I. Technique of sheath operation
Sheaths can be divided into long and short sheaths according to their lengths. Short sheaths are generally used for simple imaging, and according to their therapeutic needs, there are also the Tumbledown sheaths for dealing with the contralateral lower extremity, the long Shuttle sheaths for dealing with the carotid artery, the Guiding sheaths for dealing with the renal artery, and the anti-fracture sheaths to. The sheaths have a side connection interface for intraoperative blood sampling, pressure monitoring, and injection of vasodilators or contrast media.
The guidewire is preferably placed so that the tip of the guidewire extends into the lumen of the puncture needle and is sufficiently far from the tip of the needle to ensure that the softer part of the guidewire tip extends into the arterial puncture site. After the puncture, fluoroscopy is performed and the guidewire is introduced into the desired position. The puncture needle is then removed, and the puncture site is compressed during removal. The guidewire is preferably flushed with heparin saline.
Select a suitable sheath, soak the sheath and the accompanying dilator in heparin saline, and flush the lumen. To start the procedure, close the switch on the lateral arm of the sheath tube. The dilator base needs to be locked to prevent it from withdrawing during sheath entry. Check whether the skin puncture site requires pre-dilation and verify that the guidewire is stiff enough to allow entry of the sheath. Use a sheath-matched guidewire to ensure sheath entry. If the sheath is thicker and longer, or if there is scarring in the inguinal region, use a stiffer guidewire. Regardless of the type of guidewire used, it is important to make sure that the guidewire is long enough to ensure that the softer part of the tip of the guidewire is inside the artery and the stiffer part of the main stem of the guidewire is inside the arterial puncture needle.
The operator uses one hand to gently compress the puncture site while the other hand pushes the arterial sheath down the guidewire into the skin and then into the artery. Continuous compression of the puncture site must be applied while the sheath is placed in the arterial Soap. The proximal part of the sheath must be pushed gradually into the artery to prevent bending of the sheath as it enters the tissue. Rotation of the sheath is required for both subcutaneous advancement and retraction of the sheath. The lateral tube of the sheath is placed in a convenient position, usually toward the operator, during sheath entry. If the base of the dilator loosens and withdraws while the sheath is being entered, the open end of the sheath can be forced into the tissue and may cause damage to the sheath itself and the artery. In this case, the sheath should be reassembled and reoperated. During this time, the arterial puncture site should be compressed until the sheath is felt to enter the artery, which will prevent subcutaneous bruising. After the tip of the sheath has entered the artery, reduce the amount of force used to enter. Resistance is felt when the sheath is pushed into the artery at the beginning, and subsequent entry is easy and smooth. If resistance persists, perhaps there is an error in the procedure and a fluoroscopy can be performed.
After the sheath is placed, it is flushed with heparin saline. The sheath lumen should be flushed frequently after imaging with a sheath tube. The lumen should be flushed immediately after any procedure. When working with large or tortuous vessels, it is best to secure the sheath to the skin with sutures to prevent possible slippage of the sheath in thicker or more tortuous vessels. If the catheter used is the same type as the sheath (e.g., a 5F catheter in a 5F sheath), then the catheter will completely obstruct the lumen of the sheath and it will not be possible to inject contrast and heparin saline through the lateral arm of the sheath. When entering the lumen, the position of the sheath tip should be clearly defined to prevent the balloon or stent from not extending out of the sheath and not being released. If the femoral artery puncture site is heavily calcified or has a lot of scar tissue around it, the guidewire may enter the artery easily, but the dilator or sheath may have great difficulty entering. In this case, the tip of the dilator may bounce back against the hard arterial wall and the entire puncture system, including the guidewire and sheath, may bend in the subcutaneous tissue. This is more likely to occur if the patient is obese and has scar tissue in the artery. The dilator should be introduced and the subcutaneous guidewire should be straightened. After the dilator is inserted, it may be necessary to change to a more rigid guidewire depending on the condition or the need to deliver the sheath.
Basic sheath type
The diameter of the guidewire is in inches. “035” means that the diameter of the guidewire is 0.035 inch. The available guidewire diameters are “0 1 0, 0 1 4, 0 1 8, 025, 035 and 038”. Each guide wire diameter has a matching catheter. The most commonly used guidewire sizes are “0 1 4 and 035”.
The unit of catheter is “French”. This unit is a description of the circumference of the catheter. The “French” system is based on the circumference, which is the ratio of the circumference of a circle to the diameter of that circle. The diameter of the catheter or sheath is obtained by dividing the “French” dimension of the catheter or sheath by the circumference or by 3. For example, the diameter of a 6F sheath is 2 mm and the diameter of a 24F sheath is 8 mm. Dividing by 3 converts the “French” dimension to the diameter of the arterial puncture site. Both dilators and catheters are described in terms of outer diameter (OD), while sheaths are described in terms of inner diameter (ID). The ID of a sheath indicates the size of the device that can pass through its lumen, e.g., a 5Fr sheath fits a 5Fr catheter. The standard 5Fr sheath sheath has an outside diameter of 6 or 7Fr, which is 1-2Fr larger than the vascular puncture site, but is of little practical clinical significance. Sheaths are available in a variety of diameters, commonly in the 4-6Fr range because of their size, and most diagnostic and ball expansion catheters fit this size. Sheaths of 6-8 Fr are usually required for stent placement, with 6-12 Fr being preferred for the iliac and superficial femoral arteries (SFA) and 22-25 Fr for the aorta.
Sheaths are available in various lengths: 3-5cm, 10-12cm, 22-25cm, 30-40cm and 90-lOOcm. 010-12cm is the standard length and is suitable for most peripheral vascular diagnostic and interventional procedures. 3-5cm is usually used for hemodialysis access. Medium lengths are suitable for the contralateral iliac or femoral artery and renal artery. These sheaths have a pre-formed head or are torsion resistant to facilitate access to the aortic bifurcation. Some manufacturers place radiopaque markers at the end of the sheath to facilitate fluoroscopic visualization. This is particularly important during interventions, for example, to know if the stent is fully extended before releasing the sheath. The longest sheaths can be used for both carotid and contralateral tibial artery interventions.
Precautions for the use of sheaths.
1. Before using the sheath, the sheath and dilator should be flushed and wiped with heparin saline.
2. Close the switch of the lateral sheath tube.
3. Confirm the sheath type repeatedly.
4.Lock the dilator completely or insert it to the base of the sheath tube.
5.Pre-dilate the skin entry point.
6.Check the type and position of the guidewire.
7.Pre-dilate the entry tunnel with the dilator.
8.The puncture point should be compressed when performing the sheath tube device exchange.
9.The sheath and dilator are delivered together to the body.
10.Deliver the guidewire.
11.Hold the main body of the sheath while inserting the sheath.
12.Rotate the sheath and gently enter the subcutaneous tissue.
13.Press the arterial puncture site until the tip of the sheath enters the artery.
14.The lateral tube of the sheath is oriented toward the operator.
15. Check the dilator on the sheath to confirm that it will not withdraw.
16. If there is resistance to delivery, stop immediately and check.
17.Insert the sheath up to its base.
18.After sheath placement is complete, the dilator is removed and the sheath is suctioned and flushed.
19.If there is blood oozing around the sheath, you can change to a larger sheath.
20.Do not use the sheath tube alone without dilator to enter.
21.If the tip of the sheath tube is damaged or irregular, it needs to be replaced promptly.
22.Sew the sheath to the skin to prevent it from slipping out (usually not used).
23.If the catheter completely fills the lumen of the sheath tube, fluid should not be injected into the lateral tube.
24.The position of the sheath tip in the lumen of the vessel should be clarified.