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At least 19 recordsLinked to original sources

PubMed1999

Sonolysis of Albunex-supplemented, 40% hematocrit human erythrocytes by pulsed 1-MHz ultrasound: pulse number, pulse duration and exposure vessel rotation dependence.

The hypotheses tested were that sonolysis of erythrocytes in the presence of a gas-based ultrasound contrast agent in vitro will be related quantitatively to the duration and number of ultrasound pulses applied using a constant pulse repetition period and, at least qualitatively, to the total exposure duration (i.e., the product of pulse number x pulse duration). An objective was to determine the influence of sample rotation during insonation on the amount of hemolysis produced under these conditions. Human erythrocytes, suspended to 40% hematocrit in autologous plasma containing 3.6% (V:V) Albunex, were exposed/sham-exposed to 1-100 pulses of 1-MHz ultrasound (6.2 MPa peak positive, 3.6 MPa peak negative acoustic pressures; I(SPTP) approximately 800 W/cm2) using a 1-s pulse repetition period. Pulse durations ranged from 20-20,000 micros; samples were either stationary or rotated (200 rpm) during insonation. Hemolysis was independent of vessel rotation treatment at all tested pulse durations and pulse numbers. Levels of hemolysis statistically greater than in sham-exposed samples were obtained with > or = 50 pulses of 20 micros duration, and > or = 1 pulse of 200, 2000 or 20,000 micros duration. Hemolysis increased with increasing pulse number and pulse duration. Approximately equivalent levels of hemolysis were produced by different pulse number x pulse duration combinations, yielding the same total exposure duration.

Albumins↗

PubMed1987

Internal ventricular defibrillation with sequential pulse countershock in pigs: comparison with single pulses and effects of pulse separation.

We compared single to sequential pulse shocks with different pulse separations on internal cardiac defibrillation by using a catheter and plaque electrodes in open-chest halothane-anesthetized pigs. Ten seconds after fibrillation onset, defibrillation was attempted using trapezoidal pulses of 65% tilt, approximately 5 ms duration and fixed outputs from 1.0 to 50 joules (J). With single pulses, minimum defibrillation energy for the catheter alone was 2.4 +/- 0.3 J/kg (mean +/- standard error) and 2.1 +/- 0.2 J/kg for the catheter tip to plaque configuration. With sequential pulse shocks, the first pulse delivered via the catheter and the second pulse from the catheter tip to the plaque electrode, the energy necessary for defibrillation was dependent on the separation time between the two pulses (2.0 +/- 0.2, 1.5 +/- 0.2, 0.9 +/- 0.1, 1.3 +/- 0.3, 0.6 +/- 0.2, and 1.2 +/- 0.2 J/kg at 100, 10, 1, 0.5, 0.2, and 0.1 ms, respectively). Further, at the 0.2 ms separation, 100% of the animals could be defibrillated with less than 2.0 J/kg (35 J total). We conclude that sequential pulse defibrillation provides a significant improvement over single pulse defibrillation. The optimum separation between the sequential pulses in this study was 0.2 ms.

Animals↗

PubMed2002

Evaluation of pulse-duration on purpuric threshold using extended pulse pulsed dye laser (cynosure V-star).

BACKGROUND AND OBJECTIVES: Pulsed dye lasers (PDL) with extended pulse-durations create new opportunities in the treatment of vascular lesions. Development of extended pulse methods requires understanding of tissue effects of extended pulse-durations. We evaluated tissue effects of extended pulse-duration PDL (EPDL) with cooling. Effects of increasing pulse-duration, fluence, and multiple passes were evaluated to determine purpuric threshold and delayed purpuric response. STUDY DESIGN/PATIENTS AND METHODS: Ten patients were treated with EPDL and air-cooling on normal buttocks skin. Exposure pulse-durations of 0.5, 2, 20, and 40 milliseconds and increasing fluences 3-20 J/cm(2), pulse-duration dependent. Exposures were evaluated 0.5, 1, and 24 or 48 hours determining purpuric threshold and side effects. RESULTS: Immediate purpuric threshold increased from 6.2 to 8, 10.4, and 13.8 J/cm(2) at pulse-durations of 0.5, 2, 20, and 40 milliseconds, respectively. Purpuric threshold dropped after 24 hours to 5.2, 7.1, 9.3, and 11.9 J/cm(2), respectively. Multi-pass treatment lowered purpuric threshold by 1 J/cm(2). EPDL purpura resolved in less time than traditional PDL. No side effects were noted. CONCLUSIONS: EPDL exhibits increasing purpuric threshold with increasing pulse-durations, and risk of delayed onset of purpura.

