Critical Oxygen Delivery in Conscious Humans Is Less Than 7.3 ml O2· kg−1· min−1

2000 ◽  
Vol 92 (2) ◽  
pp. 407-407 ◽  
Author(s):  
Jeremy A. Lieberman ◽  
Richard B. Weiskopf ◽  
Scott D. Kelley ◽  
John Feiner ◽  
Mariam Noorani ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Index ◽  
Stroke Volume ◽  
Oxygen Delivery ◽  
Lactate Concentration ◽  
Stroke Volume Index ◽  
Volume Index ◽  
Plasma Lactate ◽  
Autologous Plasma ◽  
Adrenergic Antagonist

Background The "critical" level of oxygen delivery (DO2) is the value below which DO2 fails to satisfy the metabolic need for oxygen. No prospective data in healthy, conscious humans define this value. The authors reduced DO2 in healthy volunteers in an attempt to determine the critical DO2. Methods With Institutional Review Board approval and informed consent, the authors studied eight healthy, conscious volunteers, aged 19-25 yr. Hemodynamic measurements were obtained at steady state before and after profound acute isovolemic hemodilution with 5% albumin and autologous plasma, and again at the reduced hemoglobin concentration after additional reduction of DO2 by an infusion of a beta-adrenergic antagonist, esmolol. Results Reduction of hemoglobin from 12.5+/-0.8 g/dl to 4.8+/-0.2 g/dl (mean +/- SD) increased heart rate, stroke volume index, and cardiac index, and reduced DO2 (14.0+/-2.9 to 9.9+/-20 ml O2 x kg(-1) x min(-1); all P<0.001). Oxygen consumption (VO2; 3.0+/-0.5 to 3.4+/-0.6 ml O2 x kg(-1) x min(-1); P<0.05) and plasma lactate concentration (0.50+/-0.10 to 0.62+/-0.16 mM; P<0.05; n = 7) increased slightly. Esmolol decreased heart rate, stroke volume index, and cardiac index, and further decreased DO2 (to 7.3+/-1.4 ml O2 x kg(-1) x min(-1); all P<0.01 vs. before esmolol). VO2 (3.2+/-0.6 ml O2 x kg(-1) x min(-1); P>0.05) and plasma lactate (0.66+/-0.14 mM; P>0.05) did not change further. No value of plasma lactate exceeded the normal range. Conclusions A decrease in DO2 to 7.3+/-1.4 ml O2 x kg(-1) min(-1) in resting, healthy, conscious humans does not produce evidence of inadequate systemic oxygenation. The critical DO2 in healthy, resting, conscious humans appears to be less than this value.

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.

scholarly journals Cardiovascular Changes during Deep Halothane Anaesthesia in Infants and Children

1988 ◽  
Vol 16 (3) ◽  
pp. 285-291 ◽  
Author(s):  
J. Tibballs ◽  
S. Malbezin
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Index ◽  
Stroke Volume ◽  
Stroke Volume Index ◽  
Left Ventricular ◽  
Infants And Children ◽  
Volume Index ◽  
Induction Of Anaesthesia

Cardiac output, blood pressure and heart rate were measured with noninvasive techniques before, during and after induction of anaesthesia with halothane and after intubation in unpremedicated infants and in diazepam-atropine premedicated children presenting for elective surgery. Cardiac output was measured with pulsed doppler echocardiography. Left ventricular shortening fraction was estimated with M-mode echocardiography during induction. Induction with halothane in infants caused significant decrements in blood pressure, cardiac index, stroke volume index and significant depression of left ventricular shortening fraction. Induction with halothane in diazepam-atropine premedicated children caused a significant increase in heart rate but significant decreases in blood pressure, stroke volume index and left ventricular shortening fraction while cardiac index decreased slightly. Intubation in infants caused a mild increase in heart rate compared with pre-induction values but blood pressure, cardiac index and stroke volume index remained below pre-induction values. Intubation in diazepam-atropine premedicated children caused significant increases in heart rate and cardiac index, and a nonsignificant increase in blood pressure but stroke volume index remained significantly below pre-induction values. Healthy infants and children tolerate induction of anaesthesia with halothane to a depth to permit intubation but large reductions in cardiac output and myocardial contractility are expected with subsequent reductions in blood pressure.

