There are five factors influencing patency. The first and most important factor is the catheter tip position. The other four factors are: the use of a closed system such as the Vascular Access Button™ (VAB™), catheter material and tip profile, the use of sterile components including your flush and lock solutions and the use of the positive pressure technique when locking the catheter. Learn more
Aseptic technique and using sterile supplies and solutions is non negotiable when it comes to survival surgery and catheter maintenance. Using non sterile supplies and lock and flush solutions may lead to infections and decrease patency duration. Learn more
If positive pressure is not used when disconnecting the syringe from the VAB™’s port, blood will enter in the catheter and may clot, leading to catheter blockage and loss of patency. See this blog and video for more information
The term ‘French’ (Fr, Fg, FR, F, CH or Ch) is a unit of measure invented by Joseph-Frédéric-Benoît Charrière, a Swiss-born French manufacturer of surgical instruments. His name Charrière was difficult to pronounce for people who did not speak French, leading to naming the unit of measure French instead of Charrière.
1Fr equals 1/3 or 0.33 mm of the catheter’s outside diameter, 2Fr equals 2/3 or .67 mm of the catheter’s outside diameter, 3Fr equals 1 mm of the catheter’s outside diameter and so forth.
As a general rule, the maximum of blood that should be withdrawn for one sample should not exceed 10% of the circulating blood volume. If more samples are needed, a recovery period of 3-4 weeks should be allowed in between samples.
As a general rule, for multiple samples on mice and rats, no more than 1% of the circulating volume per day can be withdrawn.
Catheter patency duration is affected by multiple factors. If all factors are followed, patency for all vessels in both mice and rats, can last many months. Read the Five Keys to Patency
PU is the material of choice because of its biocompatibility. PU is a happy medium between silicone and polyethylene. It is less porous than silicone and less rigid than polyethylene. It is also the best material for subcutaneous connections, such as when the catheter is attached to the VAB™’s connector. Learn more
A round tip catheter, compared to square or bevel tips, is less traumatic to the lining of the blood vessels and therefore, increases patency duration. Learn more
The main purpose of the collar (also called bead) on the catheter is to define the catheter insertion length. It also serves as an anchor by placing sutures rostrally and caudally to it during surgery. Our catheters come with either a fixed or movable bead. Make sure you order the ones that will best fit your needs. See all Catheters
When using a closed system such as with the VAB™, the recommended maintenance schedule is seven days. If your catheter is exteriorized, or if using an open system, the catheter should be maintained every three to four days.
Sterile isotonic saline solution or sterile heparinized isotonic saline solution (usually at a low heparin concentration of 10 or 20USP/ml) are used as flushed solutions during surgery, catheter maintenance or after compound infusion.
The 500 IU/mL Heparin/Dextrose or Heparin/Glycerol lock solutions have been widely used and have been evaluated, as seen in the CRL/Dr. Luo study from 2000, for example. In that study, catheters were implanted in the venous system, more specifically in the femoral vein, and were exteriorized and sealed with plugs resulting in an open system. The high viscosity of the Heparin/Glycerol lock solution prevents evaporation of fluids in the exteriorized catheter while the Heparin/Dextrose solution minimizes bacterial growth. These two solutions are desirable with an open system, but they are not necessarily needed nor an advantage when using a closed system as provided by the Vascular Access Button™. When using a VAB™, the catheter completely lies subcutaneously, negating the need to prevent fluid evaporation. Additionally, the septum of the VAB™’s port provides a closed system which offers a clean way to connect to the vascular system, consequently minimizing the risks of infections.
When using a high heparin concentration solution there is a risk of introducing hazardous amounts of heparin into the bloodstream. Therefore, the best approach might be to use a lower and safer concentration heparin solution such as the 10 or 20 IU/mL heparinized saline (called flush solutions) with the VAB™ in the venous system to lock the catheter. This formulation is available in the form of pharmaceutical-grade, easy to use prefilled sterile syringes.
The high viscosity of the Heparin/Glycerol solution may be beneficial for the arterial system as the high blood pressure present in the arteries may cause blood to infiltrate into the catheter and form a thrombus. Instech has formulated a lock solution which consists of glycerol with a lower concentration of heparin at 50 IU/mL in order to prevent hazardous amounts of heparin into the bloodstream. This formulation is available in the form of vials with or without Instech’s needle-free PinPort™ technology built into the cap.
In summary, when using a VAB™, the 10 or 20 IU/mL heparinized saline flush solution is getting more and more popular as a lock solution, especially within the venous system. The heparin/glycerol may be beneficial in the arterial system and the low heparin formulation minimizes the risk of introducing hazardous amounts of heparin into the bloodstream. The bottom line is, choose and use the lock solution that works best for you and your animals. There are no set rules when it comes to which solutions will perform best in different species or vessels, but remember to be cautious if you opt out for a high heparin concentration lock solution.
The dead volume is 0.3µl per centimeter.
The dead volume is 1.5µl per centimeter.
The dead volume is 3µl per centimeter.
Yes, the flow of fluids in rodent catheters is almost always governed by laminar flow. In laminar flow, fluid at the center of the tube moves faster than fluid at the edge which is held up by contact with the tube wall. This means that you may have to increase the volume of the lock solution to ensure the catheter’s dead volume is completely filled. The more viscous the solution is, the more laminar flow effect you will have. See this blog for more information.
