Exploring Extrapleural Hematoma After Ultrasound-Guided Paravertebral Block: A Clinical Case Report

Introduction

Ultrasound-guided thoracic paravertebral block is a technique that injects the local anesthetics into the paravertebral space, and is widely applied in thoracic surgery because of its effective intraoperative and postoperative analgesia [1]. Traditional thoracic paravertebral block can lead to serious complications [2]. The application of ultrasound Doppler technology has significantly lowered the incidence of complications [3]. However, although the incidence of vascular injury is relatively low [4,5], intercostal arterial damage in severe cases can lead to significant hemorrhage or local hematoma [6,7]: extrapleural hematomas are located in the extrapleural space between the parietal pleura and endothoracic fascia, and intrathoracic hematomas are located in the potential space between the visceral pleura and parietal pleura. Substantial hemorrhaging can result in hypovolemic shock, and large hematomas can exert mechanical compression on adjacent neural tissues, causing neurological dysfunction such as limb numbness, motor impairment, or intensified pain. Extrapleural hematoma results from bleeding between the parietal pleura and the internal thoracic fascia. When using imaging to diagnose extrapleural hematoma, a chest radiograph may demonstrate linear or rounded parietal shadows. A chest CT scan may reveal the “displaced extrapleural fat layer and parietal pleura” sign, which is pathognomonic for extrapleural hematoma [8]. It has been reported that patients with a definitive diagnosis of extrapleural hematoma have recovered without undergoing invasive treatment [9]. Extrapleural hematoma can expand due to tissue laxity, usually caused by intercostal arterial bleeding, and blood transfusion may be required during treatment. For stable patients, the treatment of extrapleural hematoma should be a limited or full thoracotomy. For patients on anticoagulants, the treatment of expanding external hematoma should be the same, but may need to be managed urgently [8]. The aim of this case report is to analyze the possible mechanisms of extrapleural hematoma, discuss the effect of anticoagulation on hematoma, and make recommendations for prevention and treatment.

In this case, to ensure no local anesthetic entered the blood, repeated aspiration was performed during the ultrasound-guided thoracic paravertebral block puncture process. After successful placement of the needle, the local anesthetic was injected and a noticeable downwards displacement of the pleura was observed during the injection. The block was confirmed to be successful by thermal sensation testing. The patient received 2 prophylactic doses of low-molecular-weight heparin (4000 U) after the operation. However, a 4×5 cm local hematoma was found at the T6–T7 paravertebral segment intraoperatively. We speculated that the hematoma may have been associated with an unintentional puncture of an intercostal artery and under the anticoagulant effect of low-molecular-weight heparin. Only 1 similar case of such a huge hematoma has been reported in the literature [4]. Our study examined the underlying causes of this severe bleeding event and explored early treatment strategies to address it. This report describes the case of a 61-year-old man with extrapleural hematoma after ultrasound-guided thoracic paravertebral block following right upper-lobectomy.

Case Report

The patient was a 61-year-old man with a weight of 58 kg and a height of 166 cm. He had a 10-year history of hypertension and had poorly controlled type 2 diabetes. The patient had no history of taking any anticoagulant medication preoperatively, and preoperative coagulation function was normal. Preoperatively, the hemoglobin level was 172 g/L, the platelet count was 168×109/L, and the fasting blood glucose level was 10-13 mmol/L. He underwent a video-assisted right upper-lobectomy. He was given 0.03 mg/kg of midazolam and 10 μg of sufentanil in the preoperative room before undergoing ultrasound-guided thoracic paravertebral block. An ultrasound (Sonosite 3–5 Hz high-frequency linear transducer) was used to guide the in-plane paramedian sagittal approach puncture. At the T3 segment, the high-frequency probe was placed 2.5 cm lateral to the midline area perpendicular to the spine, and the transverse process and pleura were clearly imaged. The puncture needle (22 G) was parallel to the probe and was advanced laterally towards the T3–T4 paravertebral space. During the puncture, the needle was clearly visualized, and intermittent aspiration of the syringe showed no blood return. When the needle tip approached the pleura, normal saline was injected while the needle was slowly advanced, and the needle was stopped after the pleura was displaced downwards (needle depth of 4.5 cm). The syringe was replaced, and after ensuring no blood return, 20 ml of local anesthetic (0.25% ropivacaine, AstraZeneca) was injected. At this time, displacement of the pleura and expansion of the intercostal space were visible under ultrasound. The same method was used to inject 20 ml of local anesthetic at the T6–T7 segment. A thermal sensation test was performed on the blocked area to determine the success of the block. After 15 minutes, the patient was transferred to the operating room. The anesthesia induction was accomplished with 20 μg of sufentanil, 20 mg of lidocaine, 12 mg of cisatracurium, and 12 mg of etomidate. After 5 mins of anesthesia induction, the double-lumen endobronchial was intubated. After successful positioning with a fiberoptic bronchoscope, we prepared to performed the lobectomy. After the thoracoscope was inserted into the chest cavity, a local hematoma of approximately 4×3 cm was found at the T6–T7 paravertebral segment (Figure 1). However, after careful evaluation by the surgical team, it was determined that the hematoma was localized with a small volume and no significant active bleeding. To avoid further damage to the thoracic pleura, the surgeons decided not to cut the hematoma and proceeded with the surgery. Briefly, the surgeons firstly dissected the right upper lobe under assistant of fiberoptic bronchoscope. After anatomical dissection of the right upper lobe, the right upper lobe was resected using a stapler. Systematic mediastinal and hilar lymph node dissection was performed concurrently. Following resection, the surgical team meticulously evaluated the pulmonary staple lines and lymph node dissection margins to ensure hemostasis and integrity. Once no active bleeding or complications were identified, thoracotomy closure was completed. During the operation, the patient’s vital signs were stable. At the end of the operation, the surgeon carefully assessed the hematoma again and decided not to treat it. The patient was transferred to the post-anaesthesia care unit, and then was transferred to ward after extubation.

The patient was followed up for 8 hours after the operation, with normal vital signs and a pain score of approximately 0–1. At postoperative 16 hours, he received a subcutaneous injection of 4000 IU of low-molecular-weight heparin. At this time, he was alert and verbal, with a pain score of approximately 1–2, a hemoglobin level of 152 g/L, and a platelet count of 154×109/L. A follow-up chest X-ray at 22 hours after surgery revealed swelling and air accumulation in the right chest wall. At 40 hours after surgery, he received another subcutaneous injection of low-molecular-weight heparin 4000 IU. At 49 hours after surgery, he suddenly felt severe chest pain, followed by respiratory distress. At this time, blood pressure was 89/50 mmHg, heart rate was 102 bpm, and SpO2 was 83~88%. Approximately 100 ml of brown liquid was found in the drainage tube. The hemoglobin was 75 g/L and the platelet count was 157×109/L (Table 1). These indicators collectively indicated that the patient was in a state of hypovolemic shock. After discussion, an emergency operation was immediately performed. After the thoracoscope was inserted, an extrapleural hematoma extending from T1 to T12 on the right side was found (from the top of the pleura to the diaphragm plane, approximately 10×20 cm in size). After puncture of the pleura, some coagulated blood clots and about 3000 ml of uncoagulated blood were found. After clearing the coagulated and uncoagulated blood in the chest, the surgeons carefully examined the chest wall from the pleural apex to the diaphragm and the lung tissue. No obvious bleeding vessels were found in the lung tissue or chest wall, but there was significant oozing from the surface of the chest wall.

The surgeons performed electrocautery hemostasis on the oozing areas of the chest wall and applied hemostatic gauze on the oozing aeras of chest wall to stop the bleeding, while also using gauze for compression hemostasis. During the process of hemostasis, the plasma, coagulation factors, cryoprecipitate, and prothrombin complex concentrate were also injected to improve the coagulation function. After confirming that there was no obvious oozing from the chest wall, the chest was closed. During surgery, 2500 ml of blood was transfused (including 1000 ml of salvaged autologous blood), and 15 mg of protamine and 1 U of vasopressin were administered intravenously. After the patient woke up and was extubated, he was transferred to the ward for further treatment. On postoperative day 8, his condition improved, and the intrathoracic packing gauze was removed. Figure 2A–2D illustrate the perioperative chest X-ray progression over 1 week. Figure 2A (preoperative) shows normal baseline. Figure 2B (1st day after first the operation) shows a massive right hemothorax with atelectasis and leftward mediastinal shift. Figure 2C (1st after second operation with gauze packing) shows complete opacification (“white-out”) of the right hemithorax due to gauze plus residual blood, increasing the mass effect. Figure 2D (8th day after first operation after gauze removal) shows organized blood reabsorbed, lung fully re-expanded, chest cavity re-aerated, and mediastinum returned to midline, essentially restoring the preoperative appearance. However, 2 hours later, the patient developed hypoxemia requiring transfer to the ICU for escalated respiratory management.

Discussion

We discuss whether anticoagulants should be administered postoperatively when signs of a paravertebral-block-induced local hematoma are identified, how to assess and monitor for progressive active bleeding, and how to manage ongoing hemorrhage. Thoracic paravertebral block is a relative dangerous but effective regional analgesia technique, which inject the local anesthetics into the thoracic paravertebral space. However, some complications, such as pneumothorax, local anesthetic systemic toxicity, and vascular injury, are dangerous for patients. Compared with traditional technique, application of ultrasound technology can provide clear, real-time, dynamic imaging and lower the incidence of complications [10], thereby improve the efficacy and safety of thoracic paravertebral block. However, even with use of ultrasound technology, some complications can still occur [10,11].

Our patient received ultrasound-guided thoracic paravertebral block before surgery, and a local hematoma of approximately 4×5 cm was found at the T6–T7 paravertebral segment during the operation. Based on the evidence, we speculate that the intercostal artery was injured during the puncture procedure, resulting in the formation of a hematoma. This mechanism aligns with findings previously reported by Song et al [6]. Without ultrasound guidance, the probability of vascular injury during paravertebral block is relatively high. It had been reported that nearly 7% of patients have blood aspirated back, and approximately 3% of patients have hematoma at the puncture site [2]. Bleeding occurs between the parietal pleura and the inner thoracic fascia (the extrapleural space), which is called an extrapleural hematoma [12]. There is loose connective tissue between the parietal pleura and the inner thoracic fascia, especially on both sides of the spine, which makes it easy for the parietal pleura and the inner thoracic fascia to be separated by active bleeding to form an extrapleural hematoma [13] when there is injury to the blood vessels of the chest or intercostal vessels combined with coagulopathy. Since the visceral pleura is still intact at this time, the blood in this region cannot drain through the thoracic drainage tube, which can delay the diagnosis of extrapleural hematoma and ultimately lead to severe hypovolemic shock [14]. Similar to previous case reports [9], our patient presented with decreased blood pressure and reduced hemoglobin levels. In clinical work, the early identification of extrapleural hematoma is difficult, but emergency intervention is critical to prevent respiratory failure and circulatory collapse [12]. For the treatment of extrapleural haematoma, when the patient’s vital signs are stable and the hematoma is small, Poyraz et al recommended drug treatment or simple observation; if the haematoma is large and causes circulatory and respiratory disorders or if the patient has unstable vital signs due to active bleeding, thoracotomy for hemostasis is recommended [9,15]. Sumida et al [16] reported a case of a large extrapleural haematoma in a patient receiving anticoagulant therapy for a nontraumatic condition, suggesting that video-assisted thoracic surgery may be the preferred method for treating extrapleural hematoma. In this case, the patient’s coagulation function was normal before surgery, and he had not yet received anticoagulant treatment. The size of the hematoma did not increase over 1 hour of observation, so it was not surgically treated at that time.

Coagulopathy, abnormal bleeding, and anticoagulant therapy are considered contraindications for thoracic paravertebral block [6]. Several studies have reported that video-assisted lobectomy can be associated with serious postoperative complications, such as pulmonary vein thrombosis and cerebral or other organ infarctions [17,18]. To reduce the incidence of these complications, low-molecular-weight heparin (LMWH) is commonly administered postoperatively in clinical practice [19]. Recent clinical trial data indicate that preoperative administration of low-molecular-weight heparin significantly reduces the risk of intraoperative bleeding [20]. Additionally, a study has suggested that a low dose of low-molecular-weight heparin does not worsen coagulation outcomes following lobectomy [21]. Ganguli et al reported a case in which 18 000 IU/d of low-molecular-weight heparin was administered for thromboembolism prevention; 3 days later, the patient’s thoracic drainage volume increased, and the patient was diagnosed with spontaneous hemothorax caused by low-molecular-weight heparin [22]. In our case, 4000 IU of low-molecular-weight heparin was given subcutaneously at 14 hours and 40 hours after surgery, and this dose of LMWH was lower than that used in clinical trials [20,21]. During this process, APTT increased from 30.2 s before surgery to 40.8 s after surgery. Unlike spontaneous hemothorax, in our case, the puncture had already activated the intrinsic and extrinsic coagulation pathways, and low-molecular-weight heparin changed the physiological balance of the coagulation process by inhibiting the activity of factor Xa [23]. Therefore, after the use of low-molecular-weight heparin, the original extrapleural cavity hematoma rapidly developed into a large hematoma.

The mechanism of extrapleural haematoma in our patient was unclear. The extrapleural hematoma might have been caused by the complex of negative pressure in the chest cavity and the coagulation dysfunction. The extrapleural hematoma under direct visual inspection via thoracoscopy separated the parietal pleura from the inner thoracic fascia, and owing to the pressure of the surrounding tissue on the hematoma, there was no progressive development of the hematoma during the observation period. After the operation, spontaneous inhalation required movement of the thoracic cage to provide negative pressure in the chest cavity. At this time, the inner thoracic fascia followed the movement of the thoracic cage; however, the parietal pleura could not move synchronously with the inner thoracic fascia because of the limitation of negative pressure in the chest cavity. Relative displacement occurred between the 2 layers of tissue, and the pressure effect on the hematoma disappeared, causing the hematoma to increase in size. Moreover, the “tearing” of the 2 membrane structures with respiratory movement led to an increase in the wound surface inside the hematoma. Many capillaries in the newly added wound surface ruptured and bled, and the original hematoma quickly developed into an extensive hematoma with the support of new bleeding points. At this time, the patient presented typical symptoms such as respiratory distress, an increased heart rate, decreased blood pressure, and a low hemoglobin level.

Conclusions

After detecting local hematoma or bleeding caused by paravertebral nerve block, use of anticoagulant drugs should be avoided as much as possible after surgery. Moreover, biochemical tests and imaging examinations should be actively used to assess for ongoing bleeding. If the bleeding worsens, surgical intervention should be considered as early as possible.