Continuous Heart Rate Monitoring Research Articles

The evaluation of smaller plasterboards on productivity, work demands and workload in construction workers

Manual handling of plasterboards in order to construct interior building walls is a risk factor for musculoskeletal complaints. Unfortunately, mechanical lifting aids to reduce the physical workload are impractical for this task. Therefore, the effect of smaller plasterboards on productivity, work demands and workload was evaluated in an exploratory study among experienced construction workers ( n=4–8) at the worksite. The dimensions and weight of the conventional and smaller plasterboards (PB) were: PB120 (2440×1200×15 mm; 33 kg) and PB90 (2440×900×12.5 mm; 20 kg), respectively. Productivity was defined as meters of plasterboard mounted. Work demands were assessed by means of real time observations of tasks and activities. Workload was determined using continuous heart rate monitoring and subjective judgments of perceived workload. Productivity and total work time per working day did not differ between PB120 and PB90. Duration of mounting (29% increase) and anchoring (26% increase) were longer for PB90 than PB120. Duration of lifting, carrying and turning over plasterboards, and percentage of heart rate reserve showed no difference between PB120 and PB90. A majority of the workers preferred PB90. For the last two reasons and because PB90 weighs approximately 40% less than PB120, PB90 seems preferable. The workload in both conditions, however, was considered high.

The Treatment Should Not Be Worse Than the Disease

Dr. Beilin does not consider the use of phenylephrine infusions to be justified given the “minor” consequences of hypotension during spinal anesthesia for cesarean delivery. We disagree. One should not underestimate the importance of hypotension and its prevention. Dr. Beilin contends that serious adverse effects from hypotension are “almost nonexistent.” However, history warns us that major complications can indeed occur when hypotension is inadequately managed.1Dr. Beilin cited several articles2–4to support his contention, but careful reading of these reveals somewhat different messages. Macarthur2reported that “several reviews of maternal anesthetic deaths identified inadequately treated maternal hypotension as the major source of spinal anesthesia's morbidity and mortality.” Desalu and Kushimo3attributed low Apgar scores in some neonates in their study to relatively long durations of hypotension and stated that hypotension should be avoided in pregnant patients. Juhani and Hannele4emphasized the high incidence of minor complications and recommended that “hypotensive periods should be prevented.” Surprisingly, Dr. Beilin suggests that hypotension is not associated with neonatal acidosis or low Apgar scores. Datta et al. 5showed just such an association more than 20 yr ago. More recently, concern has been expressed that spinal anesthesia depresses fetal pH and base excess.6We believe the most important cause of this is hypotension and the way that it is treated.7Dr. Beilin trivializes the seriousness of nausea and vomiting. Nausea and vomiting can cause significant distress to the patient and can interfere with surgery.8We regard its prevention as an important clinical indicator of quality of care. Examination of closed claims has emphasized the prominence of “minor” injuries including emotional distress in obstetric anesthesia cases,9and thus, there may also be medicolegal implications. Pulmonary aspiration has occurred;9that's pretty dangerous.Dr. Beilin describes treatment of hypotension as “straightforward.” The large volume of research dedicated to this subject argues otherwise. There remain major controversies over the choice, dose, timing, and methods of administration of vasopressors and fluids. Dr. Beilin implies that it is sufficient to wait for hypotension to occur and then treat it with small boluses of ephedrine. It was the inadequacy of this very approach that several years ago stimulated us to direct research toward finding a better way.10We make no excuses for our aggressive approach to the prevention of hypotension. Our work indicates that this provides the best outcomes for mother and baby.11Although, as stated in our article, we do advocate some caution with phenylephrine infusions because of the potential for blood pressure to transiently increase above baseline, we disagree that use of direct intraarterial blood pressure monitoring is necessary when using this technique in healthy patients. From our experience11–15of many years of using infusions of α agonists in many hundreds of patients, we have found measurement of noninvasive blood pressure every minute until delivery together with continuous monitoring of heart rate to be quite sufficient and, contrary to Dr. Beilin's opinion, quite practical. We have not found small transient increases in blood pressure and relative slowing of maternal heart rate to be harmful. Arguably, this is a safer physiologic state than profound vasodilation with marked tachycardia, the likely alternative. Furthermore, in clinical practice, with continuous heart rate monitoring and the freedom to titrate the phenylephrine infusion without the strict constraints of a study protocol, hypertension is less of a problem.No treatment is perfect. But make not the mistake of underestimating the disease.*The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. warwick@cuhk.edu.hk

