A patient has undergone a total thyroidectomy what postoperative care does the nurse provide

Thyroidectomy: Technical Considerations

Disease recurrence and survival rates for resectable thyroid cancers are directly related to completeness of resection and an R0 resection should thus be attempted whenever possible. The surgeon should therefore be prepared for possible en bloc resection of involved structures, most commonly the strap musculature, followed by the ipsilateral RLN, the trachea, the esophagus, the larynx and the ipsilateral internal jugular vein. Residual tumor should not be left in situ under the assumption that this tissue will be destroyed by adjuvant RAI therapy, which may not clear such disease. Careful intraoperative inspection and palpation of the central neck is also critical because this may identify metastatic nodal disease missed during preoperative ultrasound scanning. When transected, the RLN should be reconstructed by primary anastomosis of its uninvolved ends to minimize ipsilateral laryngeal muscle atrophy. An ansa cervicalis nerve graft may be used for this purpose if the RLN cannot be primarily reconstructed in a tension-free manner. Complete initial disease resection also minimizes risk of local/regional cervical recurrence, which often requires reoperative surgery. Reoperative neck surgery is often technically challenging because wound bed scarring after the index operation may obliterate local tissue planes and distort normal anatomic organization. Risk of injury to associated structures, including the ipsilateral RLN and parathyroid glands, is thus higher in reoperative cases.

As is the case for all thyroid surgery, meticulous intraoperative hemostasis must be maintained because even low-volume postoperative bleeding may produce life-threatening airway compromise, requiring emergency evacuation. Intraoperative hemostatic control may be facilitated by use of commercially available vessel sealing energy devices, in addition to traditional electrocautery, suture ties, and titanium clips. Identification of the ipsilateral RLN is required during thyroid surgery and, although nerve identification and functional assessment may be facilitated by use of nerve-monitoring technology, this technology is not a surrogate for manual nerve exposure and dissection. Nonetheless, intraoperative nerve monitor signal loss from an otherwise intact RLN indicates nerve dysfunction and may prompt deferment of planned contralateral thyroid lobe resection. Contralateral RLN injury in this context results in bilateral vocal cord paralysis, with possible associated airway compromise. Last, the thyroid surface should be carefully scrutinized during dissection for adherent parathyroid glands, and, assuming no direct tumor involvement, such glands should be carefully mobilized away from the thyroid, with their native blood supplies preserved. Inadvertent intraoperative devascularization or resection of all four parathyroid glands will produce permanent hypoparathyroidism, with significant morbidity stemming from resultant hypocalcemia. Even when the parathyroid glands are carefully preserved, temporary postoperative hypocalcemia is common, and liberal calcium supplementation may be required temporarily in the immediate postoperative period after total thyroidectomy. Devascularized parathyroid glands should be autotransplanted, most commonly into the ipsilateral sternocleidomastoid muscle.

Thyroidectomy can be classified based on the extent of surgical removal of thyroid tissue. Partial thyroidectomy is the removal of a neoplasm with a large margin of normal thyroid tissue, whereas thyroid lumpectomy is the removal of a neoplasm alone with minimal surrounding thyroid tissue. Subtotal thyroidectomy is defined as the bilateral removal of more than 50% of each lobe, including the isthmus. Hemithyroidectomy or lobectomy is total removal of one lobe of the thyroid with the isthmus. Near total thyroidectomy is the total extracapsular removal of one lobe and isthmus, with 90% removal of the contralateral lobe, such that 1 g of thyroid tissue remains.

