Peripheral Vascular Resistance Index Research Articles

The application of pulse indication contour cardiac output to early fluid resuscitation in patients with septic shock

Objective To explore the use of pulse indication contour cardiac output (PiCCO) as a guidance for fluid resuscitation and vasopressors employment in patients with septic shock in order to find out the efficacy of this resuscitation strategy in the respect of outcome of patients. Mtthod A total of 30 patients with septic shock were treated with the EDGT fluid treatment protocol as the conventional treatment group from December 2006 to June 2008; and another 26 patients were given fluid treatment under the guidance of PiCCO as PiCCO group from July 2008 to October 2009. Exclusion criteria included patients with history of heart and lung diseases, and liver and kidney dysfunction. The mean arterial blood pressure was maintained above or equal to 65mmHg in PiCCO group,and fluid resuscitation was concluded when global end-diastolic volume index reached 600～750 mL·-2 with the stroke volume variation in ＜ 10% and without auricular fibrillation. Nor-epinephrine was administrated to adiust the systemic peripheral vascular resistance index during 1300～1500 d·s·cm-5·m-2.Dobutamine was empoyed when global ejection fraction was compromised. The options of liquid and diuretics depend upon the presence d extra-vascular lung water. Central venous oxygen saturation and the level of lactate were observed 6hours after resuscitation. The liquid equilibrium for 3 days and the dosage of vasopressors were also recorded. The rate of survival, the time taken for weaning from mechanical ventilation, the days of ICU stay and rate of intact organ function within 28 days were compared between two groups. Results The demphics of patients of two goups were similar. There were no significant difference between PiCCO and the conventional group in values of central venous oxygen saturation and lactate 6 hours after admission to ICU (P ＞ 0.05). And 6 h and 1d after fluid resuscitation, the dosages of dobutamine and the dosages of nor-epinephrine used in PiCCO group were significantly higher than those in conventional group in which the dosages of dobutamine in two groups were [(145.4±24.5)mg vs. (104.2 ± 46.3) mg and (330.2 ± 30.3) mg vs. (202.4 ± 40.3) mg], respectively, and the dosages of nor-epinephrine [(14.5±3.8) mgvs. (10.2±5.6) mgand (38.2±4.2) rng vs.(20.1±6.2) mg], respectively. However, the dosages of vasopressors were similar between two groups 2 d and 3 d later. The amounts of liquid administered to get equilibrium in 6 h and the 3 d in PiCCO group were significantly less than those in conventional group [(2121±578) mL vs. (2910±987) mL and (3845±435) mL vs. (4545 ± 765) mL and (2467±510) mLvs. (2867±618) mL and (951±332) mLvs. (1472±533) mL], respectively. The days required to get free from mechanical ventilation within 28d were significantly longer in PiCGO group[(19.7 ± 8.3) d vs.(15.1±9.1) d], but the days of ICU stay were significantly shorter in PiCCO group [(7.5 ± 3.5) d vs. (9.5±3.2) d] (P＜0.05). The rates of survival and days free from organ failure within 28 days of two groups were similar(P＞0.05). Conclusions When the early fluid management guided with PiCCO in septic shock patients,the fluid management can be implement more safely and precisely. It can shorten the days of ICU stay and days of mechanical ventilation support with avoidance of fluid resuscitation. Key words: Septic shock; Pulse indicate Contour Cardiac Output; Fluid management; Mortality

