Respiratory Care Formulas

a. Calculate the average VT for a patient with a Ve =8.24 L/m and a RR= 16 bpm?

Use (VT = Ve/RR)

b. Convert 175 lbs. to kilograms.

Use (1 kg. = 2.2 lb) 

c.  Given a gas mixture of 70% Helium and 30% Oxygen that is running at a flow rate of 5 lpm (liters per minute) on an oxygen flow meter. What is the actual flow rate of this gas mixture? Use (Actual flow = Heliox factor x flow rate) The heliox factor for a 70% He/30% O2 mixture is 1.6 and the heliox factor for an 80% He/20% O2 mixture is 1.8) 

d. Calculate actual flow rate of an 80% He/20% O2 gas mixture running at 5 Lpm on an oxygen flow meter?

(Actual flow = Heliox factor x flow rate) The heliox factor for a 70% He/30% O2 mixture is 1.6 and the heliox factor for an 80% He/20% O2 mixture is 1.8) 

e. Calculate the cardiac output for a patient that has a heart rate of 90 beats/min and a stroke volume of 50 ml. Express answer in Lpm (Cardiac output or QT = HR x SV (ml)) 

f. Given PaCO2= 30 mm Hg and PECO2= 21 mmHg What is the Vd/VT ratio. Hint: Answer must be expressed in percent (Vd/VT = (PaCO2 - PECO2)/PaCO2) 

g. Given PaCO2= 35 mmHg and PECO2= 20 mmHg PaO2= 80mmHg PH 7.45 What is the Vd/VT ratio? Hint: Answer must be expressed in percent.

h. A patient has a recorded body temperature of 109° F. What is this temperature in degrees Celsius? (to convert from ºF to ?C ,use (?F - 32) /1.8)

i. What is the minute ventilation of a patient breathing at the rate of 15 bpm, who weighs 75Kg and has a VT of 500 ml? Express your answer in both ml/min and liters/min

(minute ventilation or Ve = f (breaths per min) x VT (tidal volume in ml) 

j.  Hospital (A) has a total of 18 registered respiratory therapist (RRT) and 12 certified respiratory therapist (CRT). Hospital (B) has 12 registered respiratory therapist (RRT) and 6 certified respiratory therapist (CRT).

What is the ratio of RRT's to CRT's in Hospital A compared to Hospital B?