Procedural Sedation and Analgesia - Part 2

David Elkin · August 5, 2020 · Procedures

For those of you following along from PSA Part 1...the answer to the question at the end is ketamine!

For Part 2, we’ll be discussing the most commonly used Procedural Sedation and Analgesia (PSA) agents including their classifications, recommended doses, peak effects, durations, and some comments that I think are noteworthy about each of them as they relate to PSA. And yes there's more than just ketamine!

Remember for our purposes when we discuss PSA, our goal is usually moderate to deep sedation!

Commonly used agents:

Midazolam (Benzodiazepine)

anxiolytic, sedative, amnestic, muscle relaxant, anticonvulsant

Dose: 0.05 - 0.1 mg/kg IV; 0.1mg/kg IM

Peak effect: 2-3 mins IV; 15-30 mins IM

Duration: 20-30 mins IV; 1-2h IM

Comments: May produce paradoxical excitement.

Can use flumazenil as a reversal agent.

Does not provide analgesia (sometimes given with opioid).

Can cause hypotension and respiratory depression.

Fentanyl (Opioid)

analgesic

Dose: 1 - 3 mcg/kg IV

Peak effect: 2-3 mins

Duration: 30-60 mins

Comments: Typically used in conjunction with another agent for pain relief.

100 times more potent than morphine but much shorter acting.

Relatively safe hemodynamic profile, rarely causes hypotension.

Can cause respiratory depression.

Can use naloxone as a reversal agent.

Commonly observed reaction is nasal pruritus so patients will try to scratch their nose.

Rare but serious side effect to remember is that it can cause Rigid Chest Syndrome, usually in pediatrics and usually with larger doses. Can attempt rescue ventilation in this case but will likely need to reverse with naloxone or possibly give paralytic and intubate.

Can give intranasally for immediate pain relief prior to a PSA and if applicable, before IV access is established (more commonly done in pediatrics).

Pentobarbital (barbiturate)

sedative, amnestic, anticonvulsant

Dose: 2.5 mg/kg IV

Peak effect: 3-5 mins

Duration: 15 mins

Comments: Can lead to respiratory depression and hypotension.

Apparently the IV sedative of choice for children in many diagnostic imaging centers for its quick onset and short duration of action and considered superior to midazolam.

Ketamine (NMDA receptor antagonist)

dissociative, analgesic, amnestic

Dose: 1mg/kg IV; 4mg/kg IM

Peak effect: 1-3 mins IV; 5-20 mins IM

Duration: 15-30 mins IV; 30-60 mins IM

Comments: Everyone’s favorite in EM and probably deserves its very own post.

Not considered a sedative in the classic sense because of its dissociative properties.

Can cause bronchodilation and bronchorrhea resulting in excessive salivation.

Can cause transient apnea and transient laryngospasm. If suspecting laryngospasm, can try jaw thrust using the laryngospasm notch maneuver. If that doesn’t work can try bagging through. If still unable to ventilate, will need to give paralytic and intubate.

Can cause a profound emergence reaction and is contraindicated in patients with schizophrenia and psychosis. Emergence reaction is less common in pediatric patients. One way to prevent this recovery agitation is by helping the patient go into the “K-Hole” smoothly prior to and during medication administration by helping them think happy thoughts, having them think of their favorite place, or maybe even doing some magic therapy (for more info: www.magic-aid.org). If patient is having a very agitated emergence reaction and calmly talking to them/trying to redirect them does not work, can give a dose of midazolam or propofol to help calm them. Would not recommend magic therapy on a patient with emergence reaction.

Can cause emesis, typically in the recovery phase. Can give ondansetron in recovery phase. No evidence that co-administration of ondansetron with ketamine reduces incidence of nausea in recovery phase.

Can cause muscle rigidity.

Typically pushed slowly but no evidence to show that this reduces incidence of laryngospasm or nausea, contrary to popular belief.

Sympathomimetic properties which cause inhibition of catecholamine reuptake results in increase in blood pressure and heart rate. This means that in a critically ill patient who is on multiple pressors and is out of native catecholamines, ketamine actually causes myocardial depression.

Can give IM before IV access is established and maybe not even start an IV if you don't need one (more commonly done in pediatrics).

Etomidate (GABA agonist, positive modulator of GABA receptor)

sedative, anxiolytic

Dose: 0.15 mg/kg IV

Peak effect: 15-30 secs

Duration: 3-8 mins

Comments: No analgesic property.

Hemodynamically stable.

Fast-on and fast-off.

Can possibly cause adrenal suppression in septic patients although likely irrelevant for one time dose for PSA.

Can cause respiratory depression, myoclonus, vomiting.

Can lower seizure threshold. Do not give to someone with epilepsy.

Propofol (positive modulator of GABA receptor)

sedative, anxiolytic

Dose: 0.5 - 1 mg/kg IV

Peak effect: 30-60 secs

Duration: 5-6 mins

Comments: No analgesic property.

