Common uses and cited complications of energy in surgery.

The review includes a thorough search of literature concerning the physics, applications, success, complications and comparison of various energy sources in surgery. Priority was given to human studies and laparoscopic procedures. However, the studies involving animals (both in vivo and in vitro) and open procedures which were unique and relevant to the assessment of the energy sources were considered. Emphasis was placed on more recent studies covering the latest techniques and studies conducted on live patients in the United States. The keywords used in the search were numerous and the websites such as Medline, PubMed, SpringerLink and Google were extensively covered along with various books published in the field. Electrosurgery was developed by Dr. William T. Bovie in the 1920s, where a spark gap generator was used to build the first electrosurgery tool, commonly known as RF knife or ‘Bovie’ [ 3 ]. In the 1950’s, the first bipolar unit was built by Dr. Leonard Malis, wherein two electrodes were used for gripping and manipulating the tissue. In electrosurgery, heat is generated in the tissue by the flow of radio frequency (RF) electric current unlike electrocautery where the heat is transferred directly from the tool to the tissue. The use of RF current (voltage in the range of 300 to 500 KHz) eliminates neuromuscular stimulation, which ceases above 100 KHz. When the RF electrical energy is made to concentrate in a very small area in the tissue, typically by applying the energy through pointed or hooked tool tips, the resulting high concentration of current flow in a narrow area increases the cellular temperature which leads to various effects on the tissue including, coagulation, dessication or dehydration and carbonization. The RF energy can be applied to tissue by using either monopolar or bipolar tools. In monopolar electrosurgery, the electrical circuit is completed by the passage of current from the active electrode at the surgical site to the dispersive electrode (or the return electrode) attached to the body of the patient. The active electrode can be of any form (usually a point, hook or a blade) with sharp edges and/or blunt edges. The sharp edges increase the current density (the amount of current per unit area) and used for cutting whereas the blunt edges are used for coagulation. The return electrode is usually a wide pad, attached to the skin of the patient, which disperses the heat and safely leads the current out of the body. In bipolar electrosurgery both active and return electrodes are located in the same tool and the electrical circuit is closed by the small area of tissues that are grasped or manipulated by the tool. Bipolar tools are, thus, usually designed as grippers or forceps. Since the current only has to travel short distances in bipolar surgery, the voltage required for the surgery is low. Lower voltage is better for uniform drying of the tissue which minimizes the chance of re-bleeding. Thus the bipolar devices are more suitable for coagulation rather than cutting. The RF energy is applied through specialized electrosurgical generators, which are RF wave form generators with different duty cycles (percentage of time the energy is applied). Different tissue effects such as cutting, coagulation can be achieved by selecting different duty cycles with 100 % duty cycle enables cutting whereas lower duty cycles can be effectively used for coagulation. Though electrosurgical generators produced by each manufacturer are different, they usually provide selections such as pure cutting, coagulation and blended waveforms. The waveforms with different duty cycles can be used to produce four main effects in electrosurgery namely, cutting, coagulation, desiccation and fulguration. The cutting is achieved by using a continuous waveform (100 % duty cycle) applied through the active electrode of a monopolar electrosurgical tool with a pointed tip. The narrow tip allows for large current concentration and when placed near the tissue but not in contact, generates an arc through which the current rushes to the tissue generating large amount of heat (greater than 100°C) which leads to rapid tissue vaporization and induces cutting. When a blunt instrument tip is used with contact on the tissue, the decreased current concentration due to increased surface area leads to increase in the tissue temperature but not to point of vaporization and creates a coagulum at temperature between 70 to 80°C and desiccation at temperature of 90°C. To perform coagulation or desiccation, a lower duty cycle high voltage waveform is used but can also be performed with 100 % duty cycle lower voltage cutting waveform as well. Finally in fulguration, a lower duty cycle high voltage waveform is applied through the active electrode of a pointed monopolar electrosurgical tool tip in non contact mode close to the tissue. With high voltage and low duty cycle (usually 6 %), the heat generated by the current flowing through the arc from the tool tip heats the tissues to form coagulum and with repeated application, increases the temperate to 200°C or more forming carbonization or fulguration. The most commonly used electrosurgery