Effects of digoxin on diaphragmatic strength generation

1986 ◽  
Vol 61 (5) ◽  
pp. 1767-1774 ◽  
Author(s):  
M. Aubier ◽  
N. Viires ◽  
D. Murciano ◽  
J. P. Seta ◽  
R. Pariente
Keyword(s):  
Cardiac Output ◽  
Sartorius Muscle ◽  
Transdiaphragmatic Pressure ◽  
Balloon Catheters ◽  
Hindlimb Muscle ◽  
Intramuscular Electrodes ◽  
Plasmatic Level ◽  
Residual Capacity ◽  
Group A ◽  
Group B

Contrary to hindlimb muscle, extracellular calcium plays an important role in diaphragmatic strength generation (J. Appl. Physiol. 58: 2054–61, 1985). Since the inotropic effect of digitalis appears to be related to cell membrane transport of calcium, we studied the effect of digoxin on diaphragmatic contractility in 20 anesthetized dogs. The diaphragm was electrically stimulated with intramuscular electrodes. The transdiaphragmatic pressure (Pdi) during supramaximal (50 V) 2-s stimulations applied over a frequency range of 10–100 Hz was measured with balloon catheters at functional residual capacity. Cardiac output was measured with a Swan-Ganz catheter and diaphragmatic blood flow (Qdi) by timed volume collections of left inferior venous effluent. The force generated by the sartorius muscle during electrical stimulations was studied concomitantly to Pdi. In 10 dogs (group A) 0.04 mg/kg of digoxin was infused in 10 min. In 10 other dogs (group B) 0.2 mg/kg was administered. All measurements were performed during control and 30, 60, 90, and 120 min after digoxin administration. In group A, digoxin plasmatic level at 60 min reached a therapeutic range in all dogs (1.8 +/- 0.3 ng/ml), whereas in group B, digoxin plasmatic level was higher (8 +/- 1.3 ng/ml). No significant change in cardiac output and Qdi was noted after administration of digoxin, either in the dogs of group A or those of group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypocalcemia on diaphragmatic strength generation

1985 ◽  
Vol 58 (6) ◽  
pp. 2054-2061 ◽  
Author(s):  
M. Aubier ◽  
N. Viires ◽  
J. Piquet ◽  
D. Murciano ◽  
F. Blanchet ◽  
...  
Keyword(s):  
Femoral Vein ◽  
Blood Gases ◽  
Ventral Surface ◽  
Sartorius Muscle ◽  
Low Frequencies ◽  
Transdiaphragmatic Pressure ◽  
High Frequencies ◽  
Balloon Catheters ◽  
Arterial Blood ◽  
Residual Capacity

We studied the effects of hypocalcemia on diaphragmatic force and diaphragm blood flow (Qdi) in 12 anesthetized dogs. The diaphragm was electrically stimulated with intramuscular electrodes surgically implanted in the ventral surface of each hemidiaphragm. The transdiaphragmatic pressure (Pdi) during supramaximal (50 V) 2-s stimulations applied over a frequency range of 10–100 Hz was measured with balloon catheters during tracheal occlusion at functional residual capacity. A catheter was placed via the femoral vein into the left inferior phrenic vein, and Qdi was measured by timed volume collections of left inferior venous effluent. A catheter was introduced in a femoral artery to monitor blood pressure (BP). In five additional dogs, the force generated by the sartorius muscle during electrical stimulation was also studied concomitantly to diaphragmatic force. The animals were mechanically ventilated throughout the experiment, and the arterial blood gases and pH were maintained constant. Hypocalcemia was induced by a continuous infusion of EGTA (70 mg X kg-1 X h-1), which led to a progressive decrease (P less than 0.0001) of ionized calcium plasmatic level from 2.21 +/- 0.4 meq/1 during control to 1.69 +/- 0.06, 1.25 +/- 0.5, and 1.07 +/- 0.5 meq/1 after 30, 60, and 120 min, respectively. Hypocalcemia decreased progressively Pdi, which amounted to 84 +/- 3 (P less than 0.001) and 98 +/- 2% of control values for the low frequencies (10 and 20 Hz) and the high frequencies (50 and 100 Hz), respectively, after 30 min of EGTA infusion and to 74 +/- 5 and 79 +/- 6% for the low and high frequencies, respectively, after 120 min.

