Hemostasis in Endoscopic Spine Surgery
Article information
Abstract
Bleeding is a commonly encountered problem in spine surgery. The increasing popularity of endoscopic spine surgery poses new challenges to spine surgeons, especially those who are embarking on the learning curve. Hemostasis in endoscopic spine surgery can be difficult due to the narrow working channel and bleeding obscuring the endoscopic view, which hinders hemostasis and effective continuation of the operation. To minimize the risk of bleeding and improve hemostasis, a multimodal approach should be employed, including appropriate strategies for perioperative prevention, intraoperative surgical techniques, and postoperative correction/care. In this technical review article, we discuss several hemostatic techniques that are commonly used in endoscopic spine surgery. We also describe a new bone wax application technique in endoscopic spine surgery—called the “bone wax on pattie” technique—to avoid bone wax sticking onto the working channel/endoscope lens, while enabling easier application of bone wax onto the bleeding bone surface. We share some of our experiences with hemostasis in endoscopic spine surgery, and we hope to gather feedback from fellow spine surgeons around the world, so that we can contribute to further developments in the field together.
INTRODUCTION
The advent of endoscopic spine surgery in recent years has led to further decrease in the invasiveness of spinal surgery. It also brings the potential for more superior clinical outcomes and faster recovery, enabling a quicker return to daily activities compared to traditional open surgery [1]. However, it poses new technical challenges to surgeons, and the benefits can only be fully realized when we thoroughly comprehend the potential complications and employ effective preventive strategies. As with any spinal surgical procedure, unexpected bleeding and resulting hematomas can occur following endoscopic spine surgeries. While the majority of postoperative hematomas may be asymptomatic or subclinical, with the reported need for surgical evacuation as low as 0.1% [2], rare occurrences can still result in devastating clinical conditions such as neurological deterioration [3]. Hemostasis technique is therefore crucial on top of other challenges such as orientation of anatomy under the endoscope, handling of the endoscope, familiarity with the instruments, and drilling techniques. Hemostasis under the endoscope can be especially challenging due to the narrow working channel and even a small amount of bleeding can obscure the surgeon’s view, making it more difficult to identify the bleeding point and to stop the bleeding effectively. Like any other surgeries, to minimize the frequency and severity of bleeding, a multimodal approach should be considered, including preoperative assessment and optimization (consider stopping medications/supplements that can increase intraoperative bleeding risk in patients with high risk of blood loss), intraoperative management such as good anesthetic technique with good blood pressure control, measures to prevent compression on the abdomen, in conjunction with various surgical hemostatic techniques. Thankfully, owing to the minimally invasive approach of endoscopic spine surgeries, which necessitate minimal working space during the procedure, there is restricted opportunity for bleeding or hematoma formation. Consequently, the majority of hematomas that do arise are either asymptomatic or self-limiting in nature. Nevertheless, rigorous efforts are still essential to mitigate the risk of bleeding. In this review article, we aim to share some of our techniques and experiences in achieving meticulous hemostasis during endoscopic spine surgery.
HEMOSTASIS TECHNIQUES
Bleeding in endoscopic spine surgery originates from the usual sources such as skin, adipose tissue, muscle, bone, joint vessels, ligaments, and epidural vessels. Depending on the source of bleeding, different hemostatic techniques should be used to tackle the problem effectively. For example, infiltration of local anesthetic agent with epinephrine provides good hemostasis for skin and subcutaneous tissue, while radiofrequency (RF) probe is good at controlling bleeding from muscles. Like any other surgeries, good and clean dissection of various structures is a very important first step in reducing bleeding during surgery. The endoscope can be rotated to allow enhanced visualization of the surgical field as well as identification of the bleeding points. When there is a suspected bleeding point, the scope should be advanced with the lens being close to the bleeding point to allow careful examination and subsequent hemostasis. Repeated rubbing of endoscopic port against soft tissue, bone or facet joints should be avoided as it will lead to recurrent bleeding. In endoscopic spine surgery, some tolerance of slow oozing of small amount of blood not affecting the surgeon’s visual filed could be allowed. However, once bleeding tolerance is exceeded, immediate hemostasis becomes imperative, as controlling it becomes increasingly more challenging as the surgery progresses without intervention. We discuss several hemostatic techniques that are commonly used in our practice, including a modified technique to apply bone wax under the endoscope.
