IV cannulation is one of the most commonly performed medical procedures in the United States, performed by many healthcare providers including physicians, nurses, and first responders. IVs are used for quickly administering fluids and medications in emergency situations, in the operative setting, and in patients who cannot tolerate oral intake. Despite its prevalence as a procedure, it is not a universally successful one. Some cannulations require multiple attempts, which increases the cost of the procedure with more procedure kits used and the likelihood of adverse events such as pneumothorax, arterial puncture, and nerve injury. There are many patient factors that influence whether an IV cannulation will be difficult, including body habitus, clinical experience of the provider, and clinical judgment of the visibility or palpation of peripheral veins.  

Body habitus can influence ease of IV cannulation. In a 2013 prospective study evaluating IV cannulation in 563 adult patients in the emergency room, physicians and nurses had difficulty with peripheral vein access in 21% of the attempts, defined as needing more than 1 attempt for successful vein access.¹ Risk factors for difficult access included BMI >30 and <18.5, suggesting that IV cannulation may be more difficult in overweight and underweight patients. Another factor associated with difficult access was an unfavorable clinician assessment of peripheral vein access which included difficulty visualizing or palpating peripheral veins. 

Clinical experience is another influencing factor of IV cannulation success. In a 2005 prospective study analyzing 339 IV insertions in hospitalized patients, nurses were observed placing IVs.² 77% of the IVs inserted were successful on the first attempt, and first attempt success was associated with nurses who were older, had more years of clinical experience, and rated themselves highly on insertion skill. Failed IV insertions were associated with veins moving or being resistant to puncture and patient movement. 

If a difficult IV cannulation is anticipated based on the above factors, there are different options for approaching the procedure depending on the clinical scenario. If there is an emergent need for IV access, such as fluid resuscitation in trauma, intraosseous cannulation may be used, which is inserting a catheter into the veins of the medullary sinuses in long bones. Typically, intraosseous cannulation is not first line due to the invasiveness and pain associated with the procedure. Intraosseous cannulation is most commonly used in children requiring fluid resuscitation. In non-emergent scenarios, if the facility has appropriate equipment, ultrasound guided IV is a viable option for gaining access. Ultrasound can be used to identify an appropriate vein and check the location of the catheter.³ It is also useful after the IV is placed to determine positioning and complications such as hematomas.³  

Another less common solution is to have a dedicated IV therapy team that is utilized for patients with difficult IV access. In a randomized control trial analyzing differences in complications with IVs inserted by residents and nurses and IVs inserted by a dedicated IV therapy team, IVs inserted by residents and nurses were found to have more signs and symptoms of inflammation at 21.7% while the IV therapy team only had 7.9%.⁴ While dedicated IV teams are not available at every hospital, this study suggests they are an useful and effective resource if available.  

Difficulty of IV cannulation is influenced by a multitude of factors including patient characteristics like body habitus and provider characteristics like experience with IVs. There are options for gaining venous access if there is unsuccessful peripheral vein access such as intraosseous access, ultrasound guided IVs, and a dedicated IV therapy team.  

References 

1. Sebbane M, Claret PG, Lefebvre S, Mercier G, Rubenovitch J, Jreige R, Eledjam JJ, de La Coussaye JE. Predicting peripheral venous access difficulty in the emergency department using body mass index and a clinical evaluation of venous accessibility. J Emerg Med. 2013 Feb;44(2):299-305. doi: 10.1016/j.jemermed.2012.07.051. Epub 2012 Sep 13. PMID: 22981661. 
2. Jacobson AF, Winslow EH. Variables influencing intravenous catheter insertion difficulty and failure: an analysis of 339 intravenous catheter insertions. Heart Lung. 2005 Sep-Oct;34(5):345-59. doi: 10.1016/j.hrtlng.2005.04.002. PMID: 16157191. 
3. Kim SC, Heinze I, Schmiedel A, Baumgarten G, Knuefermann P, Hoeft A, Weber S. Ultrasound confirmation of central venous catheter position via a right supraclavicular fossa view using a microconvex probe: an observational pilot study. Eur J Anaesthesiol. 2015 Jan;32(1):29-36. doi: 10.1097/EJA.0000000000000042. PMID: 24384583. 
4. Soifer NE, Borzak S, Edlin BR, Weinstein RA. Prevention of peripheral venous catheter complications with an intravenous therapy team: a randomized controlled trial. Arch Intern Med. 1998 Mar 9;158(5):473-7. doi: 10.1001/archinte.158.5.473. PMID: 9508225.