devices are listed in Table 1 . The bipolar instruments provide compression force in addition to thermal energy, which helps in better sealing of blood vessels and attaining better burst pressures. Thus these instruments seal larger blood vessels as opposed to monopolar devices which are limited to smaller vessels - usually less than 2mm [ 4 ]. The earlier generation of electrosurgical tools did not have temperature control and hence, resulted in thermal injuries. The latest instruments (e.g., Ethicon EndoSurgery’s ENSEAL) claim to measure temperature or impedance to provide consistent heating to prevent injuries. Electrosurgery accounts for 80 % of all cutting and coagulation in surgeries performed today. According to the Association of periOpertaive Registered Nurses (AORN), there are around 40,000 patient burn cases annually due to faulty electrosurgical devices and in 1999 alone, nearly $600 million was paid in claims for those injuries [ 5 ]. Care should be taken when operating the electrosurgical devices, particularly monopolar devices. The sparking effect at the tool tip may cause an explosion when it comes into contact with inflammable gases that are often used for anesthesia during the operation. Further, the current travelling through the body can interfere with any implanted medical devices such as pacemakers [ 6 ] and defibrillators. A metal instrument or implant that comes in the way of the current passing through the body may create a different loop causing tissue damage in unwanted regions. Other mechanisms through which injuries can occur during electrosurgery include insulation failure [ 7 ], direct and capacitive coupling. Insulation of the electrosurgical tool may break due to repetitive use of the equipment, high intensity of current flowing through the wire and in repeated sterilization process. Burns occur at places of insulation defect and can be fatal especially when the defect is small which leads to high current concentration. Moreover the insulation defect is often very small and will be difficult to detect using the naked eye and an active electrode monitoring system may abate injury [ 8 ]. Direct coupling occurs when the active electrode is either intentionally or inadvertently touched by another tool or scope, in which case, energy can be transmitted through the other tool to the tissues. Though in many instances, it is used intentionally, in laparoscopic procedures, it is often dangerous since the view of surrounding organs is limited. Capacitive coupling may occur in a laparoscopic surgery when the tools, tissues and trocars are in close proximity creating capacitance effect (build up of charge between two conductors separated by an insulator). This stored charge may discharge causing unintended tissue damage in the immediate vicinity. If possible, the use of metal and hybrid (with plastic) cannula should be avoided to eliminate injuries. This may be a particular hazard in the emerging technique of single port laparoscopic surgery where all of the instruments are in close proximity. Though the spread of current through the body is eliminated by the use of bipolar electrosurgery, chance of damage to adjacent tissues still exists [ 9 ]. Apart from the common laparoscopic complications that arise due to surgical error, the other major complication from electrosurgery is the thermal injuries to adjacent organs. However, the complications can be both intra-operative and postoperative and are specific to the type of procedure performed. Complicating the matter further is that the maximum temperature and thermal spread when using energy based devices varies based on the types of target tissue and the type of energy sources used [ 10 ]. Monopolar electrosurgery was shown to have higher temperature and thermal spread [ 11 – 13 ]. Various studies on laparoscopic procedures have shown complications while using monopolar and bipolar electrosurgical instruments that includes conversions, failures, and recurrences [ 14 – 19 ]. There are cases in which death has been reported when using monopolar electrosurgical device [ 20 , 21 ]. Specifically Agarwal et al. [ 22 ] mentioned that the use of an energy source, especially monopolar electrosurgery is the culprit for many of the injuries during laparoscopic cholecystectomy. Electrosurgery has the highest number of thermal injuries, but it still is one of the most popular techniques used in laparoscopy. Out of the two electrosurgical modalities, monopolar electrosurgery causes the most thermal damage but bipolar devices have also shown to produce thermal damage [ 11 ]. Studies have shown that the bipolar device has the least amount of thermal spread among the various energy devices [ 11 , 12 , 23 ] and provides safe sealing and cutting quality that are similar to other energy based devices [ 20 ]. Bipolar electrosurgery devices have shown to have shorter dissection time, provided better seal quality, lesser blood loss, fewer conversion rates and are more cost effective than monopolar electrosurgery [ 24 – 26 ]. In laparoscopic cholecystectomy (LC), a common laparoscopic procedure which involves the use of energy, bipolar modality is shown in one study to have performed better than monopolar electrosurgery [ 27 ]. In a number of other studies comparing different energy devices, the bipolar electrosurgery devices have performed better than devices using other forms of energy sources [ 26 , 28 – 30 ]. High success rate have also been reported in surgical outcome reports using bipolar energy devices [ 14 , 15 , 18 ]. Hence the cost of bipolar electrosurgery devices may be justified for complex surgical cases. Monopolar technique might be preferable for simpler surgical procedures when adequate care is taken while operating in the vicinity of critical organs. For example, making incisions on the skin before inserting the laparoscopic instruments is a job for the monopolar tool. The risk from electrosurgery can further be reduced by limiting the thermal damage during electrosurgery. For example, Dodde et al. [ 31 ] reported a novel thermal management system to reduce the thermal spread during monopolar electrosurgery. One common safety measure is the optimization of the voltage application time. Most of the electrosurgical units come with various power settings for cutting and coagulation. The right setting should be chosen for the specific procedure. Tissue damage is further reduced by the introduction of a hydrating medium to keep the surgical area wet and moist. As long as the above mentioned precautions are taken and the common risk factors are considered, electrosurgery maybe used with confidence. The use of ultrasonic energy in medicine has been reported as early as 1960, where it was used to treat Meniers’s disease. It has been used in the cutting and coagulation of tissue in the late 1980s [ 33 ] where Amaral [ 34 ] popularized the technique and used it successfully in over 200 patients undergoing laparoscopic cholecystectomy. The basic working principle of ultrasonic surgical instruments such as ultrasonically activated scalpel (UAS) is to use the low frequency mechanical vibrations (ultrasonic energy in the range of 20–60 kHz) of the tool tips or the blades for tissue cutting and coagulation [ 32 ]. The mechanical vibrations when transferred to the tissues on contact induces protein denaturation by breaking down the hydrogen bonds in tissues due to the internal cellular friction caused by the vibrations [ 33 ]. The mechanical vibrations are produced by the piezoelectric transducers embedded in the tools which convert the applied electrical energy to mechanical vibrations which are then transferred to the active blades for cutting or coagulation. The HS operate at a frequency of 55.5 kHz whereas devices operating at various other frequencies also exist [ 35 ]. The cutting using an Ultrasonic surgical instrument is achieved by two methods. For tissues and muscles with high protein densities, the mechanical stretching of the tissues beyond its elastic limit due to the longitudinal motion of the sharp blades between 60 to 100 μm at 55.5 kHz is used for cutting. For tissues with low protein densities, such as liver, cavitation effect in which intercellular water is vaporized at lower temperatures due to mechanical vibrations, there by rupturing the cells is used for cutting. In general the cutting and coagulation in UAS depends on various factors such as grip pressure, the shape and area of the blades in contact with the tissues and the power settings [ 34 ]. The major advantage of using UAS is that it produces less heat compared to other energy devices (less than 80° C compared to 100° C for electrosurgery) thereby reducing the risk of thermal injury [ 35 ]. Due to lesser heat generation, charring and desiccation is also greatly reduced. Since no smoke is produced, except for the mist produced due to cavitation effect which dissipates much faster, UAS offers unobstructed view for endoscopic/ laparoscopic procedures. The UAS does not transmit active current in the tissues and thereby eliminate any risk of electric shock. The most commonly used ultrasonic energy devices are listed in Table 1 . Not many complications were reported in the use of harmonic scalpel in laparoscopy. General disadvantages of ultrasonic devices include slower coagulation compared to electrosurgery, altering of the frequency or impedance of the surgical system itself due to blade fatigue, temperature elevation, excessive applied pressure, or improper use. Ultrasonic energy causes atomization of fluid, which may create a transient mist. However, overall dissection time may be shorter with ultrasonic cavitation aspirators (UCA) or ultrasonic-activated scalpels after the initial learning curve [ 36 ]. It has been shown in many studies that the ultrasonic devices are not as efficient in sealing medium to large sized blood vessels [ 26 , 37 , 38 ]. It is also shown that UAS produces higher average temperatures [ 10 ] and is not reliable in sealing vessels larger than 3mm [ 39 ]. In [ 40 ] it was shown that though there is no visible injury to naked eye during dissection experiments on a swine using a UAS, histological examination had revealed serious injuries to various structures. Complications reported in the use of ultrasonic energy in laparoscopic surgery includes injury to sigmoid colon [ 41 ], postoperative bleeding [ 42 ] and an ischemic lesion [ 28 ]. Even the overheating of tissue (the non active blade