ACLS : Bradycardia Differentials

5 04 2021

Differentials for Bradycardia

I am a little biased towards figuring out if the patient had a STEMI or if they are hyperkalemic because those are likely to be immediately life threatening and have drastically different management. Trying to manage Hyperkalemia induced bradycardia with ACLS drugs is not so effective. Hence my most high yield bedside investigations are an Electrocardiogram and point of care potassium (draw carefully to avoid hemolysis)

  1. Cardiac – Sinus node or AV node dysfunction from various etiologies (including STEMI, myocarditis, post-surgery)
  2. Hyperkalemia – most often in ESRF with missed dialysis, but also in acutely ill patients (eg severe dehydration, shock with Acute Kidney Injury)
  3. Drugs – multitude of drugs especially cardiac ones such as beta blockers, Calcium channel blockers, Digoxin, Opioids, Sodium channel blockers. Consider illict drugs and poisonings such as Organophosphate
  4. Neurological causes – raised intracranial pressure (evolving towards a Cushing’s Triad), Neurogenic Shock (taking out the sympathetic drive)
  5. Others – Hypothyroidism, Hypothermia, Hypoxia
  6. Infectious diseases – typhoid etc (not common in Singapore) especially if disproportionate to fever
  7. Periarrest – any critically ill patient can decompensate and become suddenly bradycardic.

Some other causes to consider

  1. Conditioning – athletes with high vagal tone, many know their resting heart rates
  2. Vagal response – to pain, emotional distress – recovers within minutes

Always consider and investigate the most critical causes first before suggesting a benign cause.


  1. emDOCS – An Approach to Bradycardia in the Emergency Department
  2. Circulation – Part 7.3: Management of Symptomatic Bradycardia and Tachycardia

ACLS : Transcutaneous Pacing

6 02 2021

Pacing 101.

  1. Sedation and analgesia.
    My personal preference is a combination of fentanyl and midazolam. If your patient is awake – briefly explain the procedure to them and get their consent if possible.
  2. Use the pads.
    The paddles are going to be harder to hold. Make sure that the pads and the 3 leads are via the same machine. If your bay/bed has a monitor + defibrillator and you separate the monitoring and pacing – it won’t work. Also prep the chest for appropriate contact – clip excess hair (avoid shaving), wipe off excess fluids, move jewelry aside, keep medical devices away and remove any drug patches. Anterior Posterior position is preferred.
  3. Switch to pacing mode and choose fixed.
    I cannot find any sources mentioning which mode is superior. Demand mode is useful if the patient has an intermittent perfusing rhythm, in the ED we often just use fixed mode. The pacing mode is also sensitive to good sensing eg if there’s artifacts because of poor contact with the pads, this might go haywire.
  4. Set a rate.
    I like to use 60-80bpm.
  5. Set an output.
    The sicker your patient, the higher you want to start, you can do 70-80 mA and adjust accordingly. Aim to be 10-20 mA above the minimum to maintain that pacing (eg if the patient moves and there’s poor contact etc)
  6. Check for capture.
    This should be both electrical (a pacing spike is consistently followed by a waveform) as well as mechanical (a consistent pulse is felt – preferably distally to avoid the confusion from the muscle twitch, as well as an improvement in the hemodynamics)
  7. Call your friendly cardiologist.
    The patient may need to be on transvenous pacing, an urgent angiography / angioplasty or even a permanent pacemaker. Most of these patients need to be in a cardio High Dependency or Intensive Care Unit anyway.

Further Reading :

