Intra-arterial catheters: An evidence-based review of device design, function and application

Abstract

The intra-arterial catheter is a fundamental tool in contemporary critical care medicine. Intra-arterial catheters are widely used for a range of diagnostic and therapeutic purposes, and catheter insertion is an important clinical skill for clinicians managing critically unwell patients. The concepts and practical implications of catheter design on procedural technique and outcomes are frequently overlooked. This narrative review describes the clinical application of arterial catheters, the evidence supporting their use, and the rationale for key device characteristics.

Key Words: Arterial line; Intensive care; Invasive monitoring; Arterial blood gas

Core Tip: Given the variety of available catheter products, operator expertise, patient circumstances and healthcare settings, there is insufficient evidence to identify the best devices and catheterization techniques. Intra-arterial catheter insertion and utilization practices must be individualized.

INTRODUCTION

The intra-arterial catheter is a valuable tool for directing the management of critically ill patients. Intra-arterial catheters are utilized for approximately 40% of patients admitted to intensive care units (ICUs) in Europe and the United States[1-3], including many cases where they are placed in the emergency department or operating room prior to ICU arrival[3]. Intra-arterial catheters were developed more than 50 years ago to enable continuous invasive hemodynamic monitoring and reliable access to arterial circulation, thereby facilitating precise, responsive manipulation of the cardiovascular and cardiopulmonary systems in patients with tenuous hemodynamic states. Insertion of an intra-arterial catheter typically involves percutaneous access of an appropriately selected artery. Inserting a catheter transducer system directly into the arterial lumen provides more accurate blood pressure measurements than noninvasive methods in unstable patients and makes it easier for healthcare providers and more comfortable for patients when frequent arterial blood sampling is required[4,5].

Although intra-arterial catheter placement is an important and relatively straightforward skill that requires minimal equipment, complications and technical failures are common. Patient-level evidence to guide the use of intra-arterial catheters is limited. Ideal catheter properties include biocompatibility and hemocompatibility, resilience to kinking or collapsing, resistance to degradation, softness, and a comfortably small caliber. A greater appreciation by clinicians of theoretic design principles may refine practice and improve outcomes. This narrative review explores the process of intra-arterial catheter insertion, the impact of device structure, and external factors that influence outcomes. This article is intended for physicians who may be tasked with utilizing an intra-arterial catheter or treating critically ill patients.

Intra-arterial catheters are also known as arterial or intra-arterial lines and are hereafter referred to as arterial lines. This article implies radial arterial catheterization unless otherwise stated, although content is generally applicable to most insertion sites, and specifically relates to adult patients rather than pediatric. The terms ‘catheter’ and ‘cannula’ are used interchangeably. Some related issues are not discussed in this review, such as resuscitation goals, troubleshooting, and waveform interpretation.

A structured search of the PubMed database was performed from inception to June 2025 using a range of pertinent search terms and combinations, such as “arterial catheter” and “design”. Results were screened for relevance. A broad selection of articles was obtained, including clinical trials and commentaries. Additional papers were retrieved by manually searching reference lists. Articles were allowed in any language. Results of the literature search were synthesized to generate this narrative review, prioritizing publications with higher levels of evidence.

DEVICE DESIGN AND FUNCTION

Device category

Three device categories are commonly used for arterial line insertion, each involving a specific procedural technique. These include the catheter-over-needle technique, integral-wire modified-Seldinger technique, and classic Seldinger technique (Figure 1). A standard peripheral intravenous cannula (e.g., BD Insyte, Becton Dickinson, UT, United States) represents the archetypal catheter-over-needle system in which a pliable sheath is advanced directly over an inner metallic needle after vessel puncture. The integral-wire modified-Seldinger method utilizes a coaxial assembly incorporating a guidewire within a needle and cannula (e.g., Arrow QuickFlash, Arrow International, PA, United States), whereby the integrated guidewire is advanced through the needle after arterial puncture to facilitate subsequent advancement of the outer sheath. The classic Seldinger technique involves a separate access needle, wire, and catheter (e.g., Leadercath, Vygon, France) that are placed sequentially into the target vessel.

