Resus Pearls, part 2 Flashcards
These consist primarily of the statements in bold font in Tintinalli.
Normal respiratory compensation in metabolic acidosis
PCO2 decreases by 1 mm Hg for every 1 mEq/L net decrease in HCO3
Remarks on lactic acidosis
Lactic acidosis is not a diagnosis, but a syndrome with its own differential diagnosis
Remarks on ethanol and metabolic acidosis
Ethanol should never be considered the cause of any significant metabolic acidosis
The most important step in treatment of metabolic acidosis
To determine whether there is a respiratory component to the acidosis (i.e., a primary respiratory acidosis)
If tehre is inadequate respiratory compensation, the most appropriate treatment will be to first correct the respiratory problem.
Compensation in metabolic alkalosis
As a guidline, PCO2 in patients with significant metabolic alkalosis should rise by 0.7 mm Hg for each milliequivalent increase in HCO3
The PCO2 also rarely rises above 55 mmHg in compensation for met acid.
The chronic hypoventilation seen in extremly obese patients is often referred to as the
Pickwickian syndrome
or obesity hypoventilation syndrome
compensation in respiratory alkalosis
The predicted relationship of H+ and PCO2 is that 1-mmol decrease in H+ results from each 1-mmHg reduction in PCO2
formula to calculate effective osmolality or tonicity
2 x Na + glucose/18
Normal range: 275-290 mOsm/L
The first step in evaluation of hyponatremia
The first step should include a clinical evaluation of ECF volume status plus comparing measured and calculated plasma osmolalities
Hyperosmostic hyponatremia occurs commonly with
severe hyperglycemia
Each 100 mg/dL increase in plasma glucose above 100 mg/dL decreases serum Na by 1.6 mEq/L
Two important hyponatremic disorders
SIADH
Cerebral salt-wasting syndrome
Both are diagnoses of exclusion after dismissing other causes of hyponatremia
Management of hyponatremia
When the patient presents with severe neurologic symptoms (vomiting, seizures, reduced conscoiusness, cardiorespiratory arrest), the initial treatment includes infusion of 3% HTS
For chronic hyponatremia, the correction rate should not exceed
6 mEq/24 hours
prognosis of severe hypernatremia
Severe hypernatremia (i.e., Na >150 to 160 mEq/L) yiellds a mortality of 75%
Estimation of K+ deficit
(expected srum K - measured K) x ICF (calculated as 40% of total body weight)