System for simultaneously monitoring heart and breathing rate in mice using a piezoelectric transducer

We propose a novel system for simultaneously monitoring the heart rate (HR) and breathing rate (BR) of anesthetized mice using a piezoelectric transducer (PZT) placed under the body. It is known that a PZT, which transforms mechanical vibrations into electrical signals, can detect heart sounds and breathing movements. However, no PZT system has been reported for simultaneous and continuous monitoring of HR and BR, possibly due to difficulties in eliminating noises and errors caused by the amplitude fluctuation of heart sounds and breathing movements. These difficulties were overcome by custom-designed analogue circuitry and a microprocessor program, resulting in detection of HR and BR with a high reliability compared to the values obtained from ECG and a conventional airflow sensor. We believe that this practical and easy-to-use system can be applied to a wide variety of basic and clinical research fields.

Carotid Sinus Hypersensitivity in Asymptomatic Older Persons

Carotid sinus hypersensitivity is the most commonly reported cause of falls and syncope in older persons. Recent guidelines recommend 5 to 10 seconds of carotid sinus massage in supine and upright positions with beat-to-beat monitoring. The aim of this study was to determine the prevalence of carotid sinus hypersensitivity in (1) an unselected community sample of older people and (2) a subsample with no history of syncope, dizziness, or falls using recently standardized diagnostic criteria. One thousand individuals older than 65 years were randomly sampled from a single general practice register; 272 participants underwent supine and upright carotid sinus massage with continuous heart rate and phasic blood pressure monitoring. Carotid sinus hypersensitivity was defined as asystole of 3 seconds or greater and/or a drop in systolic blood pressure of 50 mm Hg or greater. Carotid sinus hypersensitivity was present in 107 individuals (39%); 24% had asystole of 3 seconds or greater during carotid sinus massage; and 16% had symptoms (including syncope) with carotid sinus hypersensitivity. Age (odds ratio, 1.05; 95% confidence interval, 1.00-1.09) and male sex (odds ratio, 1.71; 95% confidence intervals, 1.04-2.82) were the only predictors of carotid sinus hypersensitivity. In 80 previously asymptomatic individuals, carotid sinus hypersensitivity was present in 28 (35%) and accompanied by symptoms in 10. The 95th percentile for carotid sinus massage response was 7.3 seconds' asystole and a 77-mm Hg drop in systolic blood pressure. Carotid sinus hypersensitivity is common in older persons, even those with no history of syncope, dizziness, or falls. The finding of a hypersensitive response should not necessarily preclude further investigation for other causes of syncope.

Physical Activity Patterns of Children After Neonatal Arterial Switch Operation

Physical inactivity is a major atherosclerosis risk factor. The exercise tolerance is usually excellent after neonatal arterial switch operation, but those patients in whom coronary anomalies remain the main late complication, risk developing atherosclerotic coronary disease owing to perceived physical activity restrictions. We investigated physical activity patterns of 52 unselected children 7 to 14 years after neonatal arterial switch operation for transposition of the great arteries by 24-hour continuous heart rate monitoring. The percentage of heart rate reserve was used to measure the amounts of activities. Comparisons were made with 35 children with repaired atrial or ventricular septal defect and with 127 age-matched healthy children. Children after arterial switch operation accumulated 167.3 +/- 70.6, 25.3 +/- 12.9, and 15.7 +/- 11.3 minutes a day (mean +/- SD) of light, moderate, and vigorous physical activities, respectively. At the same activity levels, children with repaired septal defect accumulated 165.2 +/- 82.2, 26.2 +/- 11.7, and 16.2 +/- 9.1 minutes a day, and their healthy peers 164.8 +/- 74.5, 31.8 +/- 13.9, and 21.9 +/- 11.3 minutes a day. Both cardiac groups were significantly less active than the control group when considering moderate (p = 0.026) and vigorous activities (p = 0.006). Only 19% and 27% of the children after arterial switch operation engaged, respectively, in more than 30 minutes a day of moderate activity and 20 minutes a day of vigorous activity. Children after arterial switch operation, just like other cardiac children, do not meet the guidelines for physical activity. We should encourage regular physical activity to offset adult sedentary behavior and to prevent atherosclerotic cardiovascular disease in those patients whose long-term function of the coronary arteries remains a matter of concern.