Complex Therapy for Intraoperative Blood Loss during Pelvic Bone Repair

Objective: to introduce blood saving technologies and to develop algorithms for management of patients with pelvic fractures. Subjects and methods. Sixty patients aged 40.6±2.3 years with pelvic fractures were examined. The banking of packed autoerythrocytes and auto freshly frozen plasma (AutoFFP), intraoperative acute hypervolemic hemodilution (AHH), and instrumental reinfusion of washed autoerythrocytes were made in all the patients. Blood loss volume averaged 32.1±1.7 ml/kg. The parameters of central hemodynamics (CH), blood oxygen-transport function, the blood system (red blood cells, hemoglobin, packed cell volume, and platelets) were studied. AutoFFP was transfused in the most traumatic period of surgery, autoblood was on completion of surgical hemostasis, and washed autoerythrocytes were within 3—4 hours after surgery. Postoperative reductions in hemoglobin to below 80 g/l and packed cell volume below 25% are indications for packed autoerythrocyte transfusion. Results. During preoperative autoblood banking, the parameters of CH and the blood system underwent no changes, all variations in the parameters were within the normal range and compensatory. When AHH and instrumental washed erythrocyte reinfusion were conducted, there was a significant increase in cardiac index (CI), stroke index by 37 and 30%, respectively; reductions in total peripheral vascular resistance index by 38%, mean blood pressure by 18%, moderate hypercoagulation, and significant decreases in hemoglobin, packed cell volume, red blood cells by 17, 15, and 18%, respectively. The values of acid-base condition and homeostasis underwent no considerable changes. Arterial blood O2 content was significantly lowered by 16%; however, global O2 uptake remained unchanged at the baseline levels due to the increase of CI by 30% of the baseline level. Conclusion. The application of blood saving technologies, preoperative autoblood banking in particular, AHH, and instrumental washed autoerythrocyte reinfusion allowed a refusal to use allo-geneic blood components during pelvic repair, by preventing the development of hemotransfusion complications. Key words: blood loss, blood saving, packed autoerythrocytes, auto freshly frozen plasma, acute hypervolemic hemodilution, autohemotransfusion, instrumental washed autoerythrocyte reinfusion, spinal epidural anesthesia.

EFFECTS OF VENTRICULAR GEOMETRY ON VENTRICULAR ARTERIAL COUPLING IN ESSENTIAL HYPERTENSION: PP.8.341

Introduction: Echocardiography is used to assess ventrículo-arterial coupling (VAC) determined by the balance between the contractile properties of left ventricle (LV) and the pressure load. However ventricular geometry (VG) and cardiac hypertrophy (LVH) may modulate the VAC in hypertension (HT). Adaptative variations of aortic (Eal) and ventricular (Ees) elastances may be related with VAC changes within normal systolic function (SF). Objective: To characterize non-invasively the interaction between VG and VAC in HT within normal range of SF and VAC. Methods: We evaluated 23 consecutives hypertensive patients, age 53,3 ± 9,8, male 12(52,2%) female 11 (47,8%), SBP 134,78 ± 12,8 mmHg, DBP 82,47 ± 8,21 mmHg, with Doppler Echocardiography (Vivid 7,GE), using simple pulse method modified for the calculation of Ees and the ratio of end systolic pressure to stroke volume for Eal. VAC is the ratio Eal/Ees.Elastances were normalized to 100 g of ventricular mass. The following measurements were also determined: Mesoparietal fractional shortening, normalized systolic stress (MFS/STRESS), left atrial diameter (LA), correlation E/A (E/A), diastolic isovolumic relaxation time (Tau), systolic work index (SWI), systolic volume index (SVI) and peripheral vascular resistance index (PVRI). The VG was classified as: normal (Nor), concentric remodeling (Rem), concentric LVH (Conc) and eccentric LVH (Exc). Results: Significative differences on the VG were found in Nor with Rem: Ees(p < 0,05); Conc: LA(p < 0,01), Eal(p < 0,01), E/A(p < 0,01), SWI(p < 0,05); Exc: SWI(p < 0,05), SVI(p < 0,05), LA(p < 0,05), Eal(p < 0,01). Conclusions: In HT with SF and VAC within normal ranges, VG seems to affect VAC, contractility and ventricular performance. The noninvasive measurement of VG and related VAC, may be useful for diagnostic and therapeutic porpoises in early stages in hypertensive patients.

