Peripheral venous access in adults

INTRODUCTION — Peripheral venous cannulation, among the most common medical procedures, has revolutionized the practice of medicine. Peripheral intravenous (IV) catheters allow for the safe infusion of medications, hydration fluids, blood products, and nutritional supplements. First-time success rate for peripheral IV placement ranges from 65 to 86 percent [1].

This topic will discuss the indications, contraindications, performance, and complications of peripheral venous catheter placement without the use of ultrasound guidance. Emergency vascular access in children, intravenous device routine care and risk factors for infection, peripheral venous catheter placement under ultrasound guidance, and central venous catheter placement are reviewed separately.

●(See "Vascular (venous) access for pediatric resuscitation and other pediatric emergencies".)

●(See "Routine care and maintenance of intravenous devices".)

●(See "Intravascular catheter-related infection: Epidemiology, pathogenesis, and microbiology".)

●(See "Basic principles of ultrasound-guided venous access".)

●(See "Central venous access: acute and emergency access in adults".)

INDICATIONS AND CONTRAINDICATIONS

Indications for venous access — Most often, intravenous (IV) access is obtained to provide therapies that cannot be administered or are less effective if given by alternative routes. As examples, IV hydration and nutritional support can be given to a patient with severe vomiting or abdominal pain from a surgical condition. Certain medications are more effective when given IV due to rapid onset or increased bioavailability. Some clinical situations, such as cardiac arrest, require treatment using IV medications; blood products must be given IV. In some instances, IV catheters are left in place when medications are given intermittently over a longer period (eg, long-term antibiotic therapy) or in case of a potential emergency.

Indications for peripheral versus central venous access — The decision to obtain peripheral rather than central venous access depends upon clinical circumstances. In general, peripheral catheters are preferred when IV access is required for shorter periods, when direct access to the central circulation is unnecessary, and when smaller gauge catheters suffice. Peripheral access is generally safer, easier to obtain, and less painful than central access. In patients taking anticoagulants, peripheral access allows for direct compression of puncture sites and fewer hematoma-related complications compared with the sites used for central venous catheters.

Central venous catheters are often preferred in patients receiving sclerosing medications that can damage peripheral veins or being treated with vasopressors, which can cause injury if extravasated. Central venous access may also be preferable in patients with severe volume depletion or in whom peripheral venous catheter placement has a low likelihood of success (ie, frequent users of illicit IV drugs). (See "Central venous access in adults: General principles", section on 'Indications'.)

In patients with septic shock, recent guidelines recommend starting vasopressors via peripheral access rather than waiting for central venous access to be obtained [2]. Restoring mean arterial pressure is prioritized over the risk of tissue injury from vasopressor extravasation. Local tissue injury is unlikely to occur from vasopressors given through a peripheral catheter proximal to or in the antecubital fossa, especially if for a short duration (six hours or less) [3]. If extravasation occurs, the catheter should be aspirated while it is removed and phentolamine injected subcutaneously around the extravasation area; serious events are uncommon [3,4]. (See 'Complications' below and "Use of vasopressors and inotropes", section on 'Local effects' and "Extravasation injury from cytotoxic and other noncytotoxic vesicants in adults", section on 'Initial measures' and "Extravasation injury from cytotoxic and other noncytotoxic vesicants in adults", section on 'Vasoactive drugs'.)

Contraindications — There are few contraindications to the placement of peripheral venous catheters. Most concern problems with cannulation at a specific site. The sole absolute contraindication is when appropriate therapy can be provided by a less invasive route (eg, orally). Guidelines about appropriate sites for the placement of peripheral venous catheters are described separately. (See 'Site selection' below.)

Some clinicians consider the use of a limb with a significant motor and/or sensory deficit for placement of a peripheral IV catheter to be relatively contraindicated. Anecdotal evidence suggests that paralyzed extremities and limbs with significant weakness may be at slightly increased risk of developing deep vein thrombosis. However, there is no clear evidence that routine placement of a standard length peripheral IV catheter increases this baseline risk, especially in upper extremities [5,6]. Placement of a peripheral IV catheter in a limb with a significant sensory deficit may delay detection of fluid or medication infiltration if the patient is unable to feel the discomfort caused by such infiltration. In general, we think that a limb with a significant motor or sensory deficit may be used safely for temporary placement of a peripheral IV catheter, provided the limb is monitored closely, until a preferable site for venous access can be found.

