Management of difficult intravenous access: a qualitative review

Mingwei Ng, Leong Kwok Fai Mark, Lateef Fatimah

Department of Emergency Medicine, Singapore General Hospital, Singapore 169608, Singapore

KEYWORDS: Difficult intravenous access; Venepuncture; Vortex; Peripheral intravenous cannulation

INTRODUCTION

Establishing peripheral intravenous access (PIV) is one of the most ubiquitous and crucial steps in managing critically ill patients. Yet only 74% of first attempts during emergency resuscitation in adults[1]are successful and this falls to an even-more-dismal 33% in difficult intravenous access (DIVA) patients.[2]

A perennial challenge faced by clinicians, DIVA impacts patient outcomes adversely by causing downstream delays in both diagnoses (difficulty in obtaining blood specimens and administering intravenous contrast for advanced imaging) and therapy (provision of parenteral fluids, blood products or drug administration to facilitate procedures such as sedation or rapid-sequence intubation).[3]Failed cannulation attempts often cause patient and clinician alike considerable frustration and distress and may lead to complications like thrombophlebitis, infection and haematoma.[4]Moreover, time-to-cannulation averages 2.5-13.0 min for most patients but can take up to 30 min to hours in DIVA cases.[5]As DIVA patients tend to distract disproportionately more time and attention of the attending emergency physicians, this inevitably compromises the care of other patients.

Although there is no consensus or universallyaccepted definition, DIVA is commonly defined as either two or more failed attempts by an experienced operator using traditional landmark-based methods of vein visualization or palpation, or the need for rescue techniques (such as ultrasound, near-infrared visualization devices or central venous cannulation[CVC]) to establish intravenous access.[6]DIVA is most frequently encountered when veins are neither palpable nor visible,[7]such as in obese, dark-skinned or oedematous individuals. Peripheral constriction in dehydrated, hypotensive patients may also render intravenous access exceedingly difficult even for experienced operators. Other causes include limited viable venous access sites due to chemotherapy,intravenous drug abuse, vasculopathy from end-stage renal failure, or frequent repeated punctures in patients with chronic medical issues leading to “vascular exhaustion”.[6]

Risk factors for DIVA are well-recognized and predict scores like A-DIVA scale have been developed.[8]Published DIVA strategies, however, mostly involve various pointof-care ultrasound techniques, while other “tricks-of-thetrade” for managing DIVA are largely relegated to case series, letters to the editor and informal non-published material like blogposts and tweets. Given the increasing prevalence of DIVA and the relative paucity of updated review articles on this topic, this paper seeks to provide a qualitative review of available literature and consolidate pragmatic strategies for overcoming DIVA.

METHODS

We conducted a systematic search of the existing literature on PubMed using the keywords “difficult intravenous access”, “peripheral vascular access” and“peripheral venous access”. Citations of relevant review articles were also searched. Paediatric-specific articles were excluded if the proposed strategies could not be translated to adults (for instance, superior sagittal sinus cannulation for emergency infant venous access). Studies on animal models were also excluded. The search was not limited by language. Resources relating to emergency medicine and anaesthesia were also searched to elicit pearls on how others manage DIVA.

RESULTS

The database search of articles up to 31 August 2021 yielded 530 articles after duplicate removal, of which 222 were selected for full-text review after abstract review. Twenty articles were eliminated as they focused on prognostication factors, prevalence or complications relating to DIVA which were beyond the scope of this review. Relevant articles were evaluated qualitatively for DIVA strategies, which were then categorized and incorporated into a pragmatic algorithm.

Operator-related strategies

Optimization

Each failed cannulation attempt makes subsequent attempts harder as the remaining viable sites become depleted while doubt and despair creep into both operator and patient. Optimizing the conditions to maximize one’s chances of first-attempt success is therefore of utmost importance. By ensuring the surroundings are clean and well-lit,[9]preparing and laying out equipment within easy reach (including additional supplies if one misses)[10]and improving the ergonomics by positioning the patient and oneself (by kneeling, crouching or sitting) such that both are as comfortable as possible,[11]one might improve the success rate of cannulation.

