Revised Sept. 22, 1997

Calculator equations:  this is a brief description of each
formula in the medical equations file.  I have my date format
set to mm/dd/yy (in SETUP) and CALC set for 6 decimal places to show the full year on date calculations.

GFR: the first two are male and female versions of the common
   140-age etc formula for estimating GFR from serum Cr.  The
   second two are versions of a formula I use for people with
   higher Cr values (> 2.5 or so).

EDC: enter pt's LMP in the form mm.ddyyyy (ie Dec 4 would be 
   12.041994) to find the EDC (or input the EDC to find the
   LMP, if you want)

Weeks:  these two formulas look at the system date and either
   the LMP or the EDC (choose the formula which uses the date
   you have on hand) to calculate how many weeks pregnant the
   patient is.  They will NOT give you the LMP or EDC if you
   input the weeks (use the next formula to do this).

Ultrasound dating:  this formula is used when you get an OB
   ultrasound report which tells you how many weeks the pt
   was back when she had the U/S done.  USD is the date the
   ultrasound was done and WKS is how many weeks the pt was
   at that time.  The formula looks at the current date and
   determines the EDC.  You can put in today's date for USD
   and the current weeks to figure the EDC.

Serum Osmolality: uses serum Na, K, BUN, & Glc to calculate.

EtOH: estimates EtOH level given the anion gap (assumes the gap
   is due only to the EtOH)

H2O deficit: calculates liters of water needed to dilute a
   hypernatremic pt back to a Na of 140

Corrects measured Na value for hyperglycemia

Na Deficit: calculates the meq of Na needed to bring a hypo-
   natremic pt back up to Na of 135

Correct measured K+ for acidosis (use pH from ABG)

Correct measured Ca for low serum albumin

HCO3 deficit: calculates meq of bicarbonate needed to bring
   serum HCO3 (CO2 on chem-6) to 12.  I use this for acidotic
   children with dehydration.  I give those with very low
   bicarb levels enough to get them back up to 12 over the
   first 8-12 hours of rehydration and let the pt correct from
   there with continued hydration.

Correct measured drug concentration for low serum albumin.
   This is for highly protein bound drugs like Dilantin.

CrCl actual: calculates actual Creatinine Clearence from
   results of 24hr urine collection (urine Volume in ml,
   and urine and serum Cr measurements) results in ml/min

Temperature: converts Fahrenheit to Celcius (left over from
   my HP95 which didn't have this function built in).

Anion Gap: uses Na, K, Cl, & HCO3; normal 8-13

Alveola to arterial gradient

Body surface area using wt in Kg and Ht in cm.  Two different
   formulas, both give similar results.

Ideal body weight: uses hight in inches (you can convert right
   on the calc line as you are entering data into the formula)
   and returns wt in Kg.

Mean arterial pressure, given Systolic and Diastolic BP

Sickle PRBC: calculates how many units of packed RBC's to
   transfuse to bring the pt's hemoglobin up to 10.  I use
   this in children with sickle cell who have an indication
   for transfusion.  The ccPerKg factor is 65 for adults,
   and 80 for infants with children in between.

ET tube size: estimates endotracheal tube size given age of
   child

Henderson Hasselbach equation we all loved from college chem.

Nitrogen balance equation

Formula to calculate the patient's average glucose based on their Hemoglobin A1c value

Body Mass Index calculation
