scholarly journals Influence of expiratory loading and hyperinflation on cardiac output during exercise

2004 ◽  
Vol 96 (5) ◽  
pp. 1920-1927 ◽  
Author(s):  
Kristy N. Stark-Leyva ◽  
Ken C. Beck ◽  
Bruce D. Johnson
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Healthy Subjects ◽  
Obstructive Lung Disease ◽  
Intrathoracic Pressure ◽  
Lung Mechanics ◽  
Dynamic Hyperinflation ◽  
Expiratory Flow Limitation ◽  
Lung Inflation

Patients with obstructive lung disease are exposed to expiratory loads (ELs) and dynamic hyperinflation as a consequence of expiratory flow limitation. To understand how these alterations in lung mechanics might affect cardiac function, we examined the influence of a 10-cmH2O EL, alone and in combination with voluntary hyperinflation (ELH), on pulmonary pressures [esophageal (Pes) and gastric (Pg)] and cardiac output (CO) in seven healthy subjects. CO was determined by using an acetylene method at rest and at 40 and 70% of peak work. At rest and during exercise, EL resulted in an increase in Pes and Pg (7-18 cmH2O; P < 0.05) and a decrease in CO (from 5.3 ± 1.8 to 4.5 ± 1.4, 12.2 ± 2.2 to 11.2 ± 2.2, and 16.3 ± 3.3 to 15.2 ± 3.2 l/min for rest, 40% peak work, and 70% peak work, respectively; P < 0.05), which remained depressed after an additional 2 min of EL. With ELH, CO increased at rest and both exercise loads (relative to EL only) but remained below control values. The changes in CO were due to a reduction in stroke volume with a tendency for stroke volume to fall further with prolonged EL. There was a negative correlation between CO and the increase in expiratory Pes and Pg with EL ( R = -0.58 and -0.60; P < 0.01), whereas the rise in CO with subsequent hyperinflation was related to a more negative Pes ( R = 0.72; P < 0.01). In conclusion, EL leads to a reduction in CO, which appears to be primarily related to increases in expiratory abdominal and intrathoracic pressure, whereas ELH resulted in an improved CO, suggesting that lung inflation has little impact on cardiac function.

Breathing through an inspiratory threshold device improves stroke volume during central hypovolemia in humans

2008 ◽  
Vol 104 (5) ◽  
pp. 1402-1409 ◽  
Author(s):  
Kathy L. Ryan ◽  
William H. Cooke ◽  
Caroline A. Rickards ◽  
Keith G. Lurie ◽  
Victor A. Convertino
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Lower Body Negative Pressure ◽  
Systolic Arterial Pressure ◽  
Intrathoracic Pressure ◽  
Subsequent Increase ◽  
Arterial Blood ◽  
Threshold Device ◽  
Inspiratory Resistance

Inspiratory resistance induced by breathing through an impedance threshold device (ITD) reduces intrathoracic pressure and increases stroke volume (SV) in supine normovolemic humans. We hypothesized that breathing through an ITD would also be associated with a protection of SV and a subsequent increase in the tolerance to progressive central hypovolemia. Eight volunteers (5 men, 3 women) were instrumented to record ECG and beat-by-beat arterial pressure and SV (Finometer). Tolerance to progressive lower body negative pressure (LBNP) was assessed while subjects breathed against either 0 (sham ITD) or −7 cmH2O inspiratory resistance (active ITD); experiments were performed on separate days. Because the active ITD increased LBNP tolerance time from 2,014 ± 106 to 2,259 ± 138 s ( P = 0.006), data were analyzed (time and frequency domains) under both conditions at the time at which cardiovascular collapse occurred during the sham experiment to determine the mechanisms underlying this protective effect. At this time point, arterial blood pressure, SV, and cardiac output were higher ( P ≤ 0.005) when breathing on the active ITD rather than the sham ITD, whereas indirect indicators of autonomic activity (low- and high-frequency oscillations of the R-to-R interval) were not altered. ITD breathing did not alter the transfer function between systolic arterial pressure and R-to-R interval, indicating that integrated baroreflex sensitivity was similar between the two conditions. These data show that breathing against inspiratory resistance increases tolerance to progressive central hypovolemia by better maintaining SV, cardiac output, and arterial blood pressures via primarily mechanical rather than neural mechanisms.

