Abstract
Background:
Peripheral intravenous access is no longer limited to the standard intravenous catheter (cannula). Devices varying in length, material and insertion technique, are increasingly accessible. There is substantial variability surrounding the nomenclature and use of these devices in the literature. We wished to understand the attitude of vascular access specialists towards the nomenclature and use of peripheral intravenous catheters (PIVCs), long peripheral catheters (LPCs) and midline catheters (MCs).
Methods:
A 15-question electronic survey was sent to members of the Association of Vascular Access (AVA) regarding the nomenclature and use of PIVCs, LPCs and MCs.
Results:
A total of 228 participants completed the survey. Approximately two-thirds of respondents use LPCs (65.8%) and MCs (71.9%) in their clinical practice. The most common indication for LPCs was difficult venous access (56.5%), while the most common indication for MCs was medium-term (1–4 weeks) intravenous therapy (62.7%). The majority of participants (57.9%) agreed with the following classification of peripheral intravenous devices: PIVCs: 2 to 6 cm in length, terminating distal to the axilla; LPCs: 6 to 15 cm in length, terminating distal to the axilla; MCs: 15–25 cm in length, terminating in the axilla.
Participants suggested that the length of the catheter should be considered a general recommendation, as LPCs and MCs should be primarily differentiated by tip location.
Conclusions:
The majority of vascular access specialists from AVA have incorporated LPCs and MCs into their repertoire of peripheral venous access tools. We envisage that their use will increase as the clinical community becomes more familiar with these devices.
Introduction
In recent years, there has been a rapid growth in the variety of peripheral intravenous (IV) devices available on the market. Catheters, varying in length, material and insertion technique, are increasingly common as manufacturers seek to address healthcare demand for versatile peripheral access. Therefore, peripheral IV access is no longer restricted to the ‘standard’ peripheral intravenous catheters (PIVCs) or ‘cannulae’. Patients requiring medium-term IV therapy (1–4 weeks), or with difficult venous access, can now receive treatment via long peripheral devices such as long peripheral catheters (LPCs) and midline catheters (MCs).1–3
PIVCs are the most common devices for peripheral IV access; they are 2 to 6 cm in length and terminate in the extremities. LPCs are 6 to 15 cm in length and are typically placed in the forearm or upper arm. They terminate before the axilla and, hence, should not extend beyond the mid-basilic, -brachial or -cephalic vein. MCs are the longest peripheral device, between 15 and 25 cm in length. MCs extend as far as the axillary vein but do not enter the subclavian vein.2–4
All three are peripheral devices and therefore, they only allow for the safe administration of peripherally-compatible infusates. 5 However, there is substantial variability in the nomenclature of these devices in the literature; this might be due to the considerable range of devices commercially available in different countries but also to the utilisation of diverse brand names by various manufacturers (e.g. PowerwandTM Midline Catheter, Leaderflex® catheter, Smartmidline®, etc.). Furthermore, significant variability is also present regarding the use and indications (e.g. hospital versus home therapy; patients with difficult venous access (DIVA), etc.), technique of insertion (e.g. conventional palpation technique versus ultrasound guidance; catheter over needle versus direct Seldinger technique) and post-insertion care (e.g. securement; need for heparinised lock, etc.). 3 Regarding the use of ultrasound, although LPCs and MCs can be safely placed without ultrasound, the use of ultrasound-guidance is generally recommend as these longer devices have proved particularly useful for accessing deep veins in patients with DIVA. 3
In addition, while PIVCs often require replacement after a few days, LPCs and MCs can remain in situ for multiple days or weeks; however, this is not only depending on the clinical scenario but also on institutional protocols and manufacturer’s recommendations.
Despite the challenges highlighted above, current evidence suggests that LPCs and MCs are safe and reliable in both adults and children, providing improved quality of care over PIVCs for multi-day intravenous therapy.3,6
We have previously highlighted the aspects surrounding the nomenclature and use of long peripheral devices in our editorial and systematic review published in The Journal of Vascular Access.2,3 Moreover, we presented and discussed these findings at the 2019 Association of Vascular Access (AVA) Annual Scientific Meeting.
As a follow-up, we surveyed vascular access specialists from AVA to understand their attitude towards the nomenclature and use of both LPCs and MCs. The results of this survey are summarised in this article.
Methods
A 15-question survey was developed and distributed via the web-based platform Qualtrics Customer Survey Software (Qualtrics®, USA). The survey was approved by the Monash Health Human Research Ethics Committee (Reference Number: HREC/17/MonH/534), the AVA Chief Operations Officer and the AVA Director of Clinical Education.