Ways of Improving the Results of Treatment for Pulmonary Thromboembolism

Objective: to reveal the predictors of clinically significant deterioration of cardiac pump function resulting from alveolar opening maneuver (AOM) (mobilization) made early after extracorporeal circulation during standard cardiosurgery. Subjects and methods. Hemodynamic, clinical, and laboratory parameters were analyzed in 20 cardiosurgical patients who had undergone AOM in the early postperfusion period. The study inclusion criteria were a PaO2/FiO2 ratio of less than 350 mm Hg, a cardiac index (CI) of more than 2.5 l/min/m2, a dosage of dopamine and/or dobutamine of not more than 10 ^g/kg/min, and standard AOM performance (Pmax, 30—35 cm H2O; end-expiratory pressure (PEEP), 13—15 cm H2O). Regression analysis was used to identify the predictors of a clinically significant reduction in CI (less than 2.5 l/min/m2). Results. Before and after AOM, CI was 3.1±0.1 and 2.9±0.1 l/min/m2, respectively (p&gt;0.05); however, CI was less than 2.5 l/min/m2 (2.16±0.09 l/min/m2) in 25% of cases. After AOM, CI values were significantly related to those recorded prior to a respiratory procedure (p=0.039), total peripheral vascular resistance index (TPVRI) (p=0.00039), and intrapulmonary blood shunt fraction (Qs/Qt) (p=0.041). There were no relationships to other recorded and estimated hemodynamic parameters (p&gt;0.1). &#8211; After AOM, CI values were unrelated (p&gt;0.1) to the duration of extracorporeal circulation, the period of myocardial ischemia, and the used dosages of inotropic agents. The predictor of a clinically significant CI reduction after AOM was the only index TPVRI (p=0.00025) recorded before a respiratory procedure. Following AOM, the probability of a significant CI reduction substantially increased (the approximation coefficient R2=0.75) at TPVRI values of 2000 din^sec^cm-5^m2 or more. Conclusion. After AOM performed in the early period after extracorporeal circulation, CI values are related to the baseline level of CI, TPVRI, and Qs/Qt; however, after this procedure only the value of TPVRI is a reliable predictor of clinically significantly depressed cardiac pump function. The risk of persistent car-diodepression is highest at TPVRI values of 2000 din^sec^cm-5^m2 or more. AOM should be carried out early after extra-corporeal circulation in cardiosurgical patients, by making an invasive monitoring that makes it possible to maximally correctly evaluate central hemodynamics, including CI and TPVRI. Key words: alveolar opening maneuver (mobilization), lung recruitment, recruiting maneuver in cardiosurgical patients, central hemodynamics during lung recruitment, cardiodepression during lung recruitment.

Predictors of the Cardiodepressive Effect of Alveolar Opening Maneuver (Mobilization) in Cardiosurgical Patients

Objective : to reveal the predictors of clinically significant deterioration of cardiac pump function resulting from alveolar opening maneuver (AOM) (mobilization) made early after extracorporeal circulation during standard cardiosurgery. Subjects and methods. Hemodynamic, clinical, and laboratory parameters were analyzed in 20 cardiosurgical patients who had undergone AOM in the early postperfusion period. The study inclusion criteria were a PaO 2 /FiO 2 ratio of less than 350 mm Hg, a cardiac index (CI) of more than 2.5 l/min/m 2 , a dosage of dopamine and/or dobutamine of not more than 10 μg/kg/min, and standard AOM performance (P max , 30—35 cm H 2 O; endexpiratory pressure (PEEP), 13—15 cm H 2 O). Regression analysis was used to identify the predictors of a clinically significant reduction in CI (less than 2.5 l/min/m 2 ). Results . Before and after AOM, CI was 3.1±0.1 and 2.9±0.1 l/min/m 2 , respectively ( p >0.05); however, CI was less than 2.5 l/min/m 2 (2.16±0.09 l/min/m 2 ) in 25% of cases. After AOM, CI values were significantly related to those recorded prior to a respiratory procedure ( p =0.039), total peripheral vascular resistance index (TPVRI) ( p =0.00039), and intrapulmonary blood shunt fraction (Qs/Qt) ( p =0.041). There were no relationships to other record ed and estimated hemodynamic parameters (p>0.1). After AOM, CI values were unrelated (p>0.1) to the duration of extracorporeal circulation, the period of myocardial ischemia, and the used dosages of inotropic agents. The predictor of a clinically significant CI reduction after AOM was the only index TPVRI (p=0.00025) recorded before a respiratory procedure. Following AOM, the probability of a significant CI reduction substantially increased (the approximation coefficient R2=0.75) at TPVRI values of 2000 din•sec•cm-5•m2 or more. Conclusion. After AOM performed in the early period after extracorporeal circulation, CI values are related to the baseline level of CI, TPVRI, and Qs/Qt; however, after this procedure only the value of TPVRI is a reliable predictor of clinically significantly depressed cardiac pump function. The risk of persistent cardiodepression is highest at TPVRI values of 2000 din•sec•cm-5•m2 or more. AOM should be carried out early after extracorporeal circulation in cardiosurgical patients, by making an invasive monitoring that makes it possible to maximally correctly evaluate central hemodynamics, including CI and TPVRI.