1. Irrigation
Continuous irrigation is an integral part of endoscopic spine surgery as normal saline serve as the medium intraoperatively. The irrigation pressure should not exceed patient’s diastolic pressure. We use an initial default setting of 40 mmHg and a flow rate of 0.4 L/min in our center [4]. A standard continuous irrigation exerts a constant pressure, providing a gentle yet continuous compressive hemostatic effect throughout the surgery, effectively managing minor bleeding. When there is excessive bleeding, the outflow of the irrigation system can be transiently closed to identify and examine the bleeding point. The irrigation pressure can be temporarily increased to help to reduce bleeding by overcoming the venous pressure, allowing for visualization and cauterization of the bleeding point. Some irrigation pump systems feature programmed transient high-pressure flow actions specifically designed for hemostatic purposes. However, these maneuvers should be used with caution and for the shortest duration possible, due to the risk of increasing intracranial pressure, especially in the setting of dura tear. In our experience, usage of such maneuvers seldom exceeds 5 seconds. As soon as the bleeding focus is identified and controlled, outflow is immediately opened, and irrigation pressure is returned to baseline to minimize pressure-associated complications. If bleeding is not controlled with one attempt, irrigation pressure should be returned to baseline before the next attempt. Alternatively, dual irrigation channels with one channel connected to continuous irrigation, and another channel connected to a syringe which allows intermittent flushing (of small amount of fluid), can help to identify bleeding source more effectively without increasing the baseline irrigation pressure (Figure 1). If multiple attempts fail to control bleeding, other hemostasis techniques should be considered instead. The irrigation fluid can also be supplemented with epinephrine to provide some vasoconstrictive effect. We use 1 vial of 1mg epinephrine and add it to a 3-L bag of normal saline for this purpose. We use normal saline as the irrigation fluid for its higher sodium content for RF probe to function effectively. Fujita et al. [5] demonstrated that the irrigation fluid used in surgery affects bleeding at the surgical site, and that the calcium and potassium content of irrigation fluid seem to be important in hemostasis. They proposed using lactated Ringer solution or artificial cerebrospinal fluid as irrigation fluid instead of normal saline. The suitability of these 2 solutions as irrigation fluid has yet to be confirmed in endoscopic spine surgery, and is an area for future study.
A port with dual irrigation channels, with one channel connected to continuous irrigation, and another channel connected to a syringe, which allows intermittent flushing.
2. RF Probe
RF probe works well in achieving point hemostasis especially bleeding from small blood vessels or soft tissue/bone (Figure 2), without significant damage to surrounding structures. It provides low temperature coagulation with no carbonizing effect. Routine check of the probe should be done at the beginning of surgery to ensure that the probe is working properly, as evident by the bubbling in the irrigation fluid. When the probe is not working, all connections should be checked to ensure there is no loose connection. There should be adequate contact between the RF probe and the bleeding point for the probe to effectively stop the bleeding. Brief, intermittent and precise bursts are recommended at the lowest effective energy for the region of interest. In our series of cases, we use Joimax Vaporflex (bipolar spine coagulation) with an energy setting of up to 60 W for hemostasis above the ligamentum flavum, and settings between 15 W to 30 W when using the probe below the ligamentum flavum to reduce the risk of electrothermal injury to the nerve roots and the thecal sac. While RF is an effective method for coagulation, it carries the risk of iatrogenic thermal nerve injury if not used cautiously. Therefore, maintaining heightened vigilance during RF utilization is essential to mitigate the risk of any potential injuries [6].
