Commonly Used Formulas

A-a gradient = [(PB-PH2O) FiO2 - PCO2/R] - PO2 arterial

PB = 760 mmHg; PH2O = 47 mmHg ; R = 0.8 normal Aa gradient <10-15 mmHg (room air)

Arterial oxygen capacity =(Hgb(gm)/100 mL) x 1.36 mL O2/gm Hgb

Arterial O2 content = 1.36(Hgb)(SaO2)+0.003(PaO2)= NL 20 vol%

O2 delivery = CO x arterial O2 content = NL 640-1000 mL O2/min

Cardiac output = HR x stroke volume

Na (mEq) deficit = 0.6 x (wt kg) x (desired [Na] - actual [Na]) SVR = MAP-CVP x 80 = NL 800-1200 dyne/sec/cm2

COL/min

CO L/min

72 (males) x serum creatinine (mg/dL) 85 (females) x serum creatinine (mg/dL)

Creatinine clearance = U creatinine (mg/100 mL) x U vol (mL) _

P creatinine (mg/100 mL) x time (1440 min for 24h)

Normal creatinine clearance = 100-125 mL/min(males), 85-105(females)

Body water deficit (L) = 0.6(weight kg)([measured serum Na]-140) 140

Serum Osmolality = 2 [Na] + BUN + Glucose = 270-290 2.8 18

Na (mEq) deficit = 0.6 x (wt kg)x(desired [Na] - actual [Na])

Fractional excreted Na = U Na/ Serum Na x 100 = NL<1% U creatinine/ Serum creatinine

For each 100 mg/dL increase in glucose, Na decreases by 1.6 mEq/L.

Corrected = measured Ca mg/dL + 0.8 x (4 - albumin g/dL)

Predicted Maximal Heart Rate = 220 - age

PR QRS

Heart rate/min

60 70 80 90 100

Was this article helpful?

0 0
Gaining Weight 101

Gaining Weight 101

Find out why long exhausting workouts may do more harm than good. Most of the body-building workout and diet regimens out there are designed for the guys that gain muscle and fat easily. They focus on eating less and working out more in order to cut the excess fat from their bodies while adding needed muscle tone.

Get My Free Ebook


Post a comment