Ultrasound-assisted bony landmark palpation in untrained palpators

Methods

The Kansas City University Institutional Review Board approved the research study, which was supported by an intramural grant funded by Kansas City University.

A total of 166 first-year medical students were recruited and given the opportunity to participate in the study during their orientation weeks via email and flyer announcement and through open enrollment. Thirty-two students volunteered and consented to participate. The study participants were all first-year osteopathic medical students in their first week of orientation, before the start of any osteopathic palpatory training. Demographic information such as age, sex, and previous profession was not collected. The data were collected in a single session at the end of the first-year medical students’ orientation weeks. The study was performed in the osteopathic manipulation laboratory at the Kansas City University-Joplin Campus, with the study area hidden behind a wall partition.

In the first station, the subjects were brought into a partitioned area with a manipulation table, skeletal spine, and laptop with an instructional video (Figure 1). Study participants were asked to watch an instructional video showing relevant anatomy and locations of the bony landmarks relevant to the study, as well as a demonstration of palpation and location marking with an invisible ink marker (Video 1 [https://kansascity.box.com/s/z33gqcyz74rffu0a1nvqa9m6mjkiinmf]). The participant was then asked to practice on a spinal skeleton on their table. After watching the video, the participants were then instructed to palpate the prone human subject and mark a single dot (not circle) on any transverse process located between the shoulder blades. No time restriction or limit was given to the participant for any part of the study, so the participants went through the video and study at their own pace. A proctor was available to hand an uncapped, invisible ink marker to the patient, and the proctor was advised to give no instruction to the participants other than to redirect the subject if they were palpating outside the control area (T2–T9). There was no confirmation or adjustments made by the proctors to redirect participants if they were not on a transverse process. After marking, the subject then returned to station 1 and played the instructional video, which demonstrated ultrasound probe usage, basic technique, and identification of landmarks with ultrasound. The subject was then asked to return to station 2, where the proctor had a Butterfly IQ+ probe ready with gel, hooked up to an iPad, set on MSK mode, with a depth of 6–7 cm (Figure 2). The research assistant handed the subject the probe, and allowed the subject to locate their landmark, and then the research assistant was ready with an uncapped invisible ink marker of a different color to allow the subject to make their second mark. The proctor was instructed to not give any feedback, tips, or communication other than instructing the subject where to go and to redirect the subject to the control zone for palpation if needed.

Figure 1:

Station 1: Partitioned area with table, stool, laptop with study video, prone skeleton, and hand sanitizer.

Figure 2:

Station 2: Partitioned area with prone study volunteer patient palpatory model.

After the subject left the area, the proctor visualized the invisible ink markings utilizing an ultraviolet flashlight. The control markings for the transverse processes were done prior to the study by board-certified clinician with experience in ultrasound diagnostics and procedures. Control markings were done with an invisible ink marker in the color blue. The color blue was utilized, because it was found to be resistant to wiping off with alcohol. The clinician marked the most posterior (superficial) aspect of the transverse processes of T2–T9 bilaterally on each human palpatory volunteer. The proctor measured the participant’s palpatory and ultrasound marks against the control markings utilizing a digital caliper and documented the distance in millimeters on the participant’s data sheet (Figure 3). After documenting the data, the proctor cleaned and prepped the prone human subject’s back for the next participant. To analyze the data, the authors utilized IBM SPSS version 23.0 to calculate repeated-measures analysis of variance (ANOVA) on palpation and ultrasound accuracy in landmark location, first utilizing all students, then segmenting students into groups based on patient BMI (utilizing three levels for this independent variable: normal, overweight, obese).

Figure 3:

Measuring ultraviolet markings with ultraviolet light and digital calipers.

Results

A test of the overall hypothesis that participants will show improved accuracy utilizing ultrasound compared with hand palpation was not significant (F=0.8, p>0.05). When separating students into groups according to patient BMI, however, there was a trend toward significance (F=2.9, p=0.071) for an interaction effect between patient BMI and the repeated-measures variable of palpation/ultrasound. When looking specifically at only those participants working with a normal BMI patient, there was a significant improvement in their accuracy with the use of ultrasound (F=7.9, p=0.017) (Table 1).

Discussion

The purpose of this study is to demonstrate if ultrasound may aid novice palpators in their accuracy with regard to palpation of bony landmarks. Palpation of bony landmarks is a foundational skill in osteopathic medical schools. Learning palpation of the thoracic transverse processes is a task that many students initially find difficult. The authors sought with this pilot study to quantify the potential benefits of adding ultrasound to the initial learning of transverse process palpation. Improved accuracy in palpatory skills can directly affect patient outcomes with respect to diagnostic and procedural accuracy. The results found improved accuracy with ultrasound-guided landmark evaluation than palpation alone in a normal BMI volunteer (BMI=18.5–24.99), but not significantly improved when palpating overweight (BMI=25–29.99) or obese (BMI=30+) models. Palpation and imaging of subjects with higher BMIs can be more difficult due to the increased quantity of tissue. In a similar study, identification of the L3 spinous process on a patient model with a BMI of 19.4 yielded significantly more accurate results with ultrasound-assisted palpation [25].

More studies are needed to identify whether there is greater improvement in the accuracy of palpation skills with the increased presence of ultrasound-assisted palpation training. We hope to see this study repeated with a larger population to simulate the larger scale needed to teach ultrasound in medical schools.

Conclusions

The analysis found increased accuracy in bony landmark identification in untrained palpators utilizing ultrasound vs. palpation alone in a normal BMI model, but not in obese or overweight BMI models. This study shows promise to the value that ultrasound may have in medical education, especially with respect to early palpation training and landmark identification.