of a UAS) after a continuous activation of more than 10s resulted in histological damage to the intestinal mucosa in a porcine [ 43 ]. The general conclusion of most studies advocating the use of ultrasonic energy is that the minimal thermal spread leads to minimal thermal injury. However, there are studies that contradict the statement by measuring the temperature of the tool tip instead of thermal spread in the tissue. In [ 44 ] it was shown that at higher power settings, the ultrasonic devices (Ultracision and Autosonix) created large thermal spread (up to 25.7 mm) and high temperatures (140ºC at 10 mm distance) in porcine organs. In another study, the harmonic ACE [ 10 ] is shown to have taken twice as long to cool down when compared to the other devices and the temperatures generated by the ACE were inversely proportional to the thickness of the tissue. Kinoshita et al. [ 48 ] says that the temperatures (150ºC) and thermal spread (10mm) caused by ultrasonic device is far less than those caused by electrosurgery (350ºC and 22mm respectively) in the porcine blood vessel cutting and coagulation. There are various reports of successful laparoscopic procedures using ultrasonic energy devices. This includes gynecological [ 45 – 48 ], laparoscopic cholecystectomy [ 49 – 51 ], laparoscopic appendectomy [ 52 ], laparoscopic myomectomy [ 53 , 54 ], laparoscopic colorectal [ 55 ], laparoscopic salpingo-oophorectomy [ 56 ] and laparoscopic management of cornual heterotopic pregnancy [ 57 ]. Ultrasonic scalpel (Harmonic ACE) was also successfully used in division of pulmonary vessels in video assisted lung resection [ 58 ]. Though proven to be an effective tool in gynecological procedures, it is not a good tool for delicate reconstructive surgery for fertility due to the cavitational effect [ 47 ]. Janssen et al. [ 51 ] showed that in laparoscopic cholecystectomy, the learning curve of the surgeons using HS was very short compared to electrosurgery. The general conclusion that can be drawn from the observations is that ultrasonic energy has more advantages than disadvantages. Given the fact that more recent literature is available in the field than other energy methods and the increasing market share of ultrasonic medical devices [ 59 ], it can be said that ultrasonic energy may have an increasing role in the field of surgery. The first use of lasers in laparoscopic surgery was recorded in 1979 [ 60 ] and the regular use of laparoscopic laser surgery has been reported as early as 1982 [ 61 ]. In a very short span of time, lasers became very widespread in the medical field - ranging from cosmetic treatments to highly complicated surgeries such as atrial fibrillation (AF) treatment [ 62 , 63 ]. Today, lasers are relegated mostly to gynecological procedures. Lasers generate heat by applying a concentrated beam of light. In a laser system, electromagnetic or light waves are amplified multiple fold in an optical resonator (which contains mirrors and a gain medium) and passed out in the form of high intensity light waves. The amount of amplification in the resonator determines the amount of energy transmitted by the light waves which are then absorbed by the tissue. This energy absorbed by the tissue then manifests itself into heat which cuts and coagulates the tissue. The frequency of the laser beam determines the width of the laser beam that can be generated (the higher the frequency of the wave, the lower the diameter of the beam) and most commercial lasers use infra-red to ultraviolet frequencies for medical applications. The power or intensity of a laser is measured in terms of ‘irradiation’ defined as the ratio of power applied to the spot-size (cross sectional area) of the laser beam (W/m 2 ). Though only two variables (power and spot-size) are required to calculate the value of irradiation, two other important variables need to be considered when using lasers in surgery – time of exposure and wave length (or frequency). The use of lasers to generate heat for destroying tumors is known as ‘photo-thermal’ therapy. The changes caused by non-thermal mechanisms while using a laser are called ‘photo-chemical’ processes. Usually, in photo-chemical processes, the amount of irradiance is so low that, instead of generating heat, it induces chemical reactions in the cells thus causing inactivity. When the amount of irradiation is too high (10 8 to 10 9 W/cm 2 ), plasma formation takes place and leads to a ‘photo-plasmal’ process. If the electric field is too strong, the result is a small region of plasma which is associated with dielectric breakdown, strong electric fields, shockwave formation and tissue rupture. Once the plasma forms, the tissue properties become immaterial as all the laser energy is absorbed by the plasma itself [ 64 ]. Lasers can be classified into contact or non-contact types – based on their interaction with the tissue. In non-contact laser mechanism, the tip of the laser delivery device remains at a distance from the tissue to where it is being focused. When this kind of mechanism is used in a liquid medium, an explosive vapor bubble is formed at the tip of the tool which carries energy to the tissue. This type of energy delivery is preferred in a few ablation