Approach to Metabolic Acidosis | Non-AG Metabolic Acidosis

This Emergency Medicine video gives a rundown on the high-yield points of the clinical approach to metabolic acidosis that will help you prepare for your exam. This is the most complex disorder because it has a lot of causes, and they are split into two main groups: anion gap and non-anion gap metabolic acidosis. Before we get into this video make sure you watch our previous video on acid-base disorders approach to have a better idea of what we’re discussing in today’s video. Let’s review the four main types of acid-base disorders that can occur, which are: 🔹Metabolic Acidosis 🔹Metabolic Alkalosis 🔹Respiratory Acidosis 🔹Respiratory Alkalosis In this video we’re talking about Metabolic Acidosis specifically, so let’s start learning. ▬ 📌 Chem 7 - Fish Bone Diagram Chem 7 Fishbone diagram is usually used by house officers in the ward, to write down the lab values to calculate the anion gap. The values we need for calculating the anion gap are Na+, Cl-, and HCO3-. ▬ 📌 What is an Anion Gap? The anion gap is the difference between the positive ions (cations) and negative ions (anions). To diagnose the metabolic disorder, we calculate the anion gap in the blood plasma. To calculate the anion gap, we take Na+ from chem 7 minus the Cl- ions and the HCO3-. Now out of all the other ions that contribute and are not included in the Chem 7, the anion albumin which is a protein is most responsible for contributing to the anion gap, so it’s important to note here that a low anion gap can be caused by hypoalbuminemia. Since it results in the retention of other negatively charged ions such as chloride and bicarbonate. ▬ 📌 Importance Of Anion Gap Measurement of anion gap in the plasma divides the causes of metabolic acidosis into two groups: 👉 Metabolic acidosis with a normal anion gap - this results in acidosis due to loss of bicarbonate ions (HCO3-) 👉 Metabolic acidosis with an increased anion gap - metabolic acidosis is from the retention of acid Watch the lecture to learn which ions increase and decrease in the body to cause these metabolic conditions, especially mentioning hyperchloremic metabolic acidosis. ▬ 📌 Metabolic Acidosis Formulas Now, let’s look at some special formulas we use for metabolic acidosis. 👉 Winters Formula -This is used to determine whether the respiratory compensation for metabolic acidosis is appropriate or not. and we have discussed this in our previous video as well. (used to assess secondary respiratory disorder.) 👉 Delta-Delta Ratio- This formula is used in Anion gap metabolic acidosis (used to assess secondary acid-base disorder) ▬ 📌 Non-Anion Gap Metabolic Acidosis Causes Now that we have established there are two main types of metabolic acidosis, we’re talking about the causes of non-anion gap metabolic acidosis. So, there are 6 main causes of non-anion gap metabolic acidosis. This is commonly remembered by the mnemonic: “HARD ASS” 🔹Hyperalimentation - which is receiving IV nutrition, this causes for a lowered pH 🔹Addison’s Disease - in this disease there is a loss of aldosterone effect, therefore the inability to secrete hydrogen ions causes acidosis. 🔹Renal Tubular Acidosis - also causes metabolic acidosis and we’ll talk about this a little more in a separate video. 🔹Diarrhea - this causes bicarbonate ions to be lost in the stool and therefore causes acidosis. 🔹Acetazolamide - this blocks the formation and resorption of bicarbonate ions in the proximal tubule, so you lose more bicarbonate ions 🔹Spironolactone - this is an aldosterone blocker; and again, because you cannot secrete H+ effectively, this is retained, and acidosis develops 🔹Saline Infusion - you decrease the Renin angiotensin aldosterone activity which lowers the aldosterone levels, and you retain H+ ions causing for acidosis. ▬ 📌 Anion Gap Metabolic Acidosis Moving on to the metabolic acidosis caused by an anion gap now. We have an easy way to remember this is by the mnemonic: “GOLDMARK” 📍G → Glycols (Ethylene glycol, propylene glycol) 📍O → Oxoproline (Toxic metabolite of acetaminophen) 📍L → L-Lactate (Lactic acidosis) 📍D → D-Lactate (exogenous lactic acid) 📍M → Methanol (and other alcohols) 📍A → Aspirin (late effect) 📍R → Renal failure 📍K → Ketones (diabetic ketoacidosis, alcoholic, starvation) So, basically the loss of something that is other than Chloride ions and not in the anion gap calculation formula. I hope you guys enjoyed this video and keep a look out for the next one! ▬ 🎬 5500+ sqadia.com Medical Videos ▬▬▬▬▬▬▬▬▬▬ 👩🏻‍⚕️ Accessible Medical Student Education 24/7/365 💡 Simplifying Medical Learning 💪 Study Hard, Dream Big, Achieve More