down for 5 seconds, listen to 5 beeps, and then check that the display reads "dn" (meaning "down"). Proceed to turn the tonopen with the transducer pointed down toward the floor, hold steady for around 15 seconds, and wait until the display now reads "UP." Swiftly and smoothly flip the tonopen so that the transducer is pointing directly up at the ceiling, and the display should now read "pass." If the display instead reads "fail," try to calibrate all over again. Position the transducer perpendicular to the patient's pupil, press the button once, it will beep, and you should see displaced a series of dashes indicating it is ready. Very gently tap the cornea 10 times until it gives an average of the IOPs measured with each tap; the larger number is the IOP, the smaller number is the confidence interval. Repeat everything after the calibration steps at least 3 times and take the average of those numbers as your IOP. Do all this for the healthy eye first, and then repeat for the affected eye. Our goal for normal IOP is < 20.

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POTD: EtomiDate or EtomiHate?

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Hi everyone,

For a double dose of learning, today's extra POTD comes at the request of our wonderful PEM attending Dr. Hector Vazquez: should we be using etomidate in rapid sequence intubation (RSI) for septic pediatric patients?

Short answer? No. Long answer? It's complicated, but still no.

Etomidate's theorized effect on adrenal insufficiency = etomidate BAD

Etomidate is a bread-and-butter induction agent for us during intubation in the ED, often utilized for its hemodynamic stability and fast onset of action. However, the story started to really turn on etomidate in 2011 and 2012 when two systematic reviews and meta-analyses demonstrated that etomidate was associated with adrenal insufficiency and increased mortality in septic patients (Albert, Ariyan, & Rather, 2011; Chan, Mitchell, & Shorr, 2012). Why is this adrenal insufficiency thing such a big deal, anyways? It's because cortisol, our body's glucocorticoid that is produced by the adrenal gland, is absolutely vital during critical illness such as sepsis. Cortisol both helps maintain vascular responsiveness (good for blood pressure control in sepsis!) and has anti-inflammatory effects (good for fighting infection in sepsis!). The annoying part is that etomidate works through a cytochrome pathway that blocks conversion of cholesterol to cortisol. So more etomidate = less cortisol = adrenal insufficiency = not a good look.

Most of the adult literature on etomidate = etomidate EH BUT MOSTLY BAD

Honestly, like most of medicine, the data is controversial on the use of etomidate in sepsis in the adult literature. Even though the effect of etomidate on adrenal suppression is pretty well laid out, the question is if it is clinically significant and affects morbidity or mortality. A more recent systematic review and meta-analysis in 2021 reiterated the older meta-analyses findings, stating again an increase in adrenal suppression and mortality in septic patients (Albert & Sitaula, 2021). But, like most of medicine, many of the studies that were analyzed had some bias, some blinding blind spots, and varying definitions of all-cause mortality. A more recent RCT in 2023 even showed that there was no mortality difference between septic patients intubated with a single dose of etomidate vs. ketamine (Srivilaithon et al., 2023). All to say, the data isn't doing etomidate any favors when it comes to its use in septic adults, but it's not straight forward either. It's mostly bad, but we need better data, too. Journey with etomidate at your own risk.

Pediatric Sepsis Guidelines 2020 = etomidate BAD

Which brings us to peds patients. And make no mistake, the pediatric providers are stating it nice and clear for us: do not use etomidate in pediatric septic patients. In 2020, an expert panel released the holy grail for pediatric sepsis management, titled "Surviving Sepsis Campaign International Guidelines for the Management of Septic Shock and Sepsis- Associated Organ Dysfunction in Children." Included in these guidelines are 77 evidence-based statements made up of 6 strong recommendations, 52 weak recommendations, and 9 best-practice statements. 

And here's their recommendation regarding etomidate: We suggest not to use etomidate when intubating children with septic shock or other sepsis-associated organ dysfunction (weak recommendation, low quality of evidence). So no etomidate, but a weak recommendation... why do we even trust that? Well, pediatric patients just simply don't get the same research funding and consideration that adult patients get. A lot of the recommendations thus are based off of scant data, poor data, or adult data. And with such low quality of evidence overall, they only can claim to have weak recommendations. With regards to this recommendation in particular, as of 2020, no RCTs exist in critically ill children comparing etomidate to another sedation agent. But the recommendation is going off of two observational studies that included children in their patient population and four adult RCTs. Is it the cleanest recommendation? Definitely not. But they made an educated decision and pediatric septic patients should not be getting etomidate for RSI based on this recommendation. Maybe try ketamine instead.

So what were the 6 strong recommendations then?

  1. In children with septic shock, we recommend starting antimicrobial therapy as soon as possible, within 1 hour of recognition (strong recommendation, very low quality of evidence)

  2. We recommend removal of intravascular access devices that are confirmed to be the source of sepsis or septic shock after other vascular access has been established and depending on the pathogen and the risks/benefits of a surgical procedure (strong recommendation, low quality of evidence)

  3. In healthcare systems with no availability of intensive care and in the absence of hypotension, we recommend against bolus fluid administration while starting maintenance fluids (strong recommendation, high quality of evidence)

  4. We recommend against using starches in the acute resuscitation of children with septic shock or other sepsis-associated organ dysfunction (strong recommendation, moderate quality of evidence)

  5. We recommend against the routine use of inhaled nitrous oxide (iNO) in all children with sepsis-induced PARDS (strong recommendation, low quality of evidence)

  6. We recommend against insulin therapy to maintain glucose target at or below 140mg/dL (7.8 mmol/L) (strong recommendation, moderate quality of evidence)

To me, it wasn't so interesting to see what was included as strong recommendations, but more to see what was not included. If it's not listed here, but is typically something you would expect to be doing for a septic patient, it is likely listed as a weak recommendation or a best-practice statement. Meaning, lots of things we don't have all the evidence for but we have all collectively decided to do them anyway.

Happy intubating,

Kelsey

Resources:

1) https://pubmed.ncbi.nlm.nih.gov/21373823/

2) https://pubmed.ncbi.nlm.nih.gov/22971586/

3) https://jtd.amegroups.org/article/view/5542/5525#B19

4) https://pubmed.ncbi.nlm.nih.gov/32912050/

5) https://www.acepnow.com/article/should-you-etomidate-me/2/

6) https://www.nature.com/articles/s41598-023-33679-x

7) https://pubmed.ncbi.nlm.nih.gov/32032273/

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