骨髄針の配置

Intraosseous, or IO, needle placement is one of the methods of establishing vascular access quickly for unstable patients requiring urgent administration of medications, fluids or blood products. IO needles allow rapid and technically straightforward access to the highly vascularized intramedullary space inside the long bones. From there, medications and fluids are readily absorbed into the bloodstream, allowing the stabilization of critically ill patients.

In this video, we will first discuss the indications, considerations, and contraindications for IO placement, followed by the procedure that demonstrates the use of an intraosseous drill.

Another conventional method for establishing vascular access is placement of a peripheral intravenous cannula, or PIV, discussed in another video of this collection. However, PIV placement may be technically challenging in: small children, injection drug users, obese people, patients with chronic illnesses necessitating frequent vascular access, patients with burns and other skin conditions, and patients in shock in whom blood is shunted away from the periphery in order to compensate for impaired perfusion of vital organs. In addition, failure of PIV attempts is extremely common. Therefore, in severely ill patients with urgent need for vascular access, IO needle placement is an extremely effective alternative.

The first step in the placement of an IO needle is site selection. The location options include the proximal tibia on the medial flat side at the level of the tibial tuberosity. In adults, this spot is about three cm distal to the inferior border of the patella. Another site is the distal tibia. Again, on the medial flat side, but three cm proximal to the medial malleolus. The third option is the proximal humerus, on the most prominent aspect of the greater tubercle, which is 1-2 cm proximal to the surgical neck. There is no compelling evidence that one site is uniformly “better” than another in terms of efficacy or patient comfort. However, the proximal humerus is the preferred site in patients with abdominal, pelvic or lower extremity trauma.

In the absence of any trauma, site selection is based on patient size, anatomy, indication for insertion, provider’s ability to identify anatomic landmarks, provider’s experience and comfort, and, of course, absence of contraindications to use of a specific site. These contraindications to use of the chosen location include: acute or recent fracture of the target bone, previous significant orthopedic procedure at the target site, overlying skin or soft tissue infection, inability to appreciate anatomic landmarks by patient palpation and previous IO needle placement at the site within the past 48 hours.

Now let’s review the IO needle placement procedure that utilizes an intraosseous drill

First step is positioning. For tibial insertions, put the patient in a “frog leg” position, with the knee slightly bent and abducted, allowing access to the medial aspect of the tibia. For humeral insertions, adduct the patient’s elbow and rest the forearm across the abdomen, which will internally rotate the humerus, moving the tubercle into an anterior position. Palpate thoroughly to identify the insertion site, in this case the most prominent aspect of the greater tubercle. Remember, you will not be able to touch the site once it has been cleaned, so make sure you know exactly where you plan to place the needle.

Next, cleanse the insertion site with the antiseptic solution, like chlorhexidine. While the antiseptic solution is drying, prepare your equipment. Test to make sure that the intraosseous drill is charged and functional. Next select the appropriate needle. 15 mm is for infants and small children, 25 mm is for larger children and adults, and 45 mm is for unusually large adults. Note that the needles have black markings every 5 mm from the tip to the top of the shaft. In addition, ensure you have the connector set for flushing and administration of medication or fluids, and the dressing material to stabilize the needle once inserted.

Start by attaching the needle to the drill by simply clicking it into place. Stabilize the patient’s extremity with your non-dominant hand, making sure not to contaminate the insertion site. Aim the needle at a 90-degree angle to the center of the bone. Push the needle tip through the skin at the chosen insertion site, and let it rest against the bone. Ensure the first 5 mm mark is visible above the skin surface. If it is not, use a longer needle to ensure adequate length to reach the medullary space.

Next, begin drilling holding the needle steady and applying the gentlest possible pressure. Watch and feel carefully. When the needle enters the medullary space, you will feel it “give way” as the high resistance of the mineralized cortex changes to the much lower resistance of the soft marrow. Note that this sensation is much less prominent in young children, whose bones remain cartilaginous. As soon as you feel the “give,” stop drilling and note the position of the needle. If you feel resistance again, then you may have reached the on the other side of the medullary space, and continuing may cause the needle tip to lodge into the far cortex.

Remember, your goal is not to get the hub of the needle against the skin, which may result in excessively deep insertion. Your goal is achieve total needle depth of 1-2cm, with tip seated in the medullary space. This will usually, but not always, result in the hub ending up next to the skin if the proper needle has been selected. Hold the hub in place while gently pulling the driver straight off the needle. Continue holding the hub while gently twisting the stylet counter-clockwise, to take it off the hub. Then pull the stylet out of the hollow-bore needle and discard it into a sharps container. Next, verify the needle feels firmly seated in the bone. If it moves easily, then it is in the subcutaneous tissue. When you are satisfied that the needle is firmly seated in the bone, stabilize and protect the needle by securing it with gauze and tape, or a purpose-made stabilizer dressing. Then attach a primed connector set and a 5-10 millimeter flush syringe into the needle hub.

Verify the IO needle is properly positioned and functional by aspirating the needle. You will usually, but not always, see pink marrow reflux into the tubing. Further verify the functionality of the IO needle by flushing. You should never see leakage of fluid around the insertion site, and the patient’s skin should not become puffy. You may experience some resistance while flushing, especially at first, but it should not be difficult to infuse the full syringe of fluid into the medullary space.

For pediatric patients and adults who are unresponsive to pain, the IO needle is now ready to use. Remember, anything that can be infused into a central venous catheter can also be infused into an IO needle, including fluids, blood products, bolus medications and continuous infusions; but the infusions must be pressurized to flow effectively. Be sure to frequently assess the patient for signs of extravasation, malposition or any other complications.

For adults who are responsive to pain, 2% intravenous, preservative-free, lidocaine may be used to anesthetize the medullary space. For details regarding the lidocaine dose, infusion method and threshold of toxicity, see the text protocol below.

You have just watched a JoVE video detailing the steps necessary to place an IO needle. In cases where traditional intravenous access cannot be secured, IO access is a rapid, safe, and effective alternative. The commercial availability of the IO drills has made this traditional pediatric procedure feasible for patients of all ages. It is a technically simple procedure that can readily be mastered by healthcare workers, and used to save lives! As always, thanks for watching.