Acid Base Disorders

A-a Gradient:  A-a (O2) = (FiO2%/100) * (Patm - 47 mmHg) - (PaCO2/0.8) - PaO2 (all units mmHg) http://www.medcalc.com/aagrad.html ACID-BASE DISORDER: Low HCO3: Metabolic Acidosis or respiratory alkalosis à ABG  High HCO3: respiratory acidosis or metabolic alkalosis à ABG  ACIDEMIA (pH<7.38): Metabolic Acidosis (HCO3- <22): Assess secondary respiratory response - Assess AG  NAG- Check UAG High AG (GOLD MARRK) (glycols [ethylene and propylene], 5-oxoproline [pyro-glutamic acid], l-lactate, d-lactate, methanol, aspirin, renal failure, rhabdomyolysis, and ketoacidosis) - Check Serum Osmolality, and  Assess Δ/Δ Gap Respiratory Acidosis (PaCO2 > 42): Assess secondary metabolic response and A-a gradient ALKALEMIA (pH > 7.42): Metabolic Alkalosis: Assess secondary respiratory response - Exogenous Alkali or Severe hypercalcemia  Chloride Responsive (Urine Cl < 25 ) Chloride Resistant (Urine Cl > 40), Assess Magnesium  Urine K < 20 Urine K > 30 BP High BP low or normal Respiratory Alkalosis (PaCO2 < 38): Assess secondary metabolic response and A-a gradient References: Lactate in Sepsis JAMA 2015 Electrolyte and Acid–Base Disturbances in Patients with Diabetes Mellitus NEJM 2015 Supplement to: Electrolyte and acid–base disturbances in patients with DM NEJM 2015 Acid–Base Problems in Diabetic Ketoacidosis NEJM 2015 Integration of Acid–Base and Electrolyte Disorders NEJM 2014 Integration of Acid–Base and Electrolyte Disorders (Supplement; NEJM 2014; Clinical Case Discussion) Physiological Approach to Assessment of Acid–Base Disturbances NEJM 2014 Physiological Approach to Assessment of Acid–Base Disorder Supplement NEJM 2014 (Clinical Case Discussion) Case 4-2015: A 49-Y-O-M with Obtundation Followed by Agitation and AGMA N Engl J Med 2014;371:1434-45.        N Engl J Med 2014;371:1434-45. N Engl J Med 2014;371:1434-45. N Engl J Med 2014;371:1434-45. Interpreting arterial blood gas results BMJ 2013 Lactic Acidosis  Lactic Acidosis NEJM 2014 Lactic Acidosis NEJM 2014 Lactic Acidosis NEJM 2014 Lactic Acidosis NEJM 2014 Lactic Acidosis NEJM 2014