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PubMed1977

The association of umbilical cord complications and variable decelerations with acid-base findings.

Variable decelerations during the last 2 hours of labor were associated with an abnormally positioned umbilical cord at delivery in 52% of cases. In cases where an abnormally positioned umbilical cord was seen at delivery, 89% had been preceded by variable decelerations. Cord compression resulted in an A-V difference in pH that was significantly increased when compared to a control group. This was mainly due to a decrease in the pH of the umbilical artery. The pathophysiology of cord compression is discussed.

Acid-Base Equilibrium↗
PubMed1992

Short-term fetal heart rate variation, decelerations, and umbilical flow velocity waveforms before labor.

OBJECTIVE: To determine the value of computerized antepartum measurements of short-term fetal heart rate (FHR) variation and decelerations as a predictor of outcome, and to compare these with measurements of the umbilical artery flow velocity waveform. METHODS: Data were collected from 3563 high-risk patients for measurements of FHR variables (15,702 records) and outcome (intrauterine death or metabolic acidemia on delivery). Detailed analyses were made on 89 patients with one or more records in which short-term FHR variation was 3 milliseconds or less. Umbilical artery flow velocity waveforms were measured concurrently on 2441 occasions in 991 patients. RESULTS: More than half of the patients with FHR variation of 3 milliseconds or less were identified before 31 weeks. When short-term FHR variation exceeded 3 milliseconds, there were no intrauterine deaths and only one instance of metabolic acidemia on cesarean delivery. When FHR variation fell below 2.6 milliseconds, 34% of the subjects had metabolic acidemia on cesarean or intrauterine death. The appearance or absence of decelerations was an unreliable guide to outcome. The correlation between FHR variation and the umbilical artery flow velocity waveform was low (r = 0.32). The population studied contained some patients without placental vascular disease or, in five with pre-eclampsia, without abnormal umbilical artery velocity waveforms but with grossly reduced FHR variation. CONCLUSION: Reduction in short-term FHR variation, as measured by computer, reliably predicts fetal outcome and is a more general measure of fetal well-being than are umbilical artery flow velocities.

Blood Flow Velocity↗
PubMed1992

Changes of pulsatility index from fetal vessels preceding the onset of late decelerations in growth-retarded fetuses.

Thirty-six growth-retarded fetuses selected from a population of 214 cases were studied by Doppler ultrasonography at weekly intervals for at least 4 weeks between the diagnosis of Doppler abnormalities suggestive of the existence of the brain-sparing effect (ie, ratio between umbilical artery and middle cerebral artery pulsatility indexes [PIs] above the 95th percentile of our reference limits) to the onset of antepartum late fetal heart rate (FHR) decelerations. Recordings were made from the umbilical artery, descending aorta, renal artery, internal carotid artery, and middle cerebral artery and the PIs were calculated. Statistically significant changes in PI occurred in all the vessels studied. However, different trends were found when the modifications in cerebral vessels were compared with those in fetal peripheral vascular beds and in the umbilical artery. In cerebral arteries, a nadir of vasodilatation was reached 2 weeks before the onset of antepartum late FHR decelerations, whereas significant changes in the peripheral and umbilical vessels occurred close to the onset of abnormal FHR patterns. This study demonstrates that despite a brain-sparing effect, there are further Doppler-detectable modifications in fetal circulation that differ between the cerebral and peripheral vascular beds.

Cerebrovascular Circulation↗
PubMed2004

Gunshot residue particle velocity and deceleration.

The velocity of over 800 gunshot residue particles from eight different sources was determined using high speed stroboscopic photography (spark gap light source). These particles were found to have an average velocity of 500 to 600 ft per second. Many particles acquired considerably higher velocities. Thus, the particles have sufficient energy to embed themselves within certain nearby targets like skin or fabric. The relatively high velocity that the particles acquire explain the formation of stippling on skin in close proximity to a muzzle discharge. These findings also indicate little influence of air currents on particle behavior near the muzzle. The deceleration of less than 100 particles during a 100-microsecond interval was also calculated. The particles experienced rapid rates of deceleration which would explain why few particles are found in test firings beyond 3 ft from the muzzle of a discharged firearm. Because of their relatively high velocity, normal wind velocity would not be expected to significantly influence their motion near the muzzle.

Journal Article↗
PubMed1978

Growth deceleration patterns in children with constitutional short stature: an aid to diagnosis.

