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At least 775 records · Page 43Linked to original sources
PubMed1993

The acute response of left ventricular filling dynamics to intravenous verapamil predicts the changes in exercise tolerance after oral verapamil therapy in patients with hypertrophic cardiomyopathy.

We studied the correlation between changes in left ventricular filling dynamics induced by acute intravenous administration of verapamil and the changes in exercise tolerance induced by oral administration of the agent in 30 patients with hypertrophic cardiomyopathy. Diastolic cardiac function was measured by means of a nuclear stethoscope before and 10 min after intravenous administration of verapamil, 0.15 mg.kg-1 over 2 min. Treadmill exercise tests using a modified Bruce protocol were performed before the initiation of oral verapamil treatment and after 4 weeks of oral therapy at a dose of 320-360 mg.day-1 (mean +/- SD 332 +/- 17 mg.day-1). Peak filling rate (PFR) increased in 21 patients, 18 of whom (86%) also had an increase in exercise duration, PFR showed no increase in nine patients, eight of whom (89%) had no change in exercise duration (sensitivity 95%, specificity 73%, predictive value of the positive result 86%, predictive value of the negative result 89%). Acute changes in time from the beginning of rapid filling to PFR (t-PFR) and in left ventricular end-diastolic volume (EDV) were less useful in predicting improvement in exercise tolerance. In 19 patients the changes in PFR and EDV paralleled. Twelve of the 13 patients (92%) with an increase in both parameters also had an increase in exercise duration, whereas all six in whom these parameters were reduced showed no increase in exercise duration (sensitivity 100%, specificity 86%, predictive value of positive results 92%, and predictive value of negative results 100%).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

Ambulatory scintigraphic assessment of transient changes in left ventricular function: a new method for detection of silent myocardial ischaemia.

Demonstration of ischaemic left ventricular dysfunction in the absence of chest pain should provide important confirmation of silent myocardial ischaemia in patients with asymptomatic ST segment changes. For this purpose, a new portable scintillation probe (VEST) similar to a miniaturized nuclear stethoscope combined with a Holter ECG was evaluated. After standard equilibrium radionuclide angiocardiography with technetium-99m labelled red blood cells, the VEST was positioned under gamma-camera control and data were recorded from 1-12 h in 61 unselected patients. Ejection fraction (LVEF), relative changes in volumes, heart rate and ST segment changes were determined. Reproducibility of LVEF at rest (r = 0.91; variability 3.8 +/- 3%, N = 19) and during exercise (r = 0.98; variability 3.2 +/- 2%, N = 19) was good. In 15 asymptomatic exercise tests four different patterns of LVEF and ST segment responses were identified: (1) decrease in LVEF followed by significant ST depression (five times); (2) ST depression followed by decrease in LVEF (three times); (3) decrease in LVEF without significant ST changes (three times); and (4) ST depression without significant LVEF change (four times). In this still small series, patterns (1) to (3) corresponded to patients with documented coronary artery disease, which was not the case for pattern (4). For detection of silent ischaemia at rest, a decrease in LVEF of greater than 5% lasting for greater than 1 min was defined as ischaemic LV dysfunction. Using this definition, four spontaneous episodes of silent LV dysfunction could be demonstrated in two of three CCU patients with unstable angina during 160-680 min of data recordings without simultaneous ST changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1984

Measured differences between fourth and fifth phase diastolic blood pressures in 4885 adults: implications for blood pressure surveys.

To examine in detail the relationship between fourth (D4) and fifth (D5) phase diastolic blood pressures, we used data from risk factor surveys of 4885 adults. Observers were carefully trained using audio tapes and double-stethoscope exams to record the onset of the first, fourth (muffling), and fifth (disappearance) phases of Korotkoff sounds with random-zero sphygmomanometers. The expected size of the difference between D4 and D5 pressures (D4-D5) was not discussed with observers. D4-D5 was greater (mean +/- SEM) in men (2.4 +/- 0.1 mmHg) than in women (1.9 +/- 0.1 mmHg), but two thirds of D4-D5s were not measurable, that is, 0 mmHg. Larger D4-D5s were associated with higher systolic and D4 levels, lower D5 levels, and younger ages. D4-D5 varied markedly among observers. Approximately 58% of D4-D5s exceeding 10 mmHg occurred among six observers who measured 16% of the blood pressures. However, generally the difference between D4 and D5 measured by our observers and methods was smaller than commonly believed. The possible reasons for this are discussed. We recommend that epidemiological studies measure and report both diastolic readings (D4 and D5) so that their interrelationship may be studied further in other populations.

