Monopolar Radiofrequency Energy Research Articles

General anaesthesia and deep sedation for monopolar pulsed field ablation using a lattice-tip catheter combined with a novel three-dimensional mapping system.

A novel three-dimensional mapping platform combined with a lattice-tip catheter that can toggle between monopolar pulsed field ablation (PFA) and radiofrequency energy delivery was recently launched. So far, the system was predominantly applied in general anaesthesia (GA), not in deep sedation. Patients with symptomatic paroxysmal or persistent atrial fibrillation (AF) were enrolled, and pulmonary vein isolation (PVI) and ablation of additional linear lesion sets were performed either in GA or in deep sedation. Pulsed field ablation was applied exclusively to perform ipsilateral PVI. A total of 63 patients (35% female, 75% persistent AF, mean age 64 ± 9 years) were included in the analysis with 23 patients treated in GA and 40 patients in deep sedation. Acute efficacy was comparable in both groups with a PVI rate of 100%. Additional 74 lesion sets were performed in the total cohort. Mean procedure and lab occupancy time in the GA and deep sedation group was 96 ± 24 min vs. 100 ± 23 min (P = 0.52) and 165 ± 40 min vs. 131 ± 35 min (P = 0.0008). Mean dose area product was 489 (216;1093) vs. 452 (272;882) cGycm2 in the GA and the deep sedation group (P = 0.82). There was one conversion from deep sedation to GA. There were no map shifts observed in any group. Pericardial tamponade occurred in one patient of the deep sedation group. The use of a novel ablation platform in conjunction with a lattice-tip catheter in deep sedation is feasible, effective, and associated with significantly shorter lab occupancy time when compared with GA.

Monopolar Radiofrequency Energy Delivered by a Conductive Endovascular Basket or Guidewire Leads to Thermal Occlusion in a Swine Model

PurposeTo assess the feasibility of inducing vascular occlusion by application of radiofrequency (RF) energy via conductive endovascular wires or baskets. Materials and MethodsA retrievable nitinol basket and stainless steel guidewire with a platinum tip were evaluated as conductors for endovascular application of RF energy. Tissue-mimicking thermochromic gel phantoms that change color with heating were cast with 2-, 5-, and 7-mm-diameter lumens and filled with 37 oC saline. After ablation, the phantoms were sectioned, and the thermal footprints were evaluated. Six castrated male domestic swine underwent endovascular ablation using the basket in iliac arteries and guidewires in renal arteries. Post-procedural angiography was performed, and postmortem arterial segments were resected for histopathologic analysis. ResultsIn the phantom, the depth of thermal change in the 5- and 7-mm lumens averaged 6.3 and 6.0 mm along the basket, respectively, and in the 2- and 5-mm lumens, the depth of thermal change averaged 1.9 and 0.5 mm along the wire, respectively. In the swine, RF energy delivery led to angiographic occlusion at 12 of 13 sites. Thermal injury and occlusion were similar at the proximal, middle, and distal basket treatment zone, whereas injury and occlusion decreased from the proximal to the distal end of the 5-cm wire treatment zone. ConclusionsEndovascular delivery of RF energy via a conductive basket in medium-sized arteries or a guidewire in small arteries led to acute angiographic and histologic occlusion. The potential to induce stasis might be useful in settings where rapid occlusion is desirable.

Effectiveness of Hysteroscopic Morcellation of Endometrial Polyps Compared to Traditional Technique: A Comparison of Disease Recurrence

Study ObjectiveTo compare the outcomes between hysteroscopic morcellation of endometrial polyps and traditional techniques such as hysteroscopic resection with monopolar or bipolar radiofrequency energy, scissors and graspers or mechanical resection with polyp forceps.DesignRetrospective chart review.SettingAcademic tertiary referral center.Patients or Participants193 patients who underwent operative hysteroscopic polypectomy between January 2015 and May 2016.InterventionsHysteroscopic polypectomy with intrauterine morcellation, monopolar or bipolar radiofrequency energy, scissors and graspers or mechanical resection with polyp forceps with evaluation and/or treatment of recurrent abnormal uterine bleeding (AUB) after operative polypectomy.Measurements and Main ResultsThere were 9 patients who underwent hysteroscopic polypectomy with monopolar radiofrequency energy, 3 patients with bipolar radiofrequency energy, 91 patients with intrauterine morcellation, 67 patients with polyp forceps and 12 patients with scissors and graspers. The recurrence rate for AUB for monopolar was 1.89%, bipolar was 1.67%, intrauterine morcellation was 1.93%, polyp forceps was 1.84% and hysteroscopic scissors and/or graspers was 1.83%. Among the recurrences the average time until recurrence was 1162 days for monopolar, 207 days for bipolar, 749.5 days for intrauterine morcellation, 477.6 days for polyp forceps and 341.5 days for hysteroscopic scissors and graspers.ConclusionThere was no significant difference in terms of recurrence of AUB following the different modalities of operative hysteroscopy. Among the patients with recurrence in order of shortest time until recurrence: bipolar, hysteroscopic scissors and graspers, polyp forceps, intrauterine morcellation and monopolar.

