Intraosseous infusion

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Intraosseous infusion
811 Tibia and fibula.jpg
The tibia IO insertion site is just below the medial condyle, labeled in this picture.
MeSH D017148
eMedicine 80431

Intraosseous infusion (IO) is the process of injecting medication, fluids, or blood products directly into the bone marrow; [1] this provides a non-collapsible entry point into the systemic venous system. [2] The intraosseous infusion technique is used to provide fluids and medication when intravenous access is not available or not feasible. Intraosseous infusions allow for the administered medications and fluids to go directly into the vascular system. [3] The IO route of fluid and medication administration is an alternative to the preferred intravascular route when the latter cannot be established promptly in emergent situations. Intraosseous infusions are used when people have compromised intravenous access and need immediate delivery of life-saving fluids and medications. [3]

Contents

Background

The use of the IV route to administer fluids has been around since the 1830s, and, in 1922, Cecil K. Drinker et al. saw that bone, specifically the sternum, could also be used as a route of administration for emergency purposes. [4] To continue the expansion of knowledge regarding IO administration, a successful blood transfusion took place in 1940 using the sternum, and afterward, in 1941, Tocantins and O'Neill demonstrated successful vascular access using the bone marrow cavity of a long bone in rabbits. [4] Because of Tocantins and O'Neill's success in their experiments with rabbits, human clinical trials were established using mainly the body of the sternum or the manubrium for access. [5] Emanuel Papper and others then continued to advocate, research, and make advances on behalf of the IO administration. [6] Once Papper showed that the bone marrow space could be used with comparable success to administer IV fluids and drugs, intraosseous infusion was popularized during World War II to prevent soldiers' deaths via hemorrhagic shock. [7] While popular in the field during WWII, the use of IO was not seen as a standard for emergencies until the 1980s, and only so for children. [7] With the rise of technology allowing the ease of technique of IO, and a lower risk of complications like bloodstream infections than when using peripheral access, the alternative of IO access has increased throughout the years for adults, as well. [7] IO is now recommended in Advanced Cardiac and Pediatric Advanced Life Support treatment protocols, in cases where access via IV cannot be established on time. [4]

Indications

Intraosseous access is indicated in emergency situations, such as when a person experiences some type of major trauma like shock, cardiac arrest, severe dehydration, [8] or severe gastrointestinal hemorrhage. [9] IO access can provide the quickest way to rapidly infuse needed medications and fluids in an emergency situation. [8] In people who experience critical trauma and who do not have adequate blood pressure, the IO route doubles the success rate of the peripheral IV route.[ citation needed ]

In addition to the emergency clinical scenario that can call for an IO route to be used, IO access is only indicated when access to peripheral veins is either not possible or delayed. When IV access is either not possible or delayed, other indications for utilizing the IO route include administering contrast if needed for radiology scans and drawing blood for laboratory testing and analysis. [10] Situations that can result in decreased or delayed access to peripheral veins, and thus necessitate the use of an IO route to infuse medications and fluids include circumstances such as burns, fluid accumulation (edema), past IV drug use, obesity, and very low blood pressure. [8]

Contraindications

  1. Having adequate and timely peripheral venous access is a major contraindication to obtaining IO access.
  2. Fractures in the bone at the site of device insertion
  3. Burn damage to the tissues around the site of device insertion
  4. Cellulitis or other type of skin infection at the site of device insertion
  5. Osteogenesis imperfecta, also referred to as Brittle Bone Disease
  6. Osteoporosis [10]
  7. Osteomyelitis
  8. Osteopetrosis
  9. Osteopenia
  10. Recent orthopedic surgery
  11. A recent failed attempt at device insertion in the same bone [8]

Procedure

An IO infusion can be used on adult or pediatric populations when traditional methods of vascular access are difficult or otherwise cause unwanted delayed management of the administration of medications. The IO site can be used for 24 hours and should be removed as soon as intravenous access has been gained. Prolonged use of an IO site, lasting longer than 24 hours, is associated with osteomyelitis (an infection in the bone). [3]

