This study set out to examine paramedic success of proximal humerus intraosseous (IO) placement, using the power assisted EZ-IO device, in out-of-hospital cardiac arrest in adult patients.
The researchers achieved this by retrospectively analysing data collected as part of a previous study that investigated the impact on patient outcomes of early use of adrenaline.
Paramedics who were skilled at tibial IO access participated in 90 minutes of training to learn about indications, contraindications, landmark identification and insertion techniques for humeral IO placement. This incorporated some practical work, as well as didactic delivery, to gain experience at humeral insertion in a simulated environment. To supplement this education, paramedics were given access to an online video for reference. In the study itself, although the protocol determined that humeral access was the preferred route (maximum of one attempt per bone), the paramedics maintained autonomy to make clinical decisions as to use of alternative access routes, if required, according to the patient's clinical situation.
Data taken from the original prospective study included patients’ demographic data; identified insertion site; number of attempts made; time from arrival at patient to successful IO placement; total volume of infused fluid; and any documented complications. This data was collected immediately after the cardiac arrest in a post-event debriefing.
The primary outcome measure was successful placement at the first attempt —this was defined as the paramedic, on their first attempt, achieving stable IO access which supported administration of fluids/medication without any signs of extravasation.
Analysis focused on descriptive statistics providing percentages to indicate success and failure rates. However, the reader of this paper needs to be aware that there are some numerical inconsistencies when comparing what is reported in the text and what is presented in the figure and table. One example of this is where the study states, both in the abstract and body of the text, that humeral access was attempted in 247 (61 %) cases but Table 1 and Figure 1 indicate that humeral access was attempted in 244 (60 %) cases. Another example of inconsistency lies in the abstract, in which 2 % of failed cases were attributed to obesity but in Table 1 the researchers identify this percentage as 1 %. Although this calls in to question the accuracy of some of the specifics of the calculations, there is clearly a trend towards a high level of successful insertion when using the humeral IO route. In total, during the nine months that were included within the study, 405 resuscitation attempts were undertaken. There was an identified success rate of 91 % at the first attempt, rising to 94 % at the second. Overall, the failure rate was reported as low and additionally, there were only four reports of successful placement with subsequent dislodgement.
The authors identify several limitations to the study, some of which are common issues confronting retrospective research; additionally the data was based on self-reports given by paramedics in a post-resuscitation debriefing event.
The authors conclude from their study that the success rate of IO insertion into the proximal humerus by paramedics was high and there were relatively few complications. However, future research should include evaluation of other IO devices to see if there are similar levels of success.
As indicated earlier, the inconsistencies in the numerical data of the study need to be corrected before readers can consider, with any degree of confidence, the actual implications of this piece of research for paramedic practice.
