Nephro-Acid Base Flashcards
Steps to analyze Acid-Base
- Look at serum bicarb–is it a primary acidosis or alkalosis?
- Look at the CO2-is it respiratory or metabolic?
In a metabolic acidosis, what do you look at first?
You look for an anion gap
AG=Sodium-(Cl+Bicarb)
What is the pathology behind AG metabolic acidosis?
Unmeasured organic anion, such as lactate
What is the pathology behind non-AG metabolic acidosis?
Bicarb loss
What is a normal AG?
8-10
How does serum albumin impact anion gap?
Decreased albumin, decreases the anion gap, whereas ppl with high albumin have a higher anion gap
Corrected AG= AG+(2.5 x (normal albumin-measured albumin))
When there is a change in anion gap from albumin, how do you correct the bicarb?
What happens if the measured bicarb is less than the normal bicarb?
You correct the bicarb by…
Corrected bicarb=24 mEq - (change anion gap from albumin)
You get a concomitant metabolic alkalosis if the measured bicarb is greater than the corrected one
You have a concurrent non-anion gap metabolic acidosis if the measured bicarb is less than the corrected one
What are the two methods to see if there is a concurrent mixed AB disorder?
- corrected bicarb, if albumin high or low
2. delta delta
How is the delta delta calculated?
It is the the change in anion gap divided by the change in the bicarb.
Ratio <1: reflects the presence of concurrent normal AG metabolic acidosis
Ratio >2: indicates the presence of a metabolic alkalosis
Causes of an increased anion gap metabolic acidosis
MUDPILES methanol uremia diabetic keotacidosis polyethylene glycol ingestions: Tylenol, salicylates, Lactic acidosis Ethylene glycol Salicylate toxicity
What are the causes of type A, B, and D lactic acidosis?
TYPE A: Tissue hypoperfusion
TYPE B: propofol, metformin, hematological malignancy (seen in high grade b-cell lymphomes from anaerobic metabolism of cancer cells)
TYPE D: short bowel syndrome, undigested carbohydrates in the colon are metabolized to D-lacatate
What are the clinical manifestations of Type D Lactic Acidosis? What is the treatment? How is it diagnosed?
Intermittent confusion, slurred speech, ataxia, increased AG metabolic acidosis with NORMAL serum lactate level
TREATMENT: Antibiotics directed toward bowel flora; restriction of dietary carbs
DIAGNOSIS: Measurement of D-lactate
What is the pathology of ethylene glycol ingestion? Clinical symptoms? Treatment?
glycolic acid accumulation; calcium oxalate precipitation in renal tubules and crystals in the urine
flank pain; nephrocalcinosis; CV collapse; pulmonary edema
Treatment: HD, FOmepizole, sodium bicarbonate and pyridoxine/thiamine in suspected ethylene glycol toxicity
What is the pathology of methanol ingestion? Clinical symptoms? Treatment?
Formic acid ingestion
Impaired vision/ blindness mediated by formic acid’ papullemeda; mydriasis; afferent pupillary defect; abdominal pain; pancreatitis
Treatment: HD, fomepizole, sodium bicarbonate
What is the pathology of propylene glycol toxicity? Clinical symptoms? Treatment?
It is used a lot to dilute medications and so large doses accidentally given (such as with lorazepam) can cause it
You get an AKI, AG metabolic acidosis with increased plasma osmolal gap
Treatment: d/c the IV infusion
What is the pathology of salicylate toxicity?
Clinical symptoms? Treatment?
Salicylate anion accumulation
Clinical: Tinnitus, tachypnea, impaired mental status, cerebral edema, fatal brainstem herniation… lactic acidosis.. lots of things…
Treatment: IV glucose (100mL of 50% dextrose) in adults when MENTAL STATUS CHANGES ARE PRESENT irrespective of plasma glucose level
HD for AKI, imparted mental stately, cerebral edea, severe AG MA, pulmonary edema, salicylate >80
Vitamin K for increased INR
Acetaminophen toxicity: what is the pathology? clinical symptoms? treatment?
common in those who are critically ill, poor nutrition, liver disease, CKD, and in vegetarians;
clinical: impaired mental status, high concentrations in the urine of pyroglutamate
treatment: discontinue acetaminophen, sodium bicarb
What next step do you take if you have a NAGMA?
Check urine anion gap!
Uag=(Una+Uk)-Ucl
Causes of negative urine AG: ammonium chloride ingestion, diarrhea/acidosis, Type 2 proximal RTA
Causes of positive urine AG: Type I RTA, Type 4 RTA
What is a type 2 RTA? Why does it occur?
Defect in the proximal tubule results in a diminished ability to reabsorb filtered bicarb.
Causes: hereditary, sporadic/transient, Fanconi syndrome
Usually part of Fanconi syndrome
Treat with a thiazide diuretic
What is a type 1 RTA? Why does it occur? How is it treated?
Hypokalemic, distal RTA
people with a type I RTA are unable to acidify the pH of their urine
Treat with potassium citrate
Type 4 RTA? What is it? Why does it occur? How is it treated?
Hyperkalemic, Distal RTA
Drug induced very common: seizure meds, ACE-Inhibotrs, TMP, heparin,
Aldosterone deficiency or resistance
Treatment: treat hyperkalemia, stop meds causing it, restrict potassium
What is the first thing you do if someone has a metabolic alkalosis?
You assess blood pressure and volume status to create differential
Metabolic alkalosis, increased extracellular fluid, low blood pressure?
CHF, cirrhosis, nephrotic syndrome
Metabolic alkalosis, normal/low blood pressure, urine chloride is low <15?
vomiting
Metabolic alkalosis, normal/low blood pressure, urine chloride is low >15?
active diuretic use hypokalemia hypomagnesemia Aminoglycoside toxicity Bartter/Gitelman syndrome
Metabolic alkalosis, blood pressure increased, urine sodium and urine chloride high >15?
Renin secreting tumor Malignant hypertension Renovascular hypertension Primary hyperaldosteronism Mineralcorticoid excess (Ectopic ACTH syndrome)
Causes of Respiratory alkalosis
ENHANCED RESPIRATORY DRIVE
sepsis, hepatic failure, anxiety, psychosis, pregnancy, nicotine, salicylates
HYPOXEMIA
high altitude, severe anemia, hypotension, chronic heart failure, pulmonary parenchymal disease
PULMONARY DISEASE WITH THORACIC STRETCH RECEPTOR STIMULATION
pneumonia, ARDS, PE, hemothorax, pneumothorax, pulmonary edema
