ECG) And Electroencephalogram Research Articles

Study on cortical arousal at voiding in term and preterm newborns monitored by electroencephalogram

Objective To investigate the voiding patterns of term and preterm newborns and whether voiding in term and preterm neonates was accompanied by any cortical arousal. Methods Between May 2013 and September 2013, 64 hospitalized newborns at Neonatal Intensive Cave Unit in the Frist Affiliated Hospital of Zhengzhou University were recruited in this study.In these patients, 31 cases were term newborns (20 male, 11 female) and 33 cases were preterm newborns(19 male, 14 female). The term and preterm newborns gestational ages at birth were(38.2±1.2) weeks and (32.1±1.6) weeks, weighted (3.3±0.4) kg and(1.7±0.3) kg, respectively and postnatal ages at study were[4-16(10.5±3.6)] days and [4-16(11.2±3.1)] days.The voiding volume (VV), post-void residual volumes(PRV), body movement rate and voiding frequency (VF) in 4 hours as well as the volume of milk and liquid fed at the same time frame were recorded and analyzed, retrospectively.At the same time electrocardiogram (ECG) and electroencephalogram (EEG) were recorded.The changes of heart rate (HR), EEG frequency, respiratory frequency (RF) during the 5 s period and 30 s before and after voiding onset were compared respectively.For cortical arousal definition the recommendations of the International Pediatric Work Group on Arousals (2005) were used. Results A total of 184 times of voiding were recorded.In preterm newborns, the VV and body movements rate were significantly lower compared with the term newborns[(21.8±7.9) mL and (41±21)% vs (26.4±8.7) mL and (62±19)%, t=3.75, 4.20, all P<0.05]. However, the VF and PRV were significantly higher in preterm newborns[(1.7±0.9) mL and (3.2±1.1) times vs (1.2±0.7) mL and (2.6±0.9) times, t=2.47, 2.38, all P<0.05]. Bladder voiding in these infants happened only during QS.In term newborns, HR frequency was higher during the 5 s interval before and after voiding onset when compared with the 30 s period before voiding onset[(152±6) times/min and (152±5) times/min vs (147±6) times/min, t=5.30, 5.76, all P<0.05] and the EEG frequency[(2.6±0.1) Hz and (2.6±0.1) Hz vs (1.5±0.1) Hz, t=70.0, 70.0, all P<0.05]. While the HR and EEG frequency of preterm neonate was not changed before and after bladder voiding onset.The RF of both term and preterm neonates were not changed before and after bladder voiding onset. Conclusions The voiding patterns between term and preterm were significantly different and cortical arousal was found only in term neonates, which indicate the term newborns have better mature bladder function and development of nervous system. Key words: Infant, newborn; Voiding; Cortical arousal

Evaluation of Bioelectric Signals for Human Recognition

Abstract This paper presents an evaluation of bioelectrical signals to use as a biometric for human recognition. Research shows that the impulses of cardiac rhythm, electrical activity of the brain recorded in Electrocardiogram (ECG) and Electroencephalogram (EEG) signals have unique features among individuals. The other bioelectrical signals such as Galvanic skin response (GSR), Electromyogram (EMG), Electrooculography (EOG) and Mechanomyogram (MMG) also process discriminaly information among individuals, so can be used as biometrics. The favorable characteristics to use these signals as biometrics include universality, measurability, uniqueness and robustness. In addition, they have the inherent feature of vitality that signify the life signs. Bioelectrical signals are highly confidential and secured to an individual. The issues involve using bioelectrical signals as biometrics are the variability of the signal, lack of standardization of signal features and the low energy. However, individuality of the bioelectrical signals is another issue that remains to be addressed.

Diagnostic Role of ECG Recording Simultaneously With EEG Testing

Arrhythmia is not uncommon in the etiology of syncope which mimics epilepsy. Data about the epilepsy induced vagal tonus abnormalities have being increasingly reported. So we aimed to evaluate what a neurologist may gain by a simultaneous electrocardiogram (ECG) and electroencephalogram (EEG) recording in the patients who underwent EEG testing due to prediagnosis of epilepsy. We retrospectively evaluated and detected ECG abnormalities in 68 (18%) of 376 patients who underwent EEG testing. A minimum of 20 of minutes artifact-free recording were required for each patient. Standard 1-channel ECG was simultaneously recorded in conjunction with the EEG. In all, 28% of females and 14% of males had ECG abnormalities. Females (mean age 49 years, range 18-88 years) were older compared with the male group (mean age 28 years, range 16-83 years). Atrial fibrillation was more frequent in female group whereas bradycardia and respiratory sinus arrhythmia was higher in male group. One case had been detected a critical asystole indicating sick sinus syndrome in the female group and treated with a pacemaker implantation in the following period. Simultaneous ECG recording in conjunction with EEG testing is a clinical prerequisite to detect and to clarify the coexisting ECG and EEG abnormalities and their clinical relevance. Potentially rare lethal causes of syncope that mimic seizure or those that could cause resistance to antiepileptic therapy could effectively be distinguished by detecting ECG abnormalities coinciding with the signs and abnormalities during EEG recording.

