Hemostasis is the process in which blood is maintained in a fluid state and confined to the vascular system. Maintaining hemostasis during laparoscopic surgery is required to help maintain adequate visualization and to optimize patient outcomes. In laparoscopy, like open surgery, several modes of hemostasis are available. Familiarity with each of the various forms of hemostasis, including a basic understanding of the mechanisms behind their use, will ensure proper usage and prevent unforeseen complications.
Methods of Hemostasis
The application of direct pressure using a blunt laparoscopic instrument (e.g. a 5-mm atraumatic grasper) to control a bleeding point is often the first manuever used to achieve hemostasis in laparoscopic surgery. This temporarily halts blood loss by tamponade and affords the surgeon time to adequately visualize the area of interest. Local physiologic responses to direct pressure also initiates the process of primary and secondary hemostasis leading to platelet aggregation and fibrin formation. Depending on the size of the blood vessels involved and the patient’s coagulation status, this may be all that is required to achieve hemostasis in select situations.
Endoscopic Clip applier
In cases where clips are known to be required (e.g. laparoscpopic cholecystectomy) both 5 mm and 10 mm reusable and disposable clip appliers are available. Most mechanical clips are metallic (titanium), although there are some forms of non-metallic clips that are available for use during minimally invasive procedures. The choice of which type of clip and applier to use is surgeon dependent and should be tailored to the anticipated size of the vessels that need to be clipped. It is advised that even in cases where clips will not be required, a clip applier be readily available in the event of unexpected hemorrhage.
Prior to clip appication, visualization of both sides of the clip is important to ensure adequate tissue purchase and inadvertent clipping of non-target tissue. Inadvertent ischemic necrosis, perforation, and laceration of surrounding tissues can occur as a result of inattentive clip application.
Linear stapling devices
Endoscopic stapling devices are very useful in situations where mechanical clips are not sufficient to envelop larger blood vessels, particularly when the vessel is to be ligated. Smaller height staples (2.0 mm or 2.5 mm) have been designed for this purpose.
Pretied suture loops
Proper use of suture loops requires division of a bleeding vessel or vascular pedicle in order to loop around the area of interest. This makes this form of hemostasis suboptimal in situations where the vessels are intact and ideal in the control of hemorrhage from a vessle that is already ligated. Permanent, absorbable, monofilament, and braided sutures are all available.
Surgeons that are adept at tying suture outside (extracorporeal) or inside (intracorporeal) the body during laparoscopic can use simple suture ligatures for hemostasis. Extracorporeal techniques require suture lengths greater than 70 cm. Intracorporeal sutures are cut to 5-7 inches. As in open surgery, care must be taken during both of these techniques to ensure that the forces used to complete the task do not lead to “sawing” of the tissue. In particular, the excessive upward forces that can be seen during the passing and redelivery of suture through a trocar during extracorporeal suturing can be avoided with the use of an instrument serving as a fulcrum placed in proximity to the tissue.
As in open surgery, when tissue approximation will result in hemostasis, suturing is a valuable adjunct to the methods listed above. Again, both extracorporeal and intracorporeal methods can be used depending on the surgeon’s preference and experience with a given technique.
Energy-Induced hemostasis refers to the process whereby an energy source is delivered to tissue in a predictable way leading to hemostasis through thermal tissue destruction. The temperature attained in the tissue predicts the type of changes observed. Specifically:
- At 45 degrees centigrade – collagen uncoils and may reanneal, allowing apposed edges to form covalent bonds and fuse.
- At 60 degrees centigrade – irreversible protein denaturation occurs and coagulation necrosis begins. This is characterized by blanching in color.
- At 80 degrees centigrade – carbonization begins and leads to drying and shrinkage of tissue.
- From 90 to 100 degrees centigrade – cellular vaporization occurs and vacuoles form and coalesce, leading to complete cellular destruction. Water vapor is seen.
- Above 125 degrees centigrade – complete oxidation of protein and lipids leads to carbon residue or eschar formation
Electricity is the most frequently used energy source during surgical interventions. This process is dependent on the creation of an electrical alternating current generated from electrosurgical (ESU) units. This current is then passed through a circuit that is composed of the ESU generator, an active electrode, the patient, and a patient return electrode. The amount of heat generated within the circuit depends on the amount of impedance (the inverse of resistance) within the tissue and the current density (amps/cm2) at any given point. The heat generated is highest at the the small areas of contact where the current has to be concentrated in order to overcome the impedance, and lowest along the larger contact areas (e.g. the grounding pad) where current is allowed to spread out and flow through a larger area with less current density.