Patterns of physical activity determined by heart rate monitoring among diabetic children

Background: Children with type 1 diabetes should be encouraged to participate in physical activity because exercise can benefit insulin sensitivity and improve known risk factors for atherosclerosis. Methods: Physical activity...

Relationships between anthropometry, cardiorespiratory fitness indices and physical activity levels in different age and sex groups in rural Senegal (West Africa)

Background: A high level of activity is commonplace in traditional subsistence societies. Physiological characteristics of individuals, including body composition and physical fitness, could be limiting factors when performing daily tasks.Objectives: The study investigated the relationships between cardiorespiratory fitness, nutritional status and physical activity patterns, so as to test the hypothesis that these relationships are less straightforward in children than in adults.Study design: Four different groups of individuals from rural Senegal were investigated: 99 10–13-year-old children of both sexes (11.1 ± 1.5 years old) from two settings in Senegal (Lambaye and Podor), 43 adolescent girls (15.5 ± 0.5 years), and 30 adult women (17–40 years).Methods: Subjects undertook a step test, and anthropometric measurements were collected. Continuous heart rate (HR) monitoring was performed for 8–12 h. The flex-HR method was used to estimate levels of activity (per cent of time spent under or over the flex-HR).Results: Ten to 13-year-old children and adolescent girls presented slight degrees of malnutrition. Adult women were apparently not nutritionally deprived. Differences in cardiorespiratory fitness were found among 10–13-year-old children, while adult women performed better than adolescent girls. Children from Lambaye had a higher level of activity than children from Podor. Similarly, adult women were more active than adolescent girls. No relationships were found between cardiorespiratory or anthropometric measurements and per cent of time spent above the flex-HR (>flex-HR) in 10–13-year-old children. In contrast, in adult women and adolescent girls, body composition and cardiorespiratory indices were significant predictors of activity levels.Conclusion: Our data support the hypothesis that activity levels are less dependent upon physiological characteristics in children than in adults in traditional subsistence societies.

What is the minimum duration of head-up tilt necessary to detect orthostatic hypotension?

There is uncertainty as to the minimum duration of head-up tilt (HUT) needed to detect orthostatic hypotension (OH). The orthostatic duration has variably been recommended to be 1, 2, 3, and 5 minutes. The purpose of the current study was 1) to determine the minimum duration of HUT necessary to detect OH and 2) to identify different patterns of orthostatic blood pressure (BP) response in patients with OH. We evaluated the medical records of 66 consecutive patients (mean age 70.0+/-10.1 years; 64% male) seen at Mayo Clinic-Rochester from 2000-2001 who fulfilled the criteria for OH (systolic blood pressure [SBP] reduction > or = 20 mmHg within 3 minutes of HUT) during routine clinical autonomic studies. All patients completed an autonomic reflex screen with continuous monitoring of heart rate and BP during supine rest and 5 minutes of 70 degree HUT. Severity of autonomic deficits was quantified with the Composite Autonomic Severity Score (CASS). Overall, BP was the lowest at 1 minute with gradual and partial recovery over the following 4 minutes. Eighty-eight percent of patients (N=58) developed OH by 1 minute of HUT, with an additional 11% (N=7) developing OH by 2 minutes and the remaining 1% (N=1) developing OH by 3 minutes. We identified two broad patterns of SBP response to HUT. Forty-eight percent (N=32) of patients demonstrated an initial drop in SBP (> or = 20 mm Hg),which remained stable until tilt-back. Thirty-six percent (N=24) demonstrated an initial drop (> or = 20 mmHg) followed by a progressive decline in SBP until tilt-back. Repeated measures analysis of variance confirmed that the SBP change in response to HUT differed significantly among patients with a stable vs. progressive pattern [F(3,32)=25.1, p<0.001). Patients with the progressive pattern also had more severe adrenergic impairment on the CASS (p=0.03) and were more likely to have their tilt test terminated early (prior to 5 minutes) due to presyncope (p<0.0001) than patients with the stable pattern. One minute of HUT will detect OH in the great majority (88%) of patients and three minutes will detect the balance. Orthostatic stress beyond 2 minutes is necessary to detect the pattern of progressive OH. Since this group has more severe adrenergic deficits than the group with stable OH, we suggest that the progressive pattern is due to greater impairment of compensatory reflexes. Recognition of the group with progressive fall in BP is important since this group may be at greater risk of orthostatic syncope.

