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At least 667 records · Page 37Linked to original sources
PubMed2005

Detection of the third heart sound using a tailored wavelet approach: method verification.

Heart sounds can be considered as mechanical fingerprints of myocardial function. The third heart sound normally occurs in children but disappears with maturation. The sound can also appear in patients with heart failure. The sound is characterised by its low-amplitude and low-frequency content, which makes it difficult to identify by the traditional use of the stethoscope. A wavelet-based method has recently been developed for detection of the third heart sound. This study investigated if the third heart sound could be identified in patients with heart failure using this detection method. The method was also compared with auscultation using conventional phonocardiography and with characterisation of the patients with echocardiography. In the first study, 87% of the third heart sounds were detected using the wavelet method, 12% were missed, and 6% were false positive. In study 2, the wavelet-detection method identified 87% of the patients using the third heart sound, and regular phonocardiography identified two (25%) of the subjects.

Adult↗
PubMed1989

The Korotkoff sound.

As the auscultatory method of blood pressure measurement relies fundamentally on the generation of the Korotkoff sound, identification of the responsible mechanisms has been of interest ever since the introduction of the method, around the turn of the century. In this article, a theory is proposed that identifies the cause of sound generation with the nonlinear properties of the pressure-flow relationship in, and of the volume compliance of the collapsible segment of brachial artery under the cuff. The rising portion of a normal incoming brachial pressure pulse is distorted due to these characteristics, and energy contained in the normal pulse is shifted to the audible range. The pressure transient produced is transmitted to the skin surface and stethoscope through deflection of the arterial wall. A mathematical model is formulated to represent the structures involved and to compute the Korotkoff sound. The model is able to predict quantitatively a range of features of the Korotkoff sound reported in the literature. Several earlier theories are summarized and evaluated.

Auscultation↗
PubMed1997

Asymmetry of respiratory sounds and thoracic transmission.

Breath sounds heard with a stethoscope over homologous sites of both lungs in healthy subjects are presumed to have similar characteristics. Passively transmitted sounds introduced at the mouth, however, are known to lateralise, with right-over-left dominance in power at the anterior upper chest. Both spontaneous breath sounds and passively transmitted sounds are studied in four healthy adults, using contact sensors at homologous sites on the anterior upper and posterior lower chest. At standardised air flow, breath sound intensity shows a right-over-left dominance at the anterior upper chest, similar to passively transmitted sounds. At the posterior lung base, breath sounds are louder on the left, with a trend to similar lateralisation in transmitted sounds. It is likely that the observed asymmetries are related to the effects of cardiovascular structures and airway geometry on sound generation and transmission.

Adult↗
PubMed1995

Confounders of auscultatory blood pressure measurement.

The appropriate use of any test requires the clinician to appreciate that test's limitations. By recognizing the potential confounders of the auscultatory assessment of blood pressure, the clinician minimizes the likelihood of enacting therapeutic decisions based on inaccurate data. When approaching the treatment of a hypertensive patient, several points should be kept in mind. First, the measurement of persistent and severe hypertension in a patient receiving treatment who describes symptoms of orthostatic hypotension with apparently adequate standing blood pressure or who lacks corroborating retinal, echocardiographic, or electrocardiographic signs of hypertension should raise the concern of pseudohypertension or a white-coat response. Similarly, when one finds a normal or near-normal systolic blood pressure in a patient with a clinical picture consistent with severe hypertension, one should make a directed effort to look for an unrecognized auscultatory gap. Second, marked discrepancies in measurements as obtained by different operators or in different settings should raise concern of the white-coat response or methodologic errors by one operator, such as undercuffing, excessive pressure on the head of the stethoscope, rapid deflation of the cuff, or use of different arms. In treating hypertension in even the minimally obese patient, a special point must be made that an adequate size cuff be used for all blood pressure determinations. Third, when blood pressure is determined with the patient in any but the satndardized back-and-arm-supported seated position described above, the clinician should acknowledge the possibility that the position may alter the patient's classification. Fourth, the diagnosis and management of hypertension requires multiple measurements of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Auscultation↗
PubMed2002

The development and clinical application of acoustical technique in hip joint.

