Intraosseus (IO) has long been an important method to access the central circulation in cases of difficult peripheral IV access. The first widespread use of IO was to treat hemorrhagic injuries during World War II.1 Now, IO access has become the standard of care for pediatric resuscitation.2
New technologies have made IO access in adult patients easier and more common. Currently, the American Heart Association and the European Resuscitation Council recommend IO access as the primary alternative in cases of failed IV, replacing endotracheal administration of fluids and medications.3,4 The National Association of EMS Physicians recommends that EMS agencies provide at least one method of IO access for pediatric and adult patients.5 And EMS medical directors have been urged to consider use of IO route for patients requiring immediate vascular access.6
Typically, the head of the tibia bone is used for IO access. Montgomery County Hospital District (MCHD) EMS conducted an observational study to determine the feasibility of the humerus bone as an additional anatomical site. As part of our study, we examined the experiences of our EMS personnel in using a powered IO access device at both anatomical sites.
Study Methods & System Background
The study protocol was classified as exempt by an Institutional Review Board. The study participants were ALS EMS providers (EMT-Is and paramedics). All participants completed a training program on the use of a battery-powered IO access device that uses a hand-held, battery-powered drill with a specialized tip to insert a hollow needle into the IO space.
The training included background lectures, anatomical landmark identification techniques, specific training on the use of the device in the proximal humerus and a hands-on workshop. Participants also received periodic training updates. EMS personnel reporting unsuccessful IO insertions received additional training as necessary.
MCHD EMS covers an area of approximately 1,100 square miles north of Houston.
The service employs more than 160 uniformed field staff, operates a fleet of 24 emergency vehicles and responds to more than 30,000 calls a year.
The service has used the device since 2004. All MCHD EMS response vehicles were equipped with the IO device, including the powered driver, needle sets, and IV tubing and connectors.
The study period ran from December 2005 to July 2006. Eligible patients were in need of immediate vascular access and weighed more than 40 kg. IO vascular access was the first-line procedure in cases of cardiac arrest and resuscitation. In other cases, EMS providers were required to call in to on-line medical control for permission to use IO access.
Providers were instructed to use the humeral site when available. However, the ultimate decision on which anatomical site to use rested with those attending to the patient. If providers chose the tibia for IO infusion, they were required to identify the reason they chose it over the humerus.
Patients were classified into two groups. Patients in the humerus group received IO insertion in the proximal humerus bone as the primary choice for vascular access. This group also included patients in whom IO vascular access couldn’t be attained via the humerus but was later achieved via the tibia as a rescue site. Patients in the tibia group received IO insertion via the tibia as the primary choice for vascular access.
Insertion success was defined as successful vascular access in a patient at either anatomical site. Multiple insertion attempts were allowed. Insertion success was determined for each anatomical site as successful vascular access without resorting to the alternate site.
EMS personnel were asked to estimate the time to locate the insertion site and the time to IO needle insertion on questionnaires completed after care.
The time to locate the anatomical insertion site was estimated as the time to identify the specific insertion site after the skin over the site was exposed. The time to IO insertion was estimated as the time from hand placement on the powered driver by the EMS provider until the time the needle was placed in the IO space, ready for infusion.
EMS personnel rated ease of site location and ease of needle insertion with a modified Likert scale (1 to 10; 1 being easy, and 10 being most difficult). Data were collected from completed patient records during the study period.
Patient characteristics are shown in Table 1 (see August issue JEMS,p. 54). IO infusion was attempted in 120 patients: 20 in the humerus group and 100 in the tibia group. The overall success rate was 75% (15 of 20) for patients in the humerus group and 92% (92 of 100) for the tibia group, with five insertion failures in the humerus group. IO vascular access was later achieved via the tibia for four of these patients.
In the tibia group, repeat attempts were required for 11 patients. This included two patients with no fluid flow after either attempt, three patients with two successful placements during CPR, four patients who required a second tibial placement due to dislodgement or no fluid flow from the first placement and two patients for whom the reason isn’t known.
Times to locate the anatomical insertion site and times to IO needle insertion are shown in Table 2 (see August issue JEMS pg. 55). EMS personnel located the insertion site on the humerus bone within 30 seconds for 95% of patients in that group. Similarly, they identified the insertion site on the tibia within 30 seconds in 84% of patients in the tibia group. Insertion times were less than 30 seconds for 95% of patients in the humerus group and 76% of patients in the tibia group. Ease of use was rated as 3.6 ± 1.9 for the humerus group and 1.5 ± 0.9 for the tibia group.
The most frequent reason cited for choosing the tibia over the humerus was “too much activity at the torso” (See Table 3 August issue JEMS, p. 56). Other reasons reported were easier identification of the tibia anatomical landmarks, too much fat overlaying the humerus and inability to expose the humerus access site. No complications, such as osteomyelitis, extravasation, displacement or device failure, were reported for either group.
Vascular access is critical in emergency care, because it’s essential for administering medications and fluids during resuscitative maneuvers. IO vascular access is valuable when traditional IV access is difficult or impossible.
In this study, the proximal humerus was shown to be a feasible option for IO infusion of drugs and fluids. We found that the overall insertion success was lower for patients in the humerus group than in the tibia group (75% versus 92%, respectively).
Notably, all five insertion failures in the humerus group occurred the first time an EMS provider used the device at the site. Also, first-time users of the device often chose the more familiar tibia site over the humerus for IO vascular access.