ANTICIPATING DIFFICULT IV ACCESS — Difficult peripheral intravenous (IV) catheter placement occurs in 8 to 23 percent of cases [7,8]. Factors associated with difficult IV access include the following [7-13]:

●A history of difficult IV access

●Non-visible venous network

●History of diabetes

●History of IV drug use

●History of sickle cell disease

●History of cancer or chemotherapy treatment

●Female sex

●Extremes of age

●Dark skin tones

●Underweight or obese body habitus

●Vein being cannulated has dilated diameter <3 mm

The adult difficult IV access (A-DIVA) score (table 1) can be used to predict failed first attempt rate [14]. In a patient with anticipated difficult IV access, the most experienced clinician should attempt placement and utilize IV placement aids and/or ultrasound guidance. For example, emergency department technicians with five or more years of experience were more likely to successfully place catheters on the first attempt in children with anticipated difficult IV access [15].

The role of point-of-care real-time ultrasound guidance in patients with anticipated difficult IV access or failed attempts is discussed below. (See 'Role of ultrasound guidance' below.)

When it is critical to obtain IV access and attempts are not rapidly successful (especially if point-of-care ultrasound is not available), alternative approaches include intraosseous access and central venous catheters. (See "Intraosseous infusion" and "Central venous access: acute and emergency access in adults".)

MATERIALS

Equipment — Necessary materials for obtaining peripheral venous access include:

●Peripheral venous catheters of appropriate size

●Connective tubing and intravenous (IV) fluid

●Skin preparation materials (eg, chlorhexidine)

●Dressings

●Tape or a commercial device to secure the catheter

●Clean gloves and eye protection

If fluid administration is not required and the catheter is placed for intermittent therapy or anticipated need, a cap is placed atop the catheter. In such cases, a small syringe filled with a flushing solution (eg, isotonic saline) is required to ensure the catheter's patency.

Other materials that may be needed when obtaining peripheral venous access include a topical anesthetic to minimize the pain of venipuncture, fluid warmers, and pressure infusers. If a catheter is placed over a joint, a splint may help to reduce movement and decrease the risk of dislodging the catheter.

Catheters — IV catheters in common use today are pliable plastic tubes with an inner needle obturator (over-the-needle catheters) (picture 1) [16]. To reduce the risk of injury, the needles in most catheters in current use can be retracted into a needle guard by pushing a button on the flashback chamber after the catheter is inserted [16]. Steel needles, such as butterfly needles, may be appropriate for blood draws, but should not be used for prolonged IV therapy due to the risk of vein injury and extravasation of fluids or medications [17]. The risk of phlebitis and infection are discussed separately. (See "Catheter-related upper extremity venous thrombosis in adults", section on 'Phlebitis' and "Intravascular catheter-related infection: Epidemiology, pathogenesis, and microbiology", section on 'Risk factors'.)

●Gauge selection – The smallest appropriate needle size should be used, as smaller sizes cause less trauma and phlebitis [18]. Peripheral catheters range in gauges from 24 (smaller) to 14 (larger). Twenty-two- to 20-gauge catheters are typically used for medication administration or infusion of moderate volumes of fluid. Larger catheter sizes are indicated when rapid infusion of a large volume of fluid is anticipated. Flow rates through various sizes of IV catheters are listed in the table (table 2) [19].

An IV catheter with the largest radius and shortest length allows for the most rapid infusion [19]. Flow rates through peripheral IV catheters follow Poiseuille's law (V = ∏ p r⁴ / 8 ή l), which states that flow is directly related to the pressure driving the fluid and to the internal radius of the catheter raised to the fourth power, and inversely related to the length of the catheter and to the viscosity of the fluid. While statistical differences in flow rates have been reported across various brands of catheters, there do not appear to be clinically significant differences. Disparities between the slowest and fastest flow rates among different brands for 20-, 22-, and 24-gauge IV catheters were 6.6, 5.4, and 7.7 mL/min, respectively [20].

When transfusing blood, it had been thought that larger-bore IV catheters (20- to 18-gauge) were required to prevent hemolysis of red blood cells, but studies have not found this to be necessary. Infusion of red blood cells with IV catheter sizes as small as 24 gauge, even when performed with pressure infusers up to 300 mmHg, does not appear to cause hemolysis or any other adverse effects [21-24].