scholarly journals Non-Invasive Scale Measurement of Cardiac Output Compared with the Gold-Standard Direct Fick Method: A Feasibility Study

2021 ◽  
Author(s):  
Daniel Yazdi ◽  
Sarin Patel ◽  
Suriya Sridaran ◽  
Evan Wilson ◽  
Sarah Smith ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Exercise Test ◽  
Gold Standard ◽  
Cardiopulmonary Exercise Test ◽  
Cardiac Monitoring ◽  
Non Invasive ◽  
Cardiopulmonary Exercise ◽  
The Mean

AbstractBackgroundObjective markers of cardiac function are limited in the outpatient setting and may be beneficial for monitoring patients with chronic cardiac conditions.ObjectiveWe assess the accuracy of a scale, with the ability to capture ballistocardiography, electrocardiography, and impedance plethysmography signals from a patient’s feet while standing on the scale, in measuring stroke volume and cardiac output compared to the gold-standard direct Fick method.MethodsThirty-two patients with unexplained dyspnea undergoing level 3 invasive cardiopulmonary exercise test at a tertiary medical center were included in the final analysis. We obtained scale and direct Fick measurements of stroke volume and cardiac output before and immediately after invasive cardiopulmonary exercise test.ResultsStroke volume and cardiac output from a cardiac scale and the direct Fick method correlated with r = 0.81 and r = 0.85, respectively (P < 0.001 each). The mean absolute error of the scale estimated stroke volume was -1.58 mL, with a 95% limits of agreement (LOA) of -21.97 mL to 18.81 mL. The mean error for the scale estimated cardiac output was -0.31 L/min, with a 95% LOA of -2.62 L/min to 2.00 L/min. The change in stroke volume and cardiac output before and after exercise were 78.9% and 96.7% concordant, respectively between the two measuring methods.ConclusionsThis novel scale with cardiac monitoring abilities may allow for non-invasive, longitudinal measures of cardiac function. Using the widely accepted form factor of a bathroom scale, this method of monitoring can be easily integrated into a patient’s lifestyle.

Heart–lung interactions

2020 ◽  
pp. 73-80
Author(s):  
Gulrukh Zaidi ◽  
Paul H. Mayo
Keyword(s):  
Critical Care ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Transthoracic Echocardiography ◽  
Intrathoracic Pressure ◽  
Practical Method ◽  
Pressure Variation ◽  
Respiratory Cycle ◽  
Critical Care Echocardiography ◽  
Pulsed Wave Doppler

Echocardiography is the most clinically practical method of visualizing cardiac structures and directly observing changes of cardiac function during the respiratory cycle. This chapter will review heart–lung interactions and will focus on the effects of intrathoracic pressure variation on cardiac function that can be measured with advanced critical care echocardiography. These measurements are derived from observing respirophasic variation of stroke volume (SV) and help the intensivist to guide management of haemodynamic failure. The heart–lung interactions that occur with changes in intrathoracic pressure variation have utility in identification of preload sensitivity and adverse patient ventilator interaction. Measurement of the systolic velocity envelope with pulsed-wave Doppler is a requisite skill in order to identify SV variation, as is the recognition that the measurements may be difficult with transthoracic echocardiography.

Dynamic Hyperinflation and Intrinsic Positive End-Expiratory Pressure

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Adverse Effects ◽  
Obstructive Lung Disease ◽  
Airflow Obstruction ◽  
Intrinsic Peep ◽  
Dynamic Hyperinflation ◽  
Positive End Expiratory Pressure ◽  
Inspiratory Time ◽  
Pulmonary Barotrauma

Dynamic hyperinflation and intrinsic PEEP almost always occur in patients with severe obstructive lung disease, in whom slowing of expiratory flow prevents complete exhalation. Occasionally, patients without airflow obstruction develop dynamic hyperinflation when expiratory time, is excessively shortened by a rapid respiratory rate, a long set inspiratory time (TI), or both. Dynamic Hyperinflation and Intrinsic Positive End-Expiratory Pressure describes the causes of dynamic hyperinflation and the mechanisms of its adverse effects, including reduced cardiac output and blood pressure, pulmonary barotrauma, and ineffective ventilator triggering. The chapter also describes how to screen for and measure intrinsic PEEP, and how to reduce or eliminate its adverse effects.

