Читать книгу Emergency Medical Services - Группа авторов - Страница 206

IO devices function to access the intramedullary vessels found in the marrow of spongy bone that lead to the central circulation of the body. The IO needle, embedded in the bony structure, is protected by the noncollapsible periosteum, solving any problems with patency that may be encountered with IVs during vasoconstriction and low‐flow states found in, for example, sepsis and cardiac arrest.

IO access is currently attainable with manual, impact‐driven, and powered drill methods. The gauge and length of some of the commercially available products vary for adult and pediatric patients. The commonly available EZ‐IO^TM uses a 15‐mm‐long needle for children under 39 kg, while 25‐mm and 45‐mm lengths are available for patients 40 kg or greater. All are 15 gauge. The sites of insertion vary by manufacturer recommendations, but locations may include the proximal tibia, distal tibia, proximal humerus, and sternum. Contraindications to IO access are generally site specific and include infection of the overlying skin, fracture at or above the IO site, vascular compromise, and previous surgery or significant deformity of the bone. Previous sternotomy, suspected sternal fracture, and CPR with chest compressions preclude sternal IO access. Potential complications include osteomyelitis, fat emboli, fracture, growth plate injury, compartment syndrome, infection, and extravasation resulting in local tissue injury and swelling [15–17].

Drinker and Lund in the 1920s were the first to use IO vascular access in the sternum of animal models, demonstrating that the fluid given did indeed reach intravascular circulation. Josefson followed in 1934, reporting the first IO use in humans. Soon after, in the 1940s, the first use of the IO was documented in the pediatric population. While its use among military personnel during WWII was advocated when IV access was delayed or difficult, the development of the over‐the‐needle PVC IV catheter by Massa in the 1950s temporarily curtailed use of the IO. The reemergence of the IO in the 1980s in the Pediatric Advance Life Support and Advanced Pediatric Life Support courses supported its use after failed IV attempts. More recent guidelines from the American Heart Association advocate for the use of IOs as first‐line access in pediatric emergencies and as the first alternative in adult cardiac arrest, including in out‐of‐hospital settings [13, 15, 16, 18].

Several studies have demonstrated the success of obtaining vascular access through IOs after failed or difficult attempts at IV access. IO vascular access has demonstrated high first‐attempt success rates and overall success rates of 90% and greater in adults and children [17]. The advantages of the commercially available battery‐powered driver used in the study included its short learning curve, ability to easily penetrate thick cortical bone given its power source, and rapid drug delivery into the systemic circulation [19]. IO access has been proven to be as quick and effective as IV access [20]. In patients with inaccessible peripheral veins, IO access is faster and more successful than central IV lines [21].

Most medications given through the peripheral IV can be given through an IO, with bioequivalence proven between the two routes [22]. IO has been shown to have clinically comparable time to peak drug concentration as compared to central IV access [18].

Wilderness, tactical, disaster, and other specialty EMS groups may encounter situations requiring early consideration of the use of the IO for vascular access. Austere conditions, limited access to an entrapped patient, or cumbersome gear and clothing of both patient and clinician can inhibit efforts to initiate peripheral IV access. One study demonstrated significantly shorter times to IO access compared to IV access when EMS clinicians donned chemical, biological, radiological, and nuclear protective equipment [23]. IO access is recommended during any resuscitation when IV access is not attainable [15].

Pediatric IO placement mirrors the adult procedure with minimal additional considerations. As IV access in a critically ill child can be difficult and anxiety provoking for the EMS clinician, many pediatric emergency practitioners elect to use IO after fewer failed attempts than would be tolerated in an adult. Additionally, IO placement in a moving child requires less fine motor dexterity than IV catheter placement and may be successful when traditional calming and redirection techniques are unsuccessful. The pediatric patient also offers several additional sites for placement, such as the distal femur and the iliac crest. However, as these sites are not commonly used in adults, training and protocols may be more effective using similar anatomical landmarks across all patients.