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At least 991 records · Page 55Linked to original sources
PubMed2001

Event-related potentials, CNV, readiness potential, and movement accompanying potential recorded from posterior thalamus in human subjects. A SEEG study.

Intracranial recordings were obtained from three patients with intractable chronic pain who underwent analgesic electrical stimulation of the contralateral thalamus. Multilead electrode made it possible to record from several thalamic nuclei. The electrode was targeted into the ventroposterolateral (VPL) nucleus of the thalamus. During separate recording sessions, the following tests were performed: somatosensory evoked potentials (SEP) of the median or posterior tibial nerve, event-related cognitive potentials (auditory oddball P3 wave), readiness potential (RP) and contingent negative variation (CNV) using auditory warning (S1) and visual imperative (S2) stimuli. The movement accompanying potential (MAP), which was present in the VPL in all but one of the recordings, behaved as a far-field potential. Recordings obtained from the VPL confirmed its established role as a relay nucleus, processing somatosensory information to the primary somatosensory cortex. The VPL generated the 'thalamic' SEP, which was the only potential regularly recorded in this nucleus. In the recordings from one patient (No. 3), auditory and visual evoked potentials of the CNV protocol, peaking at approximately 300 ms, were obtained from the VPL and appeared to be generated in situ. Neither RP, CNV nor 'oddball' ERPs appeared in the VPL. From the pulvinar, only a visually evoked potential was recorded. Oddball P3, RP, CNV, and middle and long latency auditory and visual potentials (evoked in the CNV paradigm) appeared to be generated 'dorsally' to the VPL, probably in the nucleus posterolateralis (PL). This structure may therefore be involved in both the processing of afferent information and in cognitive operations.

Aged↗
PubMed2003

Techniques for recording renal sympathetic nerve activity in awake, freely moving animals.

The methods described here allow recording of sympathetic nerve discharge in awake, freely moving animals, and follow a historical perspective of the different techniques developed over the years to record sympathetic discharge. The length of time each system is viable for recording varies from days to weeks. Also included are special hints for the surgical implantation of recording electrodes, types of recording electrodes and cables, as well as the minimum equipment necessary for recording sympathetic discharge. Lastly, a section on troubleshooting includes how to remove movement artifacts and extraneous noise, and minimize the destruction of leads common in recording in awake, freely moving animals. This article is written for the beginner or novice with an emphasis on what is needed when embarking on recording sympathetic nerve discharge in awake, freely moving animals.

Animals↗
PubMed2003

The selective gating of the N30 cortical component of the somatosensory evoked potentials of median nerve is different in the mesial and dorsolateral frontal cortex: evidence from intracerebral recordings.

OBJECTIVE: The somatosensory evoked potentials of the median nerve (SEP) were registered intracerebrally in 12 subjects to elucidate the origin of N30 component and its behavior in the motor 'gating' tasks. METHODS: The recordings were done from the electrodes which were inserted within the cortex of frontal lobe in the pre-surgical phase of epilepsy surgery. The registrations focused on the precentral N30 SEP component and its behaviour under the 'gating' paradigms. Two different 'gating' paradigms, motor and mental, were used and the SEP then were recorded in 3 conditions: (1) normal (N) paradigm, during which the subjects were instructed not to perform any movement by the stimulated hand, or to mentally simulate the movement; (2) active movement (AM) paradigm, during which the subjects were instructed to perform the active movement as the internal motor sequence test by the fingers of the hand of the stimulated limb; (3) mental movement simulation (MMS), during which the subjects were instructed to only mentally simulate the movements performed in the previous paradigm, and this 'virtual' movement also involved the hand of the stimulated limb. The recordings were done at least twice in each paradigm and averaged runs of 2000 artefact-free sweeps were used for the analysis. RESULTS: The results demonstrated that the precentral N30 component of SEP is generated only in the pre-motor area, either dorsolaterally or mesially, which consists of Brodmann's areas 6 and 8, and their borders. Only the N30 potentials recorded there in 7 subjects had a shape and character of 'near-field' potential. The behaviour of the N30 component when recorded in the AM and MMS paradigms was different depending on the fact of whether they were recorded dorsolaterally or mesially. When there was a clear 'near-field' N30 potential recorded mesially, there was a certain gating present during the AM paradigm, i.e. during the performance of movement. However, the gating caused by the mental movement simulation in the MMS paradigm was substantially more expressed, and the N30 wave practically disappeared in some cases. On the contrary, the gating of the N30 wave, recorded in the frontal dorsolateral premotor cortex (DLPC), was almost complete when the AM (active movement) paradigm was employed, and it was only partial when the MMS paradigm (mental movement simulation) was employed. CONCLUSIONS: The results of N30 registrations in our group of patients strongly support the theory of separate generator (or generators) of the N30 wave within the premotor cortex. They also brought forward evidence that the dorsolateral premotor cortex (Brodmann's areas 6 and 8) serves as the substrate of the 'motor execution' process, and the mesial frontal cortex (Brodmann's area 6) serves as the substrate of the 'motor planning' process. Further research should focus on the mutual registration of neurophysiological phenomena and imaging phenomena to obtain new data, which will be able to more precisely elucidate the workings of the premotor cortex during the whole process of motor performance.

