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At least 19 recordsLinked to original sources
PubMed1986

An electronic stethoscope is judged better than conventional stethoscopes for anesthesia monitoring.

A prototype electronic monitoring stethoscope was constructed from readily available, high-quality components. It consisted of a conventional precordial or esophageal probe connected to a microphone by a rubber adapter. The microphone was connected by lightweight wire to an amplifier and headphones. Twenty-one anesthesia clinicians evaluated the stethoscope and responded to a multiple-choice preference questionnaire. The electronic stethoscope was judged to perform better than the conventional stethoscope in most categories evaluated. The electronic device was perceived to be louder, clearer in sound reproduction, more efficacious for monitoring, and easier to use continuously, and its headphones were considered more comfortable than the conventional earpiece. Based on our results, we conclude that amplified stethoscopes have the potential to improve monitoring. Further development of electronic stethoscope monitoring seems warranted and is continuing.

Anesthesia↗
PubMedDate not supplied

[Comparison of auscultation findings using a classic stethoscope (Litmann 2120) and electronically amplified stethoscope (Medmax2)].

Heart auscultation has one of the key roles in beside diagnosis, especially in patients with cardiovascular diseases. Sometimes, because of the human cars' low sensitivity, a problem emerges in the proper evaluation of heart sounds and murmurs of lower frequencies. Our study compared two stethoscopes, the classic acoustic stethoscope (Littmann 2120) and an electronic one with the sound amplifier and the noise filtering system (Medmax2) in 10 patients examined by 10 physicians. Significantly better detection of low frequency sounds was found in favour of electronic stethoscope (chi 2 = 17.9; p < 0.0001). It is concluded that the selective amplificator improves the stethoscope performance and has its place in everyday bedside practice, especially in departments of cardiology.

Aged↗
PubMed1997

The stethoscope. A potential source of nosocomial infection?

BACKGROUND: Stethoscope diaphragms have been shown to harbor potentially pathogenic bacteria. OBJECTIVES: To assess bacterial contamination on the diaphragm and under the plastic rim that secures the diaphragm of stethoscopes of physicians, nurses, medical students, and house staff in an intensive care unit and a general medical ward of a large university hospital. Also to compare the effectiveness of various cleaning agents and assess the transmissibility of bacteria from contaminated stethoscopes to human skin. METHODS: Aerobic and anaerobic bacterial cultures were performed on 40 randomly selected stethoscopes. We compared the effects of isopropyl alcohol, sodium hypochlorite (bleach), and benzalkonium chloride swabs, as well as soap and water, on reducing bacterial contamination on the stethoscope diaphragm and under the rim. The transmissibility of Micrococcus luteus inoculated onto a stethoscope diaphragm to clean human skin was also determined. RESULTS: Eleven genera and species of bacteria were isolated, with coagulase-negative staphylococcus present on 100% of stethoscopes and Staphylococcus aureus on 38%. Clostridium difficile was not isolated. The mean (+/-SE) number of total colony-forming units was 158 +/- 33 per diaphragm and 289 +/- 54 per rim. Physicians' stethoscope diaphragms had significantly more colony-forming units of coagulase-negative staphylococci than those of nurses: 163 +/- 44 vs 50 +/- 12, respectively (P = .02). The most effective cleaning agent was isopropyl alcohol after cleaning the diaphragm surface, the stethoscope diaphragms contained 0.2 +/- 0.2 colony-forming units and the rims contained 2.2 +/- 1.5 colony-forming units (P = .01). In addition, M luteus was transferred from inoculated stethoscopes to human skin. CONCLUSIONS: Most stethoscopes harbor potential pathogens but are not a source of C difficile. Physicians' stethoscopes generally had a higher bacterial load than nurses' stethoscopes. Isopropyl alcohol is an effective cleaning agent when applied to the stethoscope diaphragm. Stethoscopes transfer M luteus to human skin, making it likely that other bacteria can be transferred as well.

Cross Infection↗
PubMed1996

Contaminated stethoscopes revisited.

