Acid Base disturbances Flashcards
what is the absolute base line for pH levels, especially when considering mixed disorders?
7.40
Respiratory Acidosis Labs
pH-decreased
CO2-increased
bicarb- increased
what is the compensatory mechanism from the kidneys?
slow increase in plasma bicarb
what can cause RAci?
failure of lung to excrete CO2 from either alveolar hypoventilation leading to pulmonary CO2 retention or overproduction of CO2
what are the primary causes of RAc
any disorder that reduces pulmonary function and CO2 clearance- primary pulmonary dz, neuromuscular dz (myasthenia gravis) , primary CNS, parental nutrition
Clinical features of respiratory acidosis
metabolic encephalopathy- headaches and drowsiness
hypoxemia
lab findings for R ACid
ph decreased, PCO2 increased
2-5 days later plasma bicarb increased
tx for RAC
underlying disorder corrected
when to intubate pt in RAc?
when the PCO2 greater than 60 mmHg
Ralk?
decreased blood PCO2 and increased blood pH
PP of RAl?
excessive elimination of CO2 from increased ventalory drive
response- kidneys will gradually eliminate plasma bicarb
what is the most common cause of respiratory alk?
anxiety! (hysterical hyperventilation)
other causes of R Alk?
salicylate intoxication, hypoxia, intrathoracic disorders, primary CNS dysfxn , gram neg sepicemia, liver insuffic, PREGO? bad ventilator settings
CF of RAlk?
hyperventilation
breathing patter- frequent, deep, sighing respirations, to rapid deep breathing
acroparesthesias- burning of hands and feet
what is acute alkalemia similar too?
hypocalemia- may produced a tetany-like syndrome
paresthesia of the extremities, chest discomfort, light-headedness, and confusion
Lab findings of R. ALk?
PH increased, PCO2 decreased,
decreased in Plasma bicarb, serum chloride levels elevated- maintain electroneutrality
Treatment of RAL
light sedation- rebreathing techniques have fallen out of favor bc additional anxiety
when is CO2 breathing mixtures of controlled ventilation requried?
when pH > 7.6
Metabolic Acidosis?
elevation in H ion due to loss of bicarb or addition of H ions to serum
what is the immediate response of metabolic acidosis?
increase in respiration
what can cause an increase in Blood pH? and an increased anion gap?
lactic acidosis, DKA, starvation ketosis, ethylene glycol, methanol or salicylate intoxication
H ions may also be retained in renal tubular acidosis, renal insufficiency and adrenal insuficiency
what are conditions that cause M Ac but with normal AG?
Diarrhea, pancreatic or biliary drainage, and uretral diversion
CF of Met AC
hyperventilation- stimulation of respiratory drive to blow off CO2
- ventricular arrhythmias
- lethargy to frank coma
what is winter’s formula?
PCO2= {1.5 X HCO3-] + 8 +/- 2
calculation of the expected PCO2 compensation
Lab Studies for MAc
** bicarb follows the pH in metabolic disorders
make sure to calculate the AG
What is hyperchloremic Metabolic acidosis?
Cl ion increased as bicarb decreased to maintain electroneutrality
(normal AG acidosis)
common cuases of Normal AG renal tubular acidosis?
-either kidney failing to reabsorb bicarb or secrete acid
USED CARP
what does USED CARP stand for?
Ureteroenterostomy
Small bowel fistual
Endocrinopathies/extra Cl
Diarrhea
Carbonic anhydrase inhibitors
Ammonium chloride
Renal tubular acidosis
Pancreatic Fistula
What must be taken into considerations when calculating AG?
negative charge of albumin can impact overall AG
-hypoalbumiemia present: for each 1.0 g/dL decrease in serum albumin, the AD should be increasd by 2.5
how is AG calculated?
Na - [HCO3- + Cl-]; normal is 8+/- 4
what may cause elevated AG Acidosis?
- lactic acidosis
- ketoacidosis
- toxins/drugs
- kidney failure
what does CAT MUD PILES stand for?
Carbon Monoxide/Cyanide Alcoholic ketoacidosis Toluene methanol Uremia DKA Paraldehyde Infection/Iron/Isoniazide Lactic Acidosis Ethylene glycol (antifreeze) Salicylates (ASA)
tx of MAc
remove primary cuase
Insulin therapy and volume repletion for DKA
when do you use Bicarb tx for MAc?
when pH less than 7.20
Metabolic Alkalosis?
increase in surm bicarb w/ no change in PCO2
pH > 7.42
PP of m.alk?
kidney fails to excrete the excess bicarb
CO2 compensation= (0.7 X HCO3-) + 20 +/- 2
what can cause M. Alk?
Vomiting, addition of bicarb (hyperalimentation therapy PPN) or Diarrhea (caused by loss of Cl)
-V
-NG tube suctioning
Villious adenoma
Chloride D
diuretics
hypercalcemia
milk-alki syndrome
mineralocorticoid excess
Bartter and Gitelman syndromes
Cl/K depletions of excessive steroids
CF of Met Alk?
neuroligic abnormlaties
-low ionized Calcium: paresthesias, carpopedal spasm, light headedness
- stupor, coma
- sx from volume depletion: wksn, muscle cramps, postural dizzy
- sx from K depletion: polyuria, polydipsia, weakness
what does urine Chloride concentrations tell you in a met. alk pt?
hypovolemic hypochloremic patients w/ decreased urine Cl (< 20)
volume expanded pts- mineralocorticoid excess who have urine chloride concentrations > 30
what are some interventions to help met. alk pts?
increase renal excretion of bicarb
depends on whether or not pt is chloride responsive
what are some Chloride responsive condtions of Met. Alk? what is the tx?
gastric fluid loss, diuretic therapy
tx- NaCl
Chloride resistant conditions and tx?
mineralcorticoid excess: removal of adrenal ademona
spironolactone- aldosterone antagonist
