Assessment of beat to beat changes in cardiac output during the Valsalva manoeuvre using electrical bioimpedance cardiography

1987 ◽  
Vol 72 (4) ◽  
pp. 423-428 ◽  
Author(s):  
Stephen A. Smith ◽  
Mahmood M. Salih ◽  
William A. Littler
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Normal Subjects ◽  
Valsalva Manoeuvre ◽  
Impedance Measurements ◽  
Electrical Bioimpedance ◽  
Valsalva's Manoeuvre ◽  
The Mean ◽  
Bioimpedance Cardiography ◽  
Cardiac Stroke Volume

1. Beat to beat changes in cardiac output during standardized Valsalva's manoeuvres were recorded using electrical bioimpedance cardiography in 13 normal subjects. 2. Cardiac output increased by 12 ± 5% after 1 s of straining solely because of an increase in heart rate. Subsequently, cardiac stroke volume and cardiac output fell during the strain to lows of − 40 ± 6% and − 21 ± 3% respectively at 15 s. 3. There was a sustained increased in cardiac output (maximum + 17 ± 4%) in the late post strain period. 4. The mean coefficient of variation in impedance measurements of cardiac output was 6.8% during all parts of Valsalva's manoeuvre, with no single value exceeding 10%.

Effets du statut socioéconomique sur l'activité physique d'enfants prépubères

2003 ◽  
Vol 28 (2) ◽  
pp. 190-203 ◽  
Author(s):  
Alexandre Melin ◽  
Philippe Obert ◽  
Pierre Bonnet ◽  
Daniel Courteix
Keyword(s):  
Physical Activity ◽  
Heart Rate ◽  
Socioeconomic Status ◽  
Normal Subjects ◽  
Habitual Physical Activity ◽  
Heart Rate Reserve ◽  
Statut Socioéconomique ◽  
The Mean ◽  
And Gender ◽  
Daily Time

In order to assess possible influences of socioeconomic status and gender on habitual physical activity (HPA) of prepubertal French children, daily heart rate was 24-hr-monitored in 65 normal subjects for 2 days in the same school week. HPA was evaluated as the mean daily time spent at heart rates greater than 140 bpm (tFC > 140), 160 bpm (tFC > 160), 50% (tFC > 50%), and 70% (tFC > 70%) of the heart rate reserve. An effect of socioeconomic status (determined by questionnaire) was found in boys, with HPA being greater in the underprivileged ones (tFC > 140: 51.8 ± 30.1 vs 33.0 ± 14.1 min, p < .05; tFC > 160: 22.7 ± 16.6 vs 11.1 ± 7.4 min, p < .05; tFC > 50%: 61.4 ± 33.5 vs 46.5 ± 17.1 min, p < .06; tFC > 70%: 20.1 ± 15.2 vs 10.6 ± 7.1, p < .05). Boys were more active than girls, but only in the underprivileged group (tFC > 140: 51.8 ± 30.1 vs 32.8 ± 26.0 min, tFC > 160: 22.7 ± 16.6 vs 9.9 ± 8.2 min, p < .05; tFC > 50%: 61.4 ± 33.5 vs 37.4 ± 23.8 min, p < .05; tFC > 70%: 20.1 ± 15.2 vs 8.1 ± 6.3, p < .05). Cultural factors could be involved in these results. Key words: habitual physical activity, heart rate, heart rate meter, gender, energy expenditure

Base-line effects on response of stroke volume to leg exercise in the supine position

1964 ◽  
Vol 19 (4) ◽  
pp. 639-643 ◽  
Author(s):  
M. H. Frick ◽  
Timo Somer
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Normal Subjects ◽  
Significant Rise ◽  
Base Line ◽  
Horizontal Position ◽  
Volume Data ◽  
Leg Exercise ◽  
Low Levels

Cardiac output was measured with dye dilution in normal subjects at rest in horizontal position, at rest supine with the legs on the pedals, and during increasing work loads. Experiments were designed to clarify the effect of leg raising on comparisons of stroke volume at various levels of exercise. Leg raising evoked a 19% increase in stroke volume and a decrease in heart rate. Oxygen uptake and A-V O2 difference remained unaltered. In comparing stroke volume at mild exercise with leg-raised resting position, no change occurred contrasting the significant rise when compared with horizontal position. At mild exercise cardiac output response was relatively flat, whereas A-V O2 difference rose sharply. At heavier exercise cardiac output rose more steeply and approximately linear to oxygen consumed. Stroke volumes at these loads were significantly higher than levels in both of the resting positions. Ignorance of the effect of leg raising results in misinterpretation of the stroke volume data at low levels of supine exercise when greatly enhanced tissue extraction of oxygen allows smaller blood flow increments. base line in exercise; exercise stroke volume; stroke volume, exercise; stroke volume, base line; supine exercise Submitted on December 13, 1963

