Archive for the ‘PSA & analgesia’ Category

The Harms of Fasting

May 16th, 2014
by reuben in PSA & analgesia, radiology

The following is adapted from my contribution to this discussion of how best to manage unfasted patients who require deep sedation to facilitate a painful procedure. I am responding mostly to Nicholas Chrimes, a thoughtful Australian anesthesiologist behind The Vortex Approach to airway management.  Because aspiration leading to clinically relevant morbidity is a rare event and is often not straightforward to identify, we do not know which patients are most at risk, which sedation procedures confer greater risk, or how to reduce that risk (by, for example, fasting). Standard of care is therefore based on tradition and opinion which I believe is largely misguided and contrary to the interests of patients and providers. Though the focus of the discussion was on whether patients not known to have an empty stomach are better off receiving spontaneously breathing procedural sedation or RSI/endotracheal intubation, I was most struck by what felt to me a lack of appreciation of the harms of fasting. The harms of fasting are not adequately represented in this debate, so I think the topic is worth elaborating. Nick: The notion that, during PSA, aspiration causes clinically important harm with an appreciable frequency, or that this frequency can be reduced by fasting, is contrary to the outcomes and opinions reported in these registries and reviews: Smally 2011 Thorpe 2010 Molina 2010 Roback 2004 Agrawal 2003 Ghaffar 2002 Treston 2004 Bell 2007 Babl 2005 McKee 2008 There are over 20,000 ED PSA cases reported in the literature, and, to my knowledge, two (2) reported clinically consequential aspiration events. In one…

The Ketamine Brain Continuum

December 25th, 2013
by reuben in PSA & analgesia

You’re cardioverting an otherwise healthy 100 kg 48 year old man with lone afib. Since cardioversion is a brief procedure, you decide on a smaller than usual dose of ketamine, 50 mg.  You push the ketamine and prepare the defibrillator. The patient develops a far off stare, seems like a good time to shock, and you’re about to do just that, when he starts screaming at the top of his lungs I’M DYING!! I’M DYING!! I CAN’T SEE ANYTHING!! HELP ME!! You try to reassure the patient but he seems unable to hear you, and is now shrieking with great emotion that his body has disappeared. Nearby patients and staff are visibly disturbed and your med student started to cry, then fled. What’s going on? How do you manage this distressing situation and prevent it from happening again?   Ketamine was developed in the 1960s in a successful effort to synthesize a dissociative anesthetic that didn’t make people as crazy as phencyclidine, PCP, which was developed in the 20s. Its effect on cognition is attributed to antagonism at the NMDA receptor; this action interferes with the transmission of information that starts outside the brain from getting into the brain. In high doses, NMDA antagonism leads to dissociation, a cataplectic state where the patient maintains airway reflexes and cardiorespiratory function but cannot perceive any external stimuli nor interact with the world in any way. The ability of ketamine to produce dissociation is of great value to clinicians who perform painful procedures, and this practice is firmly…

Three part screencast covering the essentials of procedural sedation and analgesia for emergency clinicians. Part one covers how to think about and prepare for PSA, including a discussion of fasting guidelines. 13 minutes. Part two describes how patients are harmed during PSA and how to prevent patients from being harmed during PSA. 29 minutes. Part three discusses contemporary PSA pharmacology. 16 minutes.   References Slideset Emergency Department PSA Checklist  

  Designed to be used as a single, double-sided page.  pdf for printing pdf vector image for screen viewing for PSA mastery, see the PSA screencast trilogy If you’d like to modify the checklist for your institution, I can send you the original layout (omnigraffle format) and tables (excel format). Update: Egg and soy allergy is NOT a contraindication to propofol. Update: ACEP’s procedural sedation clinical policy stipulates “Do not delay procedural sedation in adults or pediatrics in the ED based on fasting time. Preprocedural fasting for any duration has not demonstrated a reduction in the risk of emesis or aspiration when administering procedural sedation and analgesia.” See the harms of fasting.