Figure 1 Typical examples of products commonly used for radial arterial line insertion. A: Catheter-over-needle (20G BD Insyte); B: Modified-Seldinger (20G Arrow QuickFlash); C: Seldinger (20G Vygon Leadercath) method.

There is limited evidence to support the superiority of one insertion method over another. In observational studies of radial arterial line insertions, Seldinger-based techniques employing a guidewire were associated with fewer puncture attempts and shorter procedure times than a catheter-over-needle technique[6]. In a South African randomized controlled trial (RCT) of 195 arterial line insertions in the ICU, the failure rates of the catheter-over-needle, integral-wire modified-Seldinger and Seldinger methods were 24%, 17% and 7%, respectively (P ≤ 0.02)[7]. In smaller prospective trials of patients undergoing elective surgery and anesthesia, there were no differences in overall catheterization success between an integral-wire modified-Seldinger method and a catheter-over-needle method[8-10].

Published comparisons are confounded by inconsistent clinician experience, patient populations, and frequency of ultrasound guidance. Outcomes may depend on operator expertise, and anecdotally, the catheter-over-needle method can be deployed just as effectively by experienced providers, particularly anesthetists, among whom this technique appears to be more common[11]. Providers in the South African RCT were relatively inexperienced registrars. Areas of difficulty for novice clinicians may be overcome with experience. The Seldinger technique may be preferred by many clinicians because arterial puncture is readily identified, whereas the feedback of continued pulsatile arterial flow is less pronounced with a modified-Seldinger or catheter-over-needle method. More precise needle tip positioning may be necessary with the catheter-over-needle method. The most frequent reason for unsuccessful catheter-over-needle insertion is difficulty in advancing the plastic cannula despite perceived arterial puncture.

Most commonly marketed products are available in a range of hub shapes and profiles. Hubs can vary in height and length, as well as in the presence or absence of wings and ports. There are no robust data for the effect of hub design. When performing arterial line insertion with the catheter-over-needle approach, open cannula systems may be preferred over closed systems because the safeguard mechanisms in closed systems reduce versatility and may reduce the likelihood of successful cannulation[12].

The intended catheterization site influences device suitability. Most arterial line insertion studies concern the radial artery but also likely apply to other peripheral sites. Arterial line placement in the large central femoral artery is almost always performed with the classic Seldinger technique. This perhaps reflects tradition and the fact that catheter-over-needle or modified-Seldinger systems of a suitable length for femoral access become unwieldy to handle.

Catheter length and diameter

Transducer signal quality and the accuracy of blood pressure readings are theoretically influenced by catheter length and cross-sectional area. In laboratory conditions, the resistance produced by a longer narrower catheter causes lower resonant frequency response and more signal damping with distortion of the arterial waveform compared to a shorter wider catheter. Catheter radius appears to be a stronger determinant of flow than length. However, observations from preclinical studies do not always translate into real-world practice. In human studies of standard arterial line products between 20G and 24G diameters, there was no significant difference in blood pressure measurements or waveforms[13,14].

The potential advantages of using a larger catheter gauge must be weighed against the increased risk of intravascular thrombosis. As catheter diameter increases relative to the vessel wall diameter, there is progressive obstruction to surrounding blood flow and a proportionate rise in thrombosis incidence. In an RCT of 30 patients in Turkey, those assigned to radial catheterization with a 22G or 20G cannula prior to general anesthesia had arterial occlusion rates of 6% and 26%, respectively (P = 0.02)[14]. Similarly, in an RCT of 108 patients comparing 20G and 18G radial arterial lines, the rates of occlusion were 8% and 34%, respectively (P ≤ 0.05). These findings are consistent with several non-randomized studies[15,16]. Some experts recommend a catheter-vessel ratio less than 45%[17,18]. A 20G catheter, the most common radial arterial line size for adults, has an outer diameter of approximately 1.1 mm (Table 1), while the average diameter of the radial artery at the wrist in adults is approximately 2.5 mm, giving an approximate ratio of 44%. Owing to the spacious diameter of the femoral artery, the rate of thrombotic complications is significantly lower for femoral arterial lines than for radial and other peripheral lines[19] (Table 1).