Influence of the 6‑month anemia therapy with erythropoietin on renal function and some hemodynamic parameters in predialysis patients

The aim of this study was to evaluate the influence of a 6-month anemia therapy with recombinant human erythropoietin (rHuEpo) on glomerular filtration rate (GFR) and renal blood flow related to hemoglobin (Hb) concentration, changes in heart function and total peripheral resistance in patients with chronic kidney disease (CKD) treated conservatively. We evaluated 13 patients (9 women and 4 men) aged 64.8 +/- 8.9 years with serum creatinine of 3.82 +/- 1.30 mg/dl and Hb concentration of 10.02 +/- 0.45 g/dl. rHuEpo was given in the mean dose of 2296 +/- 673 U/week s.c. to achieve Hb 12 g/dl. At baseline and after 6 months of rHuEpo therapy echocardiography and renoscintigraphy were performed. After 6 months' therapy Hb increased significantly, while blood pressure did not change significantly. Renal anemia correction led to a decrease in left ventricular end-diastolic dimension index, left ventricular end-diastolic volume index, stroke volume index and cardiac index. Total peripheral vascular resistance index increased significantly. At the same time a significantly reduced left ventricular mass index was observed. Correction of renal anemia and changes in systemic hemodynamics did not exert unfavorable effect on renal hemodynamic parameters. GFR index, blood flow rate index, renal vascular resistance index and filtration fraction remained unchanged. During rHuEpo therapy decline in renal function expressed as 1/serum creatinine did not differ compared with a 6-month period before initiating rHuEpo therapy. Therapy with rHuEpo in patients with stage 3 and 4 CKD with correct blood pressure control does not result in worsening of renal function despite changes in left ventricular function and increase of total peripheral resistance.

Systemic hemodynamic effects of sequential pneumatic compression of the lower limbs: a prospective study in healthy volunteers

Study ObjectiveTo evaluate the effects on systemic hemodynamics of sequential pneumatic compression of the lower limbs in healthy volunteers. DesignProspective, self-controlled, volunteer study. SettingUniversity teaching hospital. Patients11 healthy volunteers, aged 25 ± 1.3 years. Interventions and MeasurementsAfter volunteers underwent a 6-hour period of fasting and 15 minutes of rest in the supine position, baseline systemic hemodynamics were assessed using transthoracic electrical bioimpedance. Peripheral venous pressure was measured using a 16-gauge intravenous cannula inserted in the forearm and connected to a pressure monitor. Then sequential pneumatic compression of the lower limbs was activated for a 30-minute period, and systemic hemodynamic measurements were repeated. In each volunteer, measurements were repeated twice in two consecutive days, and average values were calculated for each volunteer. Main ResultsAfter activation of sequential pneumatic compression of the lower limbs, mean arterial blood pressure increased from 90 mmHg (79-107 mmHg) to 95 mmHg (79-129 mmHg) (P = 0.02), whereas heart rate decreased from 79 bpm (51-94 bpm) to 75 bpm (53-90 bpm) (P = 0.02). This was associated with a significant increase in peripheral vascular resistance index (from 545 [440-1066] to 613 [369-1280] dynes s cm−5 m−2 [P = 0.013]) and reduction in cardiac index (from 3.4 [2.7- 4.5] to 3.2 [2.5-4.0] L/min per m2 [P = 0.034]). ConclusionsThe application of sequential pneumatic compression to the lower limbs is associated with minor increases in mean arterial blood pressure, with moderate reduction of cardiac output and heart rate.

Investigation of Various Types of Neurocardiogenic Response to Head‐Up Tilting by Extended Hemodynamic and Neurohumoral Monitoring

The pathophysiology of neurocardiogenic syncope is heterogeneous. This study aim was to analyze whether extended monitoring during tilt-table testing provided additional information on the hemodynamic and vegetative state prior to neurocardiogenic syncope. This retrospective analysis is based on data of head-up tilt-table testing of 40 unselected consecutive patients with a history of unexplained syncope. For optimized characterization of the type of syncope, monitoring included electrocardiogram (ECG), blood pressure measurements and cardiac output, peripheral vascular resistance and contractility index measurements by impedance cardiography, as well as epinephrine and norepinephrine plasma levels in supine position and every 5 min during tilting. Seven of 40 patients were unsuitable for analysis because of incomplete data sets. Tilt-table was positive in 26 patients, negative in 7. Groups did not differ in hemodynamic and catecholaminergic parameters at baseline. Responses to tilting were VASIS 1 (mix of cardioinhibitory and vasodepressor) in 5 patients, VASIS 2B (cardioinhibitory with asystole >3 sec) in 3, VASIS 3 (vasodepressor) in 16, orthostatic dysregulation in 2. In VASIS 1, the catecholamine measurement 4 min before syncope showed a proportionally larger increase of the epinephrine level than of norepinephrine. This disproportion was not observed in VASIS 2B and 3. In VASIS 2B, strong vasoconstriction and negative inotropy were evident in the presyncopal period. In VASIS 3, vascular resistance decreased continuously before syncope, while contractility index increased inadequately. Presyncopal epinephrine surge or norepinephrine loss was not observed in this group, suspecting other vasodilating factors. Extended monitoring by impedance cardiography and plasma catecholamine measurements during tilt-table testing gave further insight into different hemodynamic and neurohumoral presyncopal patterns among the various types of neurocardiogenic syncope and may thereby help to develop individualized therapeutic concepts.

