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.

Finger Arterial versus Intrabrachial Pressure and Continuous Cardiac output during Head-up Tilt Testing in Healthy Subjects

1996 ◽  
Vol 91 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Wilbert T. Jellema ◽  
Ben P. M. Imholz ◽  
Jeroen Van Goudoever ◽  
Karel H. Wesseling ◽  
Johannes J. Van Lieshout
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Healthy Subjects ◽  
Pulse Contour Analysis ◽  
Pulse Contour ◽  
Mean Blood Pressure ◽  
Contour Analysis ◽  
Head Up Tilt ◽  
The Difference

1. The aims of this study were to determine the clinical feasibility of continuous, non-invasive Finapres recordings as a replacement for intrabrachial pressure during a 30 min head-up tilt, and the reliability of continuous cardiac output computation by pulse contour analysis from the finger arterial versus the brachial waveform. 2. In eight healthy subjects a 30 min 70° passive head-up tilt was performed. Finger arterial (FINAP) and intrabrachial (IAP) pressures were measured simultaneously. Beat-to-beat changes in stroke volume were computed using a pulse contour algorithm. 3. Accuracy (the group-averaged FINAP—IAP difference) and precision (the SD of the difference) of Finapres measurements were 4 and 9 mmHg for systolic blood pressure, −5 and 9 mmHg for mean blood pressure and −5 and 9 mmHg for diastolic blood pressure. 4. The time course of the FINAP—IAP differences during head-up tilt showed a linear trend (P < 0.001 for all pressure levels). Averaged for the group, the difference increased 7 mmHg for mean blood pressure. The difference in stroke volume computed from FINAP and IAP was 0.3 ± 5% (mean ± SD), and independent of the duration of the tilt (P > 0.05). This difference did not change at low blood pressure levels (0.5 ± 6%). 5. The qualitative performance of the Finapres allows it to be used in the clinical setting as a monitor of sudden changes in blood pressure induced by a 30 min head-up tilt. Relative changes in stroke volume, as obtained by pulse contour analysis of the finger arterial waveform, closely follow intrabrachial values during long-duration head-up tilt and associated arterial hypotension.

scholarly journals Hemodynamic Changes Associated with Spinal Anesthesia for Cesarean Delivery in Severe Preeclampsia

2008 ◽  
Vol 108 (5) ◽  
pp. 802-811 ◽  
Author(s):  
Robert A. Dyer ◽  
Jenna L. Piercy ◽  
Anthony R. Reed ◽  
Carl J. Lombard ◽  
Leann K. Schoeman ◽  
...  
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Spinal Anesthesia ◽  
Cesarean Delivery ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Severe Preeclampsia

Background Hemodynamic responses to spinal anesthesia (SA) for cesarean delivery in patients with severe preeclampsia are poorly understood. This study used a beat-by-beat monitor of cardiac output (CO) to characterize the response to SA. The hypothesis was that CO would decrease from baseline values by less than 20%. Methods Fifteen patients with severe preeclampsia consented to an observational study. The monitor employed used pulse wave form analysis to estimate nominal stroke volume. Calibration was by lithium dilution. CO and systemic vascular resistance were derived from the measured stroke volume, heart rate, and mean arterial pressure. In addition, the hemodynamic effects of phenylephrine, the response to delivery and oxytocin, and hemodynamics during recovery from SA were recorded. Hemodynamic values were averaged for defined time intervals before, during, and after SA. Results Cardiac output remained stable from induction of SA until the time of request for analgesia. Mean arterial pressure and systemic vascular resistance decreased significantly from the time of adoption of the supine position until the end of surgery. After oxytocin administration, systemic vascular resistance decreased and heart rate and CO increased. Phenylephrine, 50 mug, increased mean arterial pressure to above target values and did not significantly change CO. At the time of recovery from SA, there were no clinically relevant changes from baseline hemodynamic values. Conclusions Spinal anesthesia in severe preeclampsia was associated with clinically insignificant changes in CO. Phenylephrine restored mean arterial pressure but did not increase maternal CO. Oxytocin caused transient marked hypotension, tachycardia, and increases in CO.

scholarly journals CK (Creatine Kinase) Is Associated With Cardiovascular Hemodynamics

