Bio-electrical impedance analysis for perioperative fluid evaluation in open major abdominal surgery

Association Between Changes in Bioelectrical Impedance Analysis (BIA) Parameter and the Clinical Outcomes in Patients With Acute Heart Failure

BACKGROUND

Volume overload is associated not only with clinical manifestations but also with poor outcomes of heart failure (HF). However, there is an unmet need for effective methods for serial monitoring of volume status during HF hospitalization. The aim of this study was to evaluate the prognostic implication of serial measurement of bioelectrical impedance analysis (BIA) in patients hospitalized with acute HF.

METHODS

This study is a retrospective observational study and screened 310 patients hospitalized due to acute decompensated HF between November 2021 and September 2022. Among them, 116 patients with acute HF who underwent BIA at the time of admission and at discharge were evaluated. We investigated the correlation between change of BIA parameters and the primary composite outcome (in-hospital mortality or rehospitalization for worsening HF within one month).

RESULTS

The median (interquartile range) age was 77 years (67-82 years). The mean left ventricular ejection fraction was 40.7 ± 14.6% and 55.8% of HF patients have HF with reduced ejection fraction. The body water composition (intracellular water [ICW], extracellular water [ECW], and total body water [TBW]) showed a statistically significant correlation with body mass index and LV chamber sizes. Furthermore, the ratio of ECW to TBW (ECW/TBW), as an edema index showed a significant correlation with natriuretic peptide levels. Notably, the change of the edema index during hospitalization (ΔECW/TBW) showed a significant correlation with the primary outcome. The area under the curve of ΔECW/TBW for predicting primary outcome was 0.71 (95% confidence interval [CI], 0.61-0.79; P = 0.006). When patients were divided into two groups based on the median value of ΔECW/TBW, the group of high and positive ΔECW/TBW (+0.3% to +5.1%) had a significantly higher risk of the primary outcome (23.2% vs. 8.3%, adjusted odds ratio, 4.8; 95% CI, 1.2-19.3; P = 0.029) than those with a low and negative ΔECW/TBW (-5.3% to +0.2%).

CONCLUSION

BIA is a noninvasive and effective method to evaluate the volume status during the hospitalization of HF patients. The high and positive value of ΔECW/TBW during hospitalization was associated with poor outcomes in patients with HF.

Detecting and Monitoring Periprosthetic Joint Infection by Using Electrical Bioimpedance Spectroscopy: A Preliminary Case Study

A method to detect the presence of infection after Total Joint Arthroplasty is presented. The method is based on Electrical Bioimpedance Spectroscopy and guarantees low latency, non-invasiveness, and cheapness with respect to the state of art. Experimental measurements were carried out on a singular patient who had already undergone bilateral Total Knee Arthroplasty. He was affected by a hematogenous Periprosthetic Joint Infections on the left knee. The right knee was adopted as the reference. Measurements were acquired once before the surgical procedure (Diagnosis Phase) and twice in the postoperative phases (Monitoring Phase). The most relevant frequency range, for diagnosis and monitoring phases, was found to be between 10 kHz to 50 kHz. The healing trend predicted by the decrease of impedance magnitude spectrum was reflected in clinical and laboratory results. In addition, one month after the last acquisition (two months after the surgery), the patient fully recovered, confirming the prediction of the Electrical Bioimpedance Spectroscopy technique.

Bioimpedance Sensor and Methodology for Acute Pain Monitoring

The paper aims to revive the interest in bioimpedance analysis for pain studies in communicating and non-communicating (anesthetized) individuals for monitoring purpose. The plea for exploitation of full potential offered by the complex (bio)impedance measurement is emphasized through theoretical and experimental analysis. A non-invasive, low-cost reliable sensor to measure skin impedance is designed with off-the-shelf components. This is a second generation prototype for pain detection, quantification, and modeling, with the objective to be used in fully anesthetized patients undergoing surgery. The 2D and 3D time-frequency, multi-frequency evaluation of impedance data is based on broadly available signal processing tools. Furthermore, fractional-order impedance models are implied to provide an indication of change in tissue dynamics correlated with absence/presence of nociceptor stimulation. The unique features of the proposed sensor enhancements are described and illustrated here based on mechanical and thermal tests and further reinforced with previous studies from our first generation prototype.