Effectiveness of the ultrasonic harmonic scalpel for tonsillectomy.

Abstract

The Ultracision harmonic scalpel (UHS) cuts and coagulates tissue with high-frequency ultrasound. We describe the results of our use of the UHS to perform tonsillectomies in 59 patients. The mean operative blood loss was 7 ml (range: 0 to 75); 56% of patients experienced no measurable blood loss. The mean length of operating time was 8 minutes and 10 seconds (range: 3:45 to 20:25). Patients were assessed for 2 weeks for postoperative pain on the basis of a 10-point linear analog scale. The mean pain score on postoperative day 1 was 4.7; the score peaked at 6.0 on day 4 and fell to less than 3.0 by day 11. Patients returned to full function in an average of 10.9 days (range: 3 to 15). Three patients experienced secondary hemorrhage, one of whom required surgical intervention. We found the UHS to be a well-designed and easy-to-use instrument. Operating time was short, blood loss was minimal, and the degree of early postoperative pain was low. We believe that our findings are encouraging and that the UHS might w ell have a place in the surgical armamentarium for tonsillectomy.

Introduction

Various tonsillectomy techniques described over the years include guillotine excision, blunt dissection, bipolar diathermy dissection, laser dissection, and the bipolar scissor technique. [1-6] The ultrasonic harmonic scalpel (UHS [Ultracision; Ethicon Endo-Surgery; Cincinnati]) has been used in urologic, thoracic, hepatic, laparoscopic, and gynecologic procedures over the past few years, but its use in ENT surgery has not been reported. In this article, we describe the outcomes of our use of this technique in performing tonsillectomies in 59 patients.

Materials and methods

We studied 59 consecutive patients, aged 2 to 62 years (mean: 13.7; 76% younger than 14), who underwent routine tonsillectomy for recurrent tonsillitis at two centers in England. Surgery was performed by one of the authors (S.S.) at the Huddersfield Royal Infirmary in Huddersfield and by another of the authors (R.C.) at the Radcliffe Infirmary in Oxford; both surgeons are of Specialist Registrar grade.

Study parameters. We measured the length of the operating time from the moment the initial incision was made until the moment the Boyle-Davis gag was removed. We estimated the amount of blood loss by weighing swabs before and after each procedure; each 1 g of additional weight was considered to equal 1 ml of blood. We also noted the length of time that had passed before each patient was able to eat.

We quantified the degree of immediate postoperative pain on a linear analog scale, which ranged from 0 (no pain at all) to 10 (the most pain that the patient had ever experienced). All patients were asked to rate their pain on the morning after the procedure and for 2 weeks following discharge. At the end of the 2 weeks, patients' pain scores were obtained by telephone or in the outpatient department. We also recorded the number of doses of analgesia that were administered prior to discharge. All patients were discharged on the first postoperative day.

The ultrasonic harmonic scalpel. The UHS components include a generator, a handpiece, and a hook-shaped blade (figure 1). Energy is generated by a microprocessor-controlled high-frequency power supply that delivers alternating current to the handpiece. Application of current across a transducer in the handpiece causes the blade to vibrate at its harmonic frequency of 55,000 Hz. The generator's power can be set between 1 and 5; we used level 3 for our tonsillectomies. Higher settings increase the amplitude of blade vibration and produce a larger cutting area, which enables a more rapid dissection but less coagulation. The maximum cutting effect is achieved when the generator is set at level 5, and the maximum hemostatic effect is achieved at level 1.

The scalpel cuts in two ways: by cavitation of tissues and by mechanical disruption. The mechanical oscillations of the blade tip cause internal tissue pressures to rise and fall rapidly, and the cavities within the cells fill with vapor. The expansion and contraction of these cavities results in tissue dissection. Low-density tissues are thus disrupted by a process of cavitational fragmentation in which the tissue planes separate ahead of the blade tip. As dissection progresses, the surgeon feels the sensation of "cutting through soft butter."

The UHS controls hemorrhage by "coaptive coagulation"--that is, the ultrasonic energy denatures protein into a sticky coagulum that seals bleeding tissues and blood vessels up to 5 mm in diameter. Keeping the blade in contact with the tissue for prolonged periods results in deeper coagulation. This is in contrast to the electrical and laser techniques, in which intense local heat destroys tissue by desiccating and charring it and produces hemostasis by obliterative coagulation. During UHS surgery, there is little lateral distribution of energy, so damage to surrounding normal tissues is minimal. Tissue temperatures rise to only 65 to 100[degrees] C, which is considerably lower than the temperatures reached during diathermy and laser surgery.

Both of the surgeons found that the harmonic scalpel was easy to use and that cutting and coagulation were easy to control. However, contact of the rapidly vibrating blade with larger vessels caused blood to spray, so we recommend wearing eye protection.

Results

Our results are summarized in the table. Highlights:

Operating time. The average operation lasted only 8 minutes and 10 seconds; the quickest was only 3 minutes and 45 seconds.

