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PubMedDate not supplied

Sonic detection of intracranial aneurysm and AVM.

This paper describes a method of detecting intracranial aneurysm and arteriovenous malformation (AVM) by analysing weak sounds produced by the blood circulation at the affected part. There is thought to be no turbulence in the normal cerebrovascular system, whereas abnormalities such as aneurysm and AVM sometimes cause turbulence in the blood flow. Thus, a small fraction of the flow energy might be converted into an acoustically detectable noise. For the detection of the sound, sensitive detectors must be applied close to the head since the sound is very weak, and, as in cerebrovascular diseases, the origin of the sound is usually concealed deep inside the hard shelter of the skull. The detection system we used had a gain of 40 to 50 dB greater than that of an ordinary stethoscope. The detection points were the teeth or forehead. Usually the sound started about 160 msec after the ventricular contraction and lasted for 100 to 400 msec. Its frequency component mostly ranged from 400 to 2000 Hz, but the spectrum profile changed according to the position and degree of abnormalities. The uttered sound was very random, which facilitated detection of the position of the sound origin by means of cross correlation methods using a pair of detectors. This method is completely noninvasive, causes no pain to the patient, and might be used even in mass examinations.

Adolescent↗
PubMed1980

Use of laryngeal sound recordings to monitor apnea.

Laryngeal sounds are produced by air flow across the glottis. We found that apnea could be identified by the cessation of laryngeal sounds during continuous monitoring. We recorded laryngeal sounds using a microphone coupled to a stethoscope head taped to the subject's lateral neck. This signal was conditioned using a commercially available amplifier and displayed on a time-based recorder. Laryngeal sound monitoring of apnea could be useful in sleep studies.

Adult↗
PubMed1986

Sound spectral analysis of voice-transmitted sound.

There is a change in voice-generated sound heard over an area of pulmonary consolidation described as the "e" to "a" change. The lung may act as a low pass filter with properties that are changed by consolidation. We studied 5 patients with pneumonia. Using an electronic stethoscope, we recorded the voice-generated sounds "e" and "9-9-9." Sound spectral analysis using the fast Fourier transformation technique was used to characterize the frequency spectrum of the recorded sound. This technique allowed us to evaluate the filter properties of the normal and consolidated lung. We found that the normal lung allowed transmission of sound as high as 250 Hz with a gradual cutoff by 400 Hz. The consolidated lung allowed transmission of sound of a higher frequency; however, there was no significant transmission of sound with a frequency higher than 1,000 Hz.

Auscultation↗
PubMedDate not supplied

"How am I doing?": many problems but few solutions related to feedback delivery in undergraduate psychiatry education.

OBJECTIVE: Giving performance feedback to students in psychiatry requires particular delicacy and skill since a critique of the subjective artistry of the psychiatric interview may be felt more personally than a critique of an objective skill, such as eliciting a reflex or applying a stethoscope to the chest. Thus, one would expect that psychiatrists 1) are adept at giving feedback and 2) have written about the nuances of feedback delivery in psychiatric education. After a curricular needs assessment in our program revealed that feedback delivery was being neglected at all levels of training, a review of the medical education literature was conducted to find explanations for preceptor difficulty with performance feedback delivery in undergraduate psychiatric education. METHOD: A qualitative content-analysis review of the PubMed and OVID literature on feedback delivery and medical education was conducted. RESULTS: Several articles were available on feedback delivery in medical education, but only one of the studies was specific to undergraduate psychiatric education. Several articles offered practical tips to address deficiencies in the feedback process, but there was little to no explanation for the reasons behind the deficiencies. CONCLUSIONS: Reasons for the challenges faced by medical students and teachers during feedback conversations have not been fully explored in the literature. In contrast to other areas of medicine, little has been written specifically about feedback to students in undergraduate psychiatric education. Although there are many resources to assist medical educators with feedback delivery skills, an understanding as to why physicians and students struggle with feedback conversations is needed. Reasons for the apparent disconnect between what should be happening and what is actually happening during feedback conversations with undergraduate psychiatry students need to be understood. The authors hypothesize causes for the problems with feedback delivery in undergraduate psychiatric education.

Achievement↗
PubMed1976

Phonocephalography extra-cephalic.