Physiological changes during hemodialysis in patients with intradialysis hypertension

Intradialysis hypertension is a frustrating complication among hemodialysis (HD) patients. This study was conducted to investigate the physiological changes during intradialytic hypertension. The beat-to-beat continuous heart rate, hematocrit (Hct) changes during HD, serum levels of nitric oxide, plasma levels of catecholamine, renin, endothelin (ET-1), cardiac output (CO), and peripheral vascular resistance (PVR) were measured before and after HD in patients prone to develop intradialysis hypertension (n = 30) and from age, sex-matched control HD subjects (n = 30). It was found that the baseline values of Hct, serum levels of nitric oxide, plasma levels of catecholamine, renin, and ET-1, CO, PVR, and power index (low frequency/high frequency ratios) of heart rate variability were not significantly different between the patients and control subjects. In the hypertension-prone group, the plasma levels of catecholamine, renin, and the serial measurements of power index, did not show significant changes. However, the patients showed a significant elevation of systemic vascular resistance (56.8 +/- 9.2% vs 17.7 +/- 9.5; P < 0.05), ET-1 (510.9 +/- 43.3 vs 276.7 +/- 30.1 pg/ml; P < 0.05) and a significant decrease of nitric oxide (NO)/ET-1 balance (0.018 +/- 0.003 vs 0.034 +/- 0.005; P < 0.05) at the end of HD compared with the control patients. It was found that the physiological changes in intradialysis hypertension patients were characterized by inappropriately increased PVR through mechanisms that did not involve sympathetic stimulation or renin activation but might be related with altered NO/ET-1 balance.

Maternal nonpregnant vascular function correlates with subsequent fetal growth

Evidence is accumulating that fetal growth is influenced by preexisting maternal disorder(s) hampering endothelial function. We tested the hypothesis that in nonpregnant normotensive, formerly preeclamptic women, vascular function predicts the development of fetal growth restriction. In 60 formerly preeclamptic women, we measured central hemodynamic and vascular and clotting function mid follicular phase during the menstrual cycle. Inclusion for final analysis required besides normotension, a subsequent singleton pregnancy, established within 1 year after the prepregnant evaluation and ongoing beyond 16 weeks' gestation. In the ongoing pregnancy we determined birth weight and birth weight percentile. Among 60 formerly preeclamptic women, 45 (75%) were normotensive. Thirty-one (69%) participants succeeded in establishing an ongoing pregnancy within 1 year and were included for final analysis. Of the 31 subsequent pregnancies, 8 (26%) were complicated by fetal growth restriction. Prepregnant left and right uterine artery pulsatility index (PI) correlated inversely with carotid artery compliance ( r = 0.57, P = .005, r = 0.62, P = .002) and venous compliance ( r = 0.49, P = .02 and r = 0.45, P = .04, respectively). The latter, in turn, correlates with plasma volume ( r = 0.63, P = .001) and total peripheral vascular resistance index ( r = -0.45, P = .02). Finally, prepregnant left and right uterine artery PI correlated inversely with subsequent achieved fetal growth ( r = -0.68, P < .0001 and r = -0.58, P = .001, respectively). In nonpregnant normotensive, formerly preeclamptic women, an elevated uterine artery PI predisposes to subsequent restriction in fetal growth.