Prophylactic Thyroidectomy in MEN2

The ability to identify individuals at high-risk of developing hereditary MTC through germlineRET mutation testing provides a window of opportunity to undertake preventative or curative surgery in otherwise asymptomatic individuals.3,239,268 Indeed, “prophylactic” thyroidectomy has become the mainstay of treatment for children at risk of hereditary MTC, and when undertaken at a sufficiently early stage, it has the potential to avoid the morbidity and mortality associated with MTC development.3,239,250–252,268,282,283 For example, in 2005, a study reported that prophylactic thyroidectomy in 50 patients who were younger than 19 years of age with MEN2-associatedRET mutations resulted in no evidence of residual or recurrent disease in approximately 90% of cases at a mean follow-up period of 7 years. More recently, a study reporting the outcomes of prophylactic thyroidectomy in 167 children with MEN2- and MEN3-associatedRET mutations reported no instances of recurrent or residual disease after a mean of 7 years in any of the 149 patients for whom follow-up data were available. In addition, normalization of postoperative serum calcitonin was observed in 99% of patients who hadraised preoperative calcitonin levels.251 However, it is important to note that the aim of such preventative surgery is not necessarily to remove the thyroid before any abnormality develops but rather to do so before there is a significant risk of metastatic disease. In this regard, the advent of highly sensitive serum calcitonin assays now provides additional information that may help inform surgical decisions, although it should be noted that serum calcitonin concentrations in young children, and especially in the first few months of life, are frequently high and do not accurately reflect disease status. Thus, although prior recommendations on the timing of prophylactic thyroidectomy were based on the risk category of theRET mutation alone,2 more recent guidelines suggest that in some instances it is reasonable to take into account basal or stimulated serum calcitonin levels, which provide a reliable indicator of MTC status and disease risk.3 This represents an important change and recognizes that there remains considerable heterogeneity in the age of MTC onset in those carrying the sameRET mutation who may be even from the same kindred. Furthermore, it suggests that although the risk category ofRET mutation is the major determinant of the age of onset of CCH and subsequent transformation to MTC, additional genetic and/or environmental factors may influence disease expression.

Thyroidectomy in early childhood is associated with a higher complication rate than that observed in older children or adults. Such surgery should only be undertaken at a center with appropriate experience. Complications associated with surgery include a higher likelihood of developing hypoparathyroidism, as frequently the parathyroid glands are hard to identify in very young children. Complications in early childhood are also increased if central lymph node dissection is performed, and this includes the higher risks of transient and permanent hypoparathyroidism, as well as the likelihood of transient recurrent laryngeal nerve palsy.268,284 As a consequence, the timing of prophylactic surgery aims to strike an important balance between the risks associated with early surgery and those associated with more extensive surgical procedures, which may be necessary when intervention is delayed. Current guidelines attempt to address this balance, offering some flexibility in the timing of prophylactic thyroidectomy in children with germlineRET mutations associated with a later age of MTC onset while recommending early surgery in those deemed to be at highest risk (seeTable 42.4). Thus, children identified to harbor the ATA highest-riskRET mutations (i.e., Met918Thr) are recommended to undergo total thyroidectomy in the first year of life, and the higher potential complication rate of hypoparathyroidism in this age group is considered acceptable given the potential for metastatic disease by delaying treatment. In children with ATA high-risk mutations (i.e., codon Cys634 and Ala883Phe mutations), prophylactic thyroidectomy is typically recommended before 5 years of age, with the exact timing based on annual clinical examination, neck ultrasound, and serum calcitonin levels starting from the age of 3 years. For those children with ATA moderate-riskRET mutations, the timing of prophylactic thyroidectomy should be based on the findings of clinical examination, neck ultrasound, and serum calcitonin concentrations commencing at age 5 years.3 Thyroidectomy is indicated once serum calcitonin concentrations are elevated, although it may also be appropriate in children with normal calcitonin levels in whom such long-term monitoring is not feasible or desired. The window of “safe” serum calcitonin concentrations in which curative surgery is feasible has not been precisely defined, although once basal serum calcitonin levels exceed the upper end of the normal range (e.g., ∼10 pg/mL), this may herald the early stages of MTC development and a suitable time for surgical intervention. Serum calcitonin concentrations between 10 and 30 pg/mL may represent an optimal window for intervention, as nodal metastases were not observed to occur in children withRET mutations who had serum calcitonin concentrations of 30 pg/mL or less.268,283 Once calcitonin levels are greater than 30 pg/mL, the likelihood of nodal metastases increases, and this will often necessitate central node dissection, which is associated with increased operative morbidity and a reduction in duration of long-term remission.268,285

POSTOPERATIVE MANAGEMENT

Postoperative care is best undertaken by nurses experienced with thyroidectomy patients because of the potential for airway problems. The Hemovac drains are attached to wall suction and are removed when drainage has stopped, typically within 24 hours. Perioperative antibiotics are not required in these cases because of the very low incidence of wound infection. In patients who have undergone lobectomy, calcium and phosphorus levels are not routinely determined postoperatively unless the patient is symptomatic or has previously undergone thyroid lobectomy. After total thyroidectomy, calcium and phosphorus levels are determined on the second postoperative day. Patients with symptomatic hypocalcemia are treated with calcium. Patients are quickly advanced to a regular diet, are ambulatory on the evening of surgery, and are usually discharged on the first postoperative day. In some centers there is a distinct trend away from draining the wound and to discharge the patient the same day.

Alternative Approaches to Thyroidectomy

The techniques detailed above describe conventional thyroidectomy via an open, anterior cervicotomy approach that has become the standard of care worldwide. As techniques have been refined and technologies have improved, various efforts to minimize the cosmetic effect of a visible neck incision have been investigated. From a historical perspective, the most direct and straightforward means to this end was to decrease the length of the standard cervicotomy incision from 6 to 8 cm down to 3 to 4 cm using traditional instruments and 1.5 to 2.5 cm with the aid of endoscopic instruments. A number of variations have been described with differing terminology, includingminimally invasive,video-assisted,videoscopic/endoscopic, andmini-open, all of which have demonstrated reasonable feasibility and safety in carefully selected patients.

In addition, various investigators have described nontraditional techniques that place incisions in hidden places away from the visible part of the neck, with subcutaneous and/or subplatysmal dissection using minimally invasive surgical instruments to the thyroidectomy area of interest. These so-called “remote access” approaches have largely been developed and widely adopted in Asia and have subsequently established a small but growing niche in the United States and Europe. All require the use of either laparoscopic or robotic instruments, and virtually all can be performed using insufflation of a closed space with CO2 gas or with a gasless technique using custom long tunneled retractors.

There are several different remote access approaches described in the literature differentiated by where the “hidden” incision is placed; the most common sites are the axilla, nipple-areolar complex or chest, retroauricular area at the hairline (the so-called “facelift” approach), and the oral cavity. The most common approaches in the United States are the axillary and transoral approaches.

Transaxillary thyroidectomy using laparoscopic instruments via three small port incisions was first described in Japan in 2000 but first gained traction in the United States in 2007 based on excellent results from South Korea using a robotic, gasless technique with a single incision in the axilla (Fig. 37.36). The initial American experience was marked by an upsurge of complications, including brachial plexus injury, tracheoesophageal injury, lymph leak, and hematoma, which was exacerbated by a combination of inadequate surgeon training and aggressive marketing by the medical device industry. After issuance of warnings by the U.S. FDA in 2013, the manufacturers of the da Vinci surgical robotic system (Intuitive Surgical, Sunnyvale, CA) withdrew active support for robotic thyroidectomy, which led to an abrupt plateau in the adoption of robotic thyroidectomy cases. Since this initial turbulent experience, robotic transaxillary thyroidectomy has benefited from systematic study and steadier reintroduction in only a handful of more experienced centers. A recent experience of 301 cases in the United States revealed excellent technical feasibility (one conversion to open thyroidectomy) and safety (1.3% permanent RLN injury, 1.1% permanent hypoparathyroidism, 0.3% neck hematoma), with only one patient with an approach-specific complication (arm lymphedema which resolved with conservative management) and no recurrences among the 133 patients who had cancer identified histologically.49

TOTS: Robotic Versus Endoscopic Approaches

Transoral thyroidectomy can be performed safely via a purely endoscopic approach using laparoscopic instruments (i.e., transoral endoscopic thyroidectomy vestibular approach (TOETVA), or with the assistance of robotic technology (TORT). Each camp has its proponents. The advantages and disadvantages of each approach are listed in Box 33.1. The primary difference is that TOETVA can be performed with routine laparoscopic instrumentation that exists in most modern hospitals and is therefore widely accessible. This is in contrast to the additional expense and limited access to robotic technology. The robot’s primary advantage is the use of wristed instrumentation and three-dimensional imaging as opposed to straight arm laparoscopic instruments with a two-dimensional screen. The procedures are identical in scope and capability; however, they use different instrumentation to achieve the desired extent of surgery. Nonetheless, TOETVA has garnered significantly more practitioners with currently > 50 centers worldwide in contrast to TORT, which is primarily practiced in a few centers in South Korea.

