Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
21 Cards in this Set
- Front
- Back
What is an anion gap?
|
Anion gap= (Na+) – (Cl- + HCO3-)
Normal anion gap: 12 +/- 2 Albumin x 3 = expected anion gap In metabolic acidosis, bicarbonate is diminished while other anions are increased |
|
What are the common causes of anion gap?
|
MUDPILES
Methanol (formic acid) Uremia Diabetic ketoacidosis Paraldehyde/phenformin Iron tablets/INH Lactic acidosis Ethylene glycol (oxalic acid) Salicylates |
|
What's the delta gap?
|
Delta Gap=Measured AG – Expected AG; then add to measured HCO3-
If answer <24 con-commitant NAGMA If answer >24 con-commitant Metabolic Alkalosis (Another way to say this: What was the Bicarb before the Anion was introduced?) |
|
What's compensation?
|
respiratory system compensates for acidemia or alkalemia by either hyperventilation (acidemia response) or hypventilation (alkalemia response)
Winters Formula used for Acidosis: 1.5 * HCO3 + 8 = PCO2 +/- 2 Formula for Alkalosis (Summer’s Formula): 0.7 * HCO3 + 20= PCO2 +/- 5 |
|
Case 1
Sodium 132 mEq/L Urea Nitrogen 38 mg/dL Potassium 6.0 mEq/L creatinine 2.6 mg/dL Chloride 93 mEq/L Bicarbonate 11 mEq/L Glucose 720 mg/dL Arterial blood gas analysis reveals: pH 7.26 and PCO2 25 mmHg |
Step 1: pH 7.26-Acidemia
Step 2: pH down; PCO2 down (compensation) = metabolic acidosis Step 3: AG=(Na+) – (Cl- + HCO3-); (132) - (93 + 11) = 28 Step 4a: Winter's formula-ePCO2= 1.5 * 11 + 8= 24.5 +/- 2 Step 4b: Delta Gap= (28-12) +11=27 (con-commitant metabolic alkalosis) Step 5-Differential Diagnosis Step 6-Treatment |
|
Case 2 labs
Sodium 145 mEq/L Urea Nitrogen 70 mg/dL Potassium 1.9 mEq/L creatinine 1.5 mg/dL baseline creatinine 0.8 mg/dL)Chloride 86 mEq/L Bicarbonate 45 mEq/L pH 7.59 and PCO2 49 mmHg Spot Urine Chloride is 74 mEq/L |
Step 1-Alkalemia
Step 2-pH up; PCO2 up = metabolic alkalosis Step 3: AG-145 - (86 + 45)= 14 Step 4: Summer formula-ePCO2= 0.7 * 45 + 20= 51.5 +/- 5 Step 5-Differential Diagnosis Step 6-Treatment |
|
What's metabolic alkalosis?
|
Net loss of H+
Net addition of HCO3 (alkalai ingestion) External loss of fluid containing Cl- (contraction alkalosis) |
|
Describe chloride responsive vs chloride non-responsive metabolic alkalosis
|
Chloride-responsive-Urine Chloride <15-20 mEq/L
Chloride Non-responsive-Urine Chloride >20 |
|
What are chloride responsive causes of metabolic alkalosis?
|
Vomiting and NG suction
Diarrhea Diuretics Post-hypercapneic state |
|
What are chloride non-responsive causes of metabolic alkalosis?
|
A. Mineralocorticoid excess (primary hyperaldosteronism, Adenoma, Cushing’s syndrome)
B. Apparent excess of mineralocorticoid (Licorice or Altoids, Liddle’s syndrome) C. High dose Glucocorticoids D. Normotensive-Severe K+ deficiency |
|
Case 3 Labs:
Serum lab values are: Sodium 138 mEq/L Urea Nitrogen 28 mg/dL Potassium 4.2 mEq/L creatinine 1.1 mg/dL Chloride 112 mEq/L Bicarbonate 14 mEq/L Spot Urine Electrolytes: Sodium 100 mEq/L, Potassium 31 mEq/L, Chloride 105 mEq/L Arterial blood gas analysis reveals: pH 7.32 and PCO2 28 mmHg |
Step 1-Acidemia
Step 2-pH down; PCO2 down = metabolic acidosis Step 3: AG-138 - (112 + 14) = 12 Step 4: winter's formula-ePCO2= 1.5 * 14 + 8=29 +/- 2 Step 5-Differential Diagnosis Step 6-Treatment |
|
What's happened in a non-anion gap metabolic acidosis (NAGMA)?