Drug Administration Schedule↗

PubMed1997

Multicenter study on the clinical value of fetal pulse oximetry. II. Compared predictive values of pulse oximetry and fetal blood analysis. The French Study Group on Fetal Pulse Oximetry.

OBJECTIVE: Our purpose was to compare the predictive value of intrapartum fetal pulse oximetry with that of fetal blood analysis for an abnormal neonatal outcome in case of an abnormal fetal heart rate. STUDY DESIGN: A prospective multicenter observational study was conducted from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded with a Nellcor N-400 fetal pulse oximeter in case of an abnormal fetal heart rate during labor. Simultaneous readings of fetal oxygen saturation and fetal blood analysis obtained before birth (i.e., either at full dilatation or before cesarean section when indicated) were compared with the neonatal status. The criteria for an abnormal neonatal outcome were (1) an umbilical arterial blood pH < or = 7.15 and (2) a combined variable including 5-minute Apgar score < or = 7, umbilical arterial pH < or = 7.15, secondary respiratory distress, transfer in a neonatal care unit, or neonatal death. RESULTS: At a 7.20 threshold for fetal scalp pH and 30% for fetal oxygen saturation (i.e., the 10th percentile in the study population), the predictive value of fetal pulse oximetry was similar to that of fetal blood analysis for an arterial umbilical pH < or = 7.15 and for an abnormal neonatal outcome (positive predictive value 56% vs 55%, negative predictive value 81% vs 82%, sensitivity 29% vs 35%, and specificity 93% vs 91%, respectively). The receiver-operator characteristic curve showed similar performance of either technique for cutoff values < or = 7.20 for fetal blood pH and < or = 30% for fetal oxygen saturation, whereas fetal pulse oximetry became superior at higher thresholds. CONCLUSION: The predictive value of intrapartum fetal pulse oximetry can be favorably compared with that of fetal blood analysis. Randomized controlled management trials can now be performed to assess potential clinical benefits of this new tool.

Apgar Score↗

PubMedDate not supplied

[Comparison of central pulse pressure estimated from pulse wave propagation velocity and carotid pulse pressure measured by applantation tonometry].

BACKGROUND: Pulse pressure (PP) corresponds to the difference between arterial systolic blood pressure and diastolic blood pressure. Central PP seems to be a stronger coronary risk marker than brachial PP. Central PP can be estimated by aortic PP measured non invasively by aplanation tonometry of the carotid artery. The aim of this study was to compare 2 methods of estimation of aortic PP: estimation from Pulse Wave Velocities (PWV) and by aplanation tonometry of the carotid artery. Estimation from PWV is based on the non uniform transmission of the PP i.e. the amplification of PP from the aorta to brachial artery, through arteries of increasing impedance. METHODS: One hundred and fifty one subjects were included, 111 hemodialysis patients and 40 subjects free of cardiovascular treatment or cardiovascular organ damage, recruited in a preventive medicine setting. Central PP was measured by aplanation tonometry of the carotid artery. The following formula was used for the relationship between PP and PWV in the two arterial segments considered for pulse wave travel (waterhammer formula): [formula: see text] Where measurement of brachial PP (PPBr) and PWV at aortic (PWVAo) and brachial (PWVBr) gives an estimation of aortic PP (PPAo estimated). Carotid-femoral PWV was used for PWVAo and carotid-radial PWV was used for PWVBr. The two methods were compared by t-test and according to Bland and Altman's method. RESULTS: In the hemodialysis group (73 males, 44 +/- 12 years old), brachial PP was 56 +/- 15 mm Hg and central PP as measured at the carotid level was 47 +/- 15 mmHg. In the healthy group (29 males, 46 +/- 11 years old), these values were 46 +/- 10 mmHg and 35 +/- 10 mmHg respectively. Compared to carotid artery aplanation tonometry, PPAo estimated was larger than central PP by 2.9 +/- 6.3 mmHg in hemodialysis patients and by 5.4 +/- 6.6 mmHg in the healthy group. The difference was significantly larger in healthy subjects than in hemodialysis patients (p = 0.031). CONCLUSION: The PWV estimated PP is larger than the central PP measured at the carotid level by aplanation tonometry. The difference is larger in cardiovascular event free subjects than in patients on hemodialysis.

