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Background: The Lachman test is clinically considered to be a reliable physical examination for anterior cruciate ligament (ACL) deficiency. However, the test involves subjective judgement of differences in tibial translation and endpoint quality. An auscultation system has been developed to allow assessment of the Lachman test. The knee joint sound during the Lachman test was analyzed using fast Fourier transformation. The purpose of the present study was to quantitatively evaluate knee joint sounds in healthy and ACL-deficient human knees., Methods: Sixty healthy volunteers and 24 patients with ACL injury were examined. The Lachman test with joint auscultation was evaluated using a microphone. Knee joint sound during the Lachman test (Lachman sound) was analyzed by fast Fourier transformation. As quantitative indices of the Lachman sound, the peak sound (Lachman peak sound) as the maximum relative amplitude (acoustic pressure) and its frequency were used., Results: In healthy volunteers, the mean Lachman peak sound of intact knees was 100.6 Hz in frequency and -45 dB in acoustic pressure. Moreover, a sex difference was found in the frequency of the Lachman peak sound. In patients with ACL injury, the frequency of the Lachman peak sound of the ACL-deficient knees was widely dispersed. In the ACL-deficient knees, the mean Lachman peak sound was 306.8 Hz in frequency and -63.1 dB in acoustic pressure. If the reference range was set at the frequency of the healthy volunteer Lachman peak sound, the sensitivity, specificity, positive predictive value, and negative predictive value were 83.3%, 95.6%, 95.2%, and 85.2%, respectively., Conclusion: Knee joint auscultation during the Lachman test was capable of judging ACL deficiency on the basis of objective data. In particular, the frequency of the Lachman peak sound was able to assess ACL condition., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: Vibration response imaging (VRI) records the intensity and distribution of lung sounds during the respiration cycle. Our objective was to analyze VRI findings in healthy Japanese adults., Methods: VRI images of 106 healthy subjects (33.7±9.6 years, 52 male and 54 female), including 67 nonsmokers and 39 asymptomatic smokers, were recorded. The regional intensity of vibrations was assessed using quantitative lung data (QLD), and VRI dynamic images by rater assessment, left and right lung asynchrony (gap index), and regional lung asynchrony (asynchrony score)., Results: A dominance of total left lung QLD was observed in all subjects, and this phenomenon was more prominent in female subjects. However, there was no significant difference between the total left and total right lung QLD in smokers. Rater assessments showed that 81.1% of all subjects had a normal final assessment. Male subjects had a significantly higher percentage of good or normal assessments for all image scores, except dynamic image scoring. The asynchrony score was significantly higher in female subjects. There were no significant differences in these qualitative assessments between non-smokers and smokers., Conclusions: Although our QLD results were similar to those of a previous report, there were discrepancies between sexes for the qualitative assessments. A significantly higher number of female subjects had abnormal images as assessed by the raters. Furthermore, significantly higher asynchrony scores were observed in female subjects. The VRI variability in sex may be considered normal among the Japanese population. This study is registered with UMIN-CTR under registration number UMIN000002355., (Copyright © 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.)

Background: Respiratory rate should be monitored continuously in the post-anaesthesia care unit (PACU) to avoid any delay in the detection of respiratory depression. Capnometry is the standard of care but in extubated patients requires a nasal cannula or a face mask that may be poorly tolerated or can be dislodged, leading to errors in data acquisition and false alarms. The value of a new non-invasive acoustic monitor in this setting has not been fully investigated., Methods: Adult patients admitted to the PACU after general anaesthesia were included. After tracheal extubation, an adhesive sensor with an integrated acoustic transducer (RRa™) was placed on the patient's throat and connected to its monitor while the patient breathed through a face mask with a carbon dioxide sampling port (Capnomask™) connected to a capnometer. Both the acoustic monitor and the capnometer were connected to a computer to record one pair of data per second for up to 60 min., Results: Fifty-two patients, mean (range) age 54 (22-84) yr and BMI 26 (19-39) kg m(-2), were studied. Compared with capnometry, the bias and limits of agreement of the acoustic method were 0 (-1.4-1.4) bpm. The acoustic sensor was well tolerated while the face mask was removed by eight patients, leading to study discontinuation in two patients., Conclusions: In extubated patients, continuous assessment of respiration rate with an acoustic monitor correlated well with capnometry.