Cardiovascular Responses to Induction of Anaesthesia with Thiopentone and Suxamethonium in Infants and Children

1988 ◽  
Vol 16 (3) ◽  
pp. 278-284 ◽  
Author(s):  
J. Tibballs ◽  
S. Malbezin
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Cardiac Index ◽  
Stroke Volume ◽  
Systolic Blood Pressure ◽  
Stroke Volume Index ◽  
Infants And Children ◽  
Volume Index ◽  
Induction Of Anaesthesia

Cardiac output, systolic blood pressure and heart rate were measured with non-invasive techniques before, during and after induction of anaesthesia with thiopentone (7.5–8.5 mg/kg) and suxamethonium (1.4–1.7 mg/kg), and after intubation in unpremedicated infants and diazepam-atropine premedicated children. Cardiac output was measured with a combination of M-mode and pulsed doppler echocardiography. Significant decreases in systolic blood pressure, cardiac index and stroke volume index were observed during induction in both infants and children. Intubation caused increases above pre-induction levels of heart rate, blood pressure and cardiac index in both infants and children. Stroke volume index increased marginally in infants but remained depressed in children after intubation. Left ventricular shortening fraction decreased significantly in five other children during induction. It is concluded that thiopentone causes significant reduction in cardiac output by depression of myocardial contractility manifested by depression of blood pressure and stroke volume. Premedication with atropine may ameliorate reduction in cardiac output by permitting an increase in heart rate during induction. Induction of anaesthesia with thiopentone and premedication with diazepam does not prevent hypertension and tachycardia occurring with intubation.

scholarly journals A proof of principle study of atomoxetine for the prevention of vasovagal syncope: the Prevention of Syncope Trial VI

EP Europace ◽  
2019 ◽  
Vol 21 (11) ◽  
pp. 1733-1741 ◽  
Author(s):  
Robert S Sheldon ◽  
Lucy Lei ◽  
Juan C Guzman ◽  
Teresa Kus ◽  
Felix A Ayala-Paredes ◽  
...  
Keyword(s):  
Cardiac Index ◽  
Stroke Volume ◽  
Vasovagal Syncope ◽  
Resistance Index ◽  
Stroke Volume Index ◽  
Study Drug ◽  
Norepinephrine Transporter ◽  
Volume Index ◽  
Head Up Tilt ◽  
Invasive Techniques

Abstract Aims There are few effective therapies for vasovagal syncope (VVS). Pharmacological norepinephrine transporter (NET) inhibition increases sympathetic tone and decreases tilt-induced syncope in healthy subjects. Atomoxetine is a potent and highly selective NET inhibitor. We tested the hypothesis that atomoxetine prevents tilt-induced syncope. Methods and results Vasovagal syncope patients were given two doses of study drug [randomized to atomoxetine 40 mg (n = 27) or matched placebo (n = 29)] 12 h apart, followed by a 60-min drug-free head-up tilt table test. Beat-to-beat heart rate (HR), blood pressure (BP), and cardiac haemodynamics were recorded using non-invasive techniques and stroke volume modelling. Patients were 35 ± 14 years (73% female) with medians of 12 lifetime and 3 prior year faints. Fewer subjects fainted with atomoxetine than with placebo [10/29 vs. 19/27; P = 0.003; risk ratio 0.49 (confidence interval 0.28–0.86)], but equal numbers of patients developed presyncope or syncope (23/29 vs. 21/27). Of patients who developed only presyncope, 87% (13/15) had received atomoxetine. Patients with syncope had lower nadir mean arterial pressure than subjects with only presyncope (39 ± 18 vs. 69 ± 18 mmHg, P < 0.0001), and this was due to lower trough HRs in subjects with syncope (67 ± 30 vs. 103 ± 32 b.p.m., P = 0.006) and insignificantly lower cardiac index (2.20 ± 1.36 vs. 2.84 ± 1.05 L/min/m2, P = 0.075). There were no significant differences in stroke volume index (32 ± 6 vs. 35 ± 5 mL/m2, P = 0.29) or systemic vascular resistance index (2156 ± 602 vs. 1790 ± 793 dynes*s/cm5*m2, P = 0.72). Conclusion Norepinephrine transporter inhibition significantly decreased the risk of tilt-induced syncope in VVS subjects, mainly by blunting reflex bradycardia, thereby preventing final falls in cardiac index and BP.

scholarly journals Stress Echocardiography in Hyperthyroidism

1999 ◽  
Vol 84 (7) ◽  
pp. 2308-2313 ◽  
Author(s):  
George J. Kahaly ◽  
Stephan Wagner ◽  
Jana Nieswandt ◽  
Susanne Mohr-Kahaly ◽  
Thomas J. Ryan
Keyword(s):  
Heart Rate ◽  
Ejection Fraction ◽  
Stroke Volume ◽  
Stress Echocardiography ◽  
Maximal Exercise ◽  
Stroke Volume Index ◽  
Work Load ◽  
Left Ventricular ◽  
Volume Index ◽  
Systolic Volume

