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PubMed2000

Impact of different inspiratory flow patterns on arterial C02-tension.

Ventilation with decelerating inspiratory flow is known to reduce the dead space fraction and to decrease PaCO2. Constant inspiratory flow with an end-inspiratory pause (EIP) is also known to increase the removal of CO2. The aim of the study was to elucidate the effect of the pause/no-flow period while both the pattern and rate of inspiratory flow was unchanged, and when the lung was ventilated with sufficient PEEP to prevent end-expiratory collapse. Surfactant depleted piglets were assigned to decelerating or constant inspiratory flow with 24 breaths per minute (bpm) or 12 bpm, or to constant flow, without and with an end-inspiratory pause of 25%. By adding an EIP the total time without active inspiratory flow of the respiratory cycle was kept unchanged. Gas exchange, airway pressures, functional residual capacity (using sulfurhexafluoride) and haemodynamics (thermo-dye indicator dilution technique) were measured. Irrespective of ventilatory frequency, PaCO2 was lower and serial dead space reduced with decelerating flow, compared with constant inspiratory flow. With an end-inspiratory pause added to constant inspiratory flow, serial dead space was reduced but did not decrease PaCO2. The results of this study corroborate the assumption that total time without active inspiratory flow is important for arterial CO2-tension.

Animals↗
PubMed1998

GH dependence and GH withdrawal syndrome in GH treatment of short normal children: evidence from growth and cardiac output.

The child's age is a significant determinant of the outcome of GH therapy; prepubertal children respond better on both short term and long term growth, whereas adolescents tend to accelerate their bone maturation more than growth. The present study was designed to evaluate the efficacy of an interrupted GH therapy protocol of young, short normal children. GH was given for a period of 3 years, or until they reached the 25th percentile, then discontinued at a young age (not more than 9 years), and then the children's growth followed until final height. Yet, after discontinuation of GH therapy, growth came close to a complete stand-still. The present report focuses on describing the period beyond GH withdrawal and its impact on growth and cardiac performance. Twenty-two children received daily s.c. injections of 0.9 mg/m2 hGH and 12 children were the control, untreated group. Growth and echocardiography were followed during therapy and 2 years thereafter. During GH treatment growth velocity accelerated markedly over the first year; it slowed down over the second and third years, and decelerated after GH withdrawal to a velocity that was significantly lower than pretreatment values. Growth rate remained low for the next year, and recovered to pretreatment velocity by the fourth semiannual measurement. To evaluate the role of the GH-IGF-I axis during the growth deceleration, serum IGF-I, insulin-like growth factor-binding protein-3 (IGFBP-3), and an arginine stimulation test were performed at 1, 3 or 6 months after GH withdrawal, and compared with pretreatment response. GH response was 70% of pretreatment values by 1 month and recovered completely by 3 months post treatment. Serum IGF-I and IGFBP-3 levels were normal throughout. End-systolic and end-diastolic left ventricular dimensions as well as cardiac output did not change during the 2 year course of GH therapy, but fell significantly during the initial 6 months of GH withdrawal. Thus, daily injections of GH to prepubertal short normal children is associated with development of drug dependence, followed during the abstinence period by deceleration of growth and reduction of cardiac output to levels that are lower than pretreatment values. After GH therapy for 30-36 months the withdrawal syndrome persists for 18 months, and is not induced by alterations of serum levels of GH or IGF-I.

Body Height↗
PubMed1987

Role of CT in excluding major arterial injury after blunt thoracic trauma.

The role of CT in the diagnosis of major vascular rupture following blunt decelerating chest trauma is controversial. Its value in excluding major arterial injury has not yet been determined. During a 12-month period we obtained dynamic enhanced thoracic CT studies in 20 patients with blunt decelerating thoracic trauma who had abnormal or equivocal mediastinal contours on chest radiographs. In all cases diagnosis was confirmed by either digital subtraction (18 patients) or conventional thoracic angiography (two patients). CT scans showed evidence of direct aortic injury in three patients and evidence of mediastinal hematoma in five others. Four of these eight patients had major arterial injury verified angiographically and at surgery. In two patients the CT scan was considered equivocal; both patients had normal thoracic angiograms. CT excluded direct vascular injury or mediastinal hematoma in 10 patients. All 10 had normal thoracic angiograms. This preliminary study suggests that, in patients sustaining blunt decelerating thoracic trauma, thoracic CT may be more valuable than chest radiography in excluding major vascular injury and, in some cases, may reduce the need for thoracic angiography.

