title: Assessment of elevated compartment pressures by pressure-related ultrasound: a cadaveric model.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Orthopaedic Trauma, Sana Klinikum Offenbach, Starkenburgring 66, 63069, Offenbach, Germany. richard.sellei@sana.de.
authors.forename: R M
authors.initials: RM
authors.lastname: Sellei
authors.affiliation: Department of Orthopaedic Trauma, Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hingmann
authors.affiliation: Department of Orthopaedic Trauma, Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Weber
authors.affiliation: Helmholtz-Institute for Biomedical Engineering, Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Jeromin
authors.affiliation: Helmholtz-Institute for Biomedical Engineering, Chair of Medical Engineering, RWTH Aachen University, Aachen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Zimmermann
authors.affiliation: Department of Orthopaedics and Trauma, Queen Alexandra Hospital, Portsmouth, UK.
authors.forename: J
authors.initials: J
authors.lastname: Turner
authors.affiliation: Department of Orthopaedic Trauma, Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Hildebrand
authors.affiliation: Department of Orthopaedic Trauma, Aachen University, Pauwelsstr. 30, 52074, Aachen, Germany.
authors.forename: H-C
authors.initials: HC
authors.lastname: Pape
mesh_terms: D002102:Cadaver; D016022:Case-Control Studies; D003161:Compartment Syndromes / Q000000981:diagnostic imaging*; D042241:Early Diagnosis; D004548:Elasticity / Q000502:physiology; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology; D011312:Pressure; D012965:Sodium Chloride / Q000008:administration & dosage; D013977:Tibia; D014463:Ultrasonography / Q000295:instrumentation
chemical_list: D012965:Sodium Chloride
keywords: Imminent compartment syndrome; Intra-compartmental pressure; Muscle elasticity; Non-invasive device; Pressure-related ultrasound