The 3 Stations of the Needle: A systematic approach for ultrasound guided venous and arterial puncture

Abstract

Point-of-care ultrasound-guided (POCUS) venous and arterial access involves accurately guiding a needle from the skin surface through subcutaneous tissue to the target vessel. The success of this procedure relies heavily on the operator’s ability to locate and direct the needle tip, which can lead to multiple puncture attempts and iatrogenic complications. A literature review revealed a lack of comprehensive protocols addressing the sonographic details necessary for effective needle identification and vessel cannulation. This paper presents a systematic approach, the “3 Stations of the Needle” protocol, which includes: (1) identifying the needle after initial skin puncture within the subcutaneous tissue; (2) navigating the needle to the vessel’s outer wall; and (3) advancing the needle tip into the vessel lumen. This protocol offers a practical educational method for an ultrasound mastery learning program, enhancing needle identification, guidance, safety, and procedural success in venous and arterial cannulation.

Keywords

Arterial catheterization central venous catheterization needle visualization patient safety peripheral vein catheterization ultrasound guidance

Introduction

Over the past two decades, the use of point-of-care ultrasound (POCUS) for vascular access has significantly improved the safety and efficacy of one of the most commonly performed invasive procedures in healthcare. Initially, POCUS was employed to enhance central venous access, effectively reducing the risk of iatrogenic complications (e.g. nerve damage, hematomas, inadvertent arterial punctures, pseudoaneurysms, and pneumothorax or hemothorax) linked to traditional blind anatomical needle techniques. This advancement in patient safety rapidly became the standard of care, supported and endorsed by various professional organizations.^1–6 Today, evidence continues to grow, supporting the use of POCUS for venous and arterial cannulation.^7,8

While ultrasound has significantly reduced morbidity and mortality associated with large-caliber vascular access, its application to smaller-caliber peripheral venous and arterial vessels remains challenging across all patient populations. Procedures guided by needle POCUS can be complex due to the anatomical variations of both superficial and deep vessels. This complexity often leads to complications such as failed attempts, hematomas, pseudoaneurysms, nerve damage, inadequate catheter placement, and subsequent infiltration and extravasation.^9,10 It is well established that multiple factors influence fine motor procedural success.

Locating and guiding the needle tip into a vein or artery using ultrasound is crucial for accessing challenging patients. Standardized training approaches that effectively measure and document competency and success are essential to ensure patient safety during these procedures. The Infusion Nurses Society (INS) Standards of Practice, the Association for Vascular Access, the Italian Group of Venous Access Devices (GAVeCeLT), and the Society of Critical Care Medicine (SCCM) all recommend developing a comprehensive ultrasound-guided training program that supports clinicians progressing from novice to competent expert, enhancing their skills and confidence in performing these vital procedures.^11–14

Standardized assessment and insertion protocols for ultrasound-guided vascular access of peripheral, central and arterial pathways (Safe Insertion of Arterial Catheters (SIA), Rapid Peripheral Vein Assessment (RaPeVA), Rapid Central Vein Assessment (RaCeVA), Rapid Femoral Vein Assessment (RaFeVA), Safe Insertion of PICCs (SIP), Safe Insertion of Centrally Inserted Central Catheters (SIC), Safe Insertion of Femorally Inserted Central Catheters (SIF)) are available.^15–21 Key concepts related to these protocols, including the relationship of the needle to the ultrasound probe; the identification of the echogenic needle tip in the acoustic windows of the transverse, longitudinal, and oblique axis; the triangular trajectory approach, and the intravenous “walking of the needle” have been well described in the literature.^22–24 The procedural literature reveals a significant gap: the lack of a detailed sonographic protocol that thoroughly addresses the crucial phase of needle identification following skin puncture up to vessel cannulation. This critical phase of the insertion process, referred to as the 3 Stations of the Needle, enhances successful vessel cannulation and avoids iatrogenic complications (Table 1).²⁵

Table 1.

3-Stations of the Needle.

Stations of the needle	Description	Key points
1	Identification of the needle tip upon skin entry to the subcutaneous tissue	Procedural time out confirming needle trajectory and depth of vessel before advancement of the needle
2	Navigation of needle tip from the subcutaneous tissue to outer wall of target vessel	Procedural time out for assessment of the surrounding structures of the intended target vessel for safe needle navigation using the PN-T
3	Vessel confirmation (arterial or venous) and needle advancement through vessel walls	Procedural time out before vessel puncture and P-NT for vessel purchase

P-NT: probe-needle technique.

