Continuing Education Activity

Peripheral intravenous lines are single-lumen, indwelling plastic conduits designed to deliver fluids, medications, and blood products directly into peripheral veins. Intravenous cannulations are the most frequently performed invasive procedure in acute healthcare settings, with over 1 billion insertions annually worldwide. Patients who may require peripheral intravenous access include those with dehydration, critical illness, need for rapid fluid resuscitation, electrolyte disturbances, or long-term medication therapy. Challenges to successful placement arise from difficult venous anatomy, patient comorbidities, or previous intravenous therapy, which may increase the likelihood of insertion failure or complications.

Clinical signs indicating the need for intravenous access include hemodynamic instability, inability to tolerate oral medications, or need for intravenous therapies. Proper insertion technique, site selection, and ongoing line maintenance are critical to reduce risks, such as infiltration, phlebitis, thrombosis, and infection. Failure to establish access can delay essential therapies, while inappropriate placement or management can result in local and systemic complications.

This activity for healthcare professionals is designed to sharpen learners' skills in identifying individuals requiring peripheral intravenous catheterization and performing the procedure proficiently. Participants will advance their mastery of indications, contraindications, techniques, and measures to mitigate potential complications associated with this procedure. Anatomical and landmark-based approaches will be emphasized to optimize access and minimize risks. Greater competence will empower clinicians to collaborate with interprofessional teams caring for patients requiring this intervention.

Objectives:

• Identify individuals with possible indications for peripheral intravenous line placement based on clinical presentation, risks, and benefits.
• Apply proper peripheral intravenous line placement techniques to achieve successful vascular access while minimizing patient discomfort and reducing the risk of complications.
• Develop systematic strategies to evaluate peripheral intravenous line patency, detect complications early, and maintain safe, effective vascular access.
• Collaborate with the interprofessional team to provide peripheral access safely and effectively and enhance patient outcomes.

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Introduction

Peripheral line placement, also referred to as "peripheral intravenous cannulation," involves the insertion of a single-lumen, indwelling plastic conduit through the skin into a peripheral vein. Such devices may be termed "peripheral intravenous lines," "cannulas," or "catheters," depending on regional nomenclature.

These conduits permit direct administration of fluids, medications, and blood products into the cardiovascular system, bypassing gastrointestinal or other absorptive barriers and allowing rapid delivery to target organs. Once properly inserted, a functioning line can remain in situ for several days, reducing the need for repeated venipuncture in patients requiring ongoing therapy. Peripheral line placement is the most frequently performed invasive procedure in acute healthcare settings, with up to 80% of hospitalized patients requiring intravenous access, and more than 1 billion lines utilized globally each year.[1][2]

This article emphasizes anatomical landmark–guided techniques for peripheral line placement. Lines may also be inserted under real-time ultrasound guidance, particularly when difficult access is anticipated or multiple cannulation attempts have been unsuccessful.[3]

Anatomy and Physiology

Peripheral venous cannulation may be successfully performed at various sites throughout the body. The nondominant upper extremity is commonly selected due to patient comfort, lower risk of line dislodgement, and decreased incidence of thrombosis or thrombophlebitis.

In the upper extremity, potential access sites begin distally with the metacarpal veins on the dorsum of the hand. These veins drain proximally via the dorsal venous arch, continuing as the cephalic and basilic veins in the forearm. Near the antecubital fossa, the median cubital and median antebrachial veins connect these vessels before they continue proximally up the arm. In the lower extremity, cannulation may begin with the dorsal venous plexus of the foot, which drains into the great and small saphenous veins of the leg. The scalp may provide an appropriate site in neonates or infants, particularly when attempts on the limbs have failed or are predicted to be unsuccessful. Frontal, occipital, superficial temporal, or posterior auricular veins may be used in these cases.[4]

Preferred veins are straight, distal, and unbranched, as venous valves are commonly located near branching points. A tourniquet may be applied proximally to engorge the vein when using a limb site. The vein should feel spongy and nonpulsatile on palpation. Veins that feel rigid on palpation are likely to be thrombosed. In contrast, pulsatility signifies arterial flow. Identification of suitable access sites may be more challenging in specific populations, including children and individuals who have obesity, are pregnant, possess darker skin tones, present with shock, or demonstrate vein changes from prior chemotherapy or intravenous drug use.[5]

Indications

The most common indication of this procedure is to enable the intravenous administration of medications and fluids. Lines are also frequently used for phlebotomy at the time of insertion, performed before any medication or fluid administration to prevent sample dilution or contamination.

