Holmium:YAG lithotripsy for large renal and bladder calculi: strategies for efficient lithotripsy

Stones in special situations

There are several special situations in which urinary lithiasis presents management challenges to the urologist. An in-depth knowledge of the pathophysiology, unique anatomy, and treatment options is crucial in order to maintain good health in these patients. In this review, we summarize the current literature on the management of the following scenarios: bladder stones, stones in bowel disease, during pregnancy, in association with renal anomalies, with skeletal deformities, in urinary diversions, and in children.

High-power holmium:yttrium-aluminum-garnet laser for percutaneous treatment of large renal stones

OBJECTIVES

To assess the efficacy and safety of high-power holmium-yttrium-aluminum-garnet (YAG) laser lithotripsy for percutaneous nephrolithotomy in patients with large renal stones.

METHODS

We retrospectively reviewed the charts of 87 patients who underwent 91 percutaneous nephrolithotomy procedures at our hospital from April 2004 to June 2005, during which a holmium-YAG laser with a self-made fiber guider was used for lithotripsy. Of the 91 procedures, 51 were performed with the maximal power output set at 3.0 J in patients with a renal stone size of 3 cm or larger (group 1). The other 40 procedures were performed with the maximal power set at 2.0 J in patients with a renal stone size of less than 3 cm or with ureteral stones (group 2).

RESULTS

The average stone size was 5.4 cm in group 1, and the stone-free rate was 61.4% after a single procedure. The average operation time was 108 minutes in group 1 and 93 minutes in group 2. The average postoperative hospital stay was 5.7 days in group 1 and 5.9 days in group 2. Two patients in group 1 and one in group 2 required blood transfusions after the procedure. Seven patients (13.7%) in group 1 and two (5.0%) in group 2 experienced a urinary tract infection after the procedure. No statistically significant difference in procedure time, postoperative hospital stay, blood transfusion rate, or postoperative urinary tract infection rate was found between the two groups.

CONCLUSIONS

The results of our study have shown that using a high-power holmium-YAG laser is safe and effective in the treatment of large renal stones.

Urinary calculus fragmentation during Ho: YAG and Er:YAG lithotripsy

BACKGROUND AND OBJECTIVES

We tested Ho:YAG and Er:YAG laser ablation of human urinary calculi to determine if Er:YAG is a more efficient lithotripsy device.

STUDY DESIGN/MATERIALS AND METHODS

Ablation efficiency of Ho:YAG and Er:YAG lasers was tested at varying energy settings, ranging from the damage threshold to clinical energy setting associated with Ho:YAG laser. Stones of known composition (calcium oxalate monohydrate (COM), cystine, and uric acid (UA)) were irradiated. Crater width, depth, and ablation volumes were determined using an optical coherence tomography (OCT).

RESULTS

For all stones and energy settings, the Er:YAG laser produced deeper craters and larger ablation volumes than Ho:YAG laser. The Ho:YAG laser created wider craters during the multiple pulse process and the shape of craters was irregular.

CONCLUSIONS

The Er:YAG laser is more efficient than the Ho:YAG laser for lithotripsy. The deeper craters produced by the Er:YAG laser is attributed to the high absorption of energy at its wavelength.

Percutaneous nephrolithotomy with holmium: Yttrium-aluminum-garnet laser and fiber guider—report of 349 cases

OBJECTIVES

To assess the efficacy and safety of holmium:yttrium-aluminum-garnet (YAG) laser lithotripsy for percutaneous nephrolithotomy in a cohort of 349 consecutive procedures.

METHODS

We retrospectively reviewed the charts of 334 patients who had undergone 349 percutaneous nephrolithotomy (PCNL) procedures conducted at our hospital from January 2001 to March 2004 in which the holmium:YAG laser with a self-made fiber guider was used for lithotripsy.

RESULTS

The average patient age was 54.1 years, and the average stone size was 3.3 +/- 1.8 cm. The average operative time was 99 +/- 38 minutes, and the average postoperative hospital stay was 4.0 +/- 2.3 days. The overall stone-free rate was 83.7%. The postoperative urinary tract infection rate was 7.2%. The postoperative transfusion rate was 2.0%. The holmium:YAG laser was effective against all kinds of stones, but sometimes it was time consuming to use the holmium:YAG laser to disintegrate a very large stone. Thirteen PCNLs (3.7%) to treat large complete staghorn stones were performed in combination with a pneumatic lithotriptor. Of the 349 procedures, 152 (43.6%) had bloodless tracts afterward, and all 152 procedures had been performed with the nephrostomy tube-free modification.

CONCLUSIONS

The holmium:YAG laser is an effective and safe lithotriptor for most percutaneous stone surgery. However, in patients with a very large stone burden, the combination of this technology with another, more powerful, intracorporeal lithotriptor may be necessary.

Failure of holmium:yttrium-aluminum-garnet laser lithotripsy in two horses with calculi in the urinary bladder

Holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy was attempted in a mare and a gelding with calculi in the urinary bladder. The procedure was unsuccessful in producing adequate fragmentation of the calculi. In the gelding, pulsed dye laser lithotripsy was subsequently used to fragment the urolith. Manual removal of the urolith via the urethra was performed in the mare.

Update on contact lithotripsy

Despite the development of extracorporeal shockwave lithotripsy, endoscopic stone removal, with or without intracorporeal lithotripsy, is still an effective minimally invasive alternative for special indications. There is no defined all-purpose lithotripsy procedure for contact lithotripsy. The choice of the lithotripsy procedure for endoscopic stone disintegration depends on a number of different factors, the main one being stone localization. Small calibre, flexible probes (electrohydraulic, pneumatic, laser) are especially appropriate for ureterorenoscopy, but the speed of stone disintegration is a limiting factor. In contrast, large calibre rigid probes (ultrasound) are clearly more effective, but are unsuitable in size for flexible ureterorenoscopy. This indicates that the type and size of the endoscope decisively influences the choice of devices for endoscopic stone disintegration. Additional inhibiting factors are the flexibility or the rigidity of the instrument and the diameter of the working channel. It must be noted that total costs are not only calculated on the purchase of the equipment, but must also cover disposable materials.