A harmonic scalpel is a piece of medical equipment used in surgical procedures as an option to a steel scalpel or electro-surgical diathermy. It uses ultrasound technology to cut tissues while simultaneously sealing the edges of the cut. The system typically is composed of a hand-held ultrasonic transducer, generator, hand switch, foot pedal, and scalpel that serves as the cutting instrument.
The instrument is similar to a surgical diathermy, but advocates suggest it is superior in that it can cut through thicker tissue, creates less smoke, and may offer greater precision. However, the harmonic scalpel is not as easily manoeuvrable, and takes longer to cut and coagulate tissue. Additionally, while a surgical diathermy can be used to coagulate bleeding tissue at any time, the Harmonic scalpel only coagulates as it cuts.
The 'Harmonic scalpel" causes less lateral thermal damage than the "Surgical diathermy".
Whereas a Surgical diathermy performs its action via an electrical current (and production of heat), the Harmonic scalpel cuts via vibration. The scalpel surface itself cuts through tissue by vibrating in the range of 20,000Hz to 60,000Hz. The vibration cuts through the tissue and seals it using protein denaturisation, rather than heat. A good analogy is whisking an egg white; denaturisation of the protein by vibration rather than heat.
Medical procedures that can be performed using the harmonic scalpel include thyroidectomy, lung biopsy, laparoscopic cyst decortication, tonsillectomy, and gynaecologic cancer. Many plastic surgeons have also found that it is a better system to performing plastic surgery, such as a face-lift, breast reduction, breast augmentation, or tummy tuck.
Various tonsillectomy techniques described over the years include guillotine excision, blunt dissection, bipolar diathermy dissection, laser dissection, and the bipolar scissor technique. The ultrasonic harmonic scalpel has been used in urologic, thoracic, hepatic, laparoscopic, and gynaecologic procedures over the past few years, but its use in ENT surgery has not been widely reported.
Tonsillectomy has been a known surgical procedure for almost 2,000 years. The first cases were described by Celsus as early as 50 AD. As recently as the early 20th century, it was believed that tonsillitis was caused by various systemic disorders (e.g., rheumatoid arthritis). Proponents of tonsillectomy also began to use the procedure to treat such conditions as mental retardation and anorexia and to use it simply as a measure to promote good general health. Perhaps the ultimate in enthusiasm for tonsillectomy and adenoidectomy was manifested by certain communities in Russia, where wholesale surgery was performed on entire populations of school children in public school buildings.
The decline of tonsillectomy despite a growing population appears to be attributable to advances in antimicrobial therapy, more definitive criteria for surgical intervention, and a heightened respect on the part of physicians for cost-risk-benefit considerations.
The indications for tonsillectomy are numerous. The most widely accepted include: recurrent infections; obstructive sleep apnoea; peritonsillar abscess with recurrent tonsillitis; malignancy or suspected malignancy; and tonsillitis that has caused febrile seizures. Until the late 1960s, tonsillectomies were performed by cold surgical dissection, where the tonsil is removed from its capsular plane by blunt and sharp dissection. In the 1970s, many surgeons found that hot electrocautery was safe, easy to perform, and offered good control of intraoperative haemorrhage. In fact, monopolar electrocautery dissection is one of the most common procedures in use today.
Innovation and research continue to lead to improvements in the efficacy, safety, and cost of tonsillectomy. One such innovation is the ultrasonic harmonic scalpel, which was introduced in 1993 (Ethicon Endo-Surgery) and which is becoming increasingly popular as a tonsillectomy device.
The harmonic scalpel has been shown to be a valuable tool for numerous surgical procedures, including cholecystectomy, bowel resection, and adhesiolysis. The instrument minimizes lateral thermal tissue damage. There is almost no need for instrument changes. The reasons for the increasing popularity of the harmonic scalpel are its purported associations with less postoperative pain and an earlier return to oral intake and regular activities.