Hypertension ◽  
2020 ◽  
Vol 76 (2) ◽  
pp. 373-380 ◽  
Author(s):  
Lizzy M. Brewster ◽  
Yentl C. Haan ◽  
Aeilko H. Zwinderman ◽  
Bert Jan van den Born ◽  
Gert A. van Montfrans
Keyword(s):  
Blood Pressure ◽  
Creatine Kinase ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
African Ancestry ◽  
Cardiac Contractility ◽  
Urban Setting ◽  
Cardiovascular Hemodynamics

The ATP-regenerating enzyme CK (creatine kinase) is strongly associated with blood pressure, which lowers upon experimental CK inhibition. The enzyme is thought to affect cardiovascular hemodynamics through enhanced systemic vascular resistance, stroke volume, and cardiac contractility, but data on these parameters are lacking. We hereby report hemodynamics by CK levels in the multiethnic, cross-sectional HELIUS study (Healthy Life in an Urban Setting). Physical examination included sitting brachial blood pressure and noninvasively assessed supine systemic vascular resistance, stroke volume, cardiac output, and cardiac contractility, which we associated with resting plasma CK. Data from 14 937 men and women (mean age, 43.3; SD, 12.9) indicated that per log CK increase, blood pressure increased with 20.2 (18.9–21.4) mm Hg systolic/13.0 (12.2–13.7) diastolic, an odds ratio for hypertension of 6.1 (5.1–7.2). Outcomes were similar by sex, body mass index, and ancestry, although higher blood pressures in men, with overweight/obesity, and West-African ancestry were partially explained by higher CK, with an adjusted increase in systolic/diastolic pressure of 10.5 (10.0–10.9)/6.4 (6.0–6.7) mm Hg per log CK increase. Systemic vascular resistance, stroke volume, cardiac output, and cardiac contractility (n=7876), increased by respectively 20%, 39%, 14%, and 23% SD per log CK increase. This study indicates that the association of CK with blood pressure likely results from an increase in systemic vascular resistance and stroke volume. These data expand the knowledge on the nature of hypertension associated with CK and may inform further experiments on CK inhibition as a means to lower blood pressure.

Effects of Leg Muscle Pumping and Tensing on Orthostatic Arterial Pressure: A Study in Normal Subjects and Patients with Autonomic Failure

1994 ◽  
Vol 87 (5) ◽  
pp. 553-558 ◽  
Author(s):  
A. D. J. Ten Harkel ◽  
J. J. Van Lieshout ◽  
W. Wieling
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Healthy Subjects ◽  
Healthy Adult ◽  
Autonomic Failure ◽  
Contour Method ◽  
Orthostatic Blood Pressure ◽  
Leg Muscle

1. The effects of leg muscle pumping (tiptoeing) and tensing (leg-crossing) on orthostatic blood pressure were investigated in six healthy adult subjects (aged 28–34 years) and in seven patients with severe hypoadrenergic orthostatic hypotension (aged 20–65 years). 2. Finger arterial pressure was monitored. Relative changes in left ventricular stroke volume were computed by a pulse contour method. 3. Tiptoeing increased mean arterial pressure (7 ± 5 mmHg) in the healthy subjects, but not in the patients, whereas cardiac output increased in both groups, although by more in the healthy adults than in the patients (35 ± 10% versus 20 ± 11%, P < 0.05). Systemic vascular resistance decreased substantially in both groups while tiptoeing. Leg-crossing did not affect arterial pressure in the healthy subjects, although stroke volume had increased. In contrast, in the patients an increase in cardiac output (16 ± 12%) and mean blood pressure (13 ± 13 mmHg) was observed. 4. Tiptoeing and leg-crossing have different effects on orthostatic blood pressure in healthy adult subjects and in patients with autonomic failure. In normal humans, tiptoeing increases arterial pressure, whereas leg-crossing has little effect. In the patients, in contrast, tiptoeing has little effect, whereas leg-crossing increases arterial pressure considerably. Patients with autonomic failure should be instructed to apply leg-crossing to combat orthostatic dizziness.

scholarly journals Effects of vagotomy on cardiovascular response to periodic apneas in sedated pigs

