Non-invasive assessment of muscle compartment elasticity by pressure-related ultrasound in pediatric trauma: a prospective clinical study in 25 cases of forearm shaft fractures.

BACKGROUND: Soft-tissue swelling after limb fractures in pediatric patients is well known to be a risk factor for developing acute compartment syndrome (ACS). Clinical assessment alone is uncertain in specific cases. Recently, we proposed a non-invasive ultrasound-based method to objectify muscle compartment elasticity for monitoring. We hypothesize a strong correlation between the soft-tissue swelling after stabilization of upper limb fractures and the compartment elasticity objectified with a novel ultrasound-based approach in pediatric trauma. PATIENTS AND METHODS: In a prospective clinical study, children suffering forearm fractures but not developing an ACS were included. The muscle compartment elasticity of the m. flexor carpi ulnaris was assessed after surgical intervention by a non-invasive, ultrasound-based method resulting in a relative elasticity (RE in %) in both the control (healthy limb) and study group (fractured limb). Soft-tissue swelling was categorized in four different levels (0-3) and correlated with the resulting RE (%). RESULTS: The RE in the study group (15.67%, SD ± 3.06) showed a significantly decreased level (p < 0.001) compared with the control (22.77%, SD ± 5.4). The categorized grade of soft-tissue swelling resulted in a moderate correlation with the RE (rs = 0.474). CONCLUSIONS: The presented study appears to represent a novel approach to assess the posttraumatic pressure changes in a muscle compartment after fracture stabilization non-invasively. In this first clinical study in pediatric cases, our measurement method represents a low-cost, easy, and secure approach that has the potential to substitute invasive measurement of suspected ACS in muscle compartment conditions. Further investigations in lager cohorts are required to prove its daily clinical practicability and to confirm the expected reliability.

Non-invasive and reliable assessment of compartment elasticity by pressure related ultrasound: An in-vitro study.

PURPOSE: The development of acute compartment syndrome is a serious threat to trauma patients. The clinical assessment alone is not reliable enough to determine the need for fasciotomy in many cases. The Physician´s assessment of the elasticity of the muscle compartment might be particularly important to objectively evaluate the pressure in this enclosed space. The purpose of this study was to determine the observer´s reproducibility, of compartment elasticity measurements by a novel ultrasonic approach. METHODS: Increasing intra-compartmental pressures (ICP) were simulated in a water filled in-vitro model. Pressure related ultrasound was used to determine the relative elasticity (RE) of soft tissue compartments. A pressure transducing probe head was combined with the ultrasonic probe to obtain cross section views of the simulated compartment and to detect the amount of applied pressure by the observer. In this model, the compartment depth without compression (P0) was set to be 100%. Changes of the compartment depth due to a probe pressure of 80 mmHg (P80) were correlated to P0 and an elasticity quotient as a value for RE (%) was calculated. Twelve blinded observers performed measurements for RE determination (%) under three pressure conditions. Reproducibility was calculated using intraclass correlation coefficient (ICC). RESULTS: Measurements (n = 432) revealed that the RE (%) in the control group was 17,06% (SD+/-2,13), whereas the RE of the group ICP30 significantly decreased to 12,66% (SD+/- 1,19) (p<0,001). The ICP50 group revealed a further significant decrease to 8,43% (SD+/- 0,67) (p<0,001). Repeated measurement of RE and ICP showed a high level of correlation (spearman correlation coefficient: roh=0,922). A RE <14% resulted in a sensitivity of 96% and a specificity of 90,3% for diagnosis of an ICP >30 mmHg. ICCinter was 0,986; 95%, CI: 0,977-0,992 (p<0,001). DISCUSSION: The presented ultrasound-based approach reliably assesses the elasticity in a simulated compartment model. In this pioneer study investigating the inter- and intra-observer reproducibility, this method of measurement appears to be of low cost in addition to being an easy and secure approach that may have the potential to substitute invasive measurement. Further investigations are required to improve its feasibility and to confirm the reliability under clinical conditions.

Assessment of elevated compartment pressures by pressure-related ultrasound: a cadaveric model.