In December 2019, the survey was emailed to all AVA members, an American-based organisation with over 2600 members across the world. Table 1 displays the questions administered in the survey. For some questions, participants could pick only one answer, while for others, participants could pick multiple answers (this was clearly labelled with each question). There were also optional text-based questions where participants could answer freely. A brief introductory sentence on the welcome page explained the rational for the survey; ‘There is a clear lack of consensus surrounding the nomenclature and use of longer-length peripheral IV devices (e.g. long peripheral catheters, midline catheters) in the literature. We wish to seek the opinion of vascular access experts from AVA to establish a consensus name and definition for these devices. Furthermore, we wish to evaluate the use of peripheral IV devices across different institutions around the world’.
List of survey questions.
The survey was active for 1 month and was closed in January 2020. After closure, results were collated and analysed. Data are presented as number of selections and proportion.
Results
A total of 228 vascular access specialists from eight countries, including the United States (n = 208), Australia (n = 8), Canada (n = 5), Brazil (n = 2), Italy (n = 2), China (n = 1), Germany (n = 1) and Mexico (n = 1), completed the survey. Most clinicians identified their primary profession as either vascular access specialist (52.6%) or nurse (39.9%) with three-quarters (75%) working as part of a dedicated vascular access team. Over two-thirds (68.8%) of clinicians primarily worked with adult patients while the remainder worked with children (6.6%) or a mixed cohort (24.6%).
Participants were most familiar with the term ‘midline catheter’ (93.4%), followed by ‘peripheral intravenous catheter’ (91.7%) and ‘long peripheral catheter’ (82.0%). All but one (99.6%) participant agreed that PIVCs, LPCs and MCs were peripheral IV devices. The majority of participants differentiated LPCs and MCs by their length (76.3%), catheter tip location (68.4%), insertion technique (63.5%), insertion location (60.1%) and cost (54.8%). Material (36.8%) and gauge (21.5%) were deemed less important in differentiating the two devices. Six (2.6%) participants considered LPCs and MCs to be the same device.
To describe a 6–15 cm peripheral intravenous device, participants were most familiar with ‘midline catheter’ (93.4%), ‘extended dwell catheter’ (87.2%) and ‘long peripheral catheter’ (66.7%). Clinicians’ most preferred names were ‘midline catheter’ (33.8%), ‘long peripheral catheter’ (30.3%) and ‘extended dwell catheter’ (21.5%). ‘Midline catheter’ was the most familiar and preferred term amongst responders. Full results are presented in Table 2.
Nomenclature of 6–15 cm peripheral intravenous devices.
(Left) Participants could select multiple answers for this question. (Right) Participants could only select a single answer for this question.
The majority of participants (57.9%) agreed with the following classification of peripheral IV devices:
PIVCs: 2 to 6 cm in length, terminating distal to the axilla;
LPCs: 6–15 cm in length, terminating distal to the axilla;
MCs: 15–25 cm in length, terminating in the axilla.
Participants who disagreed with this classification primarily cited concerns regarding catheter length. Forty (17.5%) participants agreed with the above classification but did not agree with the range of lengths used in the definition. Another 36 (15.8%) did not believe that LPCs and MCs should be differentiated by catheter length, but rather, by tip position alone; i.e. LPCs terminate before the axilla and MCs terminate in the axilla. The remainder considered all peripheral devices from 6 to 25 cm to be ‘midline catheters’ (8.7%).
A total of 150 (65.8%) and 164 (71.9%) of participants, respectively, used LPCs and MCs at their institutions. The most common indication for LPCs was difficult venous access (56.5%), followed by deep vein access (39.1%) and medium-term IV therapy (23.9%). MCs were most often indicated for medium-term IV therapy (62.7%) and difficult venous access (33.7%). Common indications are displayed in Table 3.
Indications for 6–15 cm and 15–25 cm peripheral intravenous devices.
Participants responded in free-form text. Participants could list multiple indications. Answers were collated and summarised in this table.
The most widely available LPCs were 6 cm (62.3%), 8 cm (42.0%) and 10 cm (40.0%) in length. Less than 10% of participants had access to other lengths. LPCs were primarily inserted into the upper limb, including the forearm (84.7%) and upper arm (99.3%). The hand (1.3%) and antecubital fossa (8.7%) were generally avoided due to their proximity to points of flexion. The majority (76.3%) of participants inserted LPCs with ultrasound-guidance. At most institutions, the maximal duration for a single LPC was 4 weeks (34.7%), followed by 2 weeks (30.7%), 1 week (15.9%) and 3 weeks (10.2%). Only thirteen (8.5%) responders used LPCs for more than 4 weeks.
Discussion
The initial impetus for this survey originated through our research into the topic of peripheral IV devices. We found large variance in the nomenclature and use of 6–15 cm peripheral IV devices in the medical literature. 2 , 3 Since these devices are relatively novel, there are no official guidelines to standardise their terminology and use. Therefore, we suggested the classification of peripheral devices in PIVCs, LPCs and MCs based on the length of the catheter and tip position. 2 Institutions, therefore, have their own policies which are likely to have determined how participants answered this survey.