Stray energy transfer in single-incision robotic surgery.

Stray energy transfer from surgical monopolar radiofrequency energy instruments can cause unintended thermal injuries during laparoscopic surgery. Single-incision laparoscopic surgery transfers more stray energy than traditional laparoscopic surgery. There is paucity of published data concerning stray energy during single-incision robotic surgery. The purpose of this study was to quantify stray energy transfer during traditional, multiport robotic surgery (TRS) compared to single-incision robotic surgery (SIRS). An in vivo porcine model was used to simulate a multiport or single-incision robotic cholecystectomy (DaVinci Si, Intuitive Surgical, Sunnyvale, CA). A 5s, open air activation of the monopolar scissors was done on 30W and 60W coag mode (ForceTriad, Covidien-Medtronic, Boulder, CO) and Swift Coag effect 3, max power 180W (VIO 300D, ERBE USA, Marietta, GA). Temperature of the tissue (°C) adjacent to the tip of the assistant grasper or the camera was measured with a thermal camera (E95, FLIR Systems, Wilsonville, OR) to quantify stray energy transfer. Stray energy transfer was greater in the SIRS setup compared to TRS setup at the assistant grasper (11.6 ± 3.3°C vs. 8.4 ± 1.6°C, p = 0.013). Reducing power from 60 to 30W significantly reduced stray energy transfer in SIRS (15.3 ± 3.4°C vs. 11.6 ± 3.3°C, p = 0.023), but not significantly for TRS (9.4 ± 2.5°C vs. 8.4 ± 1.6°C, p = 0.278). The use of a constant voltage regulating generator also minimized stray energy transfer for both SIRS (0.7 ± 0.4°C, p < 0.001) and TRS (0.7 ± 0.4°C, p < 0.001). More stray energy transfer occurs during single-incision robotic surgery than multiport robotic surgery. Utilizing a constant voltage regulating generator minimized stray energy transfer for both setups. These data can be used to guide robotic surgeons in their use of safe, surgical energy.

Monopolar stray energy in robotic surgery.

Stray energy transfer from monopolar radiofrequency energy during laparoscopy can be potentially catastrophic. Robotic surgery is increasing in popularity; however, the risk of stray energy transfer during robotic surgery is unknown. The purpose of this study was to (1) quantify stray energy transfer using robotic instrumentation, (2) determine strategies to minimize the transfer of energy, and (3) compare robotic stray energy transfer to laparoscopy. In a laparoscopic trainer, a monopolar instrument (L-hook) was activated with DaVinci Si (Intuitive, Sunnyvale, CA) robotic instruments. A camera and assistant grasper were inserted to mimic a minimally invasive cholecystectomy. During activation of the L-hook, the non-electric tips of the camera and grasper were placed adjacent to simulated tissue (saline-soaked sponge). The primary outcome was change in temperature from baseline (°C) measured nearest the tip of the non-electric instrument. Simulated tissue nearest the robotic grasper increased an average of 18.3 ± 5.8°C; p < 0.001 from baseline. Tissue nearest the robotic camera tip increased (9.0 ± 2.1°C; p < 0.001). Decreasing the power from 30 to 15W (18.3 ± 5.8 vs. 2.6 ± 2.7°C, p < 0.001) or using low-voltage cut mode (18.3 ± 5.8 vs. 3.1 ± 2.1°C, p < 0.001) reduced stray energy transfer to the robotic grasper. Desiccating tissue, in contrast to open air activation, also significantly reduced stray energy transfer for the grasper (18.3 ± 5.8 vs. 0.15 ± 0.21°C, p < 0.001) and camera (9.0 ± 2.1 vs. 0.24 ± 0.34°C, p < 0.001). Stray energy transfer occurs during robotic surgery. The assistant grasper carries the highest risk for thermal injury. Similar to laparoscopy, stray energy transfer can be reduced by lowering the power setting, utilizing a low-voltage cut mode instead of coagulation mode and avoiding open air activation. These practical findings can aid surgeons performing robotic surgery to reduce injuries from stray energy.