Used with permission of authors.

Ultrasound-guided vascular access training programs that use validated mastery learning strategies emphasize needle guidance to improve clinical outcomes.^26–29 Bloom first described the mastery learning approach as an instructional strategy in which students must achieve and demonstrate a level of mastery for knowledge and performance.²⁶ This mastery learning is achieved through a systematic process that breaks down complex skills into smaller, more manageable steps. Although mastery learning for ultrasound-guided needle insertions is well-documented in the literature, there is limited guidance on practical program implementation.²⁸

3 Stations of the Needle

The 3 Stations of the Needle technique is a staged approach with hard stops designed to promote first attempt accuracy and success, prevent the operator from rapidly advancing the needle tip before its identification, and reinforce the safety concept of ultrasound guidance (Table 1). Specifically, this approach provides (1) identification of the needle tip within the subcutaneous tissue upon skin entry before advancement; (2) a systematic approach to ultrasound-led needle guidance from the subcutaneous tissue to the outer vein wall providing the ability for needle redirection, retraction, or procedural termination; (3) a final safety assessment by performing a “procedural time out” before vessel cannulation to confirm venous versus arterial; (4) the ability to position the needle at the center of the outer wall of the vessel before puncture; (5) to slowly and accurately advance the needle tip, or needle with catheter using simultaneous micro-movements (probe and needle) avoiding contact with the posterior wall of the vessel to ensure successful catheter or guidewire deployment.

Station 1

POCUS identification of the needle tip within the subcutaneous tissue

Station 1 describes POCUS identification of the needle tip within the subcutaneous tissue immediately following the initial skin puncture at 1–5 mm depth. Ultrasound visualization of the needle tip is achieved in the bevel-up position and appears as a bright hyperechoic structure, sometimes referred to as a star sign.^27,28,30 At this point of the procedure, the operator can assess the angle of insertion, trajectory, and length of the device required to achieve a 2/3 catheter purchase to the vessel. Adequate vessel purchase using a straight needle depends on its length, while adequate vessel purchase using a catheter is recommended to have 2/3 of its length within the vessel.³¹

Early needle tip identification allows the operator to adjust the trajectory toward the target through retraction and angulation. When retracting the needle, the ultrasound probe should be moved in sync in a retrograde fashion, maintaining visualization of the needle tip. In situations where repositioning the needle requires a sharp angle, it should be removed and a new approach performed. Obstacles to successfully identifying Station 1 include subcutaneous emphysema, edema, existing hematoma (from a previous attempt), and thick connective tissue.

Station 2

POCUS guidance of the needle from the subcutaneous tissue to the vessel wall

Station 2 describes the needle movement from identification within the subcutaneous tissue to the outer wall of the target vessel. This distance can be short when approaching superficial vessels (<2–3 mm) or extended (4–7 cm) with deep vasculature or subcutaneous needle tunneling. The space is navigated using micro-movements of the ultrasound probe proximally toward the vessel until the “star sign” fades, followed by needle movement to re-establish the “star sign.” This is referred to as the Probe-Needle Technique (P-NT). The P-NT is most effectively performed in the short (out-of-plane) and oblique axis, allowing for visualization and avoidance of the surrounding structures such as nerve, artery, muscle, collateral vessels, lymph, and the pleural lining. This P-NT technique is repeated until the hyperechoic needle tip is visualized, resting on the outside border of the intended target vessel, completing Station 2. Obstacles to successfully navigating Station 2 include needle angle, irregular or deep respirations/cough, patient movement, a drop in vessel depth, a nerve bundle, and an inability to locate the needle tip. If the needle tip cannot be successfully tracked, it should be removed. This built-in visual safety stop prevents iatrogenic complications.

Station 3

POCUS vessel confirmation and needle advancement through the vessel wall

Station 3 provides an intraprocedural time-out before vessel puncture. This phase begins with an assessment of the target vessel using compression to confirm a venous or arterial structure. The structures surrounding the posterior wall of the vessel, such as the artery, nerve bundle, or lung pleura, are noted.

