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PubMed1987

Relationships between the type A behavior pattern and phasic heart rate responses during a reaction time task.

Type A and B college students performed a signalled reaction time task with a 17-s fixed preparatory internal (PI) while heart rate was recorded. The analysis of the first half of the PI indicated a triphasic heart rate response (deceleration-acceleration-deceleration) to the warning signal, followed by a return toward baseline. No group differences were found. During the latter half of the PI, the Type B subjects exhibited a time-locked heart rate deceleration which reached its maximum at the second immediately prior to the onset of the imperative stimulus. The Type A subjects exhibited maximum deceleration earlier in the PI. These findings are consistent with previous work indicating that Type A's have difficulty maintaining their attention over relatively long PI's of reaction time tasks.

Adult↗
PubMed1988

Effects of caffeine withdrawal on motor performance and heart rate changes.

Heavy caffeine Users and Non-users were tested twice using a signalled reaction time paradigm, while heart rate was recorded. During the 7-day interval between the two sessions, the User group maintained normal caffeine intake for the first 5 days and abstained from caffeine during the last 2 days, which constituted a withdrawal period. The Non-users abstained from caffeine (as they usually do) during the entire 7-day period. The analyses of the reaction time (RT) data indicated no differences during Session 1 and a significant group difference during Session 2, with the Non-users exhibiting faster RT's. The Users exhibited no change between Sessions 1 and 2, while the Non-users showed a decrease in RT's (increased speed) across Sessions, which may be indicative of a practice effect. The analysis of the heart rate data from the 5-s period prior to the imperative stimulus yielded no differences during Session 1, and a significant group difference in Session 2, with the Non-users exhibiting larger decelerations. Across the two Sessions, the Non-users showed an increase in the magnitude of the heart rate deceleration, while the Users exhibited a decline in the size of the deceleration. Since the magnitude of heart rate deceleration has been interpreted as an index of attention, it appears that the Users were exhibiting less efficient attention during withdrawal from caffeine (Session 2) than were the Non-users. This conclusion is supported by the RT data, showing slower response times for the Users during Session 2, as compared to Non-users.

Adult↗
PubMed1994

Physiological significance of the defense response to intense auditory stimulation: a pharmacological blockade study.

This paper examines through pharmacological blockade some questions related to the physiological significance of the defense response to intense auditory stimulation. Nine subjects received intravenous metoprolol (10-15 mg i.v.), intravenous atropine (0.03 mg/kg i.v.), or a saline solution as placebo condition before undertaking a test of the defense response to a distorted sound of 400 Hz frequency, 109 dB intensity, 0.5 sec duration and virtually instantaneous risetime. Dependent variables were continuous (beat-to-beat) heart rate, stroke volume and blood pressure. The results suggest: (1) a vagal origen of the first acceleration and first deceleration and a sympathetic-parasympathetic interaction during the second acceleration and second deceleration of the heart rate response; (2) a blood pressure response pattern characterized by an increase during the first heart rate deceleration (4-11 sec), a posterior decrease coinciding with the second heart rate acceleration (from 12 to 37 sec), and a lighter increase during the second heart rate deceleration (from 38 to 63 sec); and (3) an implication of the baroreceptor reflex, including a baroreceptor mediated inhibition of the parasympathetic cardiac activity during the second accelerative component of the cardiac response.

Acoustic Stimulation↗
PubMed1995

Decelerative changes in heart rate during recognition of visual stimuli: effects of psychological stress.

