Suction machines, catheters and depth

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Learn about the different parts of a suction machine, how to use one and how to identify the correct suction depth for your child.

Key points

  • All types of suctioning require a suction machine.
  • Portable suction machines are best so that you can suction on the go, when you are away from home.
  • Use pre-measured suction catheters to make sure you are at the correct suction depth.

Suction machines

No matter what type of suctioning you perform, you will need to use a suction machine. A back up manual suction setup is helpful to have on hand in case the powered suction machine malfunctions.

There are portable suction machines that use batteries and stationary suction machines that plug into an electrical outlet. It is recommended that your suction machine is portable so that you can “suction on the go” when you are away from home.

Many brands of suction machines are available. Your local medical supplies vendor will help you decide which one is best for your child. The vendor will also teach you how to use the suction machine you decide to buy. When purchasing your suction machine, be sure to ask about the suction machine’s warranty.

Parts of a suction machineA suction machine with labels for the canister, tubing, filter, pressure gauge and regulator, battery level, power light, AC plug and on and off switch

All suction machines have:

  • an outlet filter
  • canister
  • pressure display panel or gauge
  • pressure regulator (allows you to control the pressure)
  • AC plug and/or a battery and charger
  • a power switch


Between suctions, remember to plug the portable suction machine into an AC wall outlet so that it will charge and be ready to use when you need it next.

  • When using the machine in AC power mode, the on/off light will appear.
  • When using the machine in battery mode, the on/off switch will not light up.

The battery on a fully-charged suction machine should last about 45 minutes, but this will vary from machine to machine. Aim to use the battery for only 30 minutes at a time so that it can re-charge more quickly.

How do I know the right size catheter for my child or how far I can suction?

In general, the recommended suction catheter sizes and suction depth depend on the size of your child and the type of suctioning being done. As a general guideline, for nasal, nasopharyngeal and oropharyngeal suctioning, the size of the suction catheter should not be any larger than half the size of your child’s nostril.

Identifying the correct suction depth

  • For nasal suctioning measure from your child’s nostril to the middle of the nose.
  • For nasopharyngeal and oropharyngeal suctioning measure from your child’s nostril to the tip of the earlobe.
  • Record the suction depth on the tape measure or make note of the number marking on the catheter and record this number.
  • Attach the tape measure to the cot/bedside/suction machine for future use.
Measuring the length of suction catheters
Use this illustration to measure the length of suction catheter needed for nasopharyngeal and oropharyngeal suctioning.
Correct suctioning depths Correct suction depths shown for nasal, nasopharyngeal and oropharyngeal suctioning
Use the pre-measured suction catheters (where available) to make sure you are suctioning at the correct depth.

Use pre-measured suction catheters (where available) to ensure accurate suction depth.

Your child’s health-care provider will review with you what type of suction your child needs, the suction catheter your child needs, how far to insert the suction catheter and which pressure setting to use for the suction machine.

Suction catheter size:     
Depth of suction catheter insertion for suctioning:   
Suction machine pressure setting (mmHg):     
Last updated: February 20th 2020