The Autonomic Nervous Tone Abnormalities in the Genesis of the Impaired Baroreflex Responsiveness in Borderline Hypertensive Subjects

1982 ◽  
Vol 62 (6) ◽  
pp. 581-588 ◽  
Author(s):  
Massimo Volpe ◽  
Bruno Trimarcoy ◽  
Bruno Ricciardelli ◽  
Carlo Vigorito ◽  
Nicola De Luca ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Arterial Pressure ◽  
Normal Subjects ◽  
Tissue Pressure ◽  
Combined Administration ◽  
Propranolol Treatment ◽  
The Mean ◽  
Pressure Changes ◽  
Neck Chamber

1. The effects of intravenous administration of neostigmine and propranolol, individually or in combination, on baroreflex responsiveness have been evaluated in 18 borderline hypertensive subjects and in 14 age-matched control subjects. 2. Baroreceptor sensitivity was tested by evaluating both heart rate response to phenylephrine-induced increase in arterial pressure, and heart rate and blood pressure changes induced by increasing neck-tissue pressure by means of a neck-chamber. 3. In borderline hypertensive subjects a reduced baroreflex responsiveness was demonstrated with both stimuli as compared with normal subjects. Neostigmine administration improved consistently both reflex responses. Similarly, after propranolol treatment, borderline hypertensive subjects showed a significant enhancement of the baroreflex sensitivity. Finally, the combined administration of neostigmine and propranolol restored the baroreflex responses. In fact, both the mean slopes of the regression lines between blood pressure and R-R interval after phenylephrine and the increase in mean arterial pressure and heart rate induced by the reduction in carotid transmural pressure in borderline hypertensive subjects were similar to those observed in normals. 4. These findings indicate that in borderline hypertensive subjects the impairment of baroreflex responsiveness is mainly due to abnormalities of autonomic regulation.

scholarly journals COMPARATIVE CHARACTERISTICS OF THE DYNAMICS OF CARDIOVASCULAR AND RESPIRATORY EFFECTS OF PNEUMOPERITONEUM BASED ON CARBON DIOXIDE AND ARGON IN LAPAROSCOPIC CHOLECYSTECTOMY

2021 ◽  
pp. 90-95
Author(s):  
O. L. Tkachuk ◽  
R. L. Parakhoniak ◽  
S. V. Melnyk ◽  
O. O. Tkachuk-Hryhorchuk
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Cardiac Output ◽  
Laparoscopic Cholecystectomy ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Negative Impact ◽  
Abdominal Pressure ◽  
The Mean ◽  
Respiratory Systems

Pneumoperitoneum is one of the most critical components of laparoscopic surgery, which has a negative effect on gas exchange and stress to circulatory buffering system. One of the top priorities of laparoscopic technologies is to minimize the impact on the respiratory and cardiovascular systems, metabolic dynamics and compensatory abilities of homeostasis. The main goal of this research work is to compare the effects of carboxyperitoneum and argonoperitoneum on the intraoperative dynamics of CO2 concentration as well as cardiovascular and respiratory characteristics in patients undergoing laparoscopic cholecystectomy for various forms of cholelithiasis. Materials and methods. Four experimental groups involved patients based on their nosological form of cholelithiasis and the gas used to induce pneumoperitoneum. All patients underwent laparoscopic cholecystectomy by means of standard procedure. Either medical carbon dioxide or medical argon was used to induce pneumoperitoneum. Intraoperative monitoring of blood carbon dioxide levels PaCO2 was performed by taking venous blood every 15 minutes. Capnometry was performed by means of mainstream analysis using “BIOMED” BM1000C modular patient monitor by recording the discrete values of PetCO2 every 15 minutes, as well as by analyzing photocopies of capnography curves every 15 minutes. Intraoperative echocardiography was performed to identify the mean arterial pressure (MAP), heart rate (HR) and cardiac output (CO) in order to assess the effects of different types of pneumoperitoneum on the cardiovascular system. Results. The obtained data confirm the expected difference in the indices of cardiorespiratory functions between patients with acute cholecystitis and cholelithiasis without signs of inflammation. The investigation revealed that under the influence of pneumoperitoneum, heart rate and mean arterial pressure increase, while the cardiac output decreases. The respiratory pressure marker depends more on the intra-abdominal pressure and presumably the patient’s body type than on the presence of inflammatory syndrome. Argon insufflation has a slight negative impact on the cardiovascular system. Particularly, the mean arterial pressure and heart rate increase, while the cardiac output marker is less decreased as compared to the use of carbon dioxide. Abdominal pressure has a significant effect on the cardiovascular and respiratory systems regardless of the used type of gas. The combination of high intra-abdominal pressure with the elevated head end of the operating table, which is a common practise during cholecystectomy, has especially great influence on cardiovascular and respiratory functions. Operation which is carried out at decreased pressure allows reducing the deviations of practically all indices. Conclusions. Thus, the cardiovascular and respiratory systems adapt under the influence of pneumoperitoneum, providing compensation for the negative effects of mechanical and resorptive-metabolic character. Compensatory-adaptive abilities of the cardiovascular and respiratory systems increase with the decrease of intra-abdominal pressure. The use of argon as a working gas for insufflation into the abdominal cavity during laparoscopy reduces the negative impact of pneumoperitoneum on the cardiovascular and respiratory systems, providing a greater reserve of homeostatic and buffer systems of the body.