The use of a radiofrequency probe for point bleeding from a small blood vessel adjacent to a nerve root.
3. Flowable Hemostat
Flowable hemostats may be used to stop bleeding that cannot be effectively localized and stopped by coagulation. It provides a thorough coverage of the bleeding sites that easily conforms to the topography of the underlying tissue [7]. Using flowable hemostat has been shown to reduce both intraoperative blood loss as well as postoperative hemorrhage [8]. Analysis of 2 flowable hemostats found that surgery time, risk of blood transfusion, and amount of hemostat used is lower with Floseal in comparison to Surgiflo [9]. In endoscopic spine surgery, Floseal may be considered as an appropriate adjunct to achieve hemostasis in tissue with limited or difficult access with instruments, bearing in mind that they do not flow against gravity, and its effectiveness may be affected by irrigation. There can be several modified techniques for the proper use of flowable hemostat during endoscopic surgeries. A long applicator is required (Figure 3A), and surgical patties can be used to help holding Floseal against the bleeding surface (Figure 3B). Alternatively, Floseal can be injected into operative view with irrigation inflow clamped. In either way, after allowing several minutes, the majority of bleedings can be controlled, and this maneuver can be repeated if necessary. Additionally, new products have been introduced as alternatives to Floseal, offering equivalent effectiveness [10].
(A) A long applicator is used to apply Floseal into the surgical field. (B) A surgical pattie is used to hold Floseal against the bleeding surface to achieve hemostasis.
4. Drilling/Kerrison Rongeur
Bone bleeding commonly occurs during spine surgery and may result in continuous slow oozing of blood from the exposed surface of cancellous bone. As the bleeding vessels are usually located within the spongy bone trabeculae, it cannot be compressed, making bipolar coagulator (RF probe) less effective for bone bleeding at times. When there is bleeding from bone surface and bipolar coagulator fails to stop the bleeding, we can use low speed drilling with a diamond burr directly over the bleeding point to stop the bleeding. A fine grit diamond burr works better than a coarse grit one for hemostasis purpose. It is also advisable to achieve adequate bony decompression prior to flavectomy to ease the process of hemostasis. However, caution should be taken to avoid overdrilling. Alternatively, a Kerrison ronguer can be used to compress the bleeding bone without cutting it. This compression action stops bleeding by sealing the area of bleeding within the cancellous bone. Both techniques were described in details by Hofstetter et al previously [11].
5. Surgical Patties
Surgical patties are useful tools in hemostasis. When placed in the surgical field, they can absorb blood and keep the field clean, for easier identification of the bleeding source. This is useful especially when there is large amount of blood in the surgical field and the irrigation is unable to demonstrate the anatomy effectively. One of the most problematic and difficult-to-control type of bleeding in spine surgery is epidural bleeding. The source of bleeding is usually from epidural venous plexus, which are longitudinally located beside the thecal sac. These vessels are usually thin and fragile, and can cause significant bleeding when damaged. Although bipolar coagulator is generally recommended for vessel bleeding, it can be technically challenging to place the tip of the coagulator precisely at the bleeding point, especially when there is massive bleeding. Due to the location of those vessels and its proximity to the nerve roots and thecal sac, the surgeon also needs to be very cautious when using the coagulator. Under such circumstances, placing a surgical pattie at the epidural space is helpful in clearing the bleeding storm and allowing the surgeon to identify the bleeding point (Figure 4). It also serves as an insulating barrier between the coagulator and the thecal sac/nerve root, when coagulator is activated for hemostasis. We use small or micro patties in our series of endoscopic spine surgery in view of the small endoscopic working channel, and they can be delivered to the intended point through the working channel of the endoscope.
(A) Epidural bleeding obscuring the surgical view. (B) The placement of a surgical pattie helps to absorb blood and keep the field clean, enabling easier identification of the bleeding source and subsequent hemostasis.