Exertion symptoms occur frequently in subjects with hyperthyroidism. Using stress echocardiography, exercise capacity and global left ventricular function can be assessed noninvasively. To evaluate stress-induced changes in cardiovascular function, 42 patients with untreated thyrotoxicosis were examined using exercise echocardiography. Studies were performed during hyperthyroidism, after treatment with propranolol, and after restoration of euthyroidism. Twenty- two healthy subjects served as controls. Ergometry was performed with patients in a semisupine position using a continuous ramp protocol starting at 20 watts/min. In contrast to control and euthyroidism, the change in end-systolic volume index from rest to maximal exercise was lower in hyperthyroidism. At rest, the stroke volume index, ejection fraction, and cardiac index were significantly increased in hyperthyroidism, but exhibited a blunted response to exercise, which normalized after restoration of euthyroidism. Propranolol treatment also led to a significant increase of delta (Δ) stroke volume index. Maximal work load and Δ heart rate were markedly lower in hyper- vs. euthyroidism. Compared to the control value, systemic vascular resistance was lowered by 36% in hyperthyroidism at rest, but no further decline was noted at maximal exercise. The Δ stroke volume index, Δ ejection fraction, Δ heart rate, and maximal work load were significantly reduced in severe hyperthyroidism. Negative correlations between free T3 and diastolic blood pressure, maximal work load, Δ heart rate, and Δ ejection fraction were noted. Thus, in hyperthyroidism, stress echocardiography revealed impaired chronotropic, contractile, and vasodilatatory cardiovascular reserves, which were reversible when euthyroidism was restored.

Cardiovascular responses to exhaustive upright cycle exercise in highly trained older men

1994 ◽  
Vol 77 (3) ◽  
pp. 1500-1506 ◽  
Author(s):  
J. L. Fleg ◽  
S. P. Schulman ◽  
F. C. O'Connor ◽  
G. Gerstenblith ◽  
L. C. Becker ◽  
...  
Keyword(s):  
Cardiac Index ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Stroke Volume Index ◽  
Cardiovascular Responses ◽  
Radionuclide Ventriculography ◽  
Volume Index ◽  
Heart Rates ◽  
Peak Vo2

It is unclear whether the markedly enhanced aerobic exercise capacity of older endurance-trained men relative to their sedentary age peers is mediated primarily by central or peripheral cardiovascular mechanisms. To address this question, we performed radionuclide ventriculography with respiratory gas exchange measurements during exhaustive upright cycle ergometry in 16 endurance-trained men aged 63 +/- 7 yr and in 35 untrained men of similar age. As expected, maximal O2 consumption during treadmill exercise was much higher in athletes than in controls. At rest and during fixed submaximal cycle work rates through 100 W, athletes demonstrated lower heart rates and greater stroke volume indexes than controls while maintaining similar cardiac indexes and O2 uptake (VO2). At exhaustion, athletes achieved 53% higher work rates and peak VO2 per kilogram body weight than the sedentary men. The higher peak VO2 in athletes was achieved by a 22.5% larger cardiac index and a 15.6% greater arteriovenous O2 difference. The larger peak cardiac index in the athletes than in sedentary controls was mediated entirely by a greater stroke volume index; peak heart rates were virtually identical. The athletes' greater stroke volume index was achieved through an 11% larger end-diastolic volume index and a 7% higher ejection fraction, both of borderline significance. At exhaustion, athletes demonstrated a lower systemic vascular resistance than controls, despite a higher value at rest. Athletes also showed greater exercise-induced increments in heart rate, stroke volume index, and cardiac index and a greater reduction in systemic vascular resistance from rest to maximal workload.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effect of heart rate control with amiodarone infusion on hemodynamic and clinical outcomes in septic shock patients with tachycardia: a prospective, single-arm clinical study

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Masoud Khataminia ◽  
Farhad Najmeddin ◽  
Atabak Najafi ◽  
Hamidreza Sharifnia ◽  
Arezoo Ahmadi ◽  
...  
Keyword(s):  
Heart Rate ◽  
Septic Shock ◽  
Cardiac Index ◽  
Rate Control ◽  
Stroke Volume Index ◽  
Volume Index ◽  
Target Heart Rate ◽  
Norepinephrine Infusion ◽  
Hemodynamic State ◽  
Refractory Hypotension

Abstract Background Keeping the heart rate within the normal range has improved the survival of septic shock patients. Amiodarone could target the underlying pathophysiology of sepsis-induced tachycardia. This study aimed to determine whether amiodarone is effective in controlling the heart rate in critically ill patients with septic shock and sustained tachycardia who were receiving vasopressor. Methods In this prospective, single-arm cohort study, 46 patients with septic shock and tachycardia were enrolled to receive a loading dose of amiodarone 150 mg, then continuous infusion of 1 mg/min. The primary outcome was the ability of amiodarone in rate control lower than 95 beats per minute (BPM) and maintaining it during 24-h study period. We also recorded the effect of amiodarone on hemodynamic indices as the secondary outcomes. Results The results of the present study indicated a significant decrease in HR in septic shock patients for amiodarone, from 121.0 (116.5, 140.0) at baseline to 91.5(89.3, 108.0) at the end of the study period (p < 0.001). During the study period, a total of 26 (56.52%) of patients achieved the target heart rate lower than 95 BPM and maintained it during study period. Amiodarone decreased HR by 22.8 ± 13.7. While receiving amiodarone infusion, the values for heart rate, mean arterial pressure, cardiac index, norepinephrine infusion rate, and stroke volume index changed significantly between amiodarone initiation and 24-h follow-up (P < 0.001). Amiodarone was well tolerated, because this anti-arrhythmic agent did not increase the need for vasopressor and none of the patients experienced episodes of refractory hypotension. Conclusion This study showed that amiodarone infusion successfully reduced the heart rate in sepsis-induced tachycardia. The patients had improved hemodynamic state as indicated by an increase in cardiac index and SVI.