Phonocephalography is the amplification and recording of sounds from the surface and cavities of the head aiming for the introduction of a non-invasive pre-angiographic technique. Nasopharyngeal Phonocephalography was found successful for recording of normal tracing. The effect of the extra-cephalic sounds and factors on the tracing were discussed. Phonomyelography is the application of the idea on the vertebral column. The tracing recorded was demonstrated. Modern technology has undergone considerable progress for the introduction of non-invasive techniques in medical diagnosis. Since Laennec introduced his stethoscope auscultation, amplification and recording of sounds in cardiology had reached a respectable diagnostic procedure. This article represents a trial for the introduction of a simple non-invasive pre-angiographic diagnostic technique by amplification and recording of sounds from the surface and cavities of the body.

Auscultation↗
PubMed1979

A simple technique for measuring arterial blood pressures in conscious human subjects.

A new technique for measuring blood pressure utilizes the subject's ability to sense the onset and cessation of the Korotkoff phenomenon within the artery itself. Of the readings made in this manner with a standard arm cuff 94% were found to agree within +/- 10 mm Hg with readings made with a stethoscope. And 91% of the blood pressures measured by this technique using an infant cuff on the thumb were found to agree within +/- 10 mm Hg with those measured by the same technique with a standard cuff at the brachial artery. Therefore a simple device was designed with which subjects can measure their own systolic and diastolic blood pressure by utilizing a combined syringe and cuff applied to the thumb. There was a mean systolic difference of 4.7 and a mean diastolic difference of 6.1 mm Hg between readings made on 40 subjects with the new instrument and those made with a mercury sphygmomanometer.

Blood Pressure↗
PubMed1990

Effect of ischemia on ventricular contractility in patients with coronary artery disease.

The constant of elastance (E-MAX) is determined by measuring continuous left ventricular pressure and volume changes during the cardiac cycle. To evaluate the effect of myocardial ischemia on contractility, E-MAX was measured from serial pressure volume loops at baseline, with atrial pacing-induced ischemia, and after the administration of intravenous nitroglycerin with repeat pacing. Ten patients undergoing cardiac catheterization for presumed coronary artery disease were evaluated by this method. The severity of the coronary artery disease was graded angiographically by using the Gensini coronary score. In 8 of the 10 patients there was a significant decrease in E-MAX during atrial pacing (P less than .05). With the administration of nitroglycerin there was an attenuation of the ischemic effect previously noted with pacing. In 3 of the 10 patients administration of nitroglycerin produced a further decrease in E-MAX with ischemia. All 3 patients had a significantly lower Gensini coronary score with a well-developed, visible coronary collateral network. The authors' results indicate that continuous pressure volume loop analysis is possible using the nuclear stethoscope. Significant ischemic changes are seen with atrial pacing, which are relieved by the administration of nitroglycerin, except in the presence of coronary collaterals.

Cardiac Catheterization↗
PubMed2000

Prevention of accidental childhood strangulation. A clinical study.

Accidental strangulation is a preventable problem, and there is limited scientific understanding of its mechanism in children. If the amount of external pressure that occludes the airway can be determined, design changes may be made to allow for production of household objects that would break apart at safe pressure levels. A force gauge was applied to the suprahyoid region in 90 children under standardized anesthesia. Three blinded observers performed the study. The anesthesiologist maintained the airway and used a stethoscope to auscultate for breath sounds and monitor the CO2 curves to evaluate obstruction. The recorder noted the numbers from the gauge. A single observer applied the force gauge. Age was the most significant variable in occluding the airway. Obstruction appears to occur at the level of the larynx. Increased knowledge regarding the external pressure required for airway occlusion would allow for the design and manufacture of products with a reduced potential for accidental strangulation.

Accident Prevention↗
PubMed2002

Simple on-line endotracheal cuff pressure relief valve.

Ischemic injury of the tracheal mucosa in the endotracheally intubated patient is directly proportional to the tracheal tube cuff pressure. At a cuff pressure of 30 cm H2O, the tracheal mucosal blood flow becomes partially obstructed, and at a pressure of 45 cm H2O, the obstruction to the tracheal mucosal blood becomes total, leading to tracheal mucosal damage and subsequent complications. In our institute, we have developed a simple and very inexpensive method to gauge the cuff pressure. We use a regular 20-mL syringe attached in line with the connector of the endotracheal tube cuff. In this manner, we monitored the intracuff pressure in 120 patients who underwent ear or neck surgery. The syringe was connected to the tube cuff and inflated with 15 mL of air. The syringe was left constantly connected to the cuff. In addition, the cuff pressure was measured with the Mallinckrodt Hi-Lo aneroid pressure gauge at the beginning of surgery and hourly thereafter for the duration of surgery. At the same time, a check for leakage around the cuff was made by auscultation with a stethoscope above the sternal notch. Multiple comparisons between the repetitive intracuff pressure measurements revealed that there were no significant differences in the intracuff pressure values measured at the different times of surgery. These results indicate that there was an adequate venting of the excess intracuff pressure and also that there was no leakage around the cuff.