6. Bone Wax
Bone wax stops bone bleeding by mechanical intercalation within trabecular bone. The trabecular bone, located at the center of the bone and covered by cortical bones, is typically rich in blood supply, making it prone to easy bleeding. Utilization of bone wax in endoscopic spine surgery has been limited due to its physical property and difficulty in handling when working through a narrow channel. It sticks easily onto the wall of the working channel of the endoscope, and may result in clogging up of the channel, or bone wax sticking onto the lens and obstructing the surgeon’s view. We developed a modified bone wax application technique in endoscopic spine surgery, by using a “bone wax on pattie” (BWOP) method to avoid bone wax sticking onto working channel/lens, as well as allow easier application of bone wax onto the bleeding bone surface.
A stepwise description of the BWOP technique is provided below.
Step 1: the endoscope is removed from the port and an endoscopic grasper is inserted through the working channel until the grasper comes out from the other end of the channel.
Step 2: under direct vision, use the grasper to hold a small square pattie, and stick a small piece of bone wax onto the pattie surface (Figure 5A).
(A) With the endoscope removed from the port, an endoscopic grasper is inserted through the working channel to hold a small square pattie with a piece of bone wax on the pattie surface. (B) A pattie and bone wax is delivered into the surgical field under endoscopic visualization. (C) A grasper (or any other feasible instrument) is used to push the pattie and smear the bone wax onto the bleeding bone surface until bleeding stops.
Step 3: hold the endoscope with the grasper inside the working channel as one unit, and insert them through the port under endoscopic visualization to the surgical field (Figure 5B).
Step 4: use the grasper and pattie to push the bone wax onto the bone, and smear it around the bleeding bone surface repeatedly until the bleeding stops (Figure 5C). The surgical pattie is then removed with the grasper.
7. Others
Implementing adapted methods, like transsuperior articular process approaches for transforaminal surgeries, can prove advantageous in terms of bleeding control. This strategy entails targeting an anatomical region with minimal arterial distal branches, particularly the ventral aspect of the superior articular process [3]. Therefore, employing this technique can further reduce the risk of encountering arterial bleeding.
A surgical drain is generally not required in endoscopic spine surgeries, and surgeons must always try to achieve adequate hemostasis before skin closure. However, in some cases, it can be considered if there is concern of higher risk of postoperative bleeding, such as multilevel decompression, or if patient is on anticoagulation medication that needs to be resumed soon after surgery is done. The drain should be inserted under direct endoscopic visualization in those cases if indicated. At present, Liu et al. [12] showed that there is no significant benefit in drain insertion for endoscopic lumbar discectomy in reduction of epidural fluid collection.
Last but not least, we recommend removing the endoscope slowly, inspect the surrounding tissue carefully to look for bleeding points and perform meticulous hemostasis, until there is no visible bleeding and the endoscope and port are removed. This extends beyond the area of neural decompression to encompass surrounding structures such as muscles, bones, and the subcutaneous tissue. The residual irrigation fluid can be removed by manual compression of paraspinal area around the wound. The incision is then closed, and dressing is applied. However, hemostasis along the port removal can only be performed via uniportal surgery as the working channel and endoscope is along the same axis, unlike in biportal surgery.
DISCUSSION
Endoscopic spine surgery has been proven to be an effective minimally invasive procedure with the advantage of shorter hospital stay, reduced blood loss/paravertebral muscle dissection/perioperative pain, and lower revision rate as compared to microscopic tubular or open surgery. It can be performed via an uniportal or biportal approach with the aim of discectomy and decompression. With the aging population globally, endoscopic surgery can be offered as a reliable alternative for patients above 70 years old [13]. However, incidence of epidural fluid collection or hematoma should not be underestimated with reported incidence of 23.6%–90% [12,14,15]. Despite the high incidence of postoperative epidural fluid collection shown in postoperative magnetic resonance imaging (immediate or postoperative day 1), the actual clinical significance of epidural hematoma leading to revision surgery is low [12,14]. Wu et al. [15] showed that in his series of uniportal lumbar endoscopic surgeries, 27% of patients had postoperative epidural collection, but only 0.2% (3 out of 126) suffered from higher visual analogue scale score with no neurological sequalae.