Failed cannulas are usually removed immediately with the tourniquet, but this may cause profuse bleeding from the failed puncture site that restarts upon tourniquet reapplication. The “Advik technique” advises removing the needle but capping and leaving the failed cannulainsitu. The tourniquet is maintained to facilitate subsequent attempts and removed together with the failed cannulas only after successful vascular access.[12]This minimizes bleeding and saves precious time as haemostasis does not need to be secured between attempts.

While peripheral intravenous catheters (PIVCs)may sometimes be required under high-stress settings,it is to remain calm because a rushed, nervously attempt would more likely fail.[13]One ought to remember that patient anxiety can worsen vasoconstriction[14]too and should thus always seek to exude confidence and allay the patient’s fears. One can also inquire from the patient which sites have had the highest success rate previously[15]as this may offer valuable clues.

Vein identification

One should search carefully and systematically for a suitable cannulation site by applying a tourniquet early and examining the non-dominant upper limb[16]first in a distal-to-proximal manner,[17]before moving on to the dominant limb. A distal-to-proximal strategy preserves the integrity of more proximal sites after unsuccessful punctures distally and reduces the risk of extravasation or phlebitis from vesicant infusions.[18]As veins tend to be relatively fixed where they converge,[19]one should pick these convergences and puncture from sideways to minimize vein-rolling.[20]Pulling the skin taut and providing traction can help one prevent the skin from folding up and dislodging the vein when advancing the needle.[18]The ideal vein would be visible, straight and large, refill when depressed, and feel soft and “bouncy”on palpation.[21]

The small digital and carpal veins are easily overlooked and one should deliberately inspect these.Veins along the extensor surface of the posterior arm are particularly clumsy to cannulate and may have been spared by other clinicians (or self, in the case of exintravenous drug use). Although lower extremity veins are best avoided due to increased risks of phlebitis,line-related sepsis and lower extremity embolism from immobilization,[22]the saphenous veins are usually prominent and may prove useful if no other veins are suitable. One may even have to resort to unusual sites such as superficial veins of the shoulder, chest wall, thigh or even dilated subcutaneous abdominal wall collateral veins[23]in emergency.

1) External jugular venous cannulation

The external jugular vein (EJV) courses over the sternocleidomastoid and presents a useful, easily accessible site for cannulation as it is a large vein with a relatively fixed and superficial anatomy. One must recline the patient into a Trendelenburg position to distend the veins and minimize air embolism - which would unfortunately not be possible in severe dyspnoea or orthopnoea. Using the stethoscope as a tourniquet,[24]forced expiration manoeuvres[25]and occluding the EJV against the clavicle while anchoring the vein using one’s thumb and index finger[26]can further augment venous distension. In cases where the patient’s mandible is in the way (especially those with short necks or who cannot rotate their necks), one could bend the proximal-third of the angio-catheter slightly to maintain a shallow angle of approach.[27]One should then make a single, decisive puncture with a large-bore cannula, and pause a few seconds before troubleshooting, bearing in mind that the flashback for EJV cannulation may take a little longer.

Costantino et al[28]demonstrated that while the EJV strategy had lower overall success rates compared to ultrasound-guided PIV (USG-PIV), success rates of both approaches among patients with visible EJV were similar. On the contrary, Witting et al[29]found EJV cannulation to be superior to USG-PIV, requiring fewer skin punctures, shorter operator time and having lower post-insertion failure.

Early escalation

Like all other invasive procedures, operator proficiency and experience matter for attaining PIVC success. Larsen et al[30]demonstrated that self-rated competence and experience correlate well with the likelihood of successful PIVC, while Lapostolle et al[1]likewise noted higher cannulation success rates in the hands of a more experienced operator. Early escalation to a more experienced operator upon recognition of DIVA is therefore prudent.

Hartman et al[31]found that creating a paediatric peripheral vascular access algorithm assisted early recognition of DIVA and helped prompt the decision to stop and escalate to trained specialists, reducing the overall number of attempts per patient. Similar escalation pathways were successfully implemented by Harrison et al[32]and Sou et al[7]in their respective institutions.

