Analgesia and Sedation

One of the original papers written in Feb of 2014 remains extremely pertinent and one that I have gone back to reference time and time again.

Download it now or read it in it’s entirety

PFC WG analgesia and sedation comments (Feb, 14)

SOCOM PFC WG Analgesia/Sedation Comments (February, 2014)

The following comments are summarized from a sub-group expert panel of the SOCOM PFC working group.

Please use these comments when considering case discussions and training of medics.

All comments are directed at the level of the SOF medic, and their training.

GENERAL COMMENTS:

PFC pharmacology is a core concept to be discussed in any training session.

Any discussion of PFC pharmacology should include a discussion about the CONCEPTS of analgesia, amnesia/anxiolysis, and sedation.

A reasonable formulary of “working drugs” for the SOF medic should include: morphine, Fentanyl, ketamine, and midazolam (Versed).  Adjunctive medications could include: narcan, romazicon, antiemetics, antihistamines, atropine and others.

The first time a medic administers these drugs should NOT be on a sick (unstable or complicated) patient.   Practice with their use.

As with any medication, a medic should be able to demonstrate an active knowledge of the pharmacology of any medication they are allowed to carry.    This should include: indications, therapeutic dosages, half-life, time for peak effect, contraindications, adverse effects, usual concentrations, pitfalls, and your personal strategy for dilution and administration.

Any procedure that involves sedation should also include monitoring the patient, ideally with end-tidal CO2 (with a waveform), and at a minimum, have oxygen saturation (pulse ox) monitoring.  Also, airway adjuncts, to include suction, BVM with oxygen source, and advanced airway equipment, should be available.

If a patient is too unstable, pain control and sedation should be withheld until the patient can be stabilized.

COMMENTS ABOUT THE AGENTS (in the context of the case study):

-There is a difference between analgesia (pain control) and sedation.  Some patients who appear to only need pain control MAY need sedation in order to perform prolonged evacuations (travel over rough roads, for instance).  Other examples of clinical scenarios that may require sedation include: chest tube insertion, cricothyrotomy, reduction of fractures or dislocations, large burn debridements, surgical procedures such as fasciotomies, and rapid sequence induction for intubations.

-The reason opioids have been around for centuries is they work.  This is in the case of the need for analgesia.  It is perfectly reasonable to treat >80% of patients with morphine.  Stable patients can get morphine.

-Hemodynamically unstable patients should get Fentanyl (or ketamine at pain control doses).  Remember, fentanyl and ketamine have very short half-lives and will need to be dosed and re-dosed.  A drip for analgesia can be very problematic and is NOT advised.

Fentanyl lollipops are effective and easy to administer.  1 x 800mcg lollipop, in its entirety, which hasabout 50% bioavailability, would be the equivalent of approximately 400mcg IV.  Do not discount this when adding drugs that are synergistic.  A major side effect of the lollipops is nausea.

-Get away from IM and go to IV meds as quickly as feasible.  There is a time for non-IV/IO administration, but that time ends with the establishment of IV’s and a couple of minutes to think through the process.  In a recent case study the patients received two different drugs through delivery mechanisms that make them very difficult to titrate.

-Mantra should be “titrate to effect,” as there is a range for every patient and tolerance.

Ketamine, in general, is an excellent medication if you understand its effects and pitfalls.  There are three ranges: effective pain range with little or no mental status effects (start with 10-20mg IV and titrate to effect), the mid-range where they’re still awake but agitated and actively hallucinating (0.3-1.0 mg/kg; 30-80mg IV), and the dissociated range where they’re sedated and dissociated: 1.0-2.0 mg/kg IV.  Decide ahead of time if you’re going high or low, but don’t get stuck in the middle.  This is also an excellent medication to induce unconsciousness prior to RSI (rapid sequence induction) prior to intubation (1.0 mg/kg IV push). PLEASE NOTE: these are all IV/IO dosages, NOT IM. IM dose for initial administration is 4X the IV/IO dose.

