Monday, August 29, 2016

Life Threatening Electrolytes




Slide deck (in pdf) for the above presentation:


Life threatening electrolyte abnormalities from Chew Keng Sheng


Perhaps one thing which I did not make clear in the video and the slide is the use of 3% hypertonic saline:
As 1g of Na = 17 mmol
therefore, 
3% NaCl means
3 g in 100 ml
or 
30 g in 1000 ml (1 L)
= (30 * 17) mmol in 1 L     [since 1 g NaCL = 17 mmol)
= 510 mmol/l 
~ 500 mmol per 1000 ml (1 L)
therefore, 
1 ml of 3% NaCL = 500/1000 = 0.5 mmol ------- Equation 1

Sodium deficit is
[Desired sodium - measured sodium] * Total Body water
= [Desired sodium - measured sodium] * 50% * Body weight (BW)

Now,
let say we wish to raise the serum sodium by 1 mmol/l  a.k.a. [Desired sodium - measured sodium ] = 1 mmol/l]

therefore,
[1*50%*BW] mmol/ = the amount of sodium deficit required

But we know from Equation 1, that 1 ml contains 0.5 mmol
therefore,
    0.5 mmol ------- 1 ml
    (0.5 * BW) mmol -------- (BW) ml

    Therefore, 1 ml per kg BW of 3% hypertonic saline raises serum sodium by 1 mmol/l

    However, as mentioned in the slide, the degree of serum sodium elevation may be more than expected. This is because as sodium is replaced, water re-absorption occurs initially. This removes the hypovolemic stimulus for the release of ADH. As a result, there will be greater degree of diuresis than expected.



    References:
    Parham WA, Mehdirad AA, Biermann KM, Fredman CS. Hyperkalemia revisited. Tex Heart Inst J. 2006;33(1):40-7. Can be accessed FREE here.


    Verbalis JG, Goldsmith SR, Greenberg A, Korzelius C, Schrier RW, Sterns RH, et al. Diagnosis, evaluation, and treatment of hyponatremia: expert panel recommendations. Am J Med. 2013;126(10 Suppl 1):S1-42. Can be accessed FREE here.







    Wednesday, July 27, 2016

    Discussion on the dilemma in bioethics using the various ethical theories




    We often discuss bioethical principles using Beauchamp and Childress (2008)'s four bioethical principles (some people would say that there are more than four) but seldom do we teach or guide students through some of these bioethical dilemma (which we often face in real clinical practice) using the various ethical or moral theories in philosophy.

    This short video starts with a case discussion follows by a short description of three common ethical theories. It's not meant to be a didactic tutorial but rather to trigger discussion among students.

    Case scenario:
    You are a house officer on duty. At 3.15 pm, you take some blood sample from a rather aggressive patient for some routine blood investigations that are due at 3 pm. Unfortunately, after you have taken the sample, you forget to label the sample bottles immediately. Worse still, one of the bottles drop on the floor and spill the sample. You would need to take a new 20-ml blood sample from this patient. You know that if you were to admit your blunder, he would ask you lots more questions than you can answer and furthermore, he is a hot-tempered man. You anticipate you will waste a lot of time with him and would result in delay in attending to other patients. Or you could lie to him and say that you need to do some additional blood tests that have just been ordered by your specialist (knowing that he would not question that). What would you do?







    Tuesday, May 03, 2016

    Spinal immobilization including cervical immobilization is no longer widely recommended for ALL trauma patients



    Spinal immobilization including cervical immobilization is no longer widely recommended for ALL trauma patients.

    In fact, the American College of Emergency Physicians (ACEP) has come out with a new statement that is against the use of long backboards by EMS (click here to access):
    “Backboards should not be used as a therapeutic intervention or as a precautionary measure either inside or outside the hospital or for inter-facility transfers.” 

    Backboards or spinal boards are transport devices, not immobilization devices. The spinal board is hard, but our spine has curvatures, and immobilizing them can aggravate spinal injuries on certain segments (besides risk of pressure sores, etc).

    The UK Faculty of Prehospital Care has also similarly discourages spinal immobilization. Click here: http://emj.bmj.com/content/30/12/1067.full.pdf+html 

    Spinal immobilization by itself is not harmless and has the following disadvantages:
    1. Time intensive to apply, thus delaying transport time to definitive care
    2. May create or aggravate ‘difficult airway’ scenarios
    3. Have been shown to increase mortality 2 fold in penetrating injuries (Haut et al 2010)
    4. Cause pressure ulcers
    5. Very uncomfortable, especially during transfers for X-rays, etc, increased length of stays in our departments.
    6. The cervical collar increases ICP because of decreased venous return due venous compression of the neck
    Read this article for better understanding:

    Prehospital Use of Cervical Collars in Trauma Patients: A Critical Review
    Available at:
    http://online.liebertpub.com/doi/abs/10.1089/neu.2013.3094

    Two podcasts you should listen to:
    1) http://foamcast.org/2015/04/02/episode-26-the-spinal-cord/
    (This one will give you a good review of differentiating spinal shock vs neurogenic shock, as well as different types of SCI)

    2) http://emergencymedicinecases.com/backboard-and-collar-nightmares-emergency-medicine-update-conference/

    Bottomline:
    1. An awake patient can probably protect his spine and back better than any of our gadgets can; and should be allowed to self-extricate and lie on the trolley.
    2. A patient who is not fully conscious or fulfill NEXUS criteria should have the neck immobilized - either with good fitting cervical collar or other means for manual stabilization (pillows, blankets).




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