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Upper thoracic percussion is a fundamental technique in clin- Purpose The demand for telemedicine is continuously in- ical examinations, difficult to learn and highly subjective, creasing. However, many medical examination techniques but widely used for the initial diagnosis of lung diseases such as auscultation are based on manual execution and (e.g. Pneumothorax, Pleural Effusion). Therefore, ausculta- subjective assessment by each individual doctor. For the in- tory percussion is used by tapping the patient on the sternum creasing trend of telemedicine, we have developed an elec- while listening to the posterior thorax with a stethoscope.[1–4] tric percussion device that examines in a standardized way. A key clinical finding from percussion is that the pneumotho- Methods This study evaluated the new approach of us- rax sounds hyper-sonorous and pleural effusion is dulled. ing motorized percussion against the gold standard of To distinguish between empty and filled body cavities – manual percussion. An examination was carried out on a sonorous and tympanic sounds – the percussion was intro- healthy volunteer using both techniques. Thereby, occur- duced to medicine by Leopold Auenbrugger in 1763. He began ring sounds from both pulmonary and non-pulmonary areas tapping the patient’s body surface in the affected region to pro- were recorded as the primary goal of percussion is to as- duce sounds of resonance. sess the size of the lung. Recordings were cut into individual Physical examination, the other major established diagnos- samples and randomized within each examination variant. tic method, suffers from several disadvantages, most no- Results When discriminating between ventral and dorsal, tably low accuracy and high interobserver error. The ac- and manual and motorized percussion, the outcome of the cumulation of fluid in the lungs (consolidation), char- 28-participant anonymous survey showed that the noise- acteristic of pneumonia, cannot be reliably detected. suppressed ventral motorized percussion with 93.2% (10.2) Today, increasingly more techonological devices (e.g. wear- correctly identified percussion points surpassed all other con- ables) are being developed for telemedicine and home care ducted percussion techniques. systems. However, percussion as a simple inexpensive and fast Conclusion Making a distinction between pulmonary vol- diagnostic method is still left out, as the examination cannot be ume and exterior areas is very reliable with the motorized performed by a layperson. percussion. In order to be able to describe the clinical pic- ture precisely in the future, further evaluations are necessary. 2 Methods Keywords: Percussion · Auscultation · Telemedicine · Tele- diagnostics · Clinical Examination 2.1 Motorized Percussion Setup To overcome the challenges of a manual percussion, we de- veloped a device for an automatic percussion. As described *Corresponding author: Annika Hangleiter, Research Group in , three working principles were evaluated in a previous MITI - Minimally Invasive Interdisciplinary Therapeutical comparative study, resulting in the motorized approach being Intervention, Klinikum rechts der Isar, Technical University Munich, the most favorable. We therefore improved the first prototype Munich, Germany„ e-mail: firstname.lastname@example.org of the mechanical approach, resulting in the new overall di- Maximilian Berlet, Jonas Fuchtmann, Roman Krumpholz, Hubertus Feußner, Dirk Wilhelm, Research Group MITI - mensions of 230 mm x 170 mm x 160 mm (Fig. 1). Core of Minimally Invasive Interdisciplinary Therapeutical Intervention, the system is a HSR-2645 CR continuous drive servo mo- Klinikum rechts der Isar, Technical University Munich, Munich, tor (HITEC, Sand Diego, USA), placed on a conventional Germany manufactured aluminum plate. All further parts are designed Maximilian Berlet, Hubertus Feußner, Dirk Wilhelm, Depart- for additive manufacturing and were printed with a Form 3B ment of Surgery, Klinikum rechts der Isar, Technical University Munich, Munich, Germany (Formlabs, Somerville, USA). A transmission rotor with three Open Access. © 2022 The Author(s), published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. 38 A. Hangleiter et al., Motorized Percussion strokes causes a continuous prestress on a torsion spring with ventral percussion (V) – where the sternum was targeted – each stroke in form of a short interlock power transmission. with a dorsal auscultation, and a dorsal percussion (D) with a This causes an intermittent knocking on an aluminum plate dorsal auscultation; both performed with the motorized device plessimeter. and manual tapping. Fig. 1: a) CAD-Model of the motorized percussion applicator with an inside view; b) Prototype with adapted stethoscope Fig. 3: Considered points for percussion and auscultation on the ventral (left) and dorsal (right) patient side; Auscultation was al- The entire device is designed to be handheld and therefore ways carried out dorsal (D) includes a stethoscope mounting option using a custom stetho- scope mount in conjunction with a silicone spacer to isolate vibrations. 