Adolescent↗
PubMed2006

Coronary flow velocity pattern assessed by transthoracic Doppler echocardiography predicts adverse clinical events and myocardial recovery after successful primary angioplasty.

BACKGROUND: Doppler guidewire studies demonstrated that specific velocity patterns in the left anterior descending coronary artery (LAD) after primary percutaneous coronary intervention (PCI) predict myocardial recovery and clinical outcome. The present study assessed whether similar results can be achieved by transthoracic Doppler echocardiography (TTDE). METHODS: Coronary flow velocities of LAD were evaluated by TTDE in 35 consecutive patients with anterior acute myocardial infarction who were treated with successful primary PCI plus stenting, performed within 6 h after the onset of symptoms or within 6-12 h if there was evidence of continuing ischaemia. Coronary-flow velocity of the LAD was achieved after 12 h and within 48 h after the PCI; TTDE standard examination was repeated after 2 months of follow-up. RESULTS: Three patterns were found: (i) 'pattern A' with good antegrade systolic flow and slow diastolic deceleration rate (63.7%); (ii) 'pattern B' with reduced or absent systolic flow and rapid diastolic deceleration rate (9.1%); and (iii) 'pattern C' with protosystolic retrograde flow and rapid diastolic deceleration rate (27.2%). The clinical characteristics and echocardiographic data were compared: wall-motion-score-index (WMSI), ejection fraction, end-diastolic volume (EDV) after PCI (T1) and after 2 months (T2). Patients with pattern A demonstrated recovery of contractile function (WMSI-T1 1.48 + or - 0.42/WMSI-T2 1.29 + or - 0.29, P < 0.05) and better clinical outcome; patients with patterns B and C ran into ventricular remodelling (EDV-T1 89 + or - 6.3 ml/EDV-T2 123 + or - 25 ml, P = 0.002) and more early and late complications. CONCLUSIONS: TTDE is a reliable method to achieve coronary flow velocities in LAD after an anterior acute myocardial infarction and it could be useful to evaluate no-reflow phenomenon at bedside and thus clinical outcome.

Aged↗
PubMed1976

Effects of incentive and preparatory interval on activity, heart rate, and reaction time in children.

To resolve certain empirical and theoretical difficulties concerning, primarily, the significance of phasic heart-rate deceleration prior to reaction signals, 48 children were employed to perform in simple reaction-time tasks while speed, heart rate, head movement, gross movement, and blink activity were recorded. The indeory intervals and level of incentives. Reaction time varied with incentive, with preparatory interval and mode of presentation. Phasic heart-rate deceleration varied with the intervals but not incentive or mode of presentation. There was little relation between deceleration and RT. Heart rate and somatic movement measures (especially of blinking) were roughly concordant at a group level but did not correlate.

Acoustic Stimulation↗
PubMed2001

Autonomic reactivity during viewing of an unpleasant film.

The effect of an aversive, high-arousing film on heart rate, respiratory sinus arrhythmia, and electrogastrographic activity (EGG) was investigated. Previous studies have indicated a larger heart-rate deceleration for visual stimuli depicting surgery or blood compared to neutral content, and this phenomenon is similar to the bradycardia observed in animals in response to fear. The heart-rate deceleration is clearly parasympathetically driven, and it is considered a general index of attention. An accurate index of cardiac vagal tone can be obtained by means of quantification of the amplitude of respiratory sinus arrhythmia. The relationship between cardiac vagal tone and EGG is complex, but animal research has shown that suppressing vagal activity dampens gastric motility. We have investigated whether a movie depicting surgery is associated with greater heart-rate deceleration, larger increase in respiratory sinus arrhythmia, and greater increase in EGG activity compared to a neutral movie. In addition, if both respiratory sinus arrhythmia and EGG are indices of vagal tone, a positive correlation between these physiological responses was expected. Analysis indicated an effect of the surgery movie on heart rate and respiratory sinus arrhythmia, but not on EGG activity. Moreover, the expected correlation was not found. Implications for future studies are discussed.