Adult↗

PubMed1993

[Pulse oximetry in the air rescue service. 2: Methods of increasing the stability of pulse oximetry measurements--ECG-synchronized pulse oximetry and adhesive sensors].

Pulse oximetric monitoring in air rescue service (rescue helicopter) is primarily influenced by motion artifacts (especially those of a passive nature), by low perfusion and by the problem of probe dislocation. In a prospective study involving 162 unselected emergency patients treated by the medical team of the emergency helicopter service "Christoph 22" (Ulm), we studied the possibility of reducing these adverse factors by applying available state-of-the-art technology, such as ECG-synchronization and adhesive probes. By applying the thus modified methods of monitoring, the interference factor was reduced to S = 0.056, that is only 5.6% of measurement time was adversely effected. The increase in measurement stability resulted from the reduction in number of described artifacts (motion artifacts and low perfusion), as well as from the reduction in duration of interfered measurement time. ECG-synchronization very effectively influenced the passive motion artifacts. Their frequency was reduced by the factor 8.2, respectively 42. An effective reduction in number of probe dislocations can be achieved by applying adhesive probes. The high costs of such probes presently limits their application. Radiation can be eliminated by redesigning the probe. ECG-synchronization of pulse oximetric signal has proved to be a method to reduce the artifacts frequently experienced in air rescue and has considerably contributed to the increase of emergency patient safety.

Aircraft↗

PubMed2001

Pulse oximetry for perioperative monitoring.

BACKGROUND: Monitoring with pulse oximetry might improve patient outcome by enabling an early diagnosis and consequently, correction of perioperative events that might cause postoperative complications or even death. Only a few randomised clinical trials of pulse oximetry have been performed during anaesthesia and in the recovery room which describe perioperative hypoxaemic events, postoperative cardiopulmonary complications and cognitive dysfunction. OBJECTIVES: To study the effect of perioperative monitoring with pulse oximetry to clearly identify the adverse outcomes that might be prevented or improved by the use of pulse oximetry. SEARCH STRATEGY: Trials were identified by computerised searches of the Cochrane Library, MEDLINE, EMBASE, and by checking the reference lists of trials and review articles. SELECTION CRITERIA: All controlled trials that randomised patients to either pulse oximetry or no pulse oximetry during the perioperative period, including the operating and recovery room. DATA COLLECTION AND ANALYSIS: We collected data in relation to events detectable by pulse oximetry, any serious complications that occurred during anaesthesia or in the postoperative period, intra- or postoperative mortality, and duration of recovery or intensive care stay. Formal statistical synthesis of individual trials was not performed in view of the variety of outcomes studied. MAIN RESULTS: Searching identified six reports; four studies with data from a total of 21,773 patients were considered eligible for analysis. Only two studies specifically addressed the outcomes in question; both found no effect on the rate of postoperative complications using perioperative pulse oximetry. Two studies used hypoxaemia detectable by pulse oximetry to assess the value of perioperative monitoring, although outcomes were not given. It was found that hypoxaemia was reduced in the pulse oximetry group both in the operating theatre and in the recovery room. During observation in the recovery room, the incidence of hypoxaemia in the pulse oximetry group was 1.5-3 times less. The postoperative cognitive function using the Wechsler memory scale and continuous reaction time was independent of perioperative monitoring with pulse oximetry. The other study showed that postoperative complications occurred in 10% of the patients in the oximetry group and in 9.4% in the control group. The two groups did not differ in cardiovascular, respiratory, neurologic, or infectious complications. The duration of hospital stay was a median of 5 days in both groups, and an equal number of in-hospital deaths was registered in the two groups. REVIEWER'S CONCLUSIONS: The studies confirmed that pulse oximetry can detect hypoxaemia and related events. However, we have found no evidence that pulse oximetry affects the outcome of anaesthesia. The conflicting subjective and objective results of the studies, despite an intense, methodical collection of data from a relatively large population, indicates that the value of perioperative monitoring with pulse oximetry is questionable in relation to improved reliable outcomes, effectiveness and efficiency.