Electrophysiological Measures Applied in User Experience Studies

User experience refers to a person's perceptions and responses from their interaction with products. Electrophysiological techniques offer a possibility to measure user experience in real time. Three electrophysiological measures, Electrodermal activity(EDA), Electrocardiogram(ECG) and Electroencephalogram(EEG), were reviewed focusing on studies related to human cognitive and emotional state. Previous studies have found that the Skin conductance level(SCL) is related with emotional arousal level and cognitive engagement in EDA; Heart Rate(HR) is sensitive to emotional arousal and Heart Rate Variability(HRV) is sensitive to mental workload in ECG; and alpha and beta waves in EEG are valid indicators of emotional state and mental workload. However, these indices are not sensitive to the valence and categories of emotion. Future research could be developed in three aspects: identifying the valence and categories of emotion in user experience, integrating and synchronizing multiple indicators to identify emotional state in real time, and measuring aesthetic experience by physiological technology.

Sustained Attention Performance during Sleep Deprivation Associates with Instability in Behavior and Physiologic Measures at Baseline

To identify baseline behavioral and physiologic markers that associate with individual differences in sustained attention during sleep deprivation. In a retrospective study, ocular, electrocardiogram, and electroencephalogram (EEG) measures were compared in subjects who were characterized as resilient (n = 15) or vulnerable (n = 15) to the effects of total sleep deprivation on sustained attention. Chronobiology and Sleep Laboratory, Duke-NUS Graduate Medical School Singapore. Healthy volunteers aged 22-32 years from the general population. Subjects were kept awake for at least 26 hours under constant environmental conditions. Every 2 hours, sustained attention was assessed using a 10-minute psychomotor vigilance task (PVT). During baseline sleep and recovery sleep, EEG slow wave activity was similar in resilient versus vulnerable subjects, suggesting that individual differences in vulnerability to sleep loss were not related to differences in homeostatic sleep regulation. Rather, irrespective of time elapsed since wake, subjects who were vulnerable to sleep deprivation exhibited slower and more variable PVT response times, lower and more variable heart rate, and higher and more variable EEG spectral power in the theta frequency band (6.0-7.5 Hz). Performance decrements in sustained attention during sleep deprivation associate with instability in behavioral and physiologic measures at baseline. Small individual differences in sustained attention that are present at baseline are amplified during prolonged wakefulness, thus contributing to large between-subjects differences in performance and sleepiness.

A blind equalization algorithm for biological signals transmission

Direct transmission of biological signals such as electrocardiogram (ECG) and electroencephalogram (EEG) through mobile network provides practically unlimited movement of the patients and unlimited coverage area. However, transmission of such signals over a bandlimited channel or through a multipath propagation is subject to inter symbol interference (ISI), whereby adjacent symbols on the output of the channel smear and overlap each other causing degradation of error performance. Mitigation of such kind of distortion can be achieved through equalization filter. Recently an adaptive blind channel equalization using sinusoidally-distributed dithered signed-error constant modulus algorithm (DSE-CMA) has been proposed. In this paper we investigate the performance and the feasibility of this scheme for wireless ECG and EEG transmission. Also, this paper discusses the importance of adaptive blind equalizer for biological signals transmission over existing wireless networks such as Global System for Mobile Communications (GSM) and the Enhanced Data rates for GSM Evolution (EDGE). The geometrical-based hyperbolically distributed scatterers (GBHDS) channel model for macrocell environments was simulated with angular spreads (AS) taken from measurement data. Simulation results show that the low complexity of implementation and the fast convergence rate are the major advantages of deploying this scheme for telemedicine applications. It is also shown that the equalizer output signal is highly correlated with the original transmitted signal in time and joint time-frequency domains.