Respiratory load compensation in chronic airway obstruction

1985 ◽  
Vol 59 (6) ◽  
pp. 1947-1954 ◽  
Author(s):  
M. Lopata ◽  
E. Onal ◽  
G. Cromydas
Keyword(s):  
Airway Obstruction ◽  
Lung Volume ◽  
Average Rate ◽  
Minute Ventilation ◽  
Force Output ◽  
Transdiaphragmatic Pressure ◽  
Load Compensation ◽  
Group A ◽  
Group B ◽  
Chronic Airway

To assess respiratory neuromuscular function and load compensating ability in patients with chronic airway obstruction (CAO), we studied eight stable patients with irreversible airway obstruction during hyperoxic CO2 rebreathing with and without a 17 cmH2O X l-1 X s flow-resistive inspiratory load (IRL). Minute ventilation (VE), transdiaphragmatic pressure (Pdi), and diaphragmatic electromyogram (EMGdi) were monitored. Pdi and EMGdi were obtained via a single gastroesophageal catheter with EMGdi being quantitated as the average rate of rise of inspiratory (moving average) activity. Based on the effects of IRL on the Pdi response to CO2 [delta Pdi/delta arterial CO2 tension (PaCO2)] and the change in Pdi for a given change in EMGdi (delta Pdi/delta EMGdi) during rebreathing, two groups could be clearly identified. Four patients (group A) were able to increase delta Pdi/delta PaCO2 and delta Pdi/delta EMGdi, whereas in the other four (group B) the IRL responses decreased. All group B patients were hyperinflated having significantly greater functional residual capacity (FRC) and residual volume than group A. In addition the IRL induced percent change in delta Pdi/delta PaCO2, and delta VE/delta PaCO2 was negatively correlated with lung volume so that in the hyperinflated group B the higher the FRC the greater was the decrease in Pdi response due to IRL. In both groups the greater the FRC the greater was the decrease in the ventilatory response to loading. Patients with CAO, even with severe airways obstruction, can effect load compensation by increasing diaphragmatic force output, but the presence of increased lung volume with the associated shortened diaphragm prevents such load compensation.

Single Injection Thermodilution

1996 ◽  
Vol 85 (3) ◽  
pp. 481-490. ◽  
Author(s):  
Jos R. C. Jansen ◽  
Jan J. Schreuder ◽  
Jos J. Settels ◽  
Lilian Kornet ◽  
Olaf C. K. M. Penn ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Pulmonary Artery ◽  
Pulmonary Artery Pressure ◽  
Contour Method ◽  
Limits Of Agreement ◽  
Large Variability ◽  
Artery Pressure ◽  
Corrected Equation ◽  
Group A ◽  
Group B

Background Application of the Stewart-Hamilton equation in the thermodilution technique requires flow to be constant. In patients in whom ventilation of the lungs is controlled, flow modulations may occur leading to large errors in the estimation of mean cardiac output. Methods To eliminate these errors, a modified equation was developed. The resulting flow-corrected equation needs an additional measure of the relative changes of blood flow during the period of the dilution curve. Relative flow was computed from the pulmonary artery pressure with use of the pulse contour method. Measurements were obtained in 16 patients undergoing elective coronary artery bypass surgery. In 11 patients (group A), pulmonary artery pressure was measured with a catheter tip transducer, in a partially overlapping group of 11 patients (group B), it was measured with a fluid-filled system. For reference cardiac output we used the proven method of four uncorrected thermodilution estimates equally spread over the ventilatory cycle. Results A total of 208 cardiac output estimates was obtained in group A, and 228 in group B. In group B, 48 estimates could not be corrected because of insufficient pulmonary artery pressure waveform quality from the fluid-filled system. Individual uncorrected Stewart-Hamilton estimates showed a large variability with respect to their mean. In group A, mean cardiac output was 5.01 l/min with a standard deviation of 0.53 l/min, or 10.6%. After flow correction, this scatter decreased to 5.0% (P < 0.0001). With no bias, the corresponding limits of agreement decreased from +/- 1.06 to +/- 0.5 l/min after flow correction. In group B, the scatter decreased similarly and the limits of agreement also became +/- 0.5 l/min after flow correction. Conclusion It was concluded that a single thermodilution cardiac output estimate using the flow-corrected equation is clinically feasible. This is obtained at the cost of a more complex computation and an extra pressure measurement, which often is already available. With this technique it is possible to reduce the fluid load to the patient considerably.

