FAQ 1: Why is there more flow with a smartcanula as compared to a standard canula or a percutaneous canula?
There are three main factors that contribute to the superior performance of the smartcanula:
(1) the self-expanding mechanism allows for a larger smartcanula diameter wherever the vessel lumen is wide
(2) the wall thickness of the smartcanula is far less than in any other canula allowing for superior effective luminal width
(3) the uncovered „open wall“ design of the smartcanula allows for direct drainage of the blood coming from collaterals.
FAQ 2: Is there more haemolysis with the smartcanula?
No, there is not more haemolysis with the smartcanula as compared to other canulae because there is not only a larger mean effective luminal width but also the total orifice area is at least one order of magnitude higher. Both factors contribute to lower velocities and less stress (see also literature for experimental and clinical data).
FAQ 3: For how much time can the smartcanula be used?
Typical use of the smartcanula is two hours and maximal use is six (6) hours.
FAQ 4: Can the smartcanula be resterilized?
No, the smartcanula is designed for single use. It cannot be resterilized.
FAQ 5: How can the self-expanding smartcanula be removed?
smartcanula removal is easy, because simple traction reduces its diameter.
FAQ 6: How is the smartcanula inserted?
Each smartcanula comes with its specific mandrel in the same blister. Insertion of the smartcanula requires a guide wire, which is positioned in the target vessel area (e.g. vena cava superior for femoral canulation). Correct positioning of the guide wire has to be checked with echocardiography or other suitable means. The smartcanula is collapsed by extension with its mandrel and inserted over the guide wire previously positioned as described above. Once the smartcanula is in place, it is important to remove the guide wire before the mandrel in order to avoid dislodgement of smartcanula tip. For the patients safety, it is mandatory to read the instructions for use.
FAQ 7: What can I do, if a feel some resistance during removal of the guide wire?
Some resistance during guide wire removal can occur if the guide wire is kinked. For this reason, the guide wire should be removed before the mandrel in order to maintain the position of the tip of the smartcanula. If this is not successful, the guide wire, the smartcanula, and the mandrel have to be removed „en bloc“ (together) by gentle traction.
FAQ 8: How can I check the position of the guide wire and/or the smartcanula?
Suitable means to check the guide wire and/or the smartcanula position include echocardiography (transesophageal (TEE), intracardiac (ICE), epicardial, transthoracic), intravascular ultrasound (IVUS), fluoroscopy, digital exploration, etc.
FAQ 9: Why is there only one smartcanula diameter (15 F expanding to 36 F) for perfusion of adults?
It has been shown in the experimental and in the clinical setting that the venous smartcanula expanding to 36 F has sufficient drainage capacity (6 l/min) with gravity drainage alone. Hence, augmentation of venous return with a centrifugal pump or vacuum can be avoided.
FAQ 10: Is kinetic augmentation of the venous return recommended with the smartcanula?
With a well-positioned smartcanula in the right atrium (femoral, jugular or subclavian access is possible), gravity drainage is sufficient for achieving the target flow.
FAQ 11: Is one femoral venous smartcanula sufficient to achieve full flow?
Yes, one femoral venous smartcanula, well positioned in the superior vena cava/right atrium is sufficient to achieve the target flow with gravity drainage alone.
FAQ 12: Is one jugular venous smartcanula sufficient to achieve full flow?
Yes, one jugular venous smartcanula, well positioned in the inferior vena cava/right atrium is sufficient to achieve the target flow with gravity drainage alone.
FAQ 13: Is one subclavian venous smartcanula sufficient to achieve full flow?
Yes, one subclavian venous smartcanula, well positioned in the inferior vena cava/right atrium is sufficient to achieve the target flow with gravity drainage alone. Trans-subclavian insertion of the smartcanula may require curved catheters, as well as soft and stiff guide wires.
FAQ 14: For trans-subclavian smart canulation of the right atrium: What to do if the guide wire cannot be identified with echocardiography?
One possibility is that the guide wire progresses cranially. A curved catheter pointing caudally may allow for exploration of the superior vena cava with a J-type guide wire.
FAQ 15: For trans-subclavian smart canulation of the right atrium: What to do, if the guide wire is in the right atrium/inferior vena cava, but there is a resistance during insertion of the smartcanula?