Table 1 Approximate dimensions for needles, wires and cannulae utilized in arterial catheterization; note that minor variability exists between manufacturers, products, and measurement systems.

Needle or catheter gauge	Needle or catheter outer diameter (mm)	Matching guidewire thickness (inches)	Gravity flow rate (mL/minute)
22G	0.7-0.9	0.014	35
21G	0.8-0.9	0.018	60
20G	0.9-1.1	0.025	65
18G	1.2-1.3	0.035	100

Other disadvantages of a larger arterial line include increased procedural difficulty and hematoma formation. In the Turkish RCT, the 20G cannula group required twice as many puncture attempts (median of 1 vs 2 punctures, P = 0.02) and sustained more hematomas (33% vs 7%, P = 0.02) than the 22G group[14]. Further comparative trial data on bleeding risks are limited. Modern needles and catheters are manufactured with the thinnest possible walls to maximize their internal diameter while minimizing external diameter and maintaining integrity. Wall thickness differs by less than ~0.2 mm among currently available arterial line products.

An arterial line should be long enough to ensure adequate purchase within the target vessel. In prospective studies of peripheral intravenous cannulation in the emergency department, the incidence of dysfunction or dislodgement was significantly lower when at least 2.5 cm of cannula length was positioned within the vessel[20,21]. With average depths from the skin to the radial and femoral arteries in adults of approximately 0.3 cm and 1.7 cm, respectively, standard arterial line kits generally provide sufficient length and stability. Peripheral vascular catheters are manufactured in lengths typically ranging from 30 mm to 50 mm, with the specific dimensions determined somewhat arbitrarily by manufacturing practices and findings from experimental studies.

The optimal length of an arterial line remains uncertain, aside from ensuring that an adequate segment is positioned within the vessel lumen. In vivo, catheter length shows little association with thrombotic complications. Although it is common practice to use longer lines (e.g., Leadercath, Vygon, France) when extended use is anticipated, such as in the ICU, and shorter lines (e.g. BD Insyte, Becton Dickinson, UT, United States) when only brief use is expected, such as preoperatively for elective general anesthesia, this approach has not been formally evaluated.

Parameters of standard arterial line products that stocked in the author’s local hospitals are outlined in Table 2.

Table 2 Characteristics of common commercially available arterial line products; these examples represent classic dimensions but many size combinations are available.

Product	Pink BD Insyte	Blue BD Insyte	Vygon Leadercath	Arrow Quickflash	Arrow Integrated	Arrow Seldinger	BD Floswitch
Assembly style	CN	CN	S	IW	IW	S	CN
Intended insertion site	Radial	Radial	Radial	Radial	Radial	Femoral	Radial
Catheter material	Polyurethane	Polyurethane	Polyethylene	Polyurethane	Polyurethane	Polyurethane	Polyurethane
Catheter gauge	20G	22G	20G	20G	20G	18G	20G
Catheter length (cm)	3	2.5	8	3.8	4.5	16	4.5
Introducer needle gauge	21G	23G	20G	21G	22G	18G	21G
Introducer needle length (cm)			3.8			7
Guidewire material			Stainless steel	Stainless steel	Stainless steel	Stainless steel
Guidewire gauge (inches)			0.021	0.018	0.018	0.025

CN: Catheter-over-needle; S: Seldinger; IW: Integral-wire modified Seldinger.

