Joe Guarino

Auscultatory percussion: a simple method to detect pleural effusion

AbstractObjective: To assess a new technique for the detection of free pleural fluid. Design: 118 consecutive inpatients with radiologic evidence of free pleural fluid and a control group of 175 randomly selected inpatients were examined over a three-year period in a prospective blind study by auscultatory percussion (AP) for evidence of pleural effusion. The cutoff in the percussion note by AP is strikingly loud and sharp at the fluid level and allows precise delineation of even minimal amounts of pleural fluid. The fluid level was measured in reference to the last rib. The criterion for detection of pleural effusion by AP was a demonstrable horizontal fluid level at the sound cutoff across the posterior hemithorax above the last rib that shifted with lateral tilt. Setting: A general medical and surgical university-affiliated teaching Veterans Affairs hospital. Patients/participants: All inpatients were eligible. Ready availability of examiners was essential. Rotating third- and fourth-year medical students, residents, and senior staff members participated. Interventions: None. Major results: 113 of the 118 patients with radiologic evidence of pleural effusion had a distinct horizontal fluid level above the last rib that shifted with lateral tilt (sensitivity = 95.8% ). None of the 175 control patients examined at random showed evidence of pleural effusion by AP examination, which was confirmed by chest radiography (specificity = 100%). Nine of the 175 patients without radiologic evidence of pleural effusion had elevated diaphragms that simulated a fluid level in the examination by AP. Each of the nine patients, however, had no shift in the level with lateral tilt. Subpulmonic effusions were readily displaced and identified by this method of AP. Conclusions: Examination by AP is highly sensitive and specific for the detection of free pleural fluid, even in the presence of obesity, thickened pleura, lung masses, pneumonia, and associated lung disease. The examination correlates closely with standard and lateral decubitus chest radiography. Pleural effusion unsuspected by conventional means of physical examination and undetectable by standard chest radiography can readily be detected by the method of AP. The examination is easy to do and is particularly suited to enhance detection of pleural effusion. As little as 50 mL of free pleural fluid can be detected.OBJECTIVE To assess a new technique for the detection of free pleural fluid. DESIGN 118 consecutive inpatients with radiologic evidence of free pleural fluid and a control group of 175 randomly selected inpatients were examined over a three-year period in a prospective blind study by auscultatory percussion (AP) for evidence of pleural effusion. The cutoff in the percussion note by AP is strikingly loud and sharp at the fluid level and allows precise delineation of even minimal amounts of pleural fluid. The fluid level was measured in reference to the last rib. The criterion for detection of pleural effusion by AP was a demonstrable horizontal fluid level at the sound cutoff across the posterior hemithorax above the last rib that shifted with lateral tilt. SETTING A general medical and surgical university-affiliated teaching Veterans Affairs hospital. PATIENTS/PARTICIPANTS All inpatients were eligible. Ready availability of examiners was essential. Rotating third- and fourth-year medical students, residents, and senior staff members participated. INTERVENTIONS None. MAJOR RESULTS 113 of the 118 patients with radiologic evidence of pleural effusion had a distinct horizontal fluid level above the last rib that shifted with lateral tilt (sensitivity = 95.8%). None of the 175 control patients examined at random showed evidence of pleural effusion by AP examination, which was confirmed by chest radiography (specificity = 100%). Nine of the 175 patients without radiologic evidence of pleural effusion had elevated diaphragms that simulated a fluid level in the examination by AP. Each of the nine patients, however, had no shift in the level with lateral tilt. Subpulmonic effusions were readily displaced and identified by this method of AP. CONCLUSIONS Examination by AP is highly sensitive and specific for the detection of free pleural fluid, even in the presence of obesity, thickened pleura, lung masses, pneumonia, and associated lung disease. The examination correlates closely with standard and lateral decubitus chest radiography. Pleural effusion unsuspected by conventional means of physical examination and undetectable by standard chest radiography can readily be detected by the method of AP. The examination is easy to do and is particularly suited to enhance detection of pleural effusion. As little as 50 mL of free pleural fluid can be detected.

Modal analysis of a fluid-filled elastic shell containing an elastic sphere

Abstract Auscultatory percussion (AP) is an examination used to detect brain disease. The physical mechanisms involved in AP are investigated by determining the natural frequencies and mode shapes of an elastic, fluid-filled spherical shell containing a concentrically located elastic sphere. The major assumptions are that the fluid is inviscid, the spherical shell is thin, and the modes of the physical system are axisymmetric. An analytical modal analysis results in a characteristic equation for the natural frequencies of the physical system. Roots of the characteristic equation were found numerically. The results show that the spectra of natural frequencies for the physical system are distorted by the combined effects of the elasticity of the inner sphere and the reduction of fluid volume due to the inner sphere. The elastic inner sphere also introduces a pattern of additional frequencies to the spectra of natural frequencies of the physical system.