processes [ 65 ]. The contact laser is the direct contact of the tool tip with the tissue. This causes the direct transfer of energy from the tool to the tissue. The selection of a contact or non-contact laser depends upon the sensitivity and accessibility of the tissue being operated on. The most commonly used Laser devices are listed in Table 1 . Disadvantages of laparoscopic laser surgery include cost of specialized equipment, need for advanced training in laser and laparoscopic surgery, risk of fire from flammable materials ignited by lasers and increased operative time. The increased sedation period due to the length of the operative time also leads to longer recovery time. Cellular damage around the area of laser impingement can also be expected depending upon the size of the laser tip. One of the major complications using laser as the energy source is the air embolism which can be fatal [ 66 – 77 ]. Another complication with laser laparoscopic cholecystectomy is the injury to the hepatic artery with pseudoaneurysm formation and hemobilia [ 78 ]. Hemorrhage has been reported in other studies as well. In a review of 2344 laser laparoscopies over an 11-year period (1982 – 1993), Ewen et al. [ 79 ] reported nine significant complications in which three cases of intra-abdominal hemorrhage required laparotomies and one case of severe surgical emphysema during adhesiolysis with CO 2 laser was also reported. The efficiency of lasers in laparoscopy were reported as early as 1989, when Reddick et al. [ 80 ] studied 25 cases of laparoscopic cholecystectomy (in the US) and found no major complications despite having shorter recovery periods compared to open surgery. In laparoscopy, the major use of lasers is in gynaecological procedures, where it is commonly used in the treatment of infertility [ 81 – 86 ]. It is also a common source of energy in cosmetic and eye surgeries. Success rates of more than 90% have also been reported in review of cases that used CO 2 laser along bipolar forceps in laparoscopic surgery [ 87 , 88 ]. Advantages of laparoscopic laser surgery over open techniques include minimal surgical morbidity, decreased postoperative discomfort, and rapid, uncomplicated healing. Complications from laser laparoscopic surgery include air embolism, hemorrhage and surgical emphysema. Moreover a non-contact laser may do more damage than a contact laser [ 89 ]. Ward et al. [ 90 ] first reported the use of argon beam coagulation (ABC) in head and neck surgery in 1989. The use of ABC in MIS is first reported by Low et al. [ 91 ] in 1993. Numerous studies describing the efficiency as well as the dangers of ABC have been well documented [ 92 – 94 ]. In electrosurgery a radio frequency current is applied to tissue to cauterize and control bleeding. In ABC, a directed beam of argon gas from the electrode tip aids in conduction of the radio frequency current to the tissue by ionization. Like laser, this is a non-contact method where the argon gas - which is a good conductor of electricity - acts as a means of transportation of the current from the tool to the tissue. ABC performs faster than conventional coagulation systems and provides a more uniform and shallower coagulation region which results in faster dispersion thus minimizing tissue damage. It also produces less smoke than the conventional system. Since the argon has higher density, a jet of argon gas typically move the blood away from the surface for effective coagulation and resulting in lesser eschar. The protection of the active electrode tip from exposure to oxygen also results in less charring [ 95 ]. The ABC system is usually connected together with an electrosurgical system where argon gas is released from the tip of the tool to achieve hemostasis. The most commonly used ABC devices are listed in Table 1 . A major limitation to the use of ABC system is the potential danger of argon gas embolism. Numerous instances of cardiac arrest were reported during the use of ABC due to gas embolism [ 93 , 94 , 96 ]. Embolism (blockage of blood vessels) occurs due to the insolubility of the argon gas in blood. The gas forms bubbles or cavities that can travel through the blood stream and cause blockages in blood vessels. Death due to argon gas embolism has also been reported [ 97 – 99 ]. Cases of non fatal argon gas embolism have been reported in [ 100 – 104 ]. Despite the risks, ABC continues to be used in surgery. A number of successful cases in the use of ABC have been reported [ 105 – 109 ]. Dowling et al. [ 110 ] reported that the ABC was more effective in management of spleenic trauma compared to traditional techniques(topical surgical, electrocautery, suture-ligation, digital pressure) in a study on ten adult pigs. Guidelines for the safe use of ABC during laparoscopy have been tabulated by various researchers and commercial manufacturers. Some important guidelines are, The flow rate for argon should be chosen as low as possible to reduce the risk of argon gas embolism [ 111 ], direct contact of the tool tip on the organ should be avoided and the electrode tip should be held at an oblique angle. It was mentioned in a study that even at the point of longest application, the temperature developed while using ABC was