Certain centres have instituted a DIVA workflow which calls upon a specialized vascular access team to perform ultrasound-guided peripherally-inserted central catheter cannulation emergently.[33]Such a protocol would, however, require significant resources to muster and may inadvertently delay resuscitation until help arrives.

Augmenting venodilation

Tourniquet application

Tourniquets are nearly univers ally employed in venepuncture procedures and are considered the standardof-care for venodilation. Releasing and re-applying the tourniquet may further improve venodilation as blood flow through ischemic tissue releases histamine.[34]

1) Sphygmomanometer cuff

S o m e p h y s i c i a n s a d v o c a t e i n f l a t i n g a sphygmomanometer cuff to around diastolic blood pressure instead of using the traditional tourniquet to improve patient comfort and avoid traumatizing fragile veins.[35]Kule et al[36]reported that using a sphygmomanometer cuff decreased vein compressibility significantly and proved superior to tourniquets, but this was disputed by Nelson et al[37]and Tran et al.[38]These contradictions were explained by Sasaki who proposed that vein size paradoxically decreased once pressures exceeded 100 mmHg (1 mmHg=0.133 kPa),[39]presumably due to occluded arterial inflow. Sasaki’s theory is supported by Xiong et al[40]who demonstrated that 60-90 mmHg is the optimal inflation pressures.

Should one be using a sphygmomanometer cuff as a tourniquet, one ought to consider inverting it (such that the tubing runs proximally towards the upper arm) to avoid interference with access and getting blood on the cuff.[41]2) Double tourniquets

While Hadzic advocates using double and even triple tourniquets to yield better venodilation,[19]Price et al[42]did not find significant improvement in first-attempt success rates - although notably Rezaie had both tourniquets proximal while Price had one proximal and one distal. Some physicians suggest applying the tourniquets on top of each other rather than sequentially, while yet others propose doubletying a single tourniquet to achieve the same effect.A tourniquet prevents venous return while allowing arterial inflow, so the radial pulse should remain palpable regardless of tourniquet position.[43]

Wrap techniques

Hadzick devised a unique “reverse-Esmarch”technique that involves wrapping an Esmarch bandage circumferentially to milk blood proximal-to-distal into the dorsal and volar hand veins.[19]Wrap techniques might also be useful for oedematous patients, for whom one could elevate the limb first and squeeze out the edema with an elastic wrap before cannulation.[44]

Forced expiration

Villa et al[25]found significant increases in crosssectional basilic and brachial vein diameters following ten seconds of Valsalva manoeuvre compared to tourniquet application, suggesting that a properlyperformed Valsalva could augment venodilation in situations where tourniquet application is not possible(such as EJV cannulation, patients with fragile skin or patients who cannot tolerate tourniquet pain). Lewin et al[45]suggested having patients hum. This closed-mouth,forced-expiration technique increases intrathoracic pressure and distended veins as much as Valsalva and Trendelenburg position did.

Physical manoeuvres

Lowering the limb below the level of the heart promotes venous engorgement through gravitydependent pooling of venous blood. Yamagami et al[46]found that vessel dilation was significantly greater in the supine position instead of seated, including in DIVA patients. Isometric exercises such as clenching the fist several times can also enhance arterial inflow through compressive muscular pump activity[47]and through stimulation of muscarinic skin receptor-mediated vasodilation.[48]

Tapping potential sites vigorously while the tourniquet is applied releases vasoactive mediators like histamine and nitrous oxide from the vascular endothelium that render veins more prominent.[49]Slapping too hard, however, could cause pain and trigger autonomic-induced vasospasm.[50]Finally, one could milk the venous flow from proximal-to-distal to increase venous prominence.[51]

Topicals

While swabbing with topical alcohol or povidoneiodine[48]is meant to disinfect and cleanse the site, the change in light reflecting off the skin can also help improve vein visualization, especially in dark-skinned individuals.[49]Topical application of small aliquots of glyceryl trinitrate may also produce venodilation as well,but transdermal absorption can exacerbate tachycardia and hypotension.[52]

“Bier’s block”

