Central Haemodynamic Effects Research Articles

Cardiopulmonary haemodynamic effects and gas exchange during apnoeic oxygenation with high-flow and low-flow nasal oxygen: A large animal study.

Apnoeic oxygenation with high-flow nasal oxygen prolongs the safe apnoeic period during induction of general anaesthesia. However, central haemodynamic effects and the characteristics of central gaseous exchange remain unexplored. To describe mean pulmonary arterial pressure along with arterial and mixed venous blood gases and central haemodynamic parameters during apnoeic oxygenation with low-flow and high-flow nasal oxygen in pigs. Experimental crossover study. Animal study of 10 healthy Swedish landrace pigs at Karolinska Institutet, Sweden, April-May 2021. The pigs were anaesthetised, their tracheas intubated and their pulmonary arteries catheterised. The animals were preoxygenated and paralysed before apnoea. Apnoeic periods between 45 and 60 min were implemented with either 70 or 10 l min -1 100% O 2 delivered via nasal catheters. In addition, seven animals underwent an apnoea without fresh gas flow. Cardiopulmonary parameters and blood gases were measured repeatedly. Mean pulmonary arterial pressure during apnoeic oxygenation with high-flow and low-flow oxygen. Nine pigs completed two apnoeic periods of at least 45 min with a Pa O 2 not lower than 13 kPa. The mean pulmonary arterial pressure increased during 45 min of apnoea, from 18 ± 1 to 33 ± 2 mmHg and 18 ± 1 to 35 ± 2 mmHg, at 70 and 10 l min -1 O 2 , respectively ( P < 0.001); there was no difference between the groups ( P = 0.87). The Pa CO 2 increased by 0.48 ± 0.07 and 0.52 ± 0.04 kPa min -1 , at 70 and 10 l min -1 O 2 , respectively; there was no difference between the groups ( P = 0.22). During apnoea without fresh gas flow, the SpO 2 declined to less than 85% after 155 ± 11 s. During apnoeic oxygenation in pigs, the mean pulmonary arterial pressure increased two-fold and Pa CO 2 five-fold after 45 min, while the arterial oxygen levels were maintained over 13 kPa, irrespective of high-flow or low-flow oxygen.

Cardiac and renal effects of a transjugular intrahepatic portosystemic shunt in cirrhosis

Refractory ascites and recurrent variceal bleeding are among the serious complications of portal hypertension and cirrhosis for which a transjugular intrahepatic portosystemic shunt (TIPS) can be used. Cirrhotic patients have varying degrees of haemodynamic derangement, mainly characterized by peripheral arterial vasodilatation, central underfilling and activation of several vasoactive systems. These changes affect the heart, the lungs and the kidneys in particular. The cardiac effects of TIPS are immediate and are related to the redirection of blood from the splanchnic circulation into the systemic circulation, resulting in worsening of the hyperdynamic circulation with increasing cardiac output and decreasing systemic vascular resistance; further, TIPS may unmask a latent diastolic dysfunction of the heart. However, the renal effects of TIPS seem to be beneficial as renal function tends to improve in patients with the hepatorenal syndrome. The clinical and haemodynamic effects of TIPS have been studied intensively and will be reviewed in the present paper. Considerable knowledge on the effects of TIPS on the pathophysiology of cirrhosis has been gained, but studies on the central haemodynamic effects are warranted to refine the already applied treatments and develop new treatment modalities.

A prospective, randomized, open-label, active-controlled, clinical trial to assess central haemodynamic effects of bisoprolol and atenolol in hypertensive patients