As a baseline, we assessed the familiarity with the terms ‘peripheral intravenous catheter (PIVC)’, ‘long peripheral catheter (LPC)’, and ‘midline catheter (MC)’. LPC was somehow a ‘foreign’ term, as it was only recognised by two-thirds (66.7%) of participants. This was expected as LPCs are the most novel of the three devices and the most varied in terms of nomenclature. We have chosen to use this term from dozens of options in the literature as we felt it provided the most appropriate description. Many clinicians may refer to this device with a different descriptive name.
There was little debate that PIVCs, LPCs and MCs were all peripheral IV devices. Participants differentiated LPCs and MCs by length, tip location, insertion technique, insertion location and cost. Depending on the clinical setting, and product used, all the aforementioned variables can be important differences. However, regardless of the insertion technique, location, size or material, we suggest that length and tip location should be the only factors to strictly discriminate between LPCs and MCs.
We have previously highlighted the confusing nomenclature used to describe 6–15 cm peripheral IV devices in the literature. 2 ‘Extended dwell catheter’, ‘midline catheter’, ‘mini-midline’, ‘long catheter’, ‘long line’, ‘long peripheral catheter’, ‘peripheral intravenous catheter’, ‘Seldinger catheter’, ‘short long line’, ‘short midline’ and ‘ultrasound-guided peripheral intravenous catheter’ are some of the common terms. Approximately nine out of ten participants had seen the terms ‘midline catheter’ (93.4%) and ‘extended dwell catheter’ (87.2%). This finding was anticipated as several manufacturers use these terms interchangeably to market their products. ‘Long peripheral catheter’ was the third most common (63.4%).
The same three terms were also the most preferred amongst participants. ‘Midline catheter’ (33.8%) was most favoured, followed by ‘long peripheral catheter’ (30.3%) and ‘extended dwell catheter’ (21.5%), although a lack of consensus was evident as none received majority support. From our data, it appears that participants narrowly supported using the term ‘midline catheter’ to refer to a 6 to 15 cm device terminating distal to the axilla. This, however, does not aid in the differentiation of two distinct peripheral devices; one which terminates distal to the axilla and one which terminates in the axilla. Moreover, MCs have traditionally been defined by their termination in the axilla.4,5
The majority (57.9%) of participants agreed with the classification of peripheral vascular devices in PIVCs, LPCs and MCs. Amongst participants who disagreed, 40 challenged the lengths (i.e. 2–6 cm, 6–15 cm and 15–25 cm respectively) and 36 believed that tip position alone should differentiate LPCs and MCs. Although this range of lengths may seem arbitrary, they are derived from appraisal of the medical literature. 3 Devices longer than 6 cm are commonly inserted using a catheter-over-guidewire (Seldinger) technique instead of the catheter-over-needle technique used for PIVCs. Similarly, devices shorter than 15 cm often do not reach the axillary vein in the adult patient and, thus, would not qualify as MCs. Defining LPCs and MCs by tip position alone, however, is a reasonable suggestion, as some products could be used as either device. This is a sentiment that we agree with and acknowledge that the lengths suggested in our definition, should be considered a general recommendation.
The participants revealed a clear trend in the utilisation of LPCs and MCs across institutions. LPCs are mostly used in the setting of difficult venous access and deep vein access. In patients lacking visible/palpable veins, participants turned to LPCs as ‘rescue’ catheters when standard PIVCs were insufficient for ultrasound-guided access of deep veins. In contrast, participants use midlines in patients requiring reliable peripheral access for medium-term (1–4 weeks) IV therapy and, in doing so, avoiding the need for central access. Thus, clinical indication is another important distinction between LPCs and MCs. The former is most useful in achieving difficult access in the acute setting, while the latter is best for reliable multi-week access.
Limitations
Our results should be considered in the context of the following limitations. Firstly, the survey cohort was a relatively selected population of vascular access specialists, the vast majority of whom were from the United States. The results, thus, primarily represent the use of LPCs and MCs from an American perspective and are not necessarily widely generalisable. The AVA mailing-list was chosen as this survey was distributed following a presentation delivered by our research team at the 2019 AVA Annual Scientific Meeting on the controversies surrounding the nomenclature of LPCs and MCs. Secondly, the results of this survey are not intended to be used as a consensus statement on the topic; a consensus statement on this topic, produced with greater rigour, would be a useful endeavour for the wider medical community.
Conclusion
Long peripheral devices provide a useful alternative to PIVCs. The majority of vascular access clinicians surveyed have incorporated LPCs and MCs into their repertoire of venous access tools. We expect their use to increase as the broader medical community becomes more familiar with these devices.
Footnotes
Acknowledgements
The Authors would like to thank the Members of the Association for Vascular Access (AVA) for taking the time to complete this survey. We particularly thank AVA Chief Operations Officer Ms Tonya Hutchinson and AVA Director of Clinical Education Ms Judy Thompson for their input during the development of the survey and their support with its distribution to AVA members.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