P3799Experimental model of interatrial block by Bachmann bundle conduction block

Abstract Background The recognition of advanced IAB is becoming an important clinical landmark due to its association with atrial fibrillation, the so-called Bayes' syndrome. The electrocardiographic (ECG) criteria of interatrial block (IAB) have been established. A P-wave duration ≥120 ms is considered partial IAB and if there is a biphasic P-wave in the inferior leads advanced IAB. The pathophysiology of this ECG finding has been largely discussed. IAB has been explained as the result of the retrograde activation of left atrium due to complete block in the Bachmann bundle (BB). Purpose To assess the ECG changes resulting of blocking BB conduction in an experimental healthy animal model. Additionally, to compare the pattern of activation of the left atrium before and after the block. Methods Six open-chest anesthetized healthy adult swine were studied. A twelve-lead ECG was continuously recorded. The BB was epicardially accessed at the traversus sinus of the pericardium. At that level, monopolar electrosurgical energy (3 animals) and radiofrequency energy (3 animals) (Boston Scientific Blazer™ II XP, 8 mm tip) was applied until extensive tissue disruption was present and permanent P-wave changes observed. An electroanatomical map CARTO® XP (Biosense Webster Inc) of the right and left atrium was performed in two animals before and after energy deployment. Finally, animals were sacrificed, and tissue samples collected for anatomopathological examination. Results After energy application, all animals showed a significant prolongation of P-wave duration from 59±11 msec to 115±13 msec (p&lt;0.001) with appearance of a biphasic P-wave pattern in the inferior leads. The CARTO® maps showed a change in left atrial activation, cranio-caudal at baseline and caudo-cranial at the end of the procedure. (Figure) The histological analysis showed transmural lesions at the level of the BB in all the specimens. ECG/CARTO maps: Baseline and after block Conclusion IAB ECG pattern, accompanied by a marked change in the activation of the left atrium, develops after blocking the conduction at the level of the BB in an experimental healthy animal model. These results confirm the association of IAB and BB conduction block and suggest that IAB represents an independent entity. Acknowledgement/Funding Fundaciό Privada Daniel Bravo Andreu

Pulsed radiofrequency energy device (PEAK plasmablade™) and CustomBone® Cranioplasty: an appealing surgical rendez-vous

Background CustomBone® prosthesis is a widely recognized effective and successful technique for the reconstruction of cranial bone defects. Prior the cranioplasty implant, meticulous dissection within thick scar tissue is required. During this delicate surgical manoeuvre is vital to avoid damage to the skin flap itself and to the underlying cerebrovascular structures. We report our experience and potential applications of a novel, pulsed monopolar radiofrequency energy device (PEAK PlasmaBlade™, Medtronic plc). It reduced the incidence of post operativesubgaleal hematoma, the operative times and the intra operative blood loss following cranioplasty compared to the traditional scalpel and scissor dissection. Methods The authors present a one centre case series study to review the indications, safety and efficacy of the PEAK PlasmaBlade™ in adult patientsunderwent cranioplasty. Two surgical techniques for tissue dissection were compared: PEAK PlasmaBlade™ versus scalpel and scissor dissection (SSD). Treatment outcomes following each of these surgical approaches, relative to rate of post-operative subgalealhematoma formation, hospital admission, and operative times were compared. Results A total of 10 patients that had cranioplasty treatment were evaluated. In patients underwent scalp dissection with the PEAKPlasmaBlade™, we observed a reduction in the operative times, in the subgaleal hematoma formation and then in the hospital stay. Conclusion PEAK PlasmaBlade™ revealed to be a safe and effective device in tissues dissection for cranioplasty implant. It provided reduction of the rate of subgaleal hematoma formation, operating times and less potential risk to damage cerebrovascular structures.