Adult↗
PubMed1981

A comparison of the Sphygmetrics SR-2 Automatic Blood Pressure Recorder to the mercury sphygmomanometer in population studies.

The Sphygmetrics SR-2 Automatic Blood Pressure Recorder uses an infrasonic technique for detecting artery wall motion to estimate systemic arterial pressure and produces a permanent record of the results. It therefore is potentially useful in reducing observer bias in epidemiologic studies of blood pressure (BP). Two blood pressures were recorded in 21 men and 50 women using the SR-2 simultaneously with two auscultators using a biaural stethoscope and mercury syhgmomanometer. The SR-2 measured slightly higher systolic nd slightly lower diastolic pressures on average, but the differences were not significant. The two auscultators were highly correlated with one another (r = 0.99 systolic/0.97 diastolic) and with the SR-2 (0.93 and 0.92 for systolic, 0.84 and 0.85 for diastolic). The correlations were unrelated to sex, age, or antihypertensive medication status, but the correlations between th SR-2 and either auscultator for diastolic BP were quite low (0.36, 0.55) in subjects whose relative weight was below 1.0. Interpretation of the SR-2 disc was very reliable, with inter- and intra-reader correlations being 0.99 for systolic and 0.84 to 0.94 for diastolic. The SR-2 was found to be comparable to auscultation in estimating systolic BP in a heterogeneous population which has the advantages of reducing observer bias and producing a permanent record. Its use in estimating diastolic pressure in thin individuals and children needs further evaluation.

Adult↗
PubMed1982

Resting heart rate and pressure-rate product of children in a total biracial community: the Bogalusa Heart Study.

Resting heart rates were ascertained during the 1978-1979 school year in 3590 children aged 5-17 years in the biracial geographic population of Bogalusa, Louisiana. These rates were found to be relatively independent of the method of measurement, whether supine by physician's stethoscope or dressed sitting radial pulse taken by a nurse, and in either case adhering to a strict measurement protocol. Apart from the known influences of age and sex, the authors found a small but consistent racial influence, with whites having 3-4 beats/min higher rates than blacks. Controlling for age, the authors found heart rate to be positively correlated with blood pressure in whites and with subcapsular skinfold thickness in boys. No consistent relation between heart rate and amount of cigarettes smoked was observed. Boys in the upper five percentiles of blood pressure-heart rate ("double") product values were found to have about twice the subscapular skinfold thickness compared to the lower five percentiles. Likewise, boys in the upper five percentiles of subscapular skinfold thickness had significantly increased double products. Since the double product is an index of cardiac oxygen consumption, this finding could point to a possible etiologic link between obesity and chronic cardiac stress in males beyond the mediation of lipoproteins, cholesterol, and diabetes mellitus in contributing to atherosclerotic heart disease, but this issue needs further study. Ascertainment of resting heart rate provides an additional parameter in the study of cardiovascular risk factor variables, in youth as in adulthood, to supplement the natural history of the atherosclerosis-hypertension syndrome with its sequelae.

Adolescent↗
PubMed1985

The random-zero versus the standard mercury sphygmomanometer: a systematic blood pressure difference.

The random-zero and standard mercury sphygmomanometers are used frequently, and sometimes interchangeably, in epidemiologic studies. To determine whether there is a systematic difference between them, the authors measured systolic, fourth-phase, and fifth-phase diastolic blood pressures using both sphygmomanometers simultaneously in a series of six experiments. For most experiments, the system for simultaneous blood pressure measurements employed one cuff connected to both sphygmomanometers, which were carefully calibrated and read by two trained technicians using a double stethoscope. Order of use of the random-zero sphygmomanometer was randomly assigned, and technicians were blind to each others readings. At deflation rates of 2 mmHg/second, readings of the random-zero sphygmomanometer were systematically lower than those of the standard mercury sphygmomanometer: -0.9 mmHg for systolic, -1.8 mmHg for fourth-phase, and -1.8 mmHg for fifth-phase diastolic blood pressures (all differences, p less than 0.001). The difference persisted after adjustment for subject age, sex, heart rate, blood pressure level, observer, and room temperature, and was present for varying deflation rates. However, by draining the residual mercury from a random-zero sphygmomanometer and using the instrument as if it were a standard mercury sphygmomanometer, much of the difference between the two was eliminated. This suggests that the mechanism for the difference relates to the increased height of mercury in the random-zero manometer tube. The authors conclude that the random-zero and standard mercury sphygmomanometers should not be used interchangeably in epidemiologic studies.