Humans↗

PubMed1997

Pitch and loudness estimation for single and multiple pulse per period electric pulse rates by cochlear implant patients.

Numerical estimates of loudness and pitch for electric pulse rates were obtained from 14 patients using the 22 electrode cochlear implant manufactured by Cochlear Limited. Six patients were postlinguistically deafened adults, and eight patients were adults and children who became deaf very early in life. Comparisons were made between two types of pulse rate patterns. The SPP pulse pattern presented a single pulse every period, the inverse of the pulse rate. The MPP pulse pattern presented multiple pulses in the first half of the period, using a rate of 1000 pulses/s, with no stimulation in the second half of the period. The pulse rates used for the SPP and MPP pulse patterns were 71.4-500 pulses/s, which corresponded to periods of 14-2 ms. For the SPP pulse pattern, the total number of pulses over the duration of the stimulus increased with increases in pulse rate, while for the MPP pulse pattern, the total number of pulses remained constant. Pitch and loudness estimates were obtained from the postlinguistically deafened patients for the SPP and MPP pulse patterns, and from the early-deafened patients for the MPP pulse pattern. Loudness estimates for the SPP pulse pattern increased with increases in pulse rate for all postlinguistically deafened patients. Loudness estimates for the MPP pulse pattern decreased with increases in pulse rate for three of the six postlinguistically deafened patients and for six of the eight early-deafened patients. For the other patients (three postlinguistically deafened and two early-deafened), loudness estimates marginally increased with increases in pulse rate. Pitch estimates for the SPP and MPP pulse patterns increased with increases in pulse rate for the six postlinguistically deafened patients. For the early-deafened patients, pitch estimates for the MPP pulse patterns increased with increases in pulse rate for only five of the eight patients. For the other three early-deafened patients, pitch estimates were similar to the loudness estimates and decreased with increases in pulse rate.

Adolescent↗

PubMed1994

Responses of inferior collicular neurons of the FM bat, Eptesicus fuscus, to pulse trains with varied pulse amplitudes.

Under free field stimulation conditions, we studied the responses of inferior collicular neurons of the FM bat, Eptesicus fuscus, to pulse trains with varied pulse amplitudes. Each pulse train consisted of 7 pulses of 4 ms delivered at 24 ms interpulse-intervals (i.e. 42 pulses/s). For a control pulse train, all pulse amplitudes were equal to a neuron's best amplitude which, when delivered in single pulses, elicited maximal number of impulses from the neuron. The amplitudes of individual pulses of the remaining pulse trains were linearly increased or decreased at a slope of 0, 14, 28, 42, 56 and 69 dB/s. All 56 inferior collicular neurons discharged to pulse trains were of two main types. Type I (N43, 77%) neurons discharged to each pulse within a train while type II (N11, 20%) neurons discharged to the first pulse of a train stimulus only. Discharge patterns of the remaining (N2, 3%) neurons changed between type I and type II when stimulated with different pulse trains. The number of impulses discharged by a neuron varied with different pulse trains. In addition, the number of impulses discharged to each pulse by type I neurons also varied among individual pulses within the train. Only 14 neurons (25%) discharged maximally to the control pulse train. Responses of the remaining neurons to other pulse trains were either 30%-120% larger than (N17, 30%) or within 30% (N25, 45%) of the control pulse train response. Furthermore, half of 56 neurons selectively discharged to a most preferred pulse train with a response magnitude which was at least 50% larger than the response to the least preferred pulse train. Possible mechanisms underlying the different discharge patterns are discussed in terms of a neuron's recovery cycle, minimum threshold and inhibitory period relative to the temporal characteristics (pulse repetition rate and amplitude) of the pulse trains.

