“Blind” Access
It has been estimated that up to 30% of pediatric patients may require more than one attempt for IV access. A study by Cuper el al found that age and gender are significant predictors of difficult IV cannulation in the operating room, but body mass index (BMI) was not predictive. However, previous research by Nafiu et al found that obesity was also a predictor of difficult IV cannulation. While the use of ultrasound guidance is considered superior for IV access, particularly in difficult cases, there are still some predictable locations for finding peripheral intravenous access in both the upper and lower extremities without the use of imaging. Below is a summary of these predictable locations and the evidence supporting their use.
Hand/Wrist
Dorsal Metacarpal Veins
While the "intern" and saphenous veins are fan favorites, one of my old attendings from fellowship (AM, thanks!) taught me that there are usually at least a couple of nice options situated between metacarpals on the dorsum of the hand. While they may not always be present, I’ve certainly had consistent success using this technique.
The dorsal metacarpal veins are veins located between the metacarpal bones on the top of the hand. In a study by Elmerghi et al,, researchers found that these veins typically follow predictable patterns and remain stable throughout adulthood. The study also found evidence of sexual dimorphism and ethnic variation in the patterns of these veins. If cannulation of these veins is difficult, switching to the opposite hand may be easier, as there is a 74% chance that the veins on the opposite hand have a more predictable pattern.
Now that we have established that dorsal veins seem to follow similar patterns, where should we stick?
A study by Salameh et al looked at the most prominent veins in the dorsal metacarpal area. The study used an infrared vein illumination system to identify the veins that were straighter and had fewer communicating veins. The researchers found that the most prominent veins were typically located in the third and fourth intermetacarpal spaces. These veins are often the most accessible for venipuncture.
It is important to mention that the dorsal MCVs on the lateral side of the dorsum of the hand coming from the first and second metacarpal spaces were usually involved in the formation of the radial group of veins that form the cephalic vein, commonly referred to as the “intern vein.”
So where to stick? It would seem that the 3rd and 4th intermetacarpal spaces would be your best bet.
(I myself am B and BB, with nice straight dominant veins in the 4th intermetacarpal space if you ever need to get “blind” access on me).
Cephalic Vein aka the “Intern Vein”
Anatomic Snuffbox
One cannot talk about the Cephalic Vein (CV) in the distal forearm without a brief description of the Anatomical Snuffbox. The anatomical snuffbox is a triangular depression found on the lateral aspect of the dorsum of the hand. It is located at the level of the carpal bones, and best seen when the thumb is extended and abducted. Its name was derived from using the depression as a means of placement for the inhalation of powdered tobacco, otherwise known as dry snuff, and was first described in the medical literature in 1850.
The anatomical snuffbox is bordered medially by the tendons of the extensor pollicis longus and laterally by the tendons of the extensor pollicis brevis and the abductor pollicis longus. The base is formed by the styloid process of the radius. Three vital structures are contained within the anatomical snuffbox: the radial artery, the superficial branches of the radial nerve, and the cephalic vein. The CV is formed when the dorsal digital vein from the radial side of the index finger and the two dorsal digital veins of the thumb join each other.
Though this has been evaluated in cadavers, Salameh et al sought to study the formation of the Cephalic Vein (CV) in relation to the anatomic snuffbox in live Jordanian subjects. They evaluated 438 subjects for a total of 722 hands using an infrared illumination system.
They found 4 general patterns, with the CV forming either proximally or distally, and either inside or outside the anatomical snuffbox. The most common site of CV formation in both genders was inside the proximal anatomical snuffbox. While this same pattern was also most common in right hands, the most common in left hands was distal and outside. Though there was some heterogeneity across gender and sidedness, the CV was still found in the anatomical snuffbox in 98% of the examined hands, regardless of its origination location. This is reassuring given the frequency of CV cannulation in this location.
Adapted from Salameh, M.A., Shatarat, A.T., Badran, D.H., Abeeleh, M.A., Kanaan, T.M., Bani-Hani, A.M. and Hamdan, M.Q., 2021. Revisiting the anatomy of the cephalic vein, its origin, course and possible clinical correlations in relation to the anatomical snuffbox among Jordanian. Folia morphologica, 80(2), pp.344-351.