Gait and electromyographic alterations due to early onset of injury and eventual rupture of the cranial cruciate ligament in dogs: A pilot study.

Identify relevant electromyography (EMG), kinematic, and kinetic changes resulting from monopolar radiofrequency energy (MRFE)-induced cranial cruciate ligament (CCL) injury and eventual rupture in dogs. Experimental, repeated measures. Five purpose-bred female dogs free of orthopedic and neurologic disease. Surface EMG, joint kinematics, and ground reaction forces were assessed at a trot in the pelvic limbs at baseline, at 2 and 4 weeks after unilateral MRFE-induced CCL injury, and at 4, 8, and 16 weeks after CCL rupture (CCLR). After MRFE-induced injury, average hip joint range of motion (ROM) during stance decreased within the untreated pelvic limb. After CCLR, stifle flexion angles decreased within the treated limb at 8 weeks and within the untreated pelvic limb at all time points, whereas average tarsal joint ROM decreased in the treated limb and increased in the untreated limb. Peak vertical ground reaction force and impulse decreased within the treated limb. Qualitative alterations of many EMG values were noted after MRFE-induced injury and CCLR, although significant differences between limbs or from baseline values were not detected. Monopolar radiofrequency energy-induced injury altered contralateral hip kinematics, suggesting early regional compensatory gait alterations. After CCLR, additional compensatory gait patterns occurred in both pelvic limbs. The qualitative analysis of trial-averaged EMG data in this small population supports a relationship between neuromuscular function and induced CCL injury leading to rupture.

Use of Pulsed Radiofrequency Energy Device (PEAK Plasmablade) in Neuromodulation Implant Revisions.

Battery replacement or revision surgery for neuromodulation implants is conventionally performed using sharp dissection. Meticulous dissection within thick scar tissue is vital to avoid damage to surrounding lead(s), which could result in more extensive revision surgery. Traditional electrosurgery devices are contraindicated as the emitted energy can be transferred to the hardware, resulting in implant or tissue damage with severe consequent complications. We report our experience and potential applications of a novel, pulsed monopolar radiofrequency energy device (PEAK PlasmaBlade, Medtronic PLC, Minneapolis, Minnesota, USA), which facilitates dissection around implants without the risk of damaging or transmitting energy through the system. We conducted a 2-center retrospective study to review the indications, safety, and efficacy of the PlasmaBlade in 57 cases requiring either neuromodulation system replacement or revision. Deep brain stimulator (DBS) battery replacements were undertaken in 45 cases, 8 vagal nerve stimulator battery revisions, 2 intrathecal baclofen system revision, 1 DBS extension revision, and 1 DBS scar revision around the cranial portion of the lead. All cases proceeded without adverse event or damage to lead/generator and with a subjective and objective impression of significant time savings. Average operating times for battery replacements were reduced from 37 to 26 minutes (P= 0.015). In our experience, the PlasmaBlade is safe to use in revising/replacing neuromodulation implants. We observed no damage or transmission of energy to the implants or leads; additional advantages of the system include reduced operating times, less damage to surrounding tissue, and the potential to facilitate revision procedures in awake patients under local anesthesia.

Efficacy of monopolar radiofrequency in middle and lower face laxity

Aim: In recent years, radiofrequency (RF) systems have become one of the most commonly used rejuvenation methods, especially in the skin of the mid-lower face. In this study, the efficacy of monopolar RF energy in mid-lower face skin sagging was evaluated.

Effects on the Distal Radioulnar Joint of Ablation of Triangular Fibrocartilage Complex Tears With Radiofrequency Energy

This cadaver study investigated the temperature profile in the wrist joint and distal radioulnar joint (DRUJ) during radiofrequency energy (RFE) application for triangular fibrocartilage complex resection. An arthroscopic partial resection of the triangular fibrocartilage complex using monopolar and bipolar RFE was simulated in 14 cadaver limbs. The temperature was recorded simultaneously in the DRUJ and at 6 other anatomic locations of the wrist during RFE application. The mean temperature in the DRUJ was 43.3 ± 8.2°C for the bipolar system in the ablation mode (60 W) and 30.4 ± 3.4°C for the monopolar system in the cut mode (20 W) after 30 seconds. The highest measured temperature in the DRUJ was 54.3°C for the bipolar system and 68.1°C for the monopolar system. The application of RFE for debridement or resection of the triangular fibrocartilage complex in a clinical setting can induce peak temperatures that might cause damage to the cartilage of the DRUJ. Bipolar systems produce higher mean temperatures than monopolar devices. RFE application increases the mean temperature in the DRUJ after 30 seconds to a level that may jeopardize cartilage tissue.