Using the P-NT, the needle is guided slowly through the layers of the vessel walls until the bevel becomes visible. At this point, the insertion angle must be lowered to prevent puncture of the back wall of the vessel. The P-NT is continued to advance the needle/catheter 1–2 cm past the vein wall. The protocol concludes with observing blood return (via catheter or aspiration), followed by successfully placing a guide wire or deploying a catheter to the vessel. These visualization and simulation training methods and steps of needle guidance apply to venous, arterial and all patient populations.^32–36

Discussion

The 3 Stations of the Needle protocol POCUS method for vascular access is designed to comprehensively address the portion of the procedure from the point of needle identification in the superficial subcutaneous tissue to vessel cannulation. This staged approach has several advantages: it creates two intraprocedural timeouts (following the initial needle entry of the skin and before vessel puncture), it incorporates the safe P-NT (avoiding inadvertent needle puncture of surrounding structures), and it provides an intraprocedural point of cessation in situations where the operator has difficulty identifying the needle tip. This method applies to Step 3 (ultrasound-guided venipuncture) of the safe insertion protocols for peripheral, central, femoral, and arterial cannulation.^{15,16,20,21,35,36}

In hospitals throughout the United States, POCUS is used by various clinicians, from experts such as radiologists, surgeons, and vascular access specialists to novices such as residents and registered nurses, with varying outcomes.^32–34 Intravenous and intraarterial cannulation is an invasive and often painful procedure currently lacking formal training and skills requirements. First-attempt success and iatrogenic complications with vascular access device placement are solely dependent on the operator’s ability to follow the needle tip from skin puncture to vessel penetration. Optimal training is recommended through formal programs involving simulation and proctored bedside training.

The Mastery Learning approach is an instructional strategy where students must achieve and demonstrate a level of mastery for knowledge and skill with a procedure.²⁶ A comprehensive ultrasound-guided educational approach is recommended for insertion training with peripheral and central veins, allowing the learner to achieve a predetermined level of competency.^11,37 Mastery Learning can be achieved systematically by breaking down complex skills into smaller, more manageable steps using clear objectives. Evidence indicates that students in mastery learning models outperform those in non-mastery models.^28,29 According to Winget and Persky,²⁹ this improved performance may stem from factors like enhanced motivation, frequent testing, and timely feedback, all integral to mastery learning’s structured approach. Applying this approach to vascular access, learning can be broken down into three key components: pertinent anatomy, ultrasound scanning with interpretation, and ultrasound-guided needle movement.

Clinicians must first begin with an educational foundation encompassing phlebology and arteriology. This education is designed to incorporate venous and arterial pathways, as well as the critical surrounding structures in all applicable access regions of the body. This knowledge and understanding assist the operator in determining the safest recommended approach for vascular access for the wide range of patient presentations from stable to emergent.

The second key component is the ultrasound. Familiarity with the operation of the machine itself can range from the key features of gain and depth to the use of color doppler. The operator will then develop a feel for the probe, as well as the weight and ease of movement when scanning. Mastering the ultrasound assessment protocols of the RaPeVA, RaCeVA, RaFeVa, and SIA allows for a safe, non-invasive method to identify structures and apply the ultrasonic acoustic windows of the short, long, and oblique axis in both the thoracic and femoral approaches.

Finally, the third key component combines anatomy and visualization with ultrasound-guided needle movement with the P-NT. To ensure safe needle advancement, the needle is first identified within the tissue, often described as a star sign. Using micro-movements, the probe is advanced forward until this star sign fades but is still visible. The needle is then advanced forward until the bright star sign is re-identified. This P-NT movement is repeated until successful venous or arterial cannulation is achieved. The development of kinesthetic muscle memory for the ultrasound probe and access needle has been demonstrated through the repeated use of simulation models with varying vein size structures without posing serious risks for patients and ultimately successfully transferring this drill into practice.³⁵

Applying the P-NT to the 3-Stations of the Needle allows for three critical intraprocedural time outs, confirming needle identification within the subcutaneous tissue, the outside wall of the vessel, and finally, cannulation (Table 2). According to procedural literature, a minimum of 50 cannulations are required to reach the level of success where the operator has confidence and a clear understanding of simple and complex presentations, safety and limitations, and the ability to troubleshoot. For novice operators, P-NT is best learned and mastered in the upper extremities due to the relatively low risk of iatrogenic complications. For experienced operators performing central access, the P-NT is safely performed using a micro-puncture needle. If the needle tip cannot be visualized, the procedure can be stopped before causing the patient harm.