Cross-correlation of EEG frequency bands and heart rate variability for sleep apnoea classification

Sleep apnoea is a sleep breathing disorder which causes changes in cardiac and neuronal activity and discontinuities in sleep pattern when observed via electrocardiogram (ECG) and electroencephalogram (EEG). Using both statistical analysis and Gaussian discriminative modelling approaches, this paper presents a pilot study of assessing the cross-correlation between EEG frequency bands and heart rate variability (HRV) in normal and sleep apnoea clinical patients. For the study we used EEG (delta, theta, alpha, sigma and beta) and HRV (LF(nu), HF(nu) and LF/HF) features from the spectral analysis. The statistical analysis in different sleep stages highlighted that in sleep apnoea patients, the EEG delta, sigma and beta bands exhibited a strong correlation with HRV features. Then the correlation between EEG frequency bands and HRV features were examined for sleep apnoea classification using univariate and multivariate Gaussian models (UGs and MGs). The MG outperformed the UG in the classification. When EEG and HRV features were combined and modelled with MG, we achieved 64% correct classification accuracy, which is 2 or 8% improvement with respect to using only EEG or ECG features. When delta and acceleration coefficients of the EEG features were incorporated, then the overall accuracy improved to 71%.

Modular design of a long-term portable recorder for physiological signals

A portable biomedical signal recorder is valuable for the detection of acute symptoms. By the use of an ambulatory recorder, investigators and clinicians have more opportunity to analyze paroxysmal or sudden symptoms from the long-duration recorded signals. We propose a modular recorder that contains a motherboard, modules, and an isolated RS-232 interface. The modules have been modified to measure electrogastrogram (EGG), electrocardiogram (ECG), and electroencephalogram (EEG) signals. The compact motherboard includes a microcontroller with a built-in A/D converter, secure digital (SD) memory card, and the driven-right-leg (DRL) circuit. The power consumption of the proposed recorder is less than 2 mA (6 mW). It can continuously record a lead-II ECG signal with a 10-bit resolution for 3.9 days. As a result, the design is suitable for the purpose of long-term portable recording.

아웃도어웨어의 착용 쾌적성 평가를 위한 심전도 및 뇌파 분석

This study examines the comfort of outdoorwear by electrocardiogram (ECG) and electroencephalogram (EEG) analyses. An experiment that consisted of rest (30 min), exercise (30 min), and recovery (20 min) periods was administered in a climate chamber with 10 healthy male participants. Two kinds of outdoorwear made of 100% cotton fabrics (`Control`) and specially engineered fabrics having the feature of quick sweat absorbency and high speed drying fabric (`Functional`) are evaluated in the experiment. ECG and EEG signals were obtained during the rest and recovery periods for the two outdoorwear conditions. The ECG analysis identified a smaller decrement of high frequency (HF) power for the `Functional` when compared with the `Control` during the recovery period. Next, the EEG analysis showed that the relative band powers of slow and mid increased for the `Functional` while they decreased for the `Control` and that the ratio of power to high power was higher for the `Functional`. The evaluation results indicate that the participants could remain relaxed more with less stress while wearing the functional outdoorwear that demonstrated the positive effects on autonomic nervous system (ANS) activities. The present study is significant in regard that use of ECG and EEG for the assessment of wear comfort is the first in the field of clothing and textile.

Kainic acid seizure-evoked parasympathetic and sympathetic nerve activity and altered baroreceptor reflex responses in urethane-anesthesized rats

Kainic acid (KA) can cause limbic cortical seizure activity that generalizes to produce severe convulsions. Limbic seizures can spread to subcortical structures, producing severe autonomic consequences. We recorded from the vagus nerves in the neck region, renal sympathetic nerves, splanchnic nerves, and cervical sympathetic ganglia. In each animal, two or three nerves were recorded simultaneously. A femoral arterial catheter was used for blood pressure monitoring. Limb electrodes were used for electrocardiogram (ECG), and electroencephalogram (EEG) was recorded from the dorsal or ventral hippocampus. Vagus nerves were cut bilaterally (distally) to prevent fatal arrhythmias. KA (10 mg/kg, i.a.) was given to rats anesthesized with urethane or ketamine/xylazine. Baroreceptor reflex activity was assessed by recording nerve and ECG responses to nitroprusside (0.1 mg, i.a.) or phenylephrine (0.25 mg, i.a.). Modest sustained increases in vagus and sympathetic nerve activity were seen after KA when seizure activity was seen ventral hippocampus. A transient blood pressure decrease occurred in rats anesthesized with urethane but not ketamine/xylazine. After KA, neither sympathetic nor parasympathetic nerve activity changed in response to nitroprusside or phenylephrine challenges. EEG seizure discharges in dorsal hippocampus were associated with substantial additional sustained increases in firing, plus evidence of phasic seizure-related activity, in the vagus and sympathetic nerves. We conclude that KA alters sympathetic and parasympathetic neural activity by acting initially at ventral hippocampal regions. Limbic seizure discharges increase activity in both divisions of the autonomic nervous system, profoundly disrupting blood pressure regulation and heart rhythms.

