Articles

Published on July 9th, 2013 | by Daniel Jolley

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The Cardiology Referral: Avoid hypoxia, avoid hypotension?

Recently I needed to refer a patient preoperatively to a cardiologist for review. This is not an uncommon situation — one which happens thousands of times every week throughout the world. And yet it is a referral that anesthesiologists and anesthetists often do very poorly.

Avoid hypoxia, avoid hypotension?

We sometimes roll our eyes at recommendations made by physician colleagues: either providing unhelpful physiological parameters that we normally aim to maintain anyway (“avoid hypoxia…”), or stepping outside their expertise and boxing the anesthetist in by suggesting specific anesthetic techniques (“okay for a spinal”).

It is easy to be annoyed at both the lack of value this adds to our perioperative planning, as well as to the nonchalant ignorance of intraoperative medicine that it betrays. At the end of the day though, it’s our fault.

As Dr Andrew Silvers, a Melbourne cardiac and neuro-anesthetist recently opined, if your cardiologist replies with “avoid hypoxia and avoid hypotension” then YOU the anesthetist or anesthesiologist are at fault for not asking your cardiology colleague specific questions that will materially effect your perioperative planning.

We are anesthetists and anesthesiologists who already understand how a patient’s intraoperative physiology can be best optimised and maintained. We appreciate the subtle benefits and costs of one anesthesia technique over another and can contextualize these costs and benefits for individual patients having specific surgery for specific indications.

What we need are answers to specific questions — and it is our responsibility to clearly ask for these, for example:

  • Is this chest pain / dyspnoea / vague-general-feeling-of-unease-whenever-I-watch-Project-Runway consistent with a cardiac cause?
  • Is there evidence of reversible cardiac ischema?
  • Is there evidence of systolic cardiac failure? Diastolic failure? Is it functionally significant?
  • Would this patient benefit from coronary revascularization?
  • Can they be further medically optimized?
  • What is the likely progress of their severe cardiac disease? Life expectancy? 1
  • Given it has only been 10 months since placement of a drug-eluting stent, and yet our patient has a need for major cancer surgery next week, we would like to stop clopidogrel for 7 days. Would bridging anti-platelet therapy be beneficial? 2

We should ask specific questions that we then use to contextualize our perioperative decisions — not ask (or allow) decisions to be made for us in areas in which we are the expert. The referral should also clearly explain the indication, timing and urgency of the surgery, particularly if the patient may undergo revascularization as a result of our referral. 3

Asking specific questions helps our cardiologists provide contextualized advice; it helps us conceptualize our perioperative planning needs; and most importantly it helps our patients receive the best perioperative care.

Ask yourself — what do I need to know to proceed with perioperative planning?

The funny thing about pre-anesthesia clinics

This leads nicely to a related area: the evidence for benefit of pre-operative anesthesia clinics.

While many anesthetists and anesthesiologists drag their feet if sent to staff a pre-anesthesia clinic, most would argue for its value — we like the idea of our patients having been through the clinic, many just don’t want to be the clinic anesthetist themselves!

The actual evidence is surprisingly non-supportive. I will explore the evidence for pre-anesthesia clinics in a future article.

Notes:

  1. Severe coronary and cardiac disease often has 2 year survival rates worse than many primary cancers! Estimates of life expectancy help to contextualize the appropriateness of surgical intervention: eg. asymptomatic hernia repair is likely not appropriate for someone with NYHA-IV cardiac failure on maximal medical therapy.
  2. Probably not! There is limited evidence of benefit for bridging therapy. Incidentally, the evidence for benefit in continuing DAPT (dual anti-platelet therapy) to 12 months rather than temporarily stopping for 7 days at, for example, 10 months is only suggestive. The limited evidence that has looked at these scenarios has been inconsistent and not conclusively shown harm from non-bridging cover of temporary cessation. As in all things, these need to be looked at on a case by case scenario in consultant with the patient’s cardiologist.
  3. To assist our cardiologist with deciding plain-old balloon angioplasty (POBA), bare-metal stent (BMS) or drug-eluting stent (DES), each having different anti-platelet therapy needs.

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About the Author

is an Australian consultant anaesthetist/anesthesiologist, with interests in anaesthesia education, obstetric and paediatric anaesthesia, and the practice of anaesthesia in remote and under-resourced environments. Daniel trained in Sydney, Darwin and Melbourne, and has worked in Sydney, Melbourne, Darwin, Fiji and Mongolia. He is one of the founders of gasexchange.com along with Brad O’Connor.


One Response to The Cardiology Referral: Avoid hypoxia, avoid hypotension?

  1. sam.lumb says:

    Excellent point, as a registrar it’s easy to forget the clear benefits that sometimes can be found in a good pre-anaesthetic clinic and good advice for approaching other specialties with more appropriate advice.

    I often wonder how other people approach and run their clinic visits and how differently from mine it would be. The other problem is that you don’t, the vast majority of the time, anaesthetise the patients you see in clinic, and thinking ahead to make sure you do what the person on the day wants, and to try satisfy a massive range of expectations.

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Notes:

  1. Severe coronary and cardiac disease often has 2 year survival rates worse than many primary cancers! Estimates of life expectancy help to contextualize the appropriateness of surgical intervention: eg. asymptomatic hernia repair is likely not appropriate for someone with NYHA-IV cardiac failure on maximal medical therapy.
  2. Probably not! There is limited evidence of benefit for bridging therapy. Incidentally, the evidence for benefit in continuing DAPT (dual anti-platelet therapy) to 12 months rather than temporarily stopping for 7 days at, for example, 10 months is only suggestive. The limited evidence that has looked at these scenarios has been inconsistent and not conclusively shown harm from non-bridging cover of temporary cessation. As in all things, these need to be looked at on a case by case scenario in consultant with the patient’s cardiologist.
  3. To assist our cardiologist with deciding plain-old balloon angioplasty (POBA), bare-metal stent (BMS) or drug-eluting stent (DES), each having different anti-platelet therapy needs.
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