A non-invasive acoustical system was developed for the measurement of transmission properties of acoustic waves in the hip joints. The instrumentation consisted of three sub-systems. An excitation system employed a vibratory force at the sacrum of the test subjects. A transduction system included a pair of identical microphones installed in the tubes of two stethoscopes, which were placed at the greater trochanters on both sides for picking up the acoustical signals transmitted across the hip joints. The data acquisition and analysis system was a portable signal analyzer with a program of dual channel digital filter for measuring the power of acoustical signal in 1/3-octave frequency bands. 27 normal adults, 20 normal pre-school children and 40 normal neonates were randomly selected for testing. Coherence function (CF) and discrepancy (D) was measured during the testing. Results from the three groups showed that there was a high coherence of the signals (CF > 0.9) and a small discrepancy (D < 3 dB) between bilateral hips in the frequency range of 200-315 Hz. For normal neonates, there was a wider frequency range of 160-315 Hz in which the acoustical signals maintained a high coherence (CF > 0.93) and a smaller discrepancy (D < 2 dB) was observed. This study showed that the development of the acoustical technique provided a practical method with objective parameters. The results obtained in this study can offer a baseline for further investigation of hip disorders particularly those related to structural abnormalities of the hip.

Acoustic Stimulation↗
PubMed1993

Tracheal tube leak test--is there inter-observer agreement?

Although the leak test is recommended as a method of assessing the appropriate size of uncuffed endotracheal tubes for use in children, the reproducibility of this test has not been validated. Patients from newborn to ten years of age requiring tracheal intubation for elective surgery were studied. The endotracheal tube size was calculated using the formula: (age + 16) divided by 4 for patients > or = two years of age and at the discretion of the attending anaesthetist for patients < two years of age. After the induction of anaesthesia and administration of a nondepolarizing muscle relaxant, the patient's trachea was intubated and mid-tracheal placement was confirmed. Two of the three staff anaesthetists participating in the study assessed the leak pressure consecutively. Each participant performed a single leak determination. The leak pressure was determined as follows: the patient was supine with the head in a neutral position, fresh gas flowed into the breathing circuit at 5 L.min-1, a stethoscope was placed on the skin over the larynx and the pressure relief valve was completely closed. Pressure slowly increased in the breathing circuit until an audible leak occurred around the tracheal tube. The inter-observer difference was calculated in 212 patients. The absolute value of the difference between that of two observers increased as the mean leak pressure increased. However, the variation between observers expressed as a percent of the absolute measurement remained constant. An average variance in measurement of 38% was found at both low and high leak pressures. In conclusion, we found considerable variation between two experienced observers in assessing leak pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Auscultation↗
PubMed1994

Mask lung ventilation by ambulance personnel: a performance assessment.

We evaluated the ability of basic life support ambulance officers and anaesthetists to perform lung ventilation with a face mask. After induction of anaesthesia and institution of standardized airway conditions the ambulance officer or anaesthetist placed a mask on the patient's face and lung ventilation was commenced. The order of hand grip (one vs two hands) was randomized. The mask was connected to a ventilator which had flow and pressure transducers in the inspiratory and expiratory breathing circuits. The output of these devices was sent to an electronic integrator to determine volumes. Calibration of the flow transducers was made against a spirometer while ventilating a test lung. Oesophageal insufflation was determined by listening over the epigastrium with a stethoscope. Data collected included presence of gastro-oesophageal insufflation, inspiratory and expiratory volumes. Expiratory volumes for ambulance officers and anaesthetists at 30 cm H2O were greater than that of ambulance officers at 20 cm H2O (P < 0.001) but profession of the mask holder or hand grip had no effect on expiratory volume. There was no difference in the mask leak when the professions were compared but ambulance officers had a lower mask leak with a two-handed grip at 20 cm H2O (P < 0.001). Anaesthetists had a greater incidence of gastro-oesophageal insufflation when a two-handed mask grip was utilized (P < 0.05). In healthy relaxed patients there appeared to be little difference between the ambulance officers and qualified anaesthetists in airway maintenance or mask-holding ability.

Adolescent↗
PubMed1996

[Infrared temperature measurement in the ear canal with the DIATEK 9000 Instatemp and the DIATEK 9000 Thermoguide. Comparison with methods of temperature measurement in other body parts].