Catheter material

Contemporary vascular catheters are typically made with thermosensitive polyurethane. Alternative materials include polyethylene and polytetrafluoroethylene (PTFE). Thermosensitive plastic is considered advantageous because it remains relatively stiff at room temperature, facilitating percutaneous insertion, while softening within body tissues to reduce the risk of endothelial injury. Because of its favorable properties, polyurethane has gradually become the predominant material for vascular catheters. Polyethylene and PTFE are stiffer polymers than polyurethane. In observational and preclinical studies, polyurethane peripheral catheters have consistently outperformed PTFE catheters in terms of phlebitis rates, dwell time, ease of percutaneous advancement, and clinician-reported satisfaction[7,22-30]. Comparative studies of PTFE vs polyethylene-like catheters[31,32] and polyethylene vs polyurethane catheters[33-37] reported conflicting results. Silicone is a soft material infrequently used for arterial lines. Silicone catheters have demonstrated poorer patency rates in observational studies, consistent with studies in animal models in which silicone’s porosity promoted intraluminal thrombosis and its flexibility allowed luminal collapse under negative suction during blood aspiration[38]. Currently, evidence is insufficient to support the routine use of catheters embedded with antimicrobial or antithrombotic surface coatings.

Entry needles

Percutaneous vessel access requires a rigid, sharp entry needle, either housed within a cannula, as in catheter-over-needle systems, or be used separately to introduce an access wire, as in Seldinger-based systems. Needles are typically manufactured in stainless steel because of favorable biomedical qualities in vitro and cost-effectiveness. There is no evidence specifically favoring one type of access needle; rather, selection is guided by more practical factors such as the desired indwelling cannula gauge, access wire gauge, and operator preference. Finer needles theoretically reduce bleeding complications whereas needles with a larger bore allow clearer recognition of arterial puncture. There are very slight variations in needle bevel geometry among commercially available products, with theoretical advantages to different degrees of sharpness and shape, but their impact in practice is likely negligible[25,39,40]. Dexterity and control may be enhanced by choosing the shortest needle that is sufficient to cannulate the artery.

Arterial line insertion is frequently performed under ultrasound guidance. Practitioners should be aware that the needle in a catheter-over-needle device is less echogenic than a bare metal needle because of blurring by the outer plastic sheath.

Guidewires

Seldinger-based radial arterial line kits contain straight-tipped guidewires. Straight-tipped wires pass more freely through small target vessels than J-tipped wires[41,42]. Femoral arterial line placement is usually performed over a J-tipped guidewire. J-wires are theoretically atraumatic to intravascular endothelium and easily navigate through the femoral artery’s large diameter[43,44]. The arc of a J-tip may also prevent misdirection into small femoral arterial tributaries.

Guidewire tips are usually soft and floppy relative to their firmer shaft. The metallic spring wires contained in commercial arterial line kits are constructed from stainless steel or nitinol. Steel provides more stiffness whereas nitinol is more pliant and less prone to kinking. Steel and nitinol are hydrophobic and comfortable to handle. A wide variety of guidewires are available, supported by extensive ex vivo experience but limited by a paucity of comparative clinical trials. Therefore, the wire products deployed in practice are typically dependent on operator preferences and judgment. The selected wire and introducer needle must have concordant diameters.

Summary

The approach to arterial line insertion relies on physician discretion. Decisions must be nuanced and individualized because there is insufficient evidence to uniformly recommend a superior arterial line device or insertion method. It is reasonable to conclude that there are no major differences between a catheter-over-needle and a Seldinger-based technique, although Seldinger techniques may be more successful for inexperienced operators. In general, the physical and chemical properties of standard commercially available products are sufficiently similar that brand and style selection is determined primarily by physician preference and experience.

DEVICE APPLICATION AND EXTERNAL FACTORS

Indications for use

Standard indications for arterial line placement include the need for continuous hemodynamic monitoring, repeated arterial blood gas measurements or regular phlebotomy in a critically ill patient, and situations where non-invasive recordings would be considered unreliable. However, definitive data that directly substantiate these indications and the use of arterial lines more broadly are somewhat limited.

The utility of arterial lines is inferred indirectly from evidence that superior blood pressure control improves outcomes across numerous conditions, as well as from their perceived value in facilitating close monitoring of patients receiving vasoactive medications. The presence of arterial lines has been associated with improved blood pressure stability in a range of acute indications[45-49], and invasive monitoring is associated with reduced mortality in septic patients in the ICU[50]. Arterial line placement is recommended for individuals with shock requiring vasopressors[51-53] and should also be considered as a management aid in individuals with blood pressure lability.

