The Critical Pathway From Cardiac Arrest To Trauma Resuscitation

Introduction: Challenges in Vascular Access in Adult Emergency Care
In the adult emergency care environment, especially in critical situations such as cardiac arrest, severe trauma, and shock, quickly establishing a reliable vascular access is one of the key prerequisites for successful resuscitation. However, under these extreme physiological conditions, traditional peripheral venous access often becomes extremely difficult or even impossible due to vessel collapse, low blood volume, and peripheral circulatory failure. Central venous catheterization is reliable, but it requires high technical skills, has a high risk of complications, and is often impractical in the urgent time frame of emergency care. The intramedullary access needle has been rediscovered under this clinical challenge and has re-established its core position in adult emergency care.
Cardiac arrest: Time is myocardium, and the pathway is life.
During cardiopulmonary resuscitation for cardiac arrest, every minute of delay in defibrillation results in a 7-10% decrease in survival rate. And the delay in drug treatment is equally fatal. Traditionally, medical staff often delay the administration of critical drugs (such as epinephrine) when attempting to establish an intravenous access. Modern guidelines clearly state: If a reliable peripheral venous access cannot be established within 90 seconds, the procedure should be immediately switched to an intravenous access in the bones.
The unique advantages of using IO in cases of cardiac arrest include:
1. Does not interfere with resuscitation procedures: The IO pathway established through the humeral head completely does not affect the ongoing chest compressions. This is incomparable to the internal jugular or subclavian vein pathways.
2. Pharmacokinetic advantages: Drugs administered through the bone marrow cavity quickly enter the central circulation via the nutrient veins. Studies have shown that the time to reach peak concentration when administering epinephrine through the IO is not significantly different from that of central venous administration, and the blood concentration curves are similar.
3. High first-time success rate: Even in patients with cardiac arrest, the first-time success rate of IO puncture still exceeds 90%, while the success rate of peripheral venous puncture is often below 50%.
4. Compatibility with multiple drugs: The IO pathway can safely administer all resuscitation drugs, including epinephrine, amiodarone, lidocaine, sodium bicarbonate, etc., with no reported drug compatibility contraindications.
Standard Operating Procedure Recommendation: After identifying cardiac arrest and initiating cardiopulmonary resuscitation, the first team is responsible for providing continuous high-quality chest compressions and early defibrillation, while the second team should simultaneously attempt to establish an intravenous access. If the first peripheral venous attempt fails or is expected to be difficult (such as for patients using intravenous medications, obese individuals, or those with edema), repeated attempts should not be made; instead, an IO access should be immediately switched to.
Trauma resuscitation: Control the injury, rapidly expand blood volume
Patients with severe trauma often suffer from hypovolemic shock. At this time, the peripheral blood vessels are severely constricted, making it extremely difficult to establish an intravenous access. The principle of damage control resuscitation (DCR) emphasizes early, rapid and balanced fluid resuscitation, which entirely relies on reliable vascular access.
In trauma resuscitation, the value of the IO pathway lies in:
1. Not affected by vascular condition: Even when the systolic blood pressure drops to 40 mmHg, the vascular structure of the bone marrow cavity remains open and the pathway function is not affected.
2. Multiple site selection: Choose the puncture site flexibly based on the trauma situation. For lower limb trauma, the humeral head can be selected; for upper limb trauma, the proximal end of the tibia can be chosen; for pelvic fractures, the contralateral tibia or humerus can be selected.
3. Rapid infusion capability: The modern IO system, combined with a pressurized infusion device, can achieve a flow rate of over 125 mL/min, meeting the needs for rapid volume expansion. Through a dedicated IO catheter (such as 15G EZ-IO) and a pressurized bag, the flow rate can even reach 250 mL/min, approaching the level of large-diameter peripheral veins.
4. Blood product infusion: Studies have shown that infusing blood products such as red blood cells, plasma, and platelets through the IO pathway is safe and effective. Some degree of hemolysis occurs when blood passes through the bone marrow cavity, but the clinical impact is limited. For trauma patients requiring large-volume blood transfusion, IO can be used as the initial pathway, while preparing a more durable central venous pathway at the same time.
Considerations for the Application of Special Adult Patients
For certain adult patient groups, establishing an intravenous access can be particularly challenging. In such cases, the implantable port (IO) is often the preferred or first choice option.
- Obese patients: Patients with severe obesity (BMI > 40) often have deep and inaccessible veins. The bony landmarks are relatively unaffected by obesity, and the puncture success rate remains high. However, a longer needle (such as the 45mm EZ-IO needle) should be used.