scholarly journals Non-Invasive Estimation of Cardiac Index in Healthy Volunteers

2018 ◽  
Vol 46 (3) ◽  
pp. 290-296 ◽  
Author(s):  
C. T. Eyeington ◽  
P. Ancona ◽  
L. Cioccari ◽  
N. Luethi ◽  
N. J. Glassford ◽  
...  
Keyword(s):  
Cardiac Index ◽  
Stroke Volume ◽  
Healthy Volunteers ◽  
Resistance Index ◽  
Stroke Volume Index ◽  
Primary Objective ◽  
Volume Index ◽  
Haemodynamic Parameters ◽  
Healthy Humans ◽  
The Mean

The primary objective was to non-invasively measure the cardiac index (CI) and associated haemodynamic parameters of healthy volunteers and their changes with age. This was a single centre, prospective, observational study of healthy volunteers aged between 20 and 59 years, using the ClearSight™ (Edwards Life Sciences, Irvine, CA, USA) device. We recorded 514 observations in 97 participants. The mean CI was 3.5 l/min/m2 (95% confidence interval [95% CI] 3.4 to 3.7 l/min/m2). The mean stroke volume index (SVI) was 47 ml/m2 (95% CI 45 to 49 ml/m2) and the mean systemic vascular resistance index was 2,242 dyne·s/cm5/m2 (95% CI 2,124 to 2,365 dyne·s/cm5/m2). There was an inverse linear relationship between increasing age and CI (P <0.0001), which decreased by 0.044 l/min/m2 (95% CI −0.032 to −0.056 l/min/m2) per year. This change was mostly due to a decrease in SVI of 0.45 ml/m2 (95% CI 0.32 to 0.57 ml/m2) per year (P <0.0001). The mean CI of young healthy humans is approximately 3.5 l/min/m2 and declines by approximately 40 ml/min/m2 per year, mostly due to a decline in stroke volume (SV). These findings have significant implications regarding the clinical interpretation of haemodynamic parameters and the application of these results to individual patients.

scholarly journals Mechanisms contributing to hypotension after anesthetic induction with sufentanil, propofol, and rocuronium: a prospective observational study

2021 ◽  
Author(s):  
Bernd Saugel ◽  
Elisa-Johanna Bebert ◽  
Luisa Briesenick ◽  
Phillip Hoppe ◽  
Gillis Greiwe ◽  
...  
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Resistance Index ◽  
Stroke Volume Index ◽  
Volume Index ◽  
Systemic Vascular Resistance Index ◽  
Anesthetic Induction

AbstractIt remains unclear whether reduced myocardial contractility, venous dilation with decreased venous return, or arterial dilation with reduced systemic vascular resistance contribute most to hypotension after induction of general anesthesia. We sought to assess the relative contribution of various hemodynamic mechanisms to hypotension after induction of general anesthesia with sufentanil, propofol, and rocuronium. In this prospective observational study, we continuously recorded hemodynamic variables during anesthetic induction using a finger-cuff method in 92 non-cardiac surgery patients. After sufentanil administration, there was no clinically important change in arterial pressure, but heart rate increased from baseline by 11 (99.89% confidence interval: 7 to 16) bpm (P < 0.001). After administration of propofol, mean arterial pressure decreased by 23 (17 to 28) mmHg and systemic vascular resistance index decreased by 565 (419 to 712) dyn*s*cm−5*m2 (P values < 0.001). Mean arterial pressure was < 65 mmHg in 27 patients (29%). After propofol administration, heart rate returned to baseline, and stroke volume index and cardiac index remained stable. After tracheal intubation, there were no clinically important differences compared to baseline in heart rate, stroke volume index, and cardiac index, but arterial pressure and systemic vascular resistance index remained markedly decreased. Anesthetic induction with sufentanil, propofol, and rocuronium reduced arterial pressure and systemic vascular resistance index. Heart rate, stroke volume index, and cardiac index remained stable. Post-induction hypotension therefore appears to result from arterial dilation with reduced systemic vascular resistance rather than venous dilation or reduced myocardial contractility.

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