Effectiveness of a training program for ECT nurses.

Electroconvulsive therapy (ECT) is a highly technical procedure requiring a team that consists of an anesthetist, a psychiatrist, a clinical nurse specialist, and recovery nurses. Traditionally, nursing education and training in the context of providing a safe and high standard of care has not been addressed. Ninety-two nurses from 42 different health agencies participated in a training program focusing on defibrillation, electrocardiogram (ECG) and electroencephalogram (EEG) monitoring, intubation, stimulus dosing, setting up the ECT equipment, and caring for the patient. A non-experimental, one-group, pretest-posttest research design was used in this study to evaluate the effectiveness of the training program for nurses working with ECT. Effective training for nurses was hypothesized to make a difference in the standards of practice and clinical effectiveness for patients undergoing ECT. Findings from this study indicated a major knowledge deficit in key components of ECT among nurses who have responsibilities in this area of nursing care. With effective training, nurses' confidence levels increased related to setting up the equipment, administering a double dose, helping with intubation, and using a defibrillator. If nurses are to effectively function as team members in the ECT procedure, they must receive the training necessary to prepare them for this important role. The results of this study support the recommendation of the Royal Australian and New Zealand College of Psychiatrists that ECT nurses should be appropriately trained in anaesthetic and resuscitation techniques and modern ECT practice.

High blood levels of nitric oxide in rats subjected to prolonged respiratory arrest and their modulation during adrenocorticotropin-induced resuscitation.

Anaesthetized rats, endotracheally intubated and mechanically ventilated with room air, were subjected to a 5-min period of asphyxia by turning off the ventilator. The ventilator was then turned back on and, simultaneously, the animals were treated with either the adrenocorticotropin fragment 1-24 [ACTH-(1-24), 160 microg/kg in a volume of 1 ml/kg i.v.] or an equivalent volume of saline. Nitric oxide (NO)-haemoglobin formation was detected ex vivo in arterial blood by electron spin resonance spectrometry; arterial blood pressure, electrocardiogram (ECG) and electroencephalogram (EEG) were monitored for a 60-min observation period, or until prior death. During asphyxia, there was massive formation of NO (red cell concentrations 40-80 microM), associated with a dramatic fall in mean arterial pressure and pulse pressure, marked bradycardia and ECG signs of ischaemic damage, as well as an isoelectric EEG. Treatment with ACTH-(1-24) produced a prompt (within 15 min) and long-lasting drop in NO blood levels, associated with an almost immediate (within 1 min) restoration of cardiovascular function and with a more gradual recovery of EEG, which became normal after 3040 min; all parameters remained stable throughout the 60-min observation period. In saline-treated rats, on the other hand, there was a further increase in NO blood levels, as detected 3 min after treatment, and all died within 5-8 min. Moreover, pretreatment and treatment with S-methylisothiourea sulphate (SMT, 3 mg/kg i.v.), a relatively specific inhibitor of inducible NO synthase, inhibited NO formation, but did not affect the mortality rate (100% within 5-8 min). The present results provide the first evidence that prolonged asphyxia is associated with high blood concentrations of NO, and that the life-saving effect of melanocortin peptides in severe hypoxic conditions is associated with a complete normalization of NO blood levels. However, the lack of SMT protection in this experimental model seems to rule out the possibility that the ACTH-(1-24)-induced resuscitation is due to an effect on NO overproduction.

