(1/19128) Graphic monitoring of labour.
The parturograph is a composite record designed for the monitoring of fetal and maternal well-being and the progress of labour. It permits the early recognition of abnormalities and pinpoints the patients who would benefit most from intervention. Observations are made from the time of admission of the mother to the caseroom and recorded graphically. Factors assessed include fetal heart rate, maternal vital signs and urine, cervical dilatation, descent of the presenting fetal part, and frequency, duration and intensity of uterine contractions. (+info)
(2/19128) Reduction in baroreflex cardiovascular responses due to venous infusion in the rabbit.
We studied reflex bradycardia and depression of mean arterial blood pressure (MAP) during left aortic nerve (LAN) stimulation before and after volume infusion in the anesthetized rabbit. Step increases in mean right atrial pressure (MRAP) to 10 mm Hg did not result in a significant change in heart rate or MAP. After volume loading, responses to LAN stimulation were not as great and the degree of attenuation was propoetional to the level of increased MRAP. A change in responsiveness was observed after elevation of MRAP by only 1 mm Hg, corresponding to less than a 10% increase in average calculated blood volume. after an increase in MRAP of 10 mm Hg, peak responses were attenuated by 44% (heart rate) and 52% (MAP), and the initial slopes (rate of change) were reduced by 46% (heart rate) and 66% (MAP). Comparison of the responses after infusion with blood and dextran solutions indicated that hemodilution was an unlikely explanation for the attenuation of the reflex responses. Total arterial baroreceptor denervation (ABD) abolished the volume-related attenuation was still present following bilateral aortic nerve section or vagotomy. It thus appears that the carotid sinus responds to changes inblood volume and influences the reflex cardiovascular responses to afferent stimulation of the LAN. On the other hand, cardiopulmonary receptors subserved by vagal afferents do not appear to be involved. (+info)
(3/19128) Quantification of baroreceptor influence on arterial pressure changes seen in primary angiotension-induced hypertension in dogs.
We studied the role of the sino-aortic baroreceptors in the gradual development of hypertension induced by prolonged administration of small amounts of angiotensin II (A II) in intact dogs and dogs with denervated sino-aortic baroreceptors. Short-term 1-hour infusions of A II(1.0-100 ng/kg per min) showed that conscious denervated dogs had twice the pressor sensitivity of intact dogs. Long-term infusions of A II at 5.0 ng/kg per min (2-3 weeks) with continuous 24-hour recordings of arterial pressure showed that intact dogs required 28 hours to reach the same level of pressure attained by denervated dogs during the 1st hour of infusion. At the 28th hour the pressure in both groups was 70% of the maximum value attained by the 7th day of infusion. Both intact and denervated dogs reached nearly the same plateau level of pressure, the magnitude being directly related both the the A II infusion rate and the daily sodium intake. Cardiac output in intact dogs initially decreased after the onset of A II infusion, but by the 5th day of infusion it was 38% above control, whereas blood volume was unchanged. Heart rate returned to normal after a reduction during the 1st day of infusion in intact dogs. Plasma renin activity could not be detected after 24 hours of A II infusion in either intact or denervated dogs. The data indicate that about 35% of the hypertensive effect of A II results from its acute pressor action, and an additional 35% of the gradual increase in arterial pressure is in large measure a result of baroreceptor resetting. We conclude that the final 30% increase in pressure seems to result from increased cardiac output, the cause of which may be decreased vascular compliance. since the blood volume remains unaltered. (+info)
(4/19128) Evaluation of the force-frequency relationship as a descriptor of the inotropic state of canine left ventricular myocardium.
The short-term force-frequency characteristics of canine left ventricular myocardium were examined in both isolated and intact preparations by briefly pertubing the frequency of contraction with early extrasystoles. The maximum rate of rise of isometric tension (Fmas) of the isolated trabeculae carneae was potentiated by the introduction of extrasystoles. The ratio of Fmas of potentiated to control beats (force-frequency ratio) was not altered significantly by a change in muscle length. However, exposure of the trabeculae to isoproterenol (10(-7)M) significantly changed the force-frequency ratio obtained in response to a constant frequency perturbation. Similar experiments were performed on chronically instrumented conscious dogs. Left ventricular minor axis diameter was measured with implanted pulse-transit ultrasonic dimension transducers, and intracavitary pressure was measured with a high fidelity micromanometer. Atrial pacing was performed so that the end-diastolic diameters of the beats preceding and following the extrasystole could be made identical. Large increases in the maximum rate of rise of pressure (Pmas) were seen in the contraction after the extrasystole. The ratio of Pmax of the potentiated beat to that of the control beat was not changed by a 9% increase in the end-diastolic diameter, produced by saline infusion. Conversely, isoproterenol significantly altered this relationship in the same manner as in the isolated muscle. Thus, either in vitro or in situ, left ventricular myocardium exhibits large functional changes in response to brief perturbations in rate. The isoproterenol and length data indicate that the force-frequency ratio reflects frequency-dependent changes in the inotropic state, independent of changes in length. (+info)
(5/19128) Site of myocardial infarction. A determinant of the cardiovascular changes induced in the cat by coronary occlusion.