The need for hemodynamic monitoring is broadly interpreted and on a case-by-case basis. For example, appropriate indications could include intra-operative use during cardiac surgery, treatment of heart failure with non-invasive ventilation or acute respiratory distress syndrome with mechanical ventilation, and observation following subarachnoid hemorrhage. The subset of patients with such indications who warrant arterial line placement is poorly defined. There is also no consensus on when non-invasive readings would be considered unreliable; however, common scenarios may include obesity or tachyarrhythmias. The threshold frequency of blood draws at which an indwelling catheter becomes preferable to repeated needle sticks for blood gas analysis is unknown; however, many clinicians recommend catheter insertion when arterial sample is anticipated at least once daily.

Contraindications

Contraindications to arterial line placement may be considered relative or absolute, depending on the urgency of monitoring and the availability of alternative insertion sites. Arterial line insertion should be avoided at sites with local infection, anatomical abnormalities, proximal traumatic injuries, severe Raynaud’s syndrome or peripheral vascular disease. Sites with vulnerable circulation should be avoided if feasible, such as the brachial artery. The role of the Allen’s test before radial catheterization is controversial. Other contraindications include coagulopathy, thrombocytopenia, or an environment in which resources are inadequate to properly monitor the patient.

Insertion technique and best practices

The steps of arterial line insertion are described elsewhere[54,55] and will not be covered in detail in this article. However, we explore several technical points because of their particular educational value in improving procedural success. A working knowledge of the basic components and skills of arterial line insertion is assumed.

Site selection: The radial artery is the most frequent site for arterial line insertion. In a large Australian ICU dataset, radial and femoral arterial lines accounted for 83% and 8% of arterial lines, respectively[56]. In an American anesthesia database, more than 90% of arterial lines for intraoperative indications were radial[57]. Less common sites include the brachial, dorsalis pedis and axillary arteries. Radial arterial lines are associated with reduced infective and bleeding complications, are comfortable for patients, and are relatively easy to place. Femoral arterial lines are less likely to dislodge or thrombose, more accurately measure central arterial pressure, and are also relatively straightforward to place. The right radial artery is used more frequently than the left, as accessing the right side of the patient is reportedly more ergonomic for right-handed proceduralists[6,56]. Although comfort presumably optimizes success, the effect of laterality on outcomes has not been examined. For radial arterial line insertion, the distal quarter of the forearm at least 4 cm from the wrist joint was associated with improved procedural success vs distal or proximal locations along the radial artery in small RCTs when ultrasound guidance was used[58,59], whereas a lower site within 4 cm of the wrist was superior in observational studies when placing catheters blindly[60-62].

Patient positioning: Moderate wrist dorsiflexion raises the radial artery closer to the skin and increases vessel diameter. Prospective trial evidence indicates that dorsiflexion to approximately 45 degrees improves insertion success compared with both greater and lesser degrees of dorsiflexion[63,64]. The optimal method for maintaining wrist positioning has not been formally studied. In common practice, the hand is supinated and immobilized by placing a towel or board beneath the wrist and gently securing the hand and thumb with tape to prevent movement. Experts advocate advancing the needle at an angle of 15-45 degrees. The optimal operator position and the most effective technique for gripping the needle and cannula during placement remain uncertain.

Ultrasound guidance: Ultrasound is increasingly utilized for arterial line insertion and many guidelines now state that ultrasound guidance should be considered. Regarding radial arterial line placement, meta-analyses of RCTs demonstrated higher first-pass success rates with ultrasound guidance compared to blind percutaneous insertion with palpation[65,66]. For example, in an RCT of 40 patients undergoing general anesthesia in Denmark, there was a first-pass success rate of 95% in the ultrasound-guided group vs 58% in the palpation-guided group (P ≤ 0.01)[66]. RCT findings on procedure times and overall success rates across all attempts have been contradictory[65,66]. Ultrasound may be less beneficial for physicians with greater experience[67]. A short-axis view is generally regarded as simpler than a long-axis view[68]. A small RCT in ICU patients showed superior outcomes with ultrasound guidance during femoral arterial line insertion[69], although results from RCTs evaluating blind percutaneous vs ultrasound-guided femoral puncture in interventional cardiology settings were mixed[70-72]. Ultrasound is likely to be particularly helpful in subjects where pulse palpation is difficult, such as those with hypotension, obesity, or peripheral edema.

