What LPM Oxygen Flow Rate Do I Need? A Respiratory Therapist Explains

By Yash, RRT — Licensed Respiratory Therapist & Owner, MyRespCo

Your oxygen flow rate — measured in liters per minute (LPM) — is one of the most clinically important numbers in your oxygen prescription. It determines which equipment can meet your needs, how long your battery will last, and whether pulse dose or continuous flow is appropriate. Here's what it means and how it's determined.

What Is LPM?

LPM stands for liters per minute — the volume of supplemental oxygen delivered to you each minute. The higher your prescribed LPM, the more oxygen your body requires beyond what room air (21% oxygen) provides.

How Is Your LPM Determined?

Your oxygen flow rate is prescribed by your physician based on blood oxygen saturation testing. The goal is to keep your SpO₂ (blood oxygen saturation measured by pulse oximetry) at or above 90% — typically targeting 92–96% for most patients.

Your physician may prescribe different flow rates for different conditions:

  • At rest: The flow rate that maintains SpO₂ ≥90% when you are sitting or lying still
  • With activity: Often a higher flow rate is needed during walking, climbing stairs, or exercise
  • During sleep: Many patients need more oxygen during sleep due to reduced respiratory drive

Common Flow Rate Ranges and What They Mean

  • 1–2 LPM: Mild hypoxemia. Typically manageable with most portable concentrators on pulse dose settings 1–2.
  • 2–3 LPM: Moderate requirement. Most POCs handle this range well. Inogen G3 (settings 1–5) and G5 (settings 1–6) cover this comfortably.
  • 4–5 LPM: Higher requirement. May push the limits of pulse dose delivery depending on patient response. Continuous flow home concentrator may be needed for sleep or rest.
  • 6+ LPM: High-flow requirement. Portable concentrators cannot meet this need. A home concentrator or compressed oxygen tanks are required.

Pulse Dose vs. LPM — Are They the Same?

Not exactly. A pulse dose setting of “2” on a POC does not deliver exactly 2 LPM of continuous flow — it delivers a calibrated bolus at the start of each breath, optimized for lung gas exchange efficiency. For many patients, pulse dose setting 2 is clinically equivalent to 2 LPM continuous flow — but this varies by individual and should be verified with your physician or RT through oximetry testing.

This is one of the most important reasons to have an RT involved in your equipment selection: matching your actual saturation response to a specific POC setting requires clinical assessment, not guesswork.

How to Know If Your Equipment Is Meeting Your Needs

The simplest way is pulse oximetry monitoring. A pulse oximeter measures your SpO₂ in real time. If your SpO₂ drops below 90% while using your concentrator at the prescribed setting, the device may not be meeting your needs — or the setting may need adjustment.

MyRespCo carries pulse oximeters and can review your oxygen saturation data in an RT Consultation to confirm your equipment is properly matched to your prescription.

Need Help Matching Equipment to Your Prescription?

MyRespCo's $49.99 RT Consultation includes a review of your oxygen prescription, your current equipment setup, and specific recommendations on whether your concentrator meets your clinical needs — including pulse dose saturation verification guidance.

→ Complete POC Buyer's Guide
→ Book an RT Consultation — $49.99
→ Portable vs. Home Oxygen Concentrator