Treatment of stand-alone atrial fibrillation with a right thoracoscopic approach employing a microwave or monopolar radiofrequency energy source: long-term results.

Minimally invasive surgery for atrial fibrillation (AF) has rapidly evolved recently. The long-term efficacy of most of these procedures is poorly known. Between 2006 and 2010, 38 drug-resistant, symptomatic patients with stand-alone AF underwent unilateral, thoracoscopic, off-pump ablation. The mean age was 60 ± 8.2 (range 42-75) years and the mean AF duration was 46 ± 62 (range 3-240) months. Sixteen patients (42%) had paroxysmal, 9 (24%) had persistent and 13 (34%) had long-standing persistent AF. A box lesion was created using a microwave (26 patients) or monopolar radiofrequency (12 patients) system. Patients were prospectively followed with repeat electrocardiograms (ECGs) and ECG Holters. Additional catheter ablation was offered to patients with recurrence of arrhythmia. All procedures were completed as planned with one conversion to sternotomy, zero mortality and minimal in-hospital complications. The mean follow-up duration was 70 ± 19 (range 20-88) months. Arrhythmia-free survival rates after the procedure were 50, 44.4, 24.1 and 10.8% at 6, 12, 36 and 60 months, respectively, with most recurrences in the first 6 months. Twelve patients underwent additional catheter ablation(s); from the last intervention, 75% of them were in sinus rhythm (SR) with a mean follow-up of 31 ± 23 (range 4-86) months. Overall, at the end of follow-up, only 3 patients were still in SR without any arrhythmia recurrence. Major complications (cerebral, peripheral embolism or bleeding) occurred in 5 patients. Unilateral, thoracoscopic AF ablation is safe and technically feasible. However, the results of the microwave and monopolar radiofrequency devices were less than satisfactory, with a gradual decline in arrhythmia-free survival over a very long-term follow-up.

Antenna Coupling Explains Unintended Thermal Injury Caused by Common Operating Room Monitoring Devices

Unintended thermal injury from patient monitoring devices (eg, electrocardiogram pads, neuromonitoring leads) results in third-degree burns. A mechanism for these injuries is not clear. The monopolar "bovie" emits radiofrequency energy that transfers to nearby, nonelectrically active cables or wires without direct contact by capacitive and antenna coupling. The purpose of this study was to determine if, and to what extent, radiofrequency energy couples to common patient monitoring devices. In an ex vivo porcine model, monopolar radiofrequency energy was delivered to a handheld "bovie" pencil. Nonelectrically active neuromonitoring and cardiac-monitoring leads were placed in proximity to the monopolar pencil and its cord. Temperature changes of tissue touched by the monitoring lead were measured using a thermal camera immediately after a 5-second activation. The energy-device cords were then separated by 15 cm, the power was reduced from 30 W coag to 15 W coag and different cord angulation was tested. An advanced bipolar device, a plasma-based device, and an ultrasonic device were also tested at standard settings. The neuromonitoring lead increased tissue temperature at the insertion site by 39 ± 13°C (P<0.001) creating visible char at the skin. The electrocardiogram lead raised tissue temperature by 1.3 ± 0.5°C (P<0.001). Decreasing generator power from 30 W to 15 W and separating the bovie cord from the neuromonitoring cord by 15 cm significantly reduced the temperature change (39 ± 13°C vs. 26±5°C; P<0.001 and 39 ± 13°C vs. 10 ± 5°C; P<0.001, respectively). Lastly, monopolar energy increased tissue temperatures significantly more than argon beam energy (34 ± 15°C), advanced bipolar energy (0.2 ± 0.4°C), and ultrasonic energy (0 ± 0.3°C) (all P<0.001). Stray energy couples to commonly used patient monitoring devices resulting in potentially significant thermal injury. The handheld bovie cord transfers energy via antenna coupling to neuromonitoring leads that can raise tissue temperatures over 100°F (39°C) using standard settings. The most effective ways to decrease this energy coupling is to reduce generator power, increase the separation between wires, or utilize lower voltage energy devices such as ultrasonic or bipolar energy.