Intraosseous infusion-- needle insertion into anterior tibia

The needle is inserted through the bone's hard cortex and into the soft marrow interior, which allows immediate access to the vascular system. The IO needle is positioned at a 90 degree angle to the injection site, and is advanced through manual traction, impact driven force, or power driven. Each IO device has different designated insertion locations. The most common site of insertion is the antero-medial aspect of the upper, proximal tibia as this site lies just under the skin and is easily located. Other insertion sites include the anterior aspect of the femur, the superior iliac crest, proximal humerus, proximal tibia, distal tibia and the sternum (manubrium). [1] Although intravascular access is still the preferred method for medication delivery in the prehospital area, IO access for adults has become more common. As of 2010, the American Heart Association no longer recommends using the endotracheal tube (ET) for resuscitation drugs, except as a last resort when IV or IO access cannot be gained. [1] ET absorption of medications is poor, and optimal ET drug dosings are unknown. IO administration is becoming more common in civilian and military pre-hospital emergency medical services (EMS) systems globally. [11]

Intraosseous access has roughly the same absorption rate as IV access, and allows for fluid resuscitation. For example, sodium bicarbonate can be administered IO during a cardiac arrest when IV access is unavailable. [1] High flow rates are attainable with an IO infusion, up to 125 milliliters per minute. This high rate of flow is achieved using a pressure bag to administer the infusion directly into the bone. Large volume IO infusions are known to be painful. 1% lidocaine is used to ease the pain associated with large volume IO infusions in conscious people. [3]

Complications

Like any medical procedure, intraosseous infusion has some potential complications. In a review by Tyler et al., an analysis across the included studies found the overall complication rate associated with IO infusions to be less than 1% (0.9%). [12]

Complications include:

Many of these potential complications can be prevented with simple measures like using good technique and keeping the period of IO infusion short by switching to IV as soon as it becomes feasible. [14] Bone fracture complications can be decreased by using modern techniques and requiring more regular training in the methods of intraosseous marrow access for infusion. Extravasation can lead to the more serious complication of compartment syndrome. The risk of developing compartment syndrome can be reduced by medical personnel checking the infusion site regularly for any signs of swelling. Swelling could indicate misplacement of the catheter. Avoiding puncturing the same bone in 48 hours can also lessen the risk of developing this complication. The risk of osteomyelitis, while very low ( <1%), can be further lessened by using sterile, hygienic practices and modern devices to make the puncture. Damage to the epiphyseal plate can be avoided by training medical personnel about proper landmarks to be used for determining puncture sites. [13]

Devices

Axial CT with left humeral head EZ-IO (power driver device) infusion of contrast. Intraosseous Infusion.PNG
Axial CT with left humeral head EZ-IO (power driver device) infusion of contrast.

Intraosseous devices allow quick and safe access to the vascular system for fluid and drug administration. After proper education and training, medical professionals can obtain vascular access via the IO route of administration by using one of the multiple devices that have been approved by the FDA for 24-hour use. [7] There are several FDA approved IO devices, categorized by their mechanism of action:

BIG IO devices (spring-loaded) Io-device.jpg
BIG IO devices (spring-loaded)
  1. Power Driver: EZ-IO By Arrow Teleflex.
    • The EZ-IO device is a small device that works like a traditional drill and drill bit, consisting of a reusable, battery-powered driver and disposable, hollow IO needle. [15] A trigger allows for the IO needle to enter the bone marrow space at a preset length without any pressure being applied. [16] In the United States, the FDA has approved the use of the EZ-IO device in the proximal tibia and the head of the humerus. [16]
  2. Spring-Loaded: the Bone Injection Gun (BIG) and the Pyng Medical Corporation FAST 1
    • The First Access for Shock and Trauma (FAST 1) spring-loaded device is designed for use in the sternum of an adult. The FAST 1 device consists of multiple needles in a probe that penetrates the manubrium once manual pressure is applied. [16]
    • The Bone Injection Gun (BIG) device is a small, plastic, disposable, spring-loaded device that has a trigger that shoots the IO needle into the IO insertion site, which is more than likely in the proximal tibia. [16]
  3. Manual / Hand Powered: Hollow steel manually inserted needles have been around since the inception of IO administration, and use a removable trocar to aid in the insertion of the needle. Dense adult bone limits its use, but manual devices are commonly used in children because of their safety profile and ease of use, once training has taken place. [7] The three most widely used are: [16]
    • Cardinal Health Jamishidi/Illinois needle
    • Cook Critical Care threaded Sur-Fast needle
    • Cook Critical Care Dieckman modified needle

