The 150 ml Drip Chamber in an EVD Set: Its Role

What the drip chamber does in an EVD set: how it shows drainage flow, what its 150 ml capacity means and how it works with the scale and the 800 ml bag.

The drip chamber is the part of an EVD set where drainage can be seen and from which fluid passes into the collection bag. DESU's EVD sets, the EVD-010 and EVD-020 systems, both use a 150 ml drip chamber that supports monitoring of drainage flow and transfers fluid to an 800 ml air-filtered drainage bag.

Key takeaways

• The drip chamber lets staff see drainage flow and passes the fluid on to the drainage bag.
• Both EVD-010 and EVD-020 have a 150 ml drip chamber and an 800 ml air-filtered bag.
• 150 ml is a capacity, not a target or a limit on how much CSF should drain.
• Drainage height and the emptying routine are set by the clinical team and hospital protocol.

Where does the drip chamber sit in an EVD set?

External drainage is a chain of parts, and the chamber sits near the end of it. In a DESU system, CSF follows this path:

• The catheter takes CSF from the patient.
• The 60 cm reinforced connection line, with its locking mechanism, connects the components of the drainage system.
• The drip chamber receives the fluid and lets staff watch it arrive.
• The 800 ml drainage bag collects it.

Alongside this path are the 30 cm measuring scale, with mmHg and cmH₂O markings, two three-way connectors and a hydrophobic filter. The scale supports CSF pressure monitoring and drainage-level adjustment.

Why does the height of the chamber matter?

A standard EVD is a gravity system with no pump. In a typical set-up, the chamber is positioned on the scale at a height the physician orders, relative to a reference point on the patient. CSF flows into it only when the pressure in the head is greater than that height represents. So the chamber's position works as a threshold, and the volume drained depends on the patient, not on the system.

The chamber looks like a simple plastic container, but its position is the setting. The steps for levelling and zeroing are covered in EVD zeroing and levelling explained.

Why does CSF drip into a chamber instead of running straight to a bag?

The name describes the function. Fluid falls through an air space in the chamber instead of running in an unbroken column down to the bag. In a gravity drainage system, that gap has two effects.

• It separates the set level from what happens below. Without a break in the column, fluid already in the tubing under the set level could pull on the fluid above it, as in a siphon.
• It makes flow visible. Separate drops can be seen, so staff can tell at a glance whether fluid is arriving.

A chamber with an air space also needs to stay open to air, or it cannot drain freely. That is the usual purpose of a filter in the vent of a gravity drainage system: air can move while liquid and contaminants are held back. The DESU system has a hydrophobic filter as a core component and an air filter on the bag. Handling follows the instructions for use.

What can staff see at the chamber?

The chamber supports visual monitoring of drainage flow. It is the first place at the bedside where a nurse sees CSF, and three things can be observed there.

• Whether fluid is arriving at all. A chamber that has stopped filling is a reason to check the line and the set-up according to unit protocol.
• How quickly it is arriving, which the team judges against the drainage order.
• What the fluid looks like, since a change in colour or clarity is something nurses report.

None of these observations is a diagnosis. What they mean, and what to do about them, is for the clinical team to decide.

What does 150 ml mean?

150 ml is the capacity of the chamber. It is not a recommended drainage volume or a limit on what a patient should drain. It tells a unit how much fluid the chamber can hold before it needs to be passed on to the bag.

The chamber and the bag do different jobs. The chamber is the working volume, close to the scale, where fluid is seen. The 800 ml bag is the storage volume. How often a unit empties the chamber is set by its own protocol, and the article on EVD drainage bag sizing and change-out looks at that side of the question.

Buyers and nurse educators who want to see how the chamber is marked, fixed on the scale and emptied into the bag can ask for the instructions for use or a sample.

Is the chamber the same in EVD-010 and EVD-020?

Yes. The two systems match on these specifications:

The EVD-010 Series is built around a 31 cm ventricular catheter. The EVD-020 Series can be used with a ventricular or a lumbar catheter. With the lumbar drainage catheter kit, the fluid comes from a different place, but the chamber does the same job.

Can the drainage bag be replaced separately?

Yes. The 800 ml bag is supplied separately in packs of 1, 5 and 10, under codes ENDS-B1, ENDS-B5 and ENDS-B10.

Talk to a DESU product specialist

For the instructions for use, sample units or configuration codes for your unit, write to sales@desu.tr, use the contact page or request a quote.

Frequently asked questions

Does a larger drip chamber drain more CSF?

No. Capacity only sets how much fluid the chamber can hold. In a gravity system, drainage depends on pressure relative to the height the chamber is set at.

Is the drip chamber used in lumbar drainage too?

Yes. The EVD-020 system is used with a ventricular or a lumbar catheter, and it has the same 150 ml drip chamber in both configurations.

Can the drip chamber be ordered as a separate item?

The 800 ml drainage bag has its own codes, but the drip chamber does not. A DESU product specialist can advise on replacement options.

Related standards

• ISO 13485: Medical devices — Quality management systems
• ISO 10993 series: Biological evaluation of medical devices