Christian Inchaustegui, MD

Updated the chapter on extubation 😁 Determining whether the patient "passes" an SBT is perhaps the biggest clinical conundrum. Rapid-Shallow Breathing Index (RSBI) is commonly used to gauge whether the patient passes an SBT. However, this is only moderately predictive of the ability to extubate: 👍 RSBI <105 indicates +2 likelihood ratio of successful extubation 👎 RSBI >105 indicates a 0.3 likelihood ratio of successful extubation RSBI <105 doesn't guarantee success, because it only measures if the patient is strong enough to breathe (the patient may still fail to clear secretions or maintain their airway). RSBI >105 doesn't guarantee failure. Especially in the context of chronic respiratory dysfunction (COPD, ILD), patients may still be extubatable (especially extubation of COPD patients directly to BiPAP). Ultimately, there's no easy answer. Clinical judgement and experience are needed. Vibes. Often you need to repeat the SBT and see exactly what happens and how the patient "failed." There is only ONE test with 100% sensitivity and specificity for the ability to extubate: removing the endotracheal tube and seeing what happens. Patients continue to surprise me and remind me that we cannot foresee the future, so sometimes we need to just empirically try. The main improvement to the chapter is better organization with quick links to commonly encountered problems. (#1/2, link in next post) #AlwaysBeExtubating

New IBCC chapter on CT scan for patients with a history of contrast allergy 😁 Some key points: ☢️ If contrasted CT is emergently necessary (e.g. stroke, trauma) just get it. Full stop. ☢️ If the contrast allergy reaction occurred before 2000 it's likely due to oudated high-osmolal contrast dye. You don't need to worry about this, just get the scan. (Canadian guidelines) ☢️ Define the severity of the prior reaction. Unless it was *severe* and resembling an allergy (e.g. anaphylaxis, vital sign abnormalities) you don't need to really worry about it. ☢️ Antihistamines *do* probably reduce the risk of mild contrast reactions (e.g., urticaria). If you want to give a dose of oral nonsedating antihistamine that's fine (eg cetirizine 10 mg PO). Antihistamines don't save lives or prevent anaphylaxis. And you don't need to give a big bomb of IV diphenhydramine. ☢️ The best available data suggests that pre-scan steroids don't prevent severe reactions. Canadian guidelines say not to give steroids. Historically the American Allergy guidelines have also recommended not giving steroid. The most recent American College of Radiology plus American Allergy consortium guidelines (below) say to "consider" steroid (figure below). That means exercise your best judgement about risks vs benefits. ☢️ If you do decide to give steroid you can give a single dose of 200 mg IV hydrocortisone or 40 mg IV methylprednisolone 4-8 hours before the CT scan. You don't need to give multiple doses of steroid. You don't need to wait a billion hours before the scan. Hydrocortisone probably makes the most pharmacokinetic sense because it's relatively short-acting and has low CNS penetration (less delirium). ☢️ Changing to a different formulation of contrast dye DOES probably help *if* you can get this done. Unfortunately patients often don't know what type of contrast dye they received previously. Also, most hospitals only have access to a couple types of contrast dye. So this works better in theory than reality. ☢️ No matter what you do there is always a nonzero risk that the patient may develop anaphylaxis after CT scan. This should be treated aggressively with epinephrine per usual. There's no way to get the patient to zero risk. Trying to get to a zero-risk situation will actually cause delays and harm. #1/2 (link in next post)