Rationale: The standardized use of a stethoscope for chest auscultation in clinical research is limited by its inherent inter-listener variability. Electronic auscultation and automated classification of recorded lung sounds may help prevent some of these shortcomings., Objective: We sought to perform a systematic review and meta-analysis of studies implementing computerized lung sound analysis (CLSA) to aid in the detection of abnormal lung sounds for specific respiratory disorders., Methods: We searched for articles on CLSA in MEDLINE, EMBASE, Cochrane Library and ISI Web of Knowledge through July 31, 2010. Following qualitative review, we conducted a meta-analysis to estimate the sensitivity and specificity of CLSA for the detection of abnormal lung sounds., Measurements and Main Results: Of 208 articles identified, we selected eight studies for review. Most studies employed either electret microphones or piezoelectric sensors for auscultation, and Fourier Transform and Neural Network algorithms for analysis and automated classification of lung sounds. Overall sensitivity for the detection of wheezes or crackles using CLSA was 80% (95% CI 72-86%) and specificity was 85% (95% CI 78-91%)., Conclusions: While quality data on CLSA are relatively limited, analysis of existing information suggests that CLSA can provide a relatively high specificity for detecting abnormal lung sounds such as crackles and wheezes. Further research and product development could promote the value of CLSA in research studies or its diagnostic utility in clinical settings., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Objective: To determine the usefulness of an acoustic device to confirm correct placement of extradural needles in horses., Study Design: Prospective experimental study., Animals: Twelve adult healthy horses weighing between 434 and 640 kg., Materials and Methods: Horses were sedated, placed in stocks and subjected to caudal extradural anaesthesia using lidocaine 2%. For extradural puncture an 18 gauge Tuohy needle connected to an acoustic device via an electronic pressure transducer was used. This device allowed recording of the extradural pressure profile and the transformation of pressure changes into an audible signal. Extradural needle advancement was stopped and the local anaesthetic administered when either a sharp decrease in sound pitch occurred or a 'pop' sensation was felt. Correct needle placement was assessed clinically by the degree of extradural anaesthesia present using needle prick stimuli, loss of tail tone and occurrence of localized sweating. Descriptive statistical analysis was used for evaluation of the data., Results: Extradural anaesthesia was successful in nine of 12 horses. In these horses during extradural needle advancement the pitch of the audible signal first increased and abruptly changed to a constant low pitched sound. In the three horses with unsuccessful punctures only a slight decrease of the pitch was noted. A 'pop' was clearly distinguished in five of nine horses with successful extradural puncture. In four horses a 'pop' was not present despite correct extradural needle placement. In three horses with incorrect needle placement a 'pop' was present. In the horses with correct needle positioning the median extradural pressure after the puncture was -0.8 kPa (-6 mmHg)., Conclusion and Clinical Relevance: The acoustic device is useful to assist in the identification of successful or unsuccessful extradural needle placement in the horse.

Objective: Patients with interstitial pulmonary fibrosis (IPF) often have diffusely abnormal findings on chest radiographs, making it difficult to detect evidence of superimposed congestive heart failure (CHF) or pneumonia. The goal of this study was to determine whether the crackles of IPF differed in their transmission and frequency from crackles of CHF and pneumonia in the hope of improving diagnosis and monitoring of these patients., Methods: A multichannel lung sound analyzer was used to collect 20-s samples of sound from 25 patients with pneumonia, 17 patients with CHF, and 19 patients with IPF. We calculated a crackle transmission coefficient (CTC) by quantifying the distance a crackle spreads using a technique that cross-correlated the signal containing the highest amplitude crackle with the corresponding signal on all other ipsilateral channels: CTC, 0% = no transmission; CTC, 100% = equal transmission to all channels., Results: Both the CTC and the crackle frequency in IPF were statistically different from that in CHF and pneumonia (p < 0.0001). The CTC averaged 24 +/- 5% for pneumonia, 25 +/- 8% for CHF, and 14 +/- 4% for IPF. The crackle frequency averaged 302 +/- 47 Hz for pneumonia, 311 +/- 62 Hz for CHF, and 462 +/- 50 Hz for IPF (+/- SD)., Conclusion: These differences in CTC and crackle frequency offer the promise of helping guide treatment in IPF patients.

