In critically ill pediatric patients with difficult peripheral venous access, intraosseous (IO) access is a rapid and effective alternative for vascular administration of fluids and medications. On the other hand, drug leakage may cause skin necrosis, infection, and delayed resuscitation. Therefore, confirming correct IO needle insertion in children is crucial. Clinicians commonly confirm the correct insertion of IO access in the following three ways: (i) monitoring self‐sustaining IO access, (ii) ensuring injection without resistance, and (iii) checking for swelling around the insertion site. However, previous reports have shown that 40% of pediatric IO accesses are not appropriately placed. 1 Therefore, a more reliable method of confirming that IO access is inserted into the intrathecal cavity is needed.
Color Doppler ultrasonography, 2 microbubble detection, 3 and precordial Doppler ultrasonography 4 have all been reported as reliable methods for confirming correct placement of peripheral venous access. However, the feasibility of applying these ultrasonographic techniques to confirm IO placement remains unclear. Herein, we present the case of an infant who was evaluated to confirm IO access placement using these ultrasonographic techniques. The patient was a 1‐month‐old boy measuring height, 52.3 cm; weight, 3.9 kg. He was transferred to our hospital with a diagnosis of bacterial meningitis and admitted to the pediatric intensive care unit for further treatment. IO access was established in the proximal tibia by our transport team prior to arrival. The needle stood firmly in the bone, and fluid could easily be infused without infiltration. A bolus of 0.5 mL/kg normal saline (NS) was administered, and three different methods were applied to confirm the proper location for IO access. Method (a) is to check changes in flow velocity using color M mode, method (b) is to check microbubbles using B mode, and method (c) is to check changes in flow velocity using precordial Doppler ultrasonography. Methods (a) and (b) used transcutaneous ultrasonography (L4‐12t‐RS linear probe (Venue GO®; GE Healthcare, Chicago, IL, USA)), and method (c) used precordial Doppler ultrasonography (ES‐100 V3®, Hadeco®, Kanagawa, Japan) and recorded them using analytical software (Wave test®, Hadeco®, Kanagawa, Japan). 4 Baseline blood flow velocity was collected for the first 5 s. After NS bolus administration, blood flow velocity changes were measured for 5 s. For precordial Doppler, the IO access location was considered optimal if the change in mean blood flow velocity was 1 m/s or more between the first and second 5 s, based on a previous study. 4
We observed a change in flow velocity in the femoral vein during a transcutaneous color Doppler ultrasonography test performed immediately after NS bolus administration (Figure 1a,b). We also confirmed microbubbles immediately after NS bolus administration by B‐mode transcutaneous ultrasonography (Figure 1c,d). The precordial Doppler test revealed a change in the mean blood flow velocity of 0.48 m/s.
FIGURE 1.
(a and b) Confirmation of flow velocity changes using color Doppler ultrasonography. (a) Short‐axis image of the femoral vein before injection. (b) Short‐axis image of the femoral vein after injection. Increased flow velocity was detected in the femoral vein. (c and d) Confirmation of microbubbles using transcutaneous ultrasonography. (c) Short‐axis image of the femoral vein before injection. (d) Short‐axis image of the femoral vein after injection. Microbubbles associated with the injection were detected in the femoral vein.
Previous reports on confirming correct peripheral venous access placement have shown that the sensitivities of color Doppler ultrasonography, 2 microbubble detection methods, 3 and precordial Doppler methods 4 were 100%, 100%, and 57.1%, respectively, and the specificities were 100%, 100%, and 96.8%, respectively. The previously reported method for confirming correct IO insertion using power and color Doppler to distinguish intraosseous from extraosseous flow requires skill and shows inconsistent interpretation. 5 In addition, cases of saline turbulence in the right ventricle after IO bolus administration have been reported. 6
In this study, we confirmed that extracellular fluid administered through IO access in the proximal tibia drained through the popliteal vein and then into the femoral vein, consistent with known venous anatomy, and was detected as changes in flow velocity and microbubbles (Figure 1a–d). Our methods are simple, quick, and usable during emergencies. Unlike previous studies where bone blocked ultrasound, we investigated vessels draining from the bone marrow, allowing clearer flow observation.
However, in the present case, precordial Doppler ultrasonography did not find the ≥1 m/s difference in the blood flow velocity (0.48 m/s). In previous reports, 4 when the change in Doppler flow velocity was <1.0, 20% (4/20) had peripheral intravenous infiltration and dysfunction. This discrepancy may reflect a reduction in flow velocity caused by increased resistance as the injectate traverses pathways from the intraosseous cavity into the venous system as well as the relatively long distance between the bolus administration and detection sites.
Detection of color Doppler ultrasonography changes and microbubbles in the femoral vein may be useful for confirming correct IO access placement in the proximal tibia. However, in this case, precordial Doppler ultrasonography could not determine the correct IO access placement. This is a single case report, and further study is needed to improve generalizability.
AUTHOR CONTRIBUTIONS
The study was designed by Tomoki Ueda, Yuji Hirayama, Tomoya Ito, and Taiki Kojima. Tomoki Ueda drafted the paper. All authors revised the manuscript and contributed to the final approval of the final version of the manuscript.
FUNDING INFORMATION
The authors received no funds, grants, or other support regarding this research.
CONFLICT OF INTEREST
The authors have no conflict of interest to disclose.
INFORMED CONSENT
This study plan was approved by the ethical committee of our institution (approval number 2024024, June 10, 2024). Written informed consent was obtained from the parents of the study participant.
ACKNOWLEDGMENTS
We thank Editage (https://www.editage.jp) for the academic language editing service.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available upon request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data that support the findings of this study are available upon request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.