Midpoint transverse process to pleura block for postoperative analgesia following laparoscopic renal cyst decortication: Two case reports

Abstract

BACKGROUND

The midpoint transverse process to pleura (MTP) block, a novel technique for thoracic paravertebral block (TPVB), was first employed in laparoscopic renal cyst decortication.

CASE SUMMARY

Thoracic paravertebral nerve block is frequently employed for perioperative analgesia during laparoscopic cyst decortication. To address safety concerns associated with TPVBs, we administered MTP blocks in two patients prior to administering general anesthesia for laparoscopic cyst decortication. The MTP block was performed at the T9 level under ultrasound guidance, with 20 mL of 0.5% ropivacaine injected. Reduced sensation to cold and pinprick was observed from the T8 to T11 dermatome levels. Immediately postoperative Numeric Pain Rating Scale scores were 0/10 at rest and on movement, with none exceeding a mean 24 h numeric rating scale > 3.

CONCLUSION

MTP block was effective technique for providing postoperative analgesia for patients undergoing laparoscopic renal cyst decortication.

Key Words: Midpoint transverse process to pleura block; Laparoscopic renal cyst decortication; Pain; Analgesia; Case report

Core Tip: In this study, we successfully implemented midpoint transverse process to pleura (MTP) block for postoperative analgesia in two patients undergoing laparoscopic renal cyst decortication. The MTP block was performed at the T9 level under ultrasound guidance, with 20 mL of 0.5% ropivacaine injected. Reduced sensation to cold and pinprick was observed from the T8 to T11 dermatome levels. Immediately postoperative Numeric Pain Rating Scale scores were 0/10 at rest and on movement, with none exceeding a mean 24 h numeric rating scale > 3. In summary, MTP block was effective technique for providing postoperative analgesia for patients undergoing laparoscopic renal cyst decortication.

INTRODUCTION

Laparoscopic renal cyst decortication is a minimally invasive procedure that is used to treat symptomatic kidney cysts[1]. While this surgical technique has several advantages, such as smaller incisions and faster recovery time, compared to traditional open surgeries, patients may still experience postoperative pain[2]. Therefore, it is imperative to implement appropriate pain management strategies to effectively alleviate patients' postoperative pain and optimize their overall recovery experience.

In 2017, Costache et al[3] introduced the midpoint transverse process to pleura (MTP) block as a novel thoracic paravertebral block (TPVB) technique. The MTP block involves injecting at the midpoint between the transverse process and the pleura, eliminating the need to identify superior costo-transverse ligament (SCTL), while ensuring a greater distance from the pleura compared to traditional thoracic paravertebral blockade. The MTP block was initially employed in breast surgery[3,4]. MTP block is effective in reducing chest and back pain, making it a suitable option for managing rib fractures and providing thoracoscopic analgesia[5,6]. By utilizing MTP block, anaesthesiologists can effectively target and block specific nerve pathways involved in transmitting pain signals from the surgical site. Abdelbaser et al[7] implemented MTP blocks in pediatric patients who underwent cardiac surgery, resulting in decreased average fentanyl usage during the initial 24 h after surgery, reduced intraoperative fentanyl needs, lower pain scores at rest, and faster extubation times. Nevertheless, there is a lack of existing literature on the application of MTP block as a method for managing postoperative pain following laparoscopic renal cyst decortication. In this study, we present the feasibility and efficacy of MTP block for postoperative pain management in patients who undergo laparoscopic renal cyst decortication.

CASE PRESENTATION

Chief complaints

Case 1: A 74-year-old Chinese man presented to the clinic with episode of gross hematuria for 3 years and recurred symptoms for 1 d.

Case 2: A 44-year-old male patient of Chinese man was diagnosed with a right renal cyst that had been present for two months.

History of present illness

Case 1: The patient had episode of gross hematuria for 3 years, the symptoms of which had recurred in the 1 d prior to admission. The symptoms were characterized by pale red urine with dark red blood clots, while pyuria, dysuria, frequency, and urgency were notably absent.

Case 2: The patient reported that a right kidney cyst was found by ultrasound (US) examination in another hospital 2 months ago. Occasionally, there was intermittent swelling in the right flank region, while lumbago, hematuria, frequency, and urgency were notably absent.

History of past illness

Case 1: The patient has been diagnosed with hypertension for more than 10 years. Oral nifedipine is used to control the symptoms. The patient has been diagnosed with bilateral cataracts for more than 1 year.

Case 2: The patient has a history of being a carrier of the hepatitis B virus, although specific details remain undisclosed.

Personal and family history

The two patients did not have any pertinent familial history of cancer or chronic illness.

Physical examination

Physical examination in two patients revealed no tenderness in the bilateral rib angles and ureter regions, and no tenderness on percussion in the bilateral renal regions. In addition, there were no bladder fullness, deep tenderness, or rebound pain.