2.3 Sound pattern editing Volumes of recordings were normalized and each examina- 2.2 Experimental setup tion was split into 12 individual samples corresponding to the anatomical points as shown in Figure 3. While recordings For capturing produced percussion sounds in this evaluation, a of the manual percussion sounds were not further processed, TM TM ® Master Classic II stethoscope (3M Littmann , St. Pauls, sounds of the automatized percussion were filtered addition- USA) picked up the sound directly from the patient’s skin. Au- ally. Since the sound of the motor is mixing up with the biosig- dio signals were digitized by a microphone and converted into nals, a noise reduction (NR) filter based on the technique of 24-bit/192 kHz recordings using a UR824 interface (Stein- spectral noise gating (parameters: 42 dB noise reduction, 12.5 berg Media Technologies GmbH, Hamburg, Germany). The sensitivity, 12 tapes of frequency smoothing) was applied us- experiment was performed on one healthy testperson, sitting ing the software Audacity (version 3.0.0) to clear up the tap- upright. To compare multiple variants and verify with the gold ping sound. When an unwanted sound region is selected, Au- standard of a manual percussion, 6 spots within and 6 spots dacity identifies a profile. Then, by selecting the entire region outside of the pulmonary area, corresponding to the points in of the waveform to which noise reduction is to be applied, the Fig. 3, were defined. The four tested variants differ between unwanted noise is reduced using the previously created pro- Fig. 2: Comparison of the spectral audio tracks of three different motorized examinations. Top to bottom: MOT-PD/AD; MOT-PD/AD-NR; MOT-PV/AD-NR; Especially noticeable, ventral percussion shows no yellow spectral colors outside the lung border (pt. 7 - 12); Inopera- ble point 11: MOT-PV/AD-NR with adverse interfering noise – a negative example 39 A. Hangleiter et al., Motorized Percussion file. Figure 2 shows a section of the processed audio tracks. interquartile ranges (IQR). Statistical methods conform with Differences in noise reduction are shown in blue. Friedman and Wilcoxon Ranksum tests within a Bonferroni correction, using the statistical software R (version 4.2.0). 2.4 Survey Design For the survey, v fi e individual examination versions were com- pared: i manual ventral percussion with dorsal auscultation (MAN PV/AD) ii manual dorsal percussion with dorsal auscultation (MAN PD/AD) iii motorized dorsal percussion with dorsal auscultation (MOT PD/AD) iv motorized ventral percussion with dorsal auscultation and noise reduction (MOT PV/AD NR) v motorized dorsal percussion with dorsal auscultation and noise reduction (MOT PD/AD NR) Evaluators had to listening v fi e sound tracks of each exam- ination and identify which were samples of within the lung area. For this purpose, using Kdenlive (version 21.12.3), short videos of the audio recordings combined with images for each numbered point were edited. Participants were informed about Fig. 4: Comparison between manual (MAN) and motorized (MOT) the 50:50 split of lung and non-lung samples and were able to percussion (P); Distinguished between percussion from ventral (V) and dorsal (D); Further noise reduction is indicated as (NR); Aus- listen to two reference samples for each examination. In all cultation (A) in all cases from dorsal (D); Statistical significance: videos the audio track was played to the listener with random- *** = p < 0.001 ized percussion points, deviating from the order in figure 3. Finally, the respondents answered questions about the possi- The audio example with the motor noise (MOT PD/AD: ble use of an AI in combination with the motorized percussion 50.0% (25.0)) was less assignable than the other two audio mechanism. The survey was aimed to approbated physicians examples (MOT PV/AD NR: 93.2% (10.2); MOT PD/AD and medical students, who are already familiar with the use of NR: 66.7% (12.5)) of motorized percussion with noise fil- percussion, and in addition also at laypersons, who have not tering. Although, ventral manual percussion (MAN PV/AD: yet had contact with everyday medical practice. 87.5% (18,8)) was the quietest it achieved a better result than dorsal manual percussion (MAN PD/AD: 62.5% (50.2)). No statistically significant differences were found between the age groups. Gender differences are up to 16.7 %, with women per- 3 Results forming better than men. Additionally, 79% of all participants agree and 21% are unsure if artificial intelligence will be able In total, 28 participants (9 approbated physicians / 6 medical to categorize these sounds in the future (79% / 21% / 0%). students / 13 laypersons – average age: Mdn = 28.5 yrs (8.5)) show a significant superiority of the ventral (V) percussion. Even though results for the manual ventral and motorized ven- tral percussion can be compared to one another, results for 4 Discussion motorized sounds (MOT PV/AD NR: 93.2% (10.2)) are even slightly better than those for manual tapping (MAN PV/AD: Percussion and auscultation, are fundamental diagnostic tech- 87.5% (18,8)). In general, ventral percussion and dorsal aus- niques in medical examinations, thus it is surprising that no cultation sounds were quieter than the rest, which is