Adult↗
PubMed1997

Determination of appropriate recording force for non-invasive measurement of arterial pressure pulses.

1. Non-invasive recording techniques of the arterial pressure pulse will distort the arterial wall and may alter pulse wave measurements. We hypothesized that intersubject variability of these measurements would be reduced if recording forces were normalized to reflect individualized arterial occlusion forces. 2. In 10 normal male subjects (age 24 +/- 1 years), brachial, radial and finger arterial pressure pulses were recorded simultaneously using volume displacement pulse transducers (Fukuda TY-303) and a finger pressure monitoring system (Finapres, Ohmeda 2300) and were made at 2, 5 and 10-100% (10% increments) of the brachial arterial force associated with marked distortion of finger pulsations. Forces were applied at the brachial site in a randomized order while a constant 1.8 N force was applied at the radial artery site. Pressure pulses were analysed using the discrete fast Fourier transform. 3. Pulse amplitude, contour, wave velocity and relative transmission ratios remained relatively constant until the branchial artery recording force exceeded 59.9 +/- 0.3% of the largest recording force used in each subject (7.14 +/- 0.75 N). The finger pulse pressures (P < 0.0001), radial pulse amplitudes (P < 0.0001) and contours (harmonics 2-6, P < 0.003), pulse wave velocity (P < 0.021) and relative transmission ratios (harmonics 3-7, P < 0.01) then decreased with higher recording forces. 4. To avoid distortion, non-invasive recordings of arterial pressure pulse amplitude, contour, pressure wave velocity and relative transmission ratios along a peripheral arterial segment should use recording forces of less than 60% of the force associated with marked distortion of finger pulsations.

Adult↗
PubMed1998

Analogue and digital electrocardiogram recordings in the assessment of heart rate variability.

We compared analogue and digital 24-h electrocardiogram (ECG) recordings in the assessment of heart rate variability (HRV) in 41 patients with suspected coronary artery disease. The patients underwent ambulatory ECG recordings simultaneously with analogue (A) (Marquette 8500) and digital (D) (Oxford Medilog FD-3) recorders. Digital ECG recordings were analysed with the Excel Medilog II system (DE) and analogue recordings were analysed with both Marquette (AM) and Excel Medilog II (AE) systems. SDNN, SDANN, rMSSD and pNN50 were calculated for the assessment of time domain measures of HRV, and powers of low (0.04-0.15 Hz) and high (0.15-0.40 Hz) spectral components of HRV for the assessment of frequency domain measures of HRV. Correlations between time domain measures of HRV derived from AM, AE and DE recording and analysis techniques were high (r = 0.803-0.999, P < 0.001). SDANN and pNN50 assessed with AM and DE were equal, whereas SDNN and rMSSD values differed slightly but significantly from each other (P < 0.01 for both). All time domain measures of HRV assessed with AE differed significantly from AM (P < 0.001) and from DE (P < 0.01). Correlations between frequency domain measures of HRV derived from AM, AE and DE were also high (r = 0.973-0.992, P < 0.001). Despite this, frequency domain measures of HRV assessed with AM, AE and DE differed significantly from each other (P < 0.001). In conclusion, when analysed with their own analysis systems, analogue and digital recordings provided almost identical time domain, but not frequency domain, measures of HRV. In addition, analysis of an ECG recording with an analysis system of different manufacturer should be avoided.

