and Gordon Muir1
Department of Urology, Kings College Hospital, Denmark Hill, Brixton, London, SE5 9RS, UK
The introduction of lasers to urological surgical practice has resulted in significant improvements in patient care. This has been demonstrated in the management of stones and also in the treatment of prostatic disease. Urology is a rapidly evolving specialty and laser surgery is at the forefront. Laser surgery for bladder outflow obstruction can offer significant benefits to the patient and to the hospital whilst offering similar or superior outcomes to TURP or open prostatectomy.
Lasers have been used to perform bladder neck surgery since the 1980s and gained popularity in the 1990s. They rely on the delivery of light energy to the tissue resulting in absorption by the tissue, transformation into heat, protein denaturation, vascular shrinkage, cellular dehydration and eventually tissue vaporisation at 300° centigrade. The primary effect used in prostate and bladder neck surgery is the thermal effect , rather than the other effects (mechanical, photochemical and tissue welding). Different lasers have differing tissue effects, and this can also vary with the power and energy concentration.
Lasers maintain a number of advantages over previous transurethral electrosurgery namely, less bleeding, lower irrigation absorbtion, the use of saline irrigation rather than glycine and a much shorter period without a catheter post operatively (or indeed no catheter). These factors allow some laser operations to be performed within a day case setting. These significant advantages mean that the surgery carries a lower risk in terms of morbidity and mortality when compared to TURP. Patients who may otherwise have been deemed too unfit for standard TUR surgery may also now be considered as suitable candidates for surgery.
Long term catheterisation causes significant morbidity and the ability to operate on a population of catheterised men who were previously considered unsuitable for surgical intervention may have an important impact in the reduction of this catheter related morbidity.
In a health care system such as the National Health Service (NHS) where major financial restraints exist, day surgery offers major cost saving benefits . Most patients undergoing elective TURP surgery undergo their operations as an inpatient and will spend two to three nights in hospital—for retention patient stays may be longer. In contrast, laser surgery offers a day surgery or overnight experience and can often offer transient post operative catheterisation or a shorter post operative period with a catheter with a trial without catheter (TWOC) as an outpatient.
The laser was developed in the mid twentieth century, the first laser built by Theodore H. Maiman at Hughes research lab in 1960. Charles Townes at Columbia University developed the maser, the precursor to the laser. Townes and Bell published a key theoretical paper in 1958 and Maiman published his paper describing the operation of the first laser.
“Laser” is an acronym, ‘light amplification by stimulated emission of radiation’.
The first medical use of lasers was in 1963 by Leon Goldman, a dermatologist in the U.S. He used the laser to treat skin conditions, including melanoma as well as pioneering its use for tattoo removal.
The removal of prostatic tissue using lasers was originally described in 1986 but it was not until 1990 that the introduction of a side-firing Nd-YAG laser (neodymium-doped yttrium aluminium garnet; Nd:Y3Al5O12) led to more widespread use of the laser in the treatment of bladder outflow obstruction.
Lasers rely on the principle of ‘stimulated emission’ first proposed by Einstein in 1917. This is the idea that a photon of a specific frequency can interact with an atomic electron and cause it to drop to a lower energy level. The energy released by this electron goes on to released. The liberated energy transfers to the electromagnetic field, creating a new photon with a phase, frequency, polarisation, and direction of travel that are all identical to the photons of the incident wave. In normal media at thermal equilibrium, absorption exceeds stimulated emission because there are more electrons in the lower energy states than in the higher energy states. However, when a population inversion is present the rate of stimulated emission exceeds that of absorption, and a net optical amplification can be achieved. Such a gain medium, along with an optical resonator, is at the heart of a laser or maser.