The present study investigated whether the anticipatory heart rate (HR) deceleration response may reflect a pre-attentive process of stimulus registration and how reaction time (RT) and HR responses are influenced by the introduction of a psychological stressor. 60 subjects participated in a signalled RT task with a feedback stimulus containing information on their reaction time and accuracy. Changes in HR, skin conductance (SC) and respiration activity were monitored during performance in two conditions of a visual stimulus recognition task with a fixed foreperiod. In one condition subjects were informed that some electric shocks would be delivered to their right wrist (stress condition); in the other, subjects were simply engaged in the stimulus recognition without the stressor (no-stress condition). Stimuli consisted of geometrical figures and for each trial subjects were required to determine whether a probe stimulus was the same as or different from one of two memory items. Two reliable anticipatory HR decelerations, one preceding the imperative stimulus and the other preceding the feedback signal, were observed. Because the HR deceleration preceding the feedback signal (that did not require the inhibition of any specific motor response) was more pronounced than that obtained for the probe stimulus, it was concluded that HR deceleration response is an expression of stimulus processing rather than response preparation. Reaction times for 'same' stimuli were shorter than for 'different' stimuli. Averaged respiratory activity showed that with the onset of a warning signal subjects inspired and held their breath until they received the feedback signal. The averaged skin conductance data showed two main phasic increases, one after the probe stimulus onset and the other after the delivery of the feedback signal. This was taken to reflect the orienting response to the most significant stimuli.

Adult↗
PubMed1994

Prognostic value of Doppler transmitral flow patterns in patients with congestive heart failure.

OBJECTIVES: This study was designed to determine whether Doppler echocardiographic transmitral flow patterns can predict cardiac mortality in patients with congestive heart failure. BACKGROUND: Previous studies have indicated that Doppler transmitral flow patterns are related to New York Heart Association functional class and exercise capacity in patients with congestive heart failure. However, the prognostic significance of these flow patterns is not known. METHODS: We analyzed the relation of transmitral flow patterns and cardiac mortality in 100 consecutive patients (76 men, 24 women; mean [+/- SD] age 60 +/- 11 years) with congestive heart failure symptoms and left ventricular ejection fraction < 40%. At the time of entry into the study, functional class and ejection fraction by radionuclide angiography were determined, and Doppler echocardiography was performed in all patients. Transmitral flow was obtained from the apical four-chamber view at the mitral annulus level. Measurements included early (E) and atrial (A) filling velocities, E/A ratio and deceleration time of the E wave. The patients were assigned to two groups according to E/A ratio or deceleration time of transmitral flow patterns, or both: a non-restrictive group (42 patients) with E/A < or = 1 or E/A = 1 to 2 and deceleration time > 140 ms, and a restrictive group (58 patients) with E/A > or = 2 or E/A = 1 to 2 and deceleration time < or = 140 ms. RESULTS: Of 100 patients, 26 died during a mean follow-up period of 16 +/- 8 months. The cumulative cardiac mortality rate determined by the Kaplan-Meier method was 14% at 1 year and 35% at 2 years. Cox proportional hazards model analysis revealed that transmitral flow (restrictive vs. nonrestrictive, chi-square 6.99, p = 0.008), patient gender (female vs. male, chi-square 4.59, p = 0.03) and New York Heart Association functional class (IV vs. II, chi-square 3.95, p = 0.05) were significantly related to cardiac mortality in patients with congestive heart failure. Mortality rate in the restrictive group was markedly higher than that in the nonrestrictive group at 1 year (19% vs. 5%, respectively, p < 0.05) and at 2 years (51% vs. 5%, respectively, p < 0.01) by log-rank test. Relative risk for cardiac death was estimated as 4.1 at 1 year and 8.6 at 2 years in the restrictive group compared with the nonrestrictive group. CONCLUSIONS: In patients with congestive heart failure, a restrictive transmitral flow pattern, female gender and advanced functional class are predictive of higher cardiac mortality. The restrictive transmitral flow pattern by Doppler echocardiography is the single best clinical predictor for cardiac death in patients with congestive heart failure.

Aged↗
PubMed2000

Wisconsin Card Sorting in adolescents: analysis of performance, response times and heart rate.