Contraindications

Peripheral intravenous cannulation has no absolute contraindications. Meanwhile, relative contraindications include coagulopathy; local infection, burns, or compromised skin at the intended insertion site; and prior lymphatic nodal clearance, arteriovenous fistula formation, or deep venous thrombosis in the affected limb. Clinical judgment is required to weigh the benefits and risks of proceeding with line placement in these settings.

When an extended course of intravenous therapy is anticipated, another vascular access device, such as a peripherally inserted central catheter (PICC), may be more appropriate. These devices are more invasive and require specialist expertise to place but offer lower failure rates during prolonged use. Conventional peripheral lines may require frequent replacement in such scenarios.[6]

An ultrasound-guided technique may be warranted in time-critical cases where peripheral access is known to be difficult or multiple attempts have failed. The clinician may also need to consider alternative routes of drug administration, such as oral, intramuscular, intraosseous, or central venous access.

Equipment

The intravenous line consists of a hollow, plastic, tube-shaped catheter attached to a larger hub that remains above the skin. Most modern catheters are constructed from polyurethane, a material associated with lower thrombogenicity than older polyvinylchloride designs. The device is supplied preloaded over a hollow, laser-sharpened, beveled needle equipped with a transparent flashback chamber. This chamber permits visualization of blood entry during venous cannulation.

The hub is color-coded according to needle gauge, which corresponds to the catheter’s internal diameter and typically ranges from 14G to 24G, depending on patient age and clinical needs. Higher gauge numbers indicate narrower catheters. Catheter length varies among manufacturers.

Once the needle is withdrawn from the hub, a standard Luer-taper connector becomes accessible for attachment of a phlebotomy adapter, a needle-free injection port, or an intravenous fluid administration set. Some hubs also include a side port with a removable cap, enabling drug delivery without interrupting ongoing intravenous infusions.

So-called “safety lines” are newer intravenous catheters designed to reduce accidental needlestick injuries during placement, and their use has increased over the past decade.[7] These devices incorporate an active or passive mechanism that shields the needle once it is withdrawn from the cannula hub. Active systems require manual activation, typically a button that retracts the needle into a plastic sheath, whereas passive systems deploy a small protective shield automatically upon needle withdrawal.[8]

Peripheral vascular access also requires ancillary equipment, including antiseptic swabs or sponges, gauze, a needle-free injection port, a prepared flush of sterile normal saline, and a sterile transparent moisture-permeable dressing. Local anesthetic agents may be advantageous when larger cannulas are used or procedural distress must be minimized in sensitive populations, such as young children. Subcutaneous infiltration with a small volume of a local anesthetic (for example, 0.1 mL of 1% lidocaine) may be performed shortly before insertion, or a topical anesthetic ointment may be applied under an occlusive dressing for preprocedural analgesia.

Personnel

Peripheral line placement is commonly performed by a single operator. An assistant may be beneficial to calm anxious or distressed patients, particularly children, or to optimize patient positioning in cases of difficult vascular access.

Preparation

When peripheral lines are inserted for a specific procedure or treatment, placement should occur as close to the procedure time as possible to minimize the risk of line dislodgement. The operator must perform hand hygiene and don single-use treatment gloves. If a topical local anesthetic ointment has been applied, it should be removed prior to insertion. A sharps disposal container should be readily available.

A tourniquet is applied around the limb approximately 5 to 10 cm proximal to the intended site, tight enough to engorge the veins without obstructing arterial blood flow. Vein engorgement facilitates identification and successful cannulation. The area is then inspected and palpated to select an appropriate vein and subsequently cleaned with an antiseptic. When infiltrative anesthesia is used, the local anesthetic is injected near the vein with a narrow needle to raise a small subcutaneous weal at the intended puncture site, generally positioned slightly distal to the location where the vein will be pierced.

Technique or Treatment

The cannula should be held firmly in one hand, with the forefinger and thumb on either side of the hub (see Image. Techniques for Securing a Peripheral Intravenous Catheter During Insertion). If a side port is present, the forefinger may be curled around the port cap while the thumb rests on the end of the flashback chamber. The other hand is used to apply distal traction, stabilizing the vein and stretching the surrounding skin taut.

