Intraosseous Vascular Access

Anatomy and Physiology

Potential IO access sites include the sternum, clavicle, humeral head, iliac crest, distal femur, proximal tibia, distal tibia, and calcaneus. In adults, the preferred sites are the proximal tibia, humeral head, and sternum, while in infants and neonates, the distal femur, proximal tibia, and distal tibia are commonly used. Palpation of both bony margins is recommended to ensure correct needle placement; this allows insertion perpendicular to the bone surface and aligned with the appropriate axis. As a general guide for site measurement, 1 cm may be approximated as 1 fingerbreadth of the clinician.

Recommended IO insertion landmarks by site include:

• Sternum
  • One cm below the sternal notch
• Humerus
  • Two cm above the surgical neck, into the greater tubercle at approximately 45° to the anterior plane
    • The arm should be internally rotated with the patient’s hand resting on the abdomen and the elbow flexed to 90° to avoid injuring the biceps tendon.
• Distal femur
  • 1 cm proximal to the patella and 1 to 2 cm medially, with the leg straightened and aligned in the anterior plane
• Proximal tibia
  • 1 to 2 cm inferior and medial to the tibial tuberosity on the flat anterior surface
• Distal tibia
  • 2 cm proximal to the medial malleolus on the flat surface of the bone

Indications

The following are indications for IO placement:

• Unable to obtain IV access 
• The need for rapid venous access and standard IV access cannot be quickly secured
• Blood for laboratory analysis or point-of-care testing
• Access for contrast injection for radiologic evaluation [14]

Contraindications

The following are contraindications to IO placement:

• Adequate venous access has already been established
• Fracture at the insertion site
• Burn at the insertion site
• Cellulitis or infection overlying the insertion site
• Osteogenesis imperfect
• Osteoporosis (relative)
• Previous IO attempted site, especially if within the past 48 hours
• Recent orthopedic surgery at the insertion site [15]

Equipment

IO access equipment has evolved significantly, providing clinicians with multiple device options tailored to patient age, clinical scenario, and clinician preference. Most IO systems consist of a needle set, driver (manual or powered), and stabilization accessories.

There are 3 main categories of IO devices:

• Manual devices
  • These traditional devices include a hand-twisted IO needle with a trocar-style tip. They require physical force and precision for insertion. They are inexpensive and reliable but require more skill and time, especially in emergencies.
  • These devices include the Jamshidi needle and the Diekman-modified needle.
  • Sternal-specific manual devices, such as the First Access for Shock and Trauma (FAST1) Intraosseous Infusion System, are designed to avoid posterior cortex penetration into the thoracic aorta. The FAST1 is the preferred choice for sternal IO access.[15]
• Powered devices
  • Battery-operated IO drills have become the most commonly used devices in emergencies. These drills rapidly insert a needle into the medullary space with minimal effort, improving speed and success rates, especially in high-stress environments. 
  • One example is the EZ-IO system, which comes with size-specific color-coded needles (commonly 15 mm for pediatrics and 25–45 mm for adults) and safety stops to prevent over-penetration.
  • A comparative study of IO devices found battery-powered systems more user-friendly and accurate than manual systems, with the EZ-IO receiving the highest ratings.[16]
• Spring-loaded devices
  • These include the Bone Injection Gun (BIG), which uses a spring-loaded mechanism to drive the needle into the bone. This device is designed for rapid, one-handed use and is available in adult and pediatric sizes.

Additional equipment commonly used with IO insertion includes:

• Chlorhexidine or povidone-iodine swabs for site antisepsis
• Syringes for aspiration and flushing (to confirm placement and maintain patency)
• Luer-lock IV extension sets or pressure bags (since IO flow rates may require pressure to overcome resistance)
• Securing devices or dressings to stabilize the needle and prevent dislodgement
• Infusion pump or manual pressure bag for continuous medication or fluid administration

Preparation

A standard sterile technique should always be maintained during IO insertion to reduce the risk of infection. The selected anatomic site is identified by palpating bony landmarks and may be marked for accuracy before insertion. Once the site is confirmed, local anesthetic (eg, lidocaine 1%) can be injected into the overlying soft tissues and periosteum to minimize discomfort, particularly in conscious patients. The procedure is generally well-tolerated with local anesthesia in a patient who is awake.[15]

Technique or Treatment

General Technique for IO Access

Aseptic technique is essential throughout the IO procedure to minimize the risk of infection. Select the appropriate anatomical site based on patient age, body habitus, and clinical setting. Palpation of bony landmarks is critical to ensure accurate needle placement. Marking the site is recommended for additional precision. In awake individuals, local anesthesia—typically lidocaine 1%—should be infiltrated into the skin and periosteum to reduce pain during insertion. Allow adequate time for the anesthetic to take effect before proceeding.