Despite this predictability, cannulating the CV in the anatomical snuffbox is not without risk. Both the Radial Artery (RA) and the Superficial Branch of the Radial Nerve (SBRN) also traverse the anatomical snuffbox and care must be taken not to injure either structure. The RA typically passes deep to the tendons of the Extensor Pollicus Brevis and Abductor Pollicus Longus as it enters the anatomical snuffbox, eventually passing deep to the tendon of the Extensor Pollicus Longus. Although this course is fairly reliable, at least two variations have been identified. In the first class, the RA is single and is entirely superficial to the tendons of the anatomical snuff box. In the second class, documented as duplication of the RA, the RA divides into superficial and deep branches. Though the estimated incidence is quite low (~1.3%), one must take care care not to accidentally cannulate the artery in it’s new superficial course.
A few studies have looked at the relationship of the SBRN and CV. Vialle et al examined 33 cadaveric forearms and wrists. They found the intersection between CV and SBRN occured in highly variable positions. In each specimen, the nerve crossed the inferior face of the CV or one of its tributaries at least once, in 42% the nerve and vein crossed in two different places, and in one case, they crossed three times! Though the SBRN appears to be reliably posterior to the CV, it appears that it is reliably posterior to the vein, you just never know where!
These findings were consistent with both Robson et al and Samarakoon et al who found that the CV was closely related (<2 mm) with the SBRN in 80% of cases, and that the CV and the SBRN crossed each other at least once, and even twice, respectively. Because of these findings Vialle et al recommend CV cannulation at least 12cm proximal from the styloid process of the radius, or a little under half the forearm length from the wrist to the elbow.
If you are going to attempt cannulation of the “Intern Vein” in the anatomical snuffbox, be mindful. Palpate first to make sure it isn’t the RA and take care not to pierce the back wall. Odds are, you might be dancing right on top of the SBRN!
Antecubital Fossa
In a study conducted by Lam et al, the cephalic vein (CV) was examined in 100 infants between the ages of 0 and 1 year. The point of location (POL), or where the vein was at its largest on ultrasound, was determined. The distance of the cephalic vein from the lateral edge of the upper arm and its location in relation to the antecubital fossa were also calculated, as well as the mean depth and vessel diameter.
The results showed that the CV was in the same location in 84% of patients bilaterally. The mean distance from the lateral edge to the POL was 1/3 of the arm's width from the lateral border, and the mean distance from the antecubital fossa (AC) to the POL was 1/5 of the length of the upper arm to the AC. The mean depth was 0.4 ± 0.2 cm bilaterally, and the mean diameter was 0.2-0.25 ± 0.13, which is typically large enough to accommodate a 22-g or 24-g angiocatheter.
Measuring the upper arm into 1/5th's can be difficult, but one shortcut is to place your hand on the upper arm with your fingers evenly spaced between the antecubital fossa and the end of the upper arm. The next digit cephalad from the AC will be the presumed 1/5th plane. The authors also suggest entering the skin at the presumed POL and advancing the needle towards the shoulder. If no blood appears in the angiocatheter after advancing the needle 0.5 cm, the angiocatheter should be incrementally redirected medially.
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body
Saphenous
In my mind, there is almost no greater sense of satisfaction than effortlessly and slickly sliding in IV in the saphenous blindly, especially after everyone else has reached their breaking point. The Great Saphenous Vein (GSV)—a large, subcutaneous, superficial vein of the leg—is actually the longest vein in the body, running along the length of the lower limb, returning blood from the foot, leg and thigh to the deep femoral vein at the femoral triangle. The GSV is commonly cannulated at the ankle using anatomical landmarks or palpation. The classic teaching is that the GSV always runs just anteriorly to the medial malleolus, roughly 1 cm anterior and 1 cm superior to the medial malleolus. Though, that may not actually be the case.
In a study conducted by Germino et al, the accuracy of the landmark technique for cannulating the great saphenous vein (GSV) was assessed. The study included 100 participants between the ages of 3 and 16 years old. After identifying the GSV on ultrasound, the distance from the landmark site to the nearest edge of the GSV was recorded, as well as its relative location to the landmark site. The landmark technique was deemed accurate if any part of the GSV lumen was found directly beneath the landmark site.
The results showed that the GSV was found at the predicted location in only 17.5% of cases. This number decreased to 4.9% for participants under the age of 10. Additionally, all participants had at least one visible GSV, but in about 7 out of 200 legs, no visible vein was found. The mean distance from the predicted to the actual GSV location was around 5mm.
Given the poor accuracy of the proposed landmark (o), with the true location of the GSV almost always closer to the medial malleolus, the authors proposed a new landmark (n) at 5 mm anterior and 5 mm superior to the medial malleolus. After applying this new predicted location to their data set, they found an overall accuracy of 26.5%, with the biggest improvement in the youngest patients. In kids under 10, the accuracy of the landmark technique improved from 4.9% to 24.5%, a fivefold increase in accuracy.