Forty-nine adolescents performed the Wisconsin Card Sorting Test (WCST). A main PCA component of WCST performance was identified as 'efficiency of reasoning'. This factor was related to feedback processing. From the WCST, a perseveration score can be derived. Perseveration is the continued application of a rule, after it has been disconfirmed. We compared more and less perseverating subjects in relation to stimulus-response (SR) time, feedback inspection time and cardiac acceleration and deceleration. Less perseverating subjects responded faster, and had longer and more adaptive inspection times of error feedback. We examined the switch from rule application to rule search, and the difference between correct and error responses. A transient cardiac deceleration at the initiation of rule search was interpreted as a change in supervisory attention. An error-related deceleration to negative feedback was interpreted as a disturbance of higher control processing. Previous trial feedback influenced current processing time, feedback inspection time, and the cardiac acceleration and deceleration responses.

Adolescent↗
PubMed1998

Imaging of the distal left anterior descending coronary artery by transthoracic color-Doppler echocardiography.

Two-dimensional echocardiography evaluates the effect of myocardial ischemia on left ventricular wall motion, but a direct measure of coronary flow by this method is still lacking. The aim of the present study is to evaluate the efficacy of new, high-resolution ultrasound equipment designed to image by color Doppler transthoracic echocardiography the epicardial and intramural coronary vessels. We have studied 33 consecutive patients in apical projections, to detect by color Doppler > or = 1 segments of the middle-distal tract of the left anterior descending coronary artery. In 25 of 33 patients (76%), the middle-distal tract of the left anterior descending coronary artery was imaged by color Doppler. In 15 of 33 patients (46%), the periapical tract of the left anterior descending was imaged along with its perforating branches. In 2 of 4 patients who had coronary artery bypass grafting, the anastomosis between the left internal mammary artery and the left anterior descending coronary artery was imaged. Once the coronary artery was imaged, pulsed Doppler was used to measure coronary blood flow velocity at rest. Peak and mean flow velocity, as well as the deceleration time (msec) and deceleration rate (cm/sec2), were measured on the diastolic phase of the Doppler tracing. In all 25 patients, it was possible to measure by pulsed Doppler the coronary flow velocity pattern characterized by a typical prevalent diastolic component. Peak diastolic flow velocity was 50 +/- 17 cm/sec and mean diastolic flow velocity was 37 +/- 12 cm/sec. The deceleration time was 916.2 +/- 429.1 msec and the deceleration rate was 86.3 +/- 69.3 cm/sec2. The Doppler pattern of the grafted mammary artery was different from the native mammary flow. This new noninvasive imaging technique of the coronary arteries promises to expand the field of diagnostic and experimental echocardiography and brings new insight into the pathophysiology of ischemic heart disease.

Adult↗
PubMed1999

Estimation of pulmonary wedge pressure by transmitral Doppler in patients with chronic heart failure and atrial fibrillation.

Previous studies have demonstrated that left ventricular (LV) filling pressures can be estimated from transmitral Doppler recording in patients in sinus rhythm who have a broad spectrum of cardiac diseases. However, the correlation between pulmonary wedge pressure (PWP) and mitral Doppler profile has not yet been clearly defined in patients with atrial fibrillation, particularly in the presence of severe LV systolic dysfunction. The aim of this study was to evaluate the correlations between PWP and transmitral Doppler variables in patients with atrial fibrillation and chronic heart failure due to dilated cardiomyopathy. PWP and the mitral Doppler profile were simultaneously recorded in 35 consecutive heart failure patients (28 men, 7 women; mean age, 69 +/- 9 years) with severe LV dysfunction (mean ejection fraction 22% +/- 5%). Doppler measurements were averaged over 10 cardiac cycles. In addition, left atrial areas were derived from the apical 4-chamber view. Significant relations were observed between PWP and several parameters derived from the mitral flow: isovolumic relaxation time (r = -70), acceleration rate (r = 0.78), deceleration rate (r = 0.82), and deceleration time (r = -0.95). However, by stepwise multivariate analysis, deceleration time emerged as the sole independent predictor of PWP (r2 = 0.95, F = 590). The analysis led to the following equation: PWP = 51 - 0.26 (deceleration time). Our data suggest that mitral Doppler echocardiography is a useful tool for predicting PWP in heart failure patients with severe LV dysfunction even in the presence of atrial fibrillation.

