Peripheral vein cannulation

Motto: ''If I'm trying to avoid something, I'm looking for a reason. If I'm trying to figure something out, I'm looking for a way.''

Indications

 * Securing potentially at-risk patients,


 * provision for diagnostic purposes (eg for iv application of contrast),
 * infusion therapy,
 * blood transfusion ,
 * parenteral medication administration,
 * parenteral nutrition ,
 * providing access for the introduction of a central venous catheter (CVC) from the periphery.

Contraindications
Contraindications include infection or injury at the puncture site or the presence of an arteriovenous shunt on the limb. A relative contraindication may be severe damage to the proximally placed veins, ignorance of the technique.

Venous access
For cannulation, we usually use short cannulas with a diameter of 14–26 G, which we insert into the superficial veins on the dorsum of the hand, in the kubitě, more rarely on the wrist, forearm, dorsum of the foot. In children up to the age of about 2, surface veins on the calva that do not have flaps can also be cannulated → the cannula can be inserted in any direction (but it is still better centripetally and always ato respect the laws of gravity). We use the veins on the volar side of the wrist only exceptionally - puncture or other manipulations in this area are really painful procedures. In a situation of great peril we can cannulate v. femoralis, v. jugularis externa or v. axillaris.

Overview of venous access points

 * Head + neck: v. supraorbitalis, v. temporalis, v. auricularis posterior, v. occipitalis, v. jugularis interna, v. jugularis externa, v. subclavia.
 * Upper limb: v. axillaris, v. cephalica, v. basilica, plexus venosus dorsalis manus.
 * Lower limb: v. femoralis, v. saphena magna, v. saphena parva, plexus venosus dorsalis pedis.

Technika
The prerequisite for success is calmness and patience. Puncture success is significantly affected by detection of the vein and preparation for the puncture. The conditions for a successful try can be improved by warming the limb (causes vasodilation), "knocking" (toning of the venous wall) or pumping of blood into the venous system when the limb is constricted (increasing the filling of the venous system). The relevant limb / head is fixed by an assisting nurse, who ties up the limb above the injection site with a rubber "tourniquet" to increase the venous filling. After filling the venous system, we insert the cannula inserted on the needle mandrel so that the needle hole points in the direction of blood flow = centripetally, the needle should form an angle of 10-30 ° with the body surface (more tangentially, i.e. at a lower angle for a new-born on the volar side of the wrist or forearm). The technique of inserting the cannula itself also depends on the size of the cannula and the type according to the manufacturer - e.g. For cannulas of type Braun 22 G right after blood appears in cannula, we pull the mandrel and continue with insertion of only our own cannula, it is better to insert Braun 24G without pulling on the mandrel, i.e. to "pull" the cannula along the mandrel into a vein or to continue the final insertion after the initial light insertion with a small amount of solution. For cannulas with a larger needle overhang above the end of the plastic cannula (e.g. Terumo brand), proceed so as soon as blood appears in the cone of the capillary, carefully insert the cannula with the needle about 1-2 mm deeper and only then extend the mandrel and insert your own cannula.

In infants, the venous pressure may be so low that even with a properly inserted cannula, blood won't flow freely, then we make sure that it is properly inserted by applying a small amount of solution. The cannulas with the narrowest lumen can be inserted with a small amount of solution at the same time. The pulled out mandrel should not be inserted back into the cannula, as there is a risk of perforation with the possibility of subsequent embolization of part of the cannula.

When inserting the cannula, it is also possible to take blood for various laboratory tests at the same time, it is also possible to take blood culture at the same time, if we insert the cannula under sterile cautery. We connect the inserted cannula to an infusion set or syringe and after the throughput test, fix it so that the injection site is clearly visible despite the fixation.

In young children, we fix the limb to a splint, paying attention to the gentle support of the limb, especially in the area of ​​bone prominences of the wrist and elbow, so that traumatization does not occur and a pressure ulcer does not occur during long-term fixation. In the area of ​​the head, it is advantageous to use for fixation of pruban.

The injection site must be inspected regularly, especially for the youngest children / newborns, a 1-hour inspection is required.


