One of the most commonly cited fears associated with IO placement is osteomyelitis. Research has shown that, with proper sterile technique during initial placement, the actual risk of this infection is only 0.6% and potentially even less if the device is removed promptly.28--30 Another common concern centers on the potential inhibition of bone growth, but this concern appears entirely unfounded. 20,29,31--32 Micro-fat emboli can occur with placement of an IO line and fluid administration; however, this has not been shown to be a clinical problem.30,33
Infiltration and subsequent compartment syndrome is a definite concern with IO infusions. If undetected, it can result in local tissue death and even loss of the limb. This is especially significant if caustic medications like dopamine were infusing.12 The key to avoiding these complications is regular and repeated assessment of the IO site and surrounding tissues. If any infiltration is detected, the IO infusion should be discontinued immediately. In addition, if an IO device insertion has been unsuccessful, or if one has been removed, it is essential that all caregivers are aware of the situation so that no further IO attempts are made on that same bone.
Effectiveness of IO vs. IV Access
When an IO is correctly placed, fluid and medications can be administered just as if an IV line was in place. The intraosseous space is a specialized area of the vascular system. Resting pressure in the intraosseous space (10--35 mmHg) is generally a value between mean arterial pressure (50--100 mmHg) and venous pressure (0--10 mmHg). Though fluid may flow to gravity into an IO line, the flow rate for bolus infusions can be optimized if a syringe or pressure bag (inflated up to 300 mmHg) is used. Utilizing these methods, flow rates in excess of 40cc/min (2,400cc/hr) can be achieved, and a pediatric 20cc/kg fluid bolus can be given over 5--6 minutes.24 A study using a sternal IO device reported a remarkable gravity flow rate of up to 80cc/min and delivery of more than 150 cc/min by syringe bolus.34
Whether it's administered by IV or IO routes, one of the key factors is the amount of time that it takes for the medication to reach the central circulation. Studies have shown that medications given via an IO infusion reach central circulation just as fast, if not faster, than when administered by standard IV access.1,4,35,36 As for which medications can be administered through the IO device, the answer is simple: Anything that can be given by IV--from blood products and analgesics to antibiotics--can be given by IO effectively.12,26,36
The ideal device or needle should be small, lightweight, reloadable, inexpensive and easily inserted under any conditions. Again, the IO technique is not advocated as a replacement for conventional IV techniques. Instead, it should be considered as a viable alternative under emergency situations in which gaining vascular access is imperative, but conditions make it extremely difficult for even the most experienced health provider to obtain IV access.4
IO Device Options
Currently, there are several different devices available for placing an IO line. These devices range from familiar manually inserted spinal needles to impact-driven devices and power drills. Prior to the creation of products specifically designed for IO access, spinal needles and "butterfly" needles had been used. When using a spinal needle, it is essential to use one that has a removable stylet or trocar, which will keep the needle from becoming plugged by tissue during initial placement.
Historically, the most popular IO needles used with pediatric patients (and in rare cases, adult patients) have been the Jamshidi/Illinois (Figures 3 and 4, Cardinal Health, McGaw Park, IL) or Sur-Fast (Figure 5, Cook Critical Care, Bloomington, IN) types. These devices are introduced by using a turning or screwing motion with sufficient downward pressure to allow the needle to bore into the bone. Recently, introduction of the next generation of IO access began with an exploration of the expanded potential patient population, an examination of IO sites beyond the tibia, and research into newer IO infusion devices.12,19,24,30,33,37--40