Ultrasonic Energy Systems in Surgery: How Ultrasonic Shears Seal and Cut

Energy devices let surgeons divide tissue and seal vessels without ties or clips in many situations. Ultrasonic systems do this with vibration rather than electrical current passing through the patient. This article explains how they work and what to look for.

How Ultrasonic Energy Works

An ultrasonic system has three main parts: a generator, a transducer and the instrument itself, which carries the active blade.

1. The generator produces electrical energy at a precise frequency.
2. The transducer converts that energy into mechanical vibration and hands it to the blade.
3. The blade oscillates tens of thousands of times a second against tissue held in the jaw.

This vibration denatures protein and coapts the vessel wall while the same edge divides the tissue. Because the energy is mechanical, no current is transferred to or through the patient, and the tissue is divided by moving it rather than by heating it from the outside in.

The FourZone Energy Range

Fzonic is an ultrasonic system in which the blade oscillates 55,000 times per second. The transducer is a multi-use component rated for more than 150 procedures and built to an industry-standard interface, so it is not stranded by one generation of hardware.

Fzonic Shear focuses on the jaw: a curved, tapered tip dissects in tight planes, a wider aperture takes a bigger bite of tissue when the plane opens up, and higher grasping force keeps tissue where it was placed when the blade begins to move. A revised power algorithm holds the maximum blade temperature lower and shortens the time the hot blade sits against tissue after transection.

See all devices on the Energy Systems page.

Ultrasonic vs Electrosurgical Devices

Both families are widely used, and the choice depends on the procedure and the surgeon’s preference. In general terms:

• Ultrasonic: mechanical energy, no current through the patient, a cut and seal from the same edge, with attention to blade temperature after use.
• Electrosurgical (bipolar): electrical current passes through the tissue between the jaws to seal vessels, usually with a separate blade to cut.

Hospitals often keep both. If the patient has an implanted electronic device, or a nearby energy device is in use, avoiding current through the patient can be a practical advantage, though the surgical team must always follow the manufacturer’s guidance.

What to Look for When Evaluating an Ultrasonic System

• Jaw design: tip shape, aperture and grasping force for the planes you work in.
• Blade temperature behaviour: how quickly it cools and how it affects nearby structures.
• Transducer life: number of procedures, interface standard and sterilisation requirements.
• Generator compatibility: will it work with equipment you already own?
• Ergonomics: weight, button placement and cable handling.
• Cost per case: disposable shears plus the amortised transducer.

Safe Use: A Few General Points

Always follow the instructions for use. Keep the active blade away from tissue and instruments when it is not being used, let it cool before touching other structures, and check the jaw and blade for damage before use.

Where Ultrasonic Energy Is Used

Ultrasonic devices are used in many open and laparoscopic procedures, including general, colorectal, gynaecological, thoracic and head and neck surgery. They are often chosen where a surgeon needs to dissect through vascular tissue and wants to seal and divide in one step.

Benefits Surgeons Look For

• Fewer instrument exchanges. One instrument can dissect, seal and divide.
• Control in tight planes. A fine, tapered tip allows precise dissection.
• Reduced lateral spread concerns. Because the energy is mechanical, heat spread to surrounding tissue is a key design consideration, and manufacturers work to limit it.
• No current through the patient. This is a design point of ultrasonic systems.

Limitations to Keep in Mind

• Vessel size. Devices are rated for a maximum vessel diameter. Larger vessels need a different technique or device.
• Blade heat. The active blade can remain hot after use, so the team must keep it away from tissue and drapes until it has cooled.
• Learning curve. Technique such as the amount of tissue in the jaw and the tension applied influences the quality of the seal.
• Cost. Disposable shears add to the cost of a case, which is why a long-life transducer is attractive.

Looking After the Transducer

The transducer is the part that stays. Follow the manufacturer’s reprocessing and sterilisation instructions, inspect it for damage between cases and keep a record of how many procedures it has been used for. A well-maintained transducer is the foundation of cost-effective ultrasonic surgery.

Related Reading

Energy systems sit alongside staplers, clips and trocars in the operating theatre. See our guide on how to choose a surgical stapler and the access and instrumentation range.

To see an ultrasonic system in action, contact our team.

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