Rectal Methohexital according to Carl Chudnofsky and Conscientious Sedation

From his PaACEP resident lecture. For children who are undergoing painless imaging studies and would not otherwise require an IV.

Dose: 25 mg/kg

Typically comes in powder form for IV use, one vial = 500 mg.

Directions suggest that you reconstitute with 50 cc NaCl, which would = 10 mg/cc.

Chudnofsky method is to reconstitute with 5 cc NaCl, mix well to get all powder into solution, now you have 100 mg/cc.

Attach to syringe an 18g angiocath without needle.

Insert into rectum, not very far (1-2 cm in small child), inject slowly to keep fluid in rectum.

Close the buttocks together, hold with 3 inch cloth tape.

According to his study (PMID 10790471), average time to sedation = 7 minutes, average time to awake = 60 minutes. Note that of 100 patients, “Six had brief oxygen desaturations that responded to repositioning, although 3 of these also were given brief bag-valve- mask ventilation per institutional protocol. One developed a continuous cough. All had complete recovery and none required intubation.” So these patients have to be on a pulse oximeter and someone has to be ready to adjust airway, provide O2, and BMV as needed. I would round down the dose to closer to 20 mg/kg.

Conscientious Sedation

Patients who scream usually get my attention and things go something like this. Bypassing the protocol on a technicality (narcotics alone without sedatives are not “conscious sedation”), I administer rapid boluses of fentanyl (150 to 200 mcg usually suffice in total). Within a minute or two, the patient enters the most euphoric experience of her recent memory, closing her eyes and beginning to smile. I signal the surgeon who starts the procedure while the patient lazily registers the discomfort, but when offered more pain medication claims “it’s OK.” I hang out in the room during the procedure, adding fentanyl if needed and catching up on paperwork. Meanwhile, content surgeons, who despite their hard shells do prefer a nonsuffering patient, wrap it up in style. When all is done, the patient looks at me with immeasurable gratitude, and I recall all the reasons for which I became a physician. My term for it: “conscientious sedation.”

It uses up ED attending time, but for all the right reasons. I start with half the intended final dose for the rare hyperresponder. There is naloxone in my pocket and I’ve never had to use it. I am ready to intubate should the need arise, but I doubt it will. I memorized side effects of fentanyl and consider risk-benefit beforehand. And yes, I think it is an adequate approach to procedural pain for most ED interventions on typical adult patients, especially when local anesthetics are appropriately used.

from: Veysman, Boris D. Annals of Emergency MedicineVolume 56, Issue 4, October 2010, Page 430