17. Intro to Acid-Base Disturbances Flashcards
what is the time course of acid-base compensatory mechanisms
cellular buffering process
resp compensation
renal base excretion
renal acid excretion
(renal takes longer to act than resp)
what is the acid-base (davenport) nomogram diagram
& what does it show
the areas of acidosis & alkalosis
2 curves for resp bc kidneys take longer to respond - so graph shows acute and chronic resp changes
if metabolic acidosis-
calculate anion gap
if metabolic alkalosis -
have to decide if compensation if appropriate or if its a mixed disorder
decide if chloride resistant (urineCl>20) or responsive (urineCl<10)
how do you calculate anion gap
Na - (Cl + HCO3)
= 11-12
high = metabolic acidosis
what does it mean if you have a high anion gap
other solutes in plasma (alcohols, lactic acidosis, ketoacidosis)
metabolic acidosis
= GOLDMARK (glycol, oxoproline, L-lactate, D-lactate, methanol, aspirin, renal failure, ketoacidosis)
how to calculate Osm gap
what does it mean if Osm gap is > 10
other solute in plasma (alcohols, lactic acidosis, ketoacidosis)
how to you calculate URINE anion gap
what is the result in metabolic acidosis
Na + K - Cl
= -20 to -50 in metabolic acidosis due to bicarb loss in diarrhea since excretion of unmeasured NH4+ increases
what does the Osmolal gap equal if pt presents chronic severe metabolic acidosis or renal tubular acidosis
chronic severe metabolic acidosis - 200-300 (> 0 bc unmeasured osm particles)
renal tubular acidosis - < 75
what are causes for acute resp acidosis
“CANS”
CNS depression (opiates)
Airway obstruction
Neuromuscular disorder (myasthenia gravis)
Severe pneumonia, embolism, edema
what are reasons for chronic resp acidosis
COPD
anything chronic that leads to imparied ventilation
what are symptoms of acute resp acidosis
headache, confusion, anxiety, drowsiness, stupor tremors, convulsions, possible coma
what are the symptoms if slow developing respiratory acidosis
memory loss, sleep disturbances, excessive daytime sleepiness, personality changes
-gait probs, tremor, blunted deep tendon reflex, myoclonic jerks, asterixis (flapping wrist) & papilledma
How much does [HCO3-] need to compensate for acute & chronic resp acidosis
for every 10 changes in PaCO2
acute - increase 1 mEq/L HCO3-
chronic- increase 3.5 mEq/L HCO3-
if compensation of resp acidosis/alkalosis
isnt whats expected –
then you get mixed acid-base disorder
what are the causes of resp alkalosis
CHAMPS
CNS disease - hyperventilation
Hypoxia
Anxiety
Mechanical ventilators
Progesterone
Salicylates (aspirin)/Sepsis
what are the symptoms of acute & chronic resp alkalosis
acute - light headedness, confusion, peripheral/cicumoral paresthesia, cramps, syncope, tachypnea/hyperpnea - severe = carpopedal spasm bc low Ca
chronic - asymptomatic
what is the expectation or HCO3- compensation for resp alkalosis
for every 10 PaCO2 decreased
acute - decrease HCO3 by 2 mEq/L
chronic - decrease HCO3 by 5 mEq/L
what are the causes of High Anion Gap Metabolic Acidosis
(HAGMA)
GOLDMARK
Glycols
Oxoproline
Lactate
D-lactate
Methanol
Aspirin
Renal failure
Ketoacidosis
what are the causes of Non-Anion Gap Metabolic Acidosis
HARDUPS {* = main causes)
Hyperalimentation
Acetazolamide
Renal tubular acidosis (1, 2, 4) *
Diarrhea *
Ureterosigmoid fistula
Posthypocapnia Pancreatic fistula
Spironolactone
what are the symptoms of metabolic acidosis
how is it compensated
mild- asymptomatic
< 7.1 –> nausea, vomitting, malaise
(resp
compensation - long deep breaths at NORMAL rate)
how do you calculate expected resp compensation for metabolic acidosis
PaCO2 = (1.5*HCO3-) + 8 plus/minus 2
or
PaCO2 =40 - (1.2 * (24-HCO3))
what if resp compensation isnt whats expected
= mixed acid-base disorder
