1
What equations are commonly used on the wards?
Anion Gap
Na − (Cl + HCO 3 )
Normal = 10–14
FeNa
FENa = [(U Na × S Cr )/(S Na × U cr )] × 100
U = urine
S = serum
Maintenance Fluids
Per hour, a person needs:
4 mL/kg for the first 10 kg (0–10 kg)
2 mL/kg for the next 10 kg (10–20 kg)
1 mL/kg for the remaining kg (>20 kg)
Creatinine Clearance
[(140 − age) × (weight in kg)]/(72 × S Cr ) for males. Multiply by 0.85 for females.
Note: This estimate is useful only if serum creatinine is not changing rapidly.
Alveolar-arterial Gradient
[713 × (FIO 2 ) − (PaCO 2 /0.8)] − PaO 2
Normal <20
Mean Arterial Pressure (MAP)
(2/3) × diastolic + (1/3) × systolic
Osmolality (estimated)
(2 × Na) + (glucose/18) + (BUN/2.8)
Normal = 290 mOsm
2
What is APGAR scoring?
The APGAR scoring examination is used to describe the condition of newborn infants. It is determined at 1 and 5 minutes after birth. The score is the sum of five assessments, ranging from 0 (worst) to 10 (best).
| A ppearance | A ctivity |
| 2 = Entire body pink | 2 = Active movement |
| 1 = Pink body with blue extremities | 1 = Some movement |
| 0 = Entire body blue/pale | 0 = Limp |
| P ulse | R espirations |
| 2 = >100 bpm | 2 = Strong, crying |
| 1 = <100 bpm | 1 = Slow, irregular |
| 0 = Absent | 0 = Absent |
| G rimace | |
| 2 = Cough or vigorous cry | |
| 1 = Grimace or slight cry | |
| 0 = No response |
3
What composes the various intravenous fluids?
| Fluid | Na (mEq/L) | K (mEq/L) | Cl (mEq/L) | HCO 3 (mEq/L) | Ca (mEq/L) | Calories (kcal/L) | Glucose (g/L) |
|---|---|---|---|---|---|---|---|
| ½ NS | 77 | — | 77 | — | — | — | — |
| NS | 154 | — | 154 | — | — | — | — |
| D5W | — | — | — | — | — | 170 | 50 |
| D10W | — | — | — | — | — | 340 | 100 |
| LR | 130 | 4 | 109 | 28 | 3 | 9 | — |
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