●Length selection – Catheters range in length from 2 to 3 cm (0.75 to 1.25 inches). Longer catheters (5 to 15 cm; 2 to 6 inches) may be beneficial for placement proximal to the antecubital fossa (typically under ultrasound guidance) by reducing the risk of dislodgement when the patient moves [25]. Long-term catheter functioning is directly related to the length of the catheter residing in the vein. For example, a study of 113 patients with ultrasound-guided peripheral IV placement found that all catheters failed (median time to failure 15.6 hours) if <30 percent of the catheter was in the vein compared with no catheter failures when ≥65 percent was in the vein [26].

SITE SELECTION

General guidance, risks, and site-specific contraindications — Many sites can be used for peripheral intravenous (IV) access, and they vary in their ease of cannulation and potential risks. Site selection varies according to clinical circumstances, expected duration of treatment, and the condition of the extremities.

In general, distal extremity sites should be used first, saving more proximal sites for subsequent cannulation, if needed. Placing an IV in a vein distal to a site that was previously punctured can lead to extravasation of fluids and hematoma formation. Larger veins are generally more easily cannulated and are preferable to smaller veins in the same region. Veins of the upper extremity are preferred due to the increased risk of thrombosis and thrombophlebitis with venous cannulation of the lower extremities [17,27,28]. Whenever possible, avoid using the dominant upper extremity.

Sites over joints (eg, antecubital fossa) should be avoided if possible due to the increased risk of catheter dislodgement and kinking, and the need to then immobilize the joint to reduce these risks. Peripheral IV catheters used for trauma resuscitation are an exception to this rule and are routinely placed in the larger veins of the antecubital fossa. (See "Initial management of trauma in adults", section on 'Circulation'.)

Contraindications to the use of a particular extremity include the presence of an arteriovenous fistula (catheter can alter venous blood flow or damage the fistula) [17]. Venous catheter placement should be avoided at a site that may interfere with an anticipated procedure (eg, an injured extremity that requires surgery). A history of mastectomy or lymph node dissection is no longer considered a contraindication to tourniquet use or venipuncture in the ipsilateral arm, provided lymphedema is not present. (See "Breast cancer-associated lymphedema".)

Veins that are firm to palpation may be sclerosed (eg, from IV drug abuse) and should be avoided as should veins with evidence of phlebitis or thrombosis. Venous puncture at sites where catheter placement was recently attempted should also be avoided, especially if a hematoma formed (ie, vein was "blown") following the previous attempt. (See "Superficial vein thrombosis and phlebitis of the lower extremity veins", section on 'Clinical presentations'.)

Placement of an IV through infected tissue is not advised due to the risk of introducing a systemic infection. In addition, peripheral IV catheters should not be placed through burned tissue or in extremities with massive edema.

Anatomy and vein selection — The veins of the dorsum of the hand are often the most accessible sites for peripheral cannulation (figure 1 and figure 2). As an example, the dorsal metacarpal veins are usually visible and palpable and make good sites for IV catheter placement [17]. These veins merge into the dorsal venous network (or arch) and then form the cephalic vein, which runs along the lateral distal forearm. The cephalic vein is usually visible and palpable and therefore another good site for cannulation [29]. The volar forearm also contains several veins that can be cannulated, including the median antebrachial veins [30].

The antecubital fossa, though not a primary choice for nonemergent IV access, contains several accessible veins, including the cephalic, median cubital, and basilic [30]. These veins are usually large and easily cannulated and provide a useful option when emergent IV access is needed. Veins in the proximal arm are more safely cannulated using ultrasound guidance. They include the more proximal portions of the basilic, cephalic, and brachial veins. If catheter placement is attempted in these proximal veins without ultrasound guidance, there is an increased risk of arterial puncture and nerve injury [31]. (See "Basic principles of ultrasound-guided venous access".)

In addition to the arm, leg and neck veins can be used to obtain peripheral IV access. The external jugular vein, which drains into the subclavian, is a large vein in the neck that is easily cannulated, even in patients with severe volume depletion or otherwise poor extremity access (figure 3) [32]. Placing the patient's bed in a head-down (ie, Trendelenburg) position or having them perform a Valsalva maneuver often enlarges the vein making cannulation easier. When inserting the catheter, avoid the valves in the external jugular vein, which can impair function [33]. (See 'Vein dilation' below.)

