Episode 191: Preop assessment for ambulatory surgery with Bobbie Sweitzer

In this episode I welcome Dr. Bobbie Sweitzer to the show to discuss how to identify high risk patients for ambulatory surgery in order to reduce the risk of postop complications. We review important perioperative guidelines and how the patient population for ambulatory surgery is changing.

Random Recs:

Oreo Cheesecake: https://preppykitchen.com/oreo-cheesecake/

Malcolm X Biography: Link

Dr. Sweitzer’s book:

7 Replies to “Episode 191: Preop assessment for ambulatory surgery with Bobbie Sweitzer”

  1. Great episode and thanks.

    As far as the DAPT guidelines… They are complicated, but I actually really like them. Europe, Canada and US all put out DAPT guidelines that are quite similar within 3 years of each other.

    From listening to Dr. Sweitzer, I got the impression that “therapy duration” was conflated with “interruption”.

    I liken it to Afib/Anticoagulation. In the case of Afib, it’s lifelong (basically) anticoagulation but interruption is safe.

    The various cardiology registries (e.g. PARIS) suggest that interruption during the “duration of therapy” phase is quite safe even at the 30 day mark. The DAPT guidelines take a lot of factors into consideration however, like the total length of stents, diameter, vessels stented, indication for stent, etc.

    1. Hi Peter, Dr. Sweitzer’s response is below. The article she says is attached can be found here: https://pubmed.ncbi.nlm.nih.gov/29544699/

      Thanks for sending this comment. I always appreciate when listeners engage and help me examine my beliefs and interpretation of the data/literature.

      I disagree that I conflated interruption of therapy with duration of therapy. And, I think the analogy with AC and AF is very apt. As I mentioned in the podcast the highest risk of thromboembolism with AF is within 30 days after cardioversion. The recommendations are to NOT discontinue AC during this period. After that the “risks” of discontinuation are nuanced and can be somewhat estimated by the CHA₂DS₂-VASc score. The guidelines recommend bridging AC for patients with higher scores.

      We know from non-surgical populations that pts with stents have variable risk of ischemia and stent thrombosis. Some of these risk factors are well known (e.g., stents placed for ACS, stents at bifurcations, under-sized stents, etc.) However, we don’t have a quantified “scoring” system (like CHA2DS2-VASc) to label pts with. But I do believe that’s why the recommendations are different for recommended DAPT for pts with stents placed for ACS vs stable disease. And, by inference one would suspect there is increased risk with interruption. And, the data clearly support this (I’ve attached just one article in support; there are more).

      Therefore, I stand behind my concerns that IF there is benefit of continuing DAPT for 12 m after PCI/stenting for ACS then is it truly optimal to d/c antiplt therapy for elective surgery (esp in an amb surgicenter) after just 6 months? Esp with evidence such as that presented in the attached manuscript. Let’s us not forget that discontinuing ASA is associated with a rebound hypercoagulability that peaks 7-10 days after d/c. Non-periop data suggest that up to 40% of ACS occurring in pts with known CAD (even w/o stents) may be attributable to d/c antiplts. Some pts are maintained on lifelong DAPT due to events occur when one drug was interrupted or to other high risk conditions. In fact, much of the decision around limiting DAPT has more to due with the increased risk of bleeding rather than the idea that the addn antiplt effect is unnecessary. So, it’s really a risk/benefit balancing.

      Lastly, below are direct quotes taken from the ACC/AHA DAPT guideline. I read this as not a ringing endorsement that it is “ok to stop DAPT after 6 m for surgery” but rather “its not unreasonable but still not w/o risk.”

      “On the basis of these considerations, the prior Class I recommendation that elective noncardiac surgery in patients treated with DES be delayed 1 year15 has been modified to “optimally at least 6 months.”” (pg e142) (quotes around “optimally at least 6 m” in the document itself)

      “Decisions about the timing of surgery and whether to discontinue DAPT after coronary stent implantation are best individualized. Such decisions involve weighing the particular surgical procedure and the risks of delaying the procedure, the risks of ischemia and stent thrombosis, and the risk and consequences of bleeding. Given the complexity of these considerations, decisions are best determined by a consensus of the surgeon, anesthesiologist, cardiologist, and patient.”

  2. Hi Dr. Sweitzer,

    Many thanks for your reply. I agree with you that these patients are at risk and interrupting DAPT at any point (even after 1 year) should be done with consideration. DAPT interruption seems to have become a topic of greater interest since we’ve started recommending life-long DAPT in select patients. So, to extrapolate your argument about patients who benefit from 1 year of DAPT… then it follows that the patients who need a lifetime of DAPT are also at risk if interrupted before prior to death.

    I agree the search for the safest time is ongoing, but the Canadian DAPT guidelines feel the data is compelling enough to suggest 3 months continuous DAPT is sufficient prior to interruption for elective surgery (1 month for BMS). This is based on PARIS data and a study published in The Lancet by Mehran in 2013. It suggests that interruption is quite safe after 3 months of continuous therapy. I think the US 6 month recommendations are likely based on Holcomb’s work from 2014 (https://www.sciencedirect.com/science/article/pii/S0735109714067515) that suggests a plateau by 6 months.

    I also agree we should be continuing ASA in all patients with an indication for it (i.e. secondary prevention). In Canada, there is disagreement on this point between the Canadian Cardiology Periop guidelines and the Canadian DAPT guidelines as one set relies heavily on the findings of POISE-2.

    I just bought your book on Amazon, by they way!

    1. Thanks. Dr. Sweitzer’s response:

      All good points. I don’t think we can ever reduce risk to zero. Therefore important to plan for “rescue” and be sure patients participate in decisions. Thanks for your interest in my book. Happy to hear feedback!

  3. Loved this episode! Very high yield. Can you post a link to the study that showed that a MAP of 65 was acceptable, instead of trying to keep people within 20% of baseline? Thank you!

    1. From Dr. Sweitzer:

      3 articles with links below:

      The first concluded that the associations of hypotension with AKI or myocardial injury based on relative MAP thresholds were no stronger than those based on absolute MAP thresholds. Furthermore, there was no clinically important interaction with preoperative pressure.

      The 2nd article is one that folks often refer to which “seemed” to support relative targets. However, the devils are in the details. This study compared individualized management which maintained a systolic blood pressure (SBP) within 10% of the patient’s resting SBP or what they termed “standard management” of treating SBP <80mmHg or lower than 40% from the baseline value. First problem was their use of SBP which is least important value for organ perfusion. And, second was the 10% target (traditionally we have used 15% or 20%) and lastly and most egregious was the VERY low value of a SBP of only 80 mmHg. Surprised JAMA even published this article.

      The 3rd article shows that preinduction MAP cannot be used as a surrogate for the normal daytime MAP.

      https://pubmed.ncbi.nlm.nih.gov/27792044/

      https://jamanetwork.com/journals/jama/fullarticle/2654895

      https://pubmed.ncbi.nlm.nih.gov/30998509/

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