BACKGROUND: Because of their universal use by medical professionals, stethoscopes can be a source of nosocomial infections. OBJECTIVE: To determine the frequency of contamination of stethoscopes with bacteria and fungi. METHODS: Cultures were obtained from 200 stethoscopes from four area hospitals and outpatient clinics in Houston, Tex. The frequency of stethoscope contamination in different groups of hospital personnel and medical settings was determined. We also measured the frequency of antimicrobial resistance of the staphylococcal strains that were isolated. RESULTS: One hundred fifty-nine (80%) of the 200 stethoscopes surveyed were contaminated with microorganisms. The majority of organisms that were isolated were gram-positive bacteria, primarily Staphylococcus species. Fifty-eight percent of the Staphylococcus species that were isolated, including four (17%) of 24 Staphylococcus aureus isolates, were resistant to methicillin. Physicians' stethoscopes were contaminated more often than those of other medical personnel groups (P = .02). Stethoscopes used only in designated areas were contaminated less frequently than stethoscopes belonging to individual medical personnel (P = .01). Although stethoscopes were contaminated in all areas, stethoscopes from the pediatric medical setting were contaminated less frequently than those from other hospital areas (P = .009). CONCLUSIONS: Stethoscope use may be important in the spread of infectious agents, including antimicrobial-resistant strains, and strategies to reduce the contamination of stethoscopes should be developed. We recommend disinfection of stethoscopes or regular use of disposable stethoscope covers.

Auscultation↗
PubMedDate not supplied

Organic buildup and residual blood on infant stethoscopes in maternal-infant areas.

OBJECTIVE: To identify the presence of residual blood and organic matter on "clean" stethoscopes in maternal-infant units. DESIGN: In this retrospective, nonexperimental study, stethoscopes were tested using qualitative measurements. SETTING: Using a nonprobability sampling technique, 11 acute care hospitals in a three-state area of the southwestern United States were studied. PARTICIPANTS: All stethoscopes found on the maternal-infant units were included, for a total sample size of 97. INSTRUMENTS: A hand-held 10-power lens was used to visually rank the amount of organic buildup, and the phenolphthalein test was used to detect residual blood on the stethoscope. RESULTS: Of 97 clean infant stethoscopes, 80% of labor and delivery and 72% of nursery stethoscopes had organic buildup on the diaphragm. Both areas had similar rates of organic buildup, chi2 (1, N = 97) = 1.00, p = ns. Nursery areas did have significantly lower rates of residual blood than stethoscopes from labor and delivery, phi2 (1, N = 97) = 9.89, p = .002. Seventy-six percent of labor and delivery stethoscopes were positive for blood, as compared to 46% of nursery stethoscopes. CONCLUSIONS: Traditional methods for cleaning stethoscopes used in labor and delivery and nursery areas are ineffective in removing blood and other body fluids from the stethoscope.

Antisepsis↗
PubMed1990

Observer reliability in detecting surreptitious random occlusions of the monaural esophageal stethoscope.

The esophageal stethoscope is used often during anesthesia to monitor ventilation and cardiac function. Deficiencies in observer vigilance may limit the effectiveness of this monitoring instrument. The aim of this study was to determine how long it took for an observer to detect a surreptitiously occluded monaural esophageal stethoscope in the setting of clinical anesthesia. During routine anesthesia, where an esophageal stethoscope was in use, a computer-guided device would artificially, silently, and at random time intervals, occlude the stethoscope tubing. Personnel using the stethoscope noted when they perceived the absence of stethoscope sounds. We studied 320 stethoscope occlusions in 32 patients. The time between stethoscope occlusion and detection was 34 +/- 59 seconds (mean +/- SD). Eighty-seven percent of detections were made in less than 60 seconds. However, 13% of detections were delayed for more than 60 seconds, and 2.3% for more than 240 seconds. While anesthesia personnel using an esophageal stethoscope could detect most stethoscope occlusions, failure to appreciate such episodes occurred in a small but significant number of cases. This suggests that the esophageal stethoscope has some definite limitations as a continuous monitor and that other monitoring techniques, such as oximetry, capnography, and ventilator disconnect alarms, as well as visual/tactile inspection of the patient, should be used as well.

Anesthesia, General↗
PubMed1995

Use of esophageal or precordial stethoscopes by anesthesia providers: are we listening to our patients?

