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Milk of Amnesia

Ah Propofol, critical cares best friend, and yet so much misinformation regarding its use and action exists.

Propofol (Diprivan) is probably one of the most easily recognizable medications due to its delivery in glass bottles and its milky white appearance, but be careful, as it is not the only medication that appears this way (see my previous post on clevidipine).

Propofol gets its unique appearance from the emulsion it is prepared in which most commonly is a combination of soybean oil, egg yolk lecithin and glycerol. The lipid-based emulsion actually acts as a vehicle for the lipophilic propofol in order to keep it evenly dispersed and maintain stability. There are drawbacks however such as the propensity for microbial growth, hyperlipidemia, calorie consideration and injection pain.

Propofol is an anesthetic and hypnotic that potentiates the inhibitory transmitters glycine & GABA which in turn enhance spinal inhibition.

It is used mainly in the ICU in the form of a continuous infusion to maintain sedation for those patients who are intubated or undergoing a procedure. Within the emergency department it can be used similarly but is also used in RSI or for moderate sedations for procedures such as orthopedic reductions, intracranial bolts, or just for pediatric populations in order to suture or place a central line. In this type of setting it is not uncommon for the ER doc to mix the propofol with an analgesic or dissociative such as ketamine (creating ketafol, more on this in a later post).

Propofol is NOT an analgesic, so must be paired with one if the patient is in pain. It is favored for sedation in neurologic cases as the half-life is much shorter than other sedatives and it decreases ICP. In fact, its onset is approximately 30 seconds and its duration can be as little as 10 minutes unlike benzodiazepines which can accumulate and last days.

Upsides to propofol in addition to its quick half-life are that it is also a potent bronchodilator and an effective anti-convulsant. Its also an enti-emetic and when compared to other sedatives, is relatively cheap.

Perhaps propofols largest downside is its potential for profound hypotension. Patients who are already hypotensive and hemodynamically unstable should not receive propofol as it will reduce blood flow to vital organs and decrease cerebral profusion. Propofol also has no reversal agent so extra caution and assesemtn should be taken prior to administration.

Becasuse of propofols classification as an anaesthetic protocols vary heavily regarding its use by RNs. Most states and Boards of nursing allow registered nurses to administer propofol via continuous infusion and titrate per MD order as long as the RN is working in a critical care environment and the patient has an artificial airway in place.

The grey area comes when administering propofol via a syringe 'push', either as a loading dose, bolus or induction agent. Some states allow RNs to push, but the BON is against it. Other states BON allow RNs to push but the state does not. And to add to the confusion some states and BONs allow pushes, but the hospital protocol does not. In any case, it is probably wise to have the MD push the drug, especially if the patient is not intubated, solely to protect your job and your license.

[update] Upon researching different states' BON stance on pushing anesthetics, it was found that many have a position on the matter, but it is non-specific and vague while others are specific to what type of patient population and use of drug.

California BON example:

"It is within the scope of practice of registered nurses to administer medications for the purpose of induction of conscious sedation for short-term therapeutic, diagnostic or surgical procedures

No limits are placed on the type of medication or route of administration.

The RN does not have the authority to administer medications which would result in deep sedation and/or loss of consciousness"

Oregon BON example:

"The Oregon State Board of Nursing affirms that it is within the role and scope of practice for the RN, NP and CNS to administer sedating and anesthetic agents to produce moderate and deep procedural sedation and moderate and deep sedation for the non-intubated or intubated/ ventilated patient, provided that the nurse have the specified knowledge and skills and specified requirements are met.

The RN, NP or CNS may also manage patients who are recovering from sedation. In addition, there are other special circumstances in which a nurse, under the direction of a LIP, may use Ketamine in non-intubated patients provided appropriate criteria are met"

Pennsylvania BON example:

"A registered nurse who is not a certified registered nurse anesthetist may administer intravenous conscious sedation medications during minor therapeutic and diagnostic procedures"

Propofol is dosed based on its intended purpose, but as critical care nurses our most common use will be for continuous sedation of ventilated patients.

Thus, the standard dose is 5-50mcg/kg/min titrating to desired effect.

Induction doses tend to be 1-3.5mg/kg followed by a drip.

In instances of immediate needed sedation, 10-20mg/push may be given (not by RN) if patients BP allows.