|
bicarbonate is diminshed
chloride is increased |
|
What's a urinary anion gap?
|
Urinary Anion Gap:
UAG= (Na + K+) – Cl-; In a normal acid-base state, the UAG is (+) 30-50 mEq/l Normal kidney function in metabolic acidosis, the UAG should be (-) 30-50 mEq/l, indicating a large amount of unmeasured ammonium cation (increased as extra H+ is secreted and paired w/ NH3 to be excreted as NH4). Negative value suggests extra-renal origin (NH4+ in urine is the normal kidney response in the face of an acidosis) Positive value suggests a renal origin in the presence of an acidosis |
|
What are the types of renal tubular acidosis?
|
Type I (distal)
Type II (proximal) Type IV RTA of renal failure |
|
decreased H+ secretion
Normo-hypokalemia Urine pH >5.3 HCO3<10 meq/L Nephrocalcinosis Urine pH constant |
Type I (distal) RTA
|
|
decreased HCO3 reclamation
Normo-hypokalemia Urine pH <5.3 HCO3 14-20 Urine pH variable |
Type II (proximal) RTA
|
|
Aldosterone deficiency
Hyperkalemia Urine pH < 5.3 HCO3 > 15 Associated with Diabetes Measure Aldosterone |
Type IV RTA
|
|
Decreased renal mass
Hyperkalemia Urine pH < 5.5 Abnormal renal function |
RTA of renal failure
|
|
A 68-year-old-woman is admitted with a one-week history of severe diarrhea. She is weak and appears lethargic. Blood pressure is 100/60 mmHg ( supine) and 70/40 mmHg (sitting). Mucous membranes are dry and there is poor skin turgor. There is no JVD or S3. Lungs are clear to auscultation. There is no peripheral edema. A Foley catheter is placed and a trace amount of dark urine is drained and is sent for analysis. She is begun on intravenous fluids. Urine output improves with fluid repletion.
Admission serum lab values are: Sodium 137 mEq/L Urea Nitrogen 77 mg/dL Potassium 2.5 mEq/L creatinine 3.0 mg/dL Chloride 118 mEq/L Bicarbonate 4.2 mEq/L Spot urine electrolytes are: Sodium 25 mEq/L Chloride 108 mEq/L Potassium 40 mEq/L Arterial blood gas analysis reveals: pH 7.04 and PCO2 16 mmHg |
Step 1-Acidemia
Step 2-pH down; PCO2 down = metabolic acidosis Step 3-AG= 15 Step 4: winter's formula-ePCO2= 1.5 * 5 + 8= 15.5 +/- 2 Step 5 -Differential Diagnosis Step 6-Treatment |
|
What are the causes of NAGMA (non anion gap metabolic acidosis)?
|
diarrhea
glue sniffing RTA hyperchloremia |
|
What are Barnes' steps to acid-base disorders?
|
1. Determine if the blood is Acidemic or Alkalemic
2. Determine the direction in change of PCO2 and pH (up or down from normal values) 3. Calculate the Anion Gap 4. PCO2 and HCO3 compensation; is there a mixed disorder a. Winters formula: Expected pCO2 = 1.5 * HCO3- + 8 +/- 2 b. Delta Gap; Measured AG – Normal AG; then add to measured HCO3- c. Metabolic Alkalosis: Expected pCO2 = 0.7 [HCO3] + 20 mmHg (range: +/- 5) 5. Map out your Differential Diagnosis 6. Treat underlying conditions unless pH in dangerous range, then treat with acute management. |