Each device is capable of achieving rapid vascular access, despite the mechanism of action, with insertion times comparable to the IV administration route. [16]

Special Populations

Pediatrics

Intraosseous infusion, pediatric Intraosseous infusion, pediatric.jpg
Intraosseous infusion, pediatric

A comparison of intravenous  (IV), intramuscular  (IM), and intraosseous (IO) routes of administration concluded that the intraosseous (IO) route is the preferred method versus intramuscular (IM) and comparable to intravenous (IV) administration in delivering pediatric anaesthetic drugs. [17]

Intraosseous infusion (IO) is used in pediatric populations during anesthesia when other intravenous access, central venous catherization or venous cutdown, are difficult to use or cannot be used. When individuals are severely ill and need "rapid, efficient, and safe delivery of drugs", IO is used.[ citation needed ] When inserting the intraosseous needle into a conscious individual, this can be very painful. For children, anesthesia is not recommended before this procedure for non-emergency situations. Instead, distracting and holding the child is preferred. Intraosseous infusion is used in instances such as, "immediate indication/life-threatening emergency, cardiac/respiratory arrest, acute shock, hypothermia, obesity, edema, thermal injury, etc."[ citation needed ]

For children, the preferred sites of IO are the distal tibia, proximal tibia, and distal femur. The distal end of the tibia is the preferred site because it is easy to access and the most reliable. Depending on the procedure, a variety of needles are used for IO. For example, "standard steel hypodermic, butterfly, spinal, trephine, sternal, and standard bone marrow needles are used." Needles that have a short shaft are preferred and safe. For infants up to 6 to 8 months old, 18-gauge needles are used and for children more than 8 months old, 15- or 16- gauge needles are used. [18] A study by Glaeser et al., concluded that individuals who received IO vs. peripheral and central intravenous access were able to obtain much faster and more successful IO access. Another study, by Fiorito et al., observed the safety of IO use during the transportation of critically ill pediatric individuals. Based on the results, they concluded that the use of IO was safe, based on 78% successful placement of the IO needle and complications that occurred in only 12% of the cases. [19]

Similarly to adults, contradictions for IO infusion use in pediatrics include bone diseases such as osteogenesis imperfecta and osteopetrosis, and fractures. Others include cellulitis, burns, and infections at the access site. [20]

Related Research Articles

<span class="mw-page-title-main">Central venous catheter</span> A tubular device placed in a large vein used to administer medicines

A central venous catheter (CVC), also known as a central line (c-line), central venous line, or central venous access catheter, is a catheter placed into a large vein. It is a form of venous access. Placement of larger catheters in more centrally located veins is often needed in critically ill patients, or in those requiring prolonged intravenous therapies, for more reliable vascular access. These catheters are commonly placed in veins in the neck, chest, groin, or through veins in the arms.

<span class="mw-page-title-main">Intravenous therapy</span> Medication administered into a vein

Intravenous therapy is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutrients for those who cannot, or will not—due to reduced mental states or otherwise—consume food or water by mouth. It may also be used to administer medications or other medical therapy such as blood products or electrolytes to correct electrolyte imbalances. Attempts at providing intravenous therapy have been recorded as early as the 1400s, but the practice did not become widespread until the 1900s after the development of techniques for safe, effective use.

<span class="mw-page-title-main">Route of administration</span> Path by which a drug, fluid, poison, or other substance is taken into the body

In pharmacology and toxicology, a route of administration is the way by which a drug, fluid, poison, or other substance is taken into the body.

<span class="mw-page-title-main">Subcutaneous administration</span> Insertion of medication under the skin

Subcutaneous administration is the insertion of medications beneath the skin either by injection or infusion.

