Tuesday, July 07, 2009

Tonsillectomy New Vistas

Introduction: History of tonsillectomy dates back to nearly 2000 years. It was Celsius who first described the procedure in the first century A.D. The potentials for complications after this surgical procedure are still very high despite the advancements in technology. There is still no consensus between the otolaryngologists regarding the safest operating technique which is not attended by any of the classic post operative complications described after tonsillectomy.
None of the evaluated procedures has clearly shown that post operative pain could be minimized. The cause for post operative pain following tonsillectomy is due to disruption with exposure of underlying nerve endings (glossopharyngeal and vagus), and pharyngeal constrictor muscle fibres. Postoperatively exposed to external elements the exposed muscle fibres undergo spasm causing pain while swallowing. Any newer surgical technique should address this aspect of inflammation involving the pharyngeal constrictor muscles.

Subtotal intracapsular tonsillectomy:

This concept is based on minimal tissue injury. The pharyngeal constrictor muscles are not exposed. The raw nerve endings are also not exposed to the environment. The post operative pain after this procedure is very minimal and the patient undergoes a stress free convalescence period. In this procedure radio frequency probe is used. This technique is also known as “Temperature controlled radiofrequency tonsil reduction”. In this technique a RF probe is introduced into the tonsillar tissue and heated up to 40 - 70° C. A plasma field containing highly ionized particles is formed at the probe’s surface causing tissue destruction. This probe can thus be used to create small channels in the tonsil with dissipation of the energy released by ionizing radiations. This causes tissue destruction during the following days / weeks of surgery leading on to a gradual reduction in the size of tonsillar tissue. Initially there is an increase in the size of tonsil due to soft tissue oedema. Tonsil shrinkage usually occurs between the first and third weeks. The main advantage of this procedure is that since the tonsillar bed structures are minimally damaged, these patients are absolutely pain free even on the first post operative day.

Advantages of radiofrequency probe versus conventional diathermy / electrocautery:

  1. Radiofrequency generators operate at lower frequencies than conventional electrocautery units. The cutting action of R.F. cautery occurs at 70° C. This is much lower than the cutting temperature of conventional electro cautery units which ranges between 400 – 500 º C.
  2. The high current density which is released by the electrode causes a rapid increase in the local temperature ranging from 50 – 80 ° C. This raise in temperature causes coagulation, protein denaturation and irreversible tissue destruction. When the tissue temperature reaches the critical level of 100 º C boiling occurs at the electrode tissue interface. This boiling causes the tissue coagulum to adhere to the electrodes disrupting the current flow through the prongs.
  3. Radiofrequency ablation uses frictional heating that is caused when the ions in the tissue attempts to follow the changing directions of alternating current.
  4. These devises have sensors close to their tip which are capable of monitoring tissue temperatures. When the local tissue temperature reaches 100 º C the sensor automatically shuts off the current to the generator ensuring that the tissue temperature does not exceed 100 ° C.

During RF tonsillectomy the cutting mode should be paused for 10 seconds for every 10 seconds of tissue cutting.

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