The results from the ASCOT CAFÉ study demonstrated the inferiority of beta blockers in reducing central aortic blood pressure. In this study, we wanted to demonstrate whether or not second-generation beta blockers with higher beta 1 selectivity, namely bisoprolol, may counterbalance the effect of bradycardia through reduced reflection wave magnitude resulting from the relative lack of increase in peripheral vascular resistance. This was a prospective, randomized, open-label, active-controlled trial in 209 hypertensive patients to evaluate the effect of bisoprolol and atenolol on aortic pulse pressure. Patients received a once-daily 5 mg dose of bisoprolol (n = 96) or 50 mg dose of atenolol (n = 95) at baseline with titration up to bisprolol 10 mg and atenolol 100 mg allowed at the 4th week when the brachial blood pressure was above treatment goal (average dose: bisoprolol: 5.4 mg, atenolol: 52.8 mg). Central blood pressure and augmentation index were measured at baseline and 12 weeks later, by pulse wave analysis with radial artery tonometry. The primary endpoint of the study was the difference in the central pulse pressure (CPP) at 12 weeks. The results showed a significant reduction of CPP in both groups at week 12 of administration compared with the predose level (P < 0.05); however, there was no significant difference in terms of CPP change [bisoprolol (baseline CPP 47.49 ± 11.33, follow-up 43.09 ± 11.67) vs. atenolol (baseline CPP 45.93 ± 11.62, follow-up 42.23 ± 9.92), P = 0.594]. In this study, there was no significant difference between bisoprolol and atenolol in terms of reduction of aortic pulse pressure after 12 weeks of treatment.

Different patterns of peripheral versus central blood pressure in hypertensive patients treated with β-blockers either with or without vasodilator properties or with angiotensin receptor blockers

It is unclear whether the assumed inferiority of atenolol to reduce central (aortic) blood pressure (BP) extends to other β-blockers with vasodilating properties and, within that scope, how these drugs differ from the angiotensin receptor blockers (ARBs). In a retrospective study, we compared three groups of hypertensive patients (aged 35-65 years) chronically treated with either ARBs (n=83, group 1), carvedilol/nebivolol (n=75, 25+25 mg/day/5 mg/day, group 2) or atenolol (n=84, 50-100 mg/day, group 3), matched for age (mean 52 years), sex (61% female), brachial BP and concomitant use of diuretics (75-81%)and dihydropyridine calcium antagonists (27-33%). We measured aortic stiffness by pulse wave velocity (Complior), and central BP, central-peripheral pulse pressure amplification, wave reflection [augmentation index (AIx) corrected for heart rate] and augmentation pressure (Sphygmocor). For similar age, sex distribution, brachial BP levels (145/85±11/10 mmHg) and pulse wave velocity (10±2 m/s), the atenolol group showed significantly (P<0.03 analysis of variance) higher central systolic BP (139±9 mmHg) versus group 2 (135±10 mmHg) and group 1 (132±11 mmHg), higher AIx (34±12%) versus group 2 (27±7%) and group 1 (23.0±9%), lower pulse pressure amplification (1.16±0.09) versus group 2 (1.22±0.10) and group 1 (1.31±0.11) and lower heart rate beats/min (61±9) versus group 2 (69±11) and group 1 (82±11). The differences on these values, between group 2 and group 1, were also significant (P<0.04). After adjustment for the heart rate, AIx became similar in groups 2 and 1, but still lower (P<0.04) than the atenolol group. These findings suggest that, for similar brachial BP and aortic stiffness, treatment with either vasodilating β-blockers or angiotensin receptor blockers associates with lower central systolic BP and wave reflections than treatment with atenolol. These findings may suggest that the vasodilating β-blockers may exert more favourable central haemodynamic effects, compared with atenolol, which are more alike, although not completely equal, to those of the ARBs.

Acute central haemodynamic effects induced by intraperitoneal glucose instillation

The supposed lack of a haemodynamic impact of peritoneal dialysis (PD) has been challenged recently by the finding of a mild increase of peripheral blood pressure (BP) during an acute dwell. It is not clear whether, besides the effect of changes in intraperitoneal (IP) volume and/or pressure, IP glucose instillation and absorption plays a role in this. Therefore, we tested the impact of IP instillation of glucose on the evolution of central haemodynamic parameters, using SphygmoCor, during an acute dwell with two different glucose concentrations. Stable, non-diabetic PD patients (N = 22) were treated consecutively in a randomized, cross-over design (A then B or B then A) with one 1.36% (A) and one 3.86% (B) physioneal dwell of 100 min. Central BP was measured with SphygmoCor and blood was sampled for serum glucose and insulin levels every 20 min. Insulin resistance was defined as a Homeostatic Model Assessment Index (HOMA-index) >1.4. Serum glucose levels rose during both the 1.36% and the 3.86% dwell, whereas insulin levels rose only during the 3.86% dwell. The increase of both glucose and insulin levels was more pronounced in patients with insulin resistance (11/22 patients). There was, however, no accompanying change versus baseline in haemodynamic parameters (carotid systolic blood pressure, diastolic BP, heart rate or augmentation index). Despite substantial increases in blood glucose and insulin levels, there was no accompanying change in central haemodynamic parameters during an acute PD dwell with low or high glucose concentrations.