<span class="mw-page-title-main">Battlefield medicine</span> Treatment of wounded combatants and non-combatants in or near an area of combat

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<span class="mw-page-title-main">Injection (medicine)</span> Method of medication administration

An injection is the act of administering a liquid, especially a drug, into a person's body using a needle and a syringe. An injection is considered a form of parenteral drug administration; it does not involve absorption in the digestive tract. This allows the medication to be absorbed more rapidly and avoid the first pass effect. There are many types of injection, which are generally named after the body tissue the injection is administered into. This includes common injections such as subcutaneous, intramuscular, and intravenous injections, as well as less common injections such as intraperitoneal, intraosseous, intracardiac, intraarticular, and intracavernous injections.

<span class="mw-page-title-main">Epidural administration</span> Medication injected into the epidural space of the spine

Epidural administration is a method of medication administration in which a medicine is injected into the epidural space around the spinal cord. The epidural route is used by physicians and nurse anesthetists to administer local anesthetic agents, analgesics, diagnostic medicines such as radiocontrast agents, and other medicines such as glucocorticoids. Epidural administration involves the placement of a catheter into the epidural space, which may remain in place for the duration of the treatment. The technique of intentional epidural administration of medication was first described in 1921 by Spanish military surgeon Fidel Pagés.

<span class="mw-page-title-main">Peripherally inserted central catheter</span> Catheter intended for long periods of use

A peripherally inserted central catheter, less commonly called a percutaneous indwelling central catheter, is a form of intravenous access that can be used for a prolonged period of time or for administration of substances that should not be done peripherally. It is a catheter that enters the body through the skin (percutaneously) at a peripheral site, extends to the superior vena cava, and stays in place for days, weeks or even months.

<span class="mw-page-title-main">Advanced life support</span> Life-saving protocols

Advanced Life Support (ALS) is a set of life saving protocols and skills that extend basic life support to further support the circulation and provide an open airway and adequate ventilation (breathing).

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<span class="mw-page-title-main">Peripheral venous catheter</span> Medical device for administering intravenous therapy