The IO needle should be inserted perpendicularly to the bone, taking special care in pediatric patients to avoid the epiphyseal growth plate. Once the needle contacts the bone, a distinct hard stop is felt. At least 5 mm of the needle shaft should remain visible above the skin at the hard stop, indicating that the catheter is long enough to penetrate the medullary space. Select a longer needle or a site with less overlying soft tissue if the needle is too short. In obese individuals, the proximal tibia is preferred due to relatively decreased subcutaneous tissue.

Confirm IO placement by checking for needle stability, attempting bone marrow aspiration, and ensuring free flow of saline flush without evidence of subcutaneous infiltration. Failure to aspirate marrow does not necessarily indicate poor placement; a saline flush followed by a second aspiration attempt may be effective. Once placement is confirmed, flush the IO line with 5 to 10 mL of normal saline in adults or 2 to 5 mL in infants and children. Despite proper technique, some patients may experience significant pain during flushing. In such cases, 2% lidocaine (20–40 mg in adults or 0.5 mg/kg in pediatric patients) may be injected through the IO line for analgesia. Allow approximately 2 minutes for the lidocaine to take effect before infusing fluids. Though results are mixed, some evidence supports lidocaine use for infusion-related pain.[17][18]

Stabilization techniques vary by device and are often included in preassembled kits provided by manufacturers. Properly securing the IO line is essential to prevent dislodgement or bending of the needle. After the procedure, document the date and time of placement. IO access should be considered a temporary measure and should not exceed 24 hours due to the increased risk of complications. Once alternative vascular access is established, the IO device should be removed, and the site should be dressed appropriately.

Device-Specific IO Insertion Technique

EZ-IO (battery-powered)

• Most commonly used and rated highest for ease and accuracy
• Inserted at a 90-degree angle with firm, steady pressure using the drill
• Confirm placement (eg, aspirating marrow or observing flush flow)
• Preferred for use at the proximal tibia, humeral head, or distal tibia

Bone Injection Gun (BIG)

• Spring-loaded, single-use, semi-automatic device
• Commonly used in emergency and field settings
• Placed with 1 motion at the appropriate site (eg, tibia)
• Simpler than manual devices, though training is required for optimal use

Manual Devices

• Jamshidi, Diekman-modified needle
  • Require significant manual force and precise technique
  • Inserted with firm downward rotation to bore through the cortex
  • More commonly used when powered devices are unavailable
  • Suitable for various sites but associated with more insertion difficulty and fatigue
    • Clinicians should always consult device-specific instructions to ensure correct technique and minimize complications.
• FAST1 (sternal IO system)
  • Designed specifically for the sternum
  • Placed 1 cm below the sternal notch
  • Multiple stabilizer needles anchor the device (to avoid posterior cortex penetration and reduce the risk to thoracic structures)
  • Ideal in adult patients (when upper extremity access is not feasible)

Complications

While IO access is a valuable and often life-saving technique, it is not without potential complications. One of the most common complications is fluid extravasation, which can occur when the IO needle penetrates the posterior cortex, is inadvertently placed in a fracture site, or is inserted into a bone previously used for IO access. Extravasation of fluids, particularly caustic substances, can lead to serious outcomes such as compartment syndrome, soft tissue necrosis, or other local tissue injuries. In these situations, early detection and discontinuation of infusion are critical. Fractures are another complication, particularly in patients with underlying bone disease or when excessive force or incorrect technique is used during needle insertion; pediatric and osteoporotic individuals are especially at risk.