- Intravenous drug users: Long-term intravenous drug users with hardened, thrombosed, and infected peripheral veins cannot use this method. The bone marrow cavity approach is not affected by these conditions.
- Burn patients: Patients with extensive burns have limited puncture sites and often suffer from severe edema. The bone position is relatively constant and is a reliable choice. However, care must be taken to avoid puncturing through the burned skin to prevent the spread of infection.
- Elderly patients: Osteoporosis may increase the difficulty of puncture, but the driving force of modern IO devices can be adjusted to adapt to different bone densities. The bones of elderly patients are more brittle, and care must be taken to avoid puncturing too deeply, which could cause penetration of the opposite cortical bone.
- Pathological edema patients: Patients with severe heart failure or kidney failure have generalized edema, and the venous landmarks disappear. The bone position is not affected by edema, making it an ideal choice.
Special considerations for drug infusion
Although almost all resuscitation drugs can be administered via IO, there are certain drugs that require special precautions:
- Hypertonic solutions: such as hypertonic saline, mannitol, may cause pain in the bone marrow cavity. Pre-medication with lidocaine (via the same IO route) or slow infusion of diluted solution can be considered.
- Vasopressor drugs: epinephrine, norepinephrine, etc. can be safely administered through IO. However, it should be noted that at extremely low flow rates, the drugs may remain in the bone marrow cavity for a short period of time, and when the circulation suddenly resumes, a large amount of the drug may enter the bloodstream all at once, causing a sudden increase in blood pressure. It is recommended to start with a small dose and closely monitor.
- Antibiotics: all commonly used antibiotics can be administered through IO. There is a theory of bone marrow infection risk, but the actual incidence is extremely low (<1%) and is related to the duration of the indwelling.
- Contrast agents: iodine contrast agents for CT scans can be administered through IO, but a pressurized syringe should be used and the infusion rate is slower than that of intravenous infusion. Studies have shown that the imaging quality is acceptable.
Prevention and management of complications
The incidence of adult IO complications is approximately 1-2%, and they mainly include:
- Infiltration at the puncture site: The most common issue, often due to the needle tip not being fully within the bone marrow cavity or the puncture being made on the opposite bone cortex. Treatment: Stop the infusion, remove and replace the site.
- Fracture: Rare, usually occurring in individuals with severe osteoporosis or with improper puncture technique. Prevention: Choose a site with better bone quality and avoid puncturing at the original fracture site.
- Tendon sheath syndrome: The most severe but rare condition, caused by a large amount of rapid infusion extravasating into the tendon sheath. Prevention: Avoid using overly long needles, ensure the needle tip is in the correct position, and monitor the puncture site. Treatment: Immediately remove the needle, and if necessary, perform fasciotomy for decompression.
- Infection: Occurs in <1% of cases and is related to the duration of indwelling. Prevention: Strict aseptic procedures, transfer to a venous access as soon as possible, and keep the indwelling for no more than 24 hours.
- Fat embolism: Theoretical risk, but actually rare. Prevention: Avoid excessive flushing to prevent high pressure.
The Importance of Training and Simulation
Although IO puncture is a relatively simple technique, it requires appropriate training and continued proficiency. Simulation training is crucial and should be conducted using real IO equipment and simulated bones (or animal bones). The training focuses include:
1. Accurate identification of anatomical landmarks
2. Correct assembly and use of equipment
3. Mastery of puncture angle
4. Confirmation of needle tip position (feeling of missing, stable needle holder, smooth aspiration)
5. Connection and fixation of tubing
6. Identification and handling of complications
Studies have shown that through systematic simulation training, the first-time success rate of IO puncture can be increased from about 60% for beginners to over 90% for experienced practitioners, and the operation time can be shortened from several minutes to 30-60 seconds.
Conclusion: The Transformation of Emergency Thinking Mode
The widespread application of intramedullary access in adult emergency care represents a shift in clinical thinking: from "trying to find veins" to "ensuring any effective access". It acknowledges the limitations of traditional methods under extreme physiological conditions and provides a reliable, rapid, and easy-to-master alternative. In critical moments such as cardiac arrest, severe shock, and multiple trauma, IO access often means a second chance. With equipment improvements, evidence accumulation, and training dissemination, IO is evolving from a "last resort" to an "early choice", becoming an indispensable basic skill in modern adult emergency medicine, truly embodying the emergency concept of "establishing the correct access at the right time for the right patient".