RFE based chondroplasty in wrist arthroscopy indicates high risk for chrondocytes especially for the bipolar application

BackgroundThe application of radiofrequency energy (RFE) has become widespread for surgical performed chondroplasty especially due to the anticipated sealing effect, however the safety of this procedure in the wrist remains unclear. The purpose of this study was to investigate the subchondral temperature during radiofrequency energy (RFE) application simulating chondroplasty in an arthroscopic setting of the wrist.MethodsA chondroplasty of the lunate fossa was performed during an arthroscopy setting on 14 cadaver arms using monopolar or biopolar RFE. The temperature was recorded simultaneously from 7 predefined anatomical landmarks.ResultsThe mean temperature for both application modes did not exceed more than 30°C at all measured points, except for the lunate fossa. The highest subchondral measured peak temperature was 49.35°C (monopolar) and 69.21°C (bipolar) in the lunate fossa. In addition, the temperature decreased for both radiofrequency (RF) devices depending on the distance of the sensors to the RF-probe.ConclusionIt remains to be questionable how safe RFE can be used for chondroplasty in wrist arthroscopy under continuous irrigation and constant movement to obtain the desired sealing effect. However, the bipolar device should be applied with more caution since peak temperature in the lunate fossa almost reached 70°C even under continuous irrigation.

Temperature in and Around the Scapholunate Ligament During Radiofrequency Shrinkage: A Cadaver Study

To investigate whether applied radiofrequency energy (RFE) for shrinkage of the scapholunate interosseus ligament reaches temperatures required for ligament shrinkage while leaving adjacent structures unaffected. Standard wrist arthroscopy was performed on 7 pairs of cadaveric limbs with continuous saline irrigation and gravity-assisted outflow through an 18-gauge needle. We subjected 14 scapholunate ligaments to treatment with monopolar (n= 7) or bipolar (n= 7) RFE for ligament shrinkage. Temperature was recorded simultaneously inside the dorsal part of the scapholunate interosseus ligament at a depth of 0.9 ± 0.1 mm and at 6 other sites in and around the wrist because thermal shrinkage starts at 60°C to 65°C. We observed an increase in temperature corresponding to the time of energy application. The highest measured peak temperatures at the scapholunate ligament were 43°C (monopolar) and 32°C (bipolar). Mean temperatures at 30 seconds of application were 29°C ± 7°C (monopolar) and 28°C ± 3°C (bipolar). Temperatures sufficiently high to induce ligament shrinkage were not reached with either monopolar or bipolar RFE. We did not monitor temperature levels responsible for damage on adjacent cartilage or immediately adjacent capsular tissue in this setting. This study suggests that RFE for capsular shrinkage in the wrist is safe but ineffective.

Clinical application of a high frequency electric knife with coblation technology for temporomandibular joint arthroscopic surgery

ArthroCare Multi-electrode SystemTM with Coblation technology (bipolar) and Vulcan Electro Thermal Arthroscopy SystemTM (monopolar) has been used in the fields of neurosurgery and orthopaedic surgery. Coblation, derived from cooler, controlled ablation, is a patented process employing bipolar radiofrequency technology to achieve precise and rapid tissue removal with minimal thermal damage to collateral tissue. Radiofrequency power setting and heat loss through lavage solution play a significant role in heat distribution and morphologic alterations in joint capsule after arthroscopic application of monopolar radiofrequency energy. This study examined the efficacy and safety of these instruments to temporomandibular joint arthroscopic surgery.

Clinical application of a high frequency electric knife with coblation technology for temporomandibular joint arthroscopic surgery

Purpose: ArthroCare Multi-electrode System™ with Coblation technology ibipolar j and Vulcan Electro Thermal Arthroscopy System™ (monopolar) have been used in the fields of neurosurgery and orthopaedic surgery. Coblation, derived from cooler, controlled ablation, is a patented process employing bipolar radiofrequency technology to achieve precise and rapid tissue removal with minimal thermal damage to collateral tissue. Radiofrequency power setting and heat loss through lavage solution play a significant role in heat distribution and morphologic alterations in joint capsule after arthroscopic application of monopolar radiofrequency energy.