The amount of heat generated can also be altered by changing the waveform of the current (e.g. cut vs. coagulation modes). Cut mode uses a continuous waveform (high frequency, lower voltage) and generates a large amount of heat rapidly (up 90 – 120 degrees centigrade). Coagulation mode has an intermittent pulsed wave form (low frequency, higher voltage) with a reduced “duty cycle” or time it generating heat. This will lead to lower temperatures with differing effects on the tissue (e.g. coagulation necrosis and carbonization instead of vaporization). Different types of ESU’s can vary the amount of the “duty cycle” in a “blended current” mode with lower duty cycles generating more heat.
It is important to remember, that the primary differences between cut and coagulation modes involves the amount of heat generated. Given that current density is also a component of heat generation, it is possible to be set in “coagulation” mode while generate temperatures high enough to mimick the “cut” setting. For example, the tip of an L-hook cautery instrument can generate “cut” like temperatures even in coagulation mode. This is different if one uses the outer side back-end of the L-hook because it has a larger surface area and will therefore have a lower current density.
Monopolar electrosurgery is frequently used in laparoscopy, and the choice between this or bipolar electrosurgery is based on surgeon preference. This form of electrosurgery involves current from an active electrode (e.g. hook, spatula, activated scissors, etc . . .) passing through the patient and returning through a large grounding plate.
In this form of electrosurgery, the active electrode can be intermittently apposed to the return electrode (e.g. in a forceps-type arrangement). Electrical current passes between the electrodes to complete the circuit. The flow of currently beyond the surgical field is minimal.
The LigaSure Vessel sealing system (Valleylab, Boulder, CO) uses a form of bipolar current that is locally modified through feedback control on the ESU. As the resistance of the tissue changes as it is being dessicated, the generator adjusts the pulsed energy appropriately. This allows for high current with low voltages – effectively melting collagen and elastin and creating a seal that allows hemostatic division of tissue.
Ultrasonic instruments like the cavitational ultrasonic aspirator (CUSA), and the ultrasonic scalpel are examples of instruments that use ultrasonic energy to provide hemostasis. These instruments use high frequency (> 20,000 Hz) to induce mechanical vibration at a cellular level. This energy is transferred into heat due to friction and shear. For example, the ultrasonic scalpel uses a piezoelectric ceramic element that expands and contracts at a rate of 55,500 Hz. This is transferred to a metallic blade that oscilates to generate the friction and shear needed to produce heat. Ultrasonic coagulating shears have been developed to facilitate both coagulation and ligation of unsupported tissue. Like the electrosurgical devices, there is a cutting mode (high power setting) and a coagulation mode (lower power setting) that are available for differing situations with usage based on surgeon preference.
Prevention of Hemorrhage
- Avoid blunt avulsion of unknown structures
- Safe and selective application of energy to the area to be divided can be preemptive
- Clearly identify the structures you are dividing. If the structure is unknown and appears vascular – precautions to either avoid division or provide preemptive ligation are required.
Management of Active Hemorrhage
The algorithm for handling active hemorrhage in the most recent SAGES Manual is as follows:
- Visually identify the bleeding without moving retraction
- Suction the area with a large-bore suction device. Irrigation should be minimized in active bleeding. In select instances the insertion of a sponge through a 10 mm port site may help to tamponade bleeding and absorb pooled blood.
- Apply a atraumatic grasper to the bleeding point where identified.
- If you are not able to stop the bleeding with manuever #3 (direct identification and pressure), convert to an open procedure.
- If you are able to control the bleeding with maneuver #3, ensure that there are enough port sites for adequate instrumentation. Consider extra ports for better visualization and retraction, and possibly for optimal triangulation if suturing is required.
- Place a mechanical clip on both sides of the area being grasped in #3.
- Irrigate and evaluate
Depending on the amount and rate of hemorrhage, direct application of electrical and ultrasonic energy has also been advocated. Additionally, although mechanical clips are generally secure, if you expect to perform multiple manipulations near the area of clip placement, the clips could be inadvertently knocked off. In these situations, it may be necessary to consider a suture ligature or a pre-tied suture loop.