Kim Brackett

A comparison using the Nd-YAG laser, an ultrasonic surgical aspirator, or blunt dissection

Before gaining wide acceptance, possible surgical tools should be compared with the standard ones. This study, therefore, compared the Nd-YAG laser and the CUSA with the standard blunt dissection technique for liver resection in 24 dogs (8 in each group). Using a noncontact technique, the Nd-YAG laser was used for cutting as well as coagulation. The Nd-YAG laser or the CUSA reduced the resection time, with the laser being the faster of the two, and was accompanied by a probable but not significant decrease in perioperative blood loss. The CUSA delineated the blood vessels and bile ducts and gave superior control. It also caused significantly less tissue damage on light and electron microscopic examination than the other two methods. Cultures taken 1 week after operation showed that the risk of bacterial infection correlated well with the extent of tissue necrosis and was significantly greater after use of the Nd-YAG laser than after use of the CUSA. The numbers of animals are small and the conclusions should be tempered by caution, but it appears that the CUSA, but not the Nd-YAG laser, may improve the results of elective liver resection.

Ultrastructure of early development of acute pancreatitis in the rat

This study was undertaken to define the earliest ultrastructural changes appearing in the exocrine pancreas and its vasculature during the development of experimental acute pancreatitis induced by the closed duodenal loop technique. Experimental and shamoperated rats were killed at hourly intervals up to 4 hr and at 6 hr postoperatively. Focal acinar cell response included appearance of vacuoles containing uncondensed or partially condensed secretory product, and some rearrangement and dilatation of the rough endoplasmic reticulum within 1 hr. Mild edema was observed and damage to the vascular endothelium developed by 2 hr. At 4 hr focal hemorrhage and a slight inflammatory cell infiltrate was noted which was more prominent at 6 hr. The lack of a correspondence between areas of acinar cell and of vascular abnormalities suggests that factors other than increased secretory back-pressure are involved in the early development of this model of acute pancreatitis.

Splenic resection with the contact Nd:YAG laser system

Splenic resection in the dog was proven to have decreased blood loss (52%), decreased operating time (44%), and decreased surgical manipulation using the SLT Contact Nd:YAG Laser System with the synthetic sapphire probe, as compared with the noncontact CO2 laser. Tissue damage and hematologic changes were minimal and equivalent in both laser systems. The overall ease of use and operating technique was subjectively better with the contact Nd:YAG laser, and the danger of scattered and reflective beam damage was eliminated. The contact Nd:YAG laser with the synthetic sapphire probes offers a significant advantage over the noncontact CO2 laser in the resection of splenic tissue. Future applications in pediatric surgery now need to be evaluated.

Proximal pancreatectomy: a comparison of electrocautery and contact and noncontact Nd:YAG laser techniques in the dog.

Proximal pancreatectomy with duodenal preservation is technically difficult. It has often been performed experimentally in pancreatic transplantation studies. Preservation of the pancreaticoduodenal vessels and duodenum provides an excellent method of testing various operative techniques in pancreatic surgery which may lead to further clinical applications. The present study has compared the conventional noncontact Nd:YAG laser technique with electrocautery and a new contact Nd:YAG laser technique for proximal pancreatectomy. There were five dogs in each group, and the pancreatic duct was left open to drain into the abdominal cavity after pancreatic transection in all of the animals. Resection with the contact laser caused significantly less blood loss (109 +/- 74 ml) than the noncontact laser (228 +/- 81 ml), (p less than 0.05). A greater number of ligatures were used in the noncontact laser group (11 +/- 3 ligatures) as compared with the electrocautery group (2.2 +/- 1.6 ligatures) and the contact laser group (5.2 +/- 2.8 ligatures), (p less than 0.005). Noncontact laser and electrocautery resection techniques resulted in necrotizing pancreatitis and death in two animals. The new contact laser system provides a safe and effective method of performing pancreatic surgery.

Splenic Resection with the SLT Contact Nd:YAG Laser System®: A Comparison of Contact Nd:YAG with the CO2 Laser

The spleen has important physiologic and immunologic functions and should be surgically conserved whenever possible. Morris and Bullock1 in 1919 showed that splenectomized rats had an increased susceptibility to infection and in 1952, King and Shumacker2 reported a significant increase in fatal aepsis in children following splenectomy. Subsequent studies have confirmed an increased morbidity and mortality of 50 to 200 times normal in patients of all ages, at various times following splenic removal, and have therefore advocated surgical alternatives to total splenectomy.3–9 Splenic repair with adequate hemostasis is difficult due to the highly vascular and extremely fragile splenic tissue.

Liver Resection with the Nd: YAG Laser: A Comparison of a New Contact Probe, the Laser Scalpel, with the Conventional Non-Contact Method

The technique of liver resection is well standardized, but recent reports still show that major liver resection is associated with an operative mortality of 4–20%. We recently compared the Nd:YAG laser and the Cavitron ultrasonic surgical aspirator (CUSA) with the routine blunt dissection method of performing a liver resection (1). The non-contact Nd:YAG laser resulted in a significant reduction in operating time compared to the other two methods (p<0.01), decreased the perioperative blood loss, but caused more extensive tissue necrosis. The study compares the conventional non-contact with the new contact artificial sapphire designed as a laser scalpel (2) in performing a liver resection with the Nd:YAG laser. Assessment included technical feasibility, duration of resection, tissue changes, adhesions, smoke production and blood loss.

In vitro and in vivo technique for assessing vagus nerve regeneration after parietal cell vagotomy in the rat

This study determined if the vagus nerve can regenerate and/or reinnervate the gastric parietal cell mass after parietal cell vagotomy (PCV) and examines tests for assessing vagus nerve regeneration in rats. Microscopic dissection of the neurovascular bundle allowed the vagus nerve to be divided at the gastric body with preservation of the antropyloric nerve and gastric vasculature. Gastric secretory tests were performed under basal and stimulated conditions using secretagogues and insulin hypoglycemia. The candidate hormone, pancreatic polypeptide, was measured in plasma following a mixed meal, insulin hypoglycemia and i.v. secretin. Rats were killed weekly for 9 weeks and the vagal nerve distribution examined by both light and electron microscopy. Stimulated gastric acid output fell from 164 to 26 mumol/h immediately after operation (P less than 0.001). One week following PCV, the nerves were swollen with fibroblast infiltration and collagen around axon groups showed degeneration. By the third week after PCV, the axons were more densely packed with neurofilaments and acid output had increased to 183 mumol/h. In the fourth and fifth weeks, the enlarged Schwann cell processes had more axons and acid output rose to 262 mumol/h. By the seventh week, both large and small axons were identified and the acid output was 93% higher than the preoperative level (P less than 0.001). PCV and antrectomy also was followed by reinnervation of the gastric mucosa. Pancreatic polypeptide concentration in plasma was virtually unchanged following ingestion of food, insulin hypoglycemia or secretin. In rats, following PCV, gastric secretory tests and electron microscopy seem to be the most reliable methods of assessing vagus nerve regeneration.

Effects of Non-Contact Nd: YAG Laser Photoradiation in Intra-Adominal Tissues

The Nd: YAG laser in the gastrointestinal tract produces hemostasis and tumor vaporization (1–5,7–9,12). The ability of laser as a cutting tool, without bleeding, when used in the resection of vascularized solid organs like liver, spleen and pancreas is promising. This paper studies the histological effects following non-contact Nd: YAG laser photoradiation in these intra-abdominal organs including tissue necrosis and the healing process using various laser powers and duration.