Cardiac output using an electrically calibrated flow-through conductivity cell.

1974 ◽  
Vol 37 (6) ◽  
pp. 972-977 ◽  
Author(s):  
L A Geddes ◽  
E Peery ◽  
R Steinberg
Keyword(s):  
Cardiac Output ◽  
Flow Through ◽  
Conductivity Cell

Micro-flowcell conductometric sweat analysis for cystic fibrosis diagnosis

2000 ◽  
Vol 37 (3) ◽  
pp. 399-407 ◽  
Author(s):  
H Lewis Webster ◽  
Carmelo G Quirante
Keyword(s):  
Power Supply ◽  
Time Interval ◽  
Sweating Rate ◽  
Sensor Cell ◽  
Sweat Testing ◽  
Small Holders ◽  
Flow Through ◽  
To Receive ◽  
Conductivity Cell ◽  
Sweat Tests

This paper describes a device specifically designed to facilitate neonatal sweat testing. The components are sized appropriately for attachment to the limbs of newborns. Iontophoretic electrodes, with pilocarpine gel inserts, are latched into small holders attached by straps to the limb. The holder at the anodic site remains in place to receive and align the sensor cell, which uses a conical collecting surface to channel the sweat directly and anaerobically from the sweat ducts to the continuous flow-through conductivity cell within its body. A crib-side analysis unit incorporates an iontophoretic power supply and displays a continuous readout of sweat electrical conductivity. The average conductivity during a specific time interval and the initial sweating rate are automatically displayed. The method, which simplifies sweat tests, is currently being assessed in three neonatal clinical trials to test its ability to reduce test failures in the newborn due to insufficient sweat.

CARDIOVASCULAR ADAPTATIONS ENHANCE TOLERANCE OF ENVIRONMENTAL HYPOXIA IN THE CRAB CANCER MAGISTER

1994 ◽  
Vol 190 (1) ◽  
pp. 23-41 ◽  
Author(s):  
C Airriess ◽  
B Mcmahon
Keyword(s):  
Cardiac Output ◽  
Beat Frequency ◽  
Direct Calculation ◽  
Exposure Period ◽  
Heart Beat ◽  
High Rate ◽  
Hypoxic Exposure ◽  
Cancer Magister ◽  
Control Value ◽  
Flow Through

Unrestrained crabs instrumented with probes for ultrasonic measurement of arterial haemolymph flow were subjected to 6 h of hypoxic exposure. During this interval, the inhalant O2 partial pressure was reduced in steps from 18 to 3 kPa. Measurement of haemolymph flow through all arteries leaving the heart allowed direct calculation of cardiac output, stroke volume and the distribution of cardiac output for both non-stressed and hypoxic animals. Resting levels of cardiac output were low compared with previously reported values for this and other species of decapod crustaceans. During exposure to the most severe level of hypoxia tested, haemolymph flow through the anterior arteries decreased while flow through the posterior aorta and sternal artery increased by 55 % and 27 % respectively. Cardiac output increased from a control value of 9.8±1.6 to 11.9±1.2 ml kg-1 min-1 despite a decrease in heart-beat frequency. Scaphognathite beat frequency increased from 82.1±4.3 min-1 to more than 120 min-1 after 90 min of hypoxic exposure and remained at this level for the duration of the exposure period. The decrease in haemolymph flow, via the anterior arteries, to the antero-dorsal region of the animal concurrent with an increase in flow to the posterior and antero-ventral regions, via the posterior aorta and sternal artery, implicates an active mechanism for redistribution of haemolymph flow during hypoxic exposure. The high rate of scaphognathite pumping, presumably to maximise O2 uptake during experimental hypoxia, was probably made possible by an increased blood supply to these organs, which are perfused by downstream branches of the sternal artery.

Application and In situ calibration of a pulsed-doppler flowmeter for blood flow measurement in crustaceans

1994 ◽  
Vol 74 (2) ◽  
pp. 455-458 ◽  
Author(s):  
C.N. Airriess ◽  
B.R. McMahon ◽  
I.J. McGaw ◽  
G.B. Bourne
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
The Body ◽  
Pulsed Doppler ◽  
Arterial Perfusion ◽  
Non Invasive ◽  
In Situ Calibration ◽  
Flow Through ◽  
Doppler Flowmeter

The pulsed-Doppler flowmeter permits continuous, non-invasive measurement of blood flow through several arteries simultaneously. Summation of volume flow rates through all arteries leaving the heart allows determination of cardiac output, stroke volume, and the percentage of cardiac output delivered to each region of the body. The use of this system for investigating changes in arterial perfusion as well as its calibration in situ are described.