One possibility is that the curve from the subclavian vein towards the superior vena cava is to narrow for the guide wire selected. This type of problem can often be overcome with a stiffer guide wire. For the purpose, an exchange catheter (e.g. a pig tail catheter) has to be sled over the guide wire which is in place. Once the catheter can be identified in the right atrium, the guide wire can be replaced with a super stiff guide wire, which in turn may allow to insert the smartcanula. Alternatively, a jugular (straighter) approach may be considered.
FAQ 16: What are the various venous smartcanula lengths good for?
For adults, the long venous smartcanula (63 cm, 53 cm) is designed for single femoral canulation of the right atrium/superior vena cava. The medium venous smartcanula (43 cm) is designed for femoral canulation of the inferior vena cava (tip position at the level of the hepatic veins). The very short smartcanula (26cm) is designed for jugular canulation of the superior vena cava. The main indication for the medium and very short smartcanula is dual canulation for open heart surgery with open right atrium. There is also a short smartcanula (34 cm) which is suitable for either single trans-subclavian or trans-jugular canulation of the right atrium or direct canulation of the inferior vena cava through the right atrium.
FAQ 17: What is direct canulation of the inferior vena cava through the right atrium with a smartcanula good for?
Full flow can usually be achieved with gravity drainage alone, provided an access orifice of 24 F to 28 F is made available for the smartcanula as compared to up to 51 F for standard two stage venous canulae.
FAQ 18: What are the indications for smart central canulation (right atrium/inferior vena cava) canulation)?
The main indications for central venous (= right atrial) smart canulation include lack of space for various reasons and/or a small/crowded right atrium from previous procedures. Smart canulation of the right atrium/inferior vena cava may also be indicated for assisted beating heart procedures, where the ventricles have to be lifted and/or stabilized.
FAQ 19: What can be done in a patient who is perfused with a smartcanula crossing the right atrium and the latter has to be opened?
Several options are available here. The vena cava and smartcanula can be snared down together on the side of insertion and a solution has to be found for drainage of the second vena cava. For a short period, this may be handled with the cardiotomy suction. Alternatively, a second venous canula may be necessary. Opening of the right atrium will reveal the snared smartcanula, which will re-expand once the snare is released.
FAQ 20: What are the indications for smart canulation?
We distinguish six main groups of indications for smart canulation:
a) small access surgery with remote canulation. This is the original indication for which the smartcanula has been developed. As a matter of fact, it is very difficult to achieve full flow with traditional percutaneous canulae despite augmentation of venous return with centrifugal pumps or vacuum whereas gravity drainage is sufficient after smart canulation.
b) remote smart canulation for (redo-) procedures with increased risk of cardiac injury allows for achieving full flow and decompression of the heart before entering the chest.
c) remote smart canulation for aortic surgery allows for superior flow which in turn results in faster cooling respectively rewarming of the patient.
d) remote canulation for open intra-caval procedures without snare.
e) central smart canulation of the right atrium/inferior vena cava for patients with small or crowded right atrium (smaller access) or assisted beating heart procedures (requiring lifting and/or stabilizing of the ventricles).
FAQ 21: Is it true, that open intra-cardiac surgery is feasible without snare around the vena cava canulated with a smartcanula?
Yes, open intra-cardiac surgery without snare around one vena cava is possible with the smartcanula. This is due to the fact that the drainage of the vena cava after remote smart canulation occurs close to the access orifice and not close to the heart as with traditional canulae. Although special attention to the venous return during open right atrial surgery without snare around the vena cave with the smartcanula is necessary to prevent/recognize a potential airlock, only little perfusionist intervention is usually required.
FAQ 22: How far should the smartcanula be inserted?
At least 10 mm of the covered part of the smartcanula have to be inserted into the vessel to be drained.
FAQ 23: How should the smartcanula be attached once it is inserted?
If a suture is used, it should be placed onto the silastic sleeve, preferably in the section where the latter is supported with wires. If a tape is to be used, the silastic sleeve is again the preferred location.
FAQ 24: How to resolve poor drainage after smart canulation?
There are a number of reasons that can explain poor drainage (corrective measures). These include
(a) malposition (check position and reposition if necessary)
(b) narrowing by a purse string or a suture (release suture)
(c) kinked canula or tubing (reposition)
(d) unexpected anatomic constriction (add additional canula)
(e) other (add additional canula)
FAQ 25: How about patents – https://smartcanula.de/patents/
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