UNLABELLED: Temperature of the tympanic membrane is recommended as a "gold standard" of core-temperature recording. However, use of temperature probes in the auditory canal may lead to damage of tympanic membrane. Temperature measurement in the auditory canal with infrared thermometry does not pose this risk. Furthermore it is easy to perform and not very time-consuming. For this reason infrared thermometry of the auditory canal is becoming increasingly popular in clinical practice. We evaluated two infrared thermometers-the Diatek 9000 Thermoguide and the Diatek 9000 Instatemp-regarding factors influencing agreement with conventional tympanic temperature measurement and other core-temperature recording sites. In addition, we systematically evaluated user dependent factors that influence the agreement with the tympanic temperature. MATERIALS AND METHODS: In 20 volunteers we evaluated the influence of three factors: duration of the devices in the auditory canal before taking temperature (0 or 5 s), interval between two following recordings (30, 60, 90, 120, 180 s) and positioning of the grip relative to the auditory-canal axis (0, 60, 180 and 270 degrees). Agreement with tympanic contact probes (Mon-a-therm tympanic) in the contralateral ear was investigated in 100 postoperative patients. Comparative readings with rectal (YSI series 400) and esophageal (Mon-a-therm esophageal stethoscope with temperature sensor) probes were done in 100 patients in the ICU. The method of Bland and Altman was taken for comparison. RESULTS: Shortening of the interval between two consecutive readings led to increasing differences between the two measurements with the second reading decreasing. A similar effect was seen when positioning the infrared thermometers in the auditory canal before taking temperatures: after 5 s the recorded temperatures were significantly lower than temperature recordings taken immediately. Rotation of the devices out of the telephone handle position led to increasing lack of agreement between infrared thermometry and contact probes. Mean differences between infrared thermometry (Instatemp and Thermoguide, CAL-Mode) and tympanic probes were -0.41 +/- 0.67 degree C (2 SD) and -0.43 +/- 0.70 degree C, respectively. Mean differences between the Thermoquide (Rectal-Mode) and rectal probe were -0.19 +/- 0.72 degree C, and between the Thermoguide (Core Mode) and esophageal probe -0.13 +/- 0.74 degree C. DISCUSSION: Although easy to use, infrared thermometry requires careful handling. To obtain optimal recordings, the time between two consecutive readings should not be less than two min. Recordings should be taken immediately after positioning the devices in the auditory canal. Best results are obtained in the 60 degrees position with the grip of the devices following the ramus mandibulae (telephone handle position). The lower readings of infrared thermometry compared with tympanic contact probes indicate that the readings obtained represent the temperature of the auditory canal rather than of the tympanic membrane itself. To compensate for underestimation of core temperature by infrared thermometry, the results obtained are corrected and transferred into core-equivalent temperatures. This data correction reduces mean differences between infrared recordings and traditional core-temperature monitoring, but leaves limits of agreement between the two methods uninfluenced.

Body Temperature↗
PubMed1997

[Determination of core body temperature. A comparison of esophageal, bladder, and rectal temperature during postoperative rewarming].

OBJECTIVE: The data of 60 postoperatively sedated and ventilated patients were studied for analysis of oesophageal, bladder, and rectal temperatures. The purpose of the investigation was to clarify whether changes of oesophageal temperature are adequately reflected by bladder and rectal temperatures and whether the rate of rewarming has an influence on the accuracy of the latter two sites. METHODS: For temperature recording, a Hi-Lo Temp esophageal stethoscope (Mallinckrodt Medical), a Foley FC400-18 catheter temperature sensor (Respiratory Support Products, Mallinckrodt Medical), and a rectal temperature probe N401 (YSI) were used. Each probe and matching recording unit was calibrated over a range of 30-40 degrees C against a reference quartz thermometer (Hewlett packard Model 2801 A) in a thermostated water bath before the investigation. Five measuring points distributed over the whole period of rewarming were evaluated. Patients were assigned to groups with slow and fast rewarming, respectively. Agreement between the methods of measurement was assessed as described by Bland and Altman. Furthermore, differences between the oesophageal and bladder or rectal temperature were checked at each measuring point for statistical significance using the t-test. RESULTS: In regard to oesophageal temperature, the bladder and rectal temperatures had biases of -0.01 degree C and -0.03 degree C, respectively. Limits of agreement (+/- s) were +/-0.68 degree C and +/-0.82 degree C, respectively. The bias of the bladder temperature was independent of the rate of rewarming (Fig. 3). The bias of the rectal temperature, however, differed in regard to the rewarming rate, being +0.06 degree C in the group with slow rewarming and -0.13 degree C in the group with fast rewarming (Tables 1 and 2, Fig. 1 and 2). These differences were significant for the measuring points 4 and 5 (Fig. 4). CONCLUSIONS: Bladder and rectal temperatures can accurately indicate the oesophageal temperature with a very small bias in postoperatively sedated and ventilated patients. Since the rate of rewarming influences the accuracy of rectal temperature readings, monitoring of bladder temperature seems to be more favourable in the postoperative period.