Veins of the leg, including the greater saphenous vein at the level of the medial malleolus and the dorsal metatarsal veins on the dorsum of the foot, are often accessible [34]. However, lower extremity sites should be used only if veins in the arm cannot be cannulated (figure 4). (See 'General guidance, risks, and site-specific contraindications' above.)

PREPARATION

Consent — Implied (presumed) consent is felt adequate for a procedure such as placement of a peripheral venous catheter where the risks and benefits are common knowledge to "persons of average intelligence" [35]. For intravenous (IV) catheter placement, consent can be assumed if the patient extends their arm for the procedure to be performed [36]. Some patients may be apprehensive about IV placement and in nonemergent cases, it is important to take some time to explain the reason for venous catheterization, risks and benefits, alternatives, expected duration of therapy, and the pain involved, and to allow the patient an opportunity to ask questions.

Obtaining IV access in uncooperative patients is challenging. It is important to determine why the patient will not or cannot cooperate. If the patient lacks the capacity to make reasoned medical decisions and has a potentially life or limb-threatening condition requiring urgent intervention, the use of restraints may be necessary. Chemical restraint is preferred, but temporary use of physical restraints may be required. (See "Assessment and emergency management of the acutely agitated or violent adult".)

If the patient is alert and has capacity but will not cooperate due to fear or anxiety, provide reassurance. Administration of a short-acting anxiolytic (eg, midazolam) prior to the procedure may be beneficial, as may allowing a parent, family member, or friend to help comfort the patient.

Basic preparations — Keep the patient warm and relaxed; both excessive cold and anxiety stimulate the sympathetic nervous system and can cause vasoconstriction of superficial vessels, thus making cannulation more difficult [37]. Patients who are excessively anxious may benefit from a small dose of a short-acting anxiolytic (eg, midazolam) prior to the procedure.

Excessive hair around catheter sites may be clipped to ease cannulation and improve dressing adherence [17]. Do not shave hair because this increases the risk of infection [16]. If a topical anesthetic is used, allow sufficient time for it to take effect. If possible, use the patient's nondominant extremity to reduce inconvenience and the effect of extravasation, should it occur.

The practitioner placing the IV and the patient should both be comfortable throughout the procedure. If possible, place patients in a supine position to avoid lightheadedness from pain or the sight of blood. Place the extremity with the venipuncture site on a stable surface below heart level to allow gravity to enhance venous dilation [38].

Prevention of infection — Before venipuncture is attempted, take appropriate steps to protect the patient and healthcare worker from infection. Wash your hands, and wear clean gloves and protective eye wear. Do not touch the puncture site after it has been cleaned with an appropriate solution (chlorhexidine). If there is a contraindication to chlorhexidine, tincture of iodine, an iodophor, or 70 percent alcohol can be used as alternatives. Prevention of infection associated with IV catheters, including cleaning agents and sterile technique, is discussed separately. (See "Routine care and maintenance of intravenous devices", section on 'Universal care strategies'.)

Vein dilation — Multiple methods for enhancing venous dilation to facilitate cannulation have been described [39]. Placing the anticipated cannulation site below the level of the heart uses gravity to reduce venous return, which causes blood to pool and veins to distend [40,41]. Lightly tapping or gently stroking the vein along its length in a proximal to distal direction causes venous distension [42,43]. Another simple, effective way to dilate veins consists of having the patient alternately clench and relax their fist [40].

Elevating skin temperatures to 39 to 42°C at the cannulation site causes venous dilation. This can be accomplished by placing the site in warm water or by applying a warm compress (eg, warm moist cloths, warming packs, heated carbon fiber mitts) [40,41,44-46].

Proximal compression, most often using a thin rubber tourniquet placed 5 to 10 cm proximal to the anticipated venipuncture site, impedes venous return and enhances venous dilation [40]. Tourniquet pressures should be greater than venous pressure, but less than arterial pressure to allow arterial inflow [40,44]. Other devices similar to tourniquets may be used, such as blood pressure cuffs and Esmarch bandages. If a blood pressure cuff is used, inflate it no higher than the diastolic blood pressure [47-49]. Avoid excessive pressure and prolonged application of the tourniquet to reduce the risk of vein injury and hematoma formation, especially in the elderly [50].