Adult↗
PubMed1995

Interrater reliability of auscultation of breath sounds among physical therapists.

BACKGROUND AND PURPOSE: Although auscultation is routinely used in the assessment of respiratory status, the ability of the rater to accurately and consistently identify lung sounds has been questioned. The literature on this issue is sparse and has focused on reliability of auscultation of tape-recorded rather than in vivo lung sounds. The purposes of this study were to determine the interrater reliability of physical therapists in the direct auscultation of lung sounds based on their clinical experience in chest physical therapy and to determine whether the adoption of standardized nomenclature and education on proper technique and interpretation affects reliability. SUBJECTS AND METHODS: A group of 57 registered physical therapists were stratified by clinical experience into four groups. Sixteen therapists (ie, 4 in each stratum) were randomly chosen using a random number table. The following criteria were developed to delineate clinical experience. Group 1 subjects were senior chest physical therapists with at least 5 years of experience in this area of practice. Group 2 subjects were experienced therapists who had a minimum of 2 years of experience in chest physical therapy and were currently practicing in this area. Group 3 subjects were experienced physical therapists in other areas who were also practicing in chest physical therapy on occasional weekend service. Group 4 subjects were new graduates. Ten patients were evaluated by each group of 4 physical therapists using a teaching stethoscope with one diaphragm/bell and four pairs of earpieces. The education session consisted of discussion of the adoption of standardized nomenclature and education on proper technique and interpretation of auscultation. Interrater reliability was assessed before and after the education session using kappa (kappa) values. Comparisons were made between kappa values before and after the education session to determine the effect of education and between groups to determine the effect of clinical experience. RESULTS: The kappa values before the education session were low, indicating poor reliability in detecting specific abnormal sounds (kappa = -.02-.59). Group 1 (seniors in respiratory therapy) and group 4 (new graduates) demonstrated the greatest reliability levels. The lowest kappa values were observed for detecting and categorizing the quality of breath sounds (normal, absent, bronchial, or decreased) (kappa = -.02-.25). Following the education session, there was a general improvement in reliability (kappa = -.30-.77), especially for group 3 (specialists in other areas). The most improvement was noted for the detection of the quality of breath sounds (kappa = .08-.50). CONCLUSION AND DISCUSSION: Reliability of auscultation was poor to fair, in general, before the education session. There was a definite improvement in reliability after the education session. There was no clear effect of clinical experience on reliability, and the agreement among observers appeared to depend on the abnormal lung sound present. Limitations of this study and recommendations for future research are discussed. [Brooks D, Thomas J. Interrater reliability of auscultation of breath sounds among physical therapists.

Auscultation↗
PubMed1999

History of medicine: the metamorphosis of scientific medicine in the ever-present past.