In another study conducted by Joshi et al, the use of landmark versus ultrasound techniques for cannulating the great saphenous vein (GSV) in children between the ages of 6 months and 2 years was evaluated. The study also compared the success rates of trainees to those of pediatric anesthesiologists. Prior to scanning, the practitioners marked the intended puncture site of the GSV bilaterally at the ankle based on anatomical landmarks.
The results showed that the use of the landmark technique for GSV cannulation would have resulted in a failure rate of 73% if the puncture site was made at the marked site. Furthermore, experience in pediatric anesthesia only slightly improved the success rate from 22% to 33%.
This should come as no surprise, but it appears as if the moral of the story is ultrasound reigns supreme. If you’re truly going for a “blind” attempt—vein not visualized or palpable—the likelihood of successful cannulation pales in comparison to an ultrasound-guided technique. Unless you don’t have immediate access to one, make your life a whole lot easier and grab an ultrasound.
Cuper, N.J., De Graaff, J.C., Van Dijk, A.T., Verdaasdonk, R.M., Van Der Werff, D.B. and Kalkman, C.J., 2012. Predictive factors for difficult intravenous cannulation in pediatric patients at a tertiary pediatric hospital. Pediatric Anesthesia, 22(3), pp.223-229.
Nafiu, O.O., Burke, C., Cowan, A., Tutuo, N., Maclean, S. and Tremper, K.K., 2010. Comparing peripheral venous access between obese and normal weight children. Pediatric Anesthesia, 20(2), pp.172-176.
Salameh, M.A., Shatarat, A.T., Badran, D.H., Abu-Abeeleh, M.A., Massad, I.M. and Bani-Hani, A.M., 2019. The best vein to be accessed based on descriptive study of dorsal metacarpal vein. Anatomy & cell biology, 52(4), pp.390-396.
Elmegarhi, S.S., Amarin, J.Z., Hadidi, M.T., Badran, D.H., Massad, I.M., Bani-Hani, A.M. and Shatarat, A.T., 2018. Dorsal metacarpal veins: anatomic variation and potential clinical implications. Anatomical science international, 93(2), pp.238-243.
Salameh, M.A., Shatarat, A.T., Badran, D.H., Abeeleh, M.A., Kanaan, T.M., Bani-Hani, A.M. and Hamdan, M.Q., 2021. Revisiting the anatomy of the cephalic vein, its origin, course and possible clinical correlations in relation to the anatomical snuffbox among Jordanian. Folia morphologica, 80(2), pp.344-351.
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Vialle R, Pietin-Vialle C, Cronier P, Brillu C, Villapadierna F, Mercier P. Anatomic relations between the cephalic vein and the sensory branches of the radial nerve: How can nerve lesions during vein puncture be prevented? Anesth Analg. 2001 Oct;93(4):1058-61
Samarakoon, L.B., Lakmal, K.C., Thillainathan, S., Bataduwaarachchi, V.R., Anthony, D.J. and Jayasekara, R.W., 2011. Anatomical relations of the superficial sensory branches of the radial nerve: a cadaveric study with clinical implications. Patient safety in surgery, 5(1), pp.1-6.
Robson, A.J., See, M.S. and Ellis, H., 2008. Applied anatomy of the superficial branch of the radial nerve. Clinical Anatomy, 21(1), pp.38-45.
Lam HV, Nyshadham S, Edney J, Austin T. Characterizing the cephalic vein as a blind cannulation target in infants. Paediatr Anaesth. 2020 Jul;30(7):838-839.
Hanada, S., Van Winkle, M.T., Subramani, S. and Ueda, K., 2017. Dynamic ultrasound‐guided short‐axis needle tip navigation technique vs. landmark technique for difficult saphenous vein access in children: a randomised study. Anaesthesia, 72(12), pp.1508-1515.
Triffterer, L., Marhofer, P., Willschke, H., Machata, A.M., Reichel, G., Benkoe, T. and Kettner, S.C., 2012. Ultrasound-guided cannulation of the great saphenous vein at the ankle in infants. British journal of anaesthesia, 108(2), pp.290-294.
Tu, Z., Tan, Y., Liu, L., Xie, J., Xu, Y. and Liu, W., 2021. Ultrasound-Guided Cannulation of the Great Saphenous Vein in Neonates: A Randomized Study. American Journal of Perinatology.
Joshi, M., Wilson, G. and Engelhardt, T., 2010. Comparison of landmark technique and ultrasound guidance for localisation of long saphenous vein in infants and children. Emergency Medicine Journal, 27(6), pp.443-445.