Intrapartum Repetitive Maternal Heart Rate Deceleration Pattern Simulating Nonreassuring Fetal Status

Uterine contraction-associated accelerations of the maternal heart rate are considered to reflect both a transient contraction-related increase in cardiac output and endogenous catecholamine secretion. Uterine contraction-associated decelerations of the maternal heart rate are rare and remain unexplained. A young multiparous patient with systemic lupus erythematosus (postrenal transplant for lupus nephropathy-related renal failure) presented in early labor at 39 weeks gestation, prior to elective repeat cesarean section. Intrapartum continuous maternal heart rate monitoring demonstrated repetitive uterine contraction associated decelerations of the maternal heart rate of 60 beats per minute, each lasting 2 minutes, simulating nonreassuring fetal status. Simultaneously depicted fetal heart rate was reassuring. This case demonstrates an unusual marked early intrapartum affect of uterine contractions upon the maternal heart rate. In addition, this case illustrates the potentially dangerous similarity of an intrapartum maternal heart rate to an abnormal fetal heart rate pattern, and emphasizes the importance of correct identification of the maternal and fetal heart rates, respectively.

The effect of different intensity modalities of resistance training on beat-to-beat blood pressure in cardiac patients

Resistance training has been introduced in cardiac rehabilitation to give more benefit than traditional training. Haemodynamic evaluation of cardiac patients to resistance training has generally consisted of continuous HR monitoring and discontinuous blood pressure measurements. Blood pressure (BP) and heart rate (HR) responses to resistance training were evaluated using continuous monitoring (Finapres) during low (four sets of 17 repetitions at 40% of the one-repetition maximum strength [1-RM]) and high intensity resistance training (four sets of 10 repetitions at 70% of 1-RM) on a leg extension machine in 14 patients who participated in a rehabilitation programme. Work volume was identical in the low- and high-level resistance training. The HR and systolic blood pressure (SBP) during low intensity resistance training were always larger than during high intensity (P<0.001). Peak SBP increased from set 1 to set 3 and 4 during both low and high intensity resistance training (P<0.05). Peak HR was larger in set 4 (95+/-11 bpm) than in set 1 only during low intensity resistance training (91+/-12 bpm) (P<0.05). One-minute recovery periods did not allow a return to baseline HR and SBP during both low and high intensity modalities. The SBP and HR responses to resistance training are related to the duration of exercise. Sets with < or =10 repetitions of high intensity should be preferred to longer sets with low intensity. Pauses between exercise sets should exceed 1 min. Blood pressure should be measured during the last repetitions of the exercise set.

