New Ultrasonic Dissector Versus Conventional Hemostasis in Thyroid Surgery: A Randomized Prospective Study

Abstract

Background:

The ultrasonic dissector (UD) is an instrument that uses vibration to coagulate and cut tissue simultaneously. The main advantage of a UD instrument compared with a standard electrosurgical device is represented by minimal lateral thermic tissue damage allowing a wide application in thyroid surgery. A new UD (NUD), with a tip smaller than 5 mm, might enable a more precise dissection near vital structures such as parathyroid glands and recurrent laryngeal nerve. To evaluate the NUD during thyroid surgery, a prospective randomized study was performed using the new device versus traditional procedures.

Subjects and Methods:

Two hundred sixty-one patients underwent various thyroid surgical procedures; they were randomly assigned (130 in the NUD group and 131 in the conventional hemostasis [CH] group). The two surgical groups were compared in age, sex, diagnosis, thyroid size, operative time, drainage volume during the first 24–48 hours after surgery, and complications (hypoparathyroidism, damage of the recurrent laryngeal nerve, and postoperative pain).

Results:

The two groups were similar regarding age, sex, numbers of lobectomies and total thyroidectomies, and numbers of focal and diffuse pathologies. Mean±standard deviation operative time was shorter in the NUD group compared with the CH group for both lobectomy (70±21 minutes versus 99±27 minutes; P<.01) and total thyroidectomy (91±37 minutes versus 121±42 minutes; P=.01) procedures. No difference was found regarding the amount of drainage volume for different procedures (P=not significant). Postoperative transient (P=.01) and definitive (P=.01) hypoparathyroidism occurred more frequently in the CH group than in the NUD group. There was a significant difference regarding the transient damage of the recurrent laryngeal nerve: 7 patients (5.3%) in the NUD group and 13 patients (9.8%) in the CH group (P=.01). There was no difference regarding definitive damage to the recurrent laryngeal nerve and pain.

Conclusion:

This NUD may reduce the rate of complications (transient and definitive hypocalcemia, transient damage of the recurrent laryngeal nerve) and operative time.

Introduction

The ultrasonic dissector (UD) has found wide application in the context of laparoscopic,^1–4 thoracoscopic,^5,6 and other surgical^7,8 procedures. In thyroid surgery, the UD has been used in both open⁹ and video-assisted¹⁰ approaches.

The Harmonic^® scalpel (Ethicon Endo-Surgery, Cincinnati, OH) is an instrument that uses vibration to coagulate and cut tissue¹¹ simultaneously. The main advantages of ultrasonic coagulating and dissecting systems compared with a standard electrosurgical device are represented by minimal lateral thermal tissue damage (the UD causes lateral thermal injury 1–3 mm wide, approximately half of that caused by bipolar systems), less smoke formation, no neuromuscular stimulation, and no electrical energy to or through the patients.¹²

Thyroidectomy is, basically, a devascularization of the thyroid by double ligating and dividing the branches of the thyroid vessels followed by excision of the gland, as done in all resectional surgical procedures. The unique feature of this operation is that the thyroid gland is one of the most vascularized organs because of the many blood vessels and plexuses within its parenchyma. These vessels need to be controlled with ligatures. The ligation and division of the vessels are time consuming. The time spent with the conventional clamp-and-tie technique can significantly be reduced following the ultrasonic procedure. Because the time spent in the operating room is expensive,¹³ this will decrease both the operation time and the operative costs. Thus, the use of the UD could lead to a significant reduction of the operative time in thyroid surgery. Despite their safety and effectiveness in thyroid surgery, the previous UD instruments are considered large and cumbersome by several surgeons.

A new UD (NUD) handpiece (FOCUS^®, Ethicon Endo-Surgery), with a tip smaller than 5 mm, has been made available since 2008. This NUD might ensure a more precise dissection near vital structures and be safer for parathyroid glands and the recurrent laryngeal nerve, but clinical randomized studies using this device are still few.^14,15 To better explore these aspects, the present prospective randomized trial study has been designed to evaluate the effectiveness and safety of the NUD compared with conventional hemostasis (CH) in open thyroid surgery.

Subjects and Methods

Between January 2008 and March 2011 we conducted a prospective randomized study on 261 consecutive patients (60 men, 201 women; mean age, 50 years) who underwent various thyroid surgical procedures performed by two of the authors (G.A. and M.S.).

Exclusion criteria included patients with previous neck surgery, those with extrathyroidal invasion of malignant thyroid tumors, and those undergoing an accompanying additional procedure (i.e., parathyroidectomy, lymph node dissection).

