Intraosseous (IO) access is a medical procedure that involves inserting a specialized needle directly into the bone marrow cavity. This method provides a non-collapsible entry point into the systemic venous system, allowing for the rapid delivery of fluids, medications, or blood products. It serves as a swift and reliable alternative when traditional intravenous (IV) access is difficult to obtain or would cause significant delays in life-saving treatment. It is a significant tool in emergency situations requiring immediate vascular access.
When Intraosseous Access is Used
Intraosseous access is a necessary intervention in critical medical emergencies where immediate vascular access is paramount. This technique is employed when conventional intravenous access is challenging or impossible to establish quickly. Such scenarios include cardiac arrest, severe shock, and massive trauma, where every second counts in delivering life-saving interventions.
Delays in administering fluids or medications can significantly worsen patient outcomes. Conditions like severe bleeding, systemic infections leading to shock, or respiratory failure also necessitate immediate and reliable vascular access. Since bones, unlike collapsed veins, maintain their structure during severe fluid loss, the bone marrow offers a consistent pathway for infusion.
This method is endorsed in major resuscitation guidelines, including Pediatric Advanced Life Support (PALS) and Advanced Cardiac Life Support (ACLS). It is considered early in the resuscitation of critically ill adult or pediatric patients if rapid peripheral intravenous access cannot be established or has failed.
Common Intraosseous Insertion Sites
Medical professionals utilize several common anatomical locations for intraosseous device insertion, chosen for their accessibility, relatively thin cortical bone, and large marrow cavities. These sites allow for efficient delivery of fluids and medications directly into the bloodstream. The selection of a specific site can depend on the patient’s age, body habitus, and the urgency of the situation.
The proximal tibia is a frequently used site, especially in adults and older children. The insertion point is located 1 to 2 centimeters below and slightly medial to the tibial tuberosity, on the flat, anteromedial surface of the shin bone. This site is favored due to its broad, flat surface and minimal overlying tissue, making it easy to locate and access.
Another common site is the distal tibia, located near the ankle. For this site, the insertion point is approximately 2 to 3 centimeters proximal to the most prominent aspect of the medial malleolus, on the flat surface of the bone. This location is particularly useful in pediatric patients and offers an alternative when the proximal tibia is not accessible.
The proximal humerus, located in the upper arm, is another effective site, especially in adult patients. The insertion site is about 1 to 2 centimeters above the surgical neck of the humerus, on the most prominent aspect of the greater tubercle. Infusions through the proximal humerus can reach the central circulation via the superior vena cava, potentially allowing for faster delivery of substances to the heart compared to other sites.
The sternum, or breastbone, can also be used as an alternative site, primarily in specific adult scenarios, including military settings. The insertion point is 1 centimeter below the sternal notch. This site offers direct access to the central venous circulation through the internal mammary veins, providing rapid systemic distribution of medications.
What to Expect During and After Intraosseous Access
When intraosseous access is established, the procedure is swift, reflecting its emergency nature. A specialized needle, powered by a drill, is inserted through the skin and directly into the bone. Conscious patients might experience a brief, sharp pressure or pain as the needle enters the bone, though local anesthetic, such as lidocaine, is administered to manage discomfort if the patient’s condition allows.
Once the needle is properly positioned within the bone marrow, medical fluids or medications can be infused. The goal of IO access is to provide immediate support until more stable intravenous access can be established.
After the immediate emergency has passed and stable intravenous access is secured, the intraosseous device is removed. The removal involves carefully pulling the needle straight out of the insertion site. Following removal, the site will be cleaned and dressed, and medical staff will monitor the area for any signs of swelling or redness, ensuring proper healing.