Adult↗
PubMed1982

Differential pulmonary auscultation in neonates.

Auscultation of neonates by means of conventional techniques is subject to many errors. Consequently, pediatricians rely on radiographs for much of their information regarding ventilation abnormalities. We report a method of simultaneous differential auscultation, using a double-headed stethoscope, which allows better auscultatory evaluation of neonates. The technique is simple and easily learned. The equipment used is inexpensive and easily constructed. The technique is most useful in emergency and transport situations when radiographs are not readily available.

Auscultation↗
PubMed1993

Power spectral analysis of temporomandibular joint sounds in asymptomatic subjects.

Very little has been done to quantify temporomandibular joint (TMJ) sound amplitudes and background noise and to determine the spectrum from healthy TMJs. Thus, the aim of this study was to record acoustically the sounds emitted by healthy TMJs with and without mandibular movements, for determination of baseline spectra. TMJ sounds were recorded bilaterally from 40 subjects with healthy joints by means of a self-developed recording system using miniature capacitor microphones inserted into the earpieces of a medical stethoscope placed in the meatus of the auditory canal. The recordings were performed without mandibular movements and during three consecutive opening and closing movements. The signals were high-pass-filtered at 50 Hz, low-pass-filtered at 2 kHz, and analyzed by fast Fourier transform computation on a 1024-point window (fs = 5 kHz). The linearly weighted average baseline spectrum recorded without motion showed maximum values of 31 dBSPL (sound pressure level) with a standard error of +2 to -3 dB. The linearly weighted average movement spectrum had a peak of 66 dBSPL at 156 Hz and decreased almost linearly by about 40 dB/decade to 25 dBSPL at 2000 Hz with a standard error of +/- 2 dB. Thus, the TMJ sound spectrum of mandibular movements in asymptomatic subjects differed at low frequencies by up to 35 dB from the baseline spectrum in absence of motion.

Adolescent↗
PubMed1987

Bicentenary of Sir John Forbes (1787-1861).

This year is the bicentenary of the birth of the distinguished Scottish physician, Sir John Forbes, famous for his translation of the great French medical classic, De L'Auscultation Médiate by R.T.H. Laennec, the inventor of the stethoscope.

Auscultation↗
PubMedDate not supplied

Bedside enteral feeding tube placement into duodenum and jejunum.

A bedside method for placement of nasoenteric feeding tubes is described utilizing gravity and corkscrewing of the feeding tube to pass the pylorus and then air injection to verify position of the tube from the location and character of transmitted sounds to the stethoscope. Twenty-eight of 31 consecutive patients requiring enteral feeding had tubes successfully placed past the pylorus using this method, 25 on the first attempt and three on the second. This method is an effective and inexpensive alternative to endoscopic or fluoroscopic feeding tube placement.

Duodenum↗
PubMed1985

Monitoring heart and breath sounds by telemetry.

A system for FM radiotelemetry of heart and breath sounds is described. Patients' heart and breath sounds are detected by oesophageal or precordial stethoscopes. The anaesthetist, carrying a portable radio receiver, is then free to move around theatre while listening to these sounds through headphones or an ear-piece. The FM telemetry system has also been used to assist patient monitoring in noisy environments such as ambulances.

Anesthesiology↗
PubMed1993

The Australian Incident Monitoring Study. Which monitor? An analysis of 2000 incident reports.

The role of monitors in patients undergoing general anaesthesia was studied by analysing the first 2000 incidents reported to the Australian Incident Monitoring Study; 1256 (63%) were considered applicable to this study. In 52% of these a monitor detected the incident first; oximetry (27%) and capnography (24%) detected over half of the monitor detected incidents, the electrocardiograph 19%, blood pressure monitors 12%, a low pressure (circuit) alarm 8%, and the oxygen analyser 4%. Of the other monitors used, 5 first detected 1-2% of incidents, and the remaining 8 less than 0.5% each. The oximeter would have detected over 40% of the monitor detected incidents had its more informative modulated pulse tone always been relied upon instead of the "bleep" of the ECG. A theoretical analysis was then carried out to determine which of an array of 17 monitors would reliably have detected each incident had each monitor been used on its own and had the incident been allowed to evolve. To facilitate "scoring" of monitors, the incidents were categorized empirically into 60 clinical situations; 40% of applicable incidents were accounted for by only 5 clinical situations, 60% by 10 and nearly 80% by 20. 98% were accounted for by the 60 situations. A pulse oximeter, used on its own, would theoretically have detected 82% of applicable incidents (nearly 60% before any potential for organ damage). These figures for capnography are 55% and 43% and for oximetry and capnography combined are 88% and 65%, respectively. With the addition of blood pressure monitoring these become 93% and 65%, and of an oxygen analyser, 95 and 67%. Other monitors, including the ECG, each increase the yield by by less than 0.5%. The international monitoring recommendations and those of the Australian and New Zealand College of Anaesthetists are thoroughly vindicated by the patterns revealed in this study. The priority sequence of monitor acquisition for those with limited resources should be stethoscope, sphygmomanometer, oxygen analyser if nitrous oxide is to be used, pulse oximeter, capnograph, high pressure alarm, and, if patients are to be mechanically ventilated, a low pressure alarm (or spirometer with alarm); an ECG, a defibrillator, a spirometer and a thermometer should be available.

