The Dirty Epi Drip and IV Flow Rates

Jun 02, 22
The Dirty Epi Drip and IV Flow Rates

Recently, I put out a video on the dirty epi drip (YouTube and TikTok) and in that video I discuss the use of this modality when in a pinch (i.e. can’t get push-dose pressors and/or a pump is not available as a patient is crashing).  To be clear and explicit, I would prefer vasoactive medications be given as push-dose or via a pump, as both of these are a much better way to be precise and safe in terms of how much medication you are actually giving a patient.

In the video I quoted a paper [1] which stated that “wide open” flow rate through an 18g IV was 20 – 30cc/min.  Two different people reached out to me concerned that there is another paper [2] that quotes a “wide open” flow rate through an 18g IV as being 98.1cc/min.  The concern was that if flow rate is higher, we would be giving a much higher dose of epinephrine per minute which could have some potential untoward outcomes.

The Dirty Epi Drip:

  • 1mg of epinephrine placed into a 1L saline bag and run through an IV
  • This is not perfect, but buys time until a pump or push dose epinephrine can be made
  • It is called dirty epi drip for the simple reason that it is mixed at the bedside as opposed to getting it from the pharmacy
    • In addition, it is not precise, and you don’t have an exact idea of how much medication you are giving
    • Again, a more precise method would be through a pump or as push-dose
  • Infusion rates will be dependent on height of the fluid bag above the patient, the size of the IV catheter, pressure placed on the IV bag, and micro- vs macro-drip set
  • If needing this, I highly recommend using it with a micro drip setup

Micro vs Macro Drip Setup

  • Both macro and micro drip setups connect the IV bag to a drip chamber
  • Macro and micro drip refer to the diameter of the needle where the drop enters the drip chamber

Image From Mometrix (Link is HERE)

  • This is then connected to the IV tubing which can either attach to an IV catheter directly or to a connecter attached to the IV catheter

  • Macro-drip tubing delivers 10 to 20gtts/mL whereas micro-drip tubing delivers 60gtts/mL
  • To calculate the drops per minute, the formula is total volume (mL) divided by time (min) multiplied by the drop factor (gtts/mL) which equals the IV flow rate in gtts/min

What IV Packaging Say for IV Flow Rates

Paper #1: Pierce et al (The one I quoted – Micro Drip Setup) [1]:

  • Gravity-driven micro drip infusion sets are designed such that the number of drops per minute equals the milliliters/hr (i.e. A drip rate of 60drops/min delivers 60mL/hr)
  • When the flow rate increases to the point that a continuous column of fluid replaces discrete drops in the chamber (“Wide-open”) it is no longer possible to visually quantify flow rate

Image from [1]

  • In the “wide-open” state the rate of medication/volume delivery will vary depending on two factors:
    • Height of the infusate bag relative to the patient
    • IV catheter size
  • What They Did: Used a micro-drip infusion set, plugged into a bag of normal saline, then connected to a high-flow stopcock at the distal end
    • Looked at IV catheters ranging from 14 to 22g
    • Fluid meniscus height of the normal saline was fixed at 60 to 120cm above the outflow point
    • The roller clamp on the infusion set was in the fully open position (“wide open’) for all experiments
  • Results:

Numbers Rounded to Closest Whole Number

  • Bottom Line:
    • Volume of fluid delivered by gravity-driven micro-drop infusion under “wide open” conditions is dependent on both the catheter size and the fluid column height

Paper #2: Reddick AD et al (Macro-Drip Setup)[2]:

  • What They Did:
    • Compare the flow rates of IV access catheters with different physical characteristics:
      • Pressure bag
      • Needle-free IV access connector
    • 1L of 0.9% saline solution was connected to each cannula at a height of 130cm above the infusion point (This is higher than the previous study – Range of 60 to 120cm)
  • Results:

  • Bottom Line:
    • The width of a peripheral IV cannula will have a predictable effect on the flow rate of fluids with 14g being the fastest and 22g being the slowest
    • The addition of a connector to the IV will slow down the flow rate being given

Discussion:

  • Flow through an IV will be dependent on your setup (For an 18g Peripheral IV):
    • “Wide open” micro drip at 120cm above your patient, to gravity ≈ 30 to 35cc/min
    • “Wide open” with macro drip with no connector at 130cm above your patient, to gravity ≈ 98.1cc/min

 

Original Video:

Follow Up Video:

Clinical Take Home Point

  • The best way/most precise way to give vasoactive medications to a patient is through a pump. Giving as a push dose is an excellent secondary option if a pump is not immediately available
  • It is not a great idea to do dirty epi drips, simply because there are just too many external factors that make it impossible to know how much epi you are exactly giving
  • The only situation I can see using a dirty epi drip is if you can’t stay at the bedside and there are no infusion pumps available (i.e. this is really a suboptimal approach)
  • If administering as a drip without an infusion pump, you must take into account a number of issues:
    • It is not precise, hence the name “dirty”
    • The measured height of the IV bag above the patient is also important and needs to be emphasized
    • Use a micro-drip setup to gravity which will give you a flow rate of about 30 to 35cc/min “wide-open”
    • Don’t use a macro-drip setup
      • If using a macro-drip setup to gravity the flow rate is closer to 100cc/min without a connector “wide-open”
      • If using a macro-drip setup to gravity the flow rate is closer to 80cc/min with a connector “wide-open”

References:

  1. Pierce ET et al. Medication and Volume Delivery by Gravity-Driven Micro0Drip Intravenous Infusion: Potential Variations During “Wide-Open” Flow. Anesth Analg 2013. PMID: 23400996
  2. Reddick AD et al. Intravenous Fluid Resuscitation: Was Poiseuille Right? EMJ 2011. PMID: 20581377

Post Peer Reviewed By: Anand Swaminathan, MD (Twitter: @EMSwami)

The post The Dirty Epi Drip and IV Flow Rates appeared first on REBEL EM - Emergency Medicine Blog.

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