Local anesthesia: Local anesthesia should be administered prior to the procedure unless the patient is deeply sedated. There is strong evidence that local anesthesia reduces pain during arterial puncture[73-75]. Whether local anesthetic instillation affects cannulation success is unclear; however, a survey of junior doctors in Britain found that most did not perceive the use of local anesthesia as making the procedure more difficult[73].

Sterility and antibiotic prophylaxis: A sterile technique including skin antisepsis, drapes and sterile gloves is recommended by guidelines for radial arterial line placement, founded on very limited evidence[76,77]. A large RCT of arterial line insertion with a sterile vs an aseptic non-touch technique showed no differences in the incidence of infective complications[78]. Observational studies found that infection rates were higher amongst arterial lines inserted in the emergency department or operating room than in the ICU, which may be due to time constraints and more frequent use of aseptic non-touch technique in these environments as opposed to sterile technique. A sterile gown is not required for radial arterial line insertion due to a paucity of corroborating evidence.

Routine intravenous peri-procedural antibiotic prophylaxis is not recommended by guidelines. This advice is based on the findings of randomized trials of central venous catheters[76,79,80]. The incidence of catheter-associated infection appears similar for arterial lines and central venous catheters[81,82].

Catheter cares: Some of the key nursing and maintenance practices that affect arterial line outcomes are summarized in Table 3[76,83-90].

Table 3 Important aspects in the daily care of arterial lines.

Daily care	Explanation
Dressings	The optimal dressing products, frequency of dressing changes and frequency of site inspections are uncertain. A common practice is to replace dressings weekly or sooner if they become loose or unclean. Local institutional policies should be followed. A topical cleansing agent should be applied to the catheter site during a dressing change to prevent infection[76,83]
Antibiotic prophylaxis	Daily antimicrobial prophylaxis to prevent infection while the arterial line is in situ is not advised, as evidence is insufficient
Securement	Both sutures and adhesive dressings are suitable methods for catheter securement. No consistent differences in adverse events have been demonstrated[84]. Sutures were associated with fewer arterial line displacements in retrospective studies compared with sutureless fixation dressings but may predispose to infection
Flushing	A continuous slow infusion of normal saline is delivered through the arterial line to maintain patency. A pressure bag attached to the transducer system is commonly inflated to 300 mmHg to deliver fluid at a rate of ~3 mL/hour. This configuration reduced adverse events compared with intermittent flushes or infusion rates[85,86]. Heparin does not improve patency over normal saline[87]
Routine catheter changes	Routine arterial line changes are not recommended. Regular arterial line replacement does not reduce the risk of catheter-related sepsis as opposed to a process of replacement only when clinically indicated[88-90]. The relationship between catheter dwell time and the incidence of infection is unclear

Complications

The main mechanical complications of arterial line placement include thrombosis and embolism, vessel injury, ischemia, and bleeding. Infective complications may be local or systemic. As mentioned in preceding sections, the frequency and severity of complications vary with patient circumstances, insertion sites, duration of use, procedural technique and, to a much lesser extent, device characteristics.

One of the strongest predictors of procedure-related complications may be operator experience. There is ample literature describing a clear association between inexperience and worse procedural outcomes across a range of critical care procedures[91,92]. Nonetheless, the effect of operator experience specifically for arterial line placement is poorly studied. Other notable risk factors for arterial line complications at any site include hypotension, peripheral vascular disease, catheterization under emergent conditions, and illness severity[56].

