Acid Base Balance and Disorders 1 Flashcards
Definition?
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.
Explain the findings in resp acidosis
low pH
high Co2
high HCo3-comp
Mech of resp acidosis?
alveolar hypoventilation causes CO2 retention
Common causes of resp acidosis?
Airway obstruction
acute lung diseases
resp muscle weakness
CNS depression
Compensation?
buffers
increased HCO3-increased reabsorption in PCT and increased H excretion in DCT/CD
Findings of resp alkalosis?
high pH
low PCO2
Low HCO3
Mech of resp alkalosis?
increased resp rate and alveolar hyperventilation-CO2 washout
Common causes of resp alkalosis?
pain and anxiety preg hypoxaemia drugs hyperventilation pulomnary diseases brainstem tumour
Compensation for resp alkalosis?
buffers
low HCO3 vis less PCT reabsorption and less excretion of H
Findings metabolic acidosis?
low pH
low CO2
low HCO3
mech?
high production of H or loss of HCO3
Common causes?
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
Compensation metabolic acidosis?
low CSF pH stimulates meduallry chemoreceptors-increased resp rate and tidal volume-increased CO2 washout and low PCO2
Findings of metabolic alkalosis?
high pH
high PCO2
high HCO3
Mech of metabolic alkalosis?
loss of H or increased production on HCO3
Common causes of metabolic alkalosis
vomiting hypovolaemia loop/thiazide diuretics hyperaldosteronsim Cushings Bartter Gitelman Liddle high alkali load
Compensation metabolic alkalosis
high CSF ph-less stimulation of medullary chemoreceptors-low resp rate and tidal vol-high CO2 retention-high PCO2
CP acidosis?
headache confusion coma SOB arrhythmia Seizures N and V diarrhoea
CP alkalosis?
confusion faint tremor numbness twitching N and V
What is the anion gap?
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
Investigations?
ABG ECG FBC LFT's U and E's Serum/urine osmolaity
Treatment?
- 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)
P?
• Life-threatening if left untreated
Can be reversible
Complications?
See table-4 systems