The importance of hemostasis certainly still needs special attention in view of known risk of epidural collection/hematoma. Hofstetter et al. [11] had previously discussed hemostasis systematically in full endoscopic spine surgeries in 2020. In their discussion, the bleeding point should be identified, a bipolar coagulator was considered most effective when compressing the bleeding vessel with the tip of the bipolar, while simultaneously activating coagulation. Alternatively, if the bleeding is coming from the bone, the bleeding bone could be sealed off by using a diamond burr or by compression with a Kerrison rongeur. If these 2 maneuvers fail to stop the bleeding, it was suggested that irrigation pressure can be increased and advancing the endoscope towards the bleeding point can allow better visualization and hemostasis. If all of the above failed, injection of thrombin and Floseal into the working channel can be considered as a last resort.
This step wise approach to hemostasis is useful and effective for majority of the bleeding we encountered. However, sometimes we may encounter persistent bone bleeding that is difficult to control, and may need other methods to achieve successful hemostasis.
Chu et al. [16] previously described a technique of smearing bone wax onto the ball tip of the drill and using it for hemostasis in endoscopic cervical spine surgery in their report in 2018. However, bone wax may stick onto the wall of the working channel or onto the lens of the endoscope, thus obscuring the surgeon’s view. In 2023, Inoue et al. [17] introduced a new technique of using a nozzle applicator to deliver the bone wax to the bleeding target, while minimizing the risk of bone wax clogging up the working channel or sticking onto the lens. The drill burr was then used to push the wax onto the bone, and low speed drilling was started to spread bone wax around the bleeding point to secure hemostasis. This method solved the problem of bone wax clogging up the working channel or sticking to the lens, thereby improving the surgical view and safety for subsequent hemostasis. However, using the drill burr to apply bone wax to the bleeding target can be difficult, and bone wax may come off the burr or the bleeding bone during the drilling process, especially with ongoing irrigation. This may result in bone wax loss and reduced effectiveness of hemostasis.
To further improve the effectiveness of hemostasis with bone wax, we demonstrated the BWOP method. Our method avoids putting the bone wax through the working channel as the bone wax is applied directly onto the pattie after the grasper is passed through the working channel, thereby avoiding clogging up the working channel or sticking onto the lens. In addition, with the help of surgical pattie, smearing the bone wax onto the bleeding surface is much easier comparing to smearing with other instruments such as a drill burr. Surgical pattie also helps to create a tamponade effect at epidural space and allows better visualization and more precise hemostasis of the bleeding point. As a result, the surgeon’s view under the endoscope is much improved, allowing safer and more effective progression of the surgery. However, we would like to highlight that the implementation of this method requires some experience in endoscopic spine surgery and practice, to allow the user to be familiar with using various instruments under the endoscope, and to handle pattie/bone wax under irrigation, when the texture and weight changes may make it difficult to handle.
CONCLUSION
In conclusion, postoperative epidural collection or hematoma may not be completely avoidable. However, meticulous hemostasis is essential to achieve good outcome in endoscopic spine surgery. We hope the hemostasis techniques summarized and described in this article could possibly help spine surgeons embarking on endoscopic spine surgery to overcome some of the difficulties in their learning journey. We also look forward to higher adoption rate of endoscopic spine surgery and further development in this exciting field.
Notes
Conflict of Interest
The authors have nothing to disclose.
Funding/Support
This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Author Contribution
Conceptualization: TCHT; Writing – original draft: TTF; Writing – review & editing: TTF, WKK, JML, TCHT