Buying Guide- Pulse Vs. Continuous

The Basic Difference

Continuous flow oxygen is exactly what it sounds like- oxygen flows out of the device steadily, every second, whether you're inhaling or exhaling. The flow rate is measured in litres per minute
(LPM), and your prescription will look something like "__ LPM continuous".

Pulse dose oxygen delivers a small puff of oxygen each time you start to inhale. The device senses the beginning of each breath and times the delivery to the moment when oxygen actually reaches your lungs. Pulse settings are usually labeled 1 through 5 or 6 and represent calibrated dose volumes, not LPM.

The big advantage of pulse dose: it uses far less oxygen overall, which means much smaller, lighter, and battery-powered devices become possible. That's how portable oxygen concentrators exist at all.

Why Pulse Dose Works for Most Active Patients

When you're upright, alert, and breathing normally, your body inhales for about 1 second and exhales for about 2 seconds. With continuous flow, two-thirds of the oxygen flowing out of the device during exhalation is wasted- it never reaches your lungs.

Pulse dose eliminates that waste by syncing delivery to your inhale. The result: you get a clinically equivalent amount of oxygen using a fraction of the device's output, which means a battery-powered POC can deliver effective therapy at a portable size.

For most ambulatory patients on lower flow rates, modern POCs deliver oxygen saturation outcomes that match continuous flow- confirmed by walking studies and SpO₂ titration. Your physician will determine whether pulse dose is appropriate for your specific case.

When Continuous Flow is Non-Negotiable

  • Overnight Use

    During sleep, breathing slows and becomes shallower. Pulse-dose trigger sensors can miss breaths, leading to under-delivery of oxygen during the hours when consistent therapy matters most. Almost all prescriptions for nighttime oxygen use specify continuous flow.

  • Mouth Breathing

    Pulse-dose POCs detect inhalation through the nasal cannula. If you breathe primarily through your mouth (which is common during sleep, talking, or exertion), the trigger can miss breaths. Continuous flow doesn't depend on detection- it's always flowing.

  • High Flow Rates

    POCs max out at a pulse setting equivalent to roughly 2–3 LPM continuous. If your prescription calls for 4+ LPM, you need a continuous-flow stationary unit.

  • Children and Certain Medical Conditions

    Pediatric patients and patients with very low tidal volumes, severe sleep apnea, or specific cardiopulmonary conditions are often prescribed continuous flow regardless of activity level.

How Pulse Settings Map to LPM

This is the most common patient question. There's no perfect conversion- pulse settings deliver a fixed bolus per breath, so the effective LPM depends on your breathing rate. As a rough guide:

Pulse setting 1: ~0.5 LPM continuous equivalent

Pulse setting 2: ~1 LPM continuous equivalent

Pulse setting 3: ~1.5 LPM continuous equivalent

Pulse setting 4: ~2 LPM continuous equivalent

Pulse setting 5: ~2.5 LPM continuous equivalent

Pulse setting 6: ~3 LPM continuous equivalent

Important Note

These are approximations. A pulse setting that delivers adequate oxygen for one patient may not for another. The only reliable way to confirm a pulse setting is appropriate is an SpO₂ titration during rest, walking, and (if relevant) sleep- done with your physician or respiratory therapist.

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Common Myths

Myth: pulse dose delivers less oxygen than continuous flow

Not true at clinically equivalent settings. Pulse dose times the delivery to your inhale, so a small bolus reaches your lungs efficiently. Continuous flow at low settings wastes most of its output during the exhale phase. The total oxygen reaching the bloodstream is comparable.

Myth: pulse dose isn't real medical-grade oxygen

It's the same medical-grade oxygen (>90% purity)- delivered differently. POCs and stationary concentrators both meet the same Health Canada standards.

Myth: I can use my POC overnight if I just turn thesetting up

No- and this is the most important myth to dispel. Higher pulse settings don't help if the trigger isn't detecting your breaths reliably. If your prescription specifies nighttime use, you need a continuous-flow unit.

How To Know Which YOU Need

Your prescription will tell you. Look for one of three patterns:

  • "Pulse dose at setting X" or "Exertional oxygen" → pulse-dose POC, settings up to 6.
  • "X LPM continuous" → continuous-flow stationary unit.
  • "X LPM during sleep, pulse at exertion" or similar split → you'll need both types of equipment.

If your prescription is ambiguous, call your prescribing physician's office and ask for clarification before purchasing. Or email us at hello@homeoxygensolutions.ca — we can often help interpret what's written and suggest what to confirm with your doctor.

Talk To Your Physician

This guide explains how pulse and continuous flow work. It does not tell you which one you need- only your physician can do that. If you have any uncertainty about your prescription, confirm with your healthcare provider before buying equipment.