The Effect of Different Intensity Modalities of Resistance Training on Beat-to-Beat Blood Pressure in Cardiac Patients

BackgroundResistance training has been introduced in cardiac rehabilitation to give more benefit than traditional training. Haemodynamic evaluation of cardiac patients to resistance training has generally consisted of continuous HR monitoring and discontinuous blood pressure measurements.Design and MethodsBlood pressure (BP) and heart rate (HR) responses to resistance training were evaluated using continuous monitoring (Finapres) during low (four sets of 17 repetitions at 40% of the one-repetition maximum strength [1-RM]) and high intensity resistance training (four sets of 10 repetitions at 70% of 1-RM) on a leg extension machine in 14 patients who participated in a rehabilitation programme. Work volume was identical in the low- and high-level resistance training.ResultsThe HR and systolic blood pressure (SBP) during low intensity resistance training were always larger than during high intensity (P&lt;0.001). Peak SBP increased from set 1 to set 3 and 4 during both low and high intensity resistance training (P&lt;0.05). Peak HR was larger in set 4 (95 ± 11 bpm) than in set 1 only during low intensity resistance training (91 ± 12 bpm) (P&lt;0.05). One-minute recovery periods did not allow a return to baseline HR and SBP during both low and high intensity modalities.ConclusionsThe SBP and HR responses to resistance training are related to the duration of exercise. Sets with ≥ 10 repetitions of high intensity should be preferred to longer sets with low intensity. Pauses between exercise sets should exceed 1 min. Blood pressure should be measured during the last repetitions of the exercise set. Eur J Cardiovasc Prev Rehabil 12:12-17 © 2005 The European Society of Cardiology

Influence of Hepatic Impairment on??the Pharmacokinetics and Pharmacodynamics of Landiolol??Hydrochloride, an Ultra-Short-Acting ??1-Blocker

To investigate the effects of mild to moderate hepatic impairment on the pharmacokinetics and pharmacodynamics of landiolol hydrochloride, a new ultra-short-acting beta1-adrenergic antagonist. Six patients with hepatic impairment and six healthy volunteers were enrolled in the open-label, parallel-group study. Landiolol hydrochloride was given intravenously with a 1-minute loading infusion of 0.06 mg/kg/min, followed by a 60-minute infusion of 0.02 mg/kg/min using an automated infusion pump. Venous blood was drawn just before (predose) and 1, 2, 5, 15, 30 and 61 minutes after beginning the continuous intravenous infusion (during infusion); 2, 5, 10 and 30 minutes and 1, 4 and 8 hours after the end of the infusion (after infusion); and 24 hours after beginning the infusion (next day). Urine samples were collected up to 24 hours after beginning the infusion. Before subjects were discharged, an indocyanine green elimination test, clinical laboratory testing, physical examination and recording of ECGs and vital signs were performed. The geometric mean maximum plasma concentration and area under the concentration-time curve values for the patients with hepatic impairment were 42% and 44% higher, respectively, than those observed for the healthy volunteers, indicating that hepatic impairment affected the disposition of landiolol hydrochloride. There were no significant changes in the elimination half-life of the drug. There were no clinically significant differences between the two groups in terms of reductions in heart rate or blood pressure. The pharmacokinetic and pharmacodynamic characteristics of this ultra-short-acting beta1-blocker were maintained even in the patients with hepatic impairment. Although we did not observe any drug-related adverse events in these patients, hypotension or bradycardia should be considered, necessitating continuous monitoring of both heart rate and BP in patients with hepatic impairment who receive landiolol hydrochloride.

Anesthetic agents and the immature brain: are these toxic or therapeutic?

Anesthetic agents and the immature brain: are these toxic or therapeutic?

Circadian and Short-Term Regulation of Blood Pressure and Heart Rate in Transgenic Mice with Cardiac Overexpression of The β1-Adrenoceptor