Acoustic Stimulation↗

PubMed1986

Dependence of double-pulse facilitation on amplitude and duration of the depolarization pulses at frog's motor nerve terminals.

Motor nerve terminals of the frog were depolarized by pairs of pulses with 5 to 10 ms interval and the resulting quantal transmitter releases were determined. In 'fixed pulse facilitation', Fc, the second pulse was kept constant, and the effect of a varying pre-pulse was measured, comparing the thus facilitated release after the fixed pulse to control release after the fixed pulse alone. If depolarization in the pre-pulse was increased from threshold to almost saturation level of release, Fc had a maximum, Fc, at about 1/10 the saturation level of release, as reported before. In 'double-pulse facilitation', Fd, two identical pulses were applied, and the facilitated release after the second pulse was compared to control release after the first pulse. On increasing pulse duration from 0.4 to 2.5 ms, at fixed depolarization levels, Fd had a peak at short pulse duration and low release, and declined with increasing pulse duration and release. This dependence is expected if facilitation is caused by 'residual Ca'. Alternatively, if at fixed duration depolarization in the pulses was increased from threshold level, in most preparations Fd rose to a maximum at low depolarization and release, declined to a minimum at the depolarization level of Fc, and rose again for larger depolarizations. In some preparations, and for short pulses, the peak of Fd at low depolarizations was not observed, but always Fd increased with depolarization beyond Fc. The complicated dependence of Fd on depolarization can be explained by the residual Ca theory, if at depolarizations larger than that which produced Fc and the minimum of Fd, Ca-inflow decreases.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

A prospective randomized comparison of defibrillation efficacy of truncated pulses and damped sine wave pulses in humans.

INTRODUCTION: Damped sine wave pulses have been used for nearly 50 years in transthoracic defibrillation systems. The purpose of this study was to determine whether damped sine wave pulses have a role in implantable defibrillators. METHODS AND RESULTS: In 21 survivors of cardiac arrest, we prospectively compared defibrillation efficacy of a standard truncated capacitor (RC) monophasic pulse with a damped sine wave inductor-capacitor (LRC) pulse using a right ventricular-left ventricular epicardial patch-patch electrode system. The RC pulse was a standard 65% tilt monophasic waveform generated from a 120 mu F capacitor. The LRC pulse was designed to simulate the waveform currently used in transthoracic defibrillators and was generated by passing the charge stored on a 40 mu F capacitor through a 37-mH inductor. Capacitor voltage, peak delivered voltage, peak delivered current, discharge pathway resistance, delivered energy, and stored energy were compared for the two waveforms at the defibrillation threshold. There was no difference in defibrillation efficacy for the two waveforms. Peak delivered voltage was similar at the defibrillation threshold: 313 +/- 101 V for the RC pulse and 342 +/- 119 V for the LRC pulse (P = 0.16). Similarly, no differences were found in defibrillation threshold peak delivered current: 8.6 +/- 2.5 (RC) versus 9.3 +/- 2.7 (LRC) amperes (A) (P = 0.20); discharge pathway resistance: 37 +/- 11 (RC) versus 38 +/- 13 (LRC) omega (P = 0.71); delivered energy: 7.0 +/- 4.5 (RC) versus 7.0 +/- 4.0 (LRC) joules (J) (P = 0.88); and stored energy: 8.7 +/- 5.7 (RC) versus 9.8 +/- 5.4 (LRC) J (P = 0.35). Although both waveforms performed the same, it was necessary to use substantially higher stored voltages with the damped sine wave delivery system than with the truncated waveform delivery system: 356 +/- 110 V for the RC pulse and 675 +/- 192 V for the LRC pulse (P < 0.0001). CONCLUSION: This study demonstrates that RC monophasic pulses provide equally effective epicardial defibrillation as LRC pulses with respect to delivered voltage and current and stored and delivered energy. However, in order for LRC pulses to provide comparable delivered voltage, current, and energy to that of RC pulses, nearly twice the voltage must be stored on the capacitor to accomplish the same task. These findings suggest that despite the nearly 50-year experience with damped sine wave pulses with transthoracic defibrillators, there is no need to begin using damped sine wave pulses for implantable defibrillators. Moreover, these data raise a question regarding the need for inductors in transthoracic defibrillators.