Adult↗
PubMed1995

The effect of velocity and gender on load range during knee extension and flexion exercise on an isokinetic device.

Limb acceleration and deceleration during exercise on an isokinetic device encounter no machine-offered resistance. The purpose of this study was to quantify the relationship between velocity and range of motion that is sustained at a predetermined isokinetic velocity, termed load range, during concentric knee extension and flexion exercise. Nine male and nine female subjects performed three maximal concentric reciprocal knee extension and flexion repetitions at 60, 120, 180, 240, 360, and 450 degrees/sec. Extension and flexion results revealed a significant (p < 0.05) increase in acceleration and deceleration range of motion while load range significantly decreased with increasing velocity. Males exhibited greater load range and less acceleration range of motion than females at 240, 360, and 450 degrees/sec, while deceleration range of motion was not different between genders at any speed. These results demonstrate an inverse relationship between isokinetic velocity and load range and suggest a need to carefully consider velocity selection when performing exercise on an isokinetic device.

Adult↗
PubMed2002

A study of antagonist/agonist isokinetic work ratios of shoulder rotators in men who play badminton.

STUDY DESIGN: Normative descriptive study. OBJECTIVES: Exploring the isokinetic work ratios of eccentric antagonist/concentric agonist shoulder rotators in the late cocking and deceleration phases of a forehand overhead smash in badminton players. Comparing the work ratios between dominant and nondominant shoulders. BACKGROUND: The strength of shoulder muscles for badminton players has been studied but there is little information on the work output of these muscles for a specific range of movement. METHODS AND MEASURES: Twenty-five skilled men who play badminton at club level with a mean age of 29.4 years (SD = 6.1) were measured for concentric and eccentric isokinetic work (joules) of shoulder internal (IR) and external (ER) rotators on both upper extremities at 120 degrees/s. Bilateral isokinetic work ratios for eccentric IR/concentric ER between 60 degrees and 90 degrees of shoulder external rotation were calculated to denote strength profile in the late cocking phase of the badminton smash. Work ratios for eccentric ER/concentric IR between 10 degrees external rotation and 30 degrees internal rotation were calculated to denote strength profile in the deceleration phase of the badminton smash. The respective work ratios were compared between both shoulders. RESULT: The eccentric IR/concentric ER work ratios in late cocking were 1.9:1 and 1.3:1 (P = 0.001) for the dominant and nondominant shoulders, respectively. The eccentric ER/concentric IR work ratios in the deceleration phase were 1.1:1 and 1.3:1 (P = 0.003) for the dominant and nondominant shoulders, respectively. CONCLUSION: The work ratios of eccentric antagonist/concentric agonist are different between dominant and nondominant shoulders of skilled badminton players. Rehabilitation for injuries of these athletes should aim at developing the optimal antagonist/agonist work ratios to return them to this sport.

Adult↗
PubMed1980

Correlation of fetal heart rate patterns with umbilical artery pH and catecholamines during last hour of labor.

Fetal heart rate (FHR) patterns were analysed during last hour of labour and correlated to umbilical artery pH and catecholamine (CA) levels. Fetuses with pathological FHR had significantly higher levels of CA than those with normal FHR. Particulary high levels were found in fetuses with bradycardia and late decelerations. FHR was further analysed by a computer (DPAC, data processor and computer) in 100 women during last hour of labor. No correlation between deceleration areas of variability and umbilical artery pH and CA was found. It is concluded that although there is a good correlation between the general FHR-pattern and umbilical artery CA and pH it is impossible to quantify the degree of fetal distress by calculation of deceleration areas and variability.

Catecholamines↗
PubMed1986

Heart frequency of the fetus at birth.