Kardiorespiratorische Effekte von Heliox an einem Modell der oberen Atemwegsobstruktion / Cardiorespiratory effects of Heliox using a model of upper airway obstruction

Heliox is a mixture of Oxygen and Helium. The low density of Helium allows this mixture to flow in a laminar pattern where oxygen, nitrogen or air flow would be turbulent. Therefore the force necessary to move a volume of gas (e.g. Heliox) is greatly reduced in comparison to a turbulent gas flow. In a respiratory loading experiment we investigated the effects which Heliox exerts on hemodynamic as well respiratory variables. 10 volunteers were breathing spontaneously and through three different endotracheal (ET-) tubes (ID 4.0, 4.5, 5.0 mm). The subjects were switched from room air to Heliox and differences in the variables heart rate (HR), blood pressure (BP), stroke volume (SV), stroke index (SI), peripheral vascular resistance (TPRI) and left ventricular work index (LVWI) were measured. Furthermore the (PhAng) between abdomen and thorax was detected using respiratory inductance plethysmography (n=2) and the sense of dyspnoe under the different conditions was assessed by the use of a dyspnea score (DS). The means of BP, SV, SI, TPRI and LVWI did not significantly differ between the resting and the different loading conditions irrespective of the gas that was used. The variability of hemodynamic measures was significant larger during loaded vs. unloaded breathing. Heliox could significantly reduce this degree of variability. In two subjects Heliox could also significantly reduce the PhAng as well as DS. Heliox showed effects on hemodynamic as well as respiratory and subjective variables. These effects can be interpreted as a reduction of the extent of pressure variations in the intrapleural space leading to less impact on hemodynamic variables while breathing Heliox vs. room air in a resistive loading experiment. In the future the combined measurement of hemodynmic variables as well as non-invasive assessment of respiration might shed new light on cardio-respiratory interaction and effects of Heliox during airway obstruction.

A 4-Amino Analogue of Tetrahydrobiopterin Attenuates Endotoxin-Induced Hemodynamic Alterations and Organ Injury in Rats

Most recently we have shown that 4-aminotetrahydrobiopterin (4-ABH4), an analogue of tetrahydrobiopterin (cofactor of NO synthase), even administered 2 h after endotoxin challenge, improves survival rate in rats. The following experiment was performed to examine the effects of 4-ABH4 with respect to endotoxin-induced hemodynamic alterations and organ failure. At 2 h after endotoxic challenge (10 mg kg(-1) body weight) animals received 4-ABH4 at a dose of 1, 10, or 100 mg kg(-1) body weight. The controls were treated similarly but received saline at the same volume. Eight hours after endotoxin challenge cardiac index and stroke volume were significantly increased in animals treated with 10 mg 4-ABH4 compared to controls (0.23 +/- 0.06 vs. 0.16 +/- 0.04 mL min(-1) kg(-1) and 0.29 +/- 0.05 vs. 0.22 +/- 0.03 mL beat(-1)) while mean arterial pressure and peripheral vascular resistance index did not significantly differ among the groups. Plasma alanine aminotransferase (ALT) and creatinine levels were significantly increased in endotoxin controls compared with laboratory controls (ALT: 1643 +/- 1436 vs. 74 +/- 17 U L(-1); Creatinine: 91 +/- 29 vs. 42 +/- 3 micromol L(-1)) which was attenuated in animals treated with 10 mg kg(-1) 4-ABH4 (ALT: 417 +/- 318 U L(-1); Creatinine: 78 +/- 26 micromol L(-1)). Moreover, endotoxin-induced lung edema and intestinal necrosis were significantly reduced by 4-ABH4. Our study provides information that tetrahydrobiopterin analogue, 4-ABH4, improves LPS induced hemodynamic conditions and organ injury. This may, at least in part, account for the previously observed protection of rats by 4-ABH4 against endotoxin-induced mortality in the same endotoxic shock model.

Effects of controlled blood cooling on hemodynamic stability and urea kinetics during high-efficiency hemodialysis.

