Resident lecture on NAGMA

One hour lecture on NAGMA. Just some small changes edits from the last time I gave it. It is one of the few lectures that is still in PowerPoint. It is due for a complete overhaul. It also needs a slide on the treatment of RTA that covers the amount of bicarbonate in a 650 mg tablet (8 mmol) and the fact that distal (type 1) RTA requires a limited amount of bicarbonate (at most 1 mmol/kg). This is appropriate for residents and medical students.

If you are interested in ward teaching and RTA, take a look at this post by Robert Centor.

Also this is a nice article on the issue of saline having a pH of 5.5, covering both the reason (its the PVC bag) and the implications (none).


Student lecture on Acid-Base

I gave a lecture to the third-year medical students at Providence hospital on Friday. I thought the lecture went well but on saturday I was going over an admit note by one of the students in the class. The patient was admitted with DKA but had a combined metabolic acidosis and respiratory alkalosis. This student didn’t do the Winter’s formula calculation and missed the respiratory disease. Of course so did everyone else on the admitting team.


Here is the handout. I added a couple of things since giving the lecture on Friday.

Update: I corrected a mistake in one of the delta bicarb questions. Sorry.

Acid Base Handout (Student)

Fluid and Electrolyte lecture at Providence from Tuesday Dec 16

I did a lecture at Providence last week.

I was scheduled to just give a electrolyte lecture without any further guidance. I pulled out two interesting cases I had seen in the last few weeks. Both patients have a non-anion gap metabolic acidosis, but one is hypokalemic and the other is hyperkalemic.

Here is the native Powerpoint files for you to use or edit.

Here is the SlideShare for online viewing

Propofol induced lactic acidosis

I was consulted on a patient with acute renal failure and severe acidosis without an obvious source. The intensivist postulated this could be propofol induced B-type lactic acidosis. I had not previously encountered this entity.

Apparently propofol can block the electron transport train of the mitochondria causing lactic acidosis. Clinically the patients present with lactic acidosis, rhabdomyolysis and acute renal failure.

Propofol Infusion Syndrome Associated with Short-Term Large-Dose Infusion During Surgical Anesthesia in an Adult

Interesting article showing propofol decreasing oxygen utilization in animal model

Pediatric case in which the doctors captured increased levels of various types of carnitine indicative of altered mitochondrial oxygen utilization.

Craven et al found 24% rate of unexplained metabolic acidosis with propofol use, suggesting a much more common mild form of the disease.

My patient was exposed to only a single dose of propofol so I am skeptical but the lack of an alternative compelling etiology is leaving me considering this disease.

iPhone Medical Applications

I have four medical applications on my iPhone, of which I use two. Here is a quick review.

To show how the iPhone equipped physician approaches clinical problems I will use the DB’s Medical Rants most recent acid-base problem. He presents a case with the following information:

49-year-old man, previously in good health, presents after a few weeks of progressive weakness and dizziness. He admits to polyuria. Your job is to extensively discuss his lab tests.

The first step in my mind is to fully interpret the ABG. To do this we will use the application ABG.


This simply named program is an ABG calculator that runs through the standard algorithms for detecting multiple primary acid-base abnormalities. Can’t remember Winter’s Formula. As long as you don’t have boards coming up you can just plug’n chug and turn DB’s ABG into the following:

This does two of the calculations that DB describes at length:

  1. Winter’s formula (16 * 1.5 + 8 ±2) shows that the predicted pCO2 is 30-34. The patient’s CO2 is 33 so the patient has isolated and appropriately compensated pCO2 of 33. ABG displays this information in the second line when it describes the acid-base disorder as “Compensated metabolic acidosis.” It does not describe a second primary condition such as respiratory acidosis or alkalosis.
  2. Gap-Gap or delat-delta. The patient has a dramatically elevated anion gap at 27 (15 over the upper limit of normal of 12) but his bicarb of 16 is only 8 below normal. The difference between the delta gap and the delta anion gap is 7 (15-8) when this is added to the normal bicarbonate you get 31; so the patient had a pre-existing metabolic alkalosis with a bicarbonate of 31. ABG displays this information as the corrected bicarbonate.

The next step is adjusting his sodium for the hyperglycemia. To do this we will use Mediquations though Medical  Calc works just as well.

DB, in his discussion, states that he has unpublished data proving that no formula is effective at adjusting the serum sodium for the hyperglycemia. For those of us without his unpublished data should adjust the sodium using Katz’s traditional conversion (pdf of a letter to JAMA discussing adjusting sodium for hyperglycemia in DKA. Katz’s original conversion was discussed in a letter to the NEJM) of a drop in Na of 1.6 for every 100 the glucose is over 100 mg/dL. Nephrology fellows should additionally be aware of Hillier’s data showing the sodium falling 2.4 for every 100 of glucose. Both Mediquations and Medical calculator adjust the sodium using Katz’s conversion.

Of coarse you wouldn’t know it was Katz’s conversion because even if you tap on “More Info,” Mediquation does not provide the reference. Likewise you will not get the reference with Medical Calc.

Though DB did not explore free water defecits in his discussion of the case this is a clinically relevent point. You can use Mediquation to calculate the water deficit.

I feel that using ABG and Mediquations will make you a more effective physician without forcing you to memorize equations used only periodically.

Acid-Base lecture for ER residents

Yesterday I gave a great lecture on interpreting ABG results. I added a problems set for gap-gap analysis and added a section on the osmolar gap. I also improved the anion gap section with my new favorite nemonic. Forget PLUMSEEDS, forget MUDSLEEPS, forget MUDPILES. The new hotness is GOLD MARK:

  • M Methanol
  • A Aspirin
  • R Renal failure
  • K Ketoacidosis
This new nemonic was published in a letter in the Lancet (thanks vincent bourquin). I love that it drops the silliness of paraldehyde that no one uses anymore and drops isoniazid and iron which hardly ever cause an anion gap.
I also stumbled across a cool article on the sensitivity of the anion gap for lactic acidosis. Surprisingly an anion gap is only found in 58% of patients with an anion gap.
Additionally I cleaned up a bunch of the lecture. I still have not reformatted it for the iPhone so the handout is traditional 8.5×11 without a booklet form.

The Acid-Base lecture for the residents of St John Hospital

Today I gave my second lecture of the year for the St John Residency.

I used my Acid-Base workshop handout and added a slide show to facilitate the large group.

I still called on individual residents to answer questions to keep them involved.

I started the lecture with some audience participation. My previous lecture on IV Fluids, diuretics and dysnatremias began with me stating how ubiquitous these subjects were.

I had everyone stand then I asked people to sit down if, in the last three weeks they had not:

  • Used any diuretics: no one sat down
  • Used any IV diuretics: about half a dozen people sat down
  • Used a thiazide diuretic to counter the effect of loop diuretic resistance: lost a lot of people there but still had about a dozen left
  • Used a lasix drip to counter loop diuretic resistance from heart failure: everybody sat down but about 3 residents and the amazing Dr. Dhungel, my first year fellow on the consult service.
  • Used torsemide instead of furosemide for better pharmacokinetics: only Dr Dhungel remained standing.

I then tried to repeat the excercise for IV fluids and dysnatremias but it didn’t work very well. Should have quit after the first one.

When I gave that IV Fluids, diuretics and dysnatremias lecture I didn’t have a hand out. In the last three weeks I have worked up a handout:

iPhone version
Booklet form