While the clinician should always insert an appropriately-sized cannula wherever possible, some veins are too small to accommodate the large-bore PIVCs required to facilitate rapid fluid resuscitation or permit contrast administration for contrast-enhanced scans.Another useful strategy would be to apply a tourniquet on the limb, introduce a small-gauge catheter and infuse 50-100 mL of normal saline to markedly distend the veins to the point that a large-bore cannula can then be placed. Stein drew inspiration for this from Bier’s block procedure and published it in 2005,[52]but this method was described by Gemmell in 1984[53]and Kondo in 1996.[54]

Heat application

Heat application to induce vasodilation has been suggested, either via heat-packs, hot water baths or by placing the patient’s hand in a plastic bag and inserting the hose of a forced-air warming device.[55,56]While brief application might be safe, such off-label misuse of warming devices has resulted in thermal burns[57]and was highlighted in a 2002 Food and Drug Administration safety alert. Ray et al[58]suggested a simpler, safer and cost-effective method of having the patient put on a standard disposable glove for a brief period instead,using local warmth and constriction to help distend the dorsal hand veins.

Venodilation devices

The venous distension device, which creates a vacuum around the arm to augment venous filling, was deemed promising for DIVA in the 1980s[59]but failed to gain traction in popularity following the emergence of ultrasonography as a more definitive adjunct. Another device, Veinplicity, uses electrical stimulation to aid dilation of forearm veins. It was shown to improve first-attempt success rates in participants at moderate risk of DIVA[60]and induced more effective and longer venodilation than heat-packs.[61]However, such devices are not commonly available.

Vein visualization

Flushing cannula

A simple technique to obtain a faster flashback is to remove the back-cap of the cannula and flush the cannula with saline first. This pearl comes especially handy for paediatric PIVCs where the cannula is advanced over the needle as soon as flashback is encountered, instead of advancing the needle slightly more like in adults.[62,63]

Ultrasound guidance

Safe, quick and efficient, ultrasound-guided (USG)PIVC is a useful tool in the DIVA arsenal. Several metaanalyses found fairly consistent increase in cannulation success rates with USG in DIVA[64-68]but no benefit for routine use in non-DIVA patients.[69]USG permits realtime visualization of deep, large peripheral veins that cannot be palpated or visualized with the unaided eye.Ultrasound can also confirm vessel patency (based on compressibility) and verify successful cannula placement by visualizing the cannula tip within the lumen and observing tiny anechoic bubbles within the vessel upon saline flush.[70]

1) Probe handling

Mahler et al[71]demonstrated higher USG-PIVC success rates and shorter time required with a shortaxis/out-of-plane rather than long-axis/in-plane or oblique approach. A phantom model study confirmed that insertion times were halved with the short-axis approach,[71]while Blaivas found novice operators preferred the short-axis technique.[72]

Of course, learning and being versatile with both approaches is probably best - in addition, one would do well to consider incorporating these techniques with the“incremental advancement” technique. This involves following the needle-tip from the first puncture until intraluminal placement by slowly inching the probe away from the puncture point.[73]Tilting the probe slightly away from the operator (“heel-in”) to maintain a 90° angle with the advancing needle and jiggling the bevel of the needle-tip up-and-down can further accentuate the beam cast.[74]Confirmation of a freelymovable intraluminal needle-tip is critical as the needletip and shaft appear similar[75]and would even preclude the need to visualize a flashback (which does not always guarantee intraluminal placement[76]).

One should take heed to avoid pressing hard on the vein with the probe post-placement as this could dislodge the target vein and potentially draw the cannula out of the venous lumen.[77]Other simple USG-PIVC-related pearls include optimization of ergonomics by positioning the patient with elbow extended and forearm completely supinated[20]and placing the ultrasound machine next to the patient or on the contralateral side to maintain direct line of sight.[72]2) Target vein

Ideal target veins for USG-PIVC are superficial large veins greater than 4 mm in diameter,[78]as the odds ratio for successful cannulation improves by 1.79 for every millimetre increase in vessel.[79]Anterior forearm veins are optimal veins for USG-PIVC, in particular the cephalic vein which is relatively superficial, and the basilic vein which is typically not associated with an artery and too deep to be palpated or visualized otherwise.[80]In addition, one should focus on searching for veins within 16 mm in depth, as this was shown by Panebianco et al[79]to be the threshold depth beyond which no vessels could be successfully cannulated with standard-length cannulas.

