INTERACTIVE CASE DISCUSSION Acid-Base Disorders (Part I)

Acid-Base Disorders (Part I) CASE #1: 24 y/o male with insulin-dependent diabetes mellitus 2 day history of fever and diarrhea BP=80/60, PR = 120/min, RR= 35/min,T = 39 C Dry mucous membranes, poor skin turgor, flat neck veins Clear breath sounds Abdomen soft, hyperactive bowel sounds

Acid-Base Disorders (Part I) CASE #1: Serum Na = 138meq/l Serum K= 4.2meq/l Serum Cl= 108meq/l Serum HCO 3 = 10meq/l Glucose = 350 mg/dl ABGs: pH = 7.30, pCO 2 = 23 mmHg, pO 2 = 92 mmHg (room air)

Acid-Base Disorders (Part I) QUESTION #1: What is the acid-base disorder present? A.Metabolic acidosis B.Metabolic alkalosis C.Respiratory acidosis D.Respiratory alkalosis

Acid-Base Disorders (Part I) ANSWER #1: Metabolic acidosis ABGs:pH = 7.30 ( ) pCO 2 = 23 ( ) HCO 3 = 10 ( ) pCO 2 = ( 1.5 X HCO 3 ) + 8 = ( 1.5 X 10 ) + 8 = 23 mmHg

Acid-Base Disorders (Part I) QUESTION #2: How will you systematically approach the present acid-base problem?

Acid-Base Disorders (Part I) ANSWER #2:

Acid-Base Disorders (Part I) QUESTION #3: What is the calculated serum anion gap in this case ?

Acid-Base Disorders (Part I) ANSWER #3: Anion gap = Na – (Cl + HCO3) = 138 – ( ) = 138 – 118 = 20 ( Wide gap metabolic acidosis)

Acid-Base Disorders (Part I) QUESTION #4: In general, what are the causes of a wide anion gap metabolic acidosis?

Acid-Base Disorders (Part I) ANSWER #4: Causes of a Wide Gap Metabolic Acidosis Lactic acidosis Ketoacidosis: diabetes, alcoholism, starvation Toxins: salicylates, methanol, ethylene glycol Renal failure

Acid-Base Disorders (Part I) CASE #1: Other Laboratory Results Serum creatinine = 1 mg/dl Serum ketones = negative Serum lactate = 3 meq/l

Acid-Base Disorders (Part I) QUESTION #5: In this particular patient, what is the cause of the acid- base disorder?

Acid-Base Disorders (Part I) ANSWER #5: Lactic acidosis No history of toxin ingestion Normal kidney function Negative serum ketones Hypotensive with an elevated serum lactate

Acid-Base Disorders Part II Case #2: 50 year old female with fever and diarrhea of two days duration No previous illness; not on any medicines BP =104/60, HR = 96/minute, RR = 30/min Clear breath sounds Hyperactive bowel sounds

Acid-Base Disorders Part II Case #2: ABGs at RA: pH = 7.30, pCO2 = 20, pO2 = 90, HCO3 = 8 Serum Na = 140 meq/L Serum K = 3.6 meq/L Serum Cl = 124 meq/L Serum HCO3 = 8 meq/L

Acid-Base Disorders Part II QUESTION #1: What is the acid-base disorder present? A.Metabolic acidosis B.Metabolic alkalosis C.Respiratory acidosis D.Respiratory alkalosis

Acid-Base Disorders Part II ANSWER #1: Metabolic acidosis ABGs:pH = 7.30 ( ) pCO2 = 20 ( ) HCO3 = 8 ( ) pCO2 = (1.5 X HCO3) + 8 = (1.5 X 8) + 8 = 20

Acid-Base Disorders Part II QUESTION #2: How will you systematically approach the present acid-base problem?

Acid-Base Disorders Part II QUESTION #3: What is the calculated serum anion gap in this case?

Acid-Base Disorders Part II ANSWER #3: Anion gap = Na – (Cl + HCO3) = 140 – ( ) = 8 ( Normal anion gap metabolic acidosis)

Acid-Base Disorders Part II QUESTION #4: In general, what are the causes of a normal anion gap metabolic acidosis?

Acid-Base Disorders Part II Causes of Normal Gap Metabolic Acidosis I.Gastrointestinal Bicarbonate Losses : diarrhea, small bowel drainage, ureterosigmoidostomy, jejunal loop, ileal loop II.Renal Bicarbonate Losses : Renal Tubular Acidosis Types I, II and IV III.Drugs : K-sparing diuretics, trimethoprim, pentamidine, ACE-I, NSAIDs, cyclosporine IV.Others: Acid loads, ketosis with ketone excretion, expansion acidosis, hippurate

Acid-Base Disorders Part II QUESTION #5: In this particular case, what is the cause of the normal anion gap metabolic acidosis?

Acid-Base Disorders Part II ANSWER #5 : Diarrhea –due to Na and HCO3 losses

Acid-Base Disorders Part III Case # 3: 65 year old male with nausea and severe vomiting of three days duration Also with atopic dermatitis on high dose steroids BP = 90/60, HR= 120/min., RR = 20/min JVP = 4 cm,dry mucosa, clear breath sounds Abdomen distended, active bowel sounds Skin: poor skin turgor, multiple plaques with excoriations

Acid-Base Disorders Part III Case #3: ABGs at RA: pH = 7.50, pCO2 = 56, pO2 = 92, HCO3 = 42 Serum Na = 144 meq/L Serum K = 3.6 meq/L Serum Cl = 81 meq/L Serum HCO3 = 42 meq/L Urine Na = 5 meq/L, Urine Cl = 8 meq/L

Acid-Base Disorders Part III QUESTION #1: What is the acid-base disorder present?

Acid-Base Disorders Part III ANSWER #1: Metabolic alkalosis ABGs:pH = 7.5 ( ) pCO2 = 56 ( ) HCO3 = 42 ( ) pCO2 = 0.75 ( HCO3) = 0.75 (14) = 10.5 pCO2 = = 56

Acid-Base Disorders Part III QUESTION #2: How will you systematically approach the present acid-base problem?

Acid-Base Disorders Part III

Question #3: In general, what are the causes of metabolic alkalosis?

Acid-Base Disorders Part III ANSWER #3: Causes of Metabolic Alkalosis Chloride Responsive (Urine Cl < 25): Vomiting, NGT suction, diuretics (late), factitious diarrhea, low Cl intake, posthypercapnia, cystic fibrosis

Acid-Base Disorders Part III Chloride Resistant (Urine Cl > 45): Primary mineralocorticoid excess, diuretics (early), alkali load, Bartters or Gitelmans syndrome, severe hypokalemia

Acid-Base Disorders Part III QUESTION #4: In this particular case, what is the cause of the metabolic alkalosis?

Acid-Base Disorders Part III ANSWER #4: Vomiting History of vomiting Signs of dehydration Urine chloride = 8 meq/L (< 25), Cl responsive type of metabolic alkalosis