Michael Irwin

Michael Irwin

Daniel CK Yu Professor in the Department of Anaesthesiology, Hong Kong University
Editor of Anaesthesia, Perioperative Medicine, Expert Opinion on Pharmacology


  • Sorry I didn't see your message. I'm not sure why this would be. It is best to e-mail Future Learn directly with your concern

  • You're correct thanks

  • @LynnWright we use 16 mg dex. Mostly SA with plain bupivacaine and fentanyl

  • You would think so but it actually doesn't really matter which model you use as long as you titrate up - after all it is the same drug, just different infusion model. It helps also if the predicted effect site is fairly accurate and that is not the case with Schnider. Schnider may give the impression of less CV effect simply because it gives a low dose.

  • MAC is just a statistical construct that is useful only as a guide. If you use MAC (even age adjusted) it is only optimal for some of your patients (median). You can't titrate up inhalational agents like you can with TCI

  • This is not exceedingly deep. Beginners guide! We are all professionals and take pride in knowing our work well

  • Thanks - we are considering a more in depth course for those more experienced

  • TIVA with TCI is the best anaesthesia TITRATION technique. Start LOW and go SLOW in vulnerable. Be patient - propofol is a slow onset drug

  • There is a certain capital cost but it is not an expensive technique thereafter. We argue that TIVA should be part of mainstream anaesthesia education as it is now in most countries

  • Never too late :)

  • Thanks for your feedback!

  • @DRMUKESHVALECHA usually fentanyl bolus as required. Cheap and effective. Morphine if postop pain anticipated

  • May take a little more time for induction but better recovery and not more expensive than sevo or des

  • Glad you are using raw EEG Alice!

  • Thanks Philippe - keep up the good work!

  • You don't really need pEEG if the patient is not paralysed, although I agree it can be helpful with depth

  • PRIS is extremely rare. Seldom reported in adults. Usually prolonged ICU sedation - particular caution in children with neurological disorders and prolonged ICU sedation (monitor for acidosis). This is not a concern with routine intraoperative use but, as we stated, use propofol for LOC - high doses are not required when using analgesic adjuncts.

  • Propofol TIVA is cheaper than sevo, this has been shown in several centres. There is no medicolegal issue with using an established technique which has clear patient benefits. Setting up a registry is a great idea. If you use TIVA regularly, you will find not much delay in starting and a significant advantage in recovery. What is best for the patient is good...

  • I agree the cost of pumps may be an issue, but most TIVA drugs are now generic and relatively cheap. I don't see any significant disadvantages and what is the problem with surgeons?? Whatever is best for patients is good for the whole team!

  • Gracias por tu comentario. Es por eso que se necesita hacer más para promover los beneficios de TIVA y mejorar la educación

  • I agree. Also lidocaine doesn't seem to have a "preventive" analgesic effect (analgesia wears off v quickly after cessation) and there have been serious adverse incidents with postoperative infusion

  • Thanks Anup, hope you are well!

  • The Bristol regime is a reasonable, albeit simple concept but TCI is the way to go if you can get it

  • Many thanks for your encouraging feedback!

  • Yes. IMO propofol should be administered to achieve loss of consciousness and an analgesic (e.g. opioid) to block pain (nociception). If propofol is used alone, much larger doses are required to obtund nociception, and this may not be brain healthy. The important concentration is the effect site (not plasma/blood) as this is the concentration at the site of...

  • @LucyPowell I note the previous responses which I agree with. It also depends somewhat on the drug Pk/Pd e.g. fentanyl is quite a slow onset drug (3-5 min peak effect) so giving it first is prudent, whereas remi and alf have a much quicker onset.

  • I agree. We are trying to educate with this website, workshops and our textbook. The "faff" becomes less of an issue, the more familiar and comfortable one becomes using TIVA. V short cases can even be managed with manual infusion etc.

  • Both are major issues in many countries, a reason why we have set up this teaching website. The equipment is not necessarily expensive and most TIVA drugs are now generic. It is important to make a stand for the best perioperative care for our patients

  • If you use ketamine, I wouldn't think there is significant incremental benefit with Mg unless you want the effects on BP

  • I would prefer ketamine to Mg. They both work on NMDA but ketamine is more powerful and may even have positive effects on mood. Studies suggest less efficacy with Mg and you need to be careful with muscle relaxants

  • Dex is a great drug. Excellent and safe sedative and a very good GA adjunct

  • That's great if you have it but there is less need for pEEG if the patient is not paralysed

  • As more information becomes available on Eleveld, we will update. Thanks for your feedback and suggestion

  • This is all fine. I just don't like benzodiazepines because of the association with postoperative cognitive dysfunction and delirium

  • Schnider is less accurate than Marsh and the time to peak effect (time to reach predicted effect site concentration) is misleadingly fast which makes titration difficult. Anyway now you have Eleveld so just use that. The book is very good but we felt there is a need for a more practical text and are now working on our second edition

  • Yes this is also reasonable but 400 mg daily may be better for some

  • Sorry to hear this. My apologies and I'll look into it

  • Good suggestion. Also have a look at this few download article by Emery Brown: https://pubs.asahq.org/anesthesiology/article/123/4/937/12574

  • Hi Lucy. Please see Yu EH, Tran DH, Lam SW, Irwin MG. Remifentanil tolerance and hyperalgesia: short-term gain, long-term pain? Anaesthesia. 2016 Nov;71(11):1347-1362. doi: 10.1111/anae.13602. PMID: 27734470
    Free download from Anaesthesia journal website. A few years old but v unlikely to get clinically relevant hyperalgesia with normal use of remi. Some...

  • @NAVINATHIAGARAJAH very seldom, especially with MCT/LCT propofol. Some mention a numb feeling or mild discomfort if the vein is small but really I never find this to be a clinical problem

  • Hi Adrian. I have written an article on this topic available as a free download on Anaesthesia journal website. Essentially this is not a concern with correct clinical use https://doi.org/10.1111/anae.13602

  • @LucyPowell Thanks Lucy, good points especially concerning older docs who may, understandably, resistant to change