Aged↗
PubMed2000

Recording monophasic action potentials using a platinum-electrode ablation catheter.

AIMS: The monophasic action potential (MAP) is conventionally recorded using Ag-AgCl electrodes which are not suitable for delivering radiofrequency currents. To be able to use the sharp MAP upstroke for identifying the local activation, as a step towards the development of a MAP-guided catheter ablation technique, the possibility of recording MAP via platinum electrodes of an ordinary ablation catheter was explored. METHODS AND RESULTS: One hundred and forty-two MAP recordings from the endocardium were obtained via an ablation catheter in 40 patients undergoing electrophysiological study/catheter ablation. During sinus rhythm and pacing, 90% of the ventricular and 100% of the atrial MAPs had stable baselines. The amplitudes were 13 +/- 4.2 mV for ventricular and 2.4 +/- 0.8 mV for atrial MAPs. During mapping and ablation, MAPs and uni- and bipolar electrograms were recorded simultaneously using the same tip electrode in eight patients. The MAPs provided more distinct local activation than the electrograms. During 17 MAP recordings, additional MAPs were recorded simultaneously using an Ag-AgCl electrode catheter in the immediate vicinity of the ablation catheter. The MAPs taken with the ablation catheter had characteristics consistent with those taken with the Ag-AgCl catheter. CONCLUSIONS: (1) Platinum electrodes can be used for timely recording of MAPs in patients. (2) It is feasible to record MAPs and deliver radiofrequency currents via the same platinum-tip electrode. These findings suggest that MAP-guided catheter ablation is technically possible.

Action Potentials↗
PubMed2001

Linear versus non-linear recordings of transiently-evoked otoacoustic emissions--methodological considerations.

A non-linear technique is predominantly used for the recording of transiently-evoked otoacoustic emissions (TEOAEs). The aim of this study was to compare linear and non-linear TEOAE recordings. TEOAEs were recorded in 22 normal hearing subjects to clicks from 90 to 30 dB SPL in 10 dB steps with the ILO88 system using both linear and non-linear recording techniques. The non-linear recording technique reduces stimulus artifacts for early latencies, but total elimination could not be proved. Both artifact reduction and significant differences between the two kinds of TEOAE recordings were reduced for longer latencies and lower stimulus intensities. For longer latencies (>10 ms) there was no significant difference between "linear" and "non-linear" TEOAEs. A higher signal-to-noise ratio was found for "linear" TEOAEs, resulting in better identification and a higher test-retest correlation. The linear recording technique, which includes new methods of artifact cancellation in comparison to the mainly utilized non-linear recording technique, should be used especially in hearing screening.

Female↗
PubMed1981

Validation of a dietary record system for the estimation of daily cholesterol intake in individual outpatients.

In order to develop a reliable system for measuring daily cholesterol intake in individual outpatients, studies were undertaken to establish the shortest time period (in days) for which it is necessary to obtain daily food intake records. Three volunteers were trained in dietary record-keeping and portion-size assessment, and instructed to self-select a low-cholesterol diet for 20 days. During the study period they maintained daily dietary records and collected dummy diets. Comparisons of cholesterol intake calculated from the dietary records (mean 144 mg/day, SD +/- 13, n = 60) to the values from chemical analysis (118 +/- 28 mg/day) demonstrated that the calculated values were higher (mean 19%). More importantly, it was found that a minimum of 9 days' records of dummy diet analyses were required in order to reach an estimate of daily cholesterol intake that varied by less than 10% from the mean of the 20-days' values. In 100 outpatients trained to adhere to a moderately low-cholesterol intake and who maintained sequential dietary records for 9 days, it was found that the mean daily intake was 251 mg/day but that individual patients exhibited substantial daily variations in cholesterol intake (average coefficient of variation = 54%, range = 8.5 to 121.2%). These results demonstrate that, under conditions of training in dietary record-keeping and portion-size assessment, adherence to a low-cholesterol diet, and with collection of at least 9 days of dietary records, a reliable quantitative estimate of daily dietary cholesterol intake can be obtained in free-living outpatient populations.