Aged↗

PubMedDate not supplied

Effect of simultaneous pulsed hyperthermia and pulsed radiation treatment on survival of SiHa cells.

Relatively mild temperatures (40-41.5 degrees C) can sensitize human cells to radiation without the development of thermal tolerance to radiosensitization. Therefore there may be a therapeutic benefit to adding mild hyperthermia to brachytherapy regimens for the treatment of cancer. However, the required heating times are long (approximately 48 h) which renders this approach somewhat impractical. A novel alternative is to combine pulsed brachytherapy with pulsed hyperthermia to enable the total radiation dose to be given at an elevated temperature while the total heating time is kept short. A treatment schedule in which 1 Gy radiation pulses were given once per hour during 5-min heating pulses also delivered once per hour, was investigated in vitro in the human cervical carcinoma line, SiHa. The degree of cytotoxicity and thermoradiosensitization of the cells were assessed by cell survival using the colony forming assay. Cells were exposed to pulsed hyperthermia alone (5 min at 45 degrees C, delivered once per hour), acute hyperthermia alone (45 degrees C), pulsed radiation alone (1 Gy per hour), acute radiation alone, and simultaneous pulsed hyperthermia and pulsed radiation. Pulsed heating alone caused little cytotoxicity. However when pulsed heating was added to pulsed radiation, the level of cytotoxicity was greater than for pulsed radiation alone or acute radiation alone. The effect was also greater than would be predicted from a simple additive effect of pulsed radiation and pulsed heating. In conclusion, pulsed heating at 45 degrees C sensitized cells to pulsed radiation without the development of thermal tolerance.

Cell Survival↗

PubMed1987

Intraoperative comparison of sequential-pulse and single-pulse defibrillation in candidates for automatic implantable defibrillators.

Sixteen survivors of cardiac arrest underwent intraoperative comparison of the effectiveness of sequential-pulse and single-pulse defibrillation. Defibrillation was tested alternately with the single-pulse or sequential-pulse technique 10 seconds into an episode of ventricular fibrillation that was induced with alternating current. The sequential-pulse defibrillation technique using truncated exponential pulses was performed with a right ventricular endocardial catheter and a left ventricular epicardial patch electrode. The first pulse was delivered between the right ventricular apical and the superior vena caval electrode on the right ventricular endocardial catheter. The second pulse was delivered between the right ventricular apical electrode and the left ventricular patch electrode 0.2 ms after termination of the first pulse. Single-pulse defibrillation was performed with a standard intracardiac defibrillation system in which a single truncated exponential pulse was delivered across 2 epicardial patch electrodes positioned over the anterolateral right ventricle and the posterolateral left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and integrated to determine delivered energy. Average defibrillation threshold leading-edge voltage for the sequential pulse technique was 496 +/- 140 V, compared with 365 +/- 157 V for the single-pulse technique (p less than 0.005). Defibrillation threshold leading-edge current for the sequential-pulse technique was 6.0 +/- 2.3 A, compared with 10.6 +/- 5.1 A for the single-pulse method (p less than 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1989

Prospective comparison of sequential pulse and single pulse defibrillation with use of two different clinically available systems.