An Esmarch bandage is similar to the rubber tourniquets commonly used, but is 7.5 to 25 cm (3 to 10 inches) in width, and each roll is several hundred centimeters long. The Esmarch bandage is placed at the proximal end of the involved limb, and the limb is then wrapped circumferentially in a proximal to distal direction [51]. This squeezes blood from the proximal to the distal end of the limb, thereby dilating the veins.

Nitroglycerin ointment applied to the venipuncture site and left for two minutes causes venous dilation and does not appear to cause deleterious changes in blood pressure, even in hypotensive patients [52].

For the placement of larger IV catheters, a technique for dilating veins similar to Bier block regional anesthesia has been described [53]. After a small gauge IV catheter is placed, usually in the hand, the tourniquet is left in place. A volume of isotonic crystalloid (60 to 300 mL) is then infused. This fluid distends the surrounding collateral veins, allowing for placement of a larger gauge catheter.

Tools for locating veins — When no veins are readily visible or palpable, any of several transillumination devices can be used to locate veins for cannulation. One such device uses infrared light, which reflects off tissue surrounding the veins, but not the vein itself (eg, The VeinViewer, Luminetx, Memphis, Tennessee) [54]. Other devices use a light frequency that causes deoxygenated venous blood to appear darker than surrounding tissues (eg, Veinlite LED, TransLite, Sugarland, Texas) [54]. Handheld Doppler can be used to identify veins larger than 2 mm by identifying a venous signal [55].

Point-of-care ultrasound can be used to localize peripheral veins for cannulation and is particularly helpful to find deep peripheral veins that cannot be seen or palpated [56,57]. Ultrasound can identify the location, depth, and diameter of the vein prior to cannulation (ie, static method). Preferably, the entire cannulation can be performed under real-time ultrasound guidance (ie, dynamic method), during which the needle is visualized entering the vein and preventing potential injury to surrounding structures.  

Analgesia — Venipuncture is a painful procedure, but analgesia is not routinely provided outside the operating theater [58]. Nevertheless, topical and subcutaneous anesthetics reduce the pain and anxiety associated with IV catheter insertion, and they should be used whenever possible. Multiple methods are available for providing analgesia prior to venipuncture, including intradermal injection, topical medication, and technologies such as iontophoresis. A thorough discussion of topical anesthetics is found separately; a brief description of selected analgesic techniques for peripheral venous cannulation is provided here. (See "Clinical use of topical anesthetics in children".)

Intradermally injected local anesthetics are the traditional method of anesthetizing a puncture site. One percent buffered lidocaine injected subcutaneously provides rapid anesthesia and does not appear to decrease successful catheter placement [59]. This method reduces the pain from venipuncture, but involves a separate injection, which itself can cause pain, anxiety, and may distort puncture site anatomy [60-63]. Avoid intradermal anesthetics that contain epinephrine, which can cause the vein to constrict [64].

A number of topical anesthetics can be used to reduce the pain of venipuncture:

●EMLA, the eutectic mixture of lidocaine and prilocaine, reduces pain but requires approximately one hour to achieve peak effect. If used, 1 to 2 g should be applied per 10 cm² of skin and then covered with an occlusive dressing. EMLA is generally safe, but can cause methemoglobinemia with prolonged use or in those who are predisposed. (See "Clinical use of topical anesthetics in children", section on 'Lidocaine-prilocaine'.)

●LMX (formerly ELA-max) is a topical preparation of lidocaine encapsulated in liposomes, which are spherical, microscopic, phospholipid-based carriers that promote passage of the anesthetic through intact skin. LMX appears to have similar efficacy to EMLA in preventing pain from venipuncture, but takes only 30 minutes to exert its effect. Dosing is similar to EMLA: apply 1 to 2 g per 10 cm² of skin. (See "Clinical use of topical anesthetics in children", section on 'Liposomal lidocaine'.)

●Tetracaine, an ester anesthetic, can be applied as a 4 percent cream, a 5 percent gel (Amethocaine), or a 5 percent liposomal encapsulated cream (LET). Its efficacy and time of onset are similar to EMLA.

●Vapocoolant sprays act by cooling the skin surface immediately prior to IV placement. Spraying time is a key factor that determines performance and depends on individual site, blood flow, skin fat content, and other factors.  