Aged↗
PubMed1993

A comparison between visual and computer analysis of antepartum fetal heart rate tracings.

OBJECTIVE: This study was designed to determine the intraobserver and interobserver variability in the visual assessment of fetal heart rate tracings and to evaluate the accuracy of the visual detection of accelerations and decelerations when compared with computerized fetal heart rate analysis. STUDY DESIGN: One hundred antepartum fetal heart rate tracings, of good quality and of 30 minutes' duration, were visually assessed by five expert observers on three occasions during a 12-month period. There were a total of seven questions related to either judgment or accuracy of each recording. Visual detection of fetal heart rate acceleration, deceleration, and estimated baseline was compared with computerized analysis. Statistical significance was determined by kappa coefficient and contingency table chi 2 analysis. RESULTS: Analysis with kappa coefficient reflecting intraobserver and interobserver agreement of judgment-related questions indicated poor agreement between observers when assessing short-term fetal heart rate variability (kappa 0.18), when making a decision to stop or continue recording (kappa 0.39), and when judging whether there is concern regarding fetal heart rate tracing (kappa 0.26). When compared with computerized analysis, clinicians had a tendency to recognize tracings as normal. In particular, they failed to identify 35% of tracings with 0 or 1 acceleration and failed to detect 92% of fetal heart rate decelerations. Variable decelerations associated with fetal movements were the major source of disagreement between observers and the computer. Only the estimation of baseline fetal heart rate had a high level of accuracy. CONCLUSION: We concluded that the poor level of accuracy in several components of the nonstress test was responsible for the low interobserver agreement seen in simple judgment-related questions such as decision to continue or stop fetal heart rate recordings.

Computers↗
PubMed1987

Second-trimester fetal monitoring and preterm delivery in pregnancies with systemic lupus erythematosus and/or circulating anticoagulant.

Antepartum fetal monitoring was initiated at 19 to 26 weeks' gestation in 15 pregnancies: six (five with systemic lupus erythematosus, one with circulating anticoagulant) with a complicated antepartum course (group 1); three, all systemic lupus erythematosus, with a normal antepartum course (group 2); and six normal control pregnancies (group 3). Group 1 all exhibited nonperiodic fetal heart rate decelerations, without the classical appearance of early, late, or variable decelerations, and four of the six had fetal bradycardia. In three group 1 cases, there was no active intervention because of early gestational age, and fetal death occurred at 23, 27, and 27 weeks, respectively. The other three patients in group 1 received betamethasone and were delivered by cesarean section at 28 to 30 weeks. There were no cases of respiratory distress syndrome or neonatal death. Five of the six infants in group 1 were small for gestational age. The nonperiodic fetal heart rate decelerations were absent in both groups 2 and 3 who all had normal fetal outcomes at term. The abnormal finding of women with nonperiodic fetal heart rate decelerations at 20 to 28 weeks may detect the fetus at risk for intrauterine death in pregnancies complicated by systemic lupus erythematosus or circulating anticoagulant. Continued surveillance, steroid induction of lung maturity, and delivery should be considered in these cases.

Adult↗
PubMed1999

A new splenic artery Doppler velocimetric index for prediction of severe fetal anemia associated with Rh alloimmunization.