Table 2.

Identifiable structures in Station 2.

Structures	Venous	Arterial	Nerve	Muscle	Pleura/Ligament/Lymph
Peripheral
Forearm	Cephalic	Radial, ulnar	Radial, ulnar, median	Brachioradialis	None
Antecubital region	Antecubital, brachial	Brachial	Median	Bicep, Pronator teres, supinator	None
Upper arm	Brachial, basilic, cephalic, axillary	Brachial, axillary	Brachial, ulnar, axillary	Bicep	Lymph
Thoracic
Infraclavicular	Axillary	Axillary	Axillary	Deltoid, pectoral major	Lung
Supraclavicular	External jugular, subclavian, brachiocephalic, jugular	Subclavian, brachiocephalic, carotid	Phrenic, vagal	Sternocleido-mastoid	Lung
Lower extremity
Lower leg	Saphenous, popliteal	Pedal, posterior/anterior tibial, popliteal	Saphenous, tibial	Gastrocnemius	None
Thigh	Superficial femoral, greater saphenous	Superficial femoral	Femoral, saphenous	Quadricep	None
Inguinal region	Common femoral	Common femoral	Femoral	Sartorius, adductor longus	Inguinal ligament

For upper extremity peripheral venous access, the P-NT ensures a straight trajectory to the vessel, assesses catheter-to-vein purchase, and avoids inadvertent nerve and arterial cannulation. In the thoracic region (the area located between the neck and abdomen), the P-NT avoids the critical structures of the pleural lining and arterial structures when accessing the axillary and supraclavicular approach to the subclavian and brachiocephalic veins. In the cervical and femoral approaches, the P-NT avoids inadvertent arterial cannulation. Finally, the critical advantage of the P-NT with arterial cannulation is ensuring the ideal trajectory angle of the catheter, first attempt success, and prevention of the inadvertent puncture of the back wall of the vessel to avoid the antiquated through and through technique.³⁶ Needle tip confirmation at these three critical stages builds confidence in the ability of the operator to avoid the mechanical complications of arterial, nerve, or pleural puncture through careful needle guidance when performing live proctored clinical cases.

Incorporating the 3 Stations of the Needle and the P-NT into a modular systems approach aligns with the Mastery Learning minimum performance scoring or global ratings to verify competency achievement.^28,38 This staged approach intends to reduce repeat punctures and prevent the escalation of device placement due to an operator’s unsuccessful attempt for peripheral, central, and arterial access.³⁹ Systematic approaches to training with assessment-based blended mastery learning utilize online education coupled with skills modules to reinforce and measure performance.^28,40–43 Blended education effectively combines e-learning courses, simulation skills modules, and supervised insertions to build, assess and measure proficiency and competency.

Conclusion

The ability to locate and effectively guide the needle tip is a skill required to achieve optimal success with ultrasound-guided needle insertions. Integrating a systematic approach to learning allows the acquisition of skills, including the 3 Stations of the Needle. Mastery learning processes aid in establishing proficiency and documenting competency for ultrasound insertions.

Footnotes

Acknowledgements

The authors would also like to recognize Aisha Cobbs for her editorial assistance.

Author contributions

M. O. and N. M. contributed to the conceptualization, writing, and review of the manuscript. All authors read and approved the final manuscript.

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.

Ethics statement

There are no human subjects in this article and informed consent is not applicable.

ORCID iDs

Matthew Ostroff

Nancy Moureau

References

Lamperti

Bodenham

Pittiruti

, et al. International evidence-based recommendations on ultrasound-guided vascular access. Intensive Care Med 2012; 38(7): 1105–1117.

Pittiruti

Hamilton

Biffi

, et al. ESPEN guidelines on parenteral nutrition: central venous catheters (access, care, diagnosis and therapy of complications). Clin Nutr 2009; 28(4): 365–377.

Bouaziz

Zetlaoui

Pierre

, et al. Guidelines on the use of ultrasound guidance for vascular access. Anaesth Crit Care Pain Med 2015; 34(1): 65–69.

