Microvascular pressure and functional capillary density in extreme hemodilution with low- and high-viscosity dextran and a low-viscosity Hb-based O2 carrier

2004 ◽  
Vol 287 (1) ◽  
pp. H363-H373 ◽  
Author(s):  
Pedro Cabrales ◽  
Amy G. Tsai ◽  
Marcos Intaglietta
Keyword(s):  
Blood Pressure ◽  
Capillary Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Capillary Density ◽  
High Viscosity ◽  
Functional Capillary Density ◽  
Plasma Expander ◽  
Arterial Blood ◽  
Plasma Expanders

Blood losses are usually corrected initially by the restitution of volume with plasma expanders and subsequently by the restoration of oxygen-carrying capacity using either a blood transfusion or possibly, in the near future, oxygen-carrying plasma expanders. The present study was carried out to test the hypothesis that high-plasma viscosity hemodilution maintains perfused functional capillary density (FCD) by preserving capillary pressure. Microvascular pressure responses to extreme hemodilution with low- (LV) and high-viscosity (HV) plasma expanders and an exchange transfusion with a polymerized bovine cell-free Hb (PBH) solution were analyzed in the awake hamster window chamber model ( n = 26). Systemic hematocrit was reduced from 50% to 11%. PBH produced a greater mean arterial blood pressure than the nonoxygen carriers. FCD was higher after a HV plasma expander (70 ± 15%) vs. PBH (47 ± 12%). Microvascular pressure spanning the capillary network was higher after a HV plasma expander (16–19 mmHg) compared with PBH (12–16 mmHg) and a LV plasma expander (11–14 mmHg) but lower than control (22–26 mmHg). FCD was found to be directly proportional to capillary pressure. The use of a HV plasma expander in extreme hemodilution maintained the number of perfused capillaries and tissue perfusion by comparison with a LV plasma expander due to increased mean arterial blood pressure and capillary pressure. The use of PBH increased mean arterial pressure but reduced capillary pressure due to vasoconstriction and did not maintain FCD.

Liberal vs. conservative vasopressor use to maintain mean arterial blood pressure during resuscitation of septic shock: an observational study

2007 ◽  
Vol 34 (1) ◽  
pp. 157-162 ◽  
Author(s):  
Sanjay Subramanian ◽  
Murat Yilmaz ◽  
Ahmer Rehman ◽  
Rolf D. Hubmayr ◽  
Bekele Afessa ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Septic Shock ◽  
Observational Study ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Arterial Blood ◽  
Vasopressor Use

Cerebral hemorrhage and edema following brain biopsy in rats: significance of mean arterial blood pressure

2000 ◽  
Vol 92 (1) ◽  
pp. 100-107 ◽  
Author(s):  
Helene Benveniste ◽  
Katie R. Kim ◽  
Laurence W. Hedlund ◽  
John W. Kim ◽  
Allan H. Friedman
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Neurosurgical Procedures ◽  
Shr Rats ◽  
Mr Microscopy ◽  
Content Type ◽  
Wky Rats ◽  
Arterial Blood ◽  
Fine Print

Object. It is taken for granted that patients with hypertension are at greater risk for intracerebral hemorrhage during neurosurgical procedures than patients with normal blood pressure. The anesthesiologist, therefore, maintains mean arterial blood pressure (MABP) near the lower end of the autoregulation curve, which in patients with preexisting hypertension can be as high as 110 to 130 mm Hg. Whether patients with long-standing hypertension experience more hemorrhage than normotensive patients after brain surgery if their blood pressure is maintained at the presurgical hypertensive level is currently unknown. The authors tested this hypothesis experimentally in a rodent model.Methods. Hemorrhage and edema in the brain after needle biopsy was measured in vivo by using three-dimensional magnetic resonance (MR) microscopy in the following groups: WKY rats, acutely hypertensive WKY rats, spontaneously hypertensive rats (SHR strain), and SHR rats treated with either sodium nitroprusside or nicardipine. Group differences were compared using Tukey's studentized range test followed by individual pairwise comparisons of groups and adjusted for multiple comparisons.There were no differences in PaCO2, pH, and body temperature among the groups. The findings in this study indicated that only acutely hypertensive WKY rats had larger volumes of hemorrhage. Chronically hypertensive SHR rats with MABPs of 130 mm Hg did not have larger hemorrhages than normotensive rats. There were no differences in edema volumes among groups.Conclusions. The brains of SHR rats with elevated systemic MABPs are probably protected against excessive hemorrhage during surgery because of greater resistance in the larger cerebral arteries and, thus, reduced cerebral intravascular pressures.