Safety of high intravenous valproate loading doses in epilepsy patients

Parenteral antiepileptic drugs (AEDs) are required in patients needing emergent treatment or unable to take oral medication. In the two United States trials of IV valproate, only low therapeutic serum levels were achieved. This study evaluated the safety of high loading doses to achieve therapeutic levels rapidly. Twenty-five epilepsy patients without active seizures received a single loading dose of IV valproate (Depacon) based on body weight and infused over 1 hour. Ages were 4–39 years (mean: 13.1 ± 8.6 years). Electrocardiogram (ECG) and electroencephalogram (EEG) were monitored throughout infusion; blood pressure was measured before and after. Serum valproate was measured 10 minutes postinfusion. The IV valproate dose range was 15–44 mg/kg (mean: 28.3 ± 7.4 mg/kg); infusion rates were 0.25–0.73 mg/ kg/minute (mean: 0.47 ± 0.1 mg/kg/minute). Postinfusion serum valproate concentrations were 71–277 μg/ml (mean: 135.3 ± 59.5 μg/ml). There were no significant changes in blood pressure, no redness or tenderness at the IV site, and no ECG abnormalities. One patient with serum valproate ⩾ 200 μg/ml had mild sedation (resolving in 24 hours). We concluded that serum valproate concentrations of ⩾ 100 μg/ml can be achieved rapidly and safely parenterally, a finding with important implications for the treatment of status epilepticus.

Adrenocorticotropin counteracts the increase in free radical blood levels, detected by electron spin resonance spectrometry, in rats subjected to prolonged asphyxia

We investigated the influence of the adrenocorticotropic fragment 1–24 [ACTH-(1–24)] on the blood levels of highly-reactive free radicals in a rat model of prolonged asphyxia. Anesthetized animals were endotracheally intubated and mechanically ventilated with room air; after a 10 min stabilization period, the ventilator was turned off to induce asphyxia for 5 min; then, the ventilator was turned back on, and, simultaneously, the rats were intravenously treated with either ACTH-(1–24) (160 μg/kg in a volume of 1 ml/kg) or equivolume saline. Free radicals were detected in arterial blood by electron spin resonance spectrometry using an ex vivo method that avoids injection of the spin-trapping agent employed (α-phenyl-N-tert-butylnitrone). Arterial pressure, electrocardiogram (ECG) and electroencephalogram (EEG) were monitored for the 60 min observation period, or until prior death. At the end of the 5 min period of respiratory arrest, blood levels of free radicals were about four times higher than those of the basal, pre-asphyxia condition, arterial pressure had dramatically decreased, ECG showed marked bradycardia and signs of ischemic damage and the EEG had become isoelectric. Treatment with ACTH-(1–24) produced an immediate normalization of the blood levels of free radicals, associated with a restoration of cardiovascular function and full recovery of EEG within 30–45 min; all the saline-treated rats, on the other hand, died within 6.89 ± 0.96 min. These results provide direct evidence that in a severe condition of prolonged asphyxia there is a rapid and massive production of highly-reactive free radicals and suggest that the resuscitating effect of adrenocorticotropin fragments in severe hypoxic conditions may be largely due to the inhibition of free radical overproduction during tissue reoxygenation.

Sevoflurane is equivalent to isoflurane for attenuating bupivacaine-induced arrhythmias and seizures in rats.

The effects of sevoflurane on bupivacaine toxicity have not been defined. The purpose of this study was to investigate the effects of sevoflurane and isoflurane on bupivacaine-induced arrhythmias and seizures in rats. Thirty-seven Sprague-Dawley rats received bupivacaine intravenously at a constant rate of 2 mg.kg-1.min-1 until both arrhythmias and seizures occurred while electrocardiogram (ECG) and electroencephalogram (EEG) recordings were made. The cumulative doses of bupivacaine inducing arrhythmias and seizures were determined in the presence of 1 minimum alveolar anesthetic concentration (MAC) of sevoflurane (sevoflurane group, n = 14) or isoflurane (isoflurane group, n = 10) and in the absence of anesthetic (control group, n = 13). The cumulative doses of bupivacaine inducing arrhythmias and seizures were larger in the sevoflurane and isoflurane groups than in the control group and were similar in the sevoflurane and isoflurane groups. These results indicate that sevoflurane and isoflurane attenuate bupivacaine-induced arrhythmias and seizures in rats.