Leg crossing with muscle tensing, a physical counter-manoeuvre to prevent syncope, enhances leg blood flow

In patients with orthostatic intolerance, the mechanisms to maintain BP (blood pressure) fail. A physical counter-manoeuvre to postpone or even prevent orthostatic intolerance in these patients is leg crossing combined with muscle tensing. Although the central haemodynamic effects of physical counter-manoeuvres are well documented, not much is known about the peripheral haemodynamic events. Therefore the purpose of the present study was to examine the peripheral haemodynamic effects of leg crossing combined with muscle tensing during 70 degrees head-up tilt. Healthy subjects (n=13) were monitored for 10 min in the supine position followed by 10 min in 70 degrees head-up tilt and, finally, for 2 min of leg crossing with muscle tensing in 70 degrees head-up tilt. MAP (mean arterial BP), heart rate, stroke volume, cardiac output and total peripheral resistance were measured continuously by Portapres. Leg blood flow was measured using Doppler ultrasound. Leg vascular conductance was calculated as leg blood flow/MAP. A significant increase in MAP (13 mmHg), stroke volume (27%) and cardiac output (18%), a significant decrease in heart rate (-5 beats/min) and no change in total peripheral resistance during the physical counter-manoeuvre were observed when compared with baseline 70 degrees head-up tilt. A significant increase in leg blood flow (325 ml/min) and leg vascular conductance (2.9 arbitrary units) were seen during the physical counter-manoeuvre when compared with baseline 70 degrees head-up tilt. In conclusion, the present study indicates that the physical counter-manoeuvre of leg crossing combined with muscle tensing clearly enhances leg blood flow and, at the same time, elevates MAP.

Randomized trials are also essential for device therapy: reply

Randomized trials are also essential for device therapy: reply

Central and peripheral haemodynamic effects of hyperglycaemia, hyperinsulinaemia, hyperlipidaemia or a mixed meal.

The aim of the present study was to evaluate the haemodynamic changes during hyperinsulinaemia, hyperglycaemia or hypertriglyceridaemia in relation to those following a mixed meal. Ten subjects were subjected to hypertriglyceridaemia (3.9 mmol/l) for 2 h by an infusion of Intralipid and heparin. Nine subjects received a hyperglycaemic clamp (12.5 mmol/l) with octreotide and low-dose insulin infusion to maintain normoinsulinaemia (10 m-units/l). Ten subjects received saline for 2 h as a control and, thereafter, 2 h of normoglycaemic hyperinsulinaemic clamp (80 m-units/l). Finally, ten subjects were evaluated for 2 h following an ordinary mixed meal. Calf blood flow was measured by venous occlusion plethysmography and cardiac index by thoracic bioimpedance. Both the mixed meal and normoglycaemic hyperinsulinaemia lowered total peripheral resistance, and increased calf blood flow and cardiac index, whereas blood pressure decreased (P <0.05-0.001). Both hyperglycaemia and hypertriglyceridaemia increased calf blood flow, but blood pressure was unchanged. Total peripheral resistance was unchanged in hypertriglyceridaemia, whereas hyperglycaemia induced a significant increase. Normoglycaemic hyperinsulinaemia induced a haemodynamic pattern similar, but to a lesser extent, to the pattern seen following a mixed meal. Hyperinsulinaemia seems to be a major mediator of the haemodynamic response, but other factors are obviously also of great importance. Hypertriglyceridaemia and hyperglycaemia induced haemodynamic responses that are not similar to those seen following a mixed meal.

Cardiovascular effects and cardiopulmonary plasma gradients following intravenous infusion of neuropeptide Y in humans: negative dromotropic effect on atrioventricular node conduction.