Ambulatory Care↗
PubMed1999

Focal ictal direct current shifts in human epilepsy as studied by subdural and scalp recording.

In order to clarify further the characteristics of ictal direct current (DC) shifts in human epilepsy, we investigated them by subdural and scalp recording in six and three patients, respectively, both having mainly neocortical lobe epilepsy (five with frontal lobe epilepsy, two with parietal lobe epilepsy and two with temporal lobe epilepsy). By using subdural electrodes made of platinum, ictal DC shifts were observed in 85% of all the recorded seizures (89 seizures) among the six patients, and they were localized to just one or two electrodes at which the conventional initial ictal EEG change was also observed. They were closely accompanied by the electrodecremental pattern in all patients except for one in whom 1 Hz rhythmic activity was superimposed on clear negative slow shifts. Seizure control after resection of the cortex, including the area showing DC shifts, was favourable irrespective of histological diagnosis. Scalp-recorded ictal slow shifts were observed in 23% of all the recorded seizures (60 seizures) among the three patients. They were, like the subdurally recorded ones, mainly surface-negative in polarity, closely related to the electrodecremental pattern and consistent in their location. It seems that scalp-recorded DC shifts were detected particularly when seizures were clinically intense, while no slow shifts were observed in small seizures. It is concluded that at least subdurally recorded ictal slow shifts are clinically useful before epilepsy surgery to delineate more specifically an epileptogenic area as well as to further confirm the conventional initial ictal EEG change, and that scalp-recorded ictal slow shifts also have high specificity although their low sensitivity is to be taken into account.

Adolescent↗
PubMed1988

Relation of monophasic action potential recorded with contact electrode to underlying transmembrane action potential properties in isolated cardiac tissues: a systematic microelectrode validation study.

Monophasic action potentials, recorded with contact non-suction electrodes, have been used both clinically and experimentally. However, to date no systematic microelectrode validation studies have been done to underlying myocardial cell populations from different myocardial regions with different transmembrane potential profiles. In the present study transmembrane action potential properties, recorded with standard microelectrodes, were compared with monophasic action potentials recorded with contact electrodes in three different (endocardium, epicardium, and free running Purkinje fibre) isolated canine preparations during pacing and during spontaneous automatic activity. The mean transmembrane durations at 50% and 90% repolarisations (APD50 and APD90) of 19-30 cells at a monophasic action potential recording site was not statistically significant from monophasic action potential duration in all three tissue preparations studied. However, in endocardial preparations, composed of superficial (1-2 cell layers) Purkinje fibres with deeper ventricular muscle cells, the APD50 (139(17) ms) and APD90 (181(26) ms) of monophasic action potentials more closely reflected (but not significantly different) the underlying deeper ventricular muscle cells (APD50 134(14) ms and APD90 167(15) ms) rather than the mean transmembrane action potential durations of the underlying most superficial Purkinje fibres (166(22) ms for APD50 and 210(30) ms for APD90) (p less than 0.025). Tetrodotoxin (TTX) at 1 x 10(-6) mol.litre-1 shortened Purkinje fibre action potential duration and slightly lengthened that of ventricular muscle. Simultaneously recorded monophasic action potential showed an intermediate change in action potential duration. Incremental pacing and applied single premature stimuli resulted in similar degrees of shortening of action potential duration for both monophasic action potential and transmembrane potential in all three preparations. In endocardial preparations, barium chloride (4 mmol.litre-1) superfusion induced early afterdepolarisations, and spontaneous phase 4 depolarisations (n = 6) in both Purkinje and ventricular muscle cells giving rise to spontaneous automatic activity. These abnormal automatic activities were accurately detected by simultaneous monophasic action potential recordings. Suppression of automaticity by verapamil (0.2-0.5 micrograms.ml-1) as confirmed by transmembrane action potential recordings were similarly detected by monophasic action potential recordings (ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed2006