Congestive heart failure is associated with a loss of circadian and short-term variability in blood pressure and heart rate. In order to assess the contribution of elevated cardiac sympathetic activity to the disturbed cardiovascular regulation, we monitored blood pressure and heart rate in mice with cardiac overexpression of the β1-adrenoceptor prior to the development of overt heart failure. Telemetry transmitters for continuous monitoring of blood pressure and heart rate were implanted in 8 to 9-week-old wildtype and transgenic mice, derived from crosses of heterozygous transgenic (line β1TG4) and wildtype mice. Cardiovascular circadian patterns were analyzed under baseline conditions and during treatment with propranolol (500 mg/L in drinking water). Short-term variability was assessed by spectral analysis of beat-to-beat data sampled for 30 min at four circadian times. Transgenic β1TG4 mice showed an increase in 24 h heart rate, while blood pressure was not different from wildtype controls. Circadian patterns in blood pressure and heart were preserved in β1TG4 mice. Addition of propranolol to the animals’ drinking water led to a reduction in heart rate and its 24 h variation in both strains of mice. Short-term variability in blood pressure was not different between wildtype and β1TG4 mice, but heart rate variability in the transgenic animals showed a rightward shift of the high-frequency component in the nocturnal activity period, suggesting an increase in respiratory frequency. In conclusion, the present study shows that both the circadian and the short-term regulation of blood pressure and heart rate are largely preserved in young, nonfailing β1-transgenic mice. This finding suggests that the loss of blood pressure and heart rate variability observed in human congestive heart failure cannot be attributed solely to sympathetic overactivity but reflects the loss of adrenergic responsiveness to changes in the activity of the autonomic nervous system.

Intermittent fasting and dietary supplementation with 2-deoxy-D-glucose improve functional and metabolic cardiovascular risk factors in rats.

Hypertension and insulin resistance syndrome are risk factors for cardiovascular disease, and it is therefore important to identify interventions that can reduce blood pressure and improve glucose metabolism. We performed experiments aimed at determining whether intermittent fasting (IF) can improve cardiovascular health and also tested the hypothesis that beneficial effects of IF can be mimicked by dietary supplementation with 2-deoxy-D-glucose (2DG) a non-metabolizable glucose analog. Four-month-old male rats were implanted with telemetry probes to allow continuous monitoring of heart rate, blood pressure, physical activity, and body temperature. Rats were then maintained for 6 months on one of three different dietary regimens: ad libitum feeding, IF, or 2DG supplementation. Rats on the IF regimen consumed 30% less food over time and had reduced body weights compared with rats fed ad libitum, whereas rats on the 2DG regimen did not reduce their food intake and maintained their body weight. Heart rate and blood pressure were significantly decreased within 1 month in rats on IF and 2DG diets and were maintained at reduced levels thereafter. Body temperature was significantly decreased in group IF, but not in group 2DG. Levels of serum glucose and insulin were significantly decreased in rats maintained on IF and 2DG-supplemented diets, suggesting that IF and 2DG diets affect insulin sensitivity in a similar manner. Finally, rats in groups IF and 2DG exhibited increased levels of plasma adrenocorticotropin and corticosterone, indicating that these diets induced a stress response. We conclude that reductions in blood pressure, heart rate, and insulin levels, similar to or greater than those obtained with regular physical exercise programs, can be achieved by IF and by dietary supplementation with 2DG by a mechanism involving stress responses.

Emergency pharmacological management of aggression among agitated psychotic patients in Japan.

Another study in the same intensive care unit showed that of 259 male patients with acute schizophrenia, 7 percent were dehydrated, a third had hypokalemia and leukocytosis, and twothirds of these patients showed elevated serum muscle enzymes (4). A quarter of the patients required medical management.

Ambulatory electrocardiographic monitoring: use of the implantable loop recorder in the evaluation of syncope.

Syncope may be related to a large spectrum of medical and psychologic disorders, yet the precise etiology is often difficult to determine. Although the evaluation of syncope involves extensive testing, nearly 50% of these individuals remain without definitive diagnosis. Because of the infrequent and unpredictable nature of syncope, many ambulatory screening techniques are not suited to diagnose syncope. The use of an implantable loop recording device provides continuous monitoring of heart rate and rhythm during syncopal events and may help clinicians arrive at a more precise diagnosis in a more timely manner. The Reveal Plus implantable loop recorder (ILR) (Medtronic USA, Minneapolis, Minn) has demonstrated its clinical utility in evaluating syncope and drug-refractory seizure disorders.