Peripheral Resistance Modulates the Response to Volume Overload in Peritoneal Dialysis Patients

2008 ◽  
Vol 28 (6) ◽  
pp. 604-610 ◽  
Author(s):  
Jun-Ping Tian ◽  
Feng-He Du ◽  
Li-Tao Cheng ◽  
Xin-Kui Tian ◽  
Jonas Axelsson ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Peritoneal Dialysis ◽  
Total Peripheral Resistance ◽  
Important Determinant ◽  
Peripheral Resistance ◽  
Volume Overload ◽  
Fluid Volume ◽  
Parallel Change ◽  
Group A ◽  
Group B

Background Volume overload is thought to be the most important cause of hypertension in peritoneal dialysis (PD) patients. However, there is also evidence that normalization of volume overload is not always accompanied by a drop in blood pressure (BP). In the present study, we hypothesized that dysregulation of peripheral resistance due to endothelial dysfunction would constitute an important determinant of BP response in overhydrated PD patients. Methods We performed an observational, prospective cohort study including all prevalent PD patients at the Peking University Third Hospital between 1 June 2006 and 30 November 2006. After baseline measurements, including echocardiography and bioelectrical impedance analysis, patients fulfilling inclusion criteria were reevaluated after 2 months of follow-up. All patients that exhibited significant changes in BP and extracellular water (ECW) between 2 visits were asked to undergo a second ultrasound. These patients were then divided into group A (parallel change between BP and ECW; n = 12) and group B (paradoxical change between BP and ECW; n = 10). Results The cohort included 22 patients (13 males) with a mean age of 59 ± 13 years, on dialysis for 23.3 ± 32.6 months. There were no baseline differences between groups A and B. However, while patients in group A significantly increased their cardiac output, total peripheral resistance remained stable. In group B, cardiac output did not change significantly but total peripheral resistance decreased significantly. Conclusion In PD patients, a significant increase in fluid volume is not necessarily linked to a significant increase in BP. Rather, the change in total peripheral resistance was found to be the most important determinant of the extent to which increased fluid volume affected BP.

Oxygen tension in the bladder epithelium rises in both high and low cardiac output endotoxemic sepsis

1995 ◽  
Vol 79 (6) ◽  
pp. 1878-1882 ◽  
Author(s):  
D. M. Rosser ◽  
R. P. Stidwill ◽  
D. Jacobson ◽  
M. Singer
Keyword(s):  
Cardiac Output ◽  
Oxygen Tension ◽  
Anaerobic Respiration ◽  
Tissue Oxygen Tension ◽  
Sprague Dawley ◽  
Tissue Oxygen ◽  
Bladder Epithelium ◽  
Low Cardiac Output ◽  
Group A ◽  
Group B

The effect of endotoxin on tissue oxygen tension measured at the bladder epithelium was assessed in spontaneously breathing Sprague-Dawley rats anesthetized with halothane. Hyperdynamic (high cardiac output, group A, n = 6) and hypodynamic (low cardiac output, group B, n = 6) circulatory responses were achieved by intravenous administration of Escherichia coli lipopolysaccharide, 10 mg/kg over 30 min or 20 mg/kg over 1 min, respectively. Comparison was made against sham-operated control rats (group C, n = 6). Aortic and renal blood flows increased in group A and fell in group B (P < 0.001). However, in both groups, bladder epithelial oxygen tension rose significantly compared with control (P < 0.01), despite an increasing metabolic acidosis. This is in contradistinction to previous studies of nonseptic insults where bladder epithelial oxygen tension fell in line with an increasing arterial base deficit. If a raised tissue oxygen tension could be demonstrated in other organ beds, this would suggest that decreased utilization of oxygen rather than reduced tissue oxygen availability is responsible for the apparent anaerobic respiration seen in sepsis.