PURPOSE: There is a risk of misinterpreting the clinical signs of acute compartment syndrome of the lower limb resulting in delayed fasciotomy. Up to date, the diagnosis of compartment syndrome is based on clinical assessment and of invasive needle pressure measurement in uncertain cases. Close monitoring is necessary for early recognition of raising compartment pressures. Clinical assessment of muscle firmness by the physician's palpation alone is unreliable. Thus, a device objectifying this assessment would be beneficial. The purpose of this study was to determine the feasibility of muscle compartment elasticity measurements by a novel and non-invasive device using pressure-related ultrasound. METHODS: In a cadaveric model, the anterior tibial compartment was prepared to simulate raising intra-compartmental pressures (0-80 mmHg) by saline infusion. Standard invasive pressure monitoring was compared with a novel method to determine tissue elasticity. Changing cross-sectional view in B-mode ultrasound was exerted to measure the compartment depth before and after physician's probe compression of 100 mmHg. Compartment displacement (∆d) was measured and related to the corresponding compartmental pressure (Spearman correlation coefficient). Delta (mm) of the control group at 10 mmHg compartment pressure was compared with measured data at rising compartmental pressures of 30, 50, and 70 mmHg using the Wilcoxon rank-sum test. The intra-observer reliability (κ) was additionally calculated. RESULTS: Fresh and never frozen lower human limbs (n = 6) were used. The average displacement measured in the anterior tibial compartment was 2.7 mm (0.3-6.7 mm). A concordant consistent correlation between the compartmental displacement and the intra-compartmental pressure occurred. The Spearman coefficient (r s = 0.979) showed a significant correlation between the rising pressure and the decreasing tissue displacement visualized by ultrasound. The intra-observer value kappa showed reliable values (κ 10 = 0.73, κ 30 = 0.80, and κ 70 = 0.79). CONCLUSIONS: We introduce a new method of ultrasound imaging enhanced with probe pressure measurement to determine changes of the visco-elastic behavior of isolated muscle compartments. Pressure-related ultrasound could be a reliable tool to determine the correlation between the measured compartmental displacement and the increasing intra-compartmental pressure. Its accuracy revealed promising results. This technique may help the physician to objectify the clinical assessment of compartment elasticity, mainly indicated in cases of unconscious patients and imminent pathology. Further clinical studies and improvements of this technique are required to prove its accuracy and reliability in cases of compartment syndrome.

[An optimised assessment of "severely injured patients" for the documentation of road traffic accident black spots]. / Eine optimierte Bewertung "Schwerverletzter" zur Dokumentation von Unfallschwerpunkten im Straßenverkehr.

INTRODUCTION: The success of traffic safety improvement strategies is based on documentation. Analysis and remedy of accident black spots in addition to improvements in automobile production involve the work of traffic engineers, politicians, traffic regulations, police, and medical care. To create priorities, the traffic statistics differentiate accidents in a 3-class system in relation to severe accidents: slightly injured, severely injured and fatally injured (death). This study assesses the validity of the existing classification of "severely injured" compared with the actual injury severity. MATERIAL AND METHOD: We analysed accidents resulting in 182 "severely injured" people in one year in a city model. A synchronisation of anonymous police documentation with the medical notes of admitted casualties which were validated by established trauma scores and medical classification was undertaken. A correlation analysis of length of stay should give indications of the actual injury severity. RESULTS: The study group showed a ubiquitous range of age, sex and injuries despite a relatively low case number. The range of MAIS, ISS and NACA index scores shows the inhomogeneity of the people classified as "severely injured". 70 % of the study group revealed ISS < 16 which means that they are not polytraumatised patients. The correlation analysis according to Spearman certifies the validity of these scores (r MAIS/NACA = 0.645 and r ISS/NACA = 0.592). The further differentiation on the basis of MAIS, ISS and NACA showed that 51 % of the study group should be classified as slightly injured and 83 % of these were discharged in less than 5 days. CONCLUSION: This study shows that the traffic safety classification of "severely injured" people is not sufficient and most severely injured people are not even approximately recorded. We propose that a new continuous link system between police and medical data will be inevitable for future improvements in traffic safety. The use of established trauma scores and a differentiated look at lengths of stay could be an option.