Neuropeptide Y (NPY) is co-released with noradrenaline from sympathetic nerves, has a strong vasoconstrictive action, and causes an attenuation of parasympathetic action in animal experiments. The plasma level of NPY is greatly elevated in patients with congestive heart failure, but the clinical relevance of this finding is unclear. Central haemodynamic effects, cardiac conduction system electrophysiology and coronary sinus blood flow were therefore studied in two sets of experiments, each carried out on seven healthy men. In the first series, NPY was given intravenously at doses of 3, 10 and 30 pmol.min(-1).kg(-1), and in the second it was given as a bolus injection of 90, 200 or 900 pmol/kg, which resulted in plasma concentrations similar to those seen in heart failure patients. During continuous infusion of NPY, systemic blood pressure increased slightly, but myocardial perfusion, cardiac output, pulmonary arterial pressure, cardiac conduction intervals and atrioventricular (AV) node functional measures remained unchanged. In contrast, the bolus injection of NPY evoked prolongation and block (in four out of seven subjects) of AV node conduction, but did not affect haemodynamic variables, apart from a minor increase in systemic blood pressure. Impaired AV node conduction is a novel observation, which might reflect a baroreceptor-mediated vagal reflex, or - more likely - an NPY-induced direct negative dromotropic effect, caused by a reduction of the L-type calcium current as observed in vitro, or a combination of the two.

Beneficial haemodynamic effects of insulin in chronic heart failure

OBJECTIVETo characterise the central and regional haemodynamic effects of insulin in patients with chronic heart failure.DESIGNSingle blind, placebo controlled study.SETTINGUniversity teaching hospital.PATIENTSTen patients with stable chronic heart failure.INTERVENTIONSHyperinsulinaemic euglycaemic clamp and non-invasive haemodynamic measurements.MAIN OUTCOME MEASURESChange in resting heart rate, blood pressure, cardiac output, and regional splanchnic and skeletal muscle blood flow.RESULTSInsulin infusion led to a dose dependent increase in skeletal muscle blood flow of 0.36 (0.13) and 0.73 (0.14) ml/dl/min during low and high dose insulin infusions (p &lt; 0.05 and p &lt; 0.005 v placebo, respectively). Low and high dose insulin infusions led to a fall in heart rate of 4.6 (1.4) and 5.1 (1.3) beats/min (p &lt; 0.05 and p &lt; 0.005 v placebo, respectively) and a modest increase in cardiac output. There was no significant change in superior mesenteric artery blood flow.CONCLUSIONIn patients with chronic heart failure insulin is a selective skeletal muscle vasodilator that leads to increased muscle perfusion primarily through redistribution of regional blood flow rather than by increased cardiac output. These results provide a rational haemodynamic explanation for the apparent beneficial effects of insulin infusion in the setting of heart failure.

Central and systemic haemodynamic effects of terlipressin in portal hypertensive patients

Cirrhotic patients exhibit a hyperdynamic and hyporeactive circulation with central hypovolaemia which may influence the course of the disease. As terlipressin, a vasopressin analogue, may modify systemic haemodynamics in these patients, the aim of the present study was to assess the acute effects of terlipressin on central and systemic haemodynamics. Sixteen patients with alcoholic cirrhosis and portal hypertension had their systemic, central, and splanchnic haemodynamics determined at baseline and after a blind randomised bolus infusion (2 mg) of terlipressin/placebo. After terlipressin, the arterial blood pressure and the systemic vascular resistance increased by 26% and 61%, respectively (both p<0.001), and the cardiac output, heart rate, and arterial compliance decreased by 18%, 11%, and 32%, respectively (all p<0.001). The central circulation time increased by 36% (p<0.001), whereas the central and arterial blood volume only increased by 4% (p= 0.07). As expected, both portal pressure and hepatic blood flow decreased (17% and 29%, both p<0.001). The decrease in portal pressure after terlipressin was significantly related to the increase in systemic vascular resistance (r=-0.52, p<0.05) and the central circulation time (r=-0.80, p<0.0001). Terlipressin significantly attenuates the hyperdynamic circulation in portal hypertensive patients without a further contraction of the central and arterial blood volume. The systemic haemodynamic response to terlipressin is moreover associated with the decrease in portal pressure. Terlipressin may therefore have potentially beneficial effects on the hyperdynamic circulation in cirrhosis in addition to its effects on portal pressure.