Bodenham Chair

Babu

Bennett

, et al. Association of Anaesthetists of Great Britain and Ireland: safe vascular access 2016. Anaesthesia 2016; 71(5): 573–585.

Gorski

Hadaway

Hagle

, et al. Infusion therapy standards of practice, 8th edition. J Infus Nurs 2021; 44(1S Suppl. 1): S1–S224.

Franco-Sadud

Schnobrich

Mathews

, et al. Recommendations on the use of ultrasound guidance for central and peripheral vascular access in adults: a position statement of the Society of Hospital Medicine. J Hosp Med 2019; 14(9): E1–E22.

Bardin-Spencer

Spencer

TR.

Arterial insertion method: a new method for systematic evaluation of ultrasound-guided radial arterial catheterization. J Vasc Access 2021; 22(5): 733–738.

Lamperti

Biasucci

Disma

, et al. European Society of Anaesthesiology guidelines on peri-operative use of ultrasound-guided for vascular access (PERSEUS vascular access). Eur J Anaesthesiol 2020; 37(5): 344–376.

Helm

Klausner

Klemperer

, et al. Accepted but unacceptable: peripheral IV catheter failure. J Infus Nurs 2015; 38(3): 189–203.

10.

Pandurangadu

Tucker

Brackney

, et al. Ultrasound-guided intravenous catheter survival impacted by amount of catheter residing in the vein. Emerg Med J 2018; 35(9): 550–555.

11.

Nickel

Gorski

Kleidon

, et al. Infusion therapy standards of practice, 9th edition. J Infus Nurs 2024;47(1S Suppl. 1): S1–S285.

12.

Thompson

Steinheiser

Hotchkiss

, et al. Standards of care for peripheral intravenous catheters: evidence-based expert consensus. Br J Nurs 2024; 33(21): S32–S46.

13.

Pinelli

Pittiruti

Van Boxtel

, et al. GAVeCeLT-WoCoVA consensus on subcutaneously anchored securement devices for the securement of venous catheters: current evidence and recommendations for future research. J Vasc Access 2021; 22(5): 716–725.

14.

Singh

Tissot

Fraga

, et al. International evidence-based guidelines on Point of Care Ultrasound (POCUS) for critically ill neonates and children issued by the POCUS Working Group of the European Society of Paediatric and Neonatal Intensive Care (ESPNIC). Crit Care 2020; 24(1): 65.

15.

Spencer

Imbriaco

Bardin-Spencer

, et al. Safe Insertion of Arterial Catheters (SIA): an ultrasound-guided protocol to minimize complications for arterial cannulation. J Vasc Access 2024; 25(5): 1403–1408.

16.

Brescia

Pittiruti

Spencer

, et al. The SIP protocol update: eight strategies, incorporating Rapid Peripheral Vein Assessment (RaPeVA), to minimize complications associated with peripherally inserted central catheter insertion. J Vasc Access 2024; 25(1): 5–13.

17.

Spencer

Pittiruti

Rapid Central Vein Assessment (RaCeVA): a systematic, standardized approach for ultrasound assessment before central venous catheterization. J Vasc Access 2019; 20(3): 239–249.

18.

Brescia

Pittiruti

Ostroff

, et al. Rapid Femoral Vein Assessment (RaFeVA): a systematic protocol for ultrasound evaluation of the veins of the lower limb, so to optimize the insertion of femorally inserted central catheters. J Vasc Access 2021; 22(6): 863–872.

19.

Emoli

Cappuccio

Marche

, et al. Il protocollo ‘ISP’ (Inserzione Sicura dei PICC): un “bundle” di otto raccomandazioni per minimizzare le complicanze legate all’impianto <BR>dei cateteri centrali ad inserimento periferico (PICC). Assist Inferm Ric 2014; 33(2): 82–89.

20.

Brescia

Pittiruti

Ostroff

, et al. The SIF protocol: a seven-step strategy to minimize complications potentially related to the insertion of femorally inserted central catheters. J Vasc Access 2023; 24(4): 527–534.

21.

Brescia

Pittiruti

Ostroff

, et al. The SIC protocol: a seven-step strategy to minimize complications potentially related to the insertion of centrally inserted central catheters. J Vasc Access 2023; 24(2): 185–190.

22.

Piton

Capellier

Winiszewski

Ultrasound-guided vessel puncture: calling for Pythagoras’ help. Crit Care 2018; 22(1): 292.