1999 ◽  
Vol 86 (6) ◽  
pp. 1890-1896 ◽  
Author(s):  
D. Slamowitz ◽  
L. Chen ◽  
S. M. Scharf
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Cardiovascular Response ◽  
Pressor Response ◽  
Mechanical Effects

There are few studies investigating the influence of vagally mediated reflexes on the cardiovascular response to apneas. In 12 sedated preinstrumented pigs, we studied the effects of vagotomy during apneas, controlling for apnea periodicity and thoracic mechanical effects. Nonobstructive apneas were produced by paralyzing and mechanically ventilating the animals, then turning the ventilator off and on every 30 s. Before vagotomy, relative to baseline, apnea caused increased mean arterial pressure (MAP; +19 ± 25%, P < 0.05), systemic vascular resistance (SVR; +33 ± 16%, P < 0.0005), and heart rate (HR; +5 ± 6%, P < 0.05) and decreased cardiac output (CO) and stroke volume (SV; −16 ± 10% P < 0.001). After vagotomy, no significant change occurred in MAP, SVR, and SV during apneas, but CO and HR increased relative to baseline. HR was always greater (∼14%, P < 0.01) during the interapneic interval compared with during apnea. We conclude that vagally mediated reflexes are important mediators of the apneic pressor response. HR increases after apnea termination are related, at least in part, to nonvagally mediated reflexes.

scholarly journals Haemodynamic Characteristics And Factors Influencing The Head-Up Tilt Test In Patients With Orthostatic Hypotension

2021 ◽  
Author(s):  
Wang Jiayu ◽  
Wu Yueyang ◽  
Wang Yongjun ◽  
Zhao Xingquan ◽  
Wang Yilong ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Stroke Volume ◽  
Systolic Blood Pressure ◽  
Orthostatic Hypotension ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Tilt Test ◽  
Head Up Tilt ◽  
Head Up Tilt Test

Abstract Background: Failure to activate autonomic neural and hormonal reflex mechanisms could result in orthostatic hypotension. Patients with orthostatic hypotension often experience symptoms of cerebral hypoperfusion, including syncope. The purpose of this study was to investigate the haemodynamic characteristics of patients with orthostatic hypotension and the factors affecting blood pressure regulation.Methods: This retrospective study enrolled 45 patients who were diagnosed with typical orthostatic hypotension by the head-up tilt test at Beijing Tiantan Hospital, Capital Medical University from June 2019 to December 2020. Changes in haemodynamic parameters in these patients were compared in the supine and tilted upright positions.Results: For all patients, haemodynamic parameters in the supine and tilted upright positions were compared, and systolic blood pressure, diastolic blood pressure, mean blood pressure, cardiac output and stroke volume were all significantly decreased per minute. Heart rate significantly increased per minute, but systemic vascular resistance did not significantly change. The absolute value, percentage and rate of increases in heart rate and the absolute value, percentage and rate of decreases in stroke volume from the supine to the titled upright position were significantly lower in patients 60 years and older than in patients under 60 years old. Linear regression analyses found that the changes in heart rate, stroke volume and systemic vascular resistance were related to changes in systolic blood pressure, while the changes in stroke volume and systemic vascular resistance had more important effects on systolic blood pressure.Conclusions: In patients with orthostatic hypotension, we observed no significant increase in systemic vascular resistance from the supine position to the tilted upright position. Nevertheless, an increase in systemic vascular resistance had a significant impact on the maintenance of systolic blood pressure. In addition, in orthostatic hypotension patients younger than 60 years of age, heart rate increased while stroke volume decreased significantly after tilting upright compared with orthostatic hypotension patients older than 60 years of age and older.

scholarly journals Hemodynamic abnormalities during muscle metaboreflex activation in patients with type 2 diabetes mellitus

2019 ◽  
Vol 126 (2) ◽  
pp. 444-453 ◽  
Author(s):  
Silvana Roberto ◽  
Raffaele Milia ◽  
Azzurra Doneddu ◽  
Virginia Pinna ◽  
Girolamo Palazzolo ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Blood Pressure ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Cardiac Output ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Blood Pressure Response ◽  
Pressure Response