Physio-Control Manual on Non-invasive Pacing

Internet Book of Critical Care – Bradycardia

Experiment Number 2 in Cold Brew Coffee

5 04 2015
I first got into cold brewing after a visit to a tea shop in Hong Kong which suggested I could drench my tea leaves in cold water to let them soak before dunking them into hot water. I liked the flavour that produced and my further online reaearch suggested that I could actually go all the way and cold brew tea by soaking tea leaves in a cup overnight in a fridge. That produced a perfect flavour profile (strong, but just short of acidic) for a tea I got from Taiwan. It was convenient too, because I could leave it in the fridge for a couple of hours and drink it,  without having to pay attention to how long I was brewing it while heating the water.
I tried the cold brew experiment a month or two back with a bag of ground coffee from Highlander. I watched a couple of youtube videos, including the one on Jamie Oliver’s channel. I emptied an entire 250g of ground beans into the jar and topped it up with abotu 750 mls of water. I let the jar sit in the fridge overnight before the excruciating process of filtering the ground from the finished product. I used multiple Boncafe’s filters (the 4-6 cups one)  for the entire batch and ended up with a strong concoction (which, not knowing how to dilute, left me jumpy and tachycardic for the evening) it did keep me up for an entire night of partying though. What’s bothered me so far is how the cold brew (or anything short of a properly, foamy latte) lacks a kind of fullness to the sip, but I’ve given up trying to achieve that.
This time round, I decided to try it again, with the intention of using the coffee concentrate for something else. I used about 100gm of coffee power (Kaffe Kaldi’s French Roast) in around 800mls of water. Let it soak for 24 hours and filtered it out (nothing fancy, just a strainer and 6 pieces of filter funnels, consecutively) to come up with the final product that you see on my instagram. The difference between this batch and the previous one, I recall specifically that the KK grounds sank to the bottom while the Highlander ones were mostly floating on the surface. Again, since I do not recall the previous flavour profile, I can’t say for sure how that might have affected the taste.
Co-incidentally, Coffee:Nowhere was hosting a little fair at West Coast Plaza and had some of their cold brews for sale, so  I decided to buy a bottle for comparison’s sake. I cannot recall how my previous batch tasted like and I’m not the connoisseur to differentiate the subtle notes (apple, cinnamon, freshly cut rubber hose), there was something definitely different. My coffee had some bitter notes that were upfront lasted throughout. The bottled coffee (“Specialty Blend”, but no other details) had a gentler, smooth acidic note to it.
I’m not sure if cold brew is a hugely different beast from hot brew, because I have never made my own hot brew at home from grounds and when I’m buying some outside, I never have it black, nonetheless, having two samples to compare, the bottled once had actual flavour beyond the acidic note, while mine didn’t. I noticed the colours looked different, so I diluted mine a little and it toned down the bitter, but had basically, very little flavour otherwise. In retrospect, I should probably consider using the full 200g next time.
What am I going to do with my home made jar of cold brew coffee? Follow me on Instagram @csjjjj and see for yourself tomorrow.

I found the tenses on this govt FAQ a little odd

18 02 2014

I was taking a break from studying by browsing the FAQs for MediSave which is a fund set up by the government where you contribute a bit of your salary to so as to help cover medical bills. Here’s what I saw.

medisave tenses


Read the rest of the FAQ  here.

Every Pre-Med should read this

15 10 2013

While at the infinity pool at school, I had this discussion with my friend about what the philosophical basis of Medicine is. What exactly is Disease and how do or can we know for sure? There are no easy answers to that, though I get the inclination that the boundaries of the question and the lenses we use to look at it, change slightly depending on the problem at hand. I went around looking for answers and discovered that there is an entire field called the Philosophy of Medicine. I bumped into an article at the Internet Encyclopedia of Medicine discussing these perspectives. I felt that it gives a good overview on the theory and practise of Medicine and the fact that I am now more familiar with the subject, it is easier to understand the philosophical jargon. I feel that the article gave me a better philosophical foundation to understand both the evolution of ideas in Medicine and added some colour and structure to thinking about the field. I’m planning to read around the subject, with more content to come!

Happy Nurses Day and a bit about Nightingale

31 07 2013

The week long celebration started on Monday. I haven’t been to the hospital the entire week, so I’m not entirely sure what is going on there nor have I been able to have a heart to heart talk with my nursing friends and colleagues.

I noticed, when I was in India, that they celebrate theirs on the 20th of May which is the birthday of Florence Nightingale. Although we grew up with the image of her as a self-sacrificial figure in the care of fallen soldiers, she was much more than that.

As an educated, empowered woman, she is, to an extent a feminist symbol for rejecting the suffocating expectations placed on an upper-class woman to be a baby-making machine. Instead, she decided to be a nurse, against the wishes of her her family. She was also known to travel widely and work with politicians, write extensively and do big-picture planning.