Laboratory examinations

Case 1: The blood routine analysis showed a white blood cell count of 7.00 × 10⁹/L and hemoglobin concentration of 147 g/L. The routine urine analysis indicated leucocyte presence at level -, and urine latent blood presence at level 1+. The urine culture result confirmed the presence of no bacterial growth in the sample.

Case 2: The laboratory analysis of the patient yielded no discernible abnormalities.

Imaging examinations

Case 1: Ultrasonography revealed a slightly enlarged right kidney with aberrant morphology, and multiple cystic masses measuring up to 84 mm × 56 mm × 42 mm were identified within the renal parenchyma with Cystic mass with thin smooth wall, clear boundary, good internal sound permeability, enhanced posterior echo, no obvious blood flow signal inside.

Case 2: Ultrasound revealed that the right kidney exhibits normal dimensions and morphology, and a cyst in the central parenchyma of the right kidney. The cyst was approximately 69 mm × 62 mm × 37 mm in size with Cystic mass with thin smooth wall, clear boundary, good internal sound permeability, enhanced posterior echo, no obvious blood flow signal inside.

FINAL DIAGNOSIS

Postoperative pathology in two patients confirmed that the final diagnosis were simple renal cysts.

TREATMENT

Case 1: The patient underwent standard monitoring upon arrival in the operating room. After establishing venous access, sedation was achieved using 1 mg of midazolam and 5 μg of intravenous sufentanil. The patient was instructed to maintain the right lateral decubitus position throughout the procedure. The thoracic spinous processes from T1 to T9 were carefully palpated and subsequently marked. MTP block was initiated between the right T9-10 segments under the guidance of a 6 to 13 MHz linear US probe (Mindray, Te7, Guangdong, China). The needle (80 mm 20-gauge block needle KDL, Wenzhou, Zhejiang Province, China) tip was accurately positioned at the midpoint between the transverse process and pleura, and a precise injection of 20 mL of 0.5% ropivacaine was administered at T9-10. Local anaesthetic spread was observed using US during the injection. We observed consistent downwards displacement of the pleura, without detected increase in the erector spinae plane (ESP) at the T9-10 level (Figure 1). Sensory evaluation was conducted at 5-min intervals using a chilled swab and a blunt 22 G needle tip along the posterior scapular line, the mid-axillary line, and the mid-clavicular line. A decrease in the sensation of the T8-T11 dermatomes was observed 20 min after the initiation of MTP block. Anaesthesia was subsequently induced using 160 mg of propofol, 40 μg of sufentanil, and 80 mg of rocuronium. The combination of propofol and remifentanil was administered to achieve sedation and analgesia during intubation under general anaesthesia (GA).

Figure 1 Ultrasound image of mid-point transverse process to pleura block at the level of the T9 transverse process. ESM: Erector spinae muscle; LA: Local anaesthetic; TP: Transverse process; SCTL: Superior costo-transverse ligament.

Patients underwent traditional three-port laparoscopic renal cyst decortication treatment. After endotracheal intubation under general anesthesia, the patient was positioned in a 90° left lateral decubitus position on the left side. The 10-mm camera port incision, measuring 2 cm in length, was positioned 2 cm above the iliac crest along the midaxillary line. The pneumoperitoneum was obtained using the open technique and, two standard 5-mm operating ports were created 2 cm below the rib margin along the posterior axillary line and 2 cm below the anterior axillary line at rib level twelve respectively. Under laparoscopic guidance, the renal perirenal fascia and adipose capsule were dissected using an ultrasonic knife until adequate excision of the cyst walls was achieved. Following confirmation of no active bleeding, intraperitoneal drainage tube placement was performed through retroperitoneum via trocars. The trocar incisions were then disinfected with alcohol swabs and closed in layers using sutures.

The surgical procedure lasted for a duration of 123 min, during which general anesthesia was administered for a period of 158 min. Propofol was utilized at a dosage of 970 mg, in conjunction with remifentanil at a dose of 2.1 mg throughout the operation. As preemptive analgesia, sufentanil was administered 5 min prior to the conclusion of the surgery at a dose of 5 µg. Following completion of the surgical intervention, patients were transferred to the postanesthesia care unit (PACU) for postoperative recovery.

Case 2: The patients underwent preoperative MTP block prior to undergoing traditional three-hole laparoscopic renal cyst decortication treatment. The planned multimodal analgesia regimen included a 9-level MTP block and GA. MTP block was performed under US guidance, and the distance between the location of the block and the posterior margin of the transverse process was determined to be 0.5 cm. Following the injection of 20 mL of 0.5% ropivacaine, pleural displacement was observed and subtle elevation of the ESP (Figure 2). 20 min after initiating MTP block, the sensorial block was evaluated using the cold and pinprick test. The sensory level decreased from T8 to T11.

Figure 2 Ultrasound image of mid-point transverse process to pleura block at the level of the T9 transverse process. ESM: Erector spinae muscle; LA: Local anaesthetic; TP: Transverse process; SCTL: Superior costo-transverse ligament.