Cerebroelectrical Depression Following Surfactant Treatment in Preterm Neonates

PEDIATRICS ◽  
1992 ◽  
Vol 89 (4) ◽  
pp. 643-647 ◽  
Author(s):  
Lena Hellström-Westas ◽  
Nils W. Svenningsen ◽  
Angela H. Bell ◽  
Liselotte Skov ◽  
Gorm Greisen
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Intraventricular Hemorrhage ◽  
Preterm Neonates ◽  
Cerebral Function ◽  
Surfactant Treatment ◽  
Arterial Blood ◽  
Cerebral Dysfunction ◽  
Almost All

During surfactant treatment of respiratory distress syndrome, 23 premature newborns were investigated with continuous amplitude-integrated electroencephalography (cerebral function monitors). Simultaneously, arterial blood pressure and transcutaneous blood gas values were recorded. A short(<10 minutes) but significant decrease in cerebral activity was seen in almost all neonates immediately after the surfactant instillation, in spite of an improved pulmonary function. In 21 of 23 neonates, a transient fall in mean arterial blood pressure of 9.3 mm Hg (mean) occurred coincidently with the cerebral reaction. Neonates in whom intraventricular hemorrhage developed tended to have lower presurfactant mean arterial blood pressure (P> .05), but they had a significantly lower mean arterial blood pressure after surfactant instillation (P < .05). No other differences were found between neonates in whom intraventricular hemorrhage developed and those without intraventricular hemorrhage. The present findings demonstrate that an acute cerebral dysfunction may occur after surfactant instillation. In some vulnerable neonates with arterial hypotension and severe pulmonary immaturity,the fall in mean arterial blood pressure may increase the risk of cerebral complications and could be related to an unchanged rate of intraventricular hemorrhage after surfactant treatment.

Plasma viscosity regulates systemic and microvascular perfusion during acute extreme anemic conditions

2006 ◽  
Vol 291 (5) ◽  
pp. H2445-H2452 ◽  
Author(s):  
Pedro Cabrales ◽  
Amy G. Tsai
Keyword(s):  
Flow Distribution ◽  
Capillary Density ◽  
High Viscosity ◽  
Plasma Viscosity ◽  
Functional Capillary Density ◽  
Microvascular Perfusion ◽  
Arterial Blood ◽  
Chamber Model ◽  
Kidney Liver ◽  
Window Chamber

The hamster window chamber model was used to study systemic and microvascular hemodynamic responses to extreme hemodilution with low- and high-viscosity plasma expanders (LVPE and HVPE, respectively) to determine whether plasma viscosity is a factor in homeostasis during extreme anemic conditions. Moderated hemodilution was induced by two isovolemic steps performed with 6% 70-kDa dextran until systemic hematocrit (Hct) was reduced to 18% ( level 2). In a third isovolemic step, hemodilution with LVPE (6% 70-kDa dextran, 2.8 cP) or HVPE (6% 500-kDa dextran, 5.9 cP) reduced Hct to 11%. Systemic parameters, cardiac output (CO), organ flow distribution, microhemodynamics, and functional capillary density, were measured after each exchange dilution. Fluorescent-labeled microspheres were used to measure organ (brain, heart, kidney, liver, lung, and spleen) and window chamber blood flow. Final blood and plasma viscosities after the entire protocol were 2.1 and 1.4 cP, respectively, for LVPE and 2.8 and 2.2 cP, respectively, for HVPE (baseline = 4.2 and 1.2 cP, respectively). HVPE significantly elevated mean arterial pressure and CO compared with LVPE but did not increase vascular resistance. Functional capillary density was significantly higher for HVPE [87% (SD 7) of baseline] than for LVPE [42% (SD 11) of baseline]. Increases in mean arterial blood pressure, CO, and shear stress-mediated factors could be responsible for maintaining organ and microvascular perfusion after exchange with HVPE compared with LVPE. Microhemodynamic data corresponded to microsphere-measured perfusion data in vital organs.