It is also easy to forget her role as a pioneer of the hospital  as a well organised system. Her experience in the Crimean War showed that many soldiers were dying from diseases apart from the battle injuries. She seems, from my reading of her Wikipedia entry, to be an early adopter of some sort of Evidence Based Medicine. Which, to put simply, is the use of scientific methods to understand if your treatment is working and to tease out the risks of it. Her background in statistics probably helped and she actually compiled data on her patients as opposed to basing her ideas on “experience”. The patterns she observed from this eventually led her to place great emphasis on sanitation.

The next time the ward sister reminds you the clean your hands in the MRSA ward, it’s Florence Nightingale speaking through her 😉

On a more personal note, although Nurses play a great variety of roles, my experience of them has largely been as “guardians”. Watching our backs, administering treatment, actually caring for patients, apart from merely treating them. Often, they take the brunt of the aggression from angry patients.

As a friend of mine often points out, I do wonder if they are under-appreciated by physicians, although there have been a lot of hints that the system could do better in taking care of them. Perhaps it is time to reconsider how nurses are remunerated? Maybe there is a need to clearly define, or perhaps redefine nursing? I do not know what the future holds and I don’t have immediate ideas. Nonetheless, I am greatly indebted to those nurses I have had to privilege to work with, both personally and professionally.

Happy Nurses Day!


And here is a picture of Nurses going on strike in Singapore in the 60s. It is still on the wall at SGH, I think 😛 Not that I am encouraging you to go on strike (we will all die), just that I have faith in the community to be resourceful and make bold reforms.

Nurses on Strike!

Perspective I

19 07 2013

While I was trying to channel my anger into something constructive, I ran into a bunch of pictures in a feature by FSTOPPERS on Tom Hussey’s Reflections. It’s an eye opening look at the elderly staring back at a reflection of their younger selves. Hussey has a great portfolio on his website and you can see the entire collection here.

This something I ponder about a fair bit, in conjunction with reflections on Death, partly because that seems to be the next stage.  I’m surrounded by the elderly at work, so I am rather surprised/ashamed that I haven’t had the Old Age and Death conversation with anyone. Perhaps it’s the language barrier, perhaps I’m just caught up with the routine. I’ll do that the next time I see someone who might be willing.

That’s probably me in 40+years. If I live that long.



Next time you see “Revolutionary New Cure for Cancer”

28 05 2013


XKCD Does it again. I do wonder if webcomics are the future to public health. Though this post deserves some explanation with examples in the future.

vodka grapefruit!

28 04 2013

I wonder a lot and I don’t always find answers to my questions, but when I do, it’s fabulous 🙂

Caveat: Ain’t encouragin’ no drinkin’ here. Photo by Vikingfjord US

This is a story of how a bunch of researchers discovered the wonders of Grapefruit. All medics know that grapefruit juice has certain compounds which affect how the body processes certain drugs. I took that for granted until one fine day, I asked myself, “How did they figure that out?”. Did doctors, while taking a history of a patient with some trouble with their drugs, ask if they had soy sauce, maple syrup on their waffles or grapefruit juice for breakfast? Did they then do the same thing with other patients with similar problems and see a pattern? I have rarely heard a physician go into that much detail about diet so I doubted that explanation. I looked up the literature (kidding, I just googled it) and uncovered an interesting story.

Sometime, either in the late 80s or early 90s, David Bailey and his team of Canadian researchers were doing experiments to see if consuming alcohol together with the blood pressure drug felodipine made any difference to the drug’s effectiveness. The participants were split into two groups, one was given alcohol plus the drug, and one, just the drug. To avoid the placebo effect, the experiment needed to be conducted in such a way that the subjects did not know whether they were having alcohol or not.  Turns out one way to do this is to use a mixer. Specifically grapefruit juice, the sharp taste of which would mask the taste of alcohol. When they ran tests on the levels of drug in the subjects’ blood, they found out that the drug levels were way higher than expected, even in the grapefruit juice group.  And that friends, is how we discovered the effects of grapefruit juice.

It turns out that pomelo and lime juice can also affect drug processing, while orange juice seems safe.

Of Logos and Evidence Based Medicine

22 11 2012

One of my friends was on exchange and I noticed a logo on the said friend’s facebook profile.

Looks familiar?

It kind of resembled my own school’s medical society logo.