Each method above has advantages and disadvantages, but all seem to provide similar degrees of anesthesia [65]. If time allows, topical agents are a good approach, but they may require 30 to 60 minutes to achieve maximum effect.

Iontophoresis, the application of a small electrical current to move ionized lidocaine through intact skin, has been used to provide local analgesia. Iontophoresis provides pain relief from venipuncture within 10 to 20 minutes. The technique can cause minor skin irritation and blistering. Similarly, sonophoresis, the use of low frequency ultrasound to facilitate skin penetration of a local anesthetic, has been shown to be fast (15 to 20 seconds of ultrasound time followed by five minutes of local anesthetic application) and effective in reducing pain from venipuncture [66,67]. A disadvantage of such techniques is the need for relatively expensive equipment.

Researchers have assessed the use of a single pulse of an erbium: yttrium-aluminum-garnet laser to remove the stratum corneum, thereby improving the penetration of local anesthetic. While the technique was found to reduce the pain of IV cannulation in volunteers within minutes, the cost of the laser device is prohibitive (approximately USD $2000) [68].

CATHETER INSERTION

Role of ultrasound guidance — We recommend using point-of-care real-time ultrasound guidance for peripheral intravenous (IV) catheter placement when difficulty is anticipated or after two failed attempts at the landmark technique [56,57,69-75]. The equipment (eg, ultrasound machine, longer catheters) must be available, the operator should have proficiency in real-time ultrasound guidance, and the patient's clinical status has to allow for the attempt. Anticipated difficulty can be determined by clinical judgement or an elevated A-DIVA score (table 1).  

A meta-analysis of 16 trials and 2267 patients compared ultrasound guidance versus the landmark technique for peripheral IV cannulation [57]. In patients who had difficult IV access (10 trials, 815 patients), ultrasound guidance improved the first-pass success rate (54 versus 36 percent, RR 1.5, 95% CI 1.15-1.95) and overall success rate (81 versus 56 percent, RR 1.4, 95% CI 1.10-1.77). There was no difference in pain or overall complications, but ultrasound guidance did increase the time to first-pass cannulation by two minutes. In patients with moderately difficult IV access (one trial, 401 patients), ultrasound guidance improved the first-pass success rate (81 versus 71 percent, RR 1.14, 95% CI 1.02-1.27). In patients with easy IV access (one trial, 596 patients), ultrasound guidance decreased the first-pass success rate (86 versus 97 percent, RR 0.89, 95% CI 0.85-0.94). The definition of difficult, moderately difficult, and easy cannulation varied between studies and typically included failed access by landmark approach, no apparent or palpable veins, and history of difficult cannulation.  

The real-time ultrasound guided peripheral IV placement technique is described in detail separately. (See "Basic principles of ultrasound-guided venous access", section on 'Ultrasound evaluation of vessels'.)

Landmark percutaneous technique — Once an appropriate site is selected, use the following technique to place the catheter:

●Place a tourniquet proximal to the intended site (picture 2).

●Cleanse the skin, being careful not to contaminate the puncture site after the skin is cleansed. A local anesthetic may be injected (picture 3).

●Hold the area steady with the nondominant hand, and use the thumb to pull gently on the vein. This reduces movement of the vein when inserting the needle. Avoid applying excessive pressure, which will collapse the vein.

●Hold the catheter in the dominant hand between the thumb and forefinger with the bevel facing upwards (picture 4).

●Approach the vein with the needle at a low angle, generally about 10 to 30 degrees from the skin surface. Puncture the skin, and enter the vein using a slow, smooth, continuous movement. A flash of blood in the flash back chamber of the catheter indicates that the needle has entered the vein.

●Advance the catheter another 1 to 2 mm to ensure that the catheter tip, which sits back slightly from the needle lumen, lies completely within the vein (picture 5).

●Place the tip of the dominant index finger against the small tab that extends up from the top of the hub of the catheter. Advance the catheter into the vein by extending the dominant index finger, thereby exerting pressure against the small tab with the fingertip. Maintain slight traction on the vein with the nondominant hand to prevent vein movement while the catheter advances. If the catheter is within the vessel lumen, it should advance easily and relatively painlessly (picture 6).

