Acid Base Balance and Disorders 1

Question 1

Definition?

Answer 1

Acid-basedisorders are a group of conditions characterized by changes in the concentration of hydrogen ions (H+)orbicarbonate(HCO3-), which lead to changes in the arterialblood pH. These conditions can be categorized asacidosesoralkalosesand have a respiratory or metabolic origin, depending on the cause of the imbalance.

Question 2

Explain the findings in resp acidosis

Answer 2

low pH
high Co2
high HCo3-comp

Question 3

Mech of resp acidosis?

Answer 3

alveolar hypoventilation causes CO2 retention

Question 4

Common causes of resp acidosis?

Answer 4

Airway obstruction
acute lung diseases
resp muscle weakness
CNS depression

Question 5

Compensation?

Answer 5

buffers

increased HCO3-increased reabsorption in PCT and increased H excretion in DCT/CD

Question 6

Findings of resp alkalosis?

Answer 6

high pH
low PCO2
Low HCO3

Question 7

Mech of resp alkalosis?

Answer 7

increased resp rate and alveolar hyperventilation-CO2 washout

Question 8

Common causes of resp alkalosis?

Answer 8

pain and anxiety
preg
hypoxaemia
drugs
hyperventilation
pulomnary diseases
brainstem tumour

Question 9

Compensation for resp alkalosis?

Answer 9

buffers

low HCO3 vis less PCT reabsorption and less excretion of H

Question 10

Findings metabolic acidosis?

Answer 10

low pH
low CO2
low HCO3

Question 11

mech?

Answer 11

high production of H or loss of HCO3

Question 12

Common causes?

Answer 12

high anion gap 
M = Methanol
U = Uremia
D = Diabetic Ketoacidosis (DKA)/Alcohol Ketoacidosis 
P = Paraldehyde 
I = Isoniazid 
L = Lactic Acidosis 
E = Ethanol/Ethylene Glycol 
S = Salicylates 

normal anion gap
H=hyperalimentation
A=Addison disease
R=Renal tubular acidosis
D=diarrhoea
A=acetazolamide
S=spironolactone
S=saline infusion

Question 13

Compensation metabolic acidosis?

Answer 13

low CSF pH stimulates meduallry chemoreceptors-increased resp rate and tidal volume-increased CO2 washout and low PCO2

Question 14

Findings of metabolic alkalosis?

Answer 14

high pH
high PCO2
high HCO3

Question 15

Mech of metabolic alkalosis?

Answer 15

loss of H or increased production on HCO3

Question 16

Common causes of metabolic alkalosis

Answer 16

vomiting
hypovolaemia
loop/thiazide diuretics
hyperaldosteronsim
Cushings
Bartter
Gitelman
Liddle
high alkali load

Question 17

Compensation metabolic alkalosis

Answer 17

high CSF ph-less stimulation of medullary chemoreceptors-low resp rate and tidal vol-high CO2 retention-high PCO2

Question 18

CP acidosis?

Answer 18

headache
confusion
coma
SOB
arrhythmia
Seizures
N and V
diarrhoea

Question 19

CP alkalosis?

Answer 19

confusion
faint
tremor
numbness
twitching
N and V

Question 20

What is the anion gap?

Answer 20

Anion gap=[Unmeasured anions]- [Unmeasured cations]
anion gap=([Na+]+ [K+])- ([Cl-]+ [HCO3-])(Reference range:10–16 mmol/L)
shows difference between the concentration ofunmeasured anionsand the concentration ofunmeasured cations

Question 21

Investigations?

Answer 21

ABG
ECG
FBC
LFT's
U and E's
Serum/urine osmolaity

Question 22

Treatment?

Answer 22

• Respiratory acidosis:treat underlying cause(see “Treatment” ofCOPD,opioid intoxication,benzodiazepine overdose)
• Respiratory alkalosis:treat underlying cause; in the event ofhyperventilationsyndrome, patients benefit from reassurance andrebreathing into a paper bag.
• Metabolic acidosis
  
  • Acute severemetabolic acidosis(pH< 7.1):intravenoussodium bicarbonate
  • Chronicmetabolic acidosis: oralsodium bicarbonatealong with treatment of the underlying cause (e.g.,diarrhea,renal tubular acidosis)
  • Electrolyte disturbances: correct (e.g., see “Treatment” inhyperkalemia).
  • See individual articles for the management ofdiabetic ketoacidosis,salicylate toxicity.
• Metabolic alkalosis
  
  • Volume depletion:isotonic salineto increase urinarybicarbonateexcretion and correct extracellular volume loss
  • Bicarbonateexcess:acetazolamide
  • Electrolyte disturbances: correct (e.g., see “Treatment” ofpotassium disorders)

Question 23

P?

Answer 23

• Life-threatening if left untreated

Can be reversible

Question 24

Complications?

Answer 24

See table-4 systems