 * Rules of peripheral cannulation in points


 * Patience and calmness: try to calm the child as much as possible, wait for sufficient onset of action of the drugs when using analgesic sedation, and wait for adequate warming when the periphery is cold.
 * Choose the best available vein, preferably with a straight course (if possible, omit peripheral venectasia, veins where "someone has already been" or veins where their course cannot be estimated).
 * Consider whether to inject in the classic way or by the "raised visor" method.
 * Adequately stretch the skin = the subcutaneous tissue must not move, but at the same time the lumen of the vein must be visible (ideal is a condition where the subcutaneous tissue is taut and at the same time the vein is well filled → do not regret time, actively involve the nurse and position the vein in the ideal position).
 * Consider the direction of injection and the inclination of the needle.


 * Feed rate 5-6 / 37 mm in the classic way.


 * With the classic method, do not watch the entry of the needle under the skin unnecessarily long, it is better to watch the end of the capillary until a drop of blood appears.
 * Modify your own insertion of the cannula according to the type of cannula and the manufacturer.
 * Humility, humility, humility… or a good vein is only the one in which there is a cannula!

Notes on cannulation and difficult cannulation

 * Before using the cannula, it is a good idea to drive the mandrel into the lumen of the cannula several times so that the mandrel can slide freely out of the cannula during the actual cannulation.


 * If, for any reason, the movement is stopped in the middle of the way (in the classic way), it is better to put the cannula back just under the skin and start the injection again. We always "back up" in the same direction as the puncture to prevent possible damage to the vein on the way back.


 * If blood appears in the capillary cone only when "reversing", it is a sign that we have "passed" the vein, either by injecting too fast or too slowly, understretching or overstretching the subcutaneous tissue, or when the needle is tilted too much. We can still try to insert the cannula at the moment of the greatest return of blood, but the probability of success is already quite small.


 * If the blood does not appear in the capillary cone at all and blood starts to flow out of the injection point after pulling the needle out, is again a sign that we have "driven through" the vein. Most often with excessive skin tension or cold acres, but the cause can also be a rapid puncture or hitting the vein at a completely wrong angle than its direction.


 * In infants, toddlers or dehydrated children, it may happen that after cannulation blood will not flow out of the cannula after a drop of blood appears in our cone and we pull out the mandrel. If we are convinced that the injection was performed correctly, we do not pull out the cannula, but connect the connector and insert the cannula normally with the current injection. However, if we feel that the injection was performed incorrectly, it's a lottery whether to try to insert the cannula with a spray as in the previous case or to try to pull the cannula back slightly and insert it when blood begins to flow out of the cannula.


 * If our skin "piles up" at the beginning of the injection, we will interrupt the injection and start again after the skin has been perfectly stretched !!!