Acute plasma expansion: left ventricular hemodynamics and endocrine function during exercise

1992 ◽  
Vol 73 (5) ◽  
pp. 1791-1796 ◽  
Author(s):  
I. L. Kanstrup ◽  
J. Marving ◽  
P. F. Hoilund-Carlsen
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Healthy Subjects ◽  
Venous Pressure ◽  
Left Ventricular ◽  
Endocrine Function ◽  
Plasma Expansion ◽  
Central Venous ◽  
Mean Pressure ◽  
Dextran Solution

In 11 healthy subjects (8 males and 3 females, age 21–59 yr) left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes were measured in the supine position by isotope cardiography at rest and during two submaximal one-legged exercise loads before and 1 h after acute plasma expansion (PE) by use of a 6% dextran solution (500–750 ml). After PE, blood volume increased from 5.22 +/- 0.92 to 5.71 +/- 1.02 (SD) liters (P < 0.01). At rest, cardiac output increased 30% (5.3 +/- 1.0 to 6.9 +/- 1.6 l/min; P < 0.01), stroke volume increased from 90 +/- 20 to 100 +/- 28 ml (P < 0.05), and LVEDV increased from 134 +/- 29 to 142 +/- 40 ml (NS). LVESV was unchanged (44 +/- 11 and 42 +/- 14 ml). Heart rate rose from 60 +/- 7 to 71 +/- 10 beats/min (P < 0.01). The cardiac preload [central venous pressure (CVP)] was insignificantly elevated (4.9 +/- 2.1 and 5.3 +/- 3.0 mmHg); systemic vascular resistance and arterial pressures were significantly reduced (mean pressure fell from 91 +/- 11 to 85 +/- 11 mmHg, P < 0.01). Left ventricular peak filling and peak ejection rates both increased (19 and 14%, respectively; P < 0.05). During exercise, cardiac output remained elevated after PE compared with the control situation, predominantly due to a 10- to 14-ml rise in stroke volume caused by an increased LVEDV, whereas LVESV was unchanged. CVP increased after PE by 2.1 and 3.0 mmHg, respectively (P < 0.05).2+ remained unchanged during exercise compared with rest after PE in

Leg crossing improves orthostatic tolerance in healthy subjects: a placebo-controlled crossover study

2006 ◽  
Vol 291 (4) ◽  
pp. H1768-H1772 ◽  
Author(s):  
C. T. Paul Krediet ◽  
Johannes J. van Lieshout ◽  
Lysander W. J. Bogert ◽  
Rogier V. Immink ◽  
Yu-Sok Kim ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Crossover Study ◽  
Healthy Subjects ◽  
Lower Body Negative Pressure ◽  
Vasovagal Syncope ◽  
Orthostatic Tolerance ◽  
Healthy Human

Vasovagal syncope is the most common cause of transient loss of consciousness, and recurrent vasovagal fainting has a profound impact on quality of life. Physical countermaneuvers are applied as a means of tertiary prevention but have so far only proven useful at the onset of a faint. This placebo-controlled crossover study tested the hypothesis that leg crossing increases orthostatic tolerance. Nine naïve healthy subjects [6 females, median age 25 yr (range 20–41 yr), mean body mass index 23 (SD 2)] were subjected to passive head-up tilt combined with a graded lower body negative pressure challenge (20, 40, and 60 mmHg) determining orthostatic tolerance thrice, in randomized order: 1) control, 2) with leg crossing, and 3) with oral placebo. Blood pressure (Finometer), heart rate, and changes in thoracic blood volume (impedance), stroke volume, and cardiac output (Modelflow) were followed during orthostatic stress. Primary outcome was time to presyncope (systolic blood pressure ≤85 mmHg, heart rate ≥140 beats/min). With leg crossing, orthostatic tolerance increased from 26 ± 2 to 34 ± 2 min (placebo 23 ± 3 min, P < 0.001). During leg crossing, mean arterial pressure (81 vs. 81 mmHg) and cardiac output (95 vs. 94% supine) remained unchanged; heart rate increase was lower (13 vs. 18 beats/min, P < 0.05); stroke volume was higher (79 vs. 74% supine, P < 0.05); and there was a trend toward lower thoracic impedance. Leg crossing increases orthostatic tolerance in healthy human subjects. As a measure of prevention, it is a worthwhile addition to the management of vasovagal syncope.