Heart frequency was recorded in 10 infants during the delivery and the following day. It was found that during vaginal birth, in cephalic presentation, heart frequency decreased during the last 3 minutes before delivery of the head. In breech presentation the initial deceleration was shorter, while with cesarean section there was no initial deceleration. Shortly after delivery of the head and in close connection with the first cry, a tachycardia lasting approx. 10 minutes was observed in all infants. On the day after birth, all infants had a normal heart frequency. It is concluded that the heart frequency changes correspond to the alterations expected on the basis of the caput compression and the relative fetal hypovolemia arising during the final stage of the vaginal delivery. These observations also indicate that the variable deceleration is caused partly by fetal hypovolemia. The neonatal tachycardia is presumably a response to the ordinary placental transfusion and neonatal adaptation to extra-uterine life.

Blood Pressure↗
PubMed1988

Rotatory test in otoneurology.

A series of rotatory tests are described, by which it is possible to activate the ocolomotor system by visual as well as by vestibular stimuli, either separately or in combination. The visual-oculomotor system was studied by means of rotation with 10 degrees constant speed for 10 s in either direction. Pursuit movements and saccades were also studied. The vestibulooculomotor system was studied by acceleration behind closed eyes with 10 degrees/s2 up to 100 degrees, immediately followed by a similar deceleration. Normal and pathological cases are presented. A combined visual-vestibular stimulation was performed with the same kind of acceleration-deceleration but with eyes open. Acceleration demonstrated the summation effect of visual and vestibular input to the vestibular nuclei. The deceleration revealed the cerebellar ability to suppress the vestibular output. Normal and pathological cases are demonstrated. Finally, a combined rotation was introduced, informing us about the vestibular reaction, the visual-vestibular summation, the optokinetic reactions, and the cerebello-vestibular suppression. Normal and pathological cases are described.

Acceleration↗
PubMed1989

Visual acceleration detection: effect of sign and motion orientation.

Thresholds for the detection of constant acceleration and deceleration of a discrete object moving along horizontal and vertical axes were studied. A staircase methodology was used to determine thresholds for three average velocities (0.7, 1.2, and 1.7 deg/sec). Thresholds, expressed as the proportion of velocity change, did not differ significantly among the average velocities; thus, a consistent Weber-like fraction is suggested by the data. Furthermore, there was an interaction between the axis of motion (horizontal or vertical) and the sign of the velocity change (acceleration or deceleration): accelerations were easier to detect along the vertical axis, decelerations along the horizontal axis.

Acceleration↗
PubMed2005

A sonographic assessment of different patterns of placenta previa "migration" in the third trimester of pregnancy.

OBJECTIVE: The purpose of this study was to compare the rates and patterns of placental "migration" with the mode of fetal and placental delivery and the incidence of peripartum complications. METHODS: This was a retrospective study of 163 cases of placenta previa diagnosed by transvaginal sonography at 28 weeks' gestation that were followed serially by sonography. The patients were stratified into 3 groups depending on the placenta-to-internal cervical os distance: (1) an overlap of 0.0 cm or greater over the cervical os, (2) 0.1 to 2.9 cm, and (3) 3.0 cm or greater. The mean rate of placental migration (millimeters per week) was obtained at 28 to 32 and 32 to 36 weeks' gestation. A pattern of placental migration was classified as one with acceleration or deceleration of the placental migration in the late third trimester based on a comparison between the migration rates at 28 to 32 and 32 to 36 weeks' gestation. RESULTS: At the time of delivery, 22, 29, and 112 patients were included in groups 1, 2, and 3, respectively. The rates of placental migration correlated with the final placental distance from the internal cervical os (0.1 to 4.1 mm/wk for groups 1 and 3, respectively). Significantly higher rates of interventional cesarean delivery (CD) (P=.0002), elective CD (P=.0254), manual placenta removal (P=.0419), and placenta accreta (P=.0039), but not CD for indications other than placenta previa (P=.0752), were associated with a placental distance of less than 2.0 cm away from the cervix and a deceleration pattern of placental migration. In contrast, vaginal delivery was significantly associated with a placental distance of 2.0 cm or greater away from the cervix and an acceleration pattern of placental migration (P=.0034). CONCLUSIONS: A final placental distance of less than 2.0 cm from the internal cervical os and a deceleration pattern of placental migration were significantly associated with an interventional CD and a higher rate of peripartum complications.