One-year follow-up in a prospective, randomized study comparing radiofrequency and cryoablation of arrhythmias in Koch's triangle: clinical symptoms and event recording.

AIMS: To rely solely on clinical symptoms of recurrent palpitations to evaluate the success of interventional procedures can be misleading. This study was designed to assess the efficacy of event recording in evaluating long-term success in patients treated for atrioventricular nodal reentrant tachycardia (AVNRT) or right posteroseptally located accessory pathways (RPS) either by radiofrequency (RF) or by cryoablation (CA). METHODS AND RESULTS: Sixty-three patients with AVNRT and eight with RPS were randomized. Patients were encouraged to activate an event recorder in the case of recurrent palpitations for the first 3 months. One year after the procedure, patients were asked specific arrhythmia related questions. Thirty-six patients underwent RF and 35 CA. Acute success was finally achieved in 34 (94%) patients in the RF and 33 (94%) in the CA groups. Assessment of long-term success demonstrated a similar proportion of palpitations in the RF and CA groups: 11 (31%) vs. 17 (49%). Only 12 patients activated the event recorder, four patients in RF, including one patient with chest pain, and eight in the CA group. Analysis of recordings revealed recurrent AVNRT or circus movement tachycardia in four patients (one RF and three CA), atrial fibrillation in one RF patient, and sinus tachycardia in six (one RF and five with CA). In addition, a complete 12 lead ECG of a recurrent arrhythmia was made in three RF and two CA patients (in-hospital or after the event recording). A total of seven patients underwent a second procedure (four RF and three CA). Without the event recorder, seven patients would have been misclassified as having recurrent arrhythmia. CONCLUSION: Event recording enhances the sensitivity of detecting arrhythmia recurrences in evaluating therapy efficacy and should be considered in every interventional follow-up study. Analysis of recordings showed that CA is as effective as RF in the treatment of AVNRT and RPS at long-term follow-up.

Arrhythmias, Cardiac↗
PubMed1987

Misclassification of nutrient intake of individuals and groups using one-, two-, three-, and seven-day food records.

In this study, 6,844 food records were collected during three years (1979-1982) from 106 volunteer Wisconsin women, aged 35-65 years. Subjects recorded all intake of food, and vitamin/mineral supplements on a structured, precoded form. One-, two-, three-, and seven-day records were compared with usual intake of calcium, kilocalories, vitamin A, and vitamin C. Usual intake was calculated using 37-72 food records per subject. Estimates of group means from a small number of records were not significantly different from mean usual intake (p greater than 0.05). Correlations with usual intake ranged from 0.43-0.64 and from 0.71-0.90 for the one day and the seven-day estimates, respectively. For the one-day record, 43-67% of subjects were correctly classified to the extreme quintiles of intake, 52-76% for the seven-day record. Classification was least good for vitamin A, better for other nutrients with lower intraindividual variance. However, overall agreement with usual classification of assignment to quintiles even with the seven-day record was less than 55% for all four nutrients. Effects at extremes of intake might be more easily analyzed than dose-response relations.

Adult↗
PubMed1999

Effect of positioning on recorded lung sound intensities in subjects without pulmonary dysfunction.