Temperature Profile of Radiofrequency Probe Application in Wrist Arthroscopy: Monopolar Versus Bipolar

The purpose of this study was to investigate the changes in temperature during wrist arthroscopy comparing monopolar and bipolar radiofrequency energy (RFE). A standard wrist arthroscopy was performed on 14 arms of 7 cadavers without irrigation or with continuous irrigation with 0.9% saline solution and gravity-assisted outflow through an 18-gauge needle. We treated 7 wrists with a bipolar device (VAPR II with 2.3-mm side effect electrodes; DePuy Mitek, Westwood, MA) and 7 wrists with a monopolar device (OPES Ablator for small joints, 45°; Arthrex, Naples, FL). The temperature was recorded simultaneously from 7 predefined anatomic landmarks. We observed an increase in the temperature corresponding to the time of energy application. The highest measured peak temperatures were 52°C (monopolar) and 49.5°C (bipolar) without irrigation. Continuous irrigation led to a significant reduction in the temperature at the site of the energy application. The mean temperature decreased by 7°C for the monopolar system and 5°C for the bipolar system when irrigation was used. For both radiofrequency devices, we found a decrease in the temperature proportional to the distance of the sensors to the radiofrequency probe. Monopolar and bipolar RFE can be safely used in wrist arthroscopy if a continuous irrigation system is applied and the energy impulse does not exceed 5 to 10seconds. However, it should be used with great care to avoid local heat damage especially at the cartilage. This basic science study was performed to gain data concerning the temperature in wrist arthroscopy and to broaden the knowledge about the risks when using RFE. Furthermore, we sought to control side effects of RFE by finding the best applied form of RFE regarding duration and pulsation (monopolar/bipolar).

Radiofrequency energy antenna coupling to common laparoscopic instruments: practical implications

Electromagnetic coupling can occur between the monopolar "Bovie" instrument and other laparoscopic instruments without direct contact by a phenomenon termed antenna coupling. The purpose of this study was to determine if, and to what extent, radiofrequency energy couples to other common laparoscopic instruments and to describe practical steps that can minimize the magnitude of antenna coupling. In a laparoscopic simulator, monopolar radiofrequency energy was delivered to an L-hook. The tips of standard, nonelectrical laparoscopic instruments (either an unlit 10 mm telescope or a 5 mm grasper) were placed adjacent to bovine liver tissue and were never in contact with the active electrode. Thermal imaging quantified the change in tissue temperature nearest the tip of the telescope or grasper at the end of a 5 s activation of the active electrode. A 5 s activation (30 watts, coagulation mode, 4 cm separation between instruments) increased tissue temperature compared with baseline adjacent to the grasper tip (2.2 ± 2.2 °C; p = 0.013) and telescope tip (38.2 ± 8.0 °C; p < 0.001). The laparoscopic telescope tip increased tissue temperature more than the laparoscopic grasper tip (p < 0.001). Lowering the generator power from 30 to 15 Watts decreased the heat generated at the telescope tip (38.2 ± 8.0 vs. 13.5 ± 7.5 °C; p < 0.001). Complete separation of the camera/light cords and the active electrode cord decreased the heat generated near the telescope tip compared with parallel bundling of the cords (38.2 ± 8.0 vs. 15.7 ± 11.6 °C; p < 0.001). Commonly used laparoscopic instruments couple monopolar radiofrequency energy without direct contact with the active electrode, a phenomenon that results in heat transfer from a nonelectrically active instrument tip to adjacent tissue. Practical steps to minimize heat transfer resulting from antenna coupling include reducing the monopolar generator power setting and avoiding of parallel bundling of the telescope and active electrode cords.

The increasing use of nonablative radiofrequency in the rejuvenation of the skin

Evaluation of: Elsaie ML, Choudhary S, Leiva A, Nouri K. Nonablative radiofrequency for skin rejuvenation. Dermatol. Surg. 36, 577–589 (2010).The field of body contouring and tissue tightening has grown very rapidly over the past several years, with many new devices appearing on the market that utilize radiofrequency (RF) energy to effectively tighten and rejuvenate the skin. What originally began with a single monopolar RF device has progressed into a world in which there are skin-tightening devices that utilize, besides monopolar RF energy, bipolar energy and tripolar energy, and newer machines that boast five and eight poles of RF energy. Each of these devices claims to have positive effects on the skin, which can lead to tissue tightening and ultimate rejuvenation of the skin.