3) Dual-operator technique

The utility of having an assistant handle the ultrasound probe while performing cannulation is controversial. Rose et al[81]found no difference in either overall success or time; but Costantino et al[2]cited a 97% first-attempt success rate (from 33%) and decreased time-to-insertion from 30 min to 13 min for emergency physicians. Chinnock et al[82]likewise noted improved success rates from 66% to 72% for nurse-initiated USGPIVC.

4) Catheter length

Dargin et al[83]and Elia et al[84]demonstrated that USG-PIVCs located in deep veins tend to dislodge easily in up to 45% and 56% of cannulations respectively, leading to phlebitis and extravasationrelated complications. Using long PIVCs (at least 8 cm in length), extended-dwell catheters or mid-lines can reduce dislodgement and increase catheter survival.[85]Indeed, Pandurangadu et al[86]showed that all cannulas failed when ＜30% of the cannula resided in the vessel(while none failed if two-thirds length was intravascular)and recommended ensuring at least 65% of any cannula dwell within the vein. This would necessitate advancing at a steeper angle (30-45 degrees) if targeting deep veins while utilizing standard-length cannulas (as the same length has to transverse through more soft tissue by Pythagoras theorem[87]), bearing in mind that a steeper angle would in turn pose a higher risk of inadvertent through-and-through back-wall perforation.

Mid-lines

Some centres advocate employing “mid-lines” - long peripheral catheters ranging 7.5-25.0 cm in length[88]- instead of standard PIVCs if vascular access is required for longer than five days.[89]Mid-lines typically terminate in the basilic or cephalic vein just short of the subclavian vein[90]and are traditionally differentiated from long PIVCs by their tip location as confirmed by radiography,[91]but this distinction is not universally adopted.

Mid-lines offer the advantage of providing more definitive venous access than conventional USG-PIVCs,allowing longer dwell time and permitting vasopressor or inotrope infusion,[88]albeit with the trade-off of requiring longer time to cannulate than PIVCs as line placement is done with full sterile precautions similar to CVCs.[84]While most mid-lines are typically placed under USG,mid-lines should be considered a unique strategy in their own right as insertion can be performed via direct Seldinger technique without USG[92]or by sterile overwire exchange of an existing PIVC.

Near-infrared technology

Another method of vein visualization that has gained prominence in recent years is near-infrared vein-finder technology, which utilizes the principle of selective absorption of near-infrared waves by deoxyhaemoglobin to display a venous road-map of superficial veins.[93]While these devices do not demand much technical expertise unlike ultrasonography, they do not demonstrate depth and can not detect deep veins well as they are limited in range to 8-10 mL.[93]Conflicting results have been reported about the impact of nearinfrared technology on first-attempt success and total procedural time.[94]Vein-finders are thus best reserved for confirming the direction in which poorly-visualized veins run to guide the approach trajectory.

Trans-illumination

Pen torches[95], red bicycle lights[96]and even the mobile phone flashlight[97]can be utilized as cheap,readily-available alternatives to commercial instruments designed for trans-illuminating superficial hand veins that are otherwise invisible to the naked eye. While mostly used for paediatric vascular access as neonates have less soft tissue, Cai et al[95]found that trans-illumination is also useful for adults and can help one avoid branch points, valves and thrombosed and tortuous veins more easily.

Alternative routes

“Easy-IJ”

Placing a standard peripheral catheter in the internal jugular vein (IJV) was proposed as an alternative to formal CVC.[98]Dubbed the “easy-IJ” as it does not require a fully sterile technique. Moayedi et al[99]established this as a safe and faster means of establishing temporary vascular access if USG-PIVC and EJV cannulation have failed. In a study by Zitek et al,[100]“easy-IJ” was successful in 97.1%of patients and took only 3 min on average while CVC insertion took 20 min.[29]Importantly, no pneumothorax,arterial puncture or line-related sepsis were encountered despite full sterile precautions for only eight of 34 lines.[101]“Easy-IJ”can also be subsequently converted into a formal central line via the Seldinger technique.[101]

