Respiratory Therapy Normal Values: Reference Guide (2023)

Knowing and understanding the different normal values is essential for making informed clinical decisions as a respiratory therapist.

Because if a patient’s results fall outside of the normal range, it may be indicative of a problem or disease that needs to be investigated further.

Therefore, if you do not know the normal value ranges, how are you supposed to know the best action to take for each patient?

This reference guide will provide you with the most common normal values that are used in the field of respiratory care.

Note: Please keep in mind that what’s considered to be a normal value may vary from one publication to another. However, we have provided the most appropriate ranges to help respiratory therapy students pass the licensure board exams. This information is for educational purposes only.

Vital Signs Normal Values:

• Heart Rate:  60–100 beats/min
• Respiratory Rate:  12–20 breaths/min
• Blood Pressure:  120/80 mmHg
• Body Temperature:  98.6˚F (37˚C)
• Oxygen Saturation (SpO2):  > 93%

ABG Normal Values:

• pH:  7.35–7.45
• PaCO2:  35–45 mmHg
• PaO2:  80–100 mmHg
• HCO3-:  22–26 mEq/L
• BE:  -2 – +2

Normal Lab Values:

• Hemoglobin (Hb):  12–16 gm/dL
• Hematocrit (Hct):  40–50%
• Red Blood Cells:  4–6 millions/mL
• White Blood Cells:  5,000–10,000 millions/mL
• Creatinine:  0.7–1.3 mg/dL
• Blood Urea Nitrogen (BUN):  8–25 mg/dL
• Prothrombin Time:  11–15 seconds
• Platelet Count:  150,000–400,000 units
• Troponin:  < 0.4 ng/mL
• Brain Natriuretic Peptide (BNP):  < 100 pg/mL

Electrolyte Values:

• Sodium (Na+):  135–145 mEq/L
• Chloride (Cl+):  80–100 mEq/L
• Potassium (K+):  3.5–4.5 mEq/L

Ventilatory Values:

• Tidal Volume (VT):  > 5 mL/kg
• Vital Capacity (VC):  65–75 mL/kg
• Minute Ventilation (VE):  5–8 L/min
• Mean Airway Pressure (MAP):  5–10 cmH2O
• Maximum Inspiratory Pressure (MIP):  > -20 cmH2O
• Maximum Expiratory Pressure (MEP):  > +40 cmH2O
• Rapid Shallow Breathing Index (RSBI):  < 100
• Deadspace-to-Tidal-Volume Ratio (VD/VT):  < 60%
• Anatomic Deadspace:  1 mL/pound of IBW
• Cuff Pressure:  25–35 cmH2O
• Capnography:  3–5 %
• Intracranial Pressure (ICP):  5–10 mmHg

Hemodynamic Monitoring Values:

• Cardiac Output:  4–8 L/min
• Central Venous Pressure (CVP):  2–6 mmHg
• Cardiac Index:  2–4 L/min/m2
• Stroke Volume:  50–100 mL/beat
• Pulmonary Artery Pressure (PAP):  25/8 mmHg
• Pulmonary Vascular Resistance (PVR):  200 dynes/sec/cm5
• Systemic Vascular Resistance (SVR):  1400 dynes/sec/cm5
• Pulmonary Capillary Wedge Pressure (PCWP):  5–10 mmHg
• Mean Arterial Pressure (MAP):  93 mmHg
• Urine Output:  40 mL/hour

Oxygenation Normal Values:

• SpO2:  > 93%
• PAO2:  95–100 mmHg on room air
• PaO2/FiO2 Ratio:  > 380
• Shunt (Qs/Qt):  3–5%
• CaO2:  17–20 vol%
• CvO2:  12–16 vol%
• C(a-v)O2:  4–5 vol%
• PetCO2:  25–35 mmHg
• Oxygenation Index (OI):  < 10

Pulmonary Function Testing Normal Values:

• FEV1:  > 80% of predicted
• FEV1/FVC%:  ≥ 70%
• Forced Vital Capacity (FVC):  > 80% of predicted
• Slow Vital Capacity (SVC):  > 80% of predicted
• Airway Resistance (RAW):  0.6–2.4 cmH2O/L/sec
• Diffusing Capacity for Carbon Monoxide (DLCO):  20–25 mL/CO/min/mmHg
• Peak Expiratory Flow Rate (PEFR):  10 L/sec
• Exhaled Carbon Monoxide:  < 7 for nonsmokers

Initial Ventilator Settings Normal Values:

• Tidal Volume:  5–10 mL/kg of the patient’s ideal body weight (IBW)
• Frequency:  10–20 breaths/min.
• FiO2:  30–60% or the FiO2 they were previously on
• Flow Rate:  40–60 L/min
• I:E Ratio:  1:2–1:4
• Sensitivity:  -1 to -2 cmH2O
• PEEP:  4–6 cmH2O

Infant Normal Values:

• Heart Rate:  110–160 beats/min
• Respiratory Rate:  30–60 breaths/min
• Blood Pressure:  60/40 mmHg
• Body Temperature:  98.6˚F (37˚C)
• Oxygen Saturation (SpO2):  > 90%
• Blood Glucose:  > 30 mg/dL
• Gestation Age:  40 weeks
• Apgar Score:  7–10
• Birth Weight:  ≥ 3,000 grams
• L/S Ratio:  ≥ 2:1
• Silverman Anderson Score:  0–1

Final Thoughts

It’s essential for respiratory therapists to learn and understand the different normal values and the appropriate range for each.

Some of the most important types are in the following categories:

• Vital signs
• Arterial blood gases (ABG)
• Lab values
• Electrolytes
• Ventilatory values
• Oxygenation values
• Hemodynamic monitoring
• Pulmonary function testing (PFT)
• Mechanical ventilation

By learning and understanding the normal values for each category, you will be better equipped to provide the best possible care for your patients.

Not to mention, students must know these normal values in order to pass the TMC Exam as well. Hopefully, this guide can make the learning process a little bit easier for you. Thanks for reading!