Sixteen out-of-hospital survivors of ventricular fibrillation underwent a prospective, randomized, intraoperative comparison of sequential pulse and single pulse defibrillation with use of two distinct electrode systems and waveform shapes currently available for clinical use. Defibrillation was tested alternately with either the single pulse or the sequential pulse system 10 s into an episode of ventricular fibrillation. Sequential pulse defibrillation was performed with two 4 ms truncated exponential pulses of constant duration delivered to three equally spaced oval epicardial patch electrodes composed of concentric coils. The posterior left ventricular electrode served as the common cathode. The first anode was over the anterior right ventricle and the second anode was over the anterior left ventricle. Single pulse defibrillation was performed with the standard intracardiac defibrillation system with use of a single truncated exponential pulse with a fixed 65% tilt delivered across two rectangular, wire mesh epicardial patch electrodes positioned over the anterior right ventricle and posterolateral left ventricle. During defibrillation threshold determination, voltage and current waveforms were recorded and used to determine pulsing resistance and delivered and stored energy. Average defibrillation threshold leading edge voltage for the single pulse technique was 273 +/- 101 V compared with 246 +/- 67 V (11% less) for the sequential pulse technique (p = 0.136). Defibrillation threshold leading edge current for the single pulse technique was 6.7 +/- 2.5 A compared with 5.2 +/- 1.7 A (29% less) for the sequential pulse method (p = 0.005). The defibrillation threshold delivered energy was 5.6 +/- 4.0 J for the single pulse technique and 3.5 +/- 1.8 J (38% less) for the sequential pulse technique (p = 0.021).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2002

The reliable measurement of radial pulse: gender differences in pulse profiles.

This study was undertaken to determine whether healthy adults exhibited characteristic pulse profiles. Pulse characteristics measured for 83 women and 65 men included presence at the Traditional Chinese Medicine (TCM) locations (Cun, Guan, Chi); and depth (superficial, middle, deep), overall pulse force, relative pulse force, pulse width and pulse rhythm. Most subjects had similar values for many of the characteristics investigated including relative pulse force at the three traditional palpation locations (Cun, Guan and Chi), pulse width and pulse rhythm. There were some significant gender differences. The pulse was present beyond Chi in 90% of males compared with 56% of females. Female pulses tended to be less forceful compared with males. However, with the exception of overall force, there was little support for TCM assumptions of gender differences in pulse such as in left/right balance. There was some support for the use of the TCM palpation locations Cun, Guan and Chi to discriminate between pulses since there was significant differences in manifestations of some pulse characteristics among these locations.

Adult↗

PubMed1994

The retinal venous pulse. Its relation to optic disc characteristics and choroidal pulse.

PURPOSE: The presence or absence of the spontaneous retinal venous pulse is an important clinical sign, especially when one is evaluating a patient who may have increased intracranial pressure. The purpose of this study is to evaluate a large group of healthy patients, correlating optic disc characteristics, choroidal pulse, and brachial pulse pressure with the presence and intensity of the spontaneous retinal venous pulse. METHODS: Ninety-seven patients were studied correlating these parameters with their fundus photographs. Ocular pneumotonometry as a measure of the choroidal pulse and the brachial pulse pressure were correlated with the optic disc characteristics and the intensity of the retinal venous pulse statistically. RESULTS: The results showed a highly significant correlation with these parameters. The greater the pulse amplitude--especially the choroidal pulse the more likely the spontaneous retinal venous pulse would be present. More importantly, the anatomic variable of optic disc cup and vascular configuration had the greatest influence on whether the spontaneous retinal venous pulse is present or absent. CONCLUSION: The authors conclude that unless the clinician is aware of the importance of optic nerve characteristics and pulse amplitude in the choroid (indirectly measured in a normal clinical setting by the brachial pulse) the significance of the spontaneous retinal venous pulse cannot be properly determined.