never higher than 100°C in complete coagulation [ 112 ]. There are other studies such as the one by Bobbio et al. [ 113 ] wherein argon beam technique is compared with traditional surgery in the treatment of primary spontaneous pneumothorax (PSP) using video assisted thoracic surgery (VATS) where no significant benefits of ABC were found. The use of ABC has resulted in numerous cases of fatal and non fatal embolisms.. So, the use of ABC must solely depend on the skill and discretion of the surgeon. Electrosurgical generators can generate EM waves in a wide range of frequencies. Radio frequency or RF which ranges from 3 kHz to 300 MHz is the type of electromagnetic (EM) radiation that is commonly used in electrosurgery. RF has the lowest frequency of all the EM waves and hence takes longer than other EM waves to generate heat in the tissue. It has been shown in a number of studies that EM in the RF range is the most effective form of radiation. There are two mechanisms of RF that are used in MIS. One of them is the laparoscopic electrosurgical usage of RF. The mode of operation is the same as that of electrosurgery where the current applied to the tissue through the scalpel falls is the RF range. RF in electrosurgery can be used in both monopolar and bipolar modes. Apart from laparoscopy, RF can also be used in a percutaneous setting. Percutaneous treatment involves the insertion of a needle into the organ to be operated on via a catheter inserted through the skin of the patient. RF current is then applied to the tissue through the needle. Though it is different from laparoscopy, it is also a MIS procedure where the needle tip is usually guided into the body by an ultrasound positioning system. The most commonly used RF energy devices are listed in Table 1 . The most common usage of the RF in is radio-frequency ablation (RFA), which is also referred to as LRFA (laparoscopic radiofrequency ablation) in the laparoscopic setting. A number of studies show the application of LRFA in various procedures [ 17 , 19 , 114 ]. Beyer et al. [ 114 ] studied minimally invasive bipolar radiofrequency ablation of lone atrial fibrillation (AF) in 100 patients at 3 North American Institutes between 2005 and 2007 and reported postoperative complications that includes pacemaker requirement (5%), phrenic nerve palsy (3%), hemothorax (3%), transient ischemic attack (1%) and pulmonary embolism (1%). Case of deaths and high morbidity has also been reported in laparoscopic cholecystectomy procedure in Child-Pugh Class C Cirrhotic patients using a combination of HS dissection and radiofrequency coagulation [ 115 ]. In a report submitted to the American college of physicians in 2003, it was reported that RF ablation treatment of atrial fibrillation (arrhythmias) performed using a catheter can severely narrow the pulmonary veins due to the formation of scar tissues [ 116 ]. In rare cases, acute renal failure associated with radiofrequency liver ablation has been observed [ 117 ]. Most complications of RF seem to arise when it is used in the vicinity of the heart. This is due to the interference of the electrical with the electrical activity of the heart. Persistent inappropriate sinus tachycardia has been reported as a complication after radiofrequency (RF) ablation of the fast atrioventricular (AV) nodal pathway [ 118 ]. In a study of management of hepatic malignancies using RFA of malignant liver tumors in 608 patients between 1996 and 2002 [ 119 ], hepatocellular carcinoma, followed by colorectal adenocarcinoma were reported as a major early complications and. Symptomatic pleural effusion was reported as the major postoperative complication. In a study on advantages of using radio frequency (RF) heating over lasers for laser cartilage reshaping (LCR), it was shown that RF method allowed more uniform heating of larger tissue samples but the lack of precise control of spatio-temporal distribution of heat limits the usage of RF use in LCR [ 116 ]. The advantages of RF energy and the necessity to reduce complications have resulted in the introduction of several new commercial devices [ 120 , 121 ]. In [ 122 ], the Gyrus Plasma Trissector (GPT), a novel bipolar RF system in laparoscopic radical prostatectomies was shown to improve coagulation, reduce or eliminate sticking, seal large vessels and allow secure grasping and dissecting of tissue. Ligasure, a radio-frequency-energy-driven bipolar fusion device is used in many laparoscopic procedures [ 123 – 127 ]. For the minimally invasive treatment of localized renal tumor, RFA along with cryoablation is shown to be the most used and potentially promising therapies [ 128 ]. For the treatment of renal cell carcinoma, it was shown in [ 129 ] that RFA assisted laparoscopic partial nephrectomy was effective in providing hemostasis and in short term cancer control and also shown in [ 130 ] that RFA treatment for small renal cell carcinoma found have significantly improved the quality of life in most of the patients. In [ 131 ], it is also reported the reduction of intraoperative bleeding and blood transfusion using RF assisted laparoscopic liver resection. However, Hompes et al. [ 132 ] states that the laparoscopic liver resection itself is a procedure with