Jessica Palmer
4/5/10
Mathematics in Cardiac Care at Piedmont Hospital
Information on how mathematics is used on the cardiac floor at Piedmont Hospital was
obtained from Georgette Rae. She is a cardiac nurse on the floor, as well as the floor educator. She and I
gathered information from various doctors, surgeons, and nurses to explore how they use mathematics
in their workplace.
Each 12 hour shift sets up a proportion to determine the number of nurses needed for the
number of patients currently residing in the unit. If the unit is fully staffed, they need one unit for every
four patients in addition the ancillary staff needed such as secretaries and clinical partners.
Mathematics is used extensively when administering medication. If the drug is intravenous drug,
the nurse has to convert pounds to kilograms (2.2 lbs is 1 kg). The nurses are not allowed to compute
the conversion in their head due to the possibility of error, so they all use calculators. All IV medications
are given based on kilogram weight and Appendix A shows the drug calculation worksheet used
determine drip rates for many different IV drugs. This chart is standard throughout Piedmont Hospital. If
a certain dosage of drug is ordered, the nurses are able to do calculations to determine pump setting
based on the type of drug. Drip rate uses either microgram/kilogram/minute, ml/hour, mcg/min, or
mg/hour.
Nurses either monitor if the pump is set and running or calculate drip rates for a new pump
order. If the patient is currently receiving IV medication, the nurse is responsible for determining the
dosage being infused. If the nurse is setting up the pump, the nurse must first figure out the
concentration needed. She must take the amount of drug and multiply it by a given conversion factor.
Then take the dosage of the drug (for example 2 mcg/kg/min) and multiply it by the patient’s weight in
kilograms, multiply that number by 60, and divide it by the concentration of the drug using another
conversion factor (for example dopamine requires dividing by 1600). Essentially, administering
medication involves a series of conversions.
If a patient is a diabetic, the number of insulin units must be determined by the nurse. The
standard factor is blood sugar minus 100 divided by a correction factor (generally 30). This correction
factor varies by the patient and depends on the severity of their diabetes.
Heparin is used as a blood thinner and commonly seen when a patient has a blood clot, is about
to receive a heart catheterization, or if they need a valve replacement. Heparin is regulated by PTT
(partial prothombin time) which is how well their blood is anti-coagulated (thin). A therapeutic range
governs how Heparin is distributed (see Appendix B) and the nurse increases or decreases the rate
accordingly. To determine therapeutic range, blood is drawn every 6 hours and the Heparin drip is
adjusted accordingly using a nanogram. A nanogram is a preset graph that tells how many units/kg/hour
the dosage needs to be increased or decreased. Ability to read and interpret the Heparin tables and
graphs is essential.
Medication is also given orally and the nurses have to determine dosage based on availability
and doctor’s orders. For example, if the patient requires Coreg and the nurse has 3.125 mg tablets
available, she must determine how many pills the patient needs if ordered to take 6.2 mg twice per day.
Pain scale is assessed numerically on the Wong scale of 1-10. Patients with severe nutritional
needs also require nurses to count their calories and report the data to the dietician. The dietician then
evaluates and plans the patient’s diet accordingly. Mathematics is also used for measuring telemetry
strips that determine patient’s heart rhythms. Telemetry is used to monitor a patient’s heart rhythm and
often seen on ER when the patient flatlines and you hear a long beep. The nurses are responsible for
monitoring the intervals of the EKG to determine heart rate. This helps evaluate if there are any blocks
in the patient’s heart rhythm. Accurate measurement is essential because treatment is based on the
telemetry rhythm.
A simple way mathematics is used through monitoring the intake and output of patients (food
intake and waste removal). This is crucial is patients with congestive heart failure because they have
fluid overload which taxes their lungs and heart. These patients have a restricted intake.
When a patient undergoes heart catheterization, pressures inside the heart are measured using
various instruments. Adequate measurement is necessary to ensure proper treatment of high or low
pressures inside the heart.
For diabetics who have high blood sugar, a Glucotec machine follows a program that uses a
series of calculations to determine drip rate of insulin (see Appendix C). The nurse enters the patient’s
blood sugar into the Glucotec, which calculates the new drip rate of insulin. Some patients have low
blood sugar and a formula is used to determine the amount of glucose they need. 100 minus blood
sugar multiplied by .04 will give the number of milliliters of D50 (a highly concentrated glucose solution).
Mathematics is used in a variety of ways by nurses at Piedmont Hospital, mostly through
measurement and conversions. It is interesting that mental mathematics is not allowed and all nurses
are expected to use calculators in their calculations. This directly contradicts the way mathematics is
taught in many classrooms where calculators are not encouraged. The ability to complete mathematics
mentally is important, but the wide use of calculators in the medical profession makes one wonder if we
are preparing our students with the correct set of skills. Many high schools offer electives that mirror
technical college classes that prepare students for medical careers. Ideally, these elective classes should
concentrate on accurate measurement skills as well as conversion skills.
Appendix A
Appendix B
Appendix C