Hippocrates (460-370 BCE), the father of medicine, developed principles for medical diagnosis and treatment together with a code of ethics. When the first Ptolemy ruled Egypt, he created a great library of 700,000 rolls at Alexandria, which became a repository for the works of Socrates, Plato, Aristotle, Hippocrates, and all the writings of the known world, but it was destroyed by a great fire. Galen of Pergamum (129-216), who lived 500 years after Hippocrates, was well educated and studied anatomy, surgery, drugs and Hippocratic medicine. His ideas influenced medical thinking for the next 1500 years. The Arabic physician Ibn Sina (Avicenna) wrote a great medical work entitled Canon of Medicine. After the Dark Ages (500 to 1050), academic medicine was reestablished in Europe, especially at Salerno, Bologna, Padua, Paris, Montpellier, and Oxford. The greatest medical disaster of the Middle Ages was the Black Death. Other diseases of note were leprosy, smallpox, tuberculosis, typhus, measles, diarrhea, meningitis, and colic. As interest in human dissection increased, the study of anatomy became popular. With development of the printing press, medical knowledge became more widely disseminated and technical advances in science flourished. Advances in medicine occurred in concert with developments in technology. These included the microscope, the stethoscope, anesthetic agents, discoveries in bacteriology, a carbolic acid spray to reduce infection during surgery, the clinical thermometer, blood transfusions, electrocardiography, X-rays, and the sphygmomanometer. Johns Hopkins University was established at the end of the 19th century to train scientifically knowledgeable physicians. The first faculty included Welch, Osler, Halstead, Kelly, Mall, and Abel. Graduates of the new school carried scientific medicine to universities throughout America. More medical advances have been made during the 20th century than in all the other centuries combined. Advances in medical knowledge have resulted not only from developments in technology but from increased access to current information provided through libraries such as the National Library of Medicine in Bethesda, Maryland.

Clinical Medicine↗
PubMed1995

The effect of nasal or oral gastric tubes on transesophageal atrial pacing thresholds.

This study was performed to evaluate whether the presence of either nasal or oral gastric tubes (GTs) would affect the ability to accomplish transesophageal atrial pacing (TAP). After endotracheal intubation, pacing esophageal stethoscopes were placed and the TAP thresholds were measured in 20 patients. With the PES fixed in position, GTs were inserted and pacing thresholds were remeasured. TAP was accomplished in all patients pre- and postinsertion. The mean +/- SD, range, and median TAP thresholds (mA) were 13.7 +/- 5.8, 7-25, and 12 preinsertion and 13.9 +/- 5.2, 5.5-25, and 13 postinsertion. The preinsertion-postinsertion differences ranged from -6 to 5 mA with a mean of the difference of -0.2 mA (95% confidence interval, -1.61-1.21 mA). No significant difference between the pre- and postinsertion groups was detected by the paired t-test, P = 0.77. In summary, the presence of GTs does not significantly affect TAP thresholds. Attempts to achieve TAP are expected to be successful in patients with either a nasal or oral GT in place.

Adult↗
PubMed1983

Evaluation of transesophageal Doppler detection of air embolism in dogs.

The authors assessed the use of a cylindrical sensor which transceives (transmits and receives) ultrasound in a 360 degree arc mounted on a standard esophageal stethoscope catheter to detect air embolism in dogs. They used electronic circuitry developed specifically to provide a continuous analog recording of high frequency Doppler energy as well as an audible signal. They found that the esophageal Doppler sensor was easy to position. In 25 of 30 dogs, the system distinguished Doppler sounds of venous air emboli that were present either in the superior vena cava, right atrium, right ventricle, or pulmonary artery from normal cardiovascular sounds. In the remaining five animals, Doppler heart and air emboli sounds were initially of poor quality, but improved with aspiration of air from the esophagus. In another five dogs, arterial air emboli produced by left ventricular injections also were detected. The esophageal sensor was sensitive to both venous and arterial air emboli ranging from 0.05--0.2 ml of air, and the authors consistently detected repeated intravenous injections of air throughout a 5-h time period. Optimal position of the sensor for detection of venous air emboli was at the level of the superior vena cava above its junction with the right atrium. Optimal position to detect arterial air emboli introduced via a left ventricular catheter was at the level of the aortic arch. Tissue analysis of the esophagus revealed no morphologic damage due to the sensor or transmitted energy.

Animals↗
PubMed1993

The effect of cricoid pressure on preventing gastric insufflation in infants and children.

