Bleeding is one of the most common surgical complications of herniated lumbar disc surgeries(2). The blood loss under the endoscope during PELD is generally less than 10 ml, but there also can be massive bleeding. A large amount of bleeding may result in an unclear view, lengthen the time of operation, increase the frequency of radiographic examination, and make postoperative VAS and ODI scores higher. Thus, evaluating the endoscopic blood loss accurately is very important to evaluating the curative effects of surgery, as well as for clinical studies. Currently, the empirical approach is the most popular approach used in clinical practice. However, the approach is convenient but not accurate. Estimation of the endoscopic blood loss in the same operation can vary widely from surgeon to surgeon. The HCT-M and RBC-M are two new methods we devised to estimate endoscopic blood loss in PELD.
The clinical study showed that the volume of 0.9% saline used for flushing tissues varied from 2.00 l to 8.00 l and the diluted times of rinse solution varied from126 times to 470 times, So the endoscopic blood loss in PELD can be calculated out by HCT-M according to the results of the in-vitro experiment. Compared with the EMP-M, HCT-M is more sensitive, more accurate and more reliable. Besides, the clinical research also found that the amount of endoscopic blood loss affects the operative procedure in operation time and fluoroscopy frequency, as well as clinical effects in VAS and ODI scores after operation in the short-term.
To understand the causes of bleeding and grasp the hemostatic measures are necessary skills for the operation of PELD. The main causes of intraoperative bleeding were analyzed as follows: (1) surgical operation injured the internal and external blood vessels of the spinal canal; (2) patients’ coagulation function was decreased; (3) anatomical factors of vertebral vein system: the venous plexus in the spinal canal, which is wrapping around the dural sac, is divided into the anterior plexus and the posterior plexus; (4) the intervertebral foramen vein is always accompanied by the nerve root, and the venous plexus in the spinal canal is connected with the celiac venous plexus(21); (5) surgeon’s experience is also an important factor according to the learning curve of PELD(22, 23).
There are several measures to stop bleeding under the endoscope (Fig. 4). First, satisfactory hemostatic effects can be obtained with hemostatic agents preoperatively or intraoperatively, such as batroxobin, tranexamic acid, reptilase, and aprotinin(24–26). Second, taking advantage of bipolar radio frequency (RF) heat coagulation is also a useful way to stop bleeding(27, 28). Venous plexus hemorrhage in the spinal canal and intervertebral foramen can be stopped by bipolar RF cautery. A collapsible Elliquen bipolar RF scalpel was used during PELD, and this tool can stop the bleeding of most vessels in the spinal canal, as well as remove the granulation tissue and new blood vessels in the ruptured annulus fibrosus. Hemostasis can be realized through low temperature vaporization mode and high temperature coagulation mode. In the high temperature mode, the bipolar RF scalpel must keep away from the nerve root; but sometimes deep bleeding will suddenly obscure the field of vision, leading to an inability to distinguish the bleeding point clearly. In this situation, the high temperature mode is dangerous and the low temperature mode is useless. Thus, some other measure must be taken to stop the bleeding.
Working cannula compression is another useful way to stop bleeding. By compressing the bleeding point with the working cannula and waiting for some minutes, the bleeding will stop. In the meantime, the surgeon can turn the field of vision to the non-bleeding area, removing the nucleus pulposus and other tissues in the non-bleeding area first. However, sometimes the bleeding cannot be stopped, and the surrounding bleeding will flow into the working cannula. Another method is to increase the pressure of water in the spinal canal to form an area of high pressure outside the epidural. This method can be used for a small amount of errhysis and can decrease the time to replace the instrument. However, the time of high pressure outside the epidural should not be too long, or it will lead to intracranial hypertension, and various kinds of adverse reactions will occur (e.g., dizziness, headache, nausea and vomiting, blurred vision, tinnitus, and increased blood pressure).
Apart from the aforementioned methods, filling a gelatin sponge (29, 30)or hemostatic gauze is also frequently used to stop bleeding. When other methods are unable to stop bleeding, place a gelatin sponge or hemostatic gauze in the bleeding area and gently compress it with nucleus pulposus forceps. Generally, the bleeding can be stopped in approximately 2 min. Next, take out the foreign substances to reduce the chances of adhesion and infection in the spinal canal. Last but not the least, place a drainage tube. Some patients’ coagulation function is very poor due to the long-term use of painkillers and non-steroidal anti-inflammatory drugs (NSAIDS). These drugs affect the aggregation of platelets, increasing intraoperative bleeding during and postoperative errhysis of PELD. A drainage tube must be put in a vertebral canal hemorrhage area and connected to the negative pressure drainage ball. The tube is pulled out when the drainage fluid is less than 5 ml in 24 h after the operation. There are also some other measures can be taken to stop the bleeding such as spraying cold saline or hemostatic agent locally(31). In summary, surgeons should use these kinds of hemostasis flexibly according to the actual situation of operation and their personal experience.
In summary, this study based on practical problems encountered during PELD, came up with two new methods to estimate endoscopic blood loss, tested the theory through an in-vitro experiment and then came back to clinical research to confirm the results, analyze the causes of bleeding and summarize hemostatic measures. Although the study only enrolled 74 patients with L5/S1 disc herniation and the operation method were limited to transforaminal approach, but no matter which segment of LDH and whether the posterior approach or the lateral posterior approach, the method to estimate endoscopic blood loss, the cause of bleeding and the hemostasis are the same. So, this study can be a guideline for surgeon in PELD and all the patients with LDH can benefit from the research. The study also has limitations, bipolar RF heat coagulation may destroy some RBCs in stopping the bleeding. Although the impact is small, it may affect the results of laboratory examination.