Although the use of cooled dialysate during hemodialysis is associated with stabilization of intradialytic BP, the effects of blood cooling on hemodynamics and urea kinetics in high-efficiency hemodialysis have not been completely studied. In particular, the effects of blood cooling have not been elucidated in very short-time, high K/V dialysis treatments, in which postdialysis urea rebound is maximized. In theory, blood cooling could increase urea compartmentalization during treatment and decrease dialysis efficacy. Measurements of cardiovascular hemodynamics and urea kinetics were performed in 15 patients (56 studies) during dialysis, using a blood temperature monitor with control of dialysate temperature. Dialysate temperature was adjusted to either lower the core temperature or raise the core temperature by, respectively, producing negative heat-energy exchange (cooled dialysis) or keeping heat-energy exchange in the extracorporeal circuit neutral (thermoneutral dialysis) so that energy was not transferred to or from the patient. Each subject was studied on both protocols, thereby allowing each individual to act as his own control. In cooled dialysis, heat-energy exchange in the extracorporeal circuit was -266+/-15 kJ per treatment, and dialysate temperature averaged 35.7+/-0.02 degrees C. In thermoneutral dialysis, heat-energy exchange in the extracorporeal circuit averaged 5+/-31 kJ per treatment, and dialysate temperature averaged 37.1+/-0.02 degrees C. Dialysate cooling resulted in a reduction in mean body temperature compared with thermoneutral therapy (-0.22+/-0.04 versus +0.31+/-0.05 degrees C). Cooling resulted in a greater increase in peripheral vascular resistance index (+515+/-160 versus + 114+/-92 dyn.sec/cm5 per m2), an increase in mean arterial pressure (+4+/-3 versus -4+/-4 mmHg), a reduction in the maximum intradialytic fall in mean arterial pressure (-10+/-2 versus -18+/-3, mmHg), and a reduction in staff interventions for hypotension or dialytic symptoms (6 of 28 versus 12 of 28 studies). These differences occurred without differences in the change in blood volume (-14.3+/-1.8% versus -13.9+/-2.2%) or cardiac index (-0.4+/-0.1 versus -0.4+/-0.2, L/min per m2). Urea rebound (37+/-4% versus 38+/-3%) and effective Kt/V (1.29+/-0.05 versus 1.32+/-0.06) were not different between groups. Thus, body temperature cooling can be used to stabilize BP and reduce intradialytic events requiring staff intervention without compromising the efficacy of treatment in high-efficiency dialysis.

Effect of posture-induced blood volume expansion on systemic and regional hemodynamics in patients with cirrhosis

Background/Aims: This study aimed to investigate the effects of posture-induced blood volume expansion on systemic and regional hemodynamics in patients with cirrhosis. Methods: The mean arterial pressure, cardiac index, peripheral vascular resistance index, and flow volume index of the superior mesenteric artery (SMA) and femoral artery (FA) were measured in 10 patients with cirrhosis and portal hypertension and 10 controls after they had been standing for 2 h. Plasma atrial natriuretic peptide, plasma renin activity, and plasma glucagon levels were also determined. These measurements were repeated after 30 min and 60 min when the patients were recumbent. Results: In the upright posture, systemic hemodynamics, FA blood flow index, plasma atrial natriuretic peptide level, and plasma renin activity level were similar in patients and controls. However, SMA blood flow index and plasma glucagon level were significantly higher in patients than in controls. On the assumption of the supine position, cardiac index and plasma atrial natriuretic peptide level significantly increased in the two groups, but the changes were greater in patients than in controls. Mean arterial pressure remained unchanged. The reduction in peripheral vascular resistance index was therefore greater in patients than in controls. SMA and FA blood flow index increased significantly in the two groups, but the changes were greater in patients than in controls. Furthermore, SMA blood flow fraction (SMA blood flow index/cardiac index) was steady in controls, whereas it increased significantly in patients. In contrast, FA blood flow fraction (FA blood flow index/cardiac index) remained unchanged in the two groups. In patients, the change in peripheral vascular resistance index was correlated inversely with that of SMA blood flow index, but not with that of FA blood flow index. Plasma renin activity level dropped significantly, but the decline was similar in the two groups. Plasma glucagon level was not modified in either group. Conclusions: In patients with cirrhosis, splanchnic vasodilation appears to be present, even in the upright position, and further abnormal vasodilation oocurs on recumbency-induced blood volume expansion. This abnormal shear-stress phenomenon observed in the splanchnic circulation seems to be mediated by a local vasodilator rather than a general vasodilator.

Effects ofl-arginine andN-nitro-l-arginine treatment on hemodynamics, DO2, VO2, and extravascular lung water in a dog endotoxin shock model

To verify the effect of nitric oxide pathway modification during sepsis, experiments were conducted in four groups of anesthetized dogs which received lipopolysaccharide (LPS) intravenously (group 1), 300 mg·kg(-1) ofL-arginine plus LPS (group 2), 20 mg·kg(-1) ofN-nitro-L-arginine plus LPS (L-NNA, group 3), and normal saline as the control group. Hemodynamic and oxygenation data as well as extravascular lung water (EVLW) were measured or calculated. The results showed thatL-arginine increases cardiac output index (CI) and decreased the peripheral vascular resistance index (PVRI) without a significant influence on oxygen extraction ratio (O2ER), oxygen delivery (DO2), or oxygen consumption (VO2). All of the untoward hemodynamic effects of LPS were exacerbated by the addition ofL-NNA. Therefore, as DO2 was significantlys decreased byL-NNA, and although O2ER was increased (insufficiently), VO2 was still decreased significantly. EVLW was markedly increased byL-NNA. These results support the hypothesis that inhibition of nitric oxide synthesis may exacerbate hemodynamic and oxygenation consequences in septic shock.