OBJECTIVE: We developed a new Doppler index for the noninvasive prediction of severe fetal anemia by means of Doppler velocimetry of the main splenic artery. STUDY DESIGN: Doppler velocimetry of the main splenic artery was performed in 85 healthy fetuses and in 22 nonhydropic study case patients (41 measurements) at risk for anemia from Rh sensitization. The deceleration angle between the line describing the average slope during the diastolic phase of the cycle and the vertical axis was measured and expressed in multiples of the median (MoM) for gestational age. Severe anemia was defined as a hemoglobin deficit (mean hemoglobin for gestational age minus measured hemoglobin) >/=5 g/dL. Anemia overall was defined as a hemoglobin deficit >/=2 g/dL. RESULTS: Mean gestational age at cordocentesis was 28.6 weeks. Severe anemia was noted on 7 occasions (12.6%) and anemia was noted on 21 (51.2%) occasions. There was a significant correlation between deceleration angle and hemoglobin deficit >/=2 g/dL (r = 0.5763, P <.0001) and also with hemoglobin deficit >/=5 g/dL (r = 0.6418, P <.0001). At deceleration angles <0. 90 MoM, a 90.5% sensitivity and a 30% false-positive rate were achieved for anemia detection. At a threshold deceleration angle of <0.60 MoM, the sensitivity for severe anemia was 100%, with an 8.8% false-positive rate. CONCLUSION: We report a new and sensitive Doppler velocimetric technique for predicting severe anemia. By means of splenic artery velocimetry, all cases of severe anemia could be identified before the development of hydrops, with a >91% reduction in the rate of cordocentesis.

Anemia↗
PubMed2001

Characteristics of fetal heart rate tracings prior to uterine rupture.

OBJECTIVE: To identify the fetal heart rate patterns that occurred in a 2-h period of time preceding uterine rupture. METHODS: The fetal monitor strips and the medical records of patients with a confirmed diagnosis of uterine rupture were reviewed. These patients delivered at the University of Michigan Hospital from January 1, 1985 to December 31, 1999 and were >or =28 weeks gestational age. Asymptomatic uterine scar dehiscences were excluded. The weeks of gestation, the number of cesarean sections, the surgical findings, and the maternal complications were obtained from the review of the maternal records. The fetal monitor strips for the 2 h preceding the uterine rupture were analyzed, and the fetal heart rate patterns were classified. RESULTS: During the study period, there were 11 patients identified with uterine rupture. Seven of the 11 (64%) had operative or post-operative complications. There were no maternal deaths. Review of the eight fetal heart rate tracings available revealed 7/8 (87.5%) with recurrent late decelerations and 4/8 (50%) with terminal bradycardia. All four of the patients with fetal bradycardia were preceded by recurrent late decelerations (100%). CONCLUSIONS: The most common fetal heart rate abnormalities that occurred prior to uterine rupture were recurrent late decelerations and bradycardia. The appearance of recurrent late decelerations may be an early sign of impending uterine rupture.

Bradycardia↗
PubMed2001

Contributions of the individual ankle plantar flexors to support, forward progression and swing initiation during walking.

Walking is a motor task requiring coordination of many muscles. Previous biomechanical studies, based primarily on analyses of the net ankle moment during stance, have concluded different functional roles for the plantar flexors. We hypothesize that some of the disparities in interpretation arise because of the effects of the uniarticular and biarticular muscles that comprise the plantar flexor group have not been separated. Furthermore, we believe that an accurate determination of muscle function requires quantification of the contributions of individual plantar flexor muscles to the energetics of individual body segments. In this study, we examined the individual contributions of the ankle plantar flexors (gastrocnemius (GAS); soleus (SOL)) to the body segment energetics using a musculoskeletal model and optimization framework to generate a forward dynamics simulation of normal walking at 1.5 m/s. At any instant in the gait cycle, the contribution of a muscle to support and forward progression was defined by its contribution to trunk vertical and horizontal acceleration, respectively, and its contribution to swing initiation by the mechanical energy it delivers to the leg in pre-swing (i.e., double-leg stance prior to toe-off). GAS and SOL were both found to provide trunk support during single-leg stance and pre-swing. In early single-leg stance, undergoing eccentric and isometric activity, they accelerate the trunk vertically but decelerate forward trunk progression. In mid single-leg stance, while isometric, GAS delivers energy to the leg while SOL decelerates it, and SOL delivers energy to the trunk while GAS decelerates it. In late single-leg stance through pre-swing, though GAS and SOL both undergo concentric activity and accelerate the trunk forward while decelerating the downward motion of the trunk (i.e., providing forward progression and support), they execute different energetic functions. The energy produced from SOL accelerates the trunk forward, whereas GAS delivers almost all its energy to accelerate the leg to initiate swing. Although GAS and SOL maintain or accelerate forward motion in mid single-leg stance through pre-swing, other muscles acting at the beginning of stance contribute comparably to forward progression. In summary, throughout single-leg stance both SOL and GAS provide vertical support, in mid single-leg stance SOL and GAS have opposite energetic effects on the leg and trunk to ensure support and forward progression of both the leg and trunk, and in pre-swing only GAS contributes to swing initiation.