Delivery, Obstetric↗
PubMed1999

[Evaluation of restenosis after percutaneous transluminal coronary angioplasty using a Doppler index, the Tei index].

Cardiac function and restenosis were evaluated after percutaneous transluminal coronary angioplasty (PTCA) using a Doppler index (the Tei index). Thirty-eight patients, 31 men and 7 women (mean age 57 years) with ischemic heart disease were studied. The underlying heart diseases were angina pectoris without left ventricular asynergy in 16 patients and old myocardial infarction (OMI) with left ventricular asynergy in 22 . Ejection fraction was measured by M-mode echocardiography and deceleration time, and the interval between cessation and onset of the mitral inflow velocity (a), ejection time at aortic valve (b), and the Tei index [(a-b)/b] were measured by M-mode echocardiography performed before and 6 months after PTCA. The ejection fraction, deceleration time and Tei index showed no changes after PTCA in patients with angina pectoris with or without restenosis. In patients with OMI with restenosis, the Tei index increased slightly after PTCA, from 0.56 +/- 0.15 to 0.61 +/- 0.13. The deceleration time changed from 0.23 +/- 0.03 to 0.24 +/- 0.02 msec, and the ejection fraction from 0.46 +/- 0.11 to 0.51 +/- 0.17, neither significantly. However, in patients with OMI without restenosis (15 out of 22 patients), the Tei index significantly improved after PTCA, from 0.55 +/- 0.13 to 0.48 +/- 0.12 (p < 0.05). In patients with left ventricular asynergy due to old myocardial infarction, without restenosis, the Tei index significantly improved after PTCA. The Tei index is useful for evaluating restenosis after PTCA in patients with OMI.

Angina Pectoris↗
PubMed1999

[Amnio-infusion during labor: experience and review of the literature].

OBJECTIVES: Evaluation of amnioinfusion results during labour in case of thick meconial amniotic fluid or in case of oligo-hydramnios associated with variable deceleration of the fetal heart response. PATIENTS AND METHODS: Prospective non randomized study. Amnioinfusion was applied to 47 cases of thick meconial amniotic fluid and to 18 cases of variable fetal heart decelerations associated with oligo-hydramnios. Obstetrical and neonatal data were compared with a similar group without amnioinfusion (n = 32). RESULTS: Comparing both groups shows that amnioinfusion offers a better fetal well-being during labour, according to Kreb's fetal heart evaluation during labour (8.53 +/- 1.06 vs 6.56 +/- 0.35--p < 0.01), lows the cesarean section rate (8.5% vs 31.2%--p < 0.01). Amnioinfusion is also associated with a higher Apgar's score at one minute after delivery (9.4 +/- 0.8 vs 8.7 +/- 1.7--p = 0.01) and a lower rate of thick meconium inhalation (13.7% vs 40.7%--p < 0.01). There was no difference for children's first days of life. We found no serious complication following amnioinfusion. CONCLUSION: We confirm general agreement about amnioinfusion, according to international literature. Amnioinfusion needs an acute care to prevent classically described complications. In case of thick meconial amniotic fluid or variable decelerations associated with oligo-hydramnios, amnioinfusion during labour offers a better fetal well-being.

Adult↗
PubMed1999

Doppler echocardiographic study of left and right ventricular function during dobutamine stress testing in conscious healthy dogs.

