Respiratory Therapy Normal Values Reference Guide Vector

Respiratory Therapy Normal Values: Reference Guide (2024)

by | Updated: Jun 12, 2024

As a respiratory therapist, it is essential to have a thorough understanding of the normal values used in clinical practice.

These benchmarks are vital for making informed decisions, as deviations from the normal range can indicate potential health issues that may require further investigation.

Without knowledge of these values, determining the appropriate course of action for each patient becomes challenging.

This reference guide lists the most commonly used normal values in respiratory care, providing a reliable resource for respiratory therapists and students. 

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What are Normal Values in Respiratory Care?

Normal values in respiratory care refer to the range of measurements that are typically observed in healthy individuals during tests such as vital signs or lung function assessments. These values serve as benchmarks for assessing, diagnosing, and managing respiratory conditions effectively.

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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
  • Negative Inspiratory Force (NIF):  > -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):  5–15 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:

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

FAQs About Respiratory Therapy Normal Values

Why are Normal Values Important in Respiratory Care?

Normal values are crucial in respiratory care because they serve as a baseline to identify deviations indicative of respiratory dysfunction or disease.

Understanding these values allows respiratory therapists to accurately assess, diagnose, and manage patient care effectively.

What are the Normal NIF and VC Values?

The normal value for negative inspiratory force (NIF) is greater than -20 cmH2O, indicating good respiratory muscle strength. The normal value range for vital capacity (VC) is typically 65–75 mL/kg. 

What is the Normal Respiratory Rate on a Ventilator?

The normal respiratory rate set on a ventilator varies based on the patient’s clinical condition but usually ranges from 12 to 20 breaths per minute for adults.

Adjustments are made according to the patient’s respiratory needs and gas exchange objectives.

What Should the FiO2 and PEEP Be Set At?

The fraction of inspired oxygen (FiO2) and positive end-expiratory pressure (PEEP) settings on a ventilator should be individualized based on the patient’s oxygenation status and lung mechanics.

Typically, FiO2 ranges from 21% to 100%, and PEEP is usually set between 5 to 15 cmH2O, depending on the patient’s needs to maintain adequate oxygenation.

What are the Common Normal Values of the Respiratory System?

Common normal values for the respiratory system include a respiratory rate of 12 to 20 breaths per minute, tidal volume of 6 to 8 mL/kg of ideal body weight, and a PaO2 (arterial oxygen tension) of 80 to 100 mmHg.

Note: These values can vary slightly based on individual factors such as age and overall health.

What is the Normal Minute Ventilation on a Ventilator?

Normal minute ventilation on a ventilator, which is the total volume of air inhaled and exhaled in one minute, typically ranges between 5 to 8 liters per minute for an average adult.

This parameter can be adjusted based on the patient’s metabolic demands and acid-base balance.

What are the Essential Categories for Normal Values in Respiratory Care?

The essential normal value categories for respiratory therapists (and students) include:

Note: These categories collectively provide a comprehensive overview of a patient’s respiratory health and are integral to diagnosing and managing respiratory conditions effectively.

Final Thoughts

Mastering the normal values in respiratory care is crucial for effective patient assessment and treatment. This guide is an invaluable tool for respiratory therapists and students, enabling them to recognize abnormal conditions quickly and respond appropriately.

By staying informed about these benchmarks, respiratory care practitioners can significantly enhance patient care and improve outcomes in respiratory health.

Disclaimer: Please note that normal values can differ across various sources. We have selected ranges that are most relevant for respiratory therapy students preparing for licensure exams. This information is intended solely for educational purposes.

John Landry, BS, RRT

Written by:

John Landry, BS, RRT

John Landry is a registered respiratory therapist from Memphis, TN, and has a bachelor's degree in kinesiology. He enjoys using evidence-based research to help others breathe easier and live a healthier life.


  • Egan’s Fundamentals of Respiratory Care. 11th ed., Mosby, 2016.
  • Clinical Application of Mechanical Ventilation. 4th ed., Cengage Learning, 2013.
  • Respiratory Care Calculations. 4th ed., rtexam, 2018.

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