Body Temperature↗
PubMed2005

Intraoperative gastroscopy for gastric surgery.

BACKGROUND: Few reports are available on the use of intraoperative gastroscopy for gastric surgery. METHODS: The details of 33 patients (25 early gastric cancers and eight gastric submucosal tumors) who underwent intraoperative gastroscopy from June 2003 to June 2004 were analyzed. The type of operation or resection margin was determined by evaluating both sides of the stomach simultaneously by combined operative and gastroscopic methods. RESULTS: Preoperative endoscopic clipping was done preferentially for early gastric cancer. However, when precise localization was needed, intraoperative gastroscopy was used. Curative gastric resection was possible in 25 early gastric cancer patients after accurate lesion localization. Laparoscopic wedge resections of submucosal tumors were performed in seven patients without stenosis by combined laparoscopic and gastroscopic methods. CONCLUSIONS: Intraoperative gastroscopy can be used effectively during gastric surgery for early gastric cancer or submucosal tumors and can be regarded as a modern stethoscope to gastric surgeons.

Gastric Mucosa↗
PubMed2005

Computer-based detection and analysis of heart sound and murmur.

To develop a digital algorithm that detects first and second heart sounds, defines the systole and diastole, and characterises the systolic murmur. Heart sounds were recorded in 300 children with a cardiac murmur, using an electronic stethoscope. A Digital algorithm was developed for detection of first and second heart sounds. R-waves and T-waves in the electrocardiography were used as references for detection. The sound signal analysis was carried out using the short-time Fourier transform. The first heart sound detection rate, with reference to the R-wave, was 100% within 0.05-0.2R-R interval. The second heart sound detection rate between the end of the T-wave and the 0.6R-R interval was 97%. The systolic and diastolic phases of the cardiac cycle could be identified. Because of the overlap between heart sounds and murmur a systolic segment between the first and second heart sounds (20-70%) was selected for murmur analysis. The maximum intensity of the systolic murmur, its average frequency, and the mean spectral power were quantified. The frequency at the point with the highest sound intensity in the spectrum and its time from the first heart sound, the highest frequency, and frequency range were also determined. This method will serve as the foundation for computer-based detection of heart sounds and the characterisation of cardiac murmurs.

Adolescent↗
PubMed2006

Feature extraction for systolic heart murmur classification.

Heart murmurs are often the first signs of pathological changes of the heart valves, and they are usually found during auscultation in the primary health care. Distinguishing a pathological murmur from a physiological murmur is however difficult, why an "intelligent stethoscope" with decision support abilities would be of great value. Phonocardiographic signals were acquired from 36 patients with aortic valve stenosis, mitral insufficiency or physiological murmurs, and the data were analyzed with the aim to find a suitable feature subset for automatic classification of heart murmurs. Techniques such as Shannon energy, wavelets, fractal dimensions and recurrence quantification analysis were used to extract 207 features. 157 of these features have not previously been used in heart murmur classification. A multi-domain subset consisting of 14, both old and new, features was derived using Pudil's sequential floating forward selection (SFFS) method. This subset was compared with several single domain feature sets. Using neural network classification, the selected multi-domain subset gave the best results; 86% correct classifications compared to 68% for the first runner-up. In conclusion, the derived feature set was superior to the comparative sets, and seems rather robust to noisy data.

Aged↗
PubMed2005

The role of ultrasound in the diagnosis and management of psoriatic arthritis.

Psoriatic arthritis (PsA) presents many diagnostic, management and research challenges for rheumatologists who wish to obtain early diagnosis, differentiate synovitis and enthesitis, monitor disease activity accurately and objectively, prevent the development of structural damage, deliver local therapy accurately, and obtain PsA tissue for research purposes. Musculoskeletal ultrasound (MSUS) is widely used by European rheumatologists in their clinical practice to meet these challenges and has the potential to become the rheumatologist's stethoscope in Europe and North America. This paper examines the evidence that MSUS can improve clinical evaluation of patients with PsA for synovitis and enthesitis, that MSUS is more sensitive than plain radiography in detecting structural damage in joints, that MSUS can improve the success of joint aspiration and guide biopsy of PsA tissues. Recent exciting developments in the management of PsA are detailed including the role of power Doppler in the diagnosis of enthesitis in PsA, the role of MSUS in objective monitoring of disease activity, the evaluation of MSUS in the diagnosis of sacroiliitis, and the use of MSUS to guide therapeutic injection of the sacroiliac joints.