However, “easy-IJ” use ought to be limited to 24 h or once alternative, and more definitive vascular access can be established owing to the risk of catheter-related bloodstream infection of a central vein.[99]The safety of vasopressor administration through the “easy-IJ” has also not been evaluated and is not recommended out of caution.[102]

Central venous cannulation

CVC remains the default strategy for stable DIVA patients who have exhausted other options. However,CVCs are invasive, take a longer time to insert, and are associated with a small but significant risk of serious complications.[103,104]Indeed, most researchers began advocating for alternative DIVA strategies to minimize the need for unnecessary CVCs. Poiseuille’s law dictates that fluid flow is determined by viscosity, pressure gradient, length and diameter of the tubing,[105]flow rates of standard CVCs are therefore significantly slower than large-bore PIVCs[105]and this may limit aggressiveness of fluid resuscitation in an emergency.

Intraosseous access

Most clinical practice guidelines advocate use of intraosseous access in cardiac arrest and for patients in extremis or decompensated shock if other attempts at vascular access fail or take longer than 90 s.[106]As intraosseous access can be achieved expediently in as little as four seconds,[107]one should be prepared to escalate to intraosseous access early for DIVA patients in extremis.

Venous cut-down

Once a mainstay of resuscitation and taught as part of Advanced Trauma Life Support,[108]venous cut-down has fallen out of favour with the advent of other comparatively less-invasive modalities such as intraosseous access and USG. As venous cut-down demands considerable time, operator expertise and may cause serious vascular injury if performed erroneously, it is rarely practiced in well-resourced healthcare systems currently.[109]

Customised catheters

Other adjunct tools that could help overcome DIVA include specially-designed PIVCs. Raio et al[110]found excellent results with a novel intravascular catheter system with a retractable coiled-tip guidewire (BD’s AccuCath). The coiled-tip guidewire purportedly allows navigation through tortuous vessel anatomy without having to advancing the needle more than necessarily.While van Loon et al[111]also demonstrated success with a similarly notched PIVC, such proprietary devices are typically not available to the operator.

Montrief et al[112]found that using micropuncture kits reduced bleeding and other complications whilst improving cannulation first-attempt success rates. These kits utilize a small-bore needle to obtain initial access,microwire to facilitate rail-roading via a modified Seldinger technique, dilator and introducer sheath. The small micropuncture needle affords a larger margin of safety and reduces likelihood of accidental backwall perforation, while its echogenicity permits easy sonographic visualization of the needle-tip.[113]

Post-insertion care

Requiring repeated cannulation attempts because of unnecessary dislodgement following successful placement is extremely frustrating and distressing for medical staff, patients and their caregivers.[114]Properly securing the vascular access lifeline of a DIVA patient is even more challenging yet vital if the patient is diaphoretic or agitated and uncooperative, since USGPIVCs in deep veins have shorter intra-luminal lengths and are at higher risk of dislodgement.

Budgen et al[115]found that in addition to standard securement methods, a drop of skin-adhesive glue under the catheter hub reduced the failure rates of emergency department-inserted PIVCs. Most adhesive dressing films used to secure cannulas do not work well if the patient is diaphoretic or wet.[116]One would therefore have to wipe away existing sweat and apply a firm cotton bandage beneath the dressing to increase friction and wick away moisture.[117]“Under-and-over” taping has also been shown to provide more security.[118]If utilizing flexural sites (like the finger or wrist), one may have to splint the joint to prevent dislodgement.[119]Last, it is a good practice for one to document that the patient has DIVA as this alerts subsequent healthcare providers and may impact future management.