Patients were randomly assigned to either the NUD group, in which the operation was performed entirely using the NUD and no other hemostatic tool (130 patients), or the CH group, in which the operation was performed using CH techniques such as the reabsorbable ligature and monopolar and/or bipolar diathermy (131 patients); those patients underwent either lobectomy or total thyroidectomy (Table 1).

Table 1.

Characteristics of the Surgical Groups

Parameter	Harmonic Focus	CH
Number of patients	130	131
Age (years) [mean (range)]	49.3 (32–76)	51.1 (39–78)
Sex (female/male)	99/31	102/29
Lobectomy (total)	11	9
Right	6	4
Left	5	5
Total thyroidectomy	119	122
Pathologic diagnosis
Focal pathologies	24	24
Benign tumors	11	9
Malignant tumors	13	15
Diffuse pathologies	106	106
Goiter	94	91
Thyroiditis	7	8
Basedow's syndrome	5	7

CH, conventional hemostasis.

Surgical technique with the NUD

The skin incision with NUD may be about 4 cm, if the size of the thyroid is not excessive, compared with 8–10 cm in the conventional resection^16,17; in fact, the easy handling of the instrument (cutting and coagulating at the same time) ensures a better preparation of the upper vascular poles, avoiding wider cutaneous incisions.

The NUD performs a bloodless dissection of both the upper and lower edges of cervicotomy, the etching of the deep cervical aponeurosis and of the linea alba of the pre-thyroid muscles with the clotting of the veins to bridge among the anterior jugular and the subcutaneous vessels. This also ensures a faster closure of cervicotomy and avoids lasting hemostasis. NUD also ensures an easier preparation of the upper vascular pole by the coagulation–dissection of the apical, juxtapolar part of the sternothyroid muscle.

The preparation of the lobe is made easier by the rapid section of the middle thyroid veins with the NUD, compared with traditional methods. However, preparation of the common carotid artery, the lateral border for the examination of the recurrent laryngeal nerve, must be done with caution because of the low sensitivity of the NUD compared with the scissor in the tissue dissection; its ability to cut is in fact indifferent to the consistency of the tissues with a dangerous result, as may occur in the drilling of this vessel. Therefore it is necessary to raise, between branches of the NUD, cell tissue surrounding the vessel, coagulating it and isolating it at a distance.

For the same reasons, the examination and preparation of the recurrent laryngeal nerve must be carried out with a classic dissector, and the NUD must be used only to dissect the pre-neural plate once prepared and raised approximately 5–6 cm.^18,19

Once the pre-thyroid fascia and the recurrent laryngeal nerve are isolated, the NUD allows proceeding with a much quicker and bloodless dissection in full. However, use of the NUD must be avoided at the level of the cricopharyngeus muscle under which the recurrent laryngeal nerve penetrates, especially in the case, which is not rare, of a voluminous parenchymal Zuckerkandl's tubercle.

The NUD also quickens the liberation of the lower thyroid pole by coagulation–section of the many vessels directly connected to the parenchymal tissue of the superior mediastinum. The release of the contralateral lobe is similar. Finally, the NUD is much easier to use in the dissection of Gruber's ligament and the pyramidal lobe, if it is present, for its ability to insinuate into narrow spaces such as near the hyoid bone. The end times are the same as those described for the traditional technique.

The two surgical groups were compared regarding age, sex, diagnosis (Table 1), thyroid size, operative time, fluid content in the suction balloon (drainage volume) during the first 24–48 hours after surgery (Table 2), and complications (Table 3) using a two-tailed t test, chi squared test, and Wilcoxon rank sum test. Statistical significance was reached at P<0.05.

Table 2.

Intervention Results of the Surgical Groups

Parameter	Harmonic Focus	CH
Thyroid size (cm)
Lobectomy	4.8±2.3	3.9±1.9
Total thyroidectomy	6.7±4.2	5.2±3.2
Operative time (minutes)
Lobectomy	70±21	99±27
Total thyroidectomy	91±37	121±42
Drainage volume (mL)
Day 1
Lobectomy	81±18	85±21
Total thyroidectomy	93±21	91±18
Day 2
Lobectomy	33±7	35±9
Total thyroidectomy	40±11	43±13

Table 3.

Complications of the Surgical Groups

	Number of patients (%)
Parameter	Harmonic Focus	CH
Recurrent laryngeal nerve damage
Transient	7 (5.3%)	13 (9.8%)
Definitive	—	2 (1.5%)
Hypoparathyroidism
Transient	15 (11.5%)	43 (32.8%)
Definitive	1 (0.7%)	5 (3.8%)
Wound infection	2 (1.5%)	—
Postoperative hospitalization (days)	2.3 (1–4)	2.4 (2–4)

Suction drainage was used to evaluate the overall amount of blood loss after the procedure and to assess the actual difference between the groups. The drains were removed 24–48 hours after surgery.