Neural influences on the pulmonary vascular bed in man

1989 ◽  
Vol 76 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Paolo Moruzzi ◽  
Paolo Sganzerla ◽  
Maurizio D. Guazzi
Keyword(s):  
Cardiac Output ◽  
Venous Return ◽  
Mental Arithmetic ◽  
Vena Cava ◽  
Cold Pressor ◽  
Diagnostic Procedures ◽  
Adrenergic System ◽  
Physiological Importance ◽  
Arteriolar Resistance ◽  
Flow Through

1. Impedance to venous return by distention of a balloon in the inferior vena cava (IVCB) was utilized in 10 patients, during diagnostic procedures, to reduce blood flow through the lungs at baseline and to buffer its changes during stimulation of the adrenergic system, which was obtained with mental arithmetic (AT) and cold pressor (CPT) tests. 2. When venous return was unimpeded, cardiac output rose by 2.06 1/min during the AT and remained steady during the CPT, and arteriolar resistance in the pulmonary circuit was significantly reduced and slightly raised, respectively. 3. During IVCB, baseline cardiac output decreased by 710 ml/min, it rose by 925 ml/min during the AT and again remained steady during the CPT; pulmonary arteriolar resistance was unchanged from before obstruction at baseline and was significantly augmented by both tests. In particular, AT became a clear vasoconstrictor stimulus, having originally produced vasodilatation. 4. These observations support the view that lung blood vessels in man are sensitive to adrenergic influences and that vasoconstriction can be elicited in circumstances in which the flow through the lungs is restrained. The physiological importance of the neural regulation of the pulmonary circulation in man remains undefined.

Extravascular lung water measurements and hemodynamic monitoring in the critically ill: bedside alternatives to the pulmonary artery catheter

2006 ◽  
Vol 291 (6) ◽  
pp. L1118-L1131 ◽  
Author(s):  
Warren Isakow ◽  
Daniel P. Schuster
Keyword(s):  
Cardiac Output ◽  
Pulmonary Artery ◽  
Pulmonary Artery Catheter ◽  
Critically Ill ◽  
Extravascular Lung Water ◽  
Ejection Time ◽  
Lung Water ◽  
Descending Aorta ◽  
Hemodynamic Management ◽  
Flow Through

The recently completed Fluid and Catheter Treatment Trial conducted by the National Institutes of Health ARDSNetwork casts doubt on the value of routine pulmonary artery catheterization for hemodynamic management of the critically ill. Several alternatives are available, and, in this review, we evaluate the theoretical, validation, and empirical databases for two of these: transpulmonary thermodilution measurements (yielding estimates of cardiac output, intrathoracic blood volume, and extravascular lung water) that do not require a pulmonary artery catheter, and hemodynamic measurements (including estimates of cardiac output and ejection time, a variable sensitive to intravascular volume) obtained by esophageal Doppler analysis of blood flow through the descending aorta. We conclude that both deserve serious consideration as a means of acquiring useful hemodynamic data for managing shock and fluid resuscitation in the critically ill, especially in those with acute lung injury and pulmonary edema, but that additional study, including carefully performed, prospective clinical trials demonstrating outcome benefit, is needed.

Cardiopulmonary response to exercise in patients with intrapulmonary vascular shunts

1993 ◽  
Vol 75 (1) ◽  
pp. 321-328 ◽  
Author(s):  
M. K. Whyte ◽  
J. M. Hughes ◽  
J. E. Jackson ◽  
A. M. Peters ◽  
S. C. Hempleman ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Oxygen Delivery ◽  
Minute Ventilation ◽  
Arterial Oxygen ◽  
Normal Range ◽  
Arterial Pco2 ◽  
Ventilatory Equivalent ◽  
Tissue Oxygen Delivery ◽  
Flow Through ◽  
Response To Exercise

The majority of patients with intrapulmonary right-to-left shunting due to pulmonary arteriovenous malformations-exhibit good maximum exercise capacity (> 70% predicted) despite profound arterial oxygen desaturation. We studied seven such patients to assess tissue oxygen delivery during steady-state exercise. From rest to exercise [50 +/- 7 (SE) W] arterial saturation fell from 80 +/- 3 to 74 +/- 3%, and mean right-to-left shunt increased slightly from 31 +/- 4 to 34 +/- 5% (P = NS). Minute ventilation was high for oxygen uptake, and the ventilatory equivalent was raised (174 +/- 19% predicted) and was correlated with shunt size (r = 0.93). The majority of the patients maintained pulmonary alveolar blood flow within the predicted range for their power output, but total cardiac output was increased to 142 +/- 11% predicted due to flow through the shunt. Consequently, on exercise, oxygen delivery per unit oxygen consumption [2.3–3.3 (normal range 1.6–2.4)] and calculated mixed venous oxygen tension (27.0 +/- 0.8 Torr) were preserved. Arterial PCO2 rose on exercise by 2.8 +/- 1.2 Torr, in proportion to the ratio of flow through the shunt to total cardiac output (r = 0.73), but remained low (33.1 +/- 1.4 Torr) in absolute terms. The high cardiac output on exercise may be facilitated by a low pulmonary vascular resistance (0.33 +/- 0.08 mmHg.1–1.min, measured at rest), which may explain why exercise performance is better in these patients than in patients with equivalent hypoxemia from other causes.