When the investigators asked the EMS personnel their reasons for choosing the tibia insertion site over the humerus, the most frequent reason cited was “too much activity at the torso” (38% of respondents).
Other reasons were ease of location of anatomical landmarks at the tibia (19%) and excess fat tissue at the humerus (12%). The most frequent reason for choosing the humerus over the tibia was “to satisfy study requirements” (20%).
In one case, the provider chose the humerus over the tibia because the patient had below-the-knee amputations in both legs. As EMS personnel users gain more experience with IO insertion at the humerus, the investigators feel that the success rate will approach the 90%-plus success rates reported for the tibia site.7,8
Two recent studies confirm the utility of the humerus as an anatomical site for vascular access. One study compared the humerus and the tibia for IO access using the same device as the current study.9 They reported a 100% success rate for needle placement in 11 humerus and 24 tibia insertions, although a second attempt was required for one of the tibia insertions. Flow rates and ease of insertion were similar for both sites.
Another study compared IO infusion at the humerus to peripheral IV catheters and central venous lines in trauma and medical resuscitation patients in the emergency room setting.
see August issue JEMS
They found that mean time to vascular access was significantly quicker for the IO device at the humerus (1.2 ± 0.4 min) than with traditional IV lines (3.6 ± 3.3 min, p < 0.0001) or central venous lines (15.6 ± 5.8 min, p = 0.005). Patients reported the perceived pain to be similar across all three vascular access techniques.
The success rate in attaining vascular access observed at the humerus in the present study is greater than traditional IV access. Success rates for IV access are relatively lower.11,12 In one study of difficult IV access, defined as three or more unsuccessful attempts, physicians reported only a 33% success rate with conventional IV access with attempts averaging 30 minutes.11 This was improved to 97% when physicians used ultrasonic guidance to place the IV catheter, although this isn’t always feasible in EMS.
IO access via the humerus or tibia can also prevent potentially deadly delays in vascular access. Insertion of a peripheral venous line can delay vascular access up to 10 minutes, causing undue pain to the patient and consuming valuable time and EMS personnel.13 Peripheral venous access in pediatric patients can take several minutes or more, despite proficiency on the part of EMS providers.
A 1985 study reported IV insertion times to be greater than 10 minutes in 24% of pediatric emergency patients, with complete failure of vascular access in 6% of cases.14 As such, IO vascular access provides a reliable and faster alternative that may benefit many critically ill patients.
The current anatomical sites for IO vascular access are the tibia, the sternum and the humerus. Choice of site depends on patient age and device type. The tibia is the most popular site for pediatric patients.13
The sternum is currently favored in military medicine because of the prevalence of lower-extremity-related injuries. However, this may change with the recent FDA clearance of a device that allows for insertion into the proximal humerus.15
Scientific rationale for humeral IO placement include reduced time to central circulation, tighter bolus doses and concerns about lower-extremity trauma, as well as abdominal and retroperitoneal injuries. Clinical studies, as well as preclinical studies in animal models, demonstrate that drug delivery to the heart from the IO space of the humerus is equivalent to central lines.16,17
The humerus is often favored for IO vascular access by air-medical transport emergency personnel because of easier access to the upper body. Space constraints within helicopters sometimes restrict physical access to lower extremities.
Proper site selection for vascular access is crucial in military medical settings. According to the Textbook of Military Medicine, two-thirds of battlefield casualties involve extremity wounds that could preclude IO insertions in the injured extremity.19
In the case of injury to the arm, the proximal humerus would still be well above most fractures or vascular injury sites.
Another advantage of the humerus over the tibia is that IO vascular access through the tibia requires travel of infused fluids or medications through the circulatory system of the thigh and pelvis, which are potential places for major blood loss.
Many patients may benefit from the availability of the humerus as a vascular access site. These include those with extensive lower-extremity trauma, or pelvic or abdominal injuries where efferent vessels may be damaged.
Patients requiring large amounts of fluids may also benefit because the proximal humerus allows for higher flow rates than the tibia in most cases.
The use of the humerus precludes the need to remove protective armor (e.g., bulletproof vests), thus saving valuable time and protection.
The humerus may also be useful for patients with titanium knee implants or excess fatty tissue covering the tibia. One advantage for the humerus over the sternum is that it provides two access sites above the diaphragm and may allow for uninterrupted CPR during vascular access attempts.
Few complications have been reported for IO infusion. Typical complications may include extravasation and occasionally osteomyelitis. No complications were observed in the current study. In contrast, peripheral IV catheterization is associated with high rates of complication.
One study of 609 patients with indwelling peripheral venous catheters for 24 hours or more found that 19.7% of patients developed phlebitis, 6.9% developed catheter-related infection, and 6.0% experienced catheter obstruction.20
This observational study demonstrated that the proximal humerus bone is a viable anatomical site for IO vascular access. For those patients with successful IO access at the humerus site, the needle was correctly placed within 30 seconds. EMS providers found both sites to be useful for IO access, although they tended to prefer the tibia over the humerus.
The humerus provides an acceptable alternative insertion site, which may be preferable under certain clinical scenarios, such as lower body trauma or amputation. JEMS
This article originally appeared in August 2010 JEMS as “Alternate Route: Is the humerus bone a viable alternative for IO access?”