Effects and mechanism of action of terbutaline on diaphragmatic contractility and fatigue

1984 ◽  
Vol 56 (4) ◽  
pp. 922-929 ◽  
Author(s):  
M. Aubier ◽  
N. Viires ◽  
D. Murciano ◽  
G. Medrano ◽  
Y. Lecocguic ◽  
...  
Keyword(s):  
Low Frequencies ◽  
Transdiaphragmatic Pressure ◽  
High Frequencies ◽  
Balloon Catheters ◽  
Diaphragmatic Fatigue ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Phrenic Nerves ◽  
Indirect Stimulation ◽  
Stimulation Of

We studied the effects of intravenously administered terbutaline on diaphragmatic force and fatigue during electrical stimulation of the diaphragm in 17 anesthetized dogs. The diaphragm was stimulated indirectly through the phrenic nerves with electrodes placed around the fifth roots and directly with electrodes surgically implanted in the abdominal side of each hemidiaphragm. Transdiaphragmatic pressure (Pdi) during direct or indirect supramaximal 2-s stimulation applied over a frequency range of 10–100 Hz was measured with balloon catheters during tracheal occlusion at functional residual capacity. In seven dogs the administration of terbutaline (0.5 mg) had no effect on Pdi at any stimulation frequency applied directly or indirectly. The effect of terbutaline (0.5 mg) on diaphragmatic fatigue was then tested in 10 other dogs. Diaphragmatic fatigue was produced by continuous 20-Hz electrical supramaxial stimulation of the phrenic nerves during 30 min. At the end of the fatigue procedure Pdi decreased by 50 +/- 5 and 30 +/- 8% of control values at 10 and 100 Hz, respectively, for either direct or indirect stimulation. The decrease in Pdi for low frequencies of stimulation (10 and 20 Hz) lasted 100 +/- 18 min, whereas it lasted only 40 +/- 10 min for the high frequencies (50 and 100 Hz). When terbutaline (0.5 mg) was administered after the fatiguing procedure, Pdi increased within 15 min by 20 +/- 4% at 10 Hz and by 12 +/- 3% at 100 Hz for either direct or indirect stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Diaphragmatic contractility enhanced by aminophylline: role of extracellular calcium

1983 ◽  
Vol 54 (2) ◽  
pp. 460-464 ◽  
Author(s):  
M. Aubier ◽  
D. Murciano ◽  
N. Viires ◽  
Y. Lecocguic ◽  
R. Pariente
Keyword(s):  
Transpulmonary Pressure ◽  
Extracellular Calcium ◽  
Phrenic Nerve Stimulation ◽  
Transdiaphragmatic Pressure ◽  
Balloon Catheters ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Phrenic Nerves

We have studied the effects of aminophylline on diaphragmatic contractility in 12 anesthetized dogs. The phrenic nerves were stimulated supramaximally (20 Hz, 0.1 ms) with electrodes placed around the fifth roots, and the transdiaphragmatic pressure (Pdi) generated at functional residual capacity (FRC) was measured with balloon catheters. Constancy of FRC was monitored by measuring the end-expiratory transpulmonary pressure, the dogs being occluded at FRC before the stimulations. The electrical activity of the diaphragm (Edi) during the stimulations was recorded with electrodes inserted in both hemidiaphragms. Phrenic stimulations during an infusion of aminophylline (10 mg/kg in 5 min) increased Pdi by 25 +/- 8% of control values, whereas the Edi remained unchanged. This potentiating effect of aminophylline was abolished when an identical dose was injected during a continuous infusion of a calcium blocker (verapamil, 0.1 mg X kg-1 X min-1). Infusion of another methylxanthine compound, caffeine (10 mg/kg), also increased Pdi for an identical electrical phrenic nerve stimulation by 21 +/- 6% compared with control values. However, the potentiating effect of caffeine was not abolished by verapamil. We conclude that aminophylline in vivo increases diaphragmatic contractility and that extracellular calcium is necessary for this action, a mechanism not shared by another methylxanthine compound, caffeine.

Effect of high-altitude exposure for 10 days on stroke volume and cardiac output

1977 ◽  
Vol 42 (5) ◽  
pp. 722-727 ◽  
Author(s):  
R. S. Hoon ◽  
V. Balasubramanian ◽  
O. P. Mathew ◽  
S. C. Tiwari ◽  
S. C. Sharma ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
High Altitude ◽  
Sea Level ◽  
Impedance Plethysmography ◽  
Noninvasive Technique ◽  
Electrical Impedance Plethysmography ◽  
Group A ◽  
Group B ◽  
Permanent Residents

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0–4 h and 5–8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.

scholarly journals Comparison between cardiac output values measured by thermodilution and partial carbon dioxide rebreathing in patients with acute lung injury

