Tuesday, June 7, 2016

Diphenhydra-what? - The Continuous Benadryl Infusion

Mast Cell Disease encompasses numerous conditions that impact the functioning and/or production of mast cells. To provide a brief synopsis, mast cells are a type of immune cell. They play a significant role "in defense against pathogens." [ x ] The mast cells release chemicals called mediators when triggered. The mediators cause a host of symptoms. Quite a few, but not all, are allergic in nature.

For example, consider a mosquito bite. The red, welted bump that forms is a histamine reaction. Histamine is one of the hundreds of chemicals called mediators that mast cells release. Surely you have encountered a person carrying an Epi Pen at one point in your life. You know, the yellow auto injector jammed into the thigh to relieve throat closing and other harmful symptoms caused from contact with an allergen? That life threatening allergic reaction is anaphylaxis. 
A Mast Cell Disease patient may have too many mast cells, or their cells function improperly, releasing the chemical mediators at inappropriate times. Any symptoms are a result of the mast cells being easily triggered. The chemical release can even occur without a trigger, simply just because. This differs from the IgE mediated allergy example above. Since Mast Cell Disease is a cellular problem, triggers are inconsistent. Allergic symptoms arise without the presence of a "true" allergy.

During allergy season, drugstores stock their shelves with medications like Zyrtec, Claritin, and Benadryl. Those are H1 blockers. They block the symptoms from the histamine released by mast cells. That same class of medication is used in combination with other drugs for the treatment of Mast Cell Disease.

There are cases of Mast Cell Disease where traditional over the counter treatments are not fully effective. These patients live in a near constant anaphylactic state. Doses of oral Benadryl from Walgreens do not lessen the severity of the reactions enough. Part of the problem is that there are 200+ chemicals released from mast cells, but current medications only block a few of them. The situation can quickly become life threatening. Unfortunately, I am one of those severely afflicted patients.

In situations like mine, a treatment often turned to as a last resort is known as an intravenous Continuous Diphenhydramine Infusion, sometimes referred to as the CDI. What is Diphenhydramine, you ask? It is simply a fancy term for Benadryl. The CDI receives such a name because it is literally a continuous infusion of Benadryl. Yes, there is Benadryl coursing through my veins every second of every day. The concept tends to perplex people. It scares them! I was initially terrified myself, and had a multitude of questions. Many were similar to the questions and concerns frequently asked by others.

The Continuous Diphenhydramine Infusion study is posted in The Blood Journal by Dr. Lawrence Afrin.

"What is it?"

Like previously stated, the CDI is a 24 hour continuous infusion of intravenous Diphenhydramine (Benadryl). It is administered via pump through a central line.

"So, how does it work?"

On a weekly basis, a home health company delivers all of my infusion and enteral (feeding tube) supplies. The CDI is included in that delivery. The Benadryl for my CDI does not come to me in vials because it must be diluted. Instead, it is in bags. The amount necessary for the 24 hour infusion is drawn out of the vials and injected into saline under a sterile hood by the pharmacist affiliated with a home health company. I receive enough bags to last an entire week.  They are switched out daily. The ones not currently in use are stored in the refrigerator to ensure stability.

I hook up one CDI bag to my hickman central line every 24 hours. Inside of the CDI bag is the intravenous 350 mg of Diphenhydramine (Benadryl) and 700 mL of NS saline. During the 24 hour span, I usually receive 300 mg of medication. That calculates to 12.5 mg of Benadryl slowly pumped over an hour, every hour.

I connect each bag to a portable IV pump also provided by the home health company. The pump is set and locked by the company at the doctor prescribed dose. This ensures patients cannot accidentally harm themselves with too much or too little medication. The same pump is used each day, clearing the volume before starting the new bag. There is a bolus button or emergencies, which accounts for the overfill.

"How is the continuous pump different than bolus doses of Diphenhydramine (Benadryl)?"& "Is it safe to have THAT much Diphenhydramine (Benadryl)?"

Bolus doses of Diphenhydramine (Benadryl) are different than the CDI in both administration and the potential resolution of symptoms. Normally, Diphenhydramine (Benadryl) is given in as needed doses or 25 to 50 mg every 4 to 6 hours as instructed. Medical lingo terms this as a bolus.