Differential effects of endothelin-1 on isolated working rat hearts before and after ischaemia and reperfusion

2002 ◽  
Vol 103 (s2002) ◽  
pp. 189S-193S ◽  
Author(s):  
Andrew T. GOODWIN ◽  
Mohamed AMRANI ◽  
Caroline C. GRAY ◽  
Jay JAYAKUMAR ◽  
Adrian J. MARCHBANK ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Physiological Role ◽  
Rate Of Change ◽  
Cardioplegic Arrest ◽  
Beneficial Effects ◽  
Rat Hearts ◽  
Before And After ◽  
Dose Dependent Decrease

Endothelin (ET) may have both detrimental (reduced coronary flow) and beneficial effects (positive inotrope, reduced arrhythmogenesis) following ischaemia. We examined the effects of ET on cardiac function during reperfusion following prolonged hypothermic cardioplegic arrest in a protocol mimicking cardiac transplantation. Isolated working rat hearts were perfused with Krebs buffer to which increasing concentrations of ET-1 or sarafotoxin S6c had been added. Identical experiments were performed after 4h of cardioplegic arrest at 4°C. Under pre-ischaemic conditions ET-1 caused a dose-dependent decrease in cardiac function compared with controls. In contrast, following ischaemia low doses of ET-1 (10-10 M) caused a significant and beneficial increase in cardiac output (109.1% versus 81.3%), dP/dt i.e. the rate of change of pressure with time (94.7% versus 75.6%) and stroke volume (100.3% versus 77.5%) compared with controls (P<0.05). At higher doses of ET-1 there was a detrimental effect on cardiac output, dP/dt and stroke volume similar to that seen prior to ischaemia. Sarafotoxin S6c had no significant effect pre or post ischaemia on any of the parameters measured compared with controls (P = not significant). ET-1 at low concentrations during reperfusion can improve the recovery of cardiac function mediated via ETA receptors. ET may play an important physiological role in the recovery of cardiac function following prolonged ischaemia.

scholarly journals CARDIAC FUNCTION DURING MINI-INVASIVE REPAIR OF PECTUS EXCAVATUM WITH THE NUSS PROCEDURE

2021 ◽  
Vol 74 (8) ◽  
pp. 1809-1815
Author(s):  
Ulbolhan A. Fesenko ◽  
Ivan Myhal
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Index ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Epidural Anaesthesia ◽  
Pectus Excavatum ◽  
Stroke Volume Index ◽  
Volume Index ◽  
Nuss Procedure

The aim of the study was to analyze cardiac function during Nuss procedure under the combination of general anesthesia with different variants of the regional block. Materials and methods: The observative prospective study included 60 adolescents (boys/girls=47/13) undergone Nuss procedure for pectus excavatum correction under the combination of general anaesthesia and regional blocks. The patients were randomized into three groups (n=20 in each) according to the perioperative regional analgesia technique: standart epidural anaesthesia (SEA), high epidural anaesthesia (HEA) and bilateral paravertebral anaesthesia (PVA). The following parameters of cardiac function were analyzed: heart rate, estimated cardiac output (esCCO), cardiac index (esCCI), stroke volume (esSV) and stroke volume index (esSVI) using non-invasive monitoring. Results: Induction of anesthesia and regional blocks led to a significant decrease in esCCO (-9.4%) and esCCI (-9.8%), while esSV and esSVI remained almost unchanged in all groups (H=4.9; p=0.09). At this stage, the decrease in cardiac output was mainly due to decreased heart rate. At the stage of sternal elevation we found an increase in esSV, which was more pronounced in the groups of epidural blocks (+23.1% in HEA and +18.5% in SEA). After awakening from anesthesia and tracheal extubation esSV was by 11% higher than before surgery without ingergroup difference. Conclusions: The Nuss procedure for pectus excavatum correction lead to improved cardiac function. increase in stroke volume and its index were more informative than cardiac output and cardiac index which are dependent on heart rate that is under the influence of anaesthesia technique.