Clinical features of an anti-anginal drug in angina pectoris.

Trimetazidine (TMZ) exerts anti-ischaemic effects without any associated central haemodynamic change, both at rest and with exercise. These findings suggest that TMZ has a direct cytoprotective effect, the efficacy of which has been confirmed by clinical studies in effort angina. TMZ as monotherapy when compared with placebo, in acute (60 mg) as well as in chronic (20 mg t.i.d.) administration, significantly improves exercise tolerance: total work, duration of exercise and time to 1 mm ST segment depression, without changing the rate-pressure product. Moreover, during chronic treatment TMZ decreases the rate of anginal attacks. In patients with coronary heart disease insufficiently controlled with nifedipine or a beta-blocker as monotherapy, the addition of TMZ (20 mg t.i.d.) significantly reduces the number of anginal attacks and improves exercise capacity. TMZ antianginal activity in monotherapy has also been compared in double-blind controlled studies with that of a calcium channel antagonist and a beta-blocker as reference drugs. TMZ is as efficient as nifedipine or propranolol on clinical variables as well as on ergometric criteria, but unlike these two reference drugs, which act through a haemodynamic mechanism, TMZ does not decrease rate-pressure product. Furthermore, in the study comparing TMZ with propranolol, TMZ was shown to decrease ischaemic episodes recorded by ECG ambulatory monitoring. These data show that TMZ belongs to the major antianginal agents available today. However, the absence of central haemodynamic effects suggests that the drug has a novel anti-ischaemic mechanism involving direct myocardial cytoprotection.

Food in chronic heart failure: improvement in central haemodynamics but deleterious effects on exercise tolerance

Food has been known to have significant central haemodynamic effects for over half a century; it causes an increase in cardiac output and a fall in systemic vascular resistance. These changes are potentially desirable in patients with chronic heart failure but how they relate to exercise tolerance is unknown. This study was designed to examine the haemodynamic effects of food with changes in exercise capability in a group of patients with chronic heart failure. Fifteen patients with chronic heart failure and 10 normal control subjects were studied. They underwent treadmill exercise testing whilst fasting and after a standardized meal. Measurements were made of symptom-limited exercise tolerance, cardiac output, limb blood flow and respiratory gases. Superior mesenteric artery blood flow was measured fasting and postprandially only. Despite an increase in cardiac output, at rest and during exercise, which was not, however, as great as that in the control subjects, the symptom-limited exercise tolerance of the patients fell by 37 s postprandially (P < 0.05). Superior mesenteric artery blood flow increased postprandially by a mean of 133 ml.min-1 (P < 0.05) in the patients and 424 ml.min-1 (P < 0.01) in the control subjects. Calf blood flow increased in both groups during exercise, but there was no change in limb blood flow when comparisons were made between the fasting and postprandial states. The normal postprandial increase in oxygen consumption did not occur in the patients although their minute ventilation was higher than the control subjects (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The central haemodynamic effects of a single intravenous dose of flosequinan in patients with severe heart failure

The acute central haemodynamic and neuroendocrine effects of intravenous flosequinan were studied in a group of 10 patients with severe heart failure. Flosequinan improved cardiac output by a maximum of 1.59 l.min-1, it reduced pulmonary capillary wedge pressure by 11.9 mm Hg and it also caused a reduction in right atrial pressure by a maximum of 7.2 mm Hg. It tended to cause a fall in plasma adrenaline levels but not in plasma noradrenaline. There was little fall in blood pressure in response to flosequinan and no patient developed an adverse event. Intravenous flosequinan may be a useful candidate drug for controlled clinical studies in patients with severe heart failure.