NUS MedSoc Logo

I recall, back in my first year, we had a short lecture on the history of medicine and the lecturer briefly spoke about the logo, with an amused look. Apparently there is a bit of confusion with regards to the symbol and strictly speaking, the Stockholm school uses it the way it should be, based on its roots.

The winged rod with two intertwined snakes is actually the Staff of Hermes (Mercury in Roman Mythology), known as the Caduceus. Some historians interpret it to symbolise “balanced exchange and reciprocity” which are values which drive commerce. Since Mercury is the “the messenger of the gods, guide of the dead and protector of merchants, shepherds, gamblers, liars, and thieves” this has come to symbolise all these aspects. It’s often erroneously used by Medical Societies, especially the commercial ones, and this can be traced to it’s adoption as the symbol of the US Medical Corps in 1902. Wikipedia covers this in more detail in a very readable fashion.

The actual symbol representing Medicine, based on Greek mythology, is the Rod of Asclepius, the god of healing and it comprises a single snake twined around a rod, as below.

The Actual Rod of Healing


After a lecture today though, I think the (misused) logo can potentially be re-interpreted in the light of Evidence Based Medicine (EBM).

Simply put, EBM is an approach where we use evidence to analyse treatments (and lab tests, physical exam techniques etc) to objectively figure out whether our treatments (or tests) actually work. This might seem like a mundane question to those outside of the field, because, if someone takes a pill and gets better, a treatment works right? The reality is a little bit more complicated than that. As a counter to that, I might ask, how do you know that the pill made someone better? They might have gotten better anyway in a few days. In addition to this, for long term illness, one sometimes has good days and bad ones.  With this in mind, researchers (who are often Medical Doctors, but this can involve people from various healthcare fields) design studies to tease out the various factors so at the end of it, one can be confident that the treatment is effective.

An extra element of complexity is added when we consider the fact that certain treatments can be potentially harmful. Drugs sometimes have side effects or may have dramatic effects which can cause harm under various circumstances. An example is the use of “blood thinners” to prevention ischemic strokes due to blood clots choking the blood supply to the brain. Blood clotting (or coagulation) is a chemical reaction where proteins in the blood clump together with cells to form a clot. The clotting of blood is important to prevent bleeding but in diseases of the blood vessels, there is an increased tendency for blood to form a clot and block blood vessels.  Blood thinners, or more accurately, anti-coagulants, impair this process. They don’t actually make the blood thinner. However,  in a legitimate bleed, you still do want the blood to solidify and cause the bleeding to stop. A consequence of blood thinners is that the bleeding may not stop in the event of an injury.

With this in mind, it is imperative that Doctors use research and figure out how to balance the risk of an uncontrolled bleed versus the risk of a stroke in diseases of the blood vessels. Part of this strategy is to use the right drugs (some are weaker and hence less likely to cause bleeding) and to understand the patient and disease better (those with severe disease may still need stronger drugs). These days, there is a cost element that doctors need to be aware of, and we also know that the more complex a treatment, the less likely patients are to accept it and it may be more difficult to follow it. What this means is that our role has become more complex and we need to “balance and negotiate” a multitude of factors when we treat people.

If you dig around a little, there is this uncanny symbolism to the myths and paraphernalia associated with Hermes. A publisher used the staff as an emblem with a biblical quote reminding one to “be ye therefore wise as serpents, and harmless as doves.” Seems a lot like an exhortation to be a critical thinker but to balance it with empathy for patients. Hermes is also the “messenger of the Gods” and seen as a guide. Doctors are often looked up as people who “know the science” and there is a huge expectation upon us to be able to communicate this to patients, to help work with them to tailor their treatment. He is seen as swift and cunning and a navigator, and people expect us to be on their side when it comes to navigating the vast an complicated realm of healthcare.

I smugly laughed back in my first year when the lecturer potentially interpreted the Medical Society’s logo as representing the “commercialisation” of medicine. However, knowing this background it seems amusingly appropriate.

And the bit about Hermes as the god of Gamblers? Here’s a quote from the Oxford Handbook of Clinical Medicine (aka the Medical student’s pocket bible).

“Rather, medicine is for gamblers. Gamblers who use subtle clues to change their outlook from pessimism to optimism and vice versa”