STUDY OBJECTIVE: To ascertain current anesthesia utilization of esophageal and precordial stethoscopes in U.S. anesthesia training programs. DESIGN: Prospective, single-blind, incidence study. SETTING: Operating rooms of three tertiary care hospitals with major academic anesthesiology departments. SUBJECTS: Anesthesia faculty [MD and certified registered nurse-anesthetist (CRNA) staff] and anesthesia trainees (anesthesiology residents and student nurse-anesthetists). INTERVENTIONS: observe and record the placement (stethoscope device appropriately positioned) and utilization (stethoscope in place and connected to the ear piece of the anesthesia provider) of the esophageal or precordial stethoscope during general, regional, and monitored anesthesia care. MEASUREMENTS AND MAIN RESULTS: During 520 anesthetics, an esophageal stethoscope was inserted in 68% of subjects, a precordial stethoscope was positioned in 16%, and an anesthetic stethoscope was absent in 16% of cases. Utilization (stethoscope connected to earpiece) ranged from a low of 11% of cases to a high of 45%, depending on the institution. Overall, providers were listening via an anesthetic stethoscope in only 28% of anesthetics. CONCLUSIONS: Our data suggest infrequent utilization of esophageal and precordial stethoscopes in anesthesia training institutions. Thus, current anesthesia training may be fostering an environment where providers overlook a valuable minimally invasive, and cost-effective continuous monitor of patients' dynamic vital organ function.

Anesthesia Department, Hospital↗
PubMed1995

Stethoscopes: a potential vector of infection?

STUDY OBJECTIVES: To survey emergency care providers about their stethoscope-cleaning measures and to determine the correlation between these measures and the extent of Staphylococcus carriage. DESIGN: Prospective cross-sectional analysis. SETTING: University-affiliated community hospital ED. PARTICIPANTS: One hundred fifty health care providers, comprising emergency medicine house staff and attending physicians (n = 50), ED nurses (n = 50), and prehospital personnel working in Kent County, Michigan (n = 50). INTERVENTIONS: Providers were asked how often they cleaned their stethoscopes and which cleaning agents were used. We then cultured each stethoscope by pressing the diaphragm on mannitol agar and incubating the culture aerobically for 48 hours. Staphylococcus aureus was identified by means of standard measures. We examined the effects of different cleaning agents on 24 stethoscopes. The numbers of colony-forming units (CFUs) before and after cleaning with alcohol, nonionic detergent, and antiseptic soap were noted. RESULTS: Overall, 48% of health care providers (74 of 150) cleaned their stethoscopes daily or weekly, 37% monthly, and 7% yearly; and 7% had never cleaned their stethoscopes. No significant differences were found in the hygiene routines of the three groups of providers surveyed. Use of an alcohol swab was the preferred method of cleaning. One hundred thirty-three stethoscopes (89%) grew staphylococci; 25 (19%) yielded S aureus. Mean staphylococcal bacterial counts ( +/- SD) were 52 +/- 78 CFUs per stethoscope among physicians, 46 +/- 92 CFUs among emergency medical service personnel, and 13 +/- 21 CFUs from the nursing staff (ANOVA, P = .01). Cleaning the stethoscope diaphragm resulted in immediate reduction in the bacterial count: by 94% with alcohol swabs, 90% with nonionic detergent, and 75% with antiseptic soap. CONCLUSION: Our results confirm that stethoscopes used in emergency practice are often contaminated with staphylococci and are therefore a potential vector of infection. This contamination is greatly reduced by frequent cleaning with alcohol or nonionic detergent.

Auscultation↗
PubMed1997

Stethoscopes and otoscopes--a potential vector of infection?

OBJECTIVES: We aimed to determine whether stethoscopes and otoscopes used in community paediatric clinics harboured pathogenic micro-organisms, and, if so, which measures could prevent this. METHODS: Fifty-five stethoscopes belonging to paediatric physicians working in 12 community clinics were sampled for bacterial cultures by two methods: (i) direct impression of the diaphragm and bell section of each stethoscope for 5 seconds onto blood agar plates and a mannitol-salt-agar plate; (ii) swabbing the entire surface of the diaphragm of the stethoscope with a sterile cotton-tipped applicator. Forty-two otoscopes from the same physicians were sampled by rubbing the handles of the otoscopes with cotton-tipped swabs. The plates were incubated at 37 degrees C for 48 hours and examined for colony growth at 24 and 48 hours of incubation. Culture results were recorded as mean numbers of colony-forming units (CFUs). Eight additional stethoscope diaphragms were chosen at random at the participating clinics and cultured as described above. They were then wiped with alcohol swabs (isopropyl alcohol 70%), allowed to air dry for approximately 10 minutes and cultured a second time. RESULTS: All the stethoscopes and 90% of the otoscope handles were colonized by microorganisms. Staphylococci were isolated from 85.4% of the stethoscopes and 83.3% of the otoscopes, with 54.5% and 45.2% respectively being S. Aureus. Methicillin-resistant S. aureus were found in four each of the stethoscopes (7.3%) and otoscopes (9.5%). Cleaning with alcohol reduced the colony count by an average of 96.3%. CONCLUSIONS: Fomites can harbour potentially pathogenic bacteria, and with the increasing trend for children with more complex medical problems to be managed in an ambulatory setting, often by physicians who also work in hospitals, there is a real risk of spreading potentially serious infections to such patients. Simple cleansing with alcohol effectively eliminates the bacterial contamination of the fomites, and should be encouraged.