Special patient circumstances

An individualized approach to arterial line placement is needed in many circumstances without directly relevant studies. For example, obesity may reduce the reliability of pulse palpation and may increase the complications of femoral arterial line placement. In individuals with severe atherosclerosis, who are at greater risk of mechanical complications, the femoral artery may be a more appropriate insertion site than smaller arteries. Alternatively, during radial cannulation, a more cephalad site along the radial artery may be considered. In patients with an existing arteriovenous fistula for hemodialysis, or in those anticipated to require one in the future, radial cannulation may compromise long-term patency and is therefore discouraged. Finally, in operative settings, anesthetists must anticipate surgical steps to ensure uninterrupted monitoring and that the catheter is reachable throughout surgery. For example, a radial arterial line is typically avoided in cardiac surgery when unilateral radial artery harvest is planned, whereas bilateral lines may be required during aortic surgery.

Guideline recommendations

There are no published guidelines specifically dedicated to the insertion and maintenance of arterial lines. However, continuous hemodynamic monitoring is often recommended as a management component, such as in guidelines for sepsis[89], neurosurgery[93], and cardiac anesthesia[94].

FUTURE DEVELOPMENTS

Trends in arterial line use

Arterial lines are prevalent in contemporary practice, although their utilization is declining[95,96]. For example, Medicare data from Australia demonstrate that the per capita frequency of arterial line placement roughly halved between 1994 and 2024[95]. Possible explanations include improvements in non-invasive monitoring technologies, reduced morbidity with the uptake of minimally invasive surgery over traditional open or radical approaches, and a lack of evidence justifying the role of invasive hemodynamic monitoring in most situations[91].

Despite decades of experience, the implementation of arterial lines continues to be subject to considerable regional heterogeneity and diverse physician and center practices[3,57,97-99]. The use of arterial lines has increased over time in emergency departments and among patients with sepsis but appears to have declined in intraoperative settings and in patients with diagnoses other than sepsis. In emergency departments in the United States, arterial lines are more likely to be placed by physicians in academic centers than in rural settings[99]. Studies from Australia and the United States report that about two-thirds of arterial lines are placed in ICUs, while about one-third are placed in other areas[57].

Invasive monitoring may be underutilized in some situations that are traditionally managed without the placement of an arterial line. Arterial lines are seldom used in coronary care units or respiratory high-dependency bays, despite the frequent need in these settings for advanced therapies such as non-invasive ventilation or inotropic support. Many patients admitted to these units could benefit from continuous monitoring; however, few such studies have been performed, and further research to identify unrecognized indications for arterial line placement is warranted. Because the use of arterial lines is essentially confined to ICUs in most hospitals, extension into other settings must be accompanied by proof of improved patient outcomes and cost-effectiveness, as well as provision of adequate healthcare resources and training.

Considering the prevalence of arterial line use in contemporary practice, the overall body of relevant literature is lacking and few recent scientific advancements have been made. The results of a small number of relevant prospective clinical trials that are currently underway will be helpful: Two upcoming RCTs are evaluating arterial line insertion sites, and one is evaluating the utility of invasive monitoring in arthroscopic shoulder surgery.

Non-invasive alternatives

A host of non-invasive alternatives to arterial lines for continuous monitoring are being investigated in preclinical and clinical studies. Proposed options include wearable sensor technologies based on bioimpedance, photoplethysmography, electrocardiography, tonometry, or ultrasound. The technology appears promising but is yet to enter mainstream practice. In the future, non-invasive devices may permit closer monitoring for patients in lower-acuity or remote environments like general medical wards or the community. Additional research is necessary before non-invasive modalities can acceptably replace the present clinical approach to hemodynamic monitoring and treatment.

CONCLUSION

Arterial line insertion is a crucial skill that enables physicians to provide responsive, exact care of critically ill patients. There is a wide variety of available arterial line products in current practice, without convincing evidence of superiority for one over another. The choice of device and insertion technique must be decided through a combination of theoretical concepts, patient circumstances, imperfect evidence, and physician judgment. The value of arterial lines is potentially unrealized in many conditions, and further evaluation of appropriate indications and practical application is needed.