Myocardial function in rat genetic models of low and high aerobic running capacity

2002 ◽  
Vol 282 (3) ◽  
pp. R721-R726 ◽  
Author(s):  
John C. Barbato ◽  
Soon Jin Lee ◽  
Lauren Gerard Koch ◽  
George T. Cicila
Keyword(s):  
Cardiac Output ◽  
Stroke Volume ◽  
Cardiac Function ◽  
Atp Hydrolysis ◽  
Mrna Level ◽  
Inbred Strains ◽  
Left Ventricular ◽  
Genetic Models ◽  
Heart Preparation ◽  
The Mean

We recently evaluated treadmill aerobic running capacity in 11 inbred strains of rats and found that isolated working left ventricular function correlated ( r = 0.86) with aerobic running capacity. Among these 11 strains the Buffalo (BUF) hearts produced the lowest and the DA hearts the highest isolated cardiac output. The goal of this study was to investigate the components of cardiac function (i.e., coronary flow, heart rates, stroke volume, contractile dynamics, and cross-bridge cycling) to characterize further the BUF and DA inbred strains as potential models of contrasting myocardial performance. Cardiac performance was assessed using the Langendorff-Neely working heart preparation. Isolated DA hearts were superior ( P< 0.05) to the BUF hearts for cardiac output (63%), stroke volume (60%), aortic +dP/d t (47%), and aortic −dP/d t(46%). The mean α/β-myosin heavy chain (MHC) isoform ratio for DA hearts was 21-fold higher relative to BUF hearts. At the steady-state mRNA level, DA hearts had a fivefold higher α/β-ratio than the BUF hearts. The mean rate of ATP hydrolysis by MHCs was 64% greater in DA compared with BUF ventricles. These data demonstrate that the BUF and DA strains can serve as genetic models of contrasting low and high cardiac function.

Dynamics of Circulatory Adjustments to Head-Up Tilt and Tilt-Back in Healthy and Sympathetically Denervated Subjects

1998 ◽  
Vol 94 (4) ◽  
pp. 347-352 ◽  
Author(s):  
W. Wieling ◽  
J. J. Van Lieshout ◽  
A. D. J. Ten Harkel
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Healthy Subjects ◽  
Mean Blood Pressure ◽  
Head Up Tilt ◽  
Change In Mean

1. The initial circulatory adjustments induced by head-up tilt and tilt-back were investigated in six healthy subjects (aged 30–58 years) and six patients with orthostatic hypotension due to pure autonomic failure (aged 33–65 years). 2. Continuous responses of finger arterial pressure and heart rate were recorded by Finapres. A pulse contour algorithm applied to the arterial pressure waveform was used to compute stroke volume responses. 3. In the healthy subjects, head-up tilt induced gradual circulatory adjustments. After 1 min upright stroke volume and cardiac output had decreased by 39 ± 9% and 26 ± 10% respectively. Little change in mean blood pressure at heart level (+1 ± 7 mmHg) indicated that systemic vascular resistance had increased by 39 ± 24%. The gradual responses to head-up tilt contrasted with the pronounced and rapid circulatory responses upon tilt-back. After 2–3 s a rapid increase in stroke volume (from 62 ± 8% to 106 ± 10%) and cardiac output (from 81 ± 11% to 118 ± 20%) was observed with an overshoot of mean arterial pressure above supine control values of 16 ± 3 mmHg at 7 s. In the patients a progressive fall in blood pressure on head-up tilt was observed. After 1 min upright mean blood pressure had decreased by 59 ± 8 mmHg. No change in systemic vascular resistance and a larger decrease in stroke volume (60 ± 7%) and cardiac output (53 ± 8%) were found. On tilt-back a gradual recovery of blood pressure was observed. 4. In healthy humans upon head-up tilt neural compensatory mechanisms are very effective in maintaining arterial pressure at heart level. The gradual circulatory adjustments to head-up tilt in healthy subjects contrast with the pronounced and abrupt circulatory changes on tilt-back. In patients with a lack of neural circulatory reflex adjustments, gradual blood pressure decreases to head-up tilt and gradual increases to tilt-back are observed.

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