Adult↗
PubMed2003

Postural stability of the human mandible during locomotion.

Movements of the head and of the mandible relative to the head were measured in human subjects walking and running on a treadmill at various speeds and inclinations. A miniature magnet and piezo-electric accelerometer assembly was mounted on the mandibular incisors, and a Hall-effect sensor along with a second accelerometer mounted on a maxillary incisor along a common vertical axis. Signals from these sensors provided continuous records of vertical head and mandible acceleration, and relative jaw position. Landing on the heel or on the toe in different forms of locomotion was followed by rapid deceleration of the downward movement of the head and slightly less rapid deceleration of the downward movement of the mandible, i.e., the mandible moved downwards relative to the maxilla, then upwards again to near its normal posture within 200 ms. No tooth contact occurred in any forms of gait at any inclination. The movement of the mandible relative to the maxilla depended on the nature and velocity of the locomotion and their effects on head deceleration. The least deceleration and hence mandibular displacement occurred during toe-landing, for example, during "uphill" running. The maximum displacement of the mandible relative to the head was less than 1mm, even at the fastest running speed. The mechanisms that limit the vertical movements of the jaw within such a narrow range are not known, but are likely to include passive soft-tissue visco-elasticity and stretch reflexes in the jaw-closing muscles.

Acceleration↗
PubMed2002

Characteristics of maternal heart rate patterns during labor and delivery.

OBJECTIVE: To find patterns characteristic of maternal heart rates recorded by an electronic fetal monitor and compare them with concomitant fetal heart rate (FHR) patterns. METHODS: Maternal heart rates and FHRs during active labor and delivery were simultaneously recorded in 26 parturients with singleton pregnancies in vertex presentation. The FHRs were obtained by an external ultrasound transducer or via a spiral scalp electrode and maternal heart rates by a triple-wire cable with electrocardiographic electrodes attached to the chest. Representative tracings of 30-60 minutes duration were selected from all stages of labor and after delivery of the placenta. Quantitative assessments were carried out under guidelines from the National Institute of Child Health and Human Development after blinding the source of these tracings. Patterns were compared by appropriate statistical analyses. RESULTS: Baseline maternal heart rates were significantly lower and their variability significantly higher than FHRs during all stages of labor. Maternal heart rates showed no decelerations; the proportion of tracings with accelerations increased as labor advanced, most of them coinciding with uterine contractions or bearing down efforts. The FHRs had both decelerations and accelerations. However, tracings with only accelerations (and no decelerations) were observed in decreasing frequency as labor advanced. Maternal accelerations had higher amplitudes and longer durations than fetal accelerations, especially in the second stage of labor. CONCLUSION: Maternal heart rate patterns recorded by electronic fetal monitors closely resemble fetal patterns. Baseline "fetal bradycardia," the absence of decelerations in the second stage of labor, and marked accelerations coinciding with uterine contractions may suggest a maternal heart rate rather than an FHR recording.

Adult↗
PubMed2002

Problems with intrapartum fetal heart rate monitoring interpretation and patient management.

