Base Treatment for Metabolic Acidosis due to DKA and Sepsis
Nicholas Busch Henry Ford Hospital Emergency Medicine Grand Rounds September 17th, 2015 So who should get an AMP or two?
24 yo male with DKA pH 6.90 pCO2 45 HCO3 8 So who should get an AMP or two?
65 yo with septic shock pH 7.10 pCO2 42 HCO3 10 Objectives Quick Acid-Base review
Discuss the hemodynamic effects of base therapy Discuss evidence for base therapy in: DKA Lactic acidosis/sepsis Not covered: Pediatrics, respiratory acidosis, toxic ingestions, RTA and other non-AG acidosis WHY? WhO? Who gives sodium bicarb therapy?
About 100 surveys completed by critical care and nephrology program directors throughout the nation. Patients with lactic acidosis
-67% of critical care physicians -86% of nephrologists Patients with ketoacidosis -28% of critical care physicians -60% of nephrologists VERY Quick Acid-Base Review
CO2 + H20 H2CO3 HCO3 + H+ Henderson Hasselbalch pK curve Using white board Also whats an AMP?? Ampule (amp, ampoule)
NOT standardized unit of measure Single dose of medication pre-packaged in an injectable glass or plastic vessel An amp of Bicarb 8.4% Sodium Bicarbonate 50 mEq Na+, 50 mEq HCO3-
pH 8.0 1 mL is 84 mg Framing the Question Proposed Rationale for Base Therapy Use:
1. A low pH, in and of itself, is harmful (most notably by impairing cardiovascular function). 2. Sodium bicarbonate can increase the pH when infused IV. 3. Raising the pH with sodium bicarbonate improves cardiovascular function or some other relevant outcome. 4. Any adverse effects of sodium bicarbonate are outweighed by its benefits A low pH, in and of itself, is harmful (most notably by impairing cardiovascular function)
-Isolated animal heart muscle - acidosis generally reduces contractile function Human ventricular tissue showed modest reduction in contractility Whole animal models: contractility constant, decrease slightly or rise and then fall ARDS treatment : permissive hypercapnia tolerated to 7.15 and below Protective effect? reduced cell death in hepatocytes exposed to anoxia Sodium bicarbonate can increase the pH when infused IV
Most animal studies show arterial pH will rise What about the intracellular pH?
Multiple compartments with different degrees of permeability Cerebral spinal fluid Bicarb shown in dog models to LOWER CSF pH Intracellular Space Raising the pH with sodium bicarbonate improves cardiovascular function or some other relevant outcome 2 studies in humans with lactic acidosis and getting continuous vasoactive infusions No change in hemodynamics or catecholamine responsiveness HR, CVP, PAP, ScVo2, wedge pressure, or CO Still negative results with most acidotic ( ) Any adverse effects of sodium bicarbonate are outweighed by its benefits
Negative side effects Fluid and sodium overload Lowers pO2 and oxygen delivery Increased lactate concentrations Lowers calcium LV contractility varies directly with ionized calcium concentration Clinical significance has not been demonstrated More direct question Does Sodium Bicarbonate improve outcomes for patients with severe DKA or lactic acidosis from sepsis? DKA 24 patients received 120+/-40 mmol sodium bicarbonate.
Two groups were similar at admission with regard to clinical and biological parameters Prospective, randomized trial No difference could be demonstrated between the two groups - 21 adult patients, DKA with pH 6.9 to 7.14
No significant differences in Glucose or ketone levels Increase in pH orHCO3 in blood or CSF Time to glucose 250, pH 7.3, bicarb to 15 We conclude that in severe diabetic ketoacidosis (arterial pH 6
We conclude that in severe diabetic ketoacidosis (arterial pH 6.9 to 7.14), the administration of bicarbonate does not affect recovery outcome variables as compared with those in a control group. No Significant Difference: Hospitalization Mortality
12 case control studies 3 RCT with 73 patients No Significant Difference: Hospitalization Mortality No studies had any patients with pH