Sevoflurane Is Equivalent to Isoflurane for Attenuating Bupivacaine-Induced Arrhythmias and Seizures in Rats

The effects of sevoflurane on bupivacaine toxicity have not been defined.The purpose of this study was to investigate the effects of sevoflurane and isoflurane on bupivacaine-induced arrhythmias and seizures in rats. Thirty-seven Sprague-Dawley rats received bupivacaine intravenously at a constant rate of 2 mg centered dot kg (-1) centered dot min-1 until both arrhythmias and seizures occurred while electrocardiogram (ECG) and electroencephalogram (EEG) recordings were made. The cumulative doses of bupivacaine inducing arrhythmias and seizures were determined in the presence of 1 minimum alveolar anesthetic concentration (MAC) of sevoflurane (sevoflurane group, n = 14) or isoflurane (isoflurane group, n = 10) and in the absence of anesthetic (control group, n = 13). The cumulative doses of bupivacaine inducing arrhythmias and seizures were larger in the sevoflurane and isoflurane groups than in the control group and were similar in the sevoflurane and isoflurane groups. These results indicate that sevoflurane and isoflurane attenuate bupivacaine-induced arrhythmias and seizures in rats. (Anesth Analg 1996;83:570-3)

Changes in respiratory muscle activity in conscious cats during experimental dives at 101 ATA.

The rationale for the present study was to test the hypothesis that increased work of breathing during experimental deep diving may lead to respiratory muscle fatigue. For this purpose, electromyograms (EMGs) of respiratory and skeletal muscles, plus electrocardiogram and electroencephalogram (EEG) derivatives, were continuously recorded in conscious cats. In each muscle group, the ratio of power in a high (H) to that in a low (L) band of EMG frequencies was computed. Direct diaphragmatic stimulation in selected animals produced a mass action potential to obtain the muscle fiber conduction velocity (MFCV). The maximal pressure was 101 ATA (1,000 msw) with a maximal duration of 72 h. Four cats breathed an He-O2 mixture and five others a ternary mixture (10% N2 in He-O2). Inspired O2 partial pressure was 350 Torr. With the He-O2 mixture, all the animals died within 2-54 h during the study at maximal depth. EEG signs of high-pressure nervous syndrome (HPNS) were present in all cats, and low-frequency (11-14 Hz) hyperbaric tremor discontinuously contaminated all EMG tracings. The H/L ratio computed from diaphragmatic and intercostal muscle EMGs increased after 12 h at 101 ATA. With the He-N2-O2 mixture, the cats survived until the end of the sojourn at 101 ATA, during which no hyperbaric tremor was detected from EMG tracings, and EEG signs of HPNS were weak or absent. From 31 ATA, the H/L ratio decreased significantly in respiratory but not in skeletal muscles; this was associated with decreased MFCV in the diaphragm after several hours at maximal depth.(ABSTRACT TRUNCATED AT 250 WORDS)

Special Purpose Hybrid Computers for the Analysis of Electrocardiogram and Electro-Encephalogram

The importance of computers in medical research has been long recognized. With the availability of many medical instruments and recording devices, enormous amount of data is available in various forms. The analysis of physiological signals like electrocardiogram (ECG) and Electro-encephalogram (EEG) is very useful from the clinical point of view. These signals possess a large amount of hidden information about the physiological conditions of the related organs. ECG and EEG produce different types of patterns that the eye of the physician has empirically correlated with the important aspects of health. The computers use these relations and perform the analysis automatically with greater precision and accuracy.The acquisition, reduction and analysis of data which lead to final interpretation should be treated as a single information processing task. Also since there is immense amount of physiological data which is to be analysed on-line within a short time, special purpose computers serve very useful purpos...

New Horizons in Biomedical Engineering

A gap has existed between the physical and the medical sciences. The theoretical treatment of problems by the engineer has been considered by the physician as being far removed from the patient, while the engineer has considered the doctor's approach to treating patients as empirical and nonscientific. A new science, biomedical engineering, is now arising which bridges the gap between the physical sciences and the life sciences and which draws upon each for support. This merging of the physical and life sciences began about the time of World War II with the occasional collaboration on a new instrument between someone with a background in physics or in an engineering science and an associate from medicine or from one of the basic biological sciences. From such exchanges of information evolved the present multidisciplinary approach to problems in medical treatment, research, and training. Today, physicists, mathematicians, and engineers routinely join with the biologist and physician in developing techniques, equipment, and materials. In its initial phases the area was represented by a small group of men with a common interest in developing physical methods of measurement in the field of medicine. Most of these individuals were M.D.'s or Ph.D.'s in the clinical or preclinical sciences who had training and an interest in mathematics, physics, electronics, or computer technology. Others were engineers who had developed a competence and an interest in the life sciences. From such collaboration came bloodflow transducers, new electrocardiogram (ECG) and electroencephalogram (EEG) techniques, and new methods of measuring respiration and blood pressure.