23.

Beard

Edwards

ESRA19-0329 use of Pythagorean theorem to optimise needle length selection for in-plane ultrasound guided approaches to regional anaesthesia. Reg Anesth Pain Med 2019; 44: A201–A202.

24.

De Cassai

Sandei

Carron

. Trigonometry in daily ultrasound practice. Crit Care 2018; 22(1): 356.

25.

Smit

Raadsen

Blans

, et al. Bedside ultrasound to detect central venous catheter misplacement and associated iatrogenic complications: a systematic review and meta-analysis. Crit Care 2018; 22(1): 65.

26.

Bloom

BS.

Learning for mastery. Instruction and curriculum. Regional Education Laboratory for the Carolinas and Virginia, topical papers and reprints, Number 1. Durham, NC: Regional Education Laboratory for the Carolinas and Virginia, https://eric.ed.gov/?id=ED053419 (1968, accessed 27 January 2025)

27.

Moureau

Johnson

Mastery learning certificate bundle for ultrasound-guided peripheral intravenous catheter insertion, https://www.piccexcellence.com/ugpiv-mastery/ (17 November 2023, accessed 27 January 2025)

28.

Amick

Feinsmith

Davis

, et al. Simulation-based mastery learning improves ultrasound-guided peripheral intravenous catheter insertion skills of practicing nurses. Simul Healthc 2022; 17(1): 7–14.

29.

Winget

Persky

AM.

A practical review of mastery learning. Am J Pharm Educ 2022; 86(10): ajpe8906.

30.

Sahlani

Thompson

Vira

, et al. Bedside ultrasound procedures: musculoskeletal and non-musculoskeletal. Eur J Trauma Emerg Surg 2016; 42(2): 127–138.

31.

Elia

Ferrari

Molino

, et al. Standard-length catheters vs long catheters in ultrasound-guided peripheral vein cannulation. Am J Emerg Med 2012; 30(5): 712–716.

32.

Smith

Should nurses be trained to use ultrasound for intravenous access to patients with difficult veins?

Emerg Nurse 2018; 26(2): 18–24.

33.

Pittiruti

Annetta

D’andrea

Point-of-care ultrasound for vascular access in neonates and children. Eur J Pediatr 2023; 183(3): 1073–1078.

34.

Adams

Saleem

Patel

, et al. Point of care ultrasound utilization for vascular access in trauma patients. Curr Anesthesiol Rep 2024; 14(4): 576–583.

35.

Lee

Kwon

, et al. Simulation-based training using a vessel phantom effectively improved first attempt success and dynamic needle-tip positioning ability for ultrasound-guided radial artery cannulation in real patients: an assessor-blinded randomized controlled study. PLoS One 2020; 15(6): e0234567.

36.

Imbriaco

Spencer

Bardin-Spencer

10 best practice tips with radial arterial catheterization. J Vasc Access 2024; 25(2): 363–368.

37.

Benner

From novice to expert. Am J Nurs 1982; 82(3): 402–407.

38.

Loon

FHV

Scholten

Korsten

, et al. The learning curve for ultrasound-guided peripheral intravenous cannulation in adults: a multicenter study. Med Ultrason 2022; 24(2): 188.

39.

Galen

Baron

Young

, et al. Reducing peripherally inserted central catheters and midline catheters by training nurses in ultrasound-guided peripheral intravenous catheter placement. BMJ Qual Saf 2020; 29(3): 245–249.

40.

Jørgensen

Laursen

Konge

, et al. Education in the placement of ultrasound-guided peripheral venous catheters: a systematic review. Scand J Trauma Resusc Emerg Med 2021; 29(1): 83.

41.

Akpan

Mastery learning—Benjamin Bloom. In: Akpan

Kennedy

(eds) Science education in theory and practice. Cham: Springer, 2020, pp.149–162.

42.

McGaghie

Issenberg

Cohen

, et al. Does simulation-based medical education with deliberate practice yield better results than traditional clinical education? A meta-analytic comparative review of the evidence. Acad Med 2011; 86(6): 706–711.

43.

Barsuk

Cohen

Potts

, et al. Dissemination of a simulation-based mastery learning intervention reduces central line-associated bloodstream infections. BMJ Qual Saf 2014; 23(9): 749–756.