Central vasopressin in experimental aortic stenosis in the rat

In several forms of heart disease characterised by low cardiac output, activated neurohumoral systems including increased vasopressin plasma levels play a key role in the changes in cardiovascular function. The aim of this study was to test the hypothesis that under such conditions the central vasopressin system might also be altered, which could contribute to deranged cardiovascular control. Aortic stenosis was produced in 22 rats by placing a Silver clip (inner diameter 0.6 mm) on the ascending aorta. After 12 weeks, haemodynamic and hormonal measurements were performed, and vasopressin content was determined in 20 microdissected brain areas (micropunch technique). Twenty two sham operated rats served as controls. Twelve weeks after placing the supravalvular clip, significant aortic stenosis was documented by left ventricular myocardial hypertrophy. Cardiac index was significantly reduced and the peripheral vascular resistance index was increased, while poststenotic aortic pressure was non-significantly decreased. Plasma renin concentration [6.8(SEM 0.9) v 2.1(0.2) ngAI.ml-1.h-1 in controls] and plasma vasopressin [32.9(12.5) v 18.4(6.0) pg.ml-1] were significantly increased, while plasma and urinary noradrenaline remained unaltered. The vasopressin content was significantly altered in eight out of 20 brain areas investigated. Concerning the vasopressin producing hypothalamic nuclei, concentrations were increased in the paraventricular [7494(360) v 4744(237) pg.mg-1 protein, P < 0.05] and suprachiasmatic [3613(170) v 1784(197) pg.mg-1 protein, P < 0.01], but not in the supraoptic nuclei. Rats with aortic stenosis showed significantly raised vasopressin concentrations in the median eminence [25 186(1682) v 37 367(1345) pg.mg-1 protein, P < 0.01], where the hormone is mainly concentrated in the hypothalamo-hypophysial tract. Vasopressin content was significantly decreased in locus coeruleus [49(5) v 89(6) pg.mg-1 protein], which is known to be involved in modulation of sympathetic activity. As well as showing increased secretion of vasopressin into the blood with consecutive peripheral antidiuretic and vasoconstrictive effects, these data suggest an alteration in the central vasopressin system in aortic stenosis which might transmit cardiovascular effects by neuromodulation and neuroregulation.

Differentiation of embolic and thrombotic middle cerebral artery occlusion using ultrasonic carotid flow velocity analysis

The purpose of this study was to determine the value of Duplex ultrasound of the carotid arteries in the differentiation of embolic from thrombotic middle cerebral artery (MCA) occlusion. We report here the results of carotid Duplex ultrasound study from 164 patients with acute ischemic stroke. Flow velocity and diameter were measured in bilateral common carotid arteries (CCA). The end-diastolic flow velocity (V ed) and the pulsatility index (PI) were calculated from Doppler waves. The PI is an index of peripheral vascular resistance. We compared the relationship between percent carotid stenosis and percent decrease in V ed. The patients studied could be classified into three groups using ultrasound parameters. Group I was characterized by >30% decrease in V ed and < 80% carotid stenosis, group II by < 30% decrease in V ed and < 80% carotid stenosis, and group III by >30% decrease in V ed and >80% carotid stenosis. All 23 patients in group I had embolic MCA stem occlusion. 28 out of 115 patients in group II had thrombotic MCA stem occlusions. All 26 patients in group III had internal carotid artery occlusion or severe stenosis. V ed was markedly reduced in group I and group III compared to group II ( p < 0.01). PI in the affected artery was increased in groups I and III ( p < 0.01). Embolic occlusion was characterized by >30% decrease in V ed in the absence of >80% carotid stenosis, and an increase in PI. The results indicate that these two conditions can be differentiated using Duplex ultrasound in carotid arteries.

Oxygen Transport Capacity and Hemodynamic Effect of Newly Developed Artificial Blood “Neo Red Cells (NRC)”

The purpose of this study was to evaluate liposome-encapsulated hemoglobin, named Neo Red Cells (NRC), on hemodynamics and oxygen-transport capacity in a blood exchange experiment. The experiment was carried out in nine mongrel dogs. Depending on the percentage of blood exchange with NRC, the animals were divided into two groups; Group I (4 animals with an exchange rate less than 88%), and Group II (5 animals with