Arthritis↗
PubMed1979

Monitoring ventricular function at rest and during exercise with a nonimaging nuclear detector.

A portable nonimaging device, the nuclear stethoscope, for measuring beat to beat ventricular time-activity curves in normal people and patients with heart disease, both at rest and during exercise, is being developed and evaluated. The latest device has several operating modes that facilitate left ventricular and background localization, measurement of transit times and automatic calculation and display of left ventricular ejection fraction. The correlation coefficient of left ventricular ejection fraction obtained with the device and with a camera-computer system was 0.92 in 35 subjects. During bicycle exercise the ejection fraction in 15 normal persons increased from 44 to 64 percent (P less than 0.001), whereas among 12 patients with heart disease it was unchanged in 5 and decreased in 7.

Adult↗
PubMed1981

Noninvasive detection of left ventricular dysfunction with a portable electrocardiographic gated scintillation probe device.

A comparison of left ventricular function data derived from a low cost, portable electrocardiographic gated scintillation probe (nuclear stethoscope) with conventional scintiangiographic data was performed in 68 patients. Ejection fraction correlation (r = 0.86, p less than 0.005) was better in patients with uniform wall motion than in those with regional asynergy (r = 0.68 p less than 0.01). Probe variables reflecting systolic emptying rates, diastolic filling rates and timing intervals, and relative volumes analyzed in combination provided 100 percent sensitivity, specificity, and predictive value in detecting abnormal left ventricular performance. The results suggest that radionuclide angiography with an electrocardiographic gated scintillation probe is a sensitive, rapid and relatively inexpensive portable method of screening for cardiac dysfunction with a yield similar to that from the more costly gamma camera derived scintiangiogram.

Electrocardiography↗
PubMed1990

Validity of arm ergometer blood pressures immediately after exercise.

It is not possible to assess blood pressure (BP) by the standard cuff method during exercise primarily involving the arms. Consequently, such measurements are often taken immediately after (within 15 seconds) exercise. To assess the validity of this practice, 18 healthy men (mean age 32 years) who completed 3 progressive 3-minute workloads were studied during arm-crank ergometry. Ankle systolic BP was measured at the dorsalis pedis artery at seated rest, 15 seconds before completion of each exercise stage and immediately after each workload, using a Doppler stethoscope; simultaneous postexercise brachial systolic BPs were determined by auscultation. Brachial systolic BP during armcrank ergometry was estimated by the formula: (resting brachial systolic BP) + (exercise ankle systolic BP - resting ankle systolic BP). Brachial systolic BPs, obtained immediately after arm-crank ergometry, were significantly lower than those estimated during exercise (p less than 0.001), with corresponding mean values of 141 versus 153, 144 versus 173 and 151 versus 182 mm Hg at 150, 300, and 450 kg.m.min-1, respectively. The difference between measured (postexercise) and estimated pressures increased with progressive workloads. These findings indicate that systolic BPs taken by the standard cuff method immediately after arm-crank ergometry are likely to underestimate "true" physiologic responses.

Adult↗
PubMed1994

A history of the origin, evolution, and impact of electrocardiography.

The invention of the electrocardiograph by Dutch physiologist Willem Einthoven in 1902 gave physicians a powerful tool to help them diagnose various forms of heart disease, especially arrhythmias and acute myocardial infarction. The discovery of x-rays in 1895 and the invention of the electrocardiograph 7 years later inaugurated a new era in which various machines and technical procedures gradually replaced the physician's unaided senses and the stethoscope as the primary tools of cardiac diagnosis. These sophisticated new approaches provided objective information about the structure and function of the heart in health and disease. This review summarizes the origins and development of electrocardiography and addresses its role in defining cardiology as a specialty.

Angina Pectoris↗
PubMed1981

Laennec and the discovery of mediate auscultation.

The invention of the stethoscope by René Théophile Hyacinthe Laennec occurred within an emerging French tradition of bedside empiricism that combined physical diagnosis with autopsy correlation. On the occasion of the bicentennial of the birth of the discoverer of mediate auscultation, we celebrate the life and work of one of the founders of modern medicine.

Auscultation↗