Base deficit calculation

Background Base deficit (BD) is commonly used in the operating room (OR) as an endpoint of resuscitation. BD is used as a surrogate marker for the accumulation of lactic acid(Lac). However, the BD can be affected by large amounts of saline. Methods We conducted a survey of anesthesiologists regarding the use of BD. We also studied the reliability of BD to determine the presence of hyperlactatemia (HL). Patients undergoing general anesthesia were eligible for enrollment if they were receiving an arterial line as part of their routine care. If an arterial blood gas was drawn by the operative team as part of the routine care, the remainder of the unused blood was also used to measure Lac. Results Survey: 73 staff anesthesiologists were surveyed. Over 70% of respondents used BD as an endpoint of resuscitation. Base Deficit Study: 35 patients were enrolled resulting in 88 arterial blood gases with corresponding Lac. Mean age was 61.4 ± 14.3 years, 43% were male. Mean pH was 7.39 ± 0.05, the mean bicarbonate was 23.0 ± 2.3 meq/L, the mean BD 1.34 ± 2.3, and the mean Lac was 1.58 ± 0.71 mmol/L. Mean ASA risk score was 3.16 ± 0.71. ROC area under the curve for base deficit to detect HL was 0.58. Conclusion BD can often mislead the clinician as to the actual Lac. Lac can now be measured in the OR in real time. Therefore, if clinicians in the operative setting want to know the Lac, it should be measured directly. Full size image Base Deficit Study This part of the study was co...

Sodium Bicarbonate Deficit Calculator Inputs Height: Weight: Select Volume of distribution (VD) factor: Select Dosing Weight: Select current HCO 3 - Level: Select desired or target HCO 3 - Level: Background: In all cases, the primary goal in treating metabolic acidosis is to focus on reversal of the underlying process causing the acidosis. Examples: (1) Renal failure: dialysis if needed. (2) Alcoholic ketoacidosis: fluids, electrolytes, thiamine, folic acid. (3) Sepsis/shock: volume resuscitation, vasopressors, etc. (4) Salicylate intoxication: IV fluids, alkalinization of the urine, .... If there is a severe deficit (HCO 3- Greater increases in bicarb Vd ---> Larger amounts of bicarb must be administered. 2] Following admin of bicarb (as a bolus), there is a time-dependent decrease in blood HCO3- conc. A portion of the HCO3- which is initially distributed in the ECF space, subsequently enters the intracellular space. 3] As the blood HCO3- concentration increases, the PCO2 increases as a result of a decrease in alveolar ventilation. Reference: Ewald G, McKenzie C (editors). Manual of Medical Therapeutics, 28th edition. Little, Brown and Company. 1995. page 59 and 63. Since the distribution of bicarbonate is about 50% of lean body weight, ... serum concentration to normal can be estimated as follows: HCO3~ deficit (mEq) = 0.5 x lean body wt (kg) x (desired [HCO3-] - measured [HCO3-]) Lean body weight defined as usual IBW equations: Estimated ideal body weight in (kg): Male...

Contents • 1 Background • 2 Components • 2.1 pH • 2.2 P vO 2 • 2.3 P vCO 2 • 2.4 HCO 3 • 2.5 Base Excess • 3 Comparison with ABG • 3.1 Disadvantages • 3.2 Advantages • 4 External Links • 5 References Background The venous blood gas ( VBG) is a multi-component serum assessment of pH, blood gas tensions (P vO 2 and P vCO 2), bicarbonate (HCO 3), and the base excess. • can be drawn from an IV catheter along with other bloodwork, unlike an arterial blood gas ( • does not accurately reflect (P aO 2) • arterial values of pH, CO 2, and HCO 3 can be extrapolated with varying levels of accuracy Components pH • measurement of acidity/alkalinity: normal range 7.37-7.45 • pH > 7.45 = alkalosis • pH45 = primary respiratory acidosis • P vCO 245; authors suggest that P vCO 2 can be used to screen for hypercapnea • metaanalysis shows 95% prediction interval P vCO 2 of -10.7 mm Hg to +2.4 mm Hg Advantages • convenience • no extra, painful radial artery access to draw ABG • can be easily obtained with IV access • pH very reliable • some studies do show • in the era of continuous pulse ox, meaningful information about oxygenation is always available • the P vCO 2 is internally consistent • can trend CO 2 response to treatment; just don't know exact starting point External Links References • Byrne AL, Bennett M, Chatterji R, Symons R, Pace NL, Thomas PS. Peripheral venous and arterial blood gas analysis in adults: are they comparable? A systematic review and meta-analysis. Respirology. 2014 F...

getting started: metabolic vs. respiratory abnormalities metabolic vs. respiratory pH disorders • Metabolic disorders involve a primary change in the serum bicarbonate and/or anion gap. • Respiratory disorders involve primary changes in the pCO2 (due to changes in CO2 removal by the lungs). ABG/VBG isn't needed to evaluate metabolic pH disorders • Complete analysis of pH status requires blood gas analysis, but all you need to determine the metabolic pH disorders is an electrolyte panel. • Analysis of the metabolic pH disorders is usually the most important component (and frequently sufficient to guide treatment). • Metabolic pH analysis should be performed on every set of electrolytes obtained from every patient. Additional evaluation with ABG/VBG may be performed more selectively. the anion gap basic properties of the anion gap • Anion Gap (AG) = Na – Bicarb – Chloride • A normal anion gap is roughly 4-12 mM. • Historically, the normal range of anion gap was often quoted as being higher (e.g. up to ~16 mM). However, with newer electrolyte analyzers, the upper limit of normal has decreased to ~11-12 mM. ( • Comparison with a baseline anion gap might be helpful, if that is available. For example, a patient with chronic renal insufficiency may have a chronically elevated anion gap at 14 mM. If this represents no change from previous labs, it is less likely to represent an acute and dangerous process. you don't need to correct for albumin • Albumin is a negatively charged pro...

Before You Begin: Gather Data What lab tests do you need? • ABG vs. VBG • VBG can provide reliable estimation for pH (0.02-0.04 lower than ABG) and HCO3 (1-2 mEq higher than ABG). • pCO2 on VBG is higher than arterial PaO2 by 4-9mmHg. • ABG is necessary to accurately assess PaCO2 in hypercapnia or severe shock. • Basic metabolic panel. • Albumin. • See specific acid-base disturbances for other helpful testing. Step 1: Determine Primary Acid-Base Disturbance Remember that chronic acid-base disturbance(s) and/or mixed acute acid-base disturbances can be obscured by a normal pH. Consider the following “normal” values • Arterial pH: 7.40 • Arterial pCO2: 40 • Bicarb (HCO3): 24 • Anion gap: 12 Acidemia • pH 42 • Metabolic acidosis = HCO3 7.42 • Primary disturbance • Respiratory alkalosis = pCO2 26 Step 2a: Calculate and Interpret the Anion Gap • Anion gap (AG) = [Na] – [Cl] – [HCO3]. • Normal AG = 8-12 mEq/L with a serum albumin of 4g/dl. • The normal AG depends on serum albumin. The expected "normal" range for AG can be calculated by 2.5 x albumin (g/dl) +/- 2. • For severe hypoalbuminemia (2.0 g/dl), the expected gap would be 5 +/- 2, and an AG of 8-12 would be abnormally elevated. • Paraproteinemia (especially polyclonal or monoclonal IgG) can lower anion gap due to the abundance of cations added to the system; this should be accounted for when evaluating anion gap since it could obscure a truly elevated AG. • For calculation, >12 is generally used as the cutoff for a hig...