why automatic system for general use is yet available. While re- participants were not shown the ventral audio sample of the sults of our system are quite promising, one has to consider for device without previous noise reduction. All results, includ- the evaluation, that usually the current percussion and auscul- ing Table 1 are provided as median (Mdn) values (%) and tation spot is visible for the physician. Hence, their anatom- 40 A. Hangleiter et al., Motorized Percussion ical knowledge adds additional information to the pure au- cal approval: The research related to human use complies with dio feedback. In our setup, timbre was difficult to distinguish all the relevant national regulations, institutional policies and when both percussion and auscultation were performed from was performed in accordance with the tenets of the Helsinki dorsal. Percussion, during both procedures manual and motor- Declaration, and has been approved by the authors’ institu- ized, was more distinguishable when performed from ventral. tional review board or equivalent committee. However, with a ventral percussion, the increasing distance, between the tapping point and the caudally guiding stetho- Acknowledgement I would like to thank all participants scope, automatically leads to a softer and also brighter sound. for listening attentively and for the interesting questions. A more compact design and damping of the engine noise are further steps to improve the overall concept. Whether as a multi-functional device in telemedicine, as a tool for practi- References tioners or as an independent self-care application in combi-  Winter R et al. (1999) Percussion - a new way to diag- nation with a robotic arm, the motorized device produces a nose a pneumothorax, British Journal of Anaesthesia, periodic, reliable sound with a constant impact force. 10.1093/bja/83.6.960  Harris A (2015) Listening-touch, Affect and the Crafting of Medical Bodies through Percussion, Body & Society, 10.1177/1357034X15604031 5 Conclusion  Byermoen K et al.(2021) Reflection on actions: Identify- ing facilitators of and barriers to using physical assess- We were able to proof that a motorized percussion can keep ment in clinical practice, Nurse Education in Practice, 10.1016/j.nepr.2020.102913 up with manual percussion and could bring the traditional  Wipf J et al. (1999) Diagnosing Pneumonia by Physical examination technique to the 21st century. Digitization and Examination Relevant or Relic?, JAMA Internal Medicine, standardization open up new possibilities for future Artificial 10.1001/archinte.159.10.1082 Intelligence-based classification of the percussion and could  Pschyrembel W (2014) Klinisches Wörterbuch (266. A.), lead to substantially more objective decisions without the need Boston, de Gruyter, 3110339978 for an experienced doctor. Most medical professionals agreed  Auenbrugger L (1761) Inventum novum, ex percus-sione thoracis hmani ut signo abstrusos interni pectoris morbos that recordings with a microphone sound different than classic deteendi, vol 1. J.T, Trattner, Vienne, p525 percussions, but the work further shows that the natural timbre  Riishede M et al. (2021) Point-of-care ultrasound of the does not play an important role in the categorization of the heart and lungs in patients with respiratory failure: a prag- audio recordings. Our developed percussion applicator is low matic randomized controlled multicenter trial, Scandinavian cost build, simple to handle and offers a rapid and inexpensive Journal of Trauma, Resuscitation and Emergency Medicine 10.1186/s13049-021-00872-8 examination for e.g. pneumothorax/pleural effusions.  Krumpholz R et al. (2021) Telemedical percussion: objec- tifying a fundamental clinical examination technique for Author Statement Research funding: The author state telemedicine, International Journal of Computer Assisted no funding involved. Conflict of interest: Authors state no Radiology and Surgery, 10.1007/s11548-021-02520-z conflict of interest. Informed consent: Informed consent has  Guarino J (1980) Auscultatory Percussion of the chest, The been obtained from all individuals included in this study. Ethi- Lancet, 10.1016/S0140-6736(80)91788-2 Tab. 1: Correct answers sorted by sex and by medical expertise; Noteworthily, laypersons achieved comparable results to those with a medical background; All groups were able to assign the ventral motorized percussion with noise reduction (MOT PV/AD NR) best; Results in median values (%) and interquartile ranges (IQR); Abbreviations according to Fig. 4 MAN MOT PVAD PDAD PDAD PVAD NR PDAD NR % IQR % IQR % IQR % IQR % IQR Women (n=17) 91,7 25,0 66,7 25,0 50,0 25,0 95,5 13,6 66,7 12,5 Men (n=11) 83,3 12,5 50,0 54,2 58,3 20,8 90,9 9,1 62,5 4,2 Physicians (n=9) 83,3 16,7 58,3 50,0 66,7 8,3 86,4 9,1 62,5 4,2 Medical Students (n=6) 91,7 6,3 37,5 31,3 41,7 6,2 86,4 20,5 66,7 15,6 Laypersons (n=13) 83,3 25,0 66,7 25,0 50,0 25,0 95,5 0,0 66,7 12,5 Total (n=28) 87,5 18,8 62,5 52,1 50,0 25,0 93,2 10,2 66,7 12,5
Current Directions in Biomedical Engineering – de Gruyter
Published: Jul 1, 2022
Keywords: Percussion · Auscultation · Telemedicine · Telediagnostics · Clinical Examination
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