●If you cannot advance the catheter, it has either been advanced too far through the posterior wall of the vein, or the needle entered the vein but the catheter did not. If you suspect the former situation, withdraw the needle slightly until you see a good blood flash in the hub, and then try advancing the catheter. If you suspect the latter situation, advance the needle slightly, and then try to advance the catheter. In many cases, you must abort the attempt at cannulation if these problems arise, and try a different site, proximal to the first if the same extremity is used.

●Occasionally, the catheter is in the lumen of the vein but cannot be advanced because it lies against a valve or tortuous portion of the vein. If you suspect this, attach a syringe filled with isotonic saline to the catheter, and gently infuse fluid through the catheter while slowly advancing it. This problem can often be avoided by using relatively straight veins and by avoiding valves which are often visible as small, circumscribed bulges in the vein.

●If the intravenous (IV) catheter is appropriately placed, venous blood will flow steadily from the catheter, and no swelling will occur at the puncture site. Once the catheter has been inserted, push the button on the needle guard to allow the needle to be retracted and to prevent inadvertent needle stick injuries. Remove the tourniquet, secure the catheter, and attach the appropriate IV set up. If correctly placed, medicine or fluids should infuse easily, without pain or swelling at the catheter site (picture 7).

●If swelling occurs and extravenous placement is suspected, remove the catheter, and apply pressure at the puncture site to reduce hematoma formation; then place a dressing over the puncture site.

●Inadvertent arterial catheter placement usually causes a pulsatile flow of bright red blood and produces an arterial wave form when a transducer is attached. If this occurs, remove the catheter and apply continuous pressure at the puncture site for approximately 10 minutes.

●When the procedure is completed, place all sharp objects in the proper container, and dispose of other materials appropriately (picture 8).

POST-PLACEMENT CARE

Securing the catheter — Once the catheter is placed, secure it well to avoid dislodgement, which can cause extravasation of potentially harmful intravenous (IV) fluids and medications. In addition, movement of a poorly secured catheter may increase the risk of thrombophlebitis [76]. If the IV catheter must be placed over a joint or in a dominant hand, it is often helpful to place a splint. Selection of an appropriate site for catheter placement is discussed above. (See 'Site selection' above.)

Peripheral catheters can be secured with tape, prefabricated adhesive dressings (eg, Opsite, Smith and Nephew, United Kingdom; Tegaderm, 3M, St. Paul, Minnesota), suture, or specific IV securing devices. Transparent dressings are widely used; they are more breathable, allow earlier detection of local signs of inflammation, and improve nursing workflow. If the patient is diaphoretic or if the site is bleeding or oozing, a gauze dressing should be used. An unblinded randomized trial found that application of a drop of skin adhesive to the skin insertion site, and a drop under the catheter hub after insertion, followed by a standard tape and polyurethane dressing, resulted in lower rates of catheter failure (eg, dislodgement) at 48 hours, without significant adverse effects [77]. The relative advantages and disadvantages of methods for securing an IV catheter are discussed separately. (See "Routine care and maintenance of intravenous devices", section on 'Dressing and securement'.)

Maintaining patency — Peripheral IV catheters placed for intermittent therapy (INT) require occasional flushing to keep them patent. This is not a concern when catheters are used for continuous infusions. Previously, dilute heparin solutions were used to flush catheters, thus the term "heparin lock." Multiple studies have found that periodic flushing with isotonic saline is equally effective in maintaining the patency of catheters used for INT, while avoiding heparin-related complications [78-82]. No studies address the issue of how best to flush peripheral catheters with saline, but common practice is to use 2 to 10 mL of isotonic saline after any IV medication is given or every 4 to 12 hours [83].

Monitoring — After an IV has been successfully placed, clinicians should periodically reassess the catheter to verify proper placement and patency. Examine the site carefully if any redness, edema, pain, tenderness, or problems infusing develop. Ultrasound can be used to verify the catheter's position.

Extravasation of fluid usually manifests as swelling and pain at the site and slow infusion rates. If IV fluids no longer infuse via gravity and the catheter cannot be flushed easily, a clot may have formed within the catheter. Do not flush the catheter forcefully because this can dislodge a clot into the circulation and should not be done.

