INTERACTIVE CASE DISCUSSION Acid-Base Disorders (Part I)

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


CASE #1:• Serum Na = 138meq/l• Serum K= 4.2meq/l• Serum Cl= 108meq/l

• Serum HCO3 = 10meq/l

• Glucose = 350 mg/dl

• ABGs: pH = 7.30, pCO2 = 23 mmHg, pO2 = 92 mmHg (room air)


QUESTION #1: What is the acid-base disorder present?

A. Metabolic acidosis

B. Metabolic alkalosis

C. Respiratory acidosis

D. Respiratory alkalosis


ANSWER #1: Metabolic acidosis

ABGs: pH = 7.30 ()pCO2 = 23 ()

HCO3 = 10 ()

pCO2 = ( 1.5 X HCO3) + 8

= ( 1.5 X 10 ) + 8

= 23 mmHg


QUESTION #2: How will you systematically approach the present acid-base problem?


W ide Anion Gap(>12)

Norm al Anion Gap(5-11)

Serum Anion G ap(5-11)

M etabolic acidosis

ANSWER #2:


QUESTION #3: What is the calculated serum anion gap in this case ?


ANSWER #3:

Anion gap = Na – (Cl + HCO3)

= 138 – (108 + 10)

= 138 – 118

= 20

( Wide gap metabolic acidosis)


QUESTION #4: In general, what are the causes of a wide anion gap metabolic acidosis?


ANSWER #4:Causes of a Wide Gap Metabolic Acidosis• Lactic acidosis• Ketoacidosis: diabetes, alcoholism,

starvation• Toxins: salicylates, methanol, ethylene

glycol• Renal failure


CASE #1: Other Laboratory Results

Serum creatinine = 1 mg/dl

Serum ketones = negative

Serum lactate = 3 meq/l


QUESTION #5: In this particular patient, what is the cause of the acid-base disorder?


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)

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


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



A. Metabolic acidosis

B. Metabolic alkalosis

C. Respiratory acidosis

D. Respiratory alkalosis


ANSWER #1: Metabolic acidosis

ABGs: pH = 7.30 ()pCO2 = 20 ()HCO3 = 8 ()pCO2 = (1.5 X HCO3) + 8

= (1.5 X 8) + 8

= 20



A c i d - B a s e D i s o r d e r s ( P a r t I I )

W ide Anion Gap(>12)

Norm al Anion Gap(5-11)

Serum Anion Gap(5-11)

M etabolic acidosis

A N S W E R # 2 :


QUESTION #3: What is the calculated serum anion gap in this case?


ANSWER #3:

Anion gap = Na – (Cl + HCO3)

= 140 – (124 + 8)

= 8

( Normal anion gap metabolic acidosis)


QUESTION #4: In general, what are the causes of a normal anion gap metabolic acidosis?


Causes of Normal Gap Metabolic AcidosisI. 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


• QUESTION #5: In this particular case, what is the cause of the normal anion gap metabolic acidosis?


ANSWER #5 :

• Diarrhea –due to Na and HCO3 losses


Acid-Base Disorders

(Part III)

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


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




ANSWER #1: Metabolic alkalosisABGs: pH = 7.5 ()

pCO2 = 56 ()HCO3 = 42 ()pCO2 = 0.75 (HCO3)

= 0.75 (14) = 10.5

pCO2 = 45 + 10.5 = 56




Cl Responsive(Urine Cl < 25)

Cl Resistant(Urine Cl> 40)

M etabolic alkalosis


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


ANSWER #3: Causes of Metabolic Alkalosis• Chloride Responsive (Urine Cl < 25): Vomiting, NGT suction, diuretics

(late), factitious diarrhea, low Cl intake, posthypercapnia, cystic fibrosis


• Chloride Resistant (Urine Cl > 45):

Primary mineralocorticoid excess, diuretics (early), alkali load, Bartter’s or Gitelman’s syndrome, severe hypokalemia


QUESTION #4: In this particular case, what is the cause of the metabolic alkalosis?


ANSWER #4: Vomiting

• History of vomiting

• Signs of dehydration

• Urine chloride = 8 meq/L (< 25), Cl responsive type of metabolic alkalosis

INTERACTIVE CASE DISCUSSION Acid-Base Disorders (Part I)

Documents

acid base disorder

meql slide

acidbase disorder present

present acidbase problem

acid loads

mmhg slide

hippurate slide

respiratory alkalosis