Hi Allen,

Sorry, but I missed your post too, but I’ve been out-of-the-loop for about a month or so anyway.

You handled this like a pro.  Exactly how I wuold have done so using CW diode.

Your insticts and thought processes, and especially your concerns and cautions were right on.

Questions for those in the know:

1) Are my findings consistent with the observations of others?

Yes

2) Are my settings and use of the 810 nm diode here correct?

Yes  (or did you slough any bone? )    

3) What is the diameter of a nutrient canal artery and should we expect the diode laser to effect hemostasis on what I consider a large blood vessel?

OK, now you are getting into some deep laser-tissue interaction thought here…….excellent, I love it.:cool:

Your ability to get hemostasis is dependent on (not necessarily in this order) the “Zone of Irradiance”, blood flow, wavelength, Temporal Emmission Mode (TEM), power and energy density….and the diameter–or cross sectional area you are trying to “poach” or get stasis.

1.  Wavelength–gotta have a near-infrared wavelength (800nm to 1400nm) to get peetration and absorption into deeper structures,  i.e surface absorbing wavelengths like Argon at 477 and 517 nm and CO2 at 10,064 nm won’t do it unless the Creme Brulee effect is sufficient to stop blow flow at the surface

2.  Continuous Wave–Can be though of as an “infinite long pulse duration” since the TEM is CW.

3.  Zone of Irradiance–Very diffuse with CW Near-IR.  You can finess it, as you did, being mindfull of excess exposure to surrounding bone………Better to have a high peak power Near-IR and “long pulse” TEM to better define the cross-section (vessel diameter) in the Z of I, and deliver higher energy densities (intensities) with long refractory “off” times (i.e. 650 microseconds) .

4.  Blood flow–The ultimate heat sink for Near-IR lasers regardless of PD.  By Using 1:50K epi, pressure and time, you gave yourself and the tissue time to slow the blood flow, making it easier to transfer photons (temperature) into the deeper blood vessel bed w/o taking the partially clotting blood away in a sea of flow.

5.  Diameter–Hemostasis in vessel diameter of 600 to 1200 microns is probably what you can achieve, dependent on doing what you did–epi, pressure, time, before Near-IR exposure.

Well done!!  You have demonstrated excellent deductive thinking.  You may now proceed to the next level of sophistication, technology, and tissue mastery!!;) 😉

Bob