A retrospective study of 263 children referred for evaluation of short stature revealed that 149 (56.7%) had constitutional short stature (CSS). A typical pattern of growth was observed in these children. As exemplified by 12 children who had complete serial growth measurements, exaggerated growth deceleration first became apparent between 3 and 6 months of age, was greatest in the first two years of life, and resulted in these children falling more than 2 SDs below the mean for height by 3 years of age. After 3 years of age, the growth rate of these children with CSS was essentially the same as that of normal children, and they ran parallel to the growth curve though below the third percentile. The importance of serial measurements and the growth chart is emphasized, and recommendations are made for the evaluation of short stature or abnormal growth deceleration in the first three years of life. Awareness of this typical pattern of growth in children without disease may aid the pediatrician in his evaluation of short stature and allow for watchful waiting when results of screening tests are normal.

Age Determination by Skeleton↗
PubMed1989

Increased placental resistance and late decelerations associated with severe proteinuric hypertension predicts poor fetal outcome.

The flow velocity wave forms generated by Doppler ultrasound examination of the umbilical artery were correlated with fetoplacental blood flow and numerically expressed as a ratio between the systolic (A) and the end-diastolic point (B). The technique is non-invasive and simple to perform. A cohort analytical study was done to see whether useful information could be obtained from the A/B ratio that could help in the management of patients with severe proteinuric hypertension. Fifty patients with severe proteinuric hypertension at less than 34 weeks' gestation were studied and serial Doppler ultrasound examinations of the umbilical artery were performed. No ultrasound results were made available to the clinician. An A/B ratio of 6 or greater was regarded as increased. Twenty-eight of the patients had an increased A/B ratio; in this group these 14 infants were small for gestational age, 14 developed late decelerations and there were 12 perinatal deaths. The remaining 22 patients had an A/B ratio of less than 6 and only 3 produced infants which were small for gestational age; 2 fetuses developed late decelerations and there was 1 perinatal death. A significant difference was found between the two groups in respect of these results. The group with an abnormal A/B ratio also experienced more neonatal morbidity. The A/B ratio of the umbilical artery wave form may assist in planning delivery of patients with severe proteinuric hypertension more accurately.

Blood Flow Velocity↗
PubMedDate not supplied

[Examination of the reduction of umbilical circulation in fetuses with variable decelerations of heart rate using Doppler sonography of the umbilical artery].

4 patients with ruptured membranes and spontaneous labour showed variable decelerations of the fetal heart rate. Blood flow velocities of the umbilical arteries were measured by means of pulsed Doppler ultrasound. The flow velocity waveforms, being normal between the contractions, showed a rapid change to absent and reverse diastolic flow during uterine contraction. By means of quantitative estimation the forward flow as as high as the measured reverse flow in the umbilical artery, resulting in a stop of placental perfusion. Computer-added reconstruction of the curve of fetal heart frequency revealed the exact temporal relation between reduction of umbilical artery perfusion and deceleration of fetal heart rate as well as the relation between recovery of the fetal heart rate and normalisation of blood flow in the umbilical artery. Using this noninvasive method, we could analyze for the first time the acute changes of umbilical artery perfusion in relation to changes of the fetal heart rate in human fetus. A stop in placental perfusion does not always mean an absence of any movement of the fetal blood column. We could demonstrate that this is due to a systolic forward and diastolic reverse flow in the same extent. The described acute flow alterations are discussed as a model for flow alterations described in high risk pregnancies with abnormal fetoplacental perfusion.

Blood Flow Velocity↗
PubMed1979

[Cardiovascular changes of the foetal circulation during deceleration in acute foetal hypoxia (author's transl)].

Acute foetal hypoxia trials were conducted in 11 foetuses of sheep. The following parameters were determined continuously besides heart rate, art. pO2, arterial and venous blood pressure: cardiac output, stroke volume and system resistance. Acute foetal hypoxia was produced in two ways: 1) Compression of the maternal vena cava The arterial blood pressure in the foetus is increased. This is reflected mainly by the systolic blood pressure. This increase is provoked by the increase in stroke volume (up to 100%). This increase in stroke volume is so great that the cardiac output is increased despite the onset of deceleration. The system resistance remains unchanged. 2) Maternal hypoxia In contrast to foetal hypoxia as described above, the increase of stroke volume is not so pronounced at the onset of deceleration, and the system resistance is increased. After termination of maternal hypoxia there is an abrupt change of system resistance back to the original value. Both types of foetal hypoxia will subsequently not differ significantly from each other.

Acute Disease↗
PubMed2001

Age-related differences in postural control in humans in response to a sudden deceleration generated by postural disturbance.