Community Health Centers↗
PubMed1995

[Frequency analysis of crackles recorded with a stethoscope-equipped recorder].

Crackles were recorded with one of two systems in a total of 58 cases and compared. In one system a stethoscope was attached to a microphone; in the other system no stethoscope was used (see reference 9). Coarse crackles were recorded with the stethoscope system in 11 patients, and with the microphone-only system in 12 patients. Most patients with coarse crackles had bronchiectasis. Fine crackles were recorded with the stethoscope system in 13 patients, and with the microphone-only system in 22 patients. Most patients with fine crackles had idiopathic pulmonary fibrosis. Each record was examined visually, and all crackles recorded during one inspiration were selected. Power spectra were estimated with the maximum entropy method and peak frequencies were determined with the damped least-squares method. Type-I crackles were defined as those with all peak frequencies below 800 Hz; these low-pitched sounds may correspond to coarse crackles. Type-II crackles were defined as those with peak frequencies over 800 Hz regardless of the existence of peaks below 800 Hz; these high-pitched sound may correspond to fine crackles. The "%Type II" was defined as the percentage of the total crackles that were Type-II crackles. The %Type II value among coarse crackles was 10 +/- 16% with the stethoscope and 3 +/- 7% with the microphone. Among fine crackles, the values were 65 +/- 22% with the stethoscope and 79 +/- 23% with the microphone. For both kinds of equipment, the %Type II differed significantly between coarse and fine crackles (p < 0.01). The stethoscope-transmitted sound had components that could be used to differentiate fine crackles from coarse crackles. For clinical purposes, crackles recorded with a stethoscope are as useful as those recorded with a microphone only.

Auscultation↗
PubMed1985

Accuracy of left ventricular ejection fraction using the nuclear stethoscope in left ventricular aneurysm.

Although the nuclear stethoscope, a nonimaging probe, accurately determines left ventricular (LV) ejection fraction (EF), its reliability in patients with LV aneurysm has not been established. Accordingly, LVEF was determined using the nuclear stethoscope and compared with that determined by equilibrium gated blood pool scanning in 29 patients, 1 studied on 2 separate occasions, for a total of 30 patient studies. Patient studies were separated into 2 groups. Patients in group I (n = 20) had no gated blood pool evidence for aneurysm, and those in group II (n = 10) had discrete focal akinesia or dyskinesia. Nineteen patients (13 in group I and 6 in group II) had 2 separate nuclear stethoscope acquisitions. In group I, EF determined by gated blood pool scanning (53 +/- 4%, mean +/- standard error) did not differ from that determined by nuclear stethoscope (51 +/- 4%). EF determined using either gated blood pool scanning (32 +/- 6%) or nuclear stethoscope (35 +/- 5%) was significantly lower in group II than in group I, although nuclear stethoscope and gated blood pool scanning did not differ. Reproducibility was excellent (r = 0.96). Overall, nuclear stethoscope and gated blood pool EFs correlated closely (r = 0.93), and the correlation coefficients were similar in groups I (r = 0.92) and II (r = 0.92). The slopes of the regression curves for group I (0.97) and group II (0.92) were not statistically different. These results confirm the accuracy and reproducibility of LVEF determination by nuclear stethoscope and specifically demonstrate its reliability in patients with LV aneurysm.

Adult↗
PubMedDate not supplied

Use of the esophageal stethoscope in pediatric transports.