The appearance of wheezes and changes in inspiratory breath (vesicular) sound intensity (BSI) were monitored in patients undergoing routine methacholine challenge test (MCT). The results were compared with changes in spirometry and to airway hyper-responsiveness (AH). Fifty-four patients were examined. Spirometry was performed before and after the inhalation of cumulative doses of methacholine starting from 25 micrograms; a fall in forced expiratory volume in 1 s (FEV1) by 20% or more was considered as significant. Lung auscultation was performed by two observers simultaneously using a special stethoscope placed sequentially over the posterior right and left upper (interscapular region, 5 cm from the fourth thoracic vertebra) and lower lung zones (5 cm below the scapulae). Symptoms were recorded by the patients on a visual analogue scale. In 27 patients, the MCT was positive (MCT+) and in 27 patients it was negative (MCT-). Wheezes were identified at PD20 in 12 MCT+ patients while reduced BSI alone was found in 11 patients; in four patients, auscultation was normal. In 20 MCT+ patients, either wheezes, diminished BSI or both were heard, one to several steps before reaching PD20. In the MCT- group, wheezes were detected in two patients and diminished BSI in four. In MCT+ patients, the mean (+/-SD) perception of symptoms at end-challenge was 33% (+/-26), whereas in MCT- patients, it was 13.6% (+/-22). Complete inter-observer agreement was found in 95.7% of auscultations performed (Kappa coefficient = 0.846). Coupled to spirometry, lung auscultation may prove useful in airway challenge testing provided the concept is accepted that wheeze appearance and, by extension, an acute decrease in BSI, is as legitimate a manifestation of AH as a fall in FEV1.

Egophony is a change in timbre (Ee to A) but not pitch or volume. It is due to a decrease in the amplitude and an increase in the frequency [corrected] of the second formant, produced by solid (including compressed lung) interposed between the resonator and the stethoscope head. This explains certain difficulties in learning this valuable but currently neglected sign as well as in understanding certain physiologic false-positive occurrences.

The use of electret microphones to measure lung sounds is widespread because of their small size, high fidelity, and low cost. Typically, an air cavity is placed between the skin surface and the microphone to convert the chest wall vibrations into a measurable sound pressure. The importance of air cavity depth on this transduction process was investigated in this study. An acoustic model of chest wall--air cavity--microphone interface was developed and the predicted effects of depth were compared with measurements performed using an artificial chest wall and lung sounds from a healthy subject. Model predictions are in general agreement with both in vitro and in situ measurements and indicate that the overall high-frequency response of the transduction diminishes with increasing cavity depth. This finding suggests that smaller cavity depths are more appropriate for detection of lung sounds over a wide band width and stresses the importance of coupler size on microphone measurements.

We assessed the performance of three air-coupled and four contact sensors under standardized conditions of lung sound recording. Recordings were obtained from three of the investigators at the best site on the posterior lower chest as determined by auscultation. Lung sounds were band-pass filtered between 100 and 2,000 Hz and sampled simultaneously with calibrated airflow at a rate of 10 kHz. Fourier techniques were used for power spectral analysis. Average spectra for inspiratory sounds at flows of 2 +/- 0.5 L/s were referenced against background noise at zero flow. Air-coupled and contact sensors had comparable maximum signal-to-noise ratios and gave similar values for most spectral parameters. Unexpectedly, less sensitivity (lower signal-to-noise ratio) at high frequencies was observed in the air-coupled devices. Sensor performance needs to be characterized in studies of lung sounds. We suggest that lung sound spectra should be averaged at known airflows over several breaths and that all measurements should be reported relative to sounds recorded at zero flow.

We have compared two non-invasive methods of arterial pressure (AP) measurement used in labour wards: an automatic oscillometric measurement obtained by Dinamap 1846, and a conventional auscultatory measurement obtained by midwives. A total of 369 AP measurements were recorded, involving 28 normotensive and hypertensive pregnant women during labour, with or without extradural analgesia. Compared with the midwife group, the Dinamap group had a greater systolic AP, by 2.7 mm Hg (P < 0.01) and smaller diastolic AP, by 9.8 mm Hg (P < 0.01). The correlations between the two methods were highly significant, but the limits of agreement were relatively wide for both systolic and diastolic AP measurements. We conclude that a clinically important difference exists in diastolic AP measurements. Dinamap diastolic AP must be corrected using a regression equation, or simply by adding 10 mm Hg, before being compared with the available normal and hypertensive AP values.