Yes! Instructions for use are available for both mouse and rat VABs™ and can be accessed through the following links:
Mouse VAB™ Instructions for Use | Rat VAB™ Instructions for Use
There are many reasons why you should use a VAB™. Low-stress sampling and infusion, extended catheter patency duration and the possibility of group housing your animals with the addition of the metal cap on the VAB™’s port. Learn more
Part Number |
VABR1B/27 |
VABR1B/25 |
VABR1B/22 |
VABR2B/22 |
VABR3B/22 |
VABR4B/22 |
White Port |
2µl | 3µl | 4µl | 4µl | 4µl | 4µl |
Red Port |
4µl | 5µl | 4µl | |||
Blue Port |
4µl | 4µl | ||||
Green Port |
4µl |
Part Number |
VABM1B/25 |
VABM1B/22 |
VABM1BSM/25 |
VABM2JB/25R25 |
VABM2JBSM/25R25 |
White Port |
3µl | 4µl | 3µl | 2µl | 2µl |
Red Port |
2µl | 2µl |
The total circulating blood volume of a rat is, on average, 64 ml/kg. The blood volume for a 250 g rat is ~16ml, therefore the volume for one sample should not exceed 1.6ml.
The total circulating blood volume of a mouse is, on average, 58 ml/kg. The total blood volume for a 25 g mouse is ~1.45 ml, therefore the volume for one sample should not exceed 0.15 ml or 15 µl.
Yes, we recommend soaking the felt disk aseptically in sterile saline prior to its subcutaneous implantation. Placing it in sterile saline when starting the procedure will ensure an appropriate saturated disk. A dry felt disk may cause some irritation to the adjacent tissues.
Download the Rat VAB™ Instructions for Use
Download the Mouse VAB™ Instructions for Use
Yes, the metal caps can be cleaned, autoclaved and reused multiple times.
Metal caps can occasionally adhere to the VAB™ base due to dried fluid buildup from the surgical site. It can also occur if a dextrose lock solution is used. To loosen the cap, apply warm sterile saline to the site with a syringe or with some sterile swabs saturated with sterile saline. If needed, sterile forceps can be used to help in breaking the dried buildup of fluids or lock solution.
No, for numerous reasons, it is not practical to reuse the VAB™ on multiple animals. In most cases, tissues will grow into the felt disk and there will also be blood on it which will make the VAB™ impossible to be cleaned and reused. Second, there is absolutely no way to guarantee the internal port and its septum are completely clean in order to avoid cross-contamination. If you are practicing and not recovering animals, it is fine to reuse your VAB™ throughout the day.
Our Vascular Access Buttons™’s ports have been tested and can be punctured over 200x over its lifetime.
Yes, the VAB™ can be connected to a vein or an artery. It can also be connected to an organ such as the intestines and a duct such as the bile duct.
The ideal tip placement for a jugular vein catheterization is the entrance of the right atrium. See this blog for more information
The ideal tip placement for a carotid artery catheterization is the entrance of the aortic arch. See this blog for more information
The ideal tip placement for a femoral vein catheterization is in the inferior vena cava caudal to the renal veins.
The ideal tip placement for a femoral artery catheterization is the abdominal artery caudal to the renal arteries.
The catheter tip location can be predicted by measurements carried out on cadavers prior to performing the survival surgery. Such measurements should be taken from anatomical landmarks or measurements from anatomical landmarks to the ideal catheter tip location. These measurements will become the catheter insertion length and the collar (or bead) on the catheter should correspond to the insertion length.
The catheter is secured in place by tying both the rostral and caudal sutures around it. The caudal suture is tied over the catheter and vessel. The rostral suture, which was used to ligate the vessel, is then tied over the catheter itself.
Non absorbable suture must be used for these purposes. Silk is used as it provides the best knot security for a non absorbable suture. 6.0 silk works very well for these applications in both mice and rats.
The jugular on the animal’s right side should be used for catheterization. When accessing the right atrium, the right jugular vein is a more direct, shorter route compared to the left jugular vein.
The carotid on the animal’s left side should be used for catheterization. If the right carotid is used, it will occlude/partially occlude blood circulation to the subclavian artery as they both originate from the brachiocephalic trunk (also called the Innominate artery). The brachiocephalic trunk originates from the aortic arch. The left carotid artery originates directly from the aortic arch making it the best selection.
It does not matter as much with the femoral vein or artery as there are no anatomical differences between the right and left sides.
es not get in the way of animal movement (if placed too rostrally for example) and that there is some slack from the catheter to allow for growth and movement of the animal.
The VAB™’s felt disk should be placed subcutaneously in the animal’s interscapular area.
Most surgeons orient the VAB™ connector caudally (toward the tail) of the animal. But we have also seen some surgeons orienting it rostrally (toward the nose) or laterally. There is no right or wrong, but ensure the connector does not get in the way of animal movement if placed too cranially, for example. Ensure there is some catheter slack to allow for animal growth and movement.
Seromas are caused by forming an overlarge subcutaneous pocket for the VAB™’s disk. This generates dead space which will later be filled with an abnormal accumulation of serous fluids. Seromas are seen most commonly in rats and not in mice.
Making the subcutaneous pocket the right size for the VAB™’s disk is the best way to prevent seroma formation. Also make sure the pocket is not too small as this can put some pressure on the skin causing irritation or worst, pressure necrosis of the skin.
An experienced surgeon takes about 20 minutes to complete the entire procedure. As a general guideline, anyone planning on performing survival surgery should practice without recovering animals until reaching approximately 30 minutes per procedure.
Yes, Instech has launched an education program and now provides virtual surgical training. Learn more
A microscope is the best tool to perform an atraumatic surgery. It allows you to see fine details that could not otherwise be detected with the naked eye. It also enables you to be ergonomically correct when performing the procedure. A microscope with a tilting binocular head is ideal as it further helps with ergonomics. You should also have an illumination source such as a microscope ring light or a dual gooseneck fiber optic light.
Micro instruments such as those sold by Fine Science Tools (FST) are ideal to perform catheterizations on rodents. For ease and convenience, Instech and FST collaborated and put together these Vascular Catheterization Surgical Packs.