INTRODUCTION: Monitoring cardiac and respiratory function during helicopter transports can be difficult, so the authors devised a study of the esophageal stethoscope for pediatric patients. SETTING: The study was conducted at Pediflite in Tennessee, which transports between 250 to 300 pediatric patients every year. MATERIALS AND METHODS: A disposable esophageal stethoscope was used as an adjunct to other monitoring systems in intubated patients. Prior to transport, the stethoscope was placed orally by the respiratory therapist and advanced to the point where heart sounds are heard best, at which point breath sounds can also be heard clearly. The device's ear piece easily fit under the crew member's headphones, which block helicopter noise. Three sizes of stethoscope are available: a 6 French for patients 1 day to 4 years old, a 9 French for those 4 to 12 years old, and an 18 French for patients 12 years of age or older. RESULTS: The esophageal stethoscope was used in 55 patients ranging in age from newborn to 18 years. Eighteen of 55 (33%) had multiple trauma or closed head injury, and 14 of 55 (25%) suffered respiratory failure. The esophageal stethoscope proved to be easy to place, had a low risk of complications and allowed continuous access to breath sounds. In addition, the ability to hear heart tones was minimally affected by noise or vibration. CONCLUSION: Due to its ability to continuously monitor breath sounds, endotracheal tube obstruction or displacement can be rapidly detected by the esophageal stethoscope. Also, if there is failure of the cardiopulmonary monitor, heart sounds can be continuously monitored. The esophageal stethoscope is a simple but potentially valuable tool in pediatric and neonatal transports for monitoring respiratory and cardiac status.

Adolescent↗
PubMed1986

[Reliability of the ejection fraction determined with the nuclear stethoscope. Comparison with angiocardiography].

The purpose of this investigation was to compare the Ejection Fraction values simultaneously obtained with the Nuclear Stethoscope and with Cineangiography, in 25 patients (17M-8W) subjected to diagnostic cardiac catheterization. In all patients the determination of Ejection Fraction with the Nuclear Stethoscope always preceded the Cineangiography. Ejection Fraction values obtained with Nuclear Stethoscope change from 32 to 75%; those calculated with Cineangiography, between 18 and 88%. The average Ejection Fraction values obtained with Nuclear Stethoscope (59 +/- 13%) doesn't differ significantly from Cineangiography (59 +/- 21%). There was a direct relationship between Ejection Fraction determined by the Nuclear Stethoscope and Cineangiography (r = 0.93; p less than 0.001). In the obtained results the Authors point out that the Ejection Fraction with Nuclear Stethoscope gives assurance in most patients, although in some particular conditions Nuclear Stethoscope provides Ejection Fraction values which differ from those obtained with Cineangiography. They conclude that Nuclear Stethoscope, for its safe, repeating and simple application, is a methodology of useful employment for Ejection Fraction determination in the single patient, which allows a correct definition of the prognosis and a conforming therapeutic strategy.

Adolescent↗
PubMed1993

The Australian Incident Monitoring Study. The stethoscope: applications and limitations--an analysis of 2000 incident reports.

The first 2000 incidents reported to the Australian Incident Monitoring Study (AIMS) were analysed with respect to the role of the oesophageal or precordial stethoscope as a continuous monitor. There were 1099 of the 1256 incidents during general anaesthesia in which one might have been used in this way, but use was reported in only 65 cases (5%), predominantly during paediatric cases. In only one report, a cardiac arrest, was the stethoscope the first to detect the incident. In a theoretical analysis it was considered that the stethoscope, used on its own for continuous monitoring, could have detected 54% of the 1256 incidents (almost 25% before any potential for organ damage), had they been allowed to evolve. However, AIMS data suggest that the actual yield using a stethoscope as a continuous monitor may be much lower than this, and that even the use of a "mobile" stethoscope can not be relied upon to detect oesophageal or endobronchial intubation. These reports confirm that there is limited use of the stethoscope for continuous monitoring in current anaesthetic practice in Australia; it has been superseded by the sophisticated electronic monitors now available. However, in areas with limited resources continuous auscultation with a stethoscope remains a basic requirement.

Accidents↗
PubMed1996

[Level of stethoscope contamination in the hospital environment].

The aim of this study was to determine the extent of the contamination of stethoscopes and their possible role in transmission of microorganisms. The stethoscopes of the medical doctors of the hospital of La Chaux-de-Fonds, Switzerland, were cultured and the date of the last cleaning recorded. 38 of the 62 stethoscopes surveyed were contaminated with microorganisms (61%). The majority of isolated organisms were gram-positive bacteria, primarily Staphylococcus species (89%). The cleaning of the stethoscopes was frequent for 32% of the doctors, rare for 46% and non-existent for 22%. After more than one day without cleaning of the stethoscope, the level of contamination rose from 0% to 69%. Stethoscope use may be an important factor in the spread of infectious agents, so that regular disinfection should be carried out (once a day at the very least).

Bacteriological Techniques↗