Age-related differences in postural control in response to a relatively large deceleration resulting from postural disturbance were investigated in eight normal elderly men (age range 67-72 years) and eight young men as controls (age range 19-22 years) using a moving platform. Data were obtained for the hip, knee and ankle angles, position of the centre of foot pressure (CFP), head acceleration, and muscle activity of the leg muscles. The elderly subjects had slower and larger ankle and hip joint movements, and CFP displacement in response to the disturbance compared to the young controls. The elderly subjects also had a delayed occurrence, and greater magnitude of peak acceleration of head rotation than did the young subjects. For the elderly subjects, the CFP was closely related to angular changes in the hip joint movement, but not to those of the ankle and knee joint movements. For the young subjects, on the other hand, the CFP was significantly correlated with angular change in the ankle joint. Cocontraction of the tibialis anterior and gastrocnemius muscles was observed in the elderly subjects. The results indicated that a movement pattern for postural correction in the elderly adults was different from that of the young adults. The elderly relied more on hip movements while the young controls relied on ankle movements to control postural stability.

Adult↗
PubMedDate not supplied

Azygos vein laceration following a vertical deceleration injury.

A 41-year-old man presented with respiratory distress and hypotension after a 30-foot fall from a tree. Despite fluid resuscitation, the patient expired in the operating room. Autopsy revealed an azygos vein laceration at the junction of the superior vena cava as the cause of death. Azygos vein and superior vena caval lacerations are rare following blunt chest trauma, including vertical deceleration injury. Early suspicion of vascular injuries with aggressive fluid resuscitation and surgical intervention remain the only hope for survival from this highly lethal injury.

Accidental Falls↗
PubMed1999

Noninvasive evaluation of pulmonary capillary wedge pressure in patients with acute myocardial infarction by deceleration time of pulmonary venous flow velocity in diastole.

OBJECTIVES: This study investigates the correlation between deceleration time of diastolic pulmonary venous flow (PV-DT) and of early filling mitral flow (LV-DT), and pulmonary capillary wedge pressure (PCWP) in patients with acute myocardial infarction (AMI). BACKGROUND: An earlier study suggests that Doppler-derived LV-DT provides an accurate means of estimating PCWP in postinfarction patients with left ventricular systolic dysfunction. Furthermore, recent studies have suggested that PCWP correlates better with PV-DT than with LV-DT. However, the value of PV-DT and LV-DT for assessment of PCWP in patients with AMI has not been evaluated. METHODS: In 141 consecutive patients with AMI, we measured PV-DT and LV-DT by Doppler echocardiography, and compared these variables with PCWP measured using a Swan-Ganz catheter. RESULTS: There was a weak negative correlation between the LV-DT and PCWP (r = -0.54). Although the sensitivity of < or =130 ms in LV-DT in predicting > or =18 mm Hg in PCWP was high (86%), its specificity was low (59%). On the other hand, a very close negative correlation was found between PV-DT and PCWP (r = -0.89). The sensitivity and specificity of < or =160 ms in PV-DT in predicting > or =18 mm Hg in PCWP were 97% and 96%, respectively. CONCLUSIONS: In patients with AMI, Doppler-derived PV-DT showed a stronger correlation with PCWP than LV-DT.

Adult↗
PubMed1998

Acceleration-deceleration injuries to the brain in blunt force trauma.

Blunt force trauma to the stationary head is generally associated with cortical-subcortical injuries located at the site of impact (i.e., coup contusions). We present 2 cases of cerebral contusion injury secondary to falling tree limbs hitting the head, illustrating an exception to this observation. In each case, the most prominent lesions were white matter hemorrhagic contusions similar to those associated with acceleration-deceleration types of injuries characterizing falls or motor vehicle accidents (i.e., contrecoup contusions). The proposed pathogenesis for these observed lesions is a forceful impact resulting in the acceleration of the head and brain of a magnitude comparable with that in a motor vehicle accident or a fall.

Acceleration↗
PubMed2002

Progressive electroencephalogram frequency deceleration despite constant depth of propofol-induced sedation.