BACKGROUND: The use of cricoid pressure for the possible prevention of regurgitation of gastric contents during induction of anesthesia in both adults and children has been recommended. However, equally important is the technique in possibly preventing insufflation of gas into the stomach. This study was designed to determine the efficacy of cricoid pressure application in preventing gastric gas insufflation in pediatric patients and to determine the airway pressure at which gas entered the stomach (pop-off point). METHODS: Fifty-nine patients, 2 weeks to 8 yr of age, physical status 1-4, scheduled for elective surgery, received an inhalational induction of anesthesia with halothane, N2O, and O2. A single observer used a stethoscope to auscultate over the upper abdomen for any air entry. In study I (without paralysis), the proximal airway pressure was slowly increased by gradually closing the pop-off valve on the anesthesia machine until gas was heard entering the stomach (pop-off point) or until the peak inspiratory pressure (PIP) reached 40 cm H2O. Thereafter, the pressurization procedure was repeated three times, altering the application and removal of cricoid pressure. The same patients were then paralyzed (study II), and the stomach evacuated before commencing an identical pressurization sequence with and without cricoid pressure. RESULTS: Appropriately applied cricoid pressure was 100% effective in preventing gas insufflation into the stomach of all children up to 40 cm H2O PIP with and without paralysis. In addition, paralysis significantly decreased the median pop-off point in any given patient. CONCLUSIONS: Appropriate application of cricoid pressure prevents gastric gas insufflation during airway management via mask up to 40 cm H2O PIP in infants and children. An additional benefit of cricoid pressure occurs in paralyzed patients in whom gastric insufflation occurs at lower inflation pressures.

Anesthesia, General↗
PubMed1994

Assessment of basic physical examination skills of internal medicine residents.

BACKGROUND: Internal medicine faculty at the Mayo Clinic designed a clinical evaluation exercise that separates assessment of physical examination skills from that of medical interviewing and reasoning skills. This report summarizes the first year's experience with assessment of basic physical examination skills. METHOD: A core faculty of five general internists and three internist subspecialists designed a 45-item general examination checklist (e.g., measure blood pressure, examine mouth, palpate liver, drape to ensure privacy). In addition, the core faculty generated a menu of 27 focused examination skills (e.g., examine for carpal tunnel syndrome) from which the faculty examiner would select five items for the resident to perform. Each checklist item was scored 0, 1, or 2 for a maximum possible score of 100. The core faculty selected a criterion-based scoring reference and established a passing score of 90 based on practice examinations with residents and faculty. The core faculty made an instructional videotape of a model examination that was available to all residents. In 1991-92, prior to examination, the checklist was distributed to all first-year categorical (43), preliminary (25), and newly appointed second-year residents (eight). RESULTS: Of the 76 residents examined, 11 (14%) failed and 65 (86%) passed. All failing scores were 86 or lower. The absence of scores 87, 88, and 89 suggested that faculty upgraded borderline performances. All 11 residents who initially failed retook the examination and passed. The five most commonly missed items were (1) inspect the skin, (2) complete examination in logical sequence, (3) palpate aorta, (4) auscultate anterior breath sounds, and (5) palpate axillary and inguinal nodes. Other important observed errors were failure to measure vital signs, confusion of liver and spleen, failure to use bell on stethoscope, and inadequate breast examination. Twenty-eight residents completed an optional feedback form. Reviews were mixed but generally favorable. CONCLUSION: Assessment of the basic physical examination skills of the internal medicine residents was useful, and such skills were able to be assessed separately from physical diagnosis skills and interviewing skills. Direct observation of basic physical examination skills revealed important deficiencies, which provided opportunity for remediation.

Adult↗
PubMed2002

Teaching and testing physical examination skills without the use of patients.