The influence of site of acute myocardial infarction on heart rate, blood pressure, cardiac output, total peripheral resistance (TPR), cardiac rhythm, and mortality was determined in 58 anesthetized cats by occlusion of either the left anterior descending (LAD), left circumflex or right coronary artery. LAD occlusion resulted in immediate decrease in cardiac output, heart rate, and blood pressure, an increase in TPR, and cardiac rhythm changes including premature ventricular beats, ventricular tachycardia, and occasionally ventricular fibrillation. The decrease in cardiac output and increase in TPR persisted in the cats surviving a ventricular arrhythmia. In contrast, right coronary occlusion resulted in a considerably smaller decrease in cardiac output. TPR did not increase, atrioventricular condition disturbances were common, and sinus bradycardia and hypotension persisted in the cats recovering from an arrhythmia. Left circumflex ligation resulted in cardiovascular changes intermediate between those produced by occlusion of the LAD or the right coronary artery. Mortality was similar in each of the three groups. We studied the coronary artery anatomy in 12 cats. In 10, the blood supply to the sinus node was from the right coronary artery and in 2, from the left circumflex coronary artery. The atrioventricular node artery arose from the right in 9 cats, and from the left circumflex in 3. The right coronary artery was dominant in 9 cats and the left in 3. In conclusion, the site of experimental coronary occlusion in cats is a major determinant of the hemodynamic and cardiac rhythm changes occurring after acute myocardial infarction. The cardiovascular responses evoked by ligation are related in part to the anatomical distribution of the occluded artery. (+info)
(6/19128) Hierarchy of ventricular pacemakers.
To characterize the pattern of pacemaker dominance in the ventricular specialized conduction system (VSCS), escape ventricular pacemakers were localized and quantified in vivo and in virto, in normal hearts and in hearts 24 hours after myocardial infarction. Excape pacemaker foci were localized in vivo during vagally induced atrial arrest by means of electrograms recorded from the His bundle and proximal bundle branches and standard electrocardiographic limb leads. The VSCS was isolated using a modified Elizari preparation or preparations of each bundle branch. Peacemakers were located by extra- and intracellular recordings. Escape pacemaker foci in vivo were always in the proximal conduction system, usually the left bundle branch. The rate was 43+/-11 (mean+/-SD) beats/min. After beta-adrenergic blockade, the mean rate fell to 31+/-10 beats/min, but there were no shifts in pacemaker location. In the infarcted hearts, pacemakers were located in the peripheral left bundle branch. The mean rate was 146+/-20 beats/min. In isolated normal preparations, the dominant pacemakers usually were in the His bundle, firing at a mean rate of 43+/-10 beats/min. The rates of pacemakers diminished with distal progression. In infarcted hearts, the pacemakers invariably were in the infarct zone. The mean firing rates were not influenced by beta-adrenergic blockade. The results indicate that the dominant pacemakers are normally in the very proximal VSCS, but after myocardial infarction pacemaker dominance is shifted into the infarct. Distribution of pacemaker dominance is independent of sympathetic influence. (+info)
(7/19128) Perioperative growth hormone treatment and functional outcome after major abdominal surgery: a randomized, double-blind, controlled study.
OBJECTIVE: To evaluate short- and long-term effects of perioperative human growth hormone (hGH) treatment on physical performance and fatigue in younger patients undergoing a major abdominal operation in a normal postoperative regimen with oral nutrition. SUMMARY BACKGROUND DATA: Muscle wasting and functional impairment follow major abdominal surgery. METHODS: Twenty-four patients with ulcerative colitis undergoing ileoanal J-pouch surgery were randomized to hGH (12 IU/day) or placebo treatment from 2 days before to 7 days after surgery. Measurements were performed 2 days before and 10, 30, and 90 days after surgery. RESULTS: The total muscle strength of four limb muscle groups was reduced by 7.6% in the hGH group and by 17.1% in the placebo group at postoperative day 10 compared with baseline values. There was also a significant difference between treatment groups in total muscle strength at day 30, and at the 90-day follow-up total muscle strength was equal to baseline values in the hGH group, but still significantly 5.9% below in the placebo group. The work capacity decreased by approximately 20% at day 10 after surgery, with no significant difference between treatment groups. Both groups were equally fatigued at day 10 after surgery, but at day 30 and 90 the hGH patients were less fatigued than the placebo patients. During the treatment period, patients receiving hGH had reduced loss of limb lean tissue mass, and 3 months after surgery the hGH patients had regained more lean tissue mass than placebo patients. CONCLUSIONS: Perioperative hGH treatment of younger patients undergoing major abdominal surgery preserved limb lean tissue mass, increased postoperative muscular strength, and reduced long-term postoperative fatigue. (+info)
(8/19128) Heart rate and subsequent blood pressure in young adults: the CARDIA study.
The objective of the present study was to examine the hypothesis that baseline heart rate (HR) predicts subsequent blood pressure (BP) independently of baseline BP. In the multicenter longitudinal Coronary Artery Risk Development in Young Adults study of black and white men and women initially aged 18 to 30 years, we studied 4762 participants who were not current users of antihypertensive drugs and had no history of heart problems at the baseline examination (1985-1986). In each race-sex subgroup, we estimated the effect of baseline HR on BP 2, 5, 7, and 10 years later by use of repeated measures regression analysis, adjusting for baseline BP, age, education, body fatness, physical fitness, fasting insulin, parental hypertension, cigarette smoking, alcohol consumption, oral contraceptive use, and change of body mass index from baseline. The association between baseline HR and subsequent systolic BP (SBP) was explained by multivariable adjustment. However, HR was an independent predictor of subsequent diastolic BP (DBP) regardless of initial BP and other confounders in white men, white women, and black men (0.7 mm Hg increase per 10 bpm). We incorporated the part of the association that was already present at baseline by not adjusting for baseline DBP: the mean increase in subsequent DBP was 1.3 mm Hg per 10 bpm in white men, white women, and black men. A high HR may be considered a risk factor for subsequent high DBP in young persons. (+info)