BACKGROUND AND PURPOSE: Physical therapists often use positioning to assist in the reexpansion of collapsed lung segments. An increase in lung sound intensity on auscultation is considered indicative of lung expansion. This study was designed to examine whether clinical interpretation of auscultatory findings is warranted. SUBJECTS: The subjects (5 male, 6 female) were young physical therapist students without pulmonary dysfunction (mean age=20.4 years, mean height=166.3 cm, mean weight=57.5 kg). Subjects with lung disease were excluded because pulmonary pathology is difficult to standardize. METHODS: Lung sounds electronically recorded over the posterior chest wall of subjects in sitting and side-lying positions were compared. Measures included peak intensity, frequency at maximum power, and median frequency. RESULTS: In the sitting position, inspiratory sounds recorded over the left posterior chest wall were louder than those recorded on the right side. In the side-lying positions, the sound intensity recorded from the dependent chest wall was louder than that recorded from the nondependent chest wall. In side-lying positions, the upper hemithorax is "nondependent," and the side in contact with the bed is "dependent." Sound intensities recorded over both posterior chest walls in the sitting position were louder than those recorded over the same lung area in the nondependent side-lying position. There was no difference in the sound intensity recorded between the sitting and dependent side-lying postures. CONCLUSION AND DISCUSSION: When comparative auscultation of the chest wall is used by physical therapists to assess the adequacy of pulmonary ventilation, patient posture and regional differences in breath sound intensity can influence clinical interpretation.

Adult↗
PubMed1981

Comparisons of home sleep recordings and polysomnograms in older adults with sleep disorders.

A major problem with studying the prevalence of sleep disorders is the high cost. We tested a portable home recording system which can decrease the cost of screening sleep recordings. Twenty-four senior volunteers and 12 patients referred to our sleep disorders clinic were studied for two nights. On one night, recordings were done in the laboratory with a traditional polysomnogram and the portable home recorder. On another night, portable home recorders were used in the subjects' homes. Of 36 subjects, 42% had sleep apnea and 39% had nocturnal myoclonus. Intermethod correlations were highly significant for sleep apnea index, nocturnal myoclonus index, total sleep period (TSP), total sleep time (TST), and wake time after sleep onset (WASO). The portable home recorder detected sleep apnea on 100% of nights during which sleep apnea was diagnosed by polysomnogram. The labor-saving and cost-saving benefits of home recordings as well as the increased comfort, privacy, and convenience will make the portable home recording the preferred method for many research and clinical applications.

Aged↗
PubMed1996

Detection of intraoperative incidents by electronic scanning of computerized anesthesia records. Comparison with voluntary reporting.

BACKGROUND: The use of a computerized anesthesia information management system provides an opportunity to scan case records electronically for deviations from specific limits for physiologic variables. Anesthesia department policy may define such deviations as intraoperative incidents and may require anesthesiologists to report their occurrence. The actual incidence of such events is not known. Neither is the level of compliance with voluntary reporting. METHODS: Using automated anesthesia record-keeping with long-term storage, physiologic data were recorded every 15 s from 5,454 patients undergoing noncardiothoracic surgery. Recorded measurements of blood pressure, heart rate, arterial oxygen saturation, and temperature were electronically analyzed for deviations from defined limits. The computer system also was used by anesthesiologists to report voluntarily those deviations as intraoperative incidents. For each electronically detected incident: 1) the complete automated anesthesia record was examined by two senior anesthesiologists who, by consensus, eliminated case records with artifact or in which context suggested that the incident was not clinically relevant, and 2) the anesthesia information management system database was checked for voluntary reporting. RESULTS: In 473 automated anesthesia records, 494 incidents were found by electronic scanning of 5,454 automated anesthesia records. Sixty intraoperative incidents were eliminated, 25 due to artifact and 35 due to context. When the remaining 434 intraoperative incidents were checked for voluntary reporting, 18 (4.1%) matching voluntary reports were found. All intraoperative incidents that were reported voluntarily also were detected by electronic scanning. Based on a 10% sample, the sensitivity rate of electronic scanning was 97.2% (35/36), and the specificity rate was 98.4% (427/434). Among 413 cases with electronically detected intraoperative incidents, there were 29 deaths (7.0%), whereas there were only 79 deaths (1.6%) among 5,041 cases without incidents (chi 2 = 58.5, P < 0.001). CONCLUSIONS: The use of an anesthesia information management system facilitated analysis of intraoperative physiologic data and identified certain intraoperative incidents with high sensitivity and specificity. A low level of compliance with voluntary reporting of defined intraoperative incidents was found for all anesthesiologists studied. Finally, there was a strong association between intraoperative incidents and in-hospital mortality.