Adolescent↗

PubMed1999

Depth of vaporization and the effect of pulse stacking with a high-energy, pulsed carbon dioxide laser.

BACKGROUND: Laser resurfacing of photodamaged skin has become popular, but questions regarding its safety with regard to the risks of scarring have arisen. OBJECTIVE: This study was designed to investigate the depth of vaporization and residual thermal necrosis of single-pulse vaporization and multiple passes versus pulse-stacking and multiple passes. The potential significance of operator technique and laser parameters is considered. METHODS: Skin samples from surgical excisions were treated by means of a Coherent Ultrapulse carbon dioxide laser at 250 mJ per pulse and 500 mJ per pulse with a 3 mm collimated beam and a repetition rate of 10 Hz. A total of 70 treatment areas were performed. Blinded analysis of the histologic effects of single-pulse, double-pulse, and triple-pulse vaporization after 1 through 10 passes was undertaken. RESULTS: A plateau of vaporization was observed after 3 passes at both 250 and 500 mJ whether single-, double-, or triple-pulse vaporization was used. This plateau occurs at approximately 100 to 250 microm from the skin surface. Thermal necrosis is well controlled only with single-pulse vaporization. There is a direct linear increase in the depth of thermal necrosis both with the number of pulses stacked and the number of passes. CONCLUSION: Pulsed carbon dioxide laser resurfacing is a safe and self-limited procedure if a pulse width of less than 1 msec is used with single-pulse vaporization and fluences of 3.5 J/cm2 and 7.0 J/cm2. There appears to be little justification for performing more than 3 or 4 passes. Pulse stacking may significantly increase residual thermal necrosis, thereby increasing the risk of scarring. Operator technique may be significant in avoidance of this occurrence.

Cicatrix↗

PubMed1996

Checking the carotid pulse check: diagnostic accuracy of first responders in patients with and without a pulse.

International guidelines for cardiopulmonary resuscitation (CPR) in adults advocate that cardiac arrest be recognized within 5-10 s, by the absence of a pulse in the carotid arteries. However, validation of first responders' assessment of the carotid pulse has begun only recently. We aimed (1) to develop a methodology to study diagnostic accuracy in detecting the presence or absence of the carotid pulse in unresponsive patients, and (2) to evaluate diagnostic accuracy and time required by first responders to assess the carotid pulse. In 16 patients undergoing coronary artery bypass grafting, four groups of first responders (EMT-1: 107 laypersons with basic life support (BLS) training; EMT-2: 16 emergency medical technicians (EMTs) in training; PM-1: 74 paramedics in training; PM-2: 9 certified paramedics) performed, single-blinded and randomly allocated, carotid pulse assessment either during spontaneous circulation, or during non-pulsatile cardiopulmonary bypass. Time to diagnosis of carotid pulse status, concurrent haemodynamics and diagnostic accuracy were recorded. In 10% (6/59), an absent carotid pulse was not recognized as pulselessness. In 45% (66/147), a pulse was not identified despite a carotid pulse with a systolic pressure > or = 80 mmHg. Thus, although sensitivity of all participants for central pulselessness approached 90%, specificity was only 55%. Both sensitivity and, to a lesser degree, specificity improved with increasing training; blood pressure or heart rate had no significant effect. The median diagnostic delay was 24 s (minimum 3 s). When no carotid pulse was found, delays were significantly longer (30 s: minimum 13 s), than when a carotid pulse was identified (15 s; minimum 3 s) (P < 0.0001). Of all participants, only 15% (31/206) produced correct diagnoses within 10 s. Only 1/59 (2%) identified pulselessness correctly within 10 s. Our cardiopulmonary bypass model of carotid pulse assessment proved to be feasible and realistic. We conclude that recognition of pulselessness by rescuers with basic CPR training is time-consuming and inaccurate. Both intensive retraining of professional rescuers and reconsideration of guidelines about carotid pulse assessment are warranted.

Adult↗