minimal blood loss and that radiofrequency assistance has no additional advantage. In a comparative study between saline infused RFA and dry RFA [ 133 ], it was shown that wet RFA caused larger lesion sizes in 10 porcine kidneys and one cycle of wet RFA was sufficient to cause irreversible cell death compared to two cycles required using dry RFA. Although, percutaneous RFA in liver treatments is less invasive and is considered the first choice, RFA with laparoscopic guidance is highly recommended for patients with a relative contraindication for percutaneous RFA, such as lesions adjacent to the gastrointestinal tract, gallbladder, bile duct and heart [ 134 ]. Similarly, LRFA was also highly recommended for the treatment of hepatocellular carcinoma [ 135 ]. In general, the most usage of RFA either laparoscopically or percutaneously is observed in the liver and renal tumor ablation. However, a variety of studies featuring RFA in various surgeries also exists. RFA is reported in the treatment of lower extremity varicosities (a minimally invasive cosmetic procedure) where it fared better than stripping and foam sclerotherapy, although not as effective as laser therapy [ 136 ]. A study of bipolar RF in the treatment of plantar fasciosis [ 137 ] in patients who couldn’t be treated with conservative methods showed an improvement in all 10 patients within a time span of 6 months to 1 year without any postoperative complications. In a comparative study, it is important to understand the use of energy devices in the context of individual procedures. In this paper, we consider the laparoscopic cholecystectomy (LC) procedure an example ( Table 2 ). In LC the common energy sources used are laser, electrosurgery and ultrasonic energy. Since many of the case studies don’t explicitly state injuries occurred while using the energy device, for LC, parameters such as mean operating time, mean hospital stay, mean recovery time along with complications such as bile duct injury (BDI), bile leak, conversion rate to open surgery and any reported death were collected for each study and represented in Table 2 . From the data, HC and Ultrasonically Activated Scalpel (UAS) performed better than clip and electrosurgery methods based on operating time and bile duct injuries. Huscher et al. [ 138 ] sates that the main advantage of UAS is the low-risk dissection in the proximity of biliary structures. More over with UAS both cystic duct and vessels can be separated without the need for ligature. The relative bloodless field of view when using UAS also helps in discriminating anatomical structures. Redwan et al. [ 139 ] states that when comparing HS and clip and electrosurgery for LC, HS performed better with lesser operating time and the absence of major or minor bile leaks. No clear conclusion can be made regarding laser since the operating time and injuries when compared to clip and electrosurgery varied among the different studies and no direct comparison study exists between laser and ultrasonically activated devices. Between monopolar and bipolar electrosurgery, though both had comparable operating time, monopolar electrosurgery had more complications.

A comparative study of the literature shows that the preferred source of energy in laparoscopic surgery in the early 1990s was the monopolar electrosurgery, while bipolar and laser was used much less frequently. However, in recent times, even with the advent of new tools in electrosurgery, the preference is gradually shifting towards ultrasonic energy due to its many advantages in laparoscopy. While laparoscopic laser cholecystectomy, once a popular procedure, is rarely performed and harmonic scalpel (HS) has been used more often in recent times. Fiber optic cables have made lasers more readily available in laparoscopy. The use of lasers is most dominant in gynecological treatments like endometriosis. Argon beam coagulation (ABC) is a very effective technique to attain hemostasis, and despite the large number of deaths and intra-operative complications, it still remains in use. In spite of significant developments, the search for an ideal energy device that will result in perfect hemostasis with minimum damage to surrounding tissue in the most efficient manner posing the minimum threat to the patient in terms of short and long term complications remains elusive. Each energy method has advantages and disadvantages and a thorough knowledge of each devices is essential in deciding which energy source for be used for a specific procedure. Relative advantages and disadvantages of existing energy methods are presented in Table 3 . In a 2004 paper, Harrell et al. [ 140 ] mention that in a survey of 500 surgeons in 1993, 18% (of over 500 respondents) reported to have caused electrosurgical injury during laparoscopy and 54% reported to have known of another surgeon who has caused similar injury. Deaths were more common during early in era of laparoscopy. A brief search of the literature shows numerous instances of deaths in the 1980s using various energy sources. The number of deaths and even the complications in laparoscopy, have greatly reduced in recent times. For example, complications in laparoscopic cholecystectomy, which were reported to be around 2–4% in 