Pathophysiology of airway obstruction caused by wound hematoma after thyroidectomy: an ex vivo study

Evaluation of Hematoma Formation after Thyroidectomy Surgery and Its Related Factors

Background

In the last decade, the number of patients undergoing thyroidectomy has increased. Compared to other methods, thyroidectomy is a relatively safe method for treating various types of thyroid diseases. However, the blood flow rate in the thyroid gland is high, and hematoma after thyroidectomy is one of its complications. We aimed to evaluate hematoma after thyroidectomy and its related factors.

Methods

In this retrospective study, 2320 patients over 20 years of age who underwent thyroidectomy in Imam Khomeini, Arvand, and Mehr Ahvaz hospitals, Khuzestan Province, southern Iran between 2011 and 2022 were enrolled. Data were analyzed using SPSS software, version 22.

Results

70.7% of the patients were in the age range of 20-50 years. Twenty-five (1.1%) of patients developed a hematoma after thyroidectomy. Males are more likely to hematoma after surgery (P=0.01). Hematoma was significantly higher in patients with a history of hypertension (P=0.001). Moreover, a significant association was found between male gender, and age over 50 years with the risk of hematoma (P<0.05). The incidence of hematoma had a statistically remarkable correlation with follicular thyroid cancer pathology (P=0.001). Other pathology diagnoses were not significantly related to hematoma formation after thyroidectomy.

Conclusions

Hematoma after thyroidectomy surgery is a rare, but dangerous and life-threatening complication. It is important to identify risk factors for hematoma formation.

Efficacy of four different hemostatic agents in thyroid surgery in reducing the amount of post-operative fluid collection

PURPOSES

Postoperative bleeding remains a life-threatening complication in thyroid surgery. The aim was to assess the efficacy of four different hemostatic agents, Collagen-Fibrinogen-Thrombin Patch (CFTP) in two sizes (3 × 2.5 cm and 9.5 × 4.8 cm), polysaccharide particles (1 g) and Cellulose Gauze (2.5 × 5 cm) on postoperative drainage volume (DV) compared to a control group.

METHODS

We included from October 2007 until Mai 2011, 150 patients (30 per group) for this monocentric, retrospective case-controlled study. Patients were scheduled for a hemithyroidectomy or thyroidectomy. The primary endpoint was the postoperative DV within the first 24 h, secondary the incidence of adverse events.

RESULTS

There were no difference in demographic parameters. The mean DV (± SD) was 51.15 (± 36.86) ml in the control, 50.65 (± 42.79) ml in small (3 × 2.5 cm), 25.38 (± 23.99) ml in large CFTP (9.5 × 4.8 cm), 53.11 (± 39.48) ml in the polysaccharide particles and 48.94 (± 30.59) ml in the cellulose gauze group. DV was significantly reduced with the large CFTP (p < 0.05) compared to all other groups. There were no adverse events.

CONCLUSIONS

We were able to demonstrate a significant reduction in the DV for the large CFTP group compared to the other collectives. Although this as being associated with not inconsiderable costs and we would only recommend its use for high-risk patients only.

A cervical compartment syndrome impairs cerebral circulation in post-thyroidectomy hemorrhage: data from an animal model

BACKGROUND

Post thyroidectomy hemorrhage is a potentially life-threatening complication. As the mechanism leading to hypoxemic brain damage and death is still unknown, our aim was to examine the underlaying pathophysiology in an animal model.

METHODS

A series of experiments was performed in our established model for post thyroidectomy hemorrhage in 6 pigs. First, post thyroidectomy hemorrhage was simulated with an artificial increase of cervical compartment pressure. Second, spontaneous bleeding into the cervical compartment was initiated. Primary outcome measure is the correlation between cerebral oxygenation and cervical compartment pressure.

RESULTS

With an increase in cervical compartment pressure apnea could be detected in all experiments. A significant 24.2% (9.5-34.4%) decrease of cerebral oxygenation at time of apnea (47.0%; 38.0-65.0%) compared to baseline values (63.5%; 56.0-74.0%; P=0.043) occurred due increase of cervical compartment pressure concurrent with an impaired cerebral perfusion. Apnea occurred about 200 sec after a 10% decrease of cerebral oxygenation, but 35 sec before a 10% decrease of peripheral oxygenation. Spontaneous bleeding into the cervical compartment causes an increase of cervical compartment pressure reaching levels of the mean arterial blood pressure 56.0 (35.0-72.0) mmHg.