3 What are the differences between total, near-total, and subtotal thyroidectomy?

A total thyroidectomy removes all grossly visible thyroid tissue. A near-total thyroidectomy removes all grossly visible thyroid tissue except for a small amount (<1 g) adjacent to where the recurrent laryngeal nerve enters the larynx. A total and near-total thyroidectomy have equivalent oncologic outcomes and are often considered synonymous. A subtotal thyroidectomy leaves more than 1 g of thyroid tissue and is not an appropriate cancer operation. It is used occasionally in patients with benign multinodular goiter or hyperthyroidism in an attempt to leave enough thyroid so that thyroid hormone replacement is not required. However, doing so increases the risk of recurrent disease compared with near-total thyroidectomy

Treatment

•

Prophylactic thyroidectomy performed if familial RET mutation detected

FMTC and MEN 2A perform thyroidectomy at age 5-6

MEN 2B perform thyroidectomy during infancy

Mainstay of MTC treatment complete resection of local and regional disease

Total thyroidectomy with level VI nodal dissection ± superior mediastinal nodes

Node levels II-V resected if positive nodes in lateral neck

Adjuvant radiation therapy

XRT used if extensive soft tissue invasion or extracapsular nodal spread

Chemotherapy and tyrosine kinase inhibitors (limited success)

Radionuclide therapy (I-131 MIBG, Y-90 Dotatoc)

Conclusion

TOETVA should no longer be considered an experimental operation. Its safety profile and efficacy have been proven with limited morbidity, when compared to the standards set by the open thyroidectomy.5 Although widespread adoption of remote access surgery in the United States has been slow due to technical, population, and financial considerations, the endoscopic technique has shown to be a standalone in these respects.20 Operative times and costs are comparable to the gold standard technique and still have more room for improvement. Its increase in popularity can be attributed to the cosmetic results of this “scarless surgery,” all while accomplishing surgical goals. TOETVA is the best minimally invasive scarless approach to the thyroid gland. The endoscopic technique applies all of the principles necessary to make for a good minimally invasive surgery. Highlighted by but not limited to the short distance from the oral incision to the gland, the lack of any postoperative residual cutaneous scarring, and the ability to keep costs down by using conventional equipment.

Deciding between an open thyroidectomy versus a transoral thyroidectomy starts with the surgeon determining whether the patient has “favorable features” or “nonfavorable features” for a transoral procedure. A cosmetically pleasing approach for a disfiguring or dysfunctional pathology is an attractive option for motivated patients. With adverse events and complications being similar, or else no worse than the open approach, the utilization of the transoral procedure will inevitably become more widespread. A large randomized prospective trial is still necessary to definitively compare the risks and benefits of a transoral approach versus an open one. Such a study would also help to delineate long-term morbidity and mortality.

VII. Thyroid Insufficiency

Thyroidectomy remains one method to generate a thyroid insufficiency. It is important to have animals that are age matched for these studies because the thyroid hormones are known to decrease with age. The strain of animal, time of day, and season are also known to modulate thyroid concentrations in the blood (15). Three days following thyroid removal, serum T4 concentrations are reduced approximately 15% in rats (16). Five days after thyroidectomy, serum T3 concentrations are reduced over 50% compared with sham-operated rats. The failure to completely eliminate thyroid hormone concentrations most likely indicates that the thyroid gland is not completely removed. This observation reflects technical difficulties in removing the entire thyroid gland. Although the thyroid can be removed, thyroid hormones can be retained within cells for long periods of time. Thyroid hormones are detectable in a variety of tissues for periods up to 4 months (17). Consideration of tissue levels, in addition to serum concentrations, is important in assessing the extent of thyroid insufficiency. Thyroidectomy is known to modulate numerous other physiologic functions of the body that may or may not contribute to the endpoint being measured. Thyroidectomy lowers blood volume, cardiac output, body temperature, and growth hormone. Each of these secondary complications should be addressed by using the appropriate controls.

To compensate for possible damage to the parathyroid gland during thyroidectomy, animals should be given calcium supplements by providing 1% calcium lactate in the drinking water. Despite adding calcium lactate to the drinking water, the plasma calcium concentration remains depressed (18).

In addition to surgical ablation, administration of 131I affords a relatively simple and effective means of destroying the thyroid gland. It can produce the same effects as surgical removal of the thyroid.