Effect of the Ace Inhibitor Ceronapril on Cerebral Blood flow in Hypertensive Patients

1996 ◽  
Vol 30 (6) ◽  
pp. 578-582 ◽  
Author(s):  
Neal R Cutler ◽  
John J Sramek ◽  
Azucena Luna ◽  
Ismael Mena ◽  
Eric P Brass ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Diastolic Blood Pressure ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Enzyme Inhibitor ◽  
Blood Pressure Response ◽  
Combined Therapy ◽  
Arterial Blood

Objective To assess the effect of the angiotensin-converting enzyme inhibitor ceronapril on cerebral blood flow (CBF) in patients with moderate hypertension. Design Patients received chlorthalidone 25 mg for 4 weeks, and if diastolic blood pressure remained in the range of 100–115 mm Hg, they were given titrated doses of ceronapril (10–40 mg/d based on blood pressure response) in addition to chlorthalidone for 9 weeks. Setting Outpatient research clinic. Subjects Eligible patients had moderate essential hypertension (diastolic blood pressure 100–115 mm Hg) assessed when the patients were receiving no medications. Thirteen patients were entered into the study; 1 withdrew for reasons unrelated to the study drug. Twelve patients (11 men, 1 woman; mean age 52 y) completed the study. Intervention Ceronapril, given with chlorthalidone. Main Outcome Measures CBF measurements were taken at the start and end of ceronapril therapy using intravenous 133Xe; blood pressures were determined weekly. Results Mean arterial blood pressure decreased from 130 ± 4 to 120 ±7 mm Hg after 4 weeks of chlorthalidone administration, and fell further to 108 ± 8 mm Hg after an additional 9 weeks of combined chlorthalidone-ceronapril therapy (p < 0.05). CBF fell from 44 ± 15 to 34 ± 5 mL/min/100 g during the 9 weeks of combined therapy (p = 0.05). No adverse effects consistent with decreased CBF were observed. The decrease in CBF was not linearly correlated with the change in systemic blood pressure, but was strongly correlated (r = –0.937; p < 0.001) with the initial CBF. Conclusions The decrease in mean arterial blood pressure was not associated with a decrease in CBF. Patients with high CBF may be predisposed to a decrease in CBF when treated with ceronapril and chlorthalidone.

The Study of Dynamic Response to Acute Hemorrhage by Pulse Spectrum Analysis

2006 ◽  
Vol 34 (03) ◽  
pp. 449-460 ◽  
Author(s):  
Yu Hsin Chang ◽  
Chia I Tsai ◽  
Jaung Geng Lin ◽  
Yue Der Lin ◽  
Tsai Chung Li ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Steady State ◽  
Arterial Blood Pressure ◽  
Mean Arterial Blood Pressure ◽  
Spectrum Analysis ◽  
Pulse Spectrum ◽  
Acute Hemorrhage ◽  
Arterial Blood ◽  
Percentage Difference ◽  
Before And After

Traditional Chinese Medicine (TCM) holds that Blood and Qi are fundamental substances in the human body for sustaining normal vital activity. The theory of Qi, Blood and Zang-Fu contribute the most important theoretical basis of human physiology in TCM. An animal model using conscious rats was employed in this study to further comprehend how organisms survive during acute hemorrhage by maintaining the functionalities of Qi and Blood through dynamically regulating visceral physiological conditions. Pulse waves of arterial blood pressure before and after the hemorrhage were taken in parallel to pulse spectrum analysis. Percentage differences of mean arterial blood pressure and harmonics were recorded in subsequent 5-minute intervals following the hemorrhage. Data were analyzed using a one-way analysis of variance (ANOVA) with Duncan's test for pairwise comparisons. Results showed that, within 30 minutes following the onset of acute hemorrhage,the reduction of mean arterial blood pressure was improved from 62% to 20%. Throughout the process, changes to the pulse spectrum appeared to result in a new balance over time. The percentage differences of the second and third harmonics, which were related to kidney and spleen, both increased significantly than baseline and towards another steady state. Apart from the steady state resulting from the previous stage, the percentage difference of the 4th harmonic decreased significantly to another steady state. The observed change could be attributed to the induction of functional Qi, and is a result of Qi-Blood balancing activity that organisms hold to survive against acute bleeding.

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