Hurts going into vein, can pretreat with lidocaine or mix with lidocaine.

Can cause transient apnea, respiratory depression, hypotension.

Fast-on and fast-off.

Can cause muscle relaxation

Common teaching has been to avoid in patients with known or suspected allergy to eggs or soy products but this has been debunked.

“Ketofol” (combination of ketamine and propofol)

Dose: ketamine 0.125-0.5mg/kg + propofol 0.5mg/kg IV

Peak effect: 30-60 secs

Duration: 15 mins

Comments: Can either give 1:1 or give subdissociative dose of ketamine with PSA dose propofol.

These agents supplement each other: ketamine mitigates propofol-induced hypotension and propofol mitigates ketamine-induced vomiting and recovery agitation.

Some commonly encountered procedures requiring PSA and what I like to use (just in general, always take into account specific patient factors):

Cardioversion = etomidate + fentanyl

Complicated pediatric laceration repair: ketamine

Fracture/Joint reduction (recently dislocated): ketamine

Adult Joint reduction (delayed presentation): ketamine + propofol

What are your thoughts? Do you have any favorite go-to procedure-drug pairings?

Stay tuned for PSA Part 3 where we put everything together and discuss the setup and procedure!

Procedural Sedation and Analgesia - Part 1

David Elkin · July 31, 2020 · Procedures

Procedural sedation and analgesia (PSA) is the use of analgesic, sedative, and/or dissociative agents with the purpose of relieving pain and anxiety associated with a procedure.

It is well within the scope of the emergency physician and the aim of this post is to go over some key points as well as go over some of the most commonly used agents.

First thing to remember is that sedation is a spectrum and our goal state is determined by our indication for PSA including the duration of the procedure, and the level of pain/anxiety associated with the procedure.

We can then achieve our goal by careful selection of the proper agent, route, and dose.

Also take into account the patient’s age and comorbidities, including hepatic, renal, and cardiopulmonary insufficiencies.

For our purposes, PSA will only be referring to moderate sedation.

Our goal for PSA is to induce a state that allows a patient to tolerate unpleasant procedures while maintaining cardiorespiratory function by producing a depressed level of consciousness but allowing the patient to maintain airway control independently and consciously.

Before getting into the different agents, here are some definitions to be familiar with:

Analgesia: Relief of pain without intentional production of an altered mental state such as sedation. An altered mental state may be a secondary effect of medications administered for this purpose.

Anxiolysis: State of decreased apprehension concerning a particular situation in which there is no change in a patient’s level of awareness

Dissociation: Trancelike cataleptic state in which the cortical centers are prevented from receiving sensory stimuli, but cardiopulmonary activity and responses are preserved.

Can you guess which PSA agent was used on this pediatric patient?

Find out next time in our PSA POTD - Part 2!

Joint Aspiration: Ankle

Sirivalli Chamarti · October 22, 2019 · Orthopedics, Procedures, Ultrasound

When to tap?

When you have a debilitating ankle injury with swelling at the tibiotalar joint preventing range of motion at that joint ie: dorsiflexion/plantarflexion.

What about the differential?

Ankle arthrocentesis allows for rapid identification of septic arthritis vs. gout vs. pseudogout vs. osteoarthritis vs. rheumatoid arthritis.

What are your landmarks?

The goal is to avoid the Dorsalis pedal artery, the peroneal nerve and the tendon of the Extensor Hallucis Longus (EHL). It is recommended to use an anterolateral approach where the joint line can be found between the lateral edge of the EDL and the medial edge of the lateral malleolus (Yellow Arrow Image 1). Plantarflex the ankle while the patient is bent at the knee in the supine position to widen the joint space prior to performing the procedure.

IMAGE 1:

How do you perform it?

1. Patient should be in a supine position with the ankle in plantar flexion with plantar surface flat on the bed.
2. Mark you landmarks (see above).
3. Prepare the site (ex. chloraprep)
4. Anesthetize the area with smaller needle(23/25 gauge) creating a wheal and then advance creating the start of a projected path towards the joint capsule.
5. Attach a 5 or 10 cc syringe to a 20 or 22 gauge needle and advance the needle into the joint space pulling negative pressure as you advance. The needle should be directed perpendicular to the tibia. If your syringe starts to fill up, and you need to get more fluid out, change out your syringe using hemostats to hold the needle. Most wrist and ankle effusions will yield only 1-3cc of fluid.

What about Ultrasound Guidance?

YES. This can absolutely be used to assist you in performing the procedure and will allow for visualization of your needle tip during aspiration.

For ultrasound guidance an anteromedial approach is generally used.

Landmarks- Place probe in between the TA tendon and EHL tendon, then rotate longitudinally with the probe marker facing the patient’s head (Blue Arrow IMAGE 1). You will actually be inserting your needle medial to the TA tendon (Red Arrow IMAGE 1).

Image 2: