[Water-jet dissection in parotid surgery--initial clinical results]

Extending the Capability of Using a Waterjet in Surgical Interventions by the Use of Robotics

In waterjet surgery, a thin high-pressure jet is used for dissections and surface abrasion of soft tissue. This selective preparation method preserves nerves and vessels, whereas the surrounding soft tissue is washed away.

OBJECTIVE

The aim of this study is to enhance the application field of this technique by resolving technological limitations.

METHODS

A technical task definition of handling a hand-guided waterjet applicator is derived from the literature. All reported procedures require to follow a trajectory superimposed with an oscillating movement. By introducing a robotic system and a specialized kinematic approach, the limited dexterity of the waterjet applicator is increased. Additionally, the system provides assistance by automatically performing parts of the task.

RESULTS

The method is applied to two different procedures: a minimally invasive dissection and a surface abrasion for open medical treatments. On the basis of experiments with gelatine phantoms, the performance of the method is shown for both procedures.

CONCLUSION

In the minimally invasive use case, the reachability limited by the conventional manual tools is extended by the capabilities of the robotic system. Simultaneously, the handling is simplified by automation of the superimposed oscillation. In the surface abrasion case, a dense coverage of the treated area is achievable. The risk of cross infections could be reduced by spatial separation of patient and staff.

SIGNIFICANCE

Thus, the waterjet technology can be fully integrated into robotic surgery systems and benefit from their inherent abilities.

[In-vitro study on dissection of inflamed synovial tissue by hydro-jet cutting]

Surgical synovectomy is a useful therapeutic option for rheumatoid arthritis patients with ongoing active synovitis despite optimal medical therapy. The present experimental study evaluated the novel, minimally invasive surgical technique of hydro-jet cutting in vitro using synovial biopsies. Depending on the selected water pressure (30-100 bar) it is possible to achieve precise and selective dissection of the synovial membrane. It was found that application of a water jet at 60 bar for 15 s is ideal for dissecting the stratum synoviale from the stratum fibrosum without any alteration of the joint capsule. This finding was confirmed by histological analyses. This novel and precise dissection technique promises to be an excellent alternative to the established techniques of synovectomy in the near future.

[Histomorphologic findings in the facial nerve after water-jet dissection of the parotid gland in dogs]

BACKGROUND

Initial results on the application of the water-jet in a parotidectomy setting in an animal study demonstrate that there are morphologic changes which do, and some which do not, affect the clinial function of the facial nerve due to the different jet sizes and operating pressures used. In a further study the histomorphometric data of the facial nerve dissected by the water-jet should be evaluated and correlated to the different sizes of jet and operating pressures.

MATERIAL AND METHODS

In total, 102 nerves (in 14 beagles) which had been dissected by water-jets of different sizes and operating pressures were evaluated. After an observation period of 21 days, including documentation of the clinical function of the facial nerve, the nerves were dissected. The number of nerve fibers and the diameter of the different nerve fibers were then evaluated.

RESULTS

All nerve fibers dissected with jet sizes of 120 and 150 μm showed an identical cumulative frequency of fiber diameters. All nerve fibers dissected with a water-jet of 200 μm showed morphologic and clinical abnormalities and--in terms of nerve fiber diameters--clear differences to the nerve fibers dissected with 120- or 150-μm jets. Altogether, there is a decrease in fiber diameter along the nerve course.

CONCLUSION

Our data show a shift of larger diameters of the nerve trunk to smaller diameters in the terminal nerve fibers. This phenomenon has not been described in the literature to date and is probably not due to the water-jet. Additionally, our data show that 22% of the original nerve fiber damaged by the water-jet is sufficient to preserve the nerve's clinical function.

First experimental results with a new waterjet dissector: Erbejet 2

BACKGROUND

Waterjet dissection represents a useful technique for many surgical procedures. In this experimental study, the technical features and dissection qualities of the new Erbejet 2 with its new pump and nozzle applicator system are evaluated for its neurosurgical use compared to the established Helix Hydro-Jet.

METHODS

One hundred twenty-six fresh cadaveric pig brains were simultaneously cut with the Helix Hydro-Jet and Erbejet 2. Different pressure levels were applied to cerebral tissue with and without meninges, cerebellum and brainstem. Additionally, dissection characteristics of various cutting media were investigated.

FINDINGS

There was a nearly equal dissection quality at up to 10 bar of both instruments. In contrast to the Helix Hydro-Jet, Erbejet 2 application at higher pressures resulted in an almost linear increase of dissection depth with a small standard deviation. Smoother cutting margins and less foaming were found. Preserved vessels were observed with both devices. Hydroxyaethyl starch led, in contrast to Ringer's solution and isotonic saline solution, to increased dissection width and more foaming.

CONCLUSIONS

The new Erbejet 2 is more precise, with almost linear correlation of pressure and dissection depth compared to the Helix Hydro-Jet. Less foaming and the possible application of various separating media are a considerable advantage. All things considered, the new Erbejet 2 offers more options to enlarge the field of neurosurgical indications for waterjet dissection.

Waterjet dissection of the vestibulocochlear nerve: an experimental study

Object

Waterjet dissection has been shown to protect intracerebral vessels, but no experience exists in applying this modality to the cranial nerves. To evaluate its potential, the authors examined waterjet dissection of the vestibulocochlear nerve in rats.

Methods

Lateral suboccipital craniectomy and microsurgical preparation of the vestibulocochlear nerve were performed in 42 rats. Water pressures of 2–10 bar were applied, and the effect was microscopically evaluated. Auditory brainstem responses (ABRs) were used to define nerve function compared with preoperative values and the healthy contralateral side. The final anatomical preparation documented the morphological and histological effects of waterjet pressure on the nerve.

Results

In using up to 6 bar, the cochlear nerve was preserved in all cases. Eight bar moderately damaged the nerve surface. A 10-bar jet markedly damaged or even completely dissected the nerve. Time course analysis of the ABR demonstrated complete functional nerve preservation up to 6 bar after 6 weeks in all rats. Waterjet dissection with 8 bar was associated with a 60% recovery of ABR. In the 10-bar group, no recovery was seen.

Conclusions

Microsurgical dissection of cranial nerves is possible using waterjet dissection while preserving both morphology and function. The aforementioned jet pressures are known to be effective in neurosurgical treatment of tumors. Thus, waterjet dissection may be useful in skull base surgery including dissection of cranial nerves from tumors. Further studies on this subject are encouraged.

Safety and usefulness of an electric knife during surgery for parotid benign tumor: postoperative facial paresis and its risk factors

CONCLUSION

The incidence of facial nerve paresis was not high compared with previously reported incidences using conventional operative techniques, showing the safety of the use of an electric knife in this operative technique. An electric knife is provided in almost all operating rooms and no special apparatus is necessary for this technique.

BACKGROUND

Since the glandular tissue of the parotid gland is rich in blood flow, safe and accurate protection of the nerve is often made difficult due to bleeding during parotid surgery. Therefore, we developed a technique in which glandular tissue is cut using an electric knife, which is provided in almost all operating rooms.

PATIENTS AND METHODS

In this study, the safety and usefulness of an electric knife in parotid surgery were confirmed by evaluating patients with parotid benign tumor who underwent surgery using an electric knife. The subjects were 135 patients with parotid benign tumors.

RESULTS

Postoperative facial nerve paresis developed in 36 (26.6%) of the 135 patients but was transient in all cases. Depending on the tumor site, transient paresis was observed in 8 of the 13 patients with tumors in the deep lobe but in 28 (22.9%) of the 122 patients with tumors in the superficial lobe. The mean recovery time from facial nerve paresis was 6.1 weeks.

Ossification of the frontal sinus in juvenile minipigs following water jet application

BACKGROUND

Obliteration of the frontal sinus is a generally accepted management for patients with severe craniofacial trauma in whom the sinus cannot be repaired or adequately drained. Effective obliteration requires complete removal of mucosa, sufficient filling of the sinus cavity as well as effective occlusion of the nasofrontal duct. The use of various filling materials for sinus obliteration has been described and include autologous fat, bone, muscle and lyophilized cartilage.

MATERIAL AND METHODS

In order to appreciate the advantages of the water-jet scalpel an animal study in 10 juvenile (4 months old) and 10 adult (18 months) minipigs was performed. In 5 juvenile and 5 adult animals the frontal sinus mucosa was removed using the water jet, while in the others bone curettes were used. No occlusion of the frontonasal duct was carried out and no filling material was implanted. All animals were followed-up for 40 days. After sacrifice, radiological, histological and computerized histomorphometrical examinations were carried out.

RESULTS

Removal of the mucosa from the sinus was simplified when using the water jet. Previous studies have shown that the selected tissue structures were less traumatized when compared with conventional surgical techniques. In young animals (only) and exclusively following the use of a water-jet scalpel osseous occlusion of the frontal sinus was found at follow-up. Histomorphometric findings revealed a significant increase of bone formation in the frontal sinus area of these animals.

CONCLUSION

Based on these experimental results in a small series of juvenile minipigs the water-jet technique is a faster and less traumatic technique (less blood loss) for osteoplastic surgery of the frontal sinus. Further long-term studies are needed to evaluate the possibilities for applying this technique in post-traumatic craniofacial surgery in man.

Water-jet dissection for parenchymal division during hepatectomy

BACKGROUND

High-pressure water-jet dissection was originally developed for industry where ultra-precise cutting and engraving were desirable. This technology has been adapted for medical applications with favorable results, but little is understood about its performance in hepatic resections. Blood loss may be limited by the thin laminar liquid-jet effect that provides precise, controllable, tissue-selective dissection with excellent visualization and minimal trauma to surrounding fibrous structures.

PATIENTS AND METHODS

The efficacy of the Water-jet system for hepatic parenchymal dissection was examined in a consecutive case series of 101 hepatic resections (including 22 living donor transplantation resections) performed over 11 months. Perioperative outcomes, including blood loss, transfusion requirements, complications, and length of stay (LOS), were assessed.

RESULTS

Three-quarters of the cases were major hepatectomies and 22% were cirrhotic. Malignancy was the most common indication (77%). Median operative time was 289 min. Median estimated blood loss (EBL) was 900 ml for all cases, and only 14% of patients had >2000 ml EBL. Furthermore, EBL was 1000 ml for major resections, 775 ml for living donor resections, 600 ml in cirrhotic patients, and 1950 ml for steatotic livers. In all, 14% of patients received heterologous packed red blood cell (PRBC) transfusions for an average of 0.59 units per case. Median LOS was 7 days. EBL, transfusion requirements, and LOS were slightly increased in the major resection cohort. There was one mortality (1%) overall. These results are equivalent to, or better than, those from our contemporary series of resections performed with ultrasonic dissection.

CONCLUSION

Water-jet dissection minimizes large blood volume loss, requirements for transfusion, and complications. This initial experience suggests that this precision tool is safe and effective for hepatic division, and compares favorably to other established methods for hepatic parenchymal transection.

Incision design in implant dentistry based on vascularization of the mucosa

OBJECTIVES

The delivery of an adequate amount of blood to the tissue capillaries for normal functioning of the organ is the primary purpose of the vascular system. Preserving the viability of the soft tissue segment depends on the soft tissue incision being properly designed in order to prevent impairment of the circulation. A knowledge of the course of the vessels as well as of their supply area are crucial to the decision of the incision. The aim of this study was to visualize the course of the arteries using different techniques, to perform macroscopic- and microscopic analyses, and to develop recommendations for incisions in implant dentistry.

MATERIAL AND METHODS

The vascular systems of seven edentulous human cadavers were flushed out and filled with either red-colored rubber bond or Indian ink and formalin mixture. After fixation a macroscopic preparation was performed to reveal the course, distribution and supply area of the major vessels. In the area of the edentulous alveolar ridge specimens of the mucosa were taken and analyzed microscopically.

RESULTS

The analyses revealed the major features of mucosal vascularization. The main course of the supplying arteries is from posterior to anterior, main vessels run parallel to the alveolar ridge in the vestibulum and the crestal area of the edentulous alveolar ridge is covered by a avascular zone with no anastomoses crossing the alveolar ridge.

CONCLUSION

The results suggest midline incisions on the alveolar ridge, marginal incisions in dentated areas, releasing incisions only at the anterior border of the entire incision line, and avoidance of incisions crossing the alveolar ridge.

[Hydrodissection for tonsillectomy. Results of a pilot study--intraoperative blood loss, postoperative pain symptoms and risk of secondary hemorrhage]

BACKGROUND

: Tonsillectomy is one of the most common procedures in head and neck surgery. Various techniques have been developed to reduce the risk of postoperative bleeding and postoperative pain. Water-jet technology has been designed for a gentle dissection of parenchymal organs. We report the results of a first pilot study using the water-jet technique for tonsillectomy.METHODS.: Water-jet-cutting tonsillectomy was compared with conventional blunt dissection tonsillectomy. 60 Patients were stratified in two groups within a preliminary prospective randomised study. Postoperative pain scores, frequency of postoperative bleeding and intraoperative blood loss were documented.RESULTS.: There was no difference in the average duration of the surgical procedure. The intraoperative bloodloss was markedly decreased in water-jet-cutting tonsillectomy. Postoperative bleeding and postoperative pain were decreased in the water-jet-cutting group.CONCLUSION.: The results of this pilot study demonstrate that water-cutting tonsillectomy is associated with less intraoperative bleeding, reduced frequency of postoperative bleeding events and with less postoperative pain.

Blutungen im HNO-Bereich

Otolaryngological bleeding is a highly dangerous condition because it is frequently located close to the upper airways. Additionally, it is often unexpected, especially in children, and can injure important nervous structures of the craniocervical region. Over the years, a broad spectrum of algorithms, innovative technologies and therapeutic options have been developed to reduce the incidence of hemorrhages and improve therapy. Nowadays, close cooperation with an hemostaseologist, anesthesiologist and interventional radiologist is necessary for finding the best strategies for the management of bleeding disorders and vascular lesions. This interdisciplinary dialog, combined with an intimate knowledge of the specific otolaryngological techniques, is the precondition for finding an adequate therapy and fulfilling the increasing medico-judicial and economic requirements. We present an overview of the actual and proved concepts for the management of hemorrhage in order to enable the reader to optimize treatment, to increase safety and comfort for the bleeding patient, and to fulfill the medico-judicial and economic requirements.