Acid Base

Question 1

4 causes respiratory alkalosis (CO2 <40)

Answer 1

Anxiety, toxic salicylates, sympathomimetics, chf, elevated ICP, hypoxia

Question 2

Causes respiratory alkalosis (co2 elevated)

Answer 2

Sedation, obtundation, coma
opioids
common and chronic in copd
respiratory failure
Neuromuscular disorders 
Obesity hypoventilation syndrome

Question 3

Causes metabolic alkalosis

Answer 3

Diuretic use 
Gastric acid losses
Hypovolemia
hyperaldosteronism
bartter syndrome

Question 4

10 causes anion gap metabolic acidosis

Answer 4

Methanol, metformin
Uremia 
Diabetic, starvation or alcoholic ketoacidosis 
Paraldehyde, propylene glycol
Iron, isoniazide, inhalant poisoning
Lactic acidosis (cyanide, sepsis, shock, hypoxia, seizures)
Ethylene glycol 
Salicylates, solvents

Question 5

Formula for anion gap

Answer 5

Sodium - (chloride + co2)

Question 6

What are the only three endogenous causes of anion gap metabolic acidosis

Answer 6

Ketones, uremia and lactate

Question 7

Causes of non anion gap metabolic acidosis

Answer 7

Hypokalemic: renal losses eg renal tubular acidosis, carbonic anhydrase inhibiotors eg acetazolamide
GI losses
Hyperkalemic: adrenal insuffiency, renal insufficiency

Question 8

Examples of causes of both anion gap metabolic acidosis and osmolar gap

Answer 8

Toxic alcohols (methanol, ethylene glycol)
Ketoacids
Paraldehyde
?sepsis

Question 9

What are the risks of sodium bicarb administration and when should it be considered in metabolic acidosis

Answer 9

Risk is electrolyte disturbances, cerebral acidosis because can’t cross the BBB
Reserve for severe acidosis (ph<7) and very ill
Salicylate toxicity is indicated

Question 10

Three settings of increased bicarbonate resulting in metabolic alkalosis

Answer 10

Gastric acid loss from vomiting or GN suctioning
Diuretic use
Mineralcorticoid excess

Question 11

Why is oxygen administration potentially dangerous in respiratory alkalosis

Answer 11

Can worsen hypercapnea in heavily sedated or obtunded patients as takes away respiratory trigger

Question 12

Presentation of alcoholic ketoacidosis

Answer 12

Chronic alcohol patient presents not intoxicated with tachycardia, tachypnea, dehydration
Fruity breath

Question 13

Lab findings alcoholic ketoacidosis

Answer 13

Anion gap metabolic acidosis
Positive b hydroxybutyrate
Ketones often negative initially
Low or negative etoh
Concomitant hypokalemia, hyponatremia, hypomagnesemia, hyperphosphatemia
Can see low, normal or high blood glucose
Normal osmolar gap
Often elevated lactate due to conversion from Pyruvate

Question 14

Management alcoholic ketoacidosis

Answer 14

Thiamine 100 mg iv before dextrose
Hydration with D5NS
Correct lytes
Insulin not required 
Bicarb only is severely acidotic

Question 15

Why should thiamine be given before D5NS in alcoholic ketoacidosis

Answer 15

Can precipitate wernicke encephalopathy

Question 16

Differential diagnosis for lactic acidosis

Answer 16

Inadequate tissue perfusion (hypotension, hypoxia)
Disorders eg diabetes, renal or hepatic failure, seizures, leukaemia, cancer
Toxins (metormin, ethanol, methanol, epinephrine, fructose)
Inborn errors of metabolism

Question 17

Three ways glucose is derived

Answer 17

Diet
Hepatic gluconeogenesis
Liver glycogen store breakdown

Question 18

Three types of ketones produced by lipolysis

Answer 18

Betahydroxybutyrate
Acetoacetate
Acetone

Question 19

10 causes of hypoglycaemia

Answer 19

Insulin
Oral hypoglycaemics eg sulfonylurea (antidote for overdose is ocreotide which inhibits insulin release)
Sepsis
Liver failure
Alcohol (inhibition gluconeogensis and depletion glycogen stores)
Malnourishment
Drugs: haldol, cimetidine, MAOi, phenothiazide
Cortisol deficiency
Endogenous hyperinsulinism eg islet cell tumor
Hypoglycaemia of infancy

Question 20

What blood tests should be ordered in non diabetic hypoglycaemic patients if cause is not obvious

Answer 20

Insulin and c peptide levels for insulinoma vs factitious hypoglycaemia

Question 21

What can be used if no iv access and patient can’t eat or drink in hypoglycaemia

Answer 21

IM glucagon (may not be effective in elderly or alcoholic)

Question 22

6 precipitants DKA

Answer 22

Lack of insulin or non compliance 
Infection
MI
Surgery
Pregnancy
Hyperthyroid
Pancreatitis
Alcohol or illicit drugs et cocaine
Steroids

Question 23

Diagnosis DKA

Answer 23

Hyperglycaemia
Ketosis
Anion gap metabolic acidosis (gap over 15,bicarb less than 18 although can be normal if concomitant vomiting, ph <7.3)
Need to ask for b hydroxybuterate assay

Question 24

Work up DKA

Answer 24

CBC lytes extended lytes bun cr lft, troponin
Vbg serum osmolality b hydroxybutyrate
Urinalysis, cxr, ecg,

Question 25

When do you start replacing potassium in DKA

Answer 25

Potassium 3.5-5 add 20-30 meq in infusion fluid

Question 26

When do you switch to half normal saline in DKA

Answer 26

When sodium has normalized

Question 27

When should bicarb be considered in DKA

Answer 27

Life threatening hyperkalemia
Ph <6.9
Shock with impending cardiovascular collapse

Question 28

Risk factors for cerebral edema with DKA management

Answer 28

Children under 5
New diagnosis
Severe acidosis 
Bicarb use
Insulin bolus

Question 29

Management cerebral edema in pediatric DKA

Answer 29

Ct head
Manage elevated ICP
Mannitol
Reduce ivf

Question 30

Differences between DKA and HHS

Answer 30

Very elevated glucose
Negative ketones
No acidosis

Can present with focal neuro deficits, altered MS, severe dehydration

Management is similar to DKA except larger water deficits
Half fluid deficit over 12 hours then switch to half normal saline
Add thiamine, correct hypo mag and hypophos