Archive for the ‘radiology’ Category

The Harms of CT

January 16th, 2017
by reuben in radiology

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…

Treatment of Extravasation

April 17th, 2011
by reuben in radiology

Treatment of Extravasation Emergency physicians often manage IV catheter malfunction causing extravasation, which can result in significant tissue necrosis. Hyaluronidase may significantly reduce tissue injury from extravasation by hydrolyzing mucopolysaccharides present in connective tissue. This results in a transient increased permeability of the tissue and subsequently enhances diffusion of liquids through the subcutaneous space. Although the irritating medication is distributed over a wider area, quick absorption minimizes tissue injury. Hyaluronidase has been shown to reduce the extent of tissue damage following extravasation of parenteral nutrition solutions, radiocontrast media, phenytoin, promethazine, dextrose, mannitol, and the vinca alkaloid chemotherapeutic agents (e.g. vincristine, vinblastine). Hyaluronidase is well tolerated and has been used in neonates as well as adults. Administration techniques differ, but most sources recommend making a ten-fold dilution of a 150 unit vial of hyaluronidase in NS to provide a concentration of 15 units/ml, then dividing the dose into 0.2 ml subcutaneous injections via a 25 gauge needle in 4-5 different sites along the leading edge of erythema. Hyaluronidase is most effective if administered within the first 2 hours after an extravasation, however, it may still be beneficial when given up to 12 hours after the event. References: (1) Wiegand R, Brown J. Am J Emerg Med 2010;28(2):257.e1-2. (2) Cochran ST, et al. Acad Radiol 2002;9 Suppl 2:S544-6. (3) Kuensting LL. J Pediatr Health Care 2010;24(3):184-8. (4) Sokol DK, et al. J Child Neurol 1998;13(5):246-7. from:

Enough already with this nonsense. Schabelman & Witting. The Relationship of Radiocontrast, Iodine, and Seafood Allergies: A Medical Myth Exposed. The Journal of Emergency Medicine, 2010 39:5 701-707.   The evidence suggests that asking if patients are allergic to shellfish or iodine has no relevance to radiocontrast allergies. This questioning perpetuates the myth of an association between shellfish, iodine, and contrast agents. Instead, ask if they have any allergies, have had a previous reaction to a contrast agent, or have evidence of atopy, such as asthma. Educate nurses and technicians to stop propagating this myth as well. If your patient offers an allergy to iodine or shellfish, ask the patient if they mean to say that they have had a reaction to intravenous contrast in the past. Educate them that they do not have an “allergy” to iodine, and that an allergy to shellfish does not change the risk of reaction to intravenous contrast any more than any other allergy. If your hospital does not routinely use a low osmolarity, non-ionic agent, request this type of medium for atopic patients, patients who had a reaction to an intravenous contrast agent in the past, and patients with systemic disease that increases their risk for contrast reaction. Do not delay emergent studies for steroid premedication. Only lengthy 12h premedication protocols have shown any effect on reaction rates, and this small benefit was manifested primarily by decreasing minor reactions. No steroid protocol has shown a significant benefit in decreasing severe or fatal reactions. Monitor all patients for at least…

(Risks described are approximations for a 45-year-old person; risks are halved for 70- year-olds, doubled for 20-year-olds, and quadrupled for young children) “Mr. Smith. The best way I can diagnose your pain is a CT scan. This means having radiation exposure. I will explain how much radiation. You are always exposed to ‘background’ radiation from the ground, stars, air, and food. To use money as an example, it is 2 cents per hour. For comparison, a chest x-ray is $2 and the abdominal CT scan is $1,000 of radiation. Risk of cancer during your lifetime increases by about 1 in 1,000 for every $1,000 of radiation exposure. Of 1,000 people, about 420 will have cancer in their lifetimes. Therefore, every $1,000 of radiation increases the cancer risk from 420 to 421 of 1,000. About half the cancers are fatal. You can see that the risk of cancer from the CT scan is low. For every 1,000 patients getting your scan, only 1 will probably get cancer because of it. I recommend the scan for you because I believe the benefit of diagnosis outweighs the risk. If you disagree, we can discuss other options that avoid radiation exposure, but these may be less helpful in diagnosing your pain. A delay in diagnosis also carries a risk of complications or death.” Veysman, Acad Emerg Med 2009 16:1 p95 also CT Consent 2011 also, from Michelle Lin:   also, from Safety of Radiographic Imaging During Pregnancy: Am Fam Physician. 1999 Apr 1;59(7):1820.