2004 ◽  
Vol 122 (6) ◽  
pp. 233-238 ◽  
Author(s):  
Jorge Luís dos Santos Valiatti ◽  
José Luiz Gomes do Amaral
Keyword(s):  
Carbon Dioxide ◽  
Cardiac Output ◽  
Acute Lung Injury ◽  
Lung Injury ◽  
Lung Injury Score ◽  
Controlled Study ◽  
Carbon Dioxide Rebreathing ◽  
Significant Difference ◽  
Group A ◽  
Group B

CONTEXT: Thermodilution, which is considered to be a standard technique for measuring the cardiac output in critically ill patients, is not free from relevant risks. There is a need to find alternative, noninvasive, automatic, simple and accurate methods for monitoring cardiac output at the bedside. OBJECTIVE: To compare cardiac output measurements by thermodilution and partial carbon dioxide rebreathing in patients with acute lung injury at two levels of severity (lung injury score, LIS: below 2.5, group A; and above 2.5, group B). TYPE OF STUDY: Comparative, prospective and controlled study. SETTING: Intensive Care Units of two university hospitals. METHODS: Cardiac output was measured by thermodilution and partial carbon dioxide rebreathing. Twenty patients with acute lung failure (PaO2/FiO2 < 300) who were under mechanical ventilation and from whom 294 measurements were taken: 164 measurements in group A (n = 11) and 130 in group B (n = 9), ranging from 14 to 15 determinations per patient. RESULTS: There was a poor positive correlation between the methods studied for the patients from groups A (r = 0.52, p < 0.001) and B (r = 0.47, p < 0.001). The application of the Bland-Altman test made it possible to expose the lack of agreement between the methods (group A: -0.9 ± 2.71 l/min; 95% CI = -1.14 to -0.48; and group B: -1.75 ± 2.05 l/min; 95% CI = -2.11 to -1.4). The comparison of the results (Student t and Mann-Whitney tests) within each group and between the groups showed significant difference (p = 0.000, p < 0.05). DISCUSSION: Errors in estimating CaCO2 (arterial CO2 content) from ETCO2 (end-tidal CO2) and situations of hyperdynamic circulation associated with dead space and/or increased shunt possibly explain our results. CONCLUSION: Under the conditions of this study, the results obtained allow us to conclude that, in patients with acute lung injury, the cardiac output determined by partial rebreathing of CO2 differs from the measurements obtained by thermodilution. This difference becomes greater, the more critical the lung injury is.

Effects of small changes of blood volume on oxygen delivery and tissue oxygenation

1981 ◽  
Vol 240 (2) ◽  
pp. H177-H184 ◽  
Author(s):  
I. H. Sarelius ◽  
J. D. Sinclair
Keyword(s):  
Cardiac Output ◽  
Blood Group ◽  
Blood Volume ◽  
Oxygen Delivery ◽  
Metabolic Cost ◽  
Base Line ◽  
Circulatory Effects ◽  
Group A ◽  
Group B ◽  
O2 Delivery

Circulatory effects of small (approximately 10%) changes in blood volume were examined in resting and exercising dogs: controls; group A (-200 ml blood); group B (+200 ml blood); group C (+200 ml 6% dextran). In exercise, cardiac output (Q) increased more in Group A than controls (510.4 ml . kg-1 . min-1 compared to 429.6 ml . kg-1 . min-1; P less than 0.05); oxygen delivery (cardiac output x arterial O2 content) and mixed venous oxygen tension (PVO2) were unchanged from exercising controls. Hypervolemia (group B) did not change Q or O2 delivery compared to controls, but caused a greater reduction in exercise PVO2 (29.3 mmHg compared to 33.1 mmHg in controls; P less than 0.01). Resting PVO2 as raised in group C (50.0 mmHg compared to 46.3 mmHg; P less than 0.05) and exercise PVO2 was reduced less (35.5 mmHg compared to 33.1 mmHg in controls; P less than 0.05). O2 delivery in exercise was higher than in controls (123.4 ml . kg-1 . min-1 compared to 94.3 ml . kg-1 . min-1; P less than 0.001). During exercise, O2 consumption was raised from base line to 34.9 ml . kg-1 . min-1 in controls and raised further to 41.4 ml . kg-1 . min-1 in group A, 44.4 ml . kg-1 . min-1 in group B, and 41.2 ml . kg-1 . min-1 in group C (P less than 0.01). Changes of blood volume that lie within physiological limits thus significantly modify the circulatory response to changed O2 requirements, and also change the metabolic cost of exercise.

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