Fetal heart rate (FHR) monitoring was introduced over 3 decades ago into clinical use and patient management. It continues to be the predominant method for intrapartum fetal surveillance despite questions about its efficacy and outcomes associated with its use. Currently, there appears to be a consensus regarding the reassuring value of a normal reactive pattern without decelerations. Patterns containing absent variability associated with persistent late decelerations, severe variable decelerations, and prolonged decelerations are generally believed to be ominous and may correlate with hypoxia of such severity that fetal central nervous system (CNS) damage may already have occurred. The clinician, however, is faced with FHR patterns between these extremes, and there appears to be a lack of consensus about their management. Furthermore, there is recent evidence that a fetal inflammatory response may lead to CNS damage, and the FHR patterns associated with this condition are not yet understood nor are there any intervention strategies that have been shown to benefit such fetuses. This article is an attempt to illustrate these situations and offer an approach useful to the clinician faced with such FHR patterns.

Electrocardiography↗
PubMed1997

Amniotic fluid distribution in predicting perinatal outcome in patients with ruptured membranes.

OBJECTIVE: To determine if amniotic fluid distribution predicts perinatal outcome in women with spontaneously ruptured membranes. METHODS: Patients presenting for labor and delivery with spontaneously ruptured membranes had amniotic fluid indices determined upon admission. Those with greater than 50% of their amniotic fluid in the upper quadrants were placed in the upper-greater group and those with greater than 50% in the lower quadrants were placed in the lower-greater group. The groups were compared with respect to meconium staining, 1- or 5-minute Apgar scores below 7, persistent variable or late decelerations, umbilical arterial or venous pH below 7.20, cesarean for non-reassuring fetal heart rate monitoring, and neonatal intensive care unit admissions. RESULTS: One hundred women were studied, 60 in the upper-greater group and 40 in the lower-greater group. Significant differences between upper-greater and lower-greater distributions were noted in meconium staining (28.3% compared with 0%, P < .001), 1-minute Apgar score below 7 (16.7% compared with 2.5%, P < .027), variable decelerations (63.3% compared with 25.0%, P < .001), late decelerations (23.3% compared with 0%, P < .001), and cesarean for non-reassuring fetal heart tracing (11.6% compared with 0%, P < .025). The negative predictive values for all of the variables studied were in the range 92.5-100%, with the exception of variable decelerations (75%). CONCLUSION: Amniotic fluid distribution predicts perinatal outcome in patients with ruptured membranes. This test's high negative predictive value indicates its potential as a valuable screening tool. These results may provide additional guidance in defining the intrapartum management of patients presenting with ruptured membranes.

Adult↗
PubMed2001

How individual age-associated changes may influence human morbidity and mortality patterns.

Patterns of human mortality share common traits in different populations. They include higher mortality in early childhood, lower mortality during the reproductive period, an accelerated increase of mortality near the end of the reproductive period, and deceleration in the mortality increase at oldest old ages. The deceleration of mortality rate is one of the most intriguing recent findings in longevity research. The role of differential selection in this phenomenon has been well studied. Possible contribution of individual aging in the shape of mortality curve is also recognized. However, this contribution has not been studied in details. In this paper, we specify most common patterns of age-associated changes in an individual organism and discuss their possible influence on morbidity and mortality in population. We subdivide individual age-associated changes into three components, having different influence on morbidity and mortality: (1) basal, (2) ontogenetic, and (3) time-dependent. Basal changes are connected with the universal decrease in the rate of living during an individual life. As a result, some phenotypic effects of aging may accumulate in an organism at a slower rate with age. Basal changes are likely to contribute to a plateau of morbidity often observed at old ages, and may partially be responsible for mortality deceleration at oldest old ages. Ontogenetic component is connected with change of the stages of ontogenesis (e.g., the growth, the reproductive period and the climacteric) during an individual life. The ontogenesis-related changes contribute to wave-like patterns of morbidity in population and may partially be responsible for mortality increase at middle ages and its deceleration at old ages. Time-dependent changes are connected with long-time exposure of an organism to different harmful factors. They are most likely to contribute to morbidity and mortality acceleration. We discuss how all three components of individual age-associated changes may interact in human organism and influence patterns of morbidity and mortality in population.

Aging↗