Rotation 4: The Dose Makes the Poison

Posted by Emily at Friday, October 02, 2015

Despite the clinical nature of this rotation, my experience at the Michigan Poison Center certainly fit its “non-traditional” billing.  Full disclosure: I have been very interested in toxicology since shadowing at this poison center the summer after P1 year (and two more times as a P2), and thus this was the rotation I was most looking forward to.  It definitely lived up to my expectations and has solidified my plan to pursue a clinical toxicology fellowship following completion a PGY1 residency.  Please bear with me while I gush about this rotation.

As I mentioned, this rotation is considered non-traditional as it is geared towards emergency medicine medical residents (aka licensed physicians who have a few years of practice under their belts), although there were a handful of pharmacy residents and medical students on rotation as well.  In total, there were about 25 rotators, so you can imagine that we did not all physically visit and consult on every toxicology patient that passed through the Detroit Medical Center.  Instead, we were divided into four teams who were assigned one day a week to be “on-call”, with the following day designated for team “call backs”.  Additionally, each team was assigned one weekend to be on-call.  This was confusing to me initially because I’m used to traditional rounding which generally occurs at the same time every day with more or less the same group of people.  Consult services, like toxicology, are more flexible and can see patients at any time, day or night.  A typical day at the poison control center looked something like this:

0730-0900 – consults or call backs

On the days my team was on-call, our designated team leader would call the poison center at 0600 to see if there were any patients within the Detroit Medical Center network of hospitals who required a toxicology consultation.  Some days there weren’t any patients, other days there were one or two.  It was up to the team to decide who would see the patient.  I consulted every patient that was available to me to consult, though I always teamed up with the physicians in my group who performed a physical exam, asked follow-up questions of the patient and the patient’s nurses to gain a more complete toxicologic history, and wrote consultation notes for the medical record.

On call-back days, we were required to log into the Toxicall system which is the database that tracks all of the calls that come in through the poison center hotline each day.  From here we returned calls to health care providers who may have consulted the poison center the night before for recommendations regarding a toxic exposure.  As rotators, it was our job to gather as much pertinent information as possible about the patient’s history, as well as their treatment course and most recent labs and vitals.  From there we would consult with the toxicology fellow or attending toxicologists about what additional recommendations for care needed to be made, and then write a SOAP note to log our encounter and recommendations in Toxicall.

0900-1100 – case review

Each morning, the on-call and call back teams would present the cases they had seen.  These were case presentations with a twist, however.  Whenever possible, the toxic substance was withheld so that we could try to guess what it was based on the patient’s presentation, vital signs, and lab findings.  Certain classes of medications have specific toxidromes that can help clinicians narrow down the possible ingestant(s).  For example, sympathomimetics (like bath salts, amphetamines, and cocaine) cause increased blood pressure, heart rate, respiratory rate, and temperature, pupil dilation, CNS activation, sweating, and GI activation like nausea, vomiting, and diarrhea.  Conversely, sedative-hypnotics and opioids cause decreased blood pressure, heart rate, respiratory rate, and CNS depression.  Patients rarely present with a textbook perfect toxidrome, especially if they ingested more than one substance (or even if they’re withdrawing from one substance while overdosing on another).  Toxicology requires a lot of problem-solving and detective work, which made cases my favorite part of the day.  It was just piecing together puzzles all morning!

Of course, it was frustrating when the poison was never elucidated because the patient was intubated and unable to tell us what they took.  I was surprised at how often it didn’t matter what the actual toxic ingestion was.  The toxicologists made treatment recommendations based on the patient’s symptoms, not necessarily based on what the patient claimed to have taken.

Here are some examples of the many and varied toxic ingestions I saw during this rotation: synthetic cannabinoids, lithium, heroin, glipizide, bupropion, acetaminophen, Coricidin, Listerine, antifreeze, quetiapine and cocaine, Dust-Off, a caterpillar, and some chemical called 3FPM that the patient ordered online.  We were also consulted about a Massasauga rattlesnake bite!

1100-1200 – lunch

1200-1400 – lectures, journal club, topic presentations, field trips

The afternoons were devoted to lectures on a wide variety of toxicology topics which were given by the handful of toxicologist attendings who worked at the poison center.  We reviewed everything from acid-base chemistry and acetaminophen toxicity to poisonous mushrooms and venomous spiders.  Each rotator was also required to present a journal club and a topic presentation.  My presentations were on colchicine toxicity and castor bean/ricin poisoning.

We had two field trips during the rotation: one to the Detroit Zoo to learn about venomous snakes, and one to the Michigan State University botanical gardens to learn about poisonous plants.

castor beans from the botanical gardens

autumn crocus, the plant from which colchicine is derived, at the botanical gardens

1400-1600 – review materials, work on projects from home

My major assignment for the rotation was to help develop a protocol for the management of zinc/aluminum phosphide poisoning.  Aluminum phosphide is a rodenticide that’s especially prevalent in agriculture southern Asian nations like India, but can easily be obtained in the US via the internet.  When aluminum phosphide comes in contact with water, it releases phosphine gas which is super toxic because it disrupts mitochondrial function.  When ingested, stomach acid causes an even greater release of phosphine gas.  Not surprisingly, the mortality rate from aluminum phosphide ingestion is very high, and unfortunately there isn’t an antidote.  In addition to being incredibly toxic to the individual who ingested the aluminum phosphide, the patient can off-gas phosphine even post-mortem which puts the healthcare providers caring for these patients at risk.  These patients essentially become HAZMAT problems.  It’s a pretty fascinating issue.  Here’s a link to a news article about a recent case of aluminum phosphide ingestion in New Mexico: http://www.koat.com/news/man-overdoses-vomit-contaminates-taos-hospital/34890148

And now, dear readers, please allow me to list the reasons why I love toxicology and thus loved this rotation:

• Toxicology is a broad specialty because the dose makes the poison, which means that basically anything can be toxic in the right quantities.  This means toxicologists have to be well versed in pharmacology and biochemistry, because toxic ingestions can be household items just as easily as they can be medication related.
• Toxicology is all about SOLVING PUZZLES.  I love this so much.
• Toxic ingestions often have a social component to them that I find very interesting.  For example, lead poisoning is more prevalent in low-income areas because the houses are often older and thus more likely to have been painted with lead paint.  Or parents may be reluctant to admit that their child could have accessed their prescription (or not prescription) medications out of fear that Child Protective Services will be contacted.  These complicated situations add a whole new layer of challenge to the field.
• I am a biologist at heart, and toxicology caters to this because beyond drugs, toxicologists are concerned with poisonous plants and animals too!
• In my opinion, toxicology offers pharmacist a good balance of activities including clinical care, drug information, research, teaching, and administrative duties. 
• Toxicology offers tons of variety because there are always new poisons (see: Tide Pods) and drugs of abuse trends are always changing.  There is always something new to learn.
• Finally, I really love emergency medicine docs.  All of the toxicologists and EM residents who I worked with this month had the most delightfully dry senses of humor on top of being super smart.  It made me excited to come in to rotation every day. 

Long story long, this non-traditional rotation in poison control definitely met my expectations!  I have been working on narrowing down residency options based on what programs also offer toxicology fellowships or at the very least are associated with poison centers and have PGY1 rotations in toxicology.