What is the difference between a Pulse and a Continuous Flow

We are often asked the difference between between an “on demand”, also known as “pulse flow” versus “continuous flow” oxygen delivery to a patient by nasal cannula.
Portable oxygen flow can be delivered to a patient by two different methods continuous flow or pulse delivery pulse is also known as on demand delivery or conserving technology.

PULSE FLOW. All of the small POC’s (Portable Oxygen Concentrator) use this type of flow. Manufacturers run slick ads on television showing the very small machines, but there is a large patient population who can not use this technology.

When using a portable with pulse delivery, this means that you only receive the oxygen every time you begin to take a breath. There are conserving regulators that are used on oxygen cylinders that give you a dose of oxygen each time you breathe. If it was very quiet and someone was near your nose each time you inspire they could actually hear it give you a puff of oxygen as you breath in.

CONTINUOUS FLOW: This is typically a "at home" or "static" device using a wall plug. This device is giving you the oxygen in a constant or continuous flow meaning if you took off the nasal cannula and put it in a glass of water it would bubble like an aquarium.

Who should use a Pulse Delivery ?

What type of patient can use Pulse delivery and what type of patient should absolutely never use Pulse delivery?

Pulse delivery is designed for adults and not children and adults breathe an average 12 to 18 times a minute. The machines are designed to operate on a setting based on 15 to 18 breaths per minute as equivalent to the litre flow and relationship to the setting so for example the setting of two on pulse at 15 to 18 breaths a minute could be equal to 2 Litre per minute of flow based on the volume of each dose.
If the adult is a mouth breather meaning perhaps they have a nasal septal defect and cannot breathe normally through their nose and typically are always only breathing through their mouth, this type of patient is not a candidate for pulse delivery however most adults that breathe normally through their nose tend to do quite well with a pulse or on demand delivery system. Whether it be a regulator on a cylinder that will extend the length of time the cylinder will last 2 to 4 times longer or the use of one of the very small POC‘s such as the Inogen G3 it is important that the proper patient is using the proper device.

Children breathe much faster than adults, therefore pulse or on demand flow technology should not be used with a child. The child will breathe faster than the equipment can make the oxygen therefore putting the equipment into alarm and they are not designed for use by children.

Sleeping: When we sleep it is very natural for us to become a mouth breather at some point during our sleep. It is not recommended by most physicians to use pulse delivery when you were sleeping.