No additional time was spent in any case to wait for the frozen section pathology report. Subtotal or near subtotal thyroidectomies were also considered under total thyroidectomy cases for practical reason.

If patients reported a postoperative pain score of more than 3 cm on a 10-cm visual analog scale (where 0 cm indicates no pain and 10 cm indicates the worst pain imaginable), they were administered intramuscular ketorolac tromethamine (30 mg i.m. every 6 hours).

All patients were followed up with office visits 2 weeks after surgery. The ethical committee of the Department of Surgery at the University of L'Aquila approved the study protocol. All patients gave informed written consent.

Results

The two groups were similar in age, sex, numbers of lobectomy (right and left) and total thyroidectomy, and numbers of focal and diffuse pathologies (Table 1).

There were no intraoperative complications. Mean±standard deviation thyroid size tended to be larger in the NUD group for both lobectomy (4.8±2.3 cm versus 3.9±1.9 cm; P=.06) and total thyroidectomy (6.7±4.2 cm versus 5.2±3.2 cm; P=.08) specimens compared with the conventional technique (Table 2).

Mean±standard deviation operative time was shorter in the NUD group compared with the CH group for both lobectomy (70±21 minutes versus 99±27 minutes; P<.01) and total thyroidectomy (91±37 minutes versus 121±42 minutes; P=.01) procedures (Table 2).

There was no difference between the two techniques regarding the amount of drainage volume for different procedures (P=not significant). Additional knotting or electrocauterization was not necessary in the NUD group. Postoperative transient biochemical hypoparathyroidism occurred more frequently in the CH group than in the NUD group (Table 3). Biochemical hypoparathyroidism was defined as a serum calcium level below 8.1 mg/dL (reference range, 8.1–10.4 mg/dL). In the NUD group and in the CH group, 15 patients (11.5%) and 43 patients (32.8%), respectively, required postoperative oral calcium carbonate supplementation, although these patients showed no clinical symptoms of hypocalcemia. This difference was statistically significant (P=.01) (Table 3). The lowest serum calcium level was 7.5 mg/dL in the CH group versus 7.7 mg/dL in the NUD group. Also, postoperative definitive hypoparathyroidism occurred more frequently in the CH group (5 patients [3.8%]) than in the NUD group (1 patient [0.7%]). This difference was statistically significant (P<.01) (Table 2).

Transient damage of the recurrent laryngeal nerve occurred in both the NUD group and the CH group: 7 patients (5.3%) and 13 patients (9.8%), respectively. This difference was statistically significant (P=.01) (Table 3). Definitive damage of the recurrent laryngeal nerve occurred in 2 patients (1.5%) of the CH group (P=not significant).

Two patients (1.5%) in the NUD group experienced a wound infection (P=not significant). These patients were treated conservatively with daily medications, local drainage, and antibiotic therapy.

The mean postoperative hospital stay was similar in both groups (mean, 2.3 days).

According to the visual analog scale scores, patients in the NUD group experienced less pain (but not significantly) compared with patients in the CH group.

Discussion

In endoscopic surgery (digestive, gynecologic, urologic, or thoracic), the UD has shown specific benefits in reducing bleeding and operating time.^20–23

Regarding thyroid surgery, Voutilainen et al.¹⁹ observed a mean advantage of 54 minutes with the use of the UD versus the use of the conventional technique in an initial matched-pair study for thyroidectomy (n=6 pairs) and lobectomy (n=1 pair). This research group subsequently randomized 36 patients undergoing thyroidectomy or lobectomy into ultrasonically activated shears (n=19) and conventional surgery (n=17) groups.⁹ The study of Voutilainen and Haglund⁹ reported that average operating room time saving with the UD was 35.8 minutes, with no difference in complication between the UD and traditional groups.

In a French study, Meurisse et al.³ randomized 34 patients with euthyroid multinodular goiter undergoing total thyroidectomy to either the UD or CH group and demonstrated an average 26-minute reduction in operating time as well as reductions in blood loss, postoperative analgesic consumption, and incidence of transient hypothyroidism.

Siperstein et al.²⁴ observed a mean advantage of 30 minutes with the use of the UD versus the use of CH. Miccoli et al.²⁵ confirmed these data (a mean time reduction of 14.3%).

Our experience showed that the use of the NUD for the control of thyroid vessels during thyroid surgery is safe and that it shortens the operative time by almost 36 minutes compared with CH for both unilateral lobectomy or total thyroidectomy procedures despite the large size of the thyroid removed with the NUD. The NUD device offers tissue dissection capabilities and can be used in several intraoperative steps. We found it useful for the dissection of the true capsule from the false capsule, especially in the lateral side of the thyroid and of Berry's ligament. In contrast, tissue dissection cannot be achieved easily with the UD.