1994 [ 141 ], came down to about 0.4% by 2005 [ 142 ]. Table 4 shows the various deaths reported in laparoscopy using energy sources. In general, most of the studies suggest that the effect of any laparoscopic procedure depends on the skill and familiarity of the surgeon with the surgical tools. An interesting observation while reviewing studies performed to test various instruments or methods is that some of the results seem contradicting. Devices which have been rated high by some studies have been rated low in others. Surgical skill and familiarity with the particular device may certainly be a possible contributor to this apparent paradox. Further, the devices which are shown to work well in the laboratory may not work the same way in an actual laparoscopic procedure. Hence, there is a need for developing uniform training regimens across surgical specialties under clinical conditions. Particularly, the fundamental understanding of how each of the energy devices work and their effect on the tissues is very important. For example, in electrosurgery, the understanding of different power settings and its effects on tissues is very important. More over the knowledge of safety issues with each of the devices should also be known so that appropriate precautions could be used to minimize injury. Solid communication and team coordination in high fire risk setting must be introduced into practice. Examples are the high temperature and low cooling rate of ultrasonically activated devices even after switched off, risk of air embolism in laser from high flow rate gas cooling and venous gas embolism while using ABC. A standardized curriculum or manual with working principles of various energy devices and their safety issues as envisioned by the FUSE program would be a valuable tool in increasing patient safety in surgical procedures using energy devices.

Each of the energy devices reviewed in this work had its own advantages and disadvantages. When considering thermal damage, monopolar electrosurgery results in the greatest amount of thermal damage to adjacent tissue while ultrasonic energy results in the least. In terms of their performance, ultrasonic devices provide the highest seal strength in smaller vessels, while electrosurgery is more efficient for larger vessels. Argon beam coagulation results in the most effective hemostasis on irregular surfaces, however, it also leads to gas embolism. In electrosurgery, RF is the most common form of electromagnetic radiation used followed by microwave radiation. Lasers are very expensive and are mostly limited to gynecological treatments in laparoscopy today, though at one time, they were widely used in many laparoscopic procedures such as cholecystectomy. In blood vessel sealing, the effectiveness of an energy device is dependent on the size of the blood vessel. Though there is no clear winner in terms of operating time, in the series of study that were reviewed in this work, the harmonic scalpel is shown to have reduced overall time compared to other energy sources in MIS. In terms of death from complications, lasers and ABC have more reported cases than the other methods and surgeons should be familiar in their use. Electrosurgery is still very popular in MIS due to its familiarity with surgeons and the development of various enhanced safety features to minimize injuries.

The vast majority of surgical procedures performed throughout the world involve the use of some device that applies energy to the tissue for cutting, coagulation, desiccation or fulguration for the destruction or manipulation of the tissue. While various energy sources including electricity, ultrasound, laser, argon gas, microwaves or radiofrequency waves may be used, the fundamental principle involves tissue necrosis and hemostasis by heating. The process of denaturation of tissue begins with the irreversible aggregation of macromolecules and the unraveling of collagen helices around 60ºC. Protein denaturation occurs between 70ºC and 80ºC resulting in coagulation. Further heating to 90ºC results in dehydration or dessication. Beyond 100ºC, the intercellular water boils, eventually vaporizing the cell allowing tissue cutting. Finally, tissue fulguration or carbonization occurs beyond 200ºC[ 1 ]. At present, there is no standardized curriculum for surgeons that address the physics, safe use and complications associated with these devices that promote the best outcomes for patients. In a recent study [ 2 ], it was found that many surgeons have knowledge gaps in the safe use of widely used energy-based devices. To address this issue, the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) has recently initiated the Fundamental Use of Surgical Energy (FUSE) program to develop an educational curriculum that will cover both didactic and hands-on training approaches to the use of energy in interventional procedures in the operating room and endoscopic procedure areas. The goals are to prevent untoward events such as operating room fire, patient injury, surgeon/staff injury as well as promoting optimal use. The purpose of this paper is to summarize some of the major energy sources used in laparoscopic surgery and discuss their relative advantages and disadvantages.