 * If we repeatedly and unsuccessfully move only in the subcutaneous tissue in an attempt to find the lumen of the vein, it is necessary to take into account the possibility of clogging the needle. Then it is better to either replace the cannula with a new one or rinse and then blow the needle with a good stream of air from the syringe. Rarely, a clogging of the needle can occur even after one attempt of "dry puncture".
 * If we are still moving under the skin during the puncture in order to find the lumen of the vein, it is necessary not to deviate too much from the original axis of the puncture. Otherwise, there is a great risk that we will stab the vein at the "wrong" angle and despite the presence of blood in the signal chamber, we won't be able to insert the cannula.
 * When cannulating in the dorsa area of ​​the hands or feet, especially in the youngest children, start the injection proximally enough (if the course of the vein allows) so that fixation of the signal chamber with the index finger of the right hand is possible just against the dorsum of the hand or foot. If we prick a lot distally, the signal chamber is "in the interspace" and the tip of the cannula can easily slip out of the lumen of the needle.
 * If we choose to cannulate the cubite and clearly do not see any suitable vein in this area, it is worth examining the cubite area palpably, as it is often possible to feel a strong venous trunk that may not be visible at all. If a "blue spot" shines in the cubite, which indicates the presence of a vein, but its course is not visible, it is again appropriate to try to clarify the course of the vein by palpation. From a general point of view, the cubite area is a grateful place for cannulation, except in patients with markedly motor restlessness, because the fixation of the veins in the cubite in a struggling child is far more complicated than in the dorsa area of ​​the hand or foot. In these cases, it is advantageous if the nurses fix the forearms even distally and the cannulated patient has both hands at his disposal (it is possible to better stretch the skin and at the same time it is better to manipulate the cannula itself after injecting a vein). The mediolateral traction of the underside of the forearm also allows better vein fixation but the traction must be moderate so it doesn't close the lumen of the vein,
 * It is also necessary to respect the laws of gravity, i.e. blood does not have to appear in the cone of the capillary if we prick "downhill" - this applies especially to the veins in the head area, when pricking the v. jugularis externa and children in the crib with a barricade.
 * If we cannulate a child whose acres are very cold, we must first warm the periphery thoroughly. When cannulating the veins on cold limbs, blood usually does not appear at all in the cone of the capillary, the place of the puncture often does not even bleed = the image of a dry puncture, but after the limb is heated, the puncture can start to bleed. Either way, the vein is canceled and even after warming up we have to look for another place to cannulate.
 * Cave! - when cannulating v. jugularis externa, do not rely on blood to appear in the cone (although this is often the case) → it is necessary to cannulate with an open sight. If I have the impression that I am in a vein, the needle should be pulled out.
 * After removing the metal needle, we prevent blood spillage by compressing the vein in front of the cannula tip with the index finger of the free hand.
 * If we inject a vein whose lumen is optimally visible only with minimal skin and subcutaneous tension, then it is necessary to take into account a small intraluminal pressure and therefore cannot rely on a drop of blood to appear in the capillary cone as a sign of proper penetration → better to puncture with an open sight and if I feel like I'm in a lumen of a vein, try to pull out the mandrel - if we're right, blood will start to flow out of the cannula and we can slide the cannula with the current flush into the final position.
 * In children with hippopotamus skin, it is better to cannula with a larger "start", i.e. about 0.5-1 cm (but too long a start and there is a risk of losing the ideal direction and angle of the cannula to the vein). We also prefer to cannulate "non-cooperating patients" with start-up.
 * Analgesic sedation should be considered very carefully in non-cooperating patients. Motor restlessness, of course, reduces the success of cannulation, rapidly, especially in thinner veins and veins in the cubite. In addition, the need to firmly fix the patient's limbs leads to excessive tension of the skin above the cannulation site, to a narrowing of the lumen of the veins and thus a greater probability of "passing" the vein. If the patient responds with a strong defensive reaction (usually flexion) during the initial injection → the cannulation is in the vast majority of cases unsuccessful (the skin wrinkles and twitches, a sharp movement changes the injection speed and the position of the vein). An alternative for these children are areas such as the head, the v. jugularis externa, but it is best not to regret the time and sedate the child adequately!
 * If it is inevitable to cannulate a vein where "someone has already been", then we always prick proximal to the original puncture and only when the lumen is sufficiently filled. If the lumen is not clearly filled, it may happen that the blood does not appear in the capillary cone at all, or rather appears only when reversing. In this case, you can try the method with an open sight and a "leap forward".
 * When cannulating the veins on the volar side of the forearm, we usually cannulate in the classic way, but we must choose a significantly tangential inclination of the needle, i.e. 10-15 ° and proceed at a slower speed within the "allowed" speed. When cannulating on the volar side of the wrist, we also choose a larger tangential slope, but we usually follow the "open sight" method.
 * When cannulating thin veins (newborns, volar side of the wrist, etc.) using the "open visor" method, common cause of failure is a too deep of an initial injection. It is best to guide the initial cannula for a short distance and immediately check for blood in the signal chamber.
 * When cannulating veins in the cubite in newborns, we achieve the best subcutaneous tension using the mediolateral pull or a combination of mediolateral and proximodistal pull. The proximodist pull alone is usually not able to ensure sufficient skin tension and cannulation is unsuccessful.
 * If we have to cannulate thin veins, it is generally true that: we prick with an open visor, in very thin veins the presence of blood in the capillary cone is often not expected. We can choose a purple 26 G cannula and in the extreme case we can insert only the tip of the needle with the hole into the vein and try to insert the cannula afterwards - the probability of success is significantly lower. It should be noted that the thinnest veins simply cannot be technically cannulated, so it is important to differentiate them and not get into them at all! Often, under thorough subcutaneous tension, a "non-cannulable" thin vein may falsely appear strong enough (it looks like a green-blue stripe without a general lumen), but an attempt to cannulate is always unsuccessful. The thickness of the vein must therefore be carefully assessed, both before and after the subcutaneous tension. If the vein appears to be too weak, it must be ignored. When assessing the thickness of a vein the lumen is more important then it's width.
 * If we have to cannulate thin veins, it is generally true that: we prick with an open visor, in very thin veins the presence of blood in the capillary cone is often not expected. We can choose a purple 26 G cannula and in the extreme case we can insert only the tip of the needle with the hole into the vein and try to insert the cannula afterwards - the probability of success is significantly lower. It should be noted that the thinnest veins simply cannot be technically cannulated, so it is important to differentiate them and not get into them at all! Often, under thorough subcutaneous tension, a "non-cannulable" thin vein may falsely appear strong enough (it looks like a green-blue stripe without a general lumen), but an attempt to cannulate is always unsuccessful. The thickness of the vein must therefore be carefully assessed, both before and after the subcutaneous tension. If the vein appears to be too weak, it must be ignored. When assessing the thickness of a vein the lumen is more important then it's width.