scholarly journals Norepinephrine versus phenylephrine infusion for preventing postspinal hypotension during cesarean section for twin pregnancy: a double-blinded randomized controlled clinical trial

2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Zijun Chen ◽  
Jieshu Zhou ◽  
Li Wan ◽  
Han Huang
Keyword(s):  
Blood Pressure ◽  
Clinical Trial ◽  
Heart Rate ◽  
Cardiac Output ◽  
Cesarean Section ◽  
Area Under The Curve ◽  
Neonatal Outcomes ◽  
The Mean ◽  
Phenylephrine Infusion ◽  
Double Blinded

Abstract Background Compared with singleton pregnancy, twin gestation is featured by a greater increase in cardiac output. Therefore, norepinephrine might be more suitable than phenylephrine for maintaining blood pressure during cesarean section for twins, as phenylephrine causes reflex bradycardia and a resultant decrease in cardiac output. This study was to determine whether norepinephrine was superior to phenylephrine in maintaining maternal hemodynamics during cesarean section for twins. Methods Informed consent was obtained from all the patients before enrollment. In this double-blinded, randomized clinical trial, 100 parturients with twin gestation undergoing cesarean section with spinal anesthesia were randomized to receive prophylactic norepinephrine (3.2 μg/min) or phenylephrine infusion (40 μg/min). The primary outcome was the change of heart rate and blood pressure during the study period. The secondary outcomes were to compare maternal complications, neonatal outcomes, Apgar scores and umbilical blood acid-base status between the two vasopressors. Results There was no significant difference observed for the change of heart rate between two vasopressors. The mean standardized area under the curve of heart rate was 78 ± 12 with norepinephrine vs. 74 ± 11 beats/min with phenylephrine (mean difference 4.4, 95%CI − 0.1 to 9.0; P = .0567). The mean standardized area under the curve of systolic blood pressure (SBP) was significantly lower in parturients with norepinephrine, as the mean of differences in standardized AUC of SBP was 6 mmHg, with a 95% CI from 2 to 9 mmHg (P = .0013). However, requirements of physician interventions for correcting maternal hemodynamical abnormalities (temporary cessation of vasopressor infusion for reactive hypertension, rescuing vasopressor bolus for hypotension and atropine for heart rate less < 50 beats/min) and neonatal outcomes were also not significantly different between two vasopressors. Conclusion Infusion of norepinephrine was not associated with less overall decrease in heart rate during cesarean section for twins, compared with phenylephrine. Trial registration Chinese Clinical Trial Registry (ChiCTR1900021281).

A modified single breath method for estimation of cardiac output in humans at rest and during exercise

1987 ◽  
Vol 72 (4) ◽  
pp. 437-441 ◽  
Author(s):  
Y. M. H. Al-Shamma ◽  
R. Hainsworth ◽  
N. P. Silverton
Keyword(s):  
Cardiac Output ◽  
Normal Subjects ◽  
Random Errors ◽  
O2 Uptake ◽  
Mean Values ◽  
Single Breath ◽  
Expired Gas ◽  
The Mean ◽  
Rest And Exercise ◽  
Single Breath Method

1. This study was undertaken to determine the accuracy of a modification of a single breath method for estimation of cardiac output. The technique incorporated a single rebreathing stage followed by a prolonged expiration. Cardiac output was determined from the O2 uptake and the instantaneous changes in O2 and CO2 in the expired gas during the prolonged expiration. 2. The mean values and the random errors (determined from the differences between pairs of estimates) of cardiac outputs in normal subjects at rest and exercise were 5.42 and ± 0.60 litres/min (2 sd, 60 pairs) and 14.1 and ±1.8 litres/min (40 pairs). 3. Larger random errors were obtained in a group of cardiac patients but, except in hypoxic patients, the mean values obtained by the single breath and the direct (Fick) methods were almost identical. 4. We conclude that our modification of the single breath method is simple to use and sufficiently reliable for use in humans both at rest and during steady states of light exercise.

