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Pointing light at soft tissue: clinical applications 57

If you are treating a patient that seems somehow 7.1.3 Pulsing frequencies
uncomfortable with the LT, check and try the following.
You can deliver your desired dose either with the light
• What are the power output and the power density? always “on” (CW), or by pulsing it with different fre-
You can decrease power density by decreasing power quencies. CW is the fastest way to deliver your treat-
output but also by increasing the spot size of the ment compared to modulated frequency (Hz; light is
beam. Depending on the manufacturer, this can be on/off and the energy is only delivered when it is on)
accomplished by adjusting an integrated “zoom” dial but will also give the patient a warmer sensation. It will
(which moves an internal lens closer to/farther from also increase blood flow more, which is something that
the fiber termination), increasing/decreasing the col- can be worth considering (think for instance about a
limation of the treatment beam or selecting a treat- distal wound with compromised vascularization in that
ment head with a wider diameter, or defocusing by limb). Pulsing the light has shown biological benefits for
increasing the distance to the surface of the patient. wounds. The range of effective pulses described is very
In most cases, this will suffice to improve comfort. broad, though, from 2.5 Hz to 20,000 Hz. [48, 201] You can
Note that if you decrease power, you will decrease the read a detailed discussion about pulsing in Chapter 8.
final amount of energy applied, unless you compen-
sate for this by increasing the treatment time.
7.1.4 How often?

Generally speaking, acute conditions need a more frac-
Compensating for decreased power tioned treatment (lower doses but more often) and
chronic conditions often need higher doses to “wake
Imagine you wanted to deliver 300 J over a certain
area, using 4 W, which would take you 75 seconds. up” the metabolism again, but once some improvement
The patient seems uncomfortable, and one of the is noted they can be treated less often.
things you can do is treat with a lower power, These are examples of general treatment regimes,
such as 2 W. But then, if you were to treat for the but there is some flexibility. The frequency of treatment
same 75 seconds, the delivered amount of energy should be discussed with the owner, since it generally
would drop to 150 J. If you still want to deliver 300 implies several appointments (although maybe not long
J, you should be treating for 150 s. In other words, visits). Particularly for wounds, treatments should be
if you use half the power, you need to double the coordinated with bandage changes as much as possi-
treatment time. ble. More treatment regimes are described under each
condition.

• What is your hand speed? You can’t move faster • Acute conditions: treat daily for 2–3 days, then
than the speed of light, but you can move faster every 48 h for 2–3 more treatments, and then twice
than the speed of heat. So if you find that the surface a week if needed until resolution.
temperature trailing the treatment area is getting • Chronic conditions: treat every 48 h until you see a
warmer, increase the speed of treatment. But make clinical response, then decide if twice a week will be
sure you are getting uniform coverage of the area. enough. In some cases, such as otitis, a weekly dose
• What are the wavelengths used? Darker coats or another maintenance regime is needed for some
will absorb more energy, especially with lower time to prevent relapse.
wavelengths.
• What is the temperature of the patient? A cold 7.2 Wounds and burns
skin has a lower threshold for thermal discomfort
and pain than a warm one. Wound healing is the most documented benefit of LT,
• What area are you treating? Areas with a thinner and since it is such a safe therapy, it should be consid-
skin can be more sensitive. ered in almost every case in which you want to stimu-
• Try decreasing or eliminating the time you work late healing, decrease inflammation, and treat pain.
with continuous wave (CW) (as opposed to pulsed (NOTE: remember, of course, the contraindications
mode), since CW has a more warming effect. such as malignancies.) The analgesic effect on wounds

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