Accidents↗
PubMed2002

Establishing a low-cost telemedicine link in far-eastern Russia.

A community-based primary care partnership was established between the University of Kentucky and the Central Hospital in Pereyaslavka, Russia. To assess community health needs, a community-initiated decision-making process was employed. As part of the primary care partnership, we conducted a telehealth pilot trial between a primary care hospital in Pereyaslavka and a tertiary care facility in Khabarovsk. Videoconferencing and the transmission of heart and lung sounds via telephone lines were successful within the Pereyaslavka Hospital. Videoconferencing was successful between the two hospitals (60 km apart) but the telephone lines were too noisy for the electronic stethoscopes. Telephone-based videoconferencing may prove to be important in helping rural medical practitioners in the Khabarovsk Territory to enhance the quality of health-care.

Community Health Services↗
PubMed2002

Carotid artery auscultation--anachronism or useful screening procedure?

Carotid bruits are supposed to indicate the presence of high-grade common carotid or extracranial internal carotid artery stenosis in a large proportion of patients. Using a stethoscope, we prospectively auscultated 273 carotid arteries of 145 patients blinded to the results of a complete extracranial and intracranial Doppler investigation including extracranial color-coded duplex ultrasound. Fifty-four arteries showed stenosis of > or = 50%-99%, or occlusion of the extracranial internal or the common carotid artery. In 25 of these arteries, a bruit was present. In 9 out of 16 patients with extracranial stenosis from 70%-99%, a bruit was detected. In one additional patient with a middle-grade external carotid artery stenosis, a bruit was also present. In seven additional patients, a bruit was present in the absence of any carotid artery stenosis, cardiac vitium or goiter. The sensitivity of carotid auscultation for the detection of a 70%-99% stenosis of the common or extracranial internal carotid artery was 56% and specificity was 91%. The positive predictive value of a bruit found during carotid auscultation was 27%, and the negative predictive value of a normal auscultation was 97%. Carotid auscultation is a useful screening procedure in the detection of carotid stenosis or occlusion, but requires confirmation by carotid ultrasound.

Adult↗
PubMed2006

Inaudible temporomandibular joint vibrations.

The aim was to test the hypothesis that inaudible vibrations with significant amounts of energy increasing during jaw movements can be recorded in the temporomandibular joint (TMJ) area. Twenty one subjects, who could perform wide opening movements without feeling discomfort, 12 with and 9 without TMJ sounds audible at conventional auscultation with a stethoscope, were included. Recordings were made during opening-closing, 2/s without tooth contact, and during mandibular rest, using accelerometers with a flat frequency response between the filter cutoff frequencies 0.1 Hz and 1000 Hz. The signals were digitized using a 24 bits card and sampled with the rate 96000 Hz. Power spectral analyses, and independent and paired samples t-tests were used in the analysis of the vibration power observed in frequency bands corresponding to audible and inaudible frequencies. An alpha-level of 5% was chosen for accepting a difference as being significant. In the group with audible sounds, about 47% of the total vibration energy was in the inaudible area below 20 Hz during opening-closing and about 76% during mandibular rest. In the group without audible sounds, the corresponding proportions were significantly different, 85% vs. 69%. The energy content of the vibrations, both those below and those above 20 Hz, increased significantly during jaw movement in both groups. Furthermore, percentage of signal energy above 20 Hz showed a noticeable increase in the group of subjects with audible sounds. This can physically be explained by decreased damping properties of damaged tissues surrounding the TMJ. Vibrations in the TMJ area can be observed with significant portions in the inaudible area below 20 Hz both during mandibular rest and during jaw movements whether or not the subjects have audible joint sounds. Further studies are needed to identify sources and evaluate possible diagnostic value.

Adult↗