CONCLUSIONS

Peripheral hypoxemia occurs with relevant delay in time after decrease of cerebral perfusion and cerebral hypoxemia, therefore cerebral hypoxemia seems to be causal for a central apnea. With this evidence of impaired cerebral perfusion and cerebral hypoxemia due to an increased cervical compartment pressure we can disprove the historic theory of tracheal collapse due to a compressive hematoma in post thyroidectomy hemorrhage. A cervical compartment syndrome seems to be causal, not only for brain hypoxemia but also an additional laryngo-pharyngeal mucosal edema.

New insights into the pathophysiology of postoperative hemorrhage in thyroid surgery: An experimental study in a porcine model

BACKGROUND

Postoperative cervical hemorrhage is a rare but life-threatening complication that can cause severe morbidity. Different mechanisms leading to asphyxia have been described based only on clinical observation.

METHODS

We performed a series of in vivo animal studies simulating post-thyroidectomy hemorrhage and its effect on respiratory drive. Three series of tests were carried out in 12 German domestic pigs under general anesthesia. The pigs were breathing spontaneously with secured airways. An additional series using functional magnetic resonance imaging of the pigs' brainstem was also conducted.

RESULTS

The first experimental series carried out on 2 animals revealed an obvious difference between the effects of cervical hemorrhage and external bleeding with development of hemorrhagic shock. An experimental setting for the repeated simulation of cervical hemorrhage was established. A pressure-dependent mechanism was discovered that led to apnea in every animal despite the secured airway. In 8 of 10 animals, relief of cervical pressure led to complete respiratory recovery. The test was repeated up to 6 times per pig. Apnea was induced in 25 of 25 test procedures (100%) and was followed by respiratory recovery in 22 of 25 tests (88%). The threshold pressure at which the respiratory rate started to decrease was 47 ± 14 Torr when blood was used to increase the cervical compartment pressure. When silicone oil was used in a further experimental series, the threshold pressure was similar at 44 ± 21 Torr. The cervical compartment pressure needed to induce apnea was 74 ± 18 Torr using blood and 74 ± 39 Torr using silicone oil, both of which exceeded the mean arterial pressure by 28 Torr during apnea. Functional magnetic resonance imaging revealed a decrease in brainstem activity during phases of increased cervical compartment pressure, which suggests a possible role for cerebral vascular perfusion.

CONCLUSION

Respiratory drive can be suppressed by increased pressure in the cervical compartment, possibly because of a pressure-dependent impairment in cerebral perfusion through a form of cervical compartment phenomenon or, less likely, a pressure-dependent reflex (nervous) mechanism.

Compartment Pressure Monitoring After Thyroid Surgery: A Possible Method to Detect a Rebleeding

BACKGROUND

Postoperative rebleeding after thyroid surgery is a rare but a serious complication. The aim of this study was to ascertain the extent to which postoperative pressure could be used as detector for rebleeding after thyroid surgery.

METHODS

Thirty-two patients with thyroidectomy or hemithyroidectomy were considered prospectively. In the course of surgery, a pressure microsensor (3PN Probe Spiegelberg) was implanted into the postoperative cavity and data were collected for special activities and stress situations over the first 48 h postoperatively. Additional endpoint was the influence of drains on the determined values.

RESULTS

The overall mean pressure (MP) at rest on both postoperative days for all patients with and without drain was 0.36 ± 2.84 mmHg (range -6.7 to 6.7). The MP in all activity and stress situations on the first day was with 0.23 ± 3.71 mmHg, and on the second day, the MP was 1.33 ± 4.50. 92.13% of our values were below 7 mmHg. One patient had a hemorrhage. The pressure increases continuously up to 36 mmHg, before the patient was transferred to the operating theater.

CONCLUSIONS

This is the first pilot study to consider continuous pressure measurement to be a potential tool for early detection of a postoperative rebleeding in thyroid surgery. In the strictest sense, postoperative intra-cervical pressure at rest ranges from subatmospheric to 7 mmHg. The elevation of pressure in case of a rebleeding up to 36 mmHg differs dramatically from normal postoperative pressure. The collected data will warrant further validation to be able to recommend threshold values for an early treatment decisions in rebleeding.