Blood loss. The amount of intraoperative blood loss ranged from 0 to 75 ml (mean: 7.0); 33 patients (56%) had no measurable loss. There were no cases of primary hemorrhage, but three patients were readmitted with secondary hemorrhage on postoperative days 5, 6, and 7. One of these patients required further surgery to achieve hemostasis, and the other two were managed conservatively.

Ability to eat. The mean time to the first postoperative food intake was 6 hours and 18 minutes. This figure might have been skewed by the fact that some patients who were operated on at the end of an afternoon were not offered food until the next morning.

Pain. For postoperative analgesia, children were prescribed acetaminophen and/or ibuprofen and adults received acetaminophen/codeine and/or diclofenac. Their mean pain score on the morning following the procedure was 4.7 (figure 2). The mean pain score increased during the next few days and peaked on postoperative day 4 (mean: 6.0). By day 11, most patients reported a score of 3 or less.

Five patients returned to the ward following discharge complaining of severe pain--two on postoperative day 2 and three on postoperative day 6 or 7. All five were readmitted for pain control. They were treated with oral acetaminophen, codeine, and diclofenac; two of these patients required overnight intravenous fluids. All five were discharged within 48 hours of readmission.

Discussion

Advocates of cold dissection tonsillectomy suggest that it results in more rapid healing and causes less pain than does electrosurgery. [2,7,8]] Bipolar diathermy dissection remains popular because of its short operating time and minimal perioperative blood loss. However, diathermy is associated with thermal damage to the surrounding normal soft tissues, which might explain why it results in more pain than does cold dissection. [3]

Favorable results with the harmonic scalpel have been reported in other surgical specialties. [9] We found it to be a well-designed and easy-to-use instrument for tonsillectomy. In our case, the surgical learning curve was steep, and both surgeons were satisfied that they were able to use the scalpel efficiently after only two or three cases.

The results of our preliminary study show that in terms of operating time and blood loss, the UHS is comparable to diathermy and laser surgery and compares favorably with traditional blunt dissection. [1,7,10-12] It also has advantages over diathermy in that it does not require a ground electrode pad, it does not cause nerve stimulation, it reduces the thermal effects to surrounding tissues, and it obviates problems associated with electrical current leakage.

Although the immediate postoperative pain scores in our study were relatively low, we were somewhat disappointed with the relatively high readmission rate (8.5%) for late pain control. It could be that we inadvertently introduced a bias into this study when we advised our patients that if they had any postoperative problems, they should return to the ENT ward rather than visit their general practitioner. Five adults did return, complaining that their pain was not being controlled by their discharge analgesics. These patients requested to be hospitalized for bed rest and alternative oral analgesia. We believe that a small but consistent proportion of patients always seeks a medical opinion during the first week after any method of tonsillectomy, and these patients usually see their general practitioner, who will usually prescribe alternative analgesia.

We were impressed by the lack of pain on the first postoperative day and the fact that most patients were eating within a few hours of the procedure. These findings might be of particular benefit to patients who undergo day-case tonsillectomy. The subsequent daily pain scores, which peaked on day 4, reflect the usual pattern following tonsillectomy. However, it is possible that the peak we witnessed was more prominent given the relative absence of pain during the first few postoperative days.

The UHS procedure is more expensive than traditional methods of tonsillectomy, primarily because the generator costs approximately [pound]20,000 ([sim]$29,000 U.S.) and each disposable blade costs [pound]75 ([sim]$108 U.S.). The higher cost might be offset by savings associated with day-case surgery and the short operating time.

The UHS might well have a useful place in the tonsillectomy armamentarium. However, we realize that a formal prospective, randomized, controlled study is required to confirm our findings and to compare UHS tonsillectomy with other methods. In light of the encouraging results of our pilot study, we are currently planning such a trial.

Acknowledgment

We thank Dr. Abou-Hassoun for assisting with the collection of data.

References

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(9.) Tomita Y, Koike H, Takahashi K, et al. Use of the harmonic scalpel for nephron sparing surgery in renal cell carcinoma. J Urol 1998;159:2063-4.

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Table. Results of UHS surgery in 59 patients
                              Median         Mean
Operating time                7 min, 50 sec  8 min, 10 sec
Intraoperative blood loss     0.5 ml         7.0 ml
Time to first food intake     4 hr           6 hr, 18 min
Return to normal diet         7 days         7.6 days
Analgesia prior to discharge  6 doses        5.8 doses
First-postop-day pain score   4.0            4.7
Return to normal function     11 days        10.9 days
                              Range
Operating time                3 min, 45 sec
                              to 20 min, 25 sec
Intraoperative blood loss     0 to 75 ml
Time to first food intake     1 hr, 30 min to 18 hr
Return to normal diet         1 to 15 days
Analgesia prior to discharge  1 to 12 doses
First-postop-day pain score   0 to 8
Return to normal function     3 to 15 days

[Graph omitted]