Venous access

Venous access is any method used to access the bloodstream through the veins, either to administer intravenous therapy (e.g. medication, fluid), parenteral nutrition, to obtain blood for analysis, or to provide an access point for blood-based treatments such as dialysis or apheresis. Access is most commonly achieved via the Seldinger technique, and guidance tools such as ultrasound and fluoroscopy can also be used to assist with visualizing access placement.

Methods

Peripheral

The most common form of venous access is a peripheral venous cannula which is generally inserted into veins of the hands, forearms, and occasionally feet.[1] Healthcare providers may use a number of different techniques in order to improve the chances of successful access. Some techniques include using a tourniquet, tapping over the vein, warming the area to dilate the vein, or using an ultrasound to directly visualize the target vein. Near-infrared illumination devices can also be used to help identify superficial veins that are not easily felt or seen with the naked eye. These devices emit infrared light which is absorbed by hemoglobin in the blood, allowing for easier visualization of the vasculature.[2]

Peripheral access is usually indicated when short-term access up to 7 days is needed. Complication rates from these peripheral access points increase quickly the longer they remain in place, and thus are routinely removed and replaced every 3–4 days if possible.[1][3][4]

Central

In some situations, venous access is obtained by inserting catheters into the large central veins of the body such as the internal jugular, subclavian, or femoral veins. This type of venous access is done with central venous catheters (CVCs), and is required in certain situations where peripheral access is inadequate. Such situations include, but are not limited to, the need for long-term venous access, administering of medications that can damage smaller veins (e.g. chemotherapy), measuring central venous pressure, or obtaining certain blood tests (specifically central venous oxygen saturation).[5][6] Types of CVCs include non-tunneled and tunneled catheters, PICC lines, and implanted ports.

Midline

Midline access is a type of peripheral venous access inserted into peripheral veins and that extends further than standard peripheral catheters but does not yet reach the large central veins of the thorax. They are used when intermediate-term access is needed or when administering medications that are highly irritating to smaller veins. However, their use is declining in favor of PICC lines which have the added benefit of more central access and longer potential dwell-times.[1][2][7]

In children

In children, the most common form of venous access is also peripheral access although the dwell time in children are much shorter than in adults, 1-4 days. Accessing veins in the legs in children can promote immobilization, but is used if there are no other way. In neonates, scalp veins can also be used if other peripheral veins are not accessible.[2] Umbilical veins are also an option in neonates, but is per definition a central access.

When accessing veins in children, certain other factors are considered such as their smaller caliber veins and anatomical variations. Gaining venous access in children can thus present a number of different challenges than in adults. For example, certain antiseptic cleaners are avoided because of they may irritate the skin of young children. Children also have thinner connective tissues than adults and thus some techniques used to illuminate veins may have a risk of causing burns.[2]

Complications

Most common complications with venous access are catheter related infections, thrombophlebitis and venous thrombosis. If having thrombophlebitis or thrombosis; pain when using the access is another complication. Peripheral venous access is least prone to thrombosis, followed by midline catheters and the centrally placed catheters. Central venous access is the most common reason for venous thrombosis in children.

Emergency situations

In emergency situations when peripheral access cannot be easily achieved, such as in arrest scenarios, intraosseus methods can be used to gain rapid access to the venous system. These methods usually involve inserting an access device into the tibia or femur bones in the legs, humerus in the upper arm, or sometimes the sternum in the chest.[2][8]

Venous cutdown can also be done to gain immediate emergency access to the venous system. Venous cutdown procedures most commonly target the great saphenous vein in the leg because it is superficial, easily accessible, and consistently in the same anatomical location. This procedure is used in certain populations such as critically ill patients or patients in hypovolemic shock or when less invasive methods such as peripheral catheters or CVCs have failed. However, in many cases the use of intraosseus access has replaced the need for venous cutdown procedures.[9][10]

References
  1. Cheung, Edward; Baerlocher, Mark O.; Asch, Murray; Myers, Andrew (May 2009). "Venous access: a practical review for 2009". Canadian Family Physician. 55 (5): 494–496. ISSN 1715-5258. PMC 2682308. PMID 19439704.
  2. Naik, Vibhavari M.; Mantha, S. Shyam Prasad; Rayani, Basanth Kumar (September 2019). "Vascular access in children". Indian Journal of Anaesthesia. 63 (9): 737–745. doi:10.4103/ija.IJA_489_19. ISSN 0019-5049. PMC 6761776. PMID 31571687.
  3. "Vascular Access Device (VAD) Selection and Procedures" (PDF).
  4. Sou, Vanno; McManus, Craig; Mifflin, Nicholas; Frost, Steven A.; Ale, Julie; Alexandrou, Evan (2017). "A clinical pathway for the management of difficult venous access". BMC Nursing. 16: 64. doi:10.1186/s12912-017-0261-z. ISSN 1472-6955. PMC 5693534. PMID 29176933.
  5. Principles and practice of hospital medicine. McKean, Sylvia C. New York: McGraw-Hill. 2012. ISBN 9780071603898. OCLC 721902323.CS1 maint: others (link)
  6. Ge, Xiaoli; Cavallazzi, Rodrigo; Li, Chunbo; Pan, Shu Ming; Wang, Ying Wei; Wang, Fei-Long (2012-03-14). "Central venous access sites for the prevention of venous thrombosis, stenosis and infection". The Cochrane Database of Systematic Reviews (3): CD004084. doi:10.1002/14651858.CD004084.pub3. ISSN 1469-493X. PMC 6516884. PMID 22419292.
  7. Horattas, Mark C.; Trupiano, John; Hopkins, Steve; Pasini, Debbie; Martino, Carl; Murty, Aparna (February 2001). "Changing concepts in long-term central venous access: Catheter selection and cost savings". American Journal of Infection Control. 29 (1): 32–40. doi:10.1067/mic.2001.111536. ISSN 0196-6553. PMID 11172316.
  8. Tobias, Joseph D.; Ross, Allison Kinder (2010-02-01). "Intraosseous infusions: a review for the anesthesiologist with a focus on pediatric use". Anesthesia and Analgesia. 110 (2): 391–401. doi:10.1213/ANE.0b013e3181c03c7f. ISSN 1526-7598. PMID 19897801.
  9. Lee, Mary M.; Loyd, Joshua W. (2019), "Saphenous Vein Cutdown", StatPearls, StatPearls Publishing, PMID 30422475, retrieved 2019-10-31
  10. Haas, Nikolaus A. (December 2004). "Clinical review: vascular access for fluid infusion in children". Critical Care (London, England). 8 (6): 478–484. doi:10.1186/cc2880. ISSN 1466-609X. PMC 1065040. PMID 15566619.
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