Special situations

Burns

Peripheral and central catheter-related infections affect 8%-57% of burn patients, leading to sepsis and bacteremia.[120]Intravenous access should be established in burn patients as early as possible before oedema forms. This should preferably be through unburned intact skin, although this could be through burned skin if necessary to avoid delays to resuscitation.[121]Suturing or stapling catheters to skin may help, as tape does not adhere well to burned skin and circumferential taping across extremities may also cause ischemia.[122]Lines through eschar ought to be monitored carefully and replaced within 72 h, beyond which colonization and infection may set in.[123]For patients with extensive burns or inhalational injury, central venous access is typically required to facilitate hemodynamic monitoring and sustained treatment with large-volume fluids or vasoactive drugs.[124]

Breast cancer

Most authorities such as the Association of Anaesthetists of Great Britain and Ireland (AAGBI)[125]advise patients who have undergone axillary lymphatic dissection for breast cancer to avoid venepuncture or cannulation on the ipsilateral arm as this might lead to lymphedema and cellulitis. Although Ferguson et al[126]enrolled 632 patients prospectively and discovered no such association, while Jakes et al[127]likewise found no good evidence to support such avoidance. The AAGBI cited a small-but-persistent risk of triggering late-onset lymphedema and advocated avoidance “except in acute situations”.[128]Therefore, although one should still keep clear of the at-risk limb wherever possible, short-term cannulation performed under aseptic conditions for an acutely-ill DIVA patient is defensible given the limited literature available.

End-stage kidney disease

Peripheral and central venous cannulation can cause local inflammation and endothelial damage leading to scarring and thrombosis that preclude future arteriovenous fistula creation.[129]For patients with chronic kidney disease stage 3B or greater, the Michigan Appropriateness Guide for Intravenous Catheters(MAGIC) recommends PIVC placement preferentially in the dorsal veins of the dominant hand, while dorsal veins of the non-dominant hand are second-line because arteriovenous fistulas are typically created on the nondominant limb first.[90]The large forearm or upper arm veins should be used only as a last resort to preserve the peripheral and central vasculature for future haemodialysis needs.[130]The cannulation site should also be rotated if possible to minimize venous scarring.[131]

Algorithm

We propose a stepwise approach to DIVA that is modelled after the Vortex approach to the difficult airway popularized by Chrimes[132](Figure 1).

The Vortex approach is based on the same premise that attempts to establish emergency vascular access should start off with standard PIVC techniques first and progress sequentially to USG-PIVC and CVC,before resorting to the most invasive intraosseous route only if the patient is in extremis or if the other lifelines prove futile. Unlike Chrimes’ Difficult Airway Vortex which describes an outer green zone where the patient spontaneously maintains ventilation,[132]the DIVA Vortex lacks an outer green zone as vascular access would not be immediately available without intervention from the operator.

Progression further along the algorithm also demands increasingly sophisticated resources - from near-infrared vein-finders to ultrasound and progressing eventually to requirement of full aseptic conditions for CVC. The initial first-line strategies would therefore be most relevant to operators working in austere or out-ofhospital low-resource settings (Figure 2).

Figure 1. Difficult intravenous access (DIVA) Vortex. IV: intravenous.

Figure 2. Difficult intravenous access (DIVA)Vortex (expanded). NIR: near-infrared; IJ: internal jugular.

Decisions on which lifeline to adopt also invariably depend on the patient’s acuity, the operator’s expertise and the availability of the required equipment. When attending to collapsed or critically ill patients in extremis who are known to have DIVA (in particular those with prior documentation of DIVA as assessed by an experienced healthcare provider), one should consider attempting intraosseous insertion immediately to achieve rapid access if intraosseous equipment can be made readily at hand. Alternatively, one could consider a “double set-up” in time-critical cases where one operator attempts PIVC while another operator prepares,landmarks and stands by to proceed with intraosseous access once PIVC has failed.

CONCLUSION

DIVA is a perennial problem that healthcare providers across varied disciplines will always encounter,and the rising global obesity epidemic will only make it more relevant. It is crucial to have a systematic stepwise approach such as the DIVA Vortex when managing such patients and have at hand a wide repertoire of techniques to draw upon.

Funding:This work received no funding or financial support.

Ethical approval:No ethical approval was sought from Institutional Review Board because this is a review article involving the study of publicly available data and does not directly involve any individual human participants, human biological material or individually-identifiable health information.

Conflicts of interest:The authors have no conflicts of interest to disclose.

Contributors:MN and LF conceived the study concept and design. MN was involved in study retrieval and analysis, while LKFM and LF were involved in the drafting and critical revision of the manuscript.