OBJECTIVE: To design a cardiopulmonary physical exam curriculum that does not involve the use of patients. Bedside teaching is becoming a lost art, and the use of alternative methods of instruction such as simulation has become increasingly important. Simulators have been shown to enhance physical examination skills of students and physicians in training.(1) DESCRIPTION: In 1995, a program was started to improve cardiopulmonary physical diagnosis and the teaching of auscultation at the University of Texas Medical Branch at Galveston (UTMB). The teaching manikin "Harvey" played a vital role in the development of the new curriculum. In 1997, UTMB adopted an organ-based approach to the basic science curriculum. The cardiopulmonary module in the basic science curriculum was a ten-week course taught in the second year of medical school. The physical diagnosis section of that course involved six instructional hours; four of the six hours were dedicated to cardiac auscultation and two hours to pulmonary auscultation. Only simulators and CD-ROMs were used for instruction. The 184 second-year medical students at UTMB were formed into small groups for instruction and practice. Although "Harvey" was an effective teaching tool, other simulators had to be developed for testing students' skills after instruction. It would be very difficult to administer a skills OSCE for 184 students without the development of several smaller transportable simulators. A commercially available blood pressure simulator from the Medical Plastics Laboratory, Inc., Gatesville, TX, was used to test the accuracy of students' blood pressure readings. Small auscultation transducers combined with a palpable pulse simulator, developed by one of the authors (WT) in collaboration with Andries Acoustics, Spicewood, TX, were used to efficiently test students' proficiency in cardiopulmonary auscultation. Digital simulated cardiopulmonary sounds were recorded onto a standard CD-ROM mini-disc and transmitted to the small transducers. Students used their own stethoscopes for auscultation. The targeted skills were efficiently tested in one hour of testing time per student. DISCUSSION: This cardiopulmonary instructional module was well received by the second-year medical students. In the skills OSCE, 80% of the students accurately measured systolic and diastolic blood pressure to within 5 mm Hg. Cardiopulmonary auscultation proficiency results showed average recognition of 60% for cardiac abnormalities and 88% for pulmonary sounds. Developing auscultation transducers with pulse simulation capability ensured that students could identify systole. Therefore, heart murmurs and sounds could be timed with the cardiac cycle. We found the results from the skills OSCE encouraging. Most students demonstrated reasonable competency in the skills taught, and the new transportable simulators performed well. The six-hour instructional module was meant to prepare students for their bedside teaching during the third year of medical school. The significant cost of the "Harvey" simulator may be a barrier to its widespread use for teaching. Therefore, continued development of smaller transportable simulators for teaching and testing purposes is important.

Clinical Competence↗
PubMed2002

Incorporating simulators in a standardized patient exam.

OBJECTIVE: Using simulated patients during a clinical skills exam that involves many students has the advantage of standardizing the delivery of historical data. One major disadvantage is the inability to standardize the physical exam findings. We designed a simulated patient exam that incorporates simulated abnormal physical exam findings. DESCRIPTION: The simulated patient exam case was divided into three separate stations: (1) the simulated patient's history, (2) the simulated physical exam, and (3) the presentation station. Dyspnea was chosen as the chief complaint because of the broad differential of possible cardiac and pulmonary auscultatory findings. In the first station, students obtained historical data from the standardized simulated patient. Students were graded on their ability to ask appropriate historical questions. Trained observers were used to verify the numbers of historical cues obtained by the students. The second station consisted of simulated physical exam findings. Students first measured the blood pressure on a commercially available blood pressure simulator arm from the Medical Plastics Laboratory, Inc., Gatesville, TX. Students then auscultated an abnormal digital heart sound and pulmonary sound from a small auscultation transducer developed by Andries Acoustics, Spicewood, TX. Students also palpated a simulated pulse from a newly developed pulse transducer. Digital cardiopulmonary sounds and pulse data were recorded onto a CD-ROM disc and transmitted to the small transducers via a CD-ROM disc player. Students used their own stethoscopes to auscultate cardiopulmonary sounds from the small transducers. The students were graded in the second station on their ability to accurately measure a blood pressure, identify abnormal cardiopulmonary digital sounds, and finally describe a peripheral pulse. In the third station, students presented the historical data and physical exam findings to a faculty member, and then provided a differential diagnosis list based on their key findings from the other two stations. A total of 171 students (n = 171) completed the simulated patient exam. Each student completed the exam in 45 minutes. DISCUSSION: In our simulated patient exam, students were evaluated not only on their data-gathering skills for key historical findings but also on the ability to correctly identify key physical exam findings such as abnormal cardiopulmonary sounds. Key physical exam findings were then integrated into the clinical decision-making process, which was presented in the faculty presentation station. Simulated patients with abnormal cardiopulmonary findings can be used for testing purposes. However, cardiac auscultatory abnormalities such as the ventricular S3 gallop are difficult to find and usually occur in a decompensated state such as heart failure. Other physical exam findings such as pulmonary crackles and wheezes also occur in decompensated conditions. Therefore, the use of simulators during a simulated patient exam offers the possibility of introducing several abnormal physical exam findings without having an unstable patient present in an exam setting. Further, the use of simulated physical exam findings allows for complete standardization of a clinical-simulated patient exam.

Clinical Competence↗
PubMedDate not supplied

Use of Doppler ultrasound in dissecting aortic aneurysm.