Is the beneficial effect of prior exercise on postprandial lipaemia partly due to redistribution of blood flow?

2011 ◽  
Vol 120 (12) ◽  
pp. 537-548 ◽  
Author(s):  
Nicholas M. Hurren ◽  
George M. Balanos ◽  
Andrew K. Blannin
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cardiac Output ◽  
Portal Vein ◽  
High Fat ◽  
Postprandial Lipaemia ◽  
Postprandial Period ◽  
Hepatic Portal Vein ◽  
Flow Through ◽  
Hepatic Portal

Preprandial aerobic exercise lowers postprandial lipaemia (a risk factor for coronary heart disease); however, the mechanisms responsible are still not clear. The present study investigated whether blood flow to skeletal muscle and/or the liver was increased in the postprandial period after exercise, relative to a control trial, and whether this resulted from increased cardiac output or redistribution of flow. Eight overweight inactive males, aged 49.4±10.5 years (mean±S.D.), acted as their own controls in a counterbalanced design, either walking briskly for 90 min at 60% V̇O2max (maximal oxygen uptake), or resting in the lab, on the evening of day 1. The following morning, a fasting blood sample was collected, participants consumed a high-fat breakfast, and further venous blood samples were drawn hourly for 6 h. Immediately after blood sampling, Doppler ultrasound was used to measure cardiac output and blood flow through both the femoral artery of one leg and the hepatic portal vein, with the ultrasonographer blinded to trial order. The total postprandial triacylglycerol response was 22% lower after exercise (P=0.001). Blood flow through the femoral artery and the hepatic portal vein was increased by 19% (P<0.001) and 16% (P=0.033), respectively, during the 6-h postprandial period following exercise; however, postprandial cardiac output did not differ between trials (P=0.065). Redistribution of blood flow, to both exercised skeletal muscle and the liver, may therefore play a role in reducing the plasma triacylglycerol response to a high-fat meal on the day after an exercise bout.

Non-invasive measurement of cardiac output in heart failure patients using a new foreign gas rebreathing technique

2002 ◽  
Vol 102 (2) ◽  
pp. 247-252 ◽  
Author(s):  
Anders GABRIELSEN ◽  
Regitze VIDEBÆK ◽  
Morten SCHOU ◽  
Morten DAMGAARD ◽  
Jens KASTRUP ◽  
...  
Keyword(s):  
Heart Failure ◽  
Cardiac Output ◽  
Reliable Estimate ◽  
Shunt Flow ◽  
Heart Failure Patients ◽  
Non Invasive ◽  
Patients With Heart Failure ◽  
Flow Through ◽  
The Mean ◽  
Rebreathing Method

Values of effective pulmonary blood flow (QEP) and cardiac output, determined by a non-invasive foreign gas rebreathing method (CORB) using a new infrared photoacoustic gas analysing system, were compared with measurements of cardiac output obtained by the direct Fick (COFICK) and thermodilution (COTD) methods in patients with heart failure or pulmonary hypertension. In 11 patients, of which three had shunt flow through areas without significant gas exchange, the mean difference (bias) and limits of agreement (±2S.D.) were 0.6±1.2litreċmin-1 when comparing COFICK and QEP, and -0.8±1.3litreċmin-1 when comparing COFICK and COTD. When correction for intrapulmonary shunt flow was applied (i.e. calculation of CORB) in all 11 patients, the bias between COFICK and CORB was 0.1±0.9litreċmin-1, primarily because agreement improved in the three patients with significant shunt flow. In the eight patients without significant shunt flow, the agreement between QEP and COFICK was 0.3±0.9litreċmin-1. In conclusion, a foreign gas rebreathing method with a new infrared photoacoustic gas analyser provided at least as reliable a measure of cardiac output as did thermodilution. In the absence of significant shunt flow, measurement of QEP itself provides a reliable estimate of cardiac output in heart failure patients. The infrared photoacoustic gas analyser markedly facilitates clinical use of the rebreathing method in general, which makes the method available to a larger group of clinicians working with patients with cardiovascular diseases.

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