It should be noted that the thinnest veins simply cannot be technically cannulated, so it is important to differentiate them and not get into them at all!

U dětí, kde žíly nemají logiku, je lépe nechat iniciálně kanylovat sestry a nesnižovat si tak zbytečně sebevědomí sérií neúspěšných vpichů, kdy stejně nelze přijít na kloub správnému postupu (alespoň prozatím…)
 * Pokud v běžných oblastech vpichu, jako jsou dorza a kubity nelze nalézt žádnou žílu nebo je obtížné odhadnout jejich průběh, je vhodné se podívat na uvedené oblasti z opačné strany, tj. z pozice sestry. V klasickém případě lékař sleduje průběh vhodných žil směrem „od prstů k paži“, zatímco sestra „od paže k prstům“. Sestra proto zaujme pozici lékaře a příslušné končetiny zaškrtí, lékař zaujme pozici sestry. Nečekaně často tak můžeme objevit žíly, které z pozice lékaře zcela uniknou pozornosti nebo tak získáme lepší možnost odhadnout jejich směr.
 * Máme-li za sebou 3–4 neúspěšné pokusy je nutno se nejprve uklidnit, znovu najít nejlépe dostupnou žílu, přehodnotit dosavadní postup, zejm. rychlost a dále volbu mezi klasickou technikou nebo technikou se „zvednutým hledím“. Jako možnost poslední volby ještě před zvažováním CVK nebo intraoseálního vstupu je kanylace v. jugularis externa nebo v. axillaris.
 * Abychom mohli lépe posoudit, zda nechybujeme v rychlosti vpichu, nutno opakovaně trénovat optimální rychlost vpichu (5–6/37 mm) na nečisto! Stává se, že časem nám ideální rychlost „vypadne z ruky“ Je to pravděpodobné zejm. v situaci, kdy máme za sebou sérii neúspěšných pokusů v řadě, třeba i u několika pacientů. Zdánlivě chybí logika naší chyby, ale společným jmenovatelem je průnik do žíly s objevením se krve v konusu kapiláry, ale nemožností dále kanylu zavést („nejde“ nebo „boule“). Pravděpodobnost špatné rychlosti je pak velmi pravděpodobná!

'Velmi důležitým mementem je fakt, který se již nesčetněkrát potvrdil a je skutečně alfou a omegou všech kanylací: vždy kanylujeme žílu, jejíž lumen je dostatečně naplněno a zároveň podkoží dostatečně napnuto. Tato poznámka platí pro všechny typy žil, ale nejdůležitější je toto si uvědomit při kanylacích v. saphena, žil v oblasti hlavičky a novorozenců.' Toto je jistě nejdůležitější poznámka ke kanylacím, proto ji uvádím samostatně a zcela v závěru! ''

Abychom mohli lépe posoudit, zda nechybujeme v rychlosti vpichu, nutno opakovaně trénovat optimální rychlost vpichu (5– 6/37 mm) na nečisto!

U chroniků při kanylaci v kubitě naslepo je nutno již iniciálně nesledovat vstup kanyly pod kůži, ale hlídat si konus kapiláry a zdá se, že je možný i větší úhel vpichu.

Osvědčilo se mi i „ohnutí“ kanyly při zavádění do tenkých a povrchových žil… už před zaváděním (jen pokud mám antibiotickou clonu, nebo přísně sterilně), nebo při propíchnutí kůže, jemně zatlačím, mandrén ohnu vertikálněji cca 40° oproti původnímu horizontálnímu směru, nepropíchnu tak žílu skrz…

Postup „s otevřeným hledím“ neboli „přískokem vpřed“
Tuto techniku volíme tam, kde kanylujeme žíly tenké, uložené těsně pod povrchem nebo nad niveau, u novorozenců, dystrofiků nebo chroniků. Prostě všude tam, kde při použití klasického způsobu hrozí, že se nám krev v konusu kapiláry objeví až po projetí žíly.