During whole body radiation therapy of children, treatment may be done in places not equipped with acceptable scavenging systems for anesthetic gases and where clinical observation of the patient may be impossible. In order to solve this problem, the authors have used a total intravenous (IV) anesthetic technique using midazolam, pancuronium, and fentanyl. With midazolam as the only hypnotic agent, the problem with scavenging is solved, and a computer simulation of the plasma concentration of midazolam is presented. A modified stethoscope for monitoring during radiation also has been developed. This anesthetic technique and the stethoscope have been used in seven children. The total IV anesthesia proved to be a useful method for children during whole body radiation. The modified stethoscope functioned very well and was a useful complement to the monitoring equipment.

Pulmonary sounds were recorded before and after bronchodilator treatment in 20 patients with acute attacks of asthma. Analysis of the sounds showed that improvement in the forced expiratory volume in one second was associated with the following two changes in the sound signal: (1) the proportion of the respiratory cycle occupied by wheeze (Tw/Ttot ratio) was reduced from 86 percent to 31 percent on average; and (2) the sound frequency of the highest pitched wheeze was also reduced, from a mean of 440 Hz to 298 Hz.

The assessment of digital artery blood flow in human beings would ideally be noninvasive and accurate. The transcutaneous use of a high-resolution 20 MHz ultrasonic pulsed Doppler provides information about average blood velocities, vessel lumen diameters, and velocity profiles in small vessels. These data are used in calculations which quantitate blood flow in human digital arteries.

We evaluated blinded readings by a physician using a miniature real-time "ultrasound stethoscope" compared with a "standard" echo instrument used by an independent physician. Size of all four cardiac chambers, wall motion, all four valves, thickness of interventricular septum and left ventricular posterior wall, and pericardial effusion were assessed in 66 patients. Each physician estimated whether he had answered the referring question and gave a final diagnosis. The physician using the ultrasound stethoscope correctly assessed chamber size in 87 percent of cases, segmental left ventricular wall motion in 71 percent of segments studied, and wall thickness in 88 percent of cases, and the diagnosis by the ultrasound stethoscope agreed with that made by the standard instrument in 68 percent of cases. The physician with the ultrasound stethoscope detected structural valvular problems (eg, stenosis) in 70 percent of cases but only detected flow abnormalities (eg, regurgitation) in 14 percent of cases. We conclude that (1) an experienced echocardiographer using an ultrasound stethoscope can detect most structural abnormalities found by a standard echocardiographic instrument; (2) chamber size, valvular stenosis, and pericardial effusions were accurately assessed; (3) the ultrasound stethoscope cannot be used to detect valvular regurgitation; and (4) limitations include the lack of freeze-frame, M-mode, hard copy, and Doppler.

This study was conducted on 50 patients in the Central Institute of Orthopaedics, Safdarjung Hospital, New Delhi, from June to October 1985. With the help of a child's stethoscope and a tuning fork of 128 Hz, the sound conducted by an injured limb was compared with that by the uninjured limb. The presence of a fracture reduced or abolished the conduction of sound by a bone. This method allows a quick examination without causing any pain, which is an advantage in an uncooperative patient. It is also reliable in the unconscious. The test is so simple that paramedical staff can use it. The results were correct in 94 per cent of patients and were confirmed by radiological examination whereas clinical diagnosis was correct in only 88 per cent of cases.

A novel technique for auscultating an aortopulmonary shunt murmur utilizing the principle of conduction of sounds through a closed air system is described.

One hundred forty-nine consecutive patients who had peripheral arterial disease (PAD) with clinically audible asymptomatic bruits were studied. Sixty-two of these patients were age- and sex-matched with 62 PAD patients in whom no bruits were detected. The PAD was demonstrated by angiography or by the 1-minute exercise test. Clinical assessment was performed every 6 months and oculoplethysmography and carotid phonoangiography (OPG/CPA) were performed every year. Angiography and reconstructive surgery were performed only if symptoms of transient ischemic attack (TIA) or stroke occurred. Life-table analysis revealed that over a 5.5-year follow-up, 32% of 211 PAD patients were expected to die. In the control study 45% of bruit patients and 32% of control patients were expected to die (no significant difference). Myocardial infarction accounted for 59% of deaths in the bruit group compared with 28% in the control group (no significant difference). TIA occurred more commonly in the bruit group (26.5%) than in the controls (6%) (p less than 0.02). However, stroke without warning occurred in 9% of bruit patients compared with 8% of controls (no significant difference). It is concluded that for asymptomatic carotid bruit it is safe to wait for the onset of symptoms before angiography and corrective reconstructive surgery.