Holmium Laser Settings: Energy, Frequency and Pulse Width Explained

The three holmium laser settings

Pulse energy, measured in joules (J), is the energy of each pulse and mainly controls the size of the fragments: higher energy breaks stones into larger pieces and gives more retropulsion. Frequency, in hertz (Hz), is the number of pulses per second. Pulse width, in microseconds (µs), is how long each pulse lasts; longer pulses generally reduce retropulsion.

Average power is energy multiplied by frequency, so 1 J at 20 Hz gives 20 W. The laser's maximum power is a limit: on MegaPulse 70+ the range is 0.2–5 J, 3–60 Hz and up to 70 W, so not every combination of the maximum values is available at once.

Laser lithotripsy settings: fragmenting, dusting, popcorning

Fragmenting uses relatively high energy at low frequency to split a stone into pieces that are removed with a basket. Dusting uses low energy at high frequency to grind the stone into fine particles. Popcorning uses moderate settings with the fibre inside a calyx so that fragments bounce and break each other. In published practice, commonly quoted starting values for fragmenting are around 0.8–1.5 J at 8–15 Hz, and for dusting roughly 0.2–0.5 J at 40–80 Hz, where the laser allows.

Treat any such range only as an orientation. The surgeon chooses and adjusts the settings during the case based on stone hardness, location, vision and the scope in use. Recommended ranges should come from the laser's instructions for use and the clinical team.

• Fragmenting: higher energy, lower frequency, basket extraction
• Dusting: lower energy, higher frequency, fine particles
• Popcorning: moderate settings in a calyx, fibre held still
• Pulse width: longer for less retropulsion, shorter for faster fragmentation

Pulse width and operating modes on MegaPulse 70+

The MegaPulse 70+ offers Lithotripsy, Soft Tissue and Expert modes. In Expert mode the pulse width can be selected freely from 50 to 1100 µs, so the surgeon can tune the balance between fragmentation efficiency and stone movement. Settings are entered on the foldable 12-inch touch screen and a double-pedal footswitch with standby function controls firing.

Because RFID detects the sterile fibre and its diameter, the device knows which fibre is connected, which helps prevent mismatches between the fibre and the selected parameters. The automatic fibre-port shutter and blast shield add practical safety.

Fibre size and scope compatibility

Fibre diameter changes how the energy is delivered. Smaller fibres, such as those around 200 µm, bend more easily and preserve deflection and irrigation in a flexible ureteroscope. Larger fibres carry more energy per pulse and are used where flexibility matters less. The scope's laser channel defines the maximum: for example the COBRA laser channel is 2.4 Fr and accepts fibres up to 365 µm. See the holmium laser fibre guide for sizes and handling.

Always match fibre, scope channel and sheath, strip and cleave the fibre as the instructions say, and keep the fibre tip clearly visible in the endoscopic image before firing.

Safety checks and next step

Before each case check the fibre connection, test-fire according to the manual, make sure eyewear and signs are in place and set the laser to standby when not firing. Document the final settings used for each procedure, because this builds an internal reference and supports training. Service and calibration are discussed in holmium laser maintenance, and the overview of the technique is in holmium laser lithotripsy.

Beckfinity's specialists can train your team on MegaPulse 70+ operation. Request a quote or consultation to include training in your offer.