Patients with Mast Cell Disease encounter a problem when the need for Diphenhydramine (Benadryl) becomes more frequent than the medication is safely advised to take. They must resort to taking Diphenhydramine (Benadryl) when reaction symptoms resurface. Depending on disease progression, it may be well before the 4 to 6 hour is up.

Because of Diphenhydramine (Benadryl)'s half life, administering small amounts of the medication constantly in the form of the CDI is more effective. It suppresses the huge, life threatening rebound reactions that sometimes occur with the typical administration. It also prevents a patient from taking excessive amounts of medication to stop a reaction. 
For example: Before the CDI, I could take 50 mg of Benadryl, 20 mg IV pepcid, 50 mg IV steroid, and require an EpiPen less than an hour later. If triggered again, the amount of medication previously taken is irrelevant. Another dose is needed to stop the attack. 

However, I now take less Diphenhydramine (Benadryl) on the CDI than when following the typical administration of 25 to 50 mg doses per 4 to 6 hours. 

The idea of the pump is to prevent the severely afflicted patients, who have failed to achieve stability with oral medications and then bolus IV doses, from using large and unsafe amounts of Diphenhydramine (Benadryl). 

"Aren't you tired and drugged all of the time?"

This is the question I hear the most! I experience less side effects from the pump than when taking bolus doses of Benadryl in normal administration. The only occasions I notice side effects, like drowsiness, is when I receive "emergency" dosing along with my regular continuous dose.

"What symptoms does it prevent?"

The symptoms that it does well at controlling have unless in a flare are: itching, flushing, cardiac symptoms, nausea, neurological symptoms (flashing lights in vision, tremors), urinary tract involvement, etc. The pump does a good job at decreasing the severity of symptoms rather than completely preventing them.

Overall, the CDI has kept me alive. I am certain I would not typing this post today without it. It is the only treatment counteracting the severe reactions, as I was anaphylaxing to almost all nutrition. Because of it I am stable in the sense that I am not going into full blown reactions every half hour for no reason whatsoever.

"How long were you on the CDI before noticing an improvement?"

Symptoms improved within hours of starting the CDI. While I did not immediately become functional, it quickly "put a band-aid" on a life threatening situation by stopping the severe cycle of reactions. 

"What symptoms remain?"

On a daily basis, I still deal with major symptoms. I cannot eat orally without severe reactions, despite the pump. I manage to hold my own on elemental formula delivered into the small intestine via J tube. The reactions from being fed in my small intestine instead of the stomach are less intense. Specialists say that it is the difference in reactivity between the mast cells in my stomach versus small bowel. Who knows? Nonetheless, the formula causes issues of its own.

While running I typically experience: tremors, tachycardia, flushing, rashes, colitis, burning pain in organs, intermittent swelling in face, joints, and throat, pancreatic involvement, and dystonia. To reiterate what I previously said, the CDI does not rid of symptoms completely, it only decreases them. The severity is milder than they are without the pump. The majority of the patients on the CDI remain quite symptomatic. Although histamine is a major contributor to symptoms, mast cells still release a plethora of other chemicals that the CDI does not treat, making other medications necessary.

"How do you carry the pump around 24/7?" 

No, being on the CDI does not mean staying tethered to an IV pole. The CDI bag and pump is portable. It is small and light enough to fit in a backpack. The video provides a demonstration. In the video, the larger bag in the backpack is the Benadryl. Beside the Benadryl is Pepcid, which I run continuous as well. IV fluids are on the third pump. The tiny blue pump is for my tube feeding formula.
The backpack in the video is the Very Bradley Backpack Babybag. It is my #1 recommendation for those connected to multiple pumps. The inside is washable, contains pockets to hold the pumps, and comes with an easily sterilized surface. Yes, the easily sterilized surface I am referring to is intended by the manufacturer for changing baby diapers, but shhh do not tell anyone!

A fancy backpack is not necessary. Any can really be used. Pictured below is a Target backpack, modified with hooks. As you can see, I kind of just through the pumps in there. Hanging the CDI bag is not imperative because the air is primed out of the bags at the pharmacy.

Never in a million years did I imagine I would end up on a last resort type of treatment, where the long timer effects remain unknown, and still in the process of being studied. I am extremely grateful that the CDI is an option for me, while Mast Cell Disease patients like me wait for science to catch up! Hopefully this helps the genuinely curious or anyone enduring a similar medical situation.

Did you like this post? Read 150,000+ mg of Benadryl: Continuous Diphenhydramine Infusion Update