COMPLICATIONS — When performed properly, peripheral intravenous (IV) placement is a safe procedure with little serious risk. Nevertheless, a number of potential complications have been described. Among the more common complications are phlebitis, extravasation of IV fluids, bruising, and hematoma formation [33]. Thrombophlebitis occurs in up to 15 percent of those with peripheral venous catheters [84]. This risk can be reduced by avoiding lower extremity IV placement, minimizing catheter movement, placing the smallest suitable catheter size, and removing the catheter as soon as possible [85-87]. Catheters placed in emergency circumstances are more prone to complications. For catheters that may need to be in place for longer periods, splinting the proximate joint and thereby preventing or minimizing catheter motion may reduce the risk for thrombophlebitis [88].

Peripheral venous catheters are thought to be rare causes of blood stream infections. The risk of infection from peripheral IV catheters and the practice of using a fixed schedule (eg, three days) to replace catheters are discussed separately. (See "Central venous access: Device and site selection in adults", section on 'Factors influencing catheter selection' and "Routine care and maintenance of intravenous devices", section on 'Catheter dwell time and replacement'.)

Less commonly reported complications include septic discitis [89], venous air embolism, pneumocephalus [90], DVT [91], skin necrosis [92], bacteremia [93], compartment syndrome, nerve injury, arterial injury [94], tendon injury, and venous aneurysm formation [33,95].

SUMMARY AND RECOMMENDATIONS

●Peripheral versus central venous access – Peripheral catheters are preferred when intravenous (IV) access is required for shorter periods, when direct access to the central circulation is unnecessary, and when smaller-gauge catheters suffice. Central venous catheters are preferred in patients receiving sclerosing medications that can damage peripheral veins. However, in patients with septic shock, vasopressors should be started via peripheral access rather than waiting for central venous access to be obtained. (See 'Indications for peripheral versus central venous access' above.)

●Anticipating difficult IV access – Factors associated with difficult IV access include a history of difficult IV access, a non-visible or non-palpable venous network, a history of diabetes, IV drug use, sickle cell disease, chemotherapy treatment, extremes of age, and underweight or obese body habitus, as well as others. The adult difficult IV access (A-DIVA) score predicts failed first attempt rate (table 1). In a patient with anticipated difficult IV access, the most experienced clinician should attempt placement and utilize IV placement aids and/or ultrasound. (See 'Anticipating difficult IV access' above.)

●Analgesia – Topical and subcutaneous anesthetics reduce the pain and anxiety associated with IV catheter insertion and should be used whenever possible (picture 3). (See 'Analgesia' above.)

●Site selection – Ideally, peripheral IV catheters are placed in distal veins in the upper extremity (figure 1 and figure 2). Do not place a peripheral IV in an extremity with an arteriovenous fistula, at a site that may interfere with an anticipated procedure, or through infected tissue. A history of mastectomy or lymph node dissection is no longer considered a contraindication to tourniquet use or venipuncture in the ipsilateral arm, provided lymphedema is not present. (See 'Site selection' above.)

●Venous dilation – Methods to enhance venous dilation and successful cannulation include the following (see 'Vein dilation' above):

•Place the anticipated cannulation site below the level of the heart

•Apply a thin rubber tourniquet 5 to 10 cm proximal to the anticipated venipuncture site

•Lightly tap or gently stroke the vein along its length in a proximal to distal direction

•Have the patient alternately clench and relax their fist

•Elevate the skin temperature by applying a warm compress

●Insertion technique – The steps of the landmark percutaneous technique are in the following pictures (picture 4 and picture 5 and picture 6). If correctly placed, fluids should infuse easily without pain or swelling at the catheter site, and the catheter can be secured (picture 7 and picture 8). (See 'Landmark percutaneous technique' above and 'Securing the catheter' above.)

●Ultrasound-guided venous access – In a patient with anticipated difficult IV access (table 1) or after two failed attempts at the landmark technique, we recommend using point-of-care real-time ultrasound guidance for peripheral IV catheter placement (Grade 1B). The equipment (eg, ultrasound machine, longer catheters) must be available, the operator should have proficiency in real-time ultrasound guidance, and the patient's clinical status has to allow for the attempt. (See 'Role of ultrasound guidance' above.)

●Complications – Common complications include phlebitis, extravasation of IV fluids or medications, bruising, and hematoma formation. Localized pain, redness, or swelling or impaired infusate flow suggests a complication. (See 'Monitoring' above and 'Complications' above.)

If extravasation of a vasopressor occurs, the catheter should be aspirated while it is removed and phentolamine injected subcutaneously around the extravasation area. (See 'Indications for peripheral versus central venous access' above.)