Stethoscope-based detection of detorqued bolts using impact-induced acoustic emissions

Non-invasive impact analysis can be used to detect loosened bolts in a steel structure composed of construction-grade I beams. An electronically enhanced stethoscope was used to acquire signals from a moderate to light impact of a hammer on a horizontal steel I beam. Signals were recorded by placing the diaphragm of the stethoscope on the flange of either the horizontal beam or the vertical column proximal to a bolted connection connecting the two members. Data were taken using a simple open-loop method; the input signal was not recorded, nor was it used to reference the output signal. The bolted connection had eight bolts arranged in a standard configuration. Using the “turn of the nut” standard outlined by the Research Council on Structural Connections (RCSC, TDS-012 2-18-08), the bolted joint was tested in three conditions: turn of the nut tight, finger tight, and loose. We acquired time-based data from each of 52 patterns of the eight bolts in three conditions of tightness. Results of both time and frequency-based analyses show that open-loop responses associated with detorqued bolts vary in both amplitude decay and frequency content. We conclude that a basic mechanism can be developed to assess the structural health of bolted joints. Results from this project will provide a framework for further research, including the analysis of welded joints using the same approach.

Acoustic detection of bolt detorquing in structures

Recent interest in structural health of bridges and large buildings has lent new urgency to the development and enhancement of theories and methods in the field of nondestructive testing. We demonstrate a simple technique for acquiring data from an impact test using a basic electronic stethoscope. The continuous wavelet transform (CWT) is used to process and display the transient responses of a bolted joint in a structure with bolts installed in a properly tightened manner and bolts incorrectly installed. Results for tight and loose bolts are compared using the semblance analysis approach described by Cooper and Cowan [“Comparing time series using wavelet‐based semblance analysis,” Computers & Geosciences 34, 95–102 (2008)]. We enhance the interpretation of results using speaker‐driven audio output synthesized from CWT and semblance analysis.

Detection of structural bolt detorquing using direct acoustic measurement

A method for detecting loosened bolts in a structural joint based upon open-loop acoustic measurement is presented. The acoustic measurement is taken direclty on the bolt head. The response of the bolt to a proximal hammer impact is evaluated and characterised using wavelet decomposition of the signal measured from the bolt head. Results are presented from a set of structural bolts in several conditions of preload and looseness. The study could enable a quick and simple method for detecting and evaluating detorqued bolts in structural joints.

Detection of structural bolt detorquing using direct stethoscope measurement

A method for detecting loosened bolts in a structural joint based upon open-loop acoustic measurement is presented. The acoustic measurement is taken directly on the bolt head. The response of the bolt to a proximal hammer impact is evaluated and characterized using wavelet decomposition of the signal measured from the bolt head. Data were also taken from an accelerometer mounted longitudinally and transversely on the bolt head. Results from the stethoscope and the accelerometer are presented from a set of structural bolts in several conditions of preload and looseness. A stethoscope applied to the loose bolt and a proximal bolt during impact recorded a marked difference between tight, finger tight, and loose bolts. The study could enable a quick and simple method for detecting and evaluating detorqued bolts in structural joints.

Audio enhancement of biomechanical impact data.

Analysis and interpretation of impact data from a force transducer or accelerometer can be augmented and enhanced using audio playback. Trends and differences which may be difficult to identify using data imagery can be elucidated and reinforced by converting digital data from a force plate to an audio signal, which can then be played through a high‐quality speaker system. The audio stream can be processed using standard acoustical methods such as tempo and pitch shifting, which can emphasize frequencies and tone bursts for improved signal characterization. We apply audio enhancement to data from two separate biomechanical studies: (1) a drop landing experiment for the investigation of gender differences in impact upon landing and (2) an experiment for the investigation of impact differences between cleated and noncleated shoes on artificial turf. The continuous wavelet transform (CWT) is used to process data from a force plate in both studies. Results are compared using the semblance analysis approach de...

Application of the continuous wavelet transform to acoustic emissions generated by joint and muscle motion

The subject matter of this presentation will refer to the preliminary development of a non‐destructive and non‐invasive diagnostic method using low‐frequency acoustic emissions to characterize and diagnose joint and muscle disorders. Low‐frequency acoustic emissions have had limited effectiveness when used in the past to characterize and diagnose joint and muscle disorders because Fourier transform techniques were not capable of describing when a specific frequency occurred during an acoustic emission event. With the development of techniques that decompose a signal into time‐frequency representations using wavelet analysis it is now possible to describe complex transient signals. While the continuous wavelet transform (CWT) method has already made an impact within many areas of the medical sciences such as EEG analysis, ECG analysis, and DNA‐sequence analysis, the method is now becoming popular for analyzing muscle and joint acoustic emissions from the hip, knee, and elbow joints. This paper will present...