The needle is inserted at a shallow angle of less than 45°, advancing slowly toward the vein until a flash of blood appears in the chamber. If only a small drop of blood is visualized, the needle bevel may remain partially outside the vein. In this case, the line should be flattened slightly and advanced incrementally by 1 to 2 mm until adequate flow is observed. The cannula is then threaded over the needle until the hub rests at the skin surface, at which point a second flash of blood should appear within the catheter as it enters the vein.

The tourniquet is subsequently loosened or removed. Proximal pressure is applied over the vein and catheter to prevent blood loss while the needle is withdrawn and safely discarded into a sharps container. Blood samples may be collected at this stage using a syringe or phlebotomy adaptor, with temporary tourniquet reapplication to ensure adequate flow. The bung or intravenous administration set is then attached to the hub, and the cannula is secured to the skin with an appropriate dressing. Flow is confirmed with a saline flush or prepared intravenous fluid, observing for the absence of swelling or edema at the insertion site.

Different strategies have been proposed to enhance the success of peripheral line placement, particularly in challenging circumstances, although the supporting evidence varies. Techniques include gently ballotting or tapping the skin overlying the vein, followed by antiseptic preparation, and applying a warm compress or soaking the limb in warm water briefly before insertion. Optimizing operator ergonomics, including patient positioning and adequate ambient lighting, may also improve success. Topical application of glyceryl trinitrate in small aliquots has been suggested as an additional measure.

Peripheral venous cutdown may be considered in critically ill patients requiring emergency intravenous access when peripheral attempts have failed. This technique involves making a skin incision over a suitable peripheral vein, such as the median basilic vein in the arm or the long saphenous vein in the leg, and bluntly dissecting down to the vessel to allow direct cannulation. Peripheral venous cutdown was historically a mainstay of resuscitation. However, with the advent of alternative modalities, including ultrasound-guided central venous access via the Seldinger technique and intraosseous access, the use of this modality has declined and is uncommon in many well-resourced healthcare systems.[9]

Complications

Local complications of peripheral line placement include procedural failure, arterial or nerve injury, and hematoma or bleeding at the insertion site. Among successfully placed lines, up to 50% may experience some degree of failure before clinical discontinuation.[10] Accidental dislodgement is common but may be mitigated by using breakaway devices, which safely disconnect the cannula from the intravenous administration set if excessive tension is applied.[11]

Inadvertent arterial cannulation is more likely in children at specific sites, such as the antecubital fossa, and can have serious consequences if incompatible medications or fluids are administered.[12] Arterial puncture from inadvertent cannulation warrants prompt removal of the line with direct pressure applied to control bleeding.

Infiltration of intravenous therapy into surrounding tissues may result if the catheter migrates out of the vein, is incompletely threaded during insertion, or passes entirely through the vein. Phlebitis, or inflammation of the vein, is more likely with poor aseptic technique or prolonged intravenous therapy. Phlebitis can progress to local infection or cellulitis.

Catheter or vein occlusion may occur due to mechanical trauma, proximity to venous valves, or thrombosis at the catheter tip. Leaving an empty intravenous fluid administration set attached to the cannula, particularly if the limb is constricted by patient positioning or noninvasive blood pressure monitoring, can allow blood to overcome residual pressure in the line, leading to clot formation and occlusion. Scalp lines in neonates and infants carry an increased risk of dislodgement and extravasation.

Systemic complications directly resulting from peripheral line placement, such as anaphylaxis, are rare. Allergic reactions are more commonly related to medications or fluids administered through the catheter. Vasovagal syncope occurs more frequently in patients who are seated rather than lying down during insertion, have a previous history of fainting, or exhibit marked anxiety related to blood or needles.[13][14] Catheter fracture may occur, with a portion of the device shearing off and embolizing within the venous system, potentially necessitating retrieval by a vascular surgeon.[15]

Clinical Significance

Peripheral intravenous lines are the primary method for delivering intravenous therapy in acute healthcare settings. Placement of these lines is a core competency for many healthcare professionals and may also be performed by trained technicians or assistants, depending on local protocols and the scope of practice.

According to the Hagen-Poiseuille equation, which describes flow dynamics for fluids undergoing fully developed laminar flow, the rate of flow through a cylindrical tube is directly proportional to the pressure gradient applied across the tube and inversely proportional to its length. However, flow is proportional to the 4th power of the internal radius, making this parameter the most critical determinant of flow rate. Consequently, increasing the catheter caliber has a far greater impact on maximum achievable flow than reducing line length. Therefore, a wide, short peripheral line can deliver substantially higher flow rates than more complex vascular access devices, such as central venous catheters.

Catheter diameter is expressed using either the Birmingham gauge system or the French system. In the gauge system, a lower number corresponds to a larger diameter. Peripheral intravenous lines are commonly available in sizes ranging from 14G to 26G, with 14G being the widest and capable of the highest potential flow rates. However, sustained high flow rates can markedly increase shear stress on the venous endothelium, potentially causing endothelial dysfunction and earlier peripheral line failure.[16]

The French system defines catheter size based on the outer diameter in millimeters multiplied by 3. For example, a catheter with a 6-mm outer diameter corresponds to an 18F catheter. In clinical practice, the French system is not applied to peripheral intravenous lines and is primarily reserved for larger medical devices or catheters designed for specialized purposes.

Enhancing Healthcare Team Outcomes

Optimal outcomes in intravenous therapy rely on an interprofessional team approach, typically involving nurses and phlebotomy technologists under the supervision of managing physicians. Success depends on prompt line placement when indicated, ongoing monitoring of line function, regular assessment of the continued need for venous access, removal of lines when no longer clinically necessary, and early intervention if complications are suspected.[17] Implementation of peripheral intravenous line care bundles can help standardize practice and reduce complication rates.[18]

Historically, some healthcare facilities mandated routine replacement of peripheral intravenous lines after a set period, such as 48 to 72 hours, to mitigate complications. However, a 2018 systematic review and meta-analysis found no evidence that scheduled line replacement reduces the incidence of thrombophlebitis, catheter-related bloodstream infections, pain, or mortality, although it may decrease catheter occlusion. Routine replacement may also increase healthcare costs.[19] European guidelines from 2021 similarly concluded that short (<6 cm) lines should not be removed solely based on time elapsed.[20] An international expert consensus in 2023 recommended peripheral intravenous lines for short-term therapy (up to 7 days), with dwell times generally kept under 4 days to minimize phlebitis and infiltration.

The benefit of safety lines compared with standard intravenous lines remains uncertain. Users report a perceived lower risk of needlestick injury when using safety lines. However, these devices are more expensive and may complicate insertion due to slower flashback, increased friction during cannula advancement, and greater difficulty threading the line into the vein.[21] Activation of the mechanism may also increase the risk of blood splatter.[22] A 2012 review found that active safety lines were associated with higher rates of environmental blood contamination, whereas passive safety lines were not, and no evidence demonstrated a reduced incidence of sharps injuries with either type.

Traditionally, intravenous placement has been avoided in the ipsilateral arm of patients who have undergone breast surgery, particularly if the lymphatic system was disrupted. A 2021 retrospective review of 3,724 patients with prior breast cancer surgery found no complications associated with intravenous cannulation in the ipsilateral arm.[23] Current recommendations from the American Society of Breast Surgeons indicate that use of the ipsilateral arm for intravenous access is not contraindicated.[24]

Review Questions

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References

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Naranjo J, Portner ER, Jakub JW, Cheville AL, Nuttall GA. Ipsilateral Intravenous Catheter Placement in Breast Cancer Surgery Patients. Anesth Analg. 2021 Sep 01;133(3):707-712. [PubMed: 34043309]

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McLaughlin SA, DeSnyder SM, Klimberg S, Alatriste M, Boccardo F, Smith ML, Staley AC, Thiruchelvam PTR, Hutchison NA, Mendez J, MacNeill F, Vicini F, Rockson SG, Feldman SM. Considerations for Clinicians in the Diagnosis, Prevention, and Treatment of Breast Cancer-Related Lymphedema, Recommendations from an Expert Panel: Part 2: Preventive and Therapeutic Options. Ann Surg Oncol. 2017 Oct;24(10):2827-2835. [PubMed: 28766218]

Disclosure: Gabriel Beecham declares no relevant financial relationships with ineligible companies.

Disclosure: Ankit Agarwal declares no relevant financial relationships with ineligible companies.

Disclosure: Gary Tackling declares no relevant financial relationships with ineligible companies.