In a prospective randomized study, Markogiannakis et al.¹⁴ compared the results of total thyroidectomy using the NUD with those of the previously available device. The mean operative time was less in Group A (NUD) than in Group B (previously available device) (63±7 minutes versus 76±8 minutes; P=.009).

Our data demonstrate that the complication rate in the NUD group might be significantly reduced. This could be evaluated for transient hypocalcemia (11.5% versus 32.8%; P=.01), definitive hypocalcemia (0.7% versus 3.8%; P=.01), and transient (5.3% versus 9.8%; P<.01), and definitive (0% versus 1.5%; P=not significant) recurrent nerve palsy. The incidence of definitive recurrent nerve palsy was too low to reach statistical significance in this type of prospective study. Similar results for transient hypocalcemia were reported by Miccoli et al.²⁵ (10% versus 32%; P=0.01) and by Meurisse et al.,³ although their results were not statistically significant. Our results seem to support the hypothesis stated by Cordón et al.²⁶ that the reduced level of injured tissue resulting from less heat generated by the NUD might lead to a reduced risk of impaired vascularity in the parathyroid glands.

In the study of Pons et al.²⁷ no definitive complications arose. The three cases of hypocalcemia were transient. The two cases of vocal cord palsy were also transient. However, other series have reported an increase in the number of recurrent nerve injuries and instances of hypocalcemia when using the UD or other devices.²⁸ Thus, every possible precaution should be taken when using these tools. When in use, the tip of the instrument is hot and can damage structures (nerve, vascular tissue, muscular tissue, or even skin) with the slightest contact. It is therefore necessary to regularly plunge the tip of the instrument into cold serum or wipe it on a compress saturated with cold serum. Furthermore, when the dissection is performed close to the recurrent nerve, thermal diffusion (on the order of 2 mm)^29–31 requires that the examination and preparation of the recurrent laryngeal nerve be carried out with the classic dissector and that the new Harmonic scalpel must be used only to dissect the pre-neural plate once prepared and raised approximately 5–6 cm^18,19 (see Surgical technique with the NUD).

The reduction of postoperative pain in patients in the NUD group was not significant. This factor has been rarely examined,^3,25 and the results are controversial, probably because of the difficulty of evaluating objectively such an outcome.

On the other hand, the cost of the Harmonic scalpel is a crucial point: The UD is disposable and expensive and must be considered as an additional cost in the Medicare hospital payment system.³² However, when the reduced operative time and the reduced complication rate are considered, the device actually might be cost-effective.⁴ Sebag et al.³³ have demonstrated that the safety and efficiency of the UD are comparable to those of the tie-and-clip technique in thyroid surgery; the use of the UD in multinodular goiter surgery ensures a significant reduction in the length of the procedure with a comparable cost (mean operative cost per patient was 990 euros [standard deviation, 191] in the conventional tie-and-clip group and 1,024 euros [standard deviation, 143] in the NUD group [P=not significant]). Lombardi et al.³⁴ have demonstrated that the cost of disposable materials is significantly higher in the UD group (420.1±23.2 euros for the UD group and 137.8±25.3 euros for the knot-tying technique group [P<.001]). Conversely, drugs, staff and operative room charges were significantly higher among knot-tying technique group patients (P<.001). On the whole, no significant difference was found between the two groups concerning the charges for the hospitalization (P=not significant).

Disposable UDs (SonoSurg Olympus, Tokyo, Japan) are available on the market. Recent studies have shown that the effectiveness of sterilizable and nonsterilizable UDs in coagulating arterial vessels up to 4 mm in diameter^35,36 is the same.

It is possible to sterilize the disposable UD up to eight to 10 times, allowing a reduction of operating costs.³⁷ Nevertheless, the disposable UDs on the market have been conceived for open abdominal surgery or for laparoscopy. There are no sterilizable UDs for thyroid surgery. Their production would mean a further cost reduction.

Conclusions

The NUD is a useful adjunct to the armamentarium of the thyroid surgeon. It is safe, effective, and hand-friendly, offering great capabilities for delicate tissue grasping and dissection than traditional approaches.¹⁴ The use of this device may reduce the rate of complication (transient and definitive hypocalcemia, transient damage of the recurrent laryngeal nerve) and operative time by almost 36 minutes compared with CH for both unilateral lobectomy or total thyroidectomy procedures. As the next step, we are starting a randomized clinical trial to further assess the use of the NUD in total thyroidectomy with modified neck dissection.³⁸

Footnotes

Disclosure Statement

No competing financial interests exist.

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