Postup s „otevřeným hledím“ znamená, že při vpichu sledujeme hrot kanyly a hloubku vpichu volíme podle našeho odhadu o uložení žíly. Pohyb nesmí být příliš pomalý. Jehla kanylek Braun jen o 1–2 mm předbíhá plastovou kanylu, proto vedeme vpich, jako kdybychom do žíly chtěli dostat jen jehlu → častým neúspěchem je iniciálně příliš hluboký vpich nebo příliš hluboké další „přískoky“.

Při pokusu s otevřeným hledím vedeme vpich, jako kdybychom do žíly chtěli dostat jen jehlu → častým neúspěchem je iniciálně příliš hluboký vpich nebo příliš hluboké další „přískoky“.

V situaci, kdy po iniciálním vpichu se neobjeví kapka krve v konusu kapiláry, postupujeme dále metodou „přískoků vpřed“. Pokud je žíla dobře patrna, potom opět sledujeme hrot jehly a postupujeme o 2–3 mm vpřed, poté se zastavíme a zkontrolujeme, zda v konusu kapiláry není krev. Pokud se krev objeví, jehlu vytáhneme a standardně zasuneme kanylu. Pokud se krev neobjeví, postupujeme stejným postupem dále. Pokud jsme cestou žílu nepotkali = neobjevila se nám krev v konusu kapiláry, kanylku pomalu vytáhneme pod povrch kůže a zkusíme stejný postup trochu jiným směrem. U nejtenčích žil se může stát, že se krev v konusu kapiláry neobjeví. Pokud se domníváme, že by tomu tak mohlo být, je dobré zkusit vytáhnout mandrén – pokud se do kanyly nahrne krev, zkusíme kanylu s prostřikem zastrčit, pokud se krev v kanyle neobjeví, zasuneme mandrén zpět a pokračujeme dále.

Metodu „přískoků vpřed“ můžeme použít v situaci, kdy neindikujeme kanylaci klasickým způsobem, ale nevidíme lumen žíly. Potom se pohybujeme vpřed vždy o 2–3 mm, ale sledujeme jen konec kapiláry.

Nejčastější chyby při kanylaci

 * Vůbec nejčastější chybou je situace, kdy vedu vpich a kůže není dobře napnutá nebo lumen žíly není dobře patrné!!!
 * Pravděpodobně druhou nejčastější chybou je, že začnu kanylovat žílu, o které nejsem dostatečně přesvědčen, že je ideální (tenké žíly nebo žíly, kde není patrný směr jejich průběhu), aniž bych věnoval dostatek času a prohlédl všechny pacientovy dostupné žíly a vybral teprve poté tu nejlepší. (Typická je situace, kdy dítě neskutečně rozpíchám, aby konečný "úspěch" přinesla kanylace žíly s dobrým průběhem i průsvitem, které jsem si vůbec nevšiml!)
 * Příliš hluboký iniciální vpich nebo příliš dlouhé přískoky při metodě s otevřeným hledím.
 * Kanylace žil, které jsou průsvitem tak tenké, že je nelze vůbec technicky zakanylovat (nenechat se zmást zdánlivě dobrou tloušťkou žíly při jejím napětí).

Situace, kdy vedu vpich a kůže není dobře napnutá nebo lumen žíly není dobře patrné je vůbec nejčastější příčinou neúspěchu.

Komplikace

 * Celullitida,
 * flebitida,
 * arteficiální kanylace arterie,
 * paravenosní kolekce → riziko možného poškození tkání,
 * hematom,
 * trombóza, ev. embolizace části kanyly.

Všechny tyto komplikace jsou indikací k odstranění kanyly.

Pokud nejsou přítomny příznaky komplikací, můžeme kanylu ponechat in situ i déle, než běžně v literatuře uváděných 72 hodin.

Související články

 * Kanylace centrální žíly
 * Kanylace arterie

Externí odkazy

 * Video Kanylace periferní žíly

Zdroj

 * HAVRÁNEK, Jiří: Kanylace periferní žíly.