Anesthesiology↗
PubMed1994

Yield of sphenoidal recording in sleep-deprived outpatients.

We retrospectively reviewed the results of sphenoidal recordings performed after sleep deprivation in 101 consecutive outpatients whose prior scalp EEGs failed to show epileptiform discharges (EDs). These patients were suspected of having seizures of temporal lobe origin. Blinded reviews of the recordings by two electroencephalographers showed a tendency for sphenoidal recording to detect EDs at a higher rate than scalp recording, but the difference did not reach statistical significance (p = 0.06). However, EDs appeared exclusively at sphenoidal electrodes in 11 patients and exclusively at scalp electrodes in 3. The probability of detecting EDs with combined scalp and sphenoidal recordings was greater when spells were characterized by focal symptoms or signs. Except in three patients, initial EDs occurred during the first 30 min of recording. We recommend that post-sleep-deprivation recording be performed initially with scalp and other noninvasive electrodes (such as anterior temporal, ear, or cheek electrodes). If no EDs occur after 30 min, sphenoidal electrode insertion and recording may then be considered, especially in patients with spells characterized by focal signs or symptoms.

Adolescent↗
PubMed1992

Comparison of methods of assessing 24-hour intraesophageal pH recordings in children.

Prolonged intraesophageal pH recording, an important test in the evaluation of children with suspected gastroesophageal reflux (GER) disease, may be performed and evaluated by markedly different methodologies. Twenty-four-hour intraesophageal pH recordings from 67 consecutive infants were evaluated by three scoring methods: early postprandial, late postprandial, and total recording. In addition, the scoring methods were evaluated for their ability to identify 20 infants with clinically defined GER-induced acute life-threatening events (ALTEs). There were significant positive correlations between each pair of scoring systems (early postprandial with late postprandial, early postprandial with total recording, and late postprandial with total recording). However, our data indicate that the three methods identify different groups of patients. The early and late postprandial methods disagreed in designating "normal" versus "abnormal" in approximately 20% of patients. The total recording method was more likely to label patients as normal than either of the other methods; it yielded normal results in approximately one half of patients abnormal by either the early or the late postprandial methods. Patients with GER-induced ALTEs were identified by the early postprandial method in 90% of cases, the late postprandial method in 95% of cases, and the total recording method in only 45% of cases. By applying three different scoring methods to the same 24-h intraesophageal pH recording, we demonstrated less-than-perfect correlation among the methods. Long-term follow-up is needed to determine if these differences are of clinical significance. We feel that effort should be directed toward standardizing the approach to intraesophageal pH monitoring in infants.

Esophagus↗
PubMed1996

Validation of a flow-differential technique for the recording of splenic blood-volume changes to vasoactive agents.

Splenic blood-volume changes to norepinephrine were determined in the anesthetized cat by recording the integral of the difference between splenic arterial flow and splenic venous flow (flow-differential technique) with ultrasonic transit-time flowmeters, and the changes recorded with this technique were compared with those recorded with an independent technique, the gravimetric method. Norepinephrine (0.003-0.3 microgram/min/kg of body weight) induced dose-related decreases in splenic volume, and the values recorded by the flow-differential technique were not significantly different from those recorded with the gravimetric technique. The values recorded by the two methods were highly correlated (r = 0.86). The slope of the line plotting the relation between the two methods was close to unity (0.97 +/- 0.12), and the intercept of the line was close to zero (-0.46 +/- 1.6 ml). The results suggest that the recording of the flow differential between splenic arterial flow and splenic venous flow with ultrasonic transit time flowmeters is a valid method for the recording of splenic blood-volume changes to vasoactive agents.

Animals↗