Immediate intensive therapy is of major importance in the initial management of patients with dissecting aortic aneurysm. The Doppler ultrasound stethoscope is a noninvasive tool which may be used in the diagnosis and management of this disease. A case is presented in which this instrument was used to diagnose and follow the progress of a patient with acute aortic dissection. Further use of this device for similar disorders can be expected.

Aortic Aneurysm↗
PubMed1984

Device for determining location of an endotracheal catheter tip.

The location of a catheter's tip in the bronchi may be determined using a stethoscope and an audible sound that has a frequency of 558 Hz and a sound pressure of 136 dB for the adult. The device is easy and safe to use, and has been used in a broad range of patients for over 4 yr without sequelae.

Auscultation↗
PubMed1991

Systolic and diastolic time intervals in the critically ill patient.

OBJECTIVE: The waveform of the first derivative of thoracic electrical bioimpedance was used to calculate systolic time intervals of the cardiac cycle, preejection period/left ventricular ejection time ratio, and diastolic time intervals, isovolumic relaxation period/filling time ratio. DESIGN: Prospective clinical study. Waveforms were examined from 913 normal and abnormal tracings from a thoracic electrical bioimpedance monitor. This monitor was coupled to a two-channel strip-chart recorder that identified preejection period/LV ejection time and isovolumic relaxation period/filling time in 86% of the tracings. SETTING: Two university-affiliated hospitals and one community hospital. PATIENTS: We assessed 100 subjects (ranging in age from 17 to 93 yrs) under various conditions. MEASUREMENTS AND MAIN RESULTS: Data from 15 normal subjects were used as a reference series to define normative values. Preejection period/left ventricular ejection time ratio was 0.35 +/- 0.1 (SD) and was consistent with data from systolic time intervals derived from simultaneous study of the ECG recording, carotid artery tracing, and phonocardiography. The diastolic time ratio (isovolumic relaxation period/filling time) was 0.4 +/- 0.2, in agreement with normal values derived by echocardiography and angiography. In a subgroup of 17 critically ill patients, a correlative study of simultaneously measured thoracic electrical bioimpedance, nuclear stethoscope, and radionuclide ventriculography was conducted. Systolic functions were compared by the ejection fraction derived by preejection period/left ventricular ejection time ratio displayed on the thoracic electrical bioimpedance monitor and by the radionuclide technique, and were found to be 57 +/- 13.8% and 58 +/- 8.6%, respectively (r2 = .49; y = 4.06x + 0.94; p less than .02; n = 17). Increased diastolic time ratios with normal or near-normal systolic time intervals were documented in nine (53%) of 17 critically ill patients with low systolic index. CONCLUSION: Both systolic and diastolic time intervals can be investigated noninvasively at the bedside by the thoracic electrical bioimpedance technique to provide a better understanding of left heart function.

Adolescent↗
PubMedDate not supplied

Problems with telemetry monitoring systems.

The purchaser of telemetry monitoring systems for operating and recovery rooms has little information available on the practical aspects of ownership and usage. To explore this problem, we recorded 76 telemetry failures (both operator and machine failure) occurring over six months among 18 telemetry channels located in operating and recovery rooms. We experienced approximately one telemetry failure every three days or every 60 surgical procedures. Factory repairs were required on 29 transmitters and 19 receivers during a two-year period. We observed that 28% of the failures were attributable to lead and electrode problems, 25% to battery depletion, 22% to mechanical or electronic component failures, 12% to inappropriate control settings and frequency mismatching, and 13% to miscellaneous difficulties. The following problems were observed. Transmitters were dropped frequently and occasionally immersed in liquids. Thus, waterproofing is recommended for OR use, and lead-failure warning circuitry is mandatory. Inappropriate control settings and frequency mismatching led to a previously unrecognized hazard: that is, it is possible to receive and display ECG data from the wrong patient located in a distant room. (Stethoscopic monitoring can be used to confirm that the data being displayed are from the correct patient.) Battery failure can occur at inopportune times, e.g., during cardiac arrest. Transmitters are frequently "lost" because of their small size and high mobility. This study indicated to us that, in the operating room, telemetry is not desirable because of its high cost compared to hard wired systems, poor reliability, and the possible hazard of displaying data from the wrong patient if improperly used.

Biomedical Engineering↗