Versed (and other benzodiazepines) is a great drug.  Great for the correct indication, but there can be some serious pitfalls with its use, especially when added to other potent drugs.  Understand the synergy of benzodiazepines and opioids (synergistic effect).  Occasionally, it can drop blood pressures or over-sedate your patient.

Below is a recommendation for a sedation (notpure analgesia) mix that can be used to prepare and administer an infusion over time:

Basic principle:  ketamine drip with IV fentanyl bumps if needed.

Mix: 250ml bag of NS, filled with 750mg ketamine. The initial drip rate is KG body weight/2= cc/hr. For example a 100kg patient would be started at 50cc/hr drip rate.  At this rate, you can calculate the bag lasting about five hours. In practice, it is observed that the majority of the time, the drip rate could be cut in half after 20-30min, and the bag may last 8-9 hrs.  (For reference, the initial doses are: ketamine: 1.5 mg/kg/hr.

Remember, there is NO such thing as a cookbook.  BE VIGILANT and titrate the drugs to effect

3 thoughts on “Analgesia and Sedation”

  1. In some subsequent discussions about this after its publication last year, it seems with the ketamine drip, many experienced provides DO NOT use Versed (midazolam) mixed in an infusion – just ketamine alone. This would make things simpler and more accessible as a tool, especially if you had limited supplies. The main working drug is the ketamine.

    Many providers would absolutely recommend having a benzodiazepine available (midazolam is preferable due to its short onset and duration, but lorazepam (Ativan) or diazepam (Valium) could be a suitable alternative), either mixed in the drip or as pre-treatment to pushing ketamine, but this should not be seen as an absolute requirement for its use in the patient that requires sedation.

    The limited experience in training or practice with the use of ketamine, especially in adults in the US, may bias some providers and medical directors to not recommend its use, but there is a substantial body of literature, spanning decades, that support it’s use, especially in austere environments.

    We (WG members) would encourage all providers who may find themselves in austere environments to educate themselves in the benefits of this amazingly useful drug.

    Thanks, Sean

  2. Hey Guys thanks for the great resource, but in the article above you mention a Ketamine/Versed infusion, but no mention of the Versed and how much you mix into the 250mL bag of fluid. So for example if you have an 80kg patient then they are getting 4mg of Versed per hour. SO I take you’d have to load at least 20mg of versed to last 5 hrs? I know it depends… Also Ketamine has been touted to be given using IBW and not TBW from entities such as the Difficult Airway Course etc… Obviously there is no standard here and the military is kind of biased, meaning that most of their members they are basing their doses on are pretty close to IBW conditions. Thoughts? Thanks!

    1. Originally, our calculations were to put 25mg of Versed in the drip. This is a pretty hefty dose and I have since been recommending NO versed in the drip and just have it on hand to give as needed for delirium. This will conserve your supplies and probably be a better use of the medication. Also, when we wrote the CPG, most clinical pharmacists would NOT recommend mixing drugs in drips.

      With the drip, we first recommend a bolus dose of 1 mg/kg, then start the drip at a calculated dose of: kg/2 = mL/hr.

      As you observed, the active duty military population is closer to IBW than the regular population, but the dosing is such that in some CRNA’s experience, they are able to bring the drip rate down by 1/2 in some patients, so this is probably a higher starting dose, and would probably work for most patients, regardless of IBW vs. TBW calculations.

      You can always “bump” someone with 0.5-1 mg/kg push dose if they are getting light while you adjust the drip.

      When you do the math, though, your planning and packing considerations call for more ketamine than you might otherwise pack for “regular” TCCC use. Our standard pack-out for a longer deployment went from 2 vials to 10 vials of ketamine (500mg/vial).

      I know it should seem obvious, but these drips/drug doses are all IV/IO and NOT IM. Also, these higher doses IV are for sedation and not just pain control. As a reminder, the IM dosing for ketamine is approximately 4X the same dose IV/IO. Save your supplies; go to IV early!

      Hopefully, this answers some of your questions. Thanks, Sean

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