Dexmedetomidine (trade name Precedex) is an alpha-2 receptor agonist, similar to clonidine. Whereas clonidine provides a robust decrease in blood pressure with mild sedation, dexmedetomidine provides robust sedation with a mild decrease in blood pressure. It does not depress airway reflexes or respiration. It has a variety of potential uses in the emergency department, including procedural sedation, the facilitation of awake intubation or noninvasive ventilation, and the treatment of alcohol withdrawal. For these indications, however, we have agents that are at least as good, familiar, and a hell of a lot cheaper. Sedation for painless procedures in children is the scenario that may push dexmedetomidine into the emergency physician’s toolkit. Kids who require sedation for CT or MR imaging would ideally be managed without placing an IV (nix etomidate), using an agent that does not cause significant cardiorespiratory depression (nix barbiturates), is otherwise safe (nix chloral hydrate, which is also unpredictable, untitratable, and lasts forever), and reliably causes kids to be still (nix ketamine). This case series reports on 65 consecutive children sedated for CT or MRI with intramuscular dexmedetomidine, administered either once or twice at a dose of 1-4 mcg/kg, the exact dose left to provider discretion, to achieve a target Ramsay score of 4 (asleep but briskly responsive to a light stimulus). 4 patients out of 65 required a second IM dose to achieve a Ramsay score of 4. Once Ramsay 4 was achieved, no other agents were given for the duration of the procedure. The mean dose was about 2.5 mcg/kg. All 65 children…

This post has been replaced by the PSA Checklist V2.   Designed to be used as one double-sided page. Available in pdf form. If you’d like to modify the checklist for your institution, I can send you the original layout (omnigraffle format) and tables (excel format).

Taming the Ketamine Tiger

January 27th, 2011
by reuben in PSA & analgesia

In this month’s Annals of Emergency Medicine, Sener et al report on their nicely blinded study where 182 adult subjects were randomized to one of four groups – IV or IM ketamine (at dissociative doses), with or without IV midazolam (.03 mg/kg). They conclude that midazolam reduces the incidence of recovery agitation based on their results: Green and Krauss provide an accompanying editorial where they caution that the treatment effect as reported by Sener might be exaggerated and conclude: “Given this compelling evidence from Sener et al, many clinicians will choose to ‘tame’ ketamine in adults by routinely coadministering midazolam. Others, according to the caveats above, will just as reasonably elect to individualize such prophylaxis, using a subjective assessment of a given patient’s risk. After all, should their prediction fail and an unpleasant reaction result, it can readily be quelled with midazolam. Regardless of these approaches, the ketamine ‘tiger’ may not be as ferocious as some fear.” In my 2008 catalog of ketamine adverse events in adults, I describe three strategies for dosing midazolam–predissociation, preemergence, and PRN. I use the PRN strategy, and in hundreds of sedations of adults, I’ve needed to use it once. Here is my accumulated wisdom on how to use ketamine. * Use ketamine. No other agent matches its safety, efficacy, and reliability. The only patients who should not receive ketamine are patients in whom an increase in heart rate or blood pressure would really concern you. All the other variously reported contraindications, including oral procedures and especially the concerns around…

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…

PO administration of IV ketamine

March 7th, 2010
by reuben in PSA & analgesia

Needle-less procedural sedation / sedation for imaging: “After extensive discussion with the patient’s parents and NICU staff, the PPM service recommended oral administration of intravenous ketamine (10 mg?mL, Monarch Pharmaceuticals) at a starting dose of 0.5 mg (0.125 mg?kg?dose). Over 4 days, the dose was titrated to 3 mg (0.75 mg ? kg ? dose) in response to observed effect. At 15 minutes after a dose of 3 mg of ketamine, the patient was able to tolerate her dressing change without crying or resisting for 45 minutes (Figs. 1 and 2). Her ability to feed afterward was preserved. No effects on depth or rate of respiration were noted.” Saroyan et al, Pediatric Dermatology 26:6 Nov/Dec 2009 764-766.