Geburtsasphyxie - ein immer noch ungelöstes Problem der Perinatalmedizin1

Birth asphyxia is defined as a severe disturbance of oxygen supply to the fetus, which develops during the first or second stage of labor. The diagnosis is confirmed by a severe metabolic acidosis in the umbilical cord blood, a persistent low Apgar as well as functional disturbances as a result of hypoxic damage in various organs including the central nervous system. Apart from morbidity and mortality in the neonatal phase long term effects are of considerable significance. Only 10 - 15 % of all cerebral palsy cases developing after delivery at term are a consequence of a hypoxic encephalopathy developing during the process of labor and delivery. For a long time it was ignored, that a number of pregnancy pathologies may lead to brain damage, which could also produce the typical symptoms of cerebral palsy. An abrupt disturbance of oxygen supply may be a result of cord compression, a premature separation of the placenta or of rupture of the uterus. These situations are in general easily recognized by typical clinical symptoms together with a sudden drop in fetal heart rate with a persistent bradycardia. In these cases it is only possible to prevent hypoxic brain damage, if the fetus can be delivered by emergency caesarian section within 15 - 20 minutes after the acute event. Diagnosis and evaluation of subacute or chronic forms of insufficient supply of oxygen of the fetus in labor is considerably more difficult. Reliability of continuous heart rate monitoring of the fetus during labor as well as validity of certain heart rate changes for the detection of developing hypoxia is a matter of ongoing dispute. In the presence of clearly pathological heart rate patterns hypoxic damage may already have occurred. Suspicious or "non-reassuring" heart rate alterations are frequent and only in a small percentage a real threat to the fetus in form of severe hypoxia will develop. Up until now there is no clear scientific proof that a combination of continuous fetal heart rate monitoring with additional tests can prevent hypoxic damage to the fetus. Future efforts should be directed towards improving reliability of the description of fetal heart rate patterns, the validity of the information provided by heart rate changes as well as the proof of the benefit of continuous monitoring of the fetus during labor and delivery as a means of preventing severe hypoxia and its consequences to fetal health.

Effect of adenosine on cerebral blood flow velocity.

Evidence suggests that adenosine (ADN) is a potent vasodilator of cerebral vessels. However, the feasibility of manipulating human cerebral vascular resistance with ADN has not been assessed by means of TCD. The purpose of this study was to quantitatively estimate the change in middle cerebral artery cerebral blood flow velocity (CBFV) in response to intravenous ADN infusion in humans. Eleven patients with subacute cerebrovascular events (ischemic stroke, transient ischemic attack, or hemorrhage) undergoing adenosine-thallium stress testing were studied before, during, and after ADN infusion to evaluate the effect of ADN on cerebral blood flow velocity. Continuous blood pressure (BP), heart rate (HR), respiration rate (RR), end-tidal CO2 (ET-CO2), and transcranial Doppler ultrasonography monitoring of CBFV and pulsatility index (PI) in both middle cerebral arteries were performed. The mean CBFVs were 65.4 +/- 19.2 cm/s before, 55.4 +/- 18.1 cm/s during, and 64.1 +/- 22.5 cm/s after ADN infusion, which represents a statistically significant decrease during ADN test compared with both baseline (P = .007) and posttest levels (P = .017). The PI was increased during the test (0.91 +/- 0.2) when compared with baseline (0.71 +/- 0.1) (P = .007). During ADN injection, mean HR increased (P = .004) and mean ET-CO2 levels decreased significantly (P = .003). Mean BP and RR did not change significantly. The authors hypothesize that any direct vasodilatory effect of ADN on the distal cerebral peripheral vasculature may be negated by an effect of ADN on depth of respiration resulting in hypocapnia and secondary distal vasoconstriction.

Randomised controlled trial of cardiotocography versus Doppler auscultation of fetal heart at admission in labour in low risk obstetric population.

Objective: To compare the effect of admission cardiotocography and Doppler auscultation of the fetal heart on neonatal outcome and levels of obstetric intervention in a low risk obstetric population.Design: Randomised...