In-vivo analysis of epicutaneous pressure distribution beneath a femoral tourniquet – an observational study

Abstract

BackgroundCompression of the tissue beneath tourniquets used in limb surgery is associated with varying degrees of soft tissue damage. The interaction between fluids and applied pressure seems to play an important role in the appearance of skin lesions. The extent of the transfer of force between the tourniquet and the skin, however, has yet to be studied. The aim of the present study was to quantify in-vivo the transfer of pressure between a tourniquet and the skin of the thigh.MethodsPressure under the tourniquet was measured using sensors in 25 consecutive patients over the course of elective surgical procedures. Linear mixed modeling was used to assess the homogeneity of the distribution of pressure around the circumference of the limb, variation in pressure values over time, and the influence of limb circumference and the Body-Mass-Index (BMI) on pressure transfer.ResultsMean pressure on the skin was significantly lower than the inner pressure of the cuff (5.95%, 20.5 ± 9.36 mmHg, p < 0.01). There was a discrete, but significant (p < 0.001) increase in pressure within the first twenty minutes after inflation. Sensors located in the area of overlap of the cuff registered significantly higher pressure values (p < 0.01). BMI and leg circumference had no influence on the transfer of pressure to the surface of the skin (p = 0.88 and p = 0.51).ConclusionsPressure transfer around the circumference of the limb was distributed inhomogeneously. The measurement series revealed a global pressure drop compared to the initial pressure of the cuff. No relationship could be demonstrated between the pressure transferred to the skin and the BMI or limb circumference.

Wearable Vector Electrical Bioimpedance System to Assess Knee Joint Health

“…Therefore, the observed knee’s reduced reactance after injury is consistent with anticipated physiological changes as well. The results presented also agree with previous studies existing on assessing knee or lower limb health using bioimpedance [12–14, 23]. …”

“…Applications of the method have included the use of EBI for body composition analysis (i.e., estimation of fat-free mass and total body water) [4, 5], blood volume pulse and limb blood flow quantification [6, 7], cardiac output and function [8, 9], detection of cardiac events such as aortic valve opening [10], wound healing monitoring [11], and, recently, muscle injury and edema assessment [12–14]. To our knowledge, evaluation of EBI as a tool for quantifying knee joint health following acute knee injuries – which may be more subtle as compared to total knee replacement surgery as previously considered [14] – has not been examined by others in the existing literature. Additionally, these previous approaches were mainly limited to controlled lab settings, using bench-top, wall-powered equipment, which are not applicable in a wearable setting.…”

“…In this paper, we present a comprehensive validation of our methods, and unlike previous approaches ([12–14]), we demonstrate engineering contributions which can facilitate translating our technique from the lab to the field or home, including: (1) a larger study on 49 subjects (42 healthy, 7 injured) to validate the performance of the technology in quantifying physiological differences in the knee; (2) a study of the inter-day measurement variability to determine the minimum bioimpedance change that can, with confidence, be attributed to edema as compared to measurement error; (3) a physiological perturbation study aimed at creating small changes in local interstitial fluid volume in the knee based on modulating tissue temperature to quantify the sensitivity of the vector EBI system; (4) an algorithm for automatically detecting periods of high reliability, for gating the data acquisition; and (5) evaluation of a wearable knee wrap-based implementation of our system, with copper band electrodes.…”

Temporary total hip arthroplasty-like spacer for treating an infected periprosthetic femoral fracture using a long stem: A case report

“…Treatment of periprosthetic femoral fracture after revision THA using a long stem was complex and challenging [3]. Furthermore, treatment of infected periprosthetic femoral fractures is even more difficult [1].…”

“…Two-stage reconstruction with the temporary insertion of an antibiotic-loaded cement spacer remains the gold standard for treatment of an infected THA [2]. The treatment of periprosthetic femoral fractures after revision surgery using a long stem is also challenging [3]. Here we report the novel use of a temporary THA-like spacer for treating an infected periprosthetic femoral fracture after revision surgery using a long stem to eradicate infection, stabilize the fracture, and allow partial weight bearing without pain.…”