OBJECTIVE: To evaluate left and right ventricular filling and ejection performances by use of Doppler echocardiography in healthy, conscious dogs submitted to dobutamine stress testing. ANIMALS: 10 unsedated, healthy adult Beagles. PROCEDURE: Doppler echocardiography was performed during cardiac stress testing on each dog twice at 24-hour intervals. Dobutamine was infused in 10 micrograms/kg of body weight/min incremental dosages, from 12.5 to 42.5 micrograms/kg/min. Duration of each step was 15 minutes. Doppler measurements were recorded at baseline and at each stage of dobutamine infusion, whereas aortic diameter was measured at baseline and at peak dosage by use of two-dimensional echocardiography. RESULTS: Dobutamine infusion induced a significant increase in velocity time integrals and in peak flow velocities at the aortic, pulmonic, mitral, and tricuspid valves. Acceleration time-to-deceleration time ratio at the aortic wave also was increased significantly. On the other hand, ejection time, acceleration time, and deceleration time at the aortic and pulmonic valves and peak flow velocity of the E wave-to-peak flow velocity of the A wave ratio at the mitral and tricuspid valves decreased significantly during the test. The acceleration time-to-deceleration time ratio at the pulmonic wave was unchanged. A significant, progressive increase in cardiac index also was observed during dobutamine infusion, with a maximal increase of 104% from baseline. This was mediated initially by an increase in stroke index and, at higher dosages, by an increase in heart rate. CONCLUSIONS AND CLINICAL RELEVANCE: Doppler echocardiography performed during dobutamine stress testing may be a reliable method of assessing myocardial function in dogs with cardiovascular disease.

Animals↗
PubMed1999

Frequency-dependent PSP depression contributes to low-pass temporal filtering in Eigenmannia.

This study examined the contribution of frequency-dependent short-term depression of PSP amplitude to low-pass temporal filtering in the weakly electric fish Eigenmannia. Behavioral and neurophysiological methods were used. Decelerations of the electric organ discharge frequency were measured in response to continuous and discontinuous electrosensory stimuli. Decelerations were strongest (median = 4.7 Hz; range, 3.5-5.9 Hz) at continuous beat rates of approximately 5 Hz and weakest (median = 0.4 Hz; range, 0.0-0.8 Hz) at beat rates of 30 Hz. Gating 20 or 30 Hz stimuli at a rate of 5 Hz, however, elicited decelerations that were sixfold greater than that of continuous stimuli at these beat rates (median = 2.6 Hz; range, 2.0-4.7 Hz for 30 Hz). These results support the hypothesis that short-term processes enhance low-pass filtering by reducing responses to fast beat rates. This hypothesis was tested by recording intracellularly the responses of 33 midbrain neurons to continuous and discontinuous stimuli. Results indicate that short-term depression of PSP amplitude primarily accounts for the steady-state low-pass filtering of these neurons beyond that contributed by their passive and active membrane properties. Previous results demonstrate that passive properties can contribute up to 7 dB of low-pass filtering; PSP depression can add up to an additional 12.5 dB (median = 4.5). PSP depression increased in magnitude with stimulus frequency and showed a prominent short-term component (t(1) = 66 msec at 30 Hz). Initial PSP amplitude recovered fully after a gap of 150 msec for most neurons. Remarkably, recovery of PSP amplitude could be produced by inserting a brief low-temporal frequency component in the stimulus.

Animals↗
PubMed2000

Fetal discrimination of low-pitched musical notes.

Cardiac responses of 36- to 39-week-old (GA) fetuses were tested with a no-delay pulsed stimulation paradigm while exhibiting a low heart rate (HR) variability (the HR pattern recorded when fetuses are in the 1f behavioral state). We examined whether fetuses could discriminate between two low-pitched piano notes, D4 (F(0) = 292 Hz/292-1800 Hz) and C5 (F(0) = 518 Hz/518-300 Hz). Seventy percent of all fetuses reacted to the onset of the first note (D4 or C5) with the expected cardiac deceleration. After heart rate returned to baseline, the note was changed (to C5 or D4, respectively). Ninety percent of the fetuses who reacted to the note switch did it with another cardiac deceleration. Control fetuses, for whom the first note did not change, displayed few cardiac decelerations. Thus, fetuses detected and responded to the pulsed presentation of a note and its subsequent change regardless of which note was presented first. Because perceived loudness (for adults) of the notes was controlled, it seems that the note's differences in F(0) and frequency band were relevant for detecting the change. Fetuses' ability to discriminate between spectra that lay within the narrow range of voice F(0) and F(1) formants may play an important role in the earliest developmental stages of speech perception.

Adult↗