Keser F. et al., 2023: The effect of bioelectric impedance analysis on the success of extracorporeal shock wave lithotripsy

Thursday, 15 February 2024

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Keser F, Culpan M, Cakici MC, Atis RG, Yildirim A.
Department of Urology, Faculty of Medicine, Istanbul Medeniyet University, Istanbul, Turkey.
Department of Urology, Faculty of Medicine, Istanbul Medeniyet University, Istanbul, Turkey.
Department of Urology, Istanbul Goztepe Prof. Dr. Suleyman Yalcin City Hospital, Istanbul, Turkey.
Department of Urology, Sisli Memorial Hospital, Istanbul, Turkey.

Abstract

Bioelectric impedance analysis (BIA) is a non-invasive method that can show the distribution of fatty and lean mass of the body. In this study, we aimed to determine the effect of BIA on extracorporeal shock wave lithotripsy (SWL) success. Our secondary aim was to determine the factors predicting transition from a single SWL session to multiple sessions. Patients who underwent SWL due to kidney stones were prospectively included. Demographics, pre-procedural BIA parameters (fat percentage, obesity degree, muscle mass, total water and metabolic rate), stone parameters, and number of SWL sessions were recorded. Univariate and multivariate regression analyzes were made to determine independent risk factors for success. Then, the successful group was divided into two subgroups according to their SWL session number as one session or multiple sessions and multivariate regression analysis was made to determine independent risk factors. Stone-free status was achieved in 114 (61.2%) of 186 patients. Stone Hounsfield Unit (HU) (OR: 0.998, p = 0.004), stone volume (OR: 0.999, p = 0.023) and fat percentage (OR: 0.933, p = 0.001) were independent risk factors for stone-free status in multivariate analysis. HU value of the stone (OR: 1.003, p = 0.005) and age (OR: 1.032, p = 0.031) were determined as independent risk factors for transition to multiple sessions in the subgroup analysis of the successful group. Fat percentage, stone volume, and stone density were determined as factors affecting success in SWL. Routine use of BIA may be considered to predict success before SWL. The probability of SWL success in a single session decreases as the age and stone's HU value increase.

Urolithiasis. 2023 Jul 4;51(1):93. doi: 10.1007/s00240-023-01465-z.PMID: 37400587

Comments 1

Hans-Göran Tiselius on Thursday, 15 February 2024 10:00

Predicting the outcome of SWL has become increasingly difficult the more variables that are considered. In the current report some variables, not commonly included in such analyses, were found to be of importance for successful outcome following one or multiple sessions.
The following factors were considered important:

BMI
Fat%
Muscle-free mass
Waist circumference
Skin-Stone distance (SSD)
Stone density, HU
Stone diameter and stone volume
HU of stone/skin tissue

All treatments in this report were based on treatments with the Lithostar Modularis Lithotripter and with only 75 mg of diclofenac administered intramuscularly. This is a rather mild form of analgesia and when the authors also state that the energy level was chosen to the patient’s tolerance, some doubts can be raised regarding the treatment ambition.

The mean number of sessions in the successful and unsuccessful groups were 1.73 and 2.28. The number in successfully treated patients was higher than expected.

Interestingly the authors present a formula comprising stone volume, fat ratio and HU. It is, however, not directly obvious how, in this article, the constant and factor B were obtained.
Although the authors conclude that stone volume, stone density (HU) and fat percentage were the important determinants for SWL success, it is unlikely that analysis of fat% will become part of the primary clinical evaluation before choosing method for stone removal!

Not indicated in the report is how the operators were educated, how their skill and experience affected stone disintegration and to which extent variations in levels of ambition might have affected the outcome.

From a theoretical point of view the results show the well-recognized feature that transmission of shockwaves are favored by a high water content in the tissues and counteracted by the fatty zone.

The reviewer is surprised that SSD still is expressed as the mean of distances at 0o, 45o and 90o, when this distance easily and more exact can be measured along the transmission line of the shock wave.

Hans-Göran Tiselius

BMI
Fat%
Muscle-free mass
Waist circumference
Skin-Stone distance (SSD)
Stone density, HU
Stone diameter and stone volume
HU of stone/skin tissue

All treatments in this report were based on treatments with the Lithostar Modularis Lithotripter and with only 75 mg of diclofenac administered intramuscularly. This is a rather mild form of analgesia and when the authors also state that the energy level was chosen to the patient’s tolerance, some doubts can be raised regarding the treatment ambition.

The mean number of sessions in the successful and unsuccessful groups were 1.73 and 2.28. The number in successfully treated patients was higher than expected.

Interestingly the authors present a formula comprising stone volume, fat ratio and HU. It is, however, not directly obvious how, in this article, the constant and factor B were obtained.
Although the authors conclude that stone volume, stone density (HU) and fat percentage were the important determinants for SWL success, it is unlikely that analysis of fat% will become part of the primary clinical evaluation before choosing method for stone removal!

Not indicated in the report is how the operators were educated, how their skill and experience affected stone disintegration and to which extent variations in levels of ambition might have affected the outcome.

From a theoretical point of view the results show the well-recognized feature that transmission of shockwaves are favored by a high water content in the tissues and counteracted by the fatty zone.

The reviewer is surprised that SSD still is expressed as the mean of distances at 0o, 45o and 90o, when this distance easily and more exact can be measured along the transmission line of the shock wave.

Hans-Göran Tiselius

Predicting the outcome of SWL has become increasingly difficult the more variables that are considered. In the current report some variables, not commonly included in such analyses, were found to be of importance for successful outcome following one or multiple sessions. The following factors were considered important: BMI Fat% Muscle-free mass Waist circumference Skin-Stone distance (SSD) Stone density, HU Stone diameter and stone volume HU of stone/skin tissue All treatments in this report were based on treatments with the Lithostar Modularis Lithotripter and with only 75 mg of diclofenac administered intramuscularly. This is a rather mild form of analgesia and when the authors also state that the energy level was chosen to the patient’s tolerance, some doubts can be raised regarding the treatment ambition. The mean number of sessions in the successful and unsuccessful groups were 1.73 and 2.28. The number in successfully treated patients was higher than expected. Interestingly the authors present a formula comprising stone volume, fat ratio and HU. It is, however, not directly obvious how, in this article, the constant and factor B were obtained. Although the authors conclude that stone volume, stone density (HU) and fat percentage were the important determinants for SWL success, it is unlikely that analysis of fat% will become part of the primary clinical evaluation before choosing method for stone removal! Not indicated in the report is how the operators were educated, how their skill and experience affected stone disintegration and to which extent variations in levels of ambition might have affected the outcome. From a theoretical point of view the results show the well-recognized feature that transmission of shockwaves are favored by a high water content in the tissues and counteracted by the fatty zone. The reviewer is surprised that SSD still is expressed as the mean of distances at 0o, 45o and 90o, when this distance easily and more exact can be measured along the transmission line of the shock wave. Hans-Göran Tiselius

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