Systemic, Pulmonary and Renal Haemodynamic Effects of Intravenously Infused Iopentol

The central, peripheral and renal haemodynamic effects after intravenous infusion (1 ml/s) of high doses (4 mg I/kg) of two low osmolar, chemically and physically similar non-ionic contrast media (iohexol and iopentol) were investigated in 16 pigs. Both contrast media induced a significant increase of mean arterial, mean right atrial, mean pulmonary arterial and mean pulmonary arterial occlusion pressure along with an increase in cardiac output. The systemic vascular and pulmonary vascular resistances were decreased. Renal venous blood flow and renal vascular resistance were not significantly changed after infusion of contrast media. There were no differences in haemodynamic effects between the two media studied.

Systemic, pulmonary and renal haemodynamic effects of large intravenous doses of high and low osmolar contrast media

The central, peripheral and renal haemodynamic effects of intravenous infusion (1 ml/s) of large doses (4 ml/kg body weight) of non-ionic (iohexol) and ionic (metrizoate and ioxaglate) contrast media were studied in 24 anaesthetized pigs. All contrast media showed marked haemodynamic effects with an increase of mean right atrial pressure, mean pulmonary arterial pressure, mean pulmonary occlusion pressure, cardiac output and stroke volume. the response of the pulmonary circulation to contrast media was a fall rather than a rise in pulmonary vascular resistance. No significant changes were detected in the renal circulation after infusion of contrast media

Systemic, Pulmonary and Renal Haemodynamic Effects of Large Intravenous Doses of High and Low Osmolar Contrast Media; An Investigation in the Pig of Ratio 1.5 and Ratio 3 Media

The central, peripheral and renal haemodynamic effects of intravenous infusion (1 ml/s) of large doses (4 ml/kg body weight) of non-ionic (iohexol) and ionic (metrizoate and ioxaglate) contrast media were studied in 24 anaesthetized pigs. All contrast media showed marked haemodynamic effects with an increase of mean right atrial pressure, mean pulmonary arterial pressure, mean pulmonary occlusion pressure, cardiac output and stroke volume. The response of the pulmonary circulation to contrast media was a fall rather than a rise in pulmonary vascular resistance. No significant changes were detected in the renal circulation after infusion of contrast media.

Effects of food on the central and peripheral haemodynamic response to upright exercise in normal volunteers.

The central and peripheral haemodynamic effects of a modest meal were investigated in healthy volunteers at rest and in response to submaximal exercise. The meal increased heart rate, cardiac output, oxygen consumption, carbon dioxide production, and minute ventilation at rest and during exercise. The effects of food were additive to those induced by the exercise. Food had no effect on limb blood flow and lowered total systemic vascular resistance suggesting that there were no compensatory changes in regional blood flow to help redirect blood to the gut. An increase in cardiac output, and therefore myocardial work, is the predominant cardiovascular response to eating and this may help explain the postprandial deterioration in symptoms of some patients with cardiovascular disorders.

Systemic, pulmonary and renal haemodynamic effects of large intravenous doses of high and low osmolar contrast media

The central, peripheral and renal haemodynamic effects of intravenous infusion (1 ml/s) of large doses (4 ml/kg body weight) of non-ionic (iohexol) and ionic (metrizoate and ioxaglate) contrast media were studied in 24 anaesthetized pigs. All contrast media showed marked haemodynamic effects with an increase of mean right atrial pressure, mean pulmonary arterial pressure, mean pulmonary occlusion pressure, cardiac output and stroke volume. The response of the pulmonary circulation to contrast media was a fall rather than a rise in pulmonary vascular resistance. No significant changes were detected in the renal circulation after infusion of contrast media.

Systemic, pulmonary and renal haemodynamic effects of intravenously infused iopentol

The central, peripheral and renal haemodynamic effects after intravenous infusion (1 ml/s) of high doses (4 mg I/kg) of two low osmolar, chemically and physically similar non-ionic contrast media (iohexol and iopentol) were investigated in 16 pigs. Both contrast media induced a significant increase of mean arterial, mean right atrial, mean pulmonary arterial and mean pulmonary arterial occlusion pressure along with an increase in cardiac output. The systemic vascular and pulmonary vascular resistances were decreased. Renal venous blood flow and renal vascular resistance were not significantly changed after infusion of contrast media. There were no differences in haemodynamic effects between the two media studied.