Metaboreflex is a reflex triggered during exercise or postexercise muscle ischemia (PEMI) by metaboreceptor stimulation. Typical features of metaboreflex are increased cardiac output (CO) and blood pressure. Patients suffering from metabolic syndrome display hemodynamic abnormalities, with an exaggerated systemic vascular resistance (SVR) and reduced CO response during PEMI-induced metaboreflex. Whether patients with type 2 diabetes mellitus (DM2) have similar hemodynamic abnormalities is unknown. Here we contrast the hemodynamic response to PEMI in 14 patients suffering from DM2 (age 62.7 ± 8.3 yr) and in 15 age-matched controls (CTLs). All participants underwent a control exercise recovery reference test and a PEMI test to obtain the metaboreflex response. Central hemodynamics were evaluated by unbiased operator-independent impedance cardiography. Although the blood pressure response to PEMI was not significantly different between the groups, we found that the SVR and CO responses were reversed in patients with DM2 as compared with the CTLs (SVR: 392.5 ± 549.6 and −14.8 ± 258.9 dyn·s−1·cm−5; CO: −0.25 ± 0.63 and 0.46 ± 0.50 l/m, respectively, in DM2 and in CTL groups, respectively; P < 0.05 for both). Of note, stroke volume (SV) increased during PEMI in the CTL group only. Failure to increase SV and CO was the consequence of reduced venous return, impaired cardiac performance, and augmented afterload in patients with DM2. We conclude that patients with DM2 have an exaggerated vasoconstriction in response to metaboreflex activation not accompanied by a concomitant increase in heart performance. Therefore, in these patients, blood pressure response to the metaboreflex relies more on SVR increases rather than on increases in SV and CO. NEW & NOTEWORTHY The main new finding of the present investigation is that subjects with type 2 diabetes mellitus have an exaggerated vasoconstriction in response to metaboreflex activation. In these patients, blood pressure response to the metaboreflex relies more on systemic vascular resistance than on cardiac output increments.

The effect of Trendelenburg and modified trendelenburg positions on cardiac output, blood pressure, and oxygenation: a preliminary study

1994 ◽  
Vol 3 (5) ◽  
pp. 382-386 ◽  
Author(s):  
CL Ostrow ◽  
E Hupp ◽  
D Topjian
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Critically Ill ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Critically Ill Patients ◽  
Hemodynamic Parameters ◽  
Trendelenburg Position ◽  
Dependent Variables ◽  
Preliminary Study

BACKGROUND: Although we have insufficient knowledge about the effects of Trendelenburg positions on various hemodynamic parameters, these positions are frequently used to influence cardiac output and blood pressure in critically ill patients. OBJECTIVES: To determine the effect of Trendelenburg and modified Trendelenburg positions on five dependent variables: cardiac output, cardiac index, mean arterial pressure, systemic vascular resistance, and oxygenation in critically ill patients. METHODS: In this preliminary study subjects were 23 cardiac surgery patients (mean age, 55; SD, 8.09) who had a pulmonary artery catheter for cardiac output determination and who were clinically stable, normovolemic and normotensive. Baseline measurements of the dependent variables were taken in the supine position. Patients were then placed in 10 degrees Trendelenburg or 30 degrees modified Trendelenburg position. The dependent variables were measured after 10 minutes in each position. A 2-period, 2-treatment crossover design with a preliminary baseline measurement was used. RESULTS: Five subjects were unable to tolerate Trendelenburg position because of nausea or pain in the sternal incision. In the 18 who were able to tolerate both position changes, no statistically significant changes were found in the five dependent variables. Changes in systemic vascular resistance over time approached statistical significance and warrant further study. CONCLUSIONS: This preliminary study does not provide support for Trendelenburg positions as a means to influence hemodynamic parameters such as cardiac output and blood pressure in normovolemic and normotensive patients.