Infectious complications such as cellulitis and osteomyelitis can develop, particularly if the aseptic technique is not followed or the IO line remains below the recommended 24-hour limit.[19] Though rare, fat embolism has been reported, usually resulting from aggressive access of the medullary cavity and excessive pressure during infusion.[20] Mechanical issues also occur. A bent IO needle may resist normal extraction and, in some cases, require surgical removal. When infusion through a newly placed IO line fails, it is often due to incomplete penetration of the needle into the medullary space. Advancing the needle slightly further typically resolves the issue. A significant concern in pediatric individuals is accidental insertion into the epiphyseal plate, which can result in growth plate necrosis and long-term growth impairment. To avoid this, clinicians must be meticulous with landmark identification and insertion technique specific to the patient’s age and developmental stage.

Clinical Significance

First introduced in 1922, IO access remains an underutilized yet highly effective alternative to IV access, particularly in emergency settings where IV access is delayed or unsuccessful.[15] Despite its demonstrated reliability, speed of placement, and applicability across a wide range of patient populations, comfort with and confidence in IO use remain low among many clinicians in prehospital and hospital settings. This hesitance persists even though IO access often proves superior to IV access in critically ill individuals, including those in cardiac arrest.[20]

Targeted education and procedural training are essential to improving adoption. Study results have shown that protocol adjustments and skill-building initiatives significantly increase the use and effectiveness of IO access, especially among prehospital clinicians and in cardiac arrest scenarios.[21][22] Moreover, clinician stress levels and confidence have been shown to directly impact performance, with less-stressed and more confident clinicians performing better under pressure.[23] Increasing familiarity and reducing anxiety through simulation-based training and team-based drills can enhance individual and team outcomes. Clinicians must also understand that IO access should not be delayed in favor of repeated IV attempts in emergent situations. Time-sensitive interventions, such as epinephrine administration in cardiac arrest, can be significantly delayed by multiple failed IV attempts, potentially worsening patient outcomes.[24]

In addition to fluid and medication delivery, IO access is valuable for obtaining diagnostic blood samples. Strong correlations with IV samples have been demonstrated for key parameters, including blood gases, hematocrit, bicarbonate, creatinine, sodium, and creatine kinase.[1][2] While glucose values show inconsistent correlation and potassium is generally elevated in IO samples, blood typing remains accurate, even after IO transfusion, enabling emergent typing and crossmatching.[22][25] White blood cell and platelet counts, however, are unreliable. Though further studies are warranted to validate point-of-care testing via IO access, current evidence supports its utility in critical scenarios. Once IV access is secured, laboratory values should be repeated to confirm accuracy.[2] Clinicians do not need to discard the first aspirate when obtaining labs from an IO line.[26]  Ultimately, IO access represents a life-saving procedure that should be embraced through interprofessional training and protocol optimization to maximize its benefit in time-critical emergencies.

Enhancing Healthcare Team Outcomes

Effective IO vascular access implementation demands well-coordinated interprofessional collaboration among clinicians, including physicians, advanced practitioners, nurses, pharmacists, paramedics, and support staff. Each team member is vital in ensuring safe, efficient access during time-critical emergencies. Physicians and advanced practitioners must assess clinical indications and guide site selection while maintaining situational awareness. Nurses and paramedics often lead insertion efforts in prehospital or critical care settings and must be trained to quickly identify candidates for IO access and perform the procedure precisely. Pharmacists contribute by confirming drug compatibility, dosing, and dilution for IO administration—critical for medications such as epinephrine, vasopressors, or sedatives. Timely communication, shared mental models, and clear role delegation during resuscitation are essential to avoid delays and minimize errors.

To optimize patient-centered care and safety, structured training programs and protocol-driven strategies should be adopted across disciplines. Simulation-based training can help standardize workflows, reduce procedural anxiety, and improve insertion success rates, especially in high-acuity scenarios like cardiac arrest or trauma. Multidisciplinary debriefs after critical events can identify system gaps, reinforce best practices, and support continuous improvement in team performance. Effective care coordination—including prompt documentation, appropriate site monitoring, and timely transition to definitive access—reduces complications and supports better outcomes. Ultimately, IO access is most successful and beneficial when supported by seamless teamwork, shared accountability, and a commitment to high-reliability care.