OBJECTIVE: To investigate a possible time-dependent effect of propofol sedation on electroencephalographic activity, we analyzed the electroencephalogram frequency behavior while keeping patients at a constant level of sedation. DESIGN: Prospective, controlled trial. SETTING: Intensive care unit of a university hospital. PATIENTS: Twenty patients without neurologic or metabolic disorders. MEASUREMENTS AND MAIN RESULTS: During sedation with propofol (1-4 mg x kg(-1) x hr(-1)), a bifrontally recorded processed electroencephalogram was obtained. For 48 hrs, sedation was kept constant at a level according to Ramsay Scale 3 while we adjusted the dosage of propofol given per hour. At hours 6, 18, 30, and 42, blood samples were taken to assess the plasma concentration of propofol. The electroencephalogram values of 60 mins obtained during 1 hr before blood sampling were taken for further calculation. From the data, relative band power of the beta-, alpha-, theta, and delta-bands, spectral median frequency, and spectral edge frequency 90 and 95 were computed. For statistical analysis, a polynomial three-factorial repeated-measures analysis of variance with covariates was performed. Relative power of beta- and alpha-wavebands showed a constant and significant decrease over time (beta, 15.5%, 10.3%, 10.3%, 7.6%; alpha, 14.8%, 13.4%, 10.0%, 8.3%), whereas relative delta power increased (delta, 56.4%, 63.4%, 70.7%, 72.3%). The theta-waveband remained unchanged. Accordingly, spectral edge frequency 90 and 95 and spectral median frequency decreased significantly. From hours 6 to 18, a significant increase of the plasma propofol concentration was found. Subsequently, the level remained constant. CONCLUSION: Despite constant sedation, a longer period of propofol application induces a time-dependent electroencephalogram frequency deceleration. The use of electroencephalogram derivatives to monitor depth of sedation in the intensive care unit thus should be regarded cautiously.

Adult↗
PubMed1990

Rupture of the supradiaphragmatic inferior vena cava by blunt decelerating trauma: case report.

Lacerations of the inferior vena cava resulting from blunt external trauma are relatively rare, but extremely serious. The high lethality is due to the difficulty in diagnosis and technical problems with repair, particularly if the injury is located above the renal veins. During a 12-month period seven patients with inferior vena cava laceration were seen, of whom two presented with laceration of the inferior vena cava above the diaphragm. Both had a deceleration injury while wearing seatbelts. The clinical presentation was similar. The etiology is discussed. Caval continuity should be repaired because acute sudden occlusion at the suprahepatic level is incompatible with survival. Median sternotomy is advised, moreover it provides good exposure for eventual cannulation.

Adult↗
PubMed2003

Assessment of wheelchair drag resistance using a coasting deceleration technique.

OBJECTIVE: To apply a recently developed coasting deceleration method to measure rolling and aerodynamic resistances opposing wheelchair propulsion on a variety of different wheelchairs and wheel combinations and on two different ground surfaces. DESIGN: For each condition, 20-25 trials were performed across a speed range of approximately 70-300 m/min. The least-squares method was then used to arrive at values for the coefficient of rolling resistance (CR) and effective frontal area of the wheelchair and occupant. RESULTS: Wheelchair rolling resistance was found to be velocity dependent under some circumstances. CR values on linoleum differed among folding lightweight wheelchairs and when compared with a rigid ultralight and racing wheelchair. Changing rear wheels and tires on one wheelchair resulted in a 14% difference in CR. Carpet increased CR values by an average of 0.0118 over the values determined on linoleum. As expected, effective frontal area of the wheelchair and occupant values were lower for the racer than for the folding lightweight wheelchair. CONCLUSIONS: Wheelchair rolling resistance is not always independent of velocity, and CR on linoleum can vary among wheelchairs by as much as seven-fold, and carpet can more than double CR.

Deceleration↗
PubMed2006

Biomechanic study of the human liver during a frontal deceleration.

BACKGROUND: Mechanisms of hepatic injury remain poorly understood. Surgical literature reports some speculative theories that have never been proved. The aim of this study was to examine the behavior of the liver during brutal frontal deceleration. METHODS: Six trunks, removed from human cadavers, underwent free falls at 4, 6, and 8 meters per second (mps). Accelerometers were positioned in the two lobes of the liver, in front of the vertebra L2, and in the retro hepatic inferior vena cava. Relative motions of the lobes of the liver and of the two other anatomic marks were observed. In parallel, numerical simulations of this experiment have been performed using a finite element model. RESULTS: In the direction of impact, the vertebra L2 had no considerable displacement with the inferior vena cava. There was a noteworthy displacement between the two hepatic lobes. The left hepatic lobe had a large relative displacement with the vertebra L2 and the inferior vena cava. The right hepatic lobe was more stable with the vertebra L2 and the inferior vena cava. Numerical simulation of the same protocol underlined a rotation effect of the liver to the left around the axis of the inferior vena cava. CONCLUSIONS: These results support the surgical data. They highlight a crucial zone and explain how dramatic lacerations between the two lobes of the liver can occur.

Aged↗
PubMed1995

Subintimal hematoma of the aorta after deceleration injury.

Deceleration injuries of the aorta may occur without aortic disruption. We describe the case of a patient with a subintimal hematoma of the aorta that resolved within 48 hours. Serial arteriography confirmed the diagnosis and excluded aortic rupture. Thoracic exploration was not performed.

Adult↗