L-propionylcarnitine increases postischemic blood flow but does not affect recovery of energy charge

1991 ◽  
Vol 261 (1) ◽  
pp. H172-H180 ◽  
Author(s):  
L. M. Sassen ◽  
K. Bezstarosti ◽  
W. J. Van der Giessen ◽  
J. M. Lamers ◽  
P. D. Verdouw
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Systemic Vascular Resistance ◽  
Arterial Blood Pressure ◽  
Vascular Resistance ◽  
Contractile Function ◽  
Energy Charge ◽  
Left Ventricular ◽  
Arterial Blood

Effects of pretreatment with L-propionylcarnitine (50 mg/kg, n = 9) or saline (n = 10) were studied in open-chest anesthetized pigs, in which ischemia was induced by decreasing left anterior descending coronary artery blood flow to 20% of baseline. After 60 min of ischemia, myocardium was reperfused for 2 h. In both groups, flow reduction abolished contractile function of the affected myocardium and caused similar decreases in ATP (by 55%) and energy charge [(ATP + 0.5ADP)/(ATP + ADP + AMP); decrease from 0.91 to 0.60], mean arterial blood pressure (by 10-24%), the maximum rate of rise in left ventricular pressure (by 26-32%), and cardiac output (by 20-30%). During reperfusion, “no-reflow” was attenuated by L-propionylcarnitine, because myocardial blood flow returned to 61 and 82% of baseline in the saline- and L-propionylcarnitine-treated animals, respectively. Cardiac output of the saline-treated animals further decreased (to 52% of baseline), and systemic vascular resistance increased from 46 +/- 3 to 61 +/- 9 mmHg.min.l-1, thereby maintaining arterial blood pressure. In L-propionylcarnitine-treated pigs, cardiac output remained at 75% of baseline, and systemic vascular resistance decreased from 42 +/- 3 to 38 +/- 4 mmHg.min.l-1. In both groups, energy charge but not the ATP level of the ischemic-reperfused myocardium tended to recover, whereas the creatine phosphate level showed significantly more recovery in saline-treated animals. We conclude that L-propionylcarnitine partially preserved vascular patency in ischemic-reperfused porcine myocardium but had no immediate effect on “myocardial stunning.” Potential markers for long-term recovery were not affected by L-propionylcarnitine.

Rho kinase and Ca2+ entry mediate increased pulmonary and systemic vascular resistance in l-NAME-treated rats

2007 ◽  
Vol 293 (5) ◽  
pp. L1306-L1313 ◽  
Author(s):  
Jasdeep S. Dhaliwal ◽  
David B. Casey ◽  
Anthony J. Greco ◽  
Adeleke M. Badejo ◽  
Thomas B. Gallen ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Pulmonary Arterial Pressure ◽  
Rho Kinase ◽  
Systemic Arterial Pressure ◽  
Intravenous Injections ◽  
Pulmonary Arterial ◽  
Dose Dependent

The small GTP-binding protein and its downstream effector Rho kinase play an important role in the regulation of vasoconstrictor tone. Rho kinase activation maintains increased pulmonary vascular tone and mediates the vasoconstrictor response to nitric oxide (NO) synthesis inhibition in chronically hypoxic rats and in the ovine fetal lung. However, the role of Rho kinase in mediating pulmonary vasoconstriction after NO synthesis inhibition has not been examined in the intact rat. To address this question, cardiovascular responses to the Rho kinase inhibitor fasudil were studied at baseline and after administration of an NO synthesis inhibitor. In the intact rat, intravenous injections of fasudil cause dose-dependent decreases in systemic arterial pressure, small decreases in pulmonary arterial pressure, and increases in cardiac output. l-NAME caused a significant increase in pulmonary and systemic arterial pressures and a decrease in cardiac output. The intravenous injections of fasudil after l-NAME caused dose-dependent decreases in pulmonary and systemic arterial pressure and increases in cardiac output, and the percent decreases in pulmonary arterial pressure in response to the lower doses of fasudil were greater than decreases in systemic arterial pressure. The Ca++ entry blocker isradipine also decreased pulmonary and systemic arterial pressure in l-NAME-treated rats. Infusion of sodium nitroprusside restored pulmonary arterial pressure to baseline values after administration of l-NAME. These data provide evidence in support of the hypothesis that increases in pulmonary and systemic vascular resistance following l-NAME treatment are mediated by Rho kinase and Ca++ entry through L-type channels, and that responses to l-NAME can be reversed by an NO donor.

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