The effect of progressive hypoxia on respiration in the dogfish (scyliorhinus canicula) at different seasonal temperatures

1975 ◽  
Vol 63 (1) ◽  
pp. 117-130 ◽  
Author(s):  
P. J. Butler ◽  
E. W. Taylor
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Uptake ◽  
Stroke Volume ◽  
Oxygen Tension ◽  
Acclimation Temperature ◽  
Critical Oxygen Tension ◽  
Critical Oxygen ◽  
Progressive Hypoxia ◽  
Cardiac Stroke Volume

1. Dogfish were acclimated to 7, 12 or 17 degrees C and exposed to progressive hypoxia at the temperature to which they had been acclimated. During normoxia, the Q10 values for oxygen uptake, heart rate, cardiac output and respiratory frequency over the full 10 degrees C range were: 2.1, 2.1, 2.1 and 2.5 respectively. Increased acclimation temperature had no effect on cardiac stroke volume or systemic vascular resistance, although there was a decrease in branchial vascular resistance, pHa and pHv. 2. Progressive hypoxia had no effect on heart rate or oxygen uptake at 7 degrees C, whereas at 12 degrees C and 17 degrees C there was bradycardia, and a reduction in O2 uptake, with the critical oxygen tension for both variables being higher at the higher temperature. Cardiac stroke volume increased during hypoxia at each temperature, such that cardiac output did not change significantly at 12 and 17 degrees C. Neither pHa nor pHv changed significantly during hypoxia at any of the three temperatures. 3. The influence of acclimation temperatures on experimental results from poikilotherms is pointed out. Previously-published results show quantitative differences. 4. The significance of the present results with respect to the functioning and location of oxygen receptors is discussed. It is argued that as the metabolic demand and critical oxygen tension of the whole animal are increased at high acclimation temperatures the same must be the case with the oxygen receptor. This would raise the stimulation threshold and could account for the bradycardia seen during hypoxia becoming manifest at higher values of PI,O2, Pa,O2 and Pv,O2 as the acclimation temperature is raised.

The Role of the Cardiac Vagus in the Response of the Dogfish Scyliorhinus Canicula to Hypoxia

1977 ◽  
Vol 70 (1) ◽  
pp. 57-75 ◽  
Author(s):  
E. W. TAYLOR ◽  
S. SHORT ◽  
P. J. BUTLER
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Acclimation Temperature ◽  
Total Blood ◽  
Ventral Aorta ◽  
Branchial Arteries ◽  
Total Blood Flow ◽  
Cardiac Stroke Volume

1. During normoxia, heart rate was governed by a vagal tone which increased at higher acclimation temperatures. This tonic influence was exerted predominantly via the branchial cardiac nerves. The increase in heart rate following atropinization or cardiac vagotomy was associated with a reduction in stroke flow in the ventral aorta in accordance with Starling's Law of the heart. 2. During slowly induced hypoxia there was a reflex bradycardia, the onset and extent of which varied with acclimation temperature, and which was mediated predominantly via the pair of branchial cardiac vagi. The branchial cardiac vagi were also wholely responsible for the transient marked bradycardia at the onset of rapidly induced hypoxia. 3. Direct measurement of blood flow to the anterior two pairs of branchial arteries demonstrated that they received approximately 37% of total cardiac output in normoxia and that this proportion was unchanged during hypoxia. 4. The bradycardia during hypoxia in control animals was partially offset by a rise in cardiac stroke volume so that cardiac output decreased slightly. Injection of the adrenergic -receptor blocker, Propranolol, abolished the increase in stroke flow during hypoxia, but did not effect the bradycardia, and the total blood flow was therefore reduced. 5. The values of PO2 during hypoxia from fish acclimated to 17 °C were significantly reduced from the control values following atropinization and either branchial cardiac vagotomy or total cardiac vagotomy. 6. The apparent power output of the heart was reduced during hypoxia at high acclimation temperatures due to the marked bradycardia.

Evaluation of Cardiac Output by Thoracic Electrical Bioimpedance during Exercise in Normal Subjects

CHEST Journal ◽  
1992 ◽  
Vol 102 (2) ◽  
pp. 448-455 ◽  
Author(s):  
Randy Moore ◽  
Raul Sansores ◽  
Vern Guimond ◽  
Raja Abboud
Keyword(s):  
Cardiac Output ◽  
Normal Subjects ◽  
Thoracic Electrical Bioimpedance ◽  
Electrical Bioimpedance
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