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References

  1. 1 2 3 4 Luck, Raemma P.; Haines, Christopher; Mull, Colette C. (2010). "Intraosseous access". The Journal of Emergency Medicine. 39 (4): 468–475. doi:10.1016/j.jemermed.2009.04.054. ISSN   0736-4679. PMID   19545966.
  2. Tobias JD, Ross AK (2010). "Intraosseous infusions: a review for the anesthesiologist with a focus on pediatric use". Anesthesia & Analgesia. 110 (2): 391–401. doi: 10.1213/ane.0b013e3181c03c7f . PMID   19897801. S2CID   22669421.
  3. 1 2 3 4 Day, Michael W. (2011). "Intraosseous Devices for Intravascular Access in Adult Trauma Patients". Critical Care Nurse. 31 (2): 76–89. doi: 10.4037/ccn2011615 . PMID   21459867 via EBSCO Host.
  4. 1 2 3 LaRocco, Brian G.; Wang, Henry E. (2003). "Intraosseous Infusion". Prehospital Emergency Care. 7 (2): 280–285. doi:10.1080/10903120390936950. ISSN   1090-3127. PMID   12710793. S2CID   72638403.
  5. Foex, B. A (2000). "Discovery of the intraosseous route for fluid administration". Emergency Medicine Journal. 17 (2): 136–137. doi:10.1136/emj.17.2.136. PMC   1725359 . PMID   10718241.
  6. Paxton, James H (2012). "Intraosseous vascular access: A review". Trauma. 14 (3): 195–232. doi:10.1177/1460408611430175. ISSN   1460-4086. S2CID   75480795.
  7. 1 2 3 4 5 The Consortium on Intraosseous Vascular Access in Healthcare Practice (2010). "Recommendations for the Use of Intraosseous Vascular Access for Emergent and Nonemergent Situations in Various Health Care Settings: A Consensus Paper". Critical Care Nurse. 30 (6): e1–e7. doi:10.4037/ccn2010632. ISSN   0279-5442. PMID   21123225. S2CID   9445111.
  8. 1 2 3 4 Petitpas, F.; Guenezan, J.; Vendeuvre, T.; Scepi, M.; Oriot, D.; Mimoz, O. (2016). "Use of intra-osseous access in adults: a systematic review". Critical Care. 20: 102. doi: 10.1186/s13054-016-1277-6 . ISSN   1466-609X. PMC   4831096 . PMID   27075364.
  9. D'Amore, Katrina; Swaminathan, Anand (2020). "Massive Gastrointestinal Hemorrhage". Emergency Medicine Clinics of North America. 38 (4): 871–889. doi:10.1016/j.emc.2020.06.008. ISSN   1558-0539. PMID   32981623. S2CID   222151867.
  10. 1 2 Dornhofer, Peter; Kellar, Jesse Z. (2021), "Intraosseous Vascular Access", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID   32119260 , retrieved 2021-07-27
  11. Paxton, James H.; Knuth, Thomas E.; Klausner, Howard A. (2009). "Proximal Humerus Intraosseous Infusion: A Preferred Emergency Venous Access". Journal of Trauma-Injury Infection & Critical Care. 67 (3): 606–611. doi:10.1097/ta.0b013e3181b16f42. PMID   19741408.
  12. 1 2 Tyler, Joseph Antony; Perkins, Zane; De'Ath, Henry Dudley (2021). "Intraosseous access in the resuscitation of trauma patients: a literature review". European Journal of Trauma and Emergency Surgery. 47 (1): 47–55. doi:10.1007/s00068-020-01327-y. ISSN   1863-9941. PMID   32078703. S2CID   211217544.
  13. 1 2 Neuhaus, Diego (2014). "Intraosseous infusion in elective and emergency pediatric anesthesia: when should we use it?". Current Opinion in Anesthesiology. 27 (3): 282–287. doi:10.1097/ACO.0000000000000069. ISSN   1473-6500. PMID   24651308. S2CID   32076647.
  14. Katz, D. S.; Wojtowycz, A. R. (1994). "Tibial fracture: a complication of intraosseous infusion". The American Journal of Emergency Medicine. 12 (2): 258–259. doi:10.1016/0735-6757(94)90261-5. ISSN   0735-6757. PMID   8161406.
  15. Weiser, Giora; Hoffmann, Yoav; Galbraith, Roger; Shavit, Itai (2012). "Current advances in intraosseous infusion – A systematic review". Resuscitation. 83 (1): 20–26. doi:10.1016/j.resuscitation.2011.07.020. ISSN   0300-9572. PMID   21871243.
  16. 1 2 3 4 5 6 Blumberg, Stephen M.; Gorn, Michael; Crain, Ellen F. (2008). "Intraosseous Infusion: A Review of Methods and Novel Devices". Pediatric Emergency Care. 24 (1): 50–56. doi:10.1097/pec.0b013e31815f727b. ISSN   0749-5161. PMID   18212613. S2CID   36188009.
  17. Moore GP, Pace SA, Busby W (1989). "Comparison of intraosseous, intramuscular, and intravenous administration of succinylcholine". Pediatric Emergency Care. 5 (4): 209–210. doi:10.1097/00006565-198912000-00001. PMID   2602189. S2CID   24125346.
  18. Peck, Karen Rowe; Altieri, Michael (1989). "Intraosseous Infusions". Orthopaedic Nursing. 8 (3): 46–48. doi:10.1097/00006416-198905000-00013. ISSN   0744-6020.
  19. Buck, Marcia L; Wiggins, Barbara S; Sesler, Jefferson M (2007). "Intraosseous Drug Administration in Children and Adults During Cardiopulmonary Resuscitation". Annals of Pharmacotherapy. 41 (10): 1679–1686. doi:10.1345/aph.1K168. ISSN   1060-0280. PMID   17698894. S2CID   20835675.
  20. Engle, William A. (2006). "Intraosseous Access for Administration of Medications in Neonates". Clinics in Perinatology. 33 (1): 161–168. doi:10.1016/j.clp.2005.11.006. PMID   16533642.