The surgical procedure had a duration of 80 min, during which GA was consistently administered for 120 min. Propofol was employed at an exact dosage amounting to 766 mg, concurrently with remifentanil dosed at 1.4 mg throughout the entire operative process. As part of preemptive analgesia protocol, sufentanil administration took place 5 min before concluding the surgery using an exact dose measurement equivalent to 5 μg. The patient regained consciousness promptly, and 6 min following the successful completion of the surgical procedure, tracheal extubation was performed in the operating room, after which the patient was subsequently transferred to the PACU.

OUTCOME AND FOLLOW-UP

Case 1: After the patient regained consciousness, we removed the endotracheal tube. After tracheal extubation, we refrained from examining the anesthetic area due to the patient's persistent lack of complete consciousness. The numerical rating scale (NRS) score was 0 out of 10 1 h after awakening and 6 h after the operation. 12 h after surgery, the NRS score was recorded as 1/10. However, the patient reported a pain score of 2 during periods of inactivity and 3 during periods of activity on the day following surgery. Notably, no additional analgesic intervention was required during the postoperative period. On the second day after surgery, the patient resumed normal activities, the drainage tube was removed on the third day and was discharged on the fourth day.

Case 2: The NRS score was 0 out of 10 at 1 h post-awakening and 6 h post-operation. The patient was pain free and generally comfortable during the postoperative period. Subsequently, the drainage tube was removed on the third day, and the patient resumed a normal oral diet. Consequently, the patient was discharged from the hospital on the fifth day.

DISCUSSION

Renal cysts are prevalent benign renal lesions. Small cysts typically present no symptoms, while larger cysts can compress the renal parenchyma and cause low back pain or compress the collecting system and lead to hydronephrosis, necessitating surgical intervention[1]. Renal cysts can be treated through various methods, including open surgery, puncture therapy, and laparoscopic surgery. With the widespread adoption of laparoscopic technology, laparoscopic decortication has emerged as the preferred choice for treating renal cysts. Laparoscopic surgery requires a minimum of three incisions measuring 1-2 cm, and the placement of the incisions and drainage tubes elicits pain in patients during and after surgery.

MTP block is a new alternative to paravertebral block[3]. MTP block has been found to provide perioperative analgesia in breast[4,8-11], thoracoscopic[6,12-14], rib[5,15], and spinal surgery patients[16]. Due to the adjacency of the MTP block site with the beginning of nerve branches, the paravertebral spaces in each segment remain open, allowing drugs injected into this space to effectively block the corresponding level's paravertebral nerve and diffuse into adjacent thoracic paravertebral nerves and epidural space when a large volume is administered. Considering that the lower pleural boundary is located at the 12th thoracic vertebra[17], it suggests that MTP block application could also be considered for epigastric and lumbar surgery[18].

In the present study, the two operating ports, positioned 2 cm below the inferior border of the 12^th rib, correspond to the T10 blocked areas. The camera port incision, positioned 2 cm above the iliac crest along the midaxillary line, corresponds to the T11 blocked areas. We observed that using 20 mL of 5% ropivacaine for segmental MTP block anesthesia at the T9 level effectively blocks sensation from the T8-T11 nerve segments and alleviates pain at the laparoscopic incision.

Moreover, MTP block reduces the incidence of accidental injury. For US-guided MTP block, the site selected for puncture is between the two transverse processes and the pleura[3], ensuring that it remains lateral to the SCTL to prevent inadvertent puncture into the pleural or paraspinal space (Figure 3). Conversely, for US-guided TPVB, the aim is to accurately penetrate the SCTL and inject the drug within the paravertebral space. Potentially associated complications include inadvertent vascular puncture, pleural puncture, pneumothorax, and unintentional epidural or intrathecal spread.

Figure 3 Sonoanatomy of the mid-point transverse process to pleura block. ESM: Erector spinae muscle; TP: Transverse process; MTP: Midpoint transverse process to pleura; PVS: Paravertebral space.

The use of MTP block for postoperative analgesia has shown promising results in clinical studies. Patients who have undergone laparoscopic renal cyst decortication report a decrease in pain intensity and an improvement in postoperative recovery when this technique is utilized.

To the best of our knowledge, this is the first case report documenting the effectiveness of MTP block in laparoscopic renal cyst decortication. Future larger randomized studies are required to further demonstrate and validate the efficacy of MTP block in patients undergoing laparoscopic renal cyst decortication.

CONCLUSION

In this study, we successfully implemented MTP block for postoperative analgesia in two patients undergoing laparoscopic renal cyst decortication. The MTP block was performed at the T9 level under US guidance, with 20 mL of 0.5% ropivacaine injected. Reduced sensation to cold and pinprick was observed from the T8 to T11 dermatome levels. Immediately postoperative Numeric Pain Rating Scale (NRS) scores were 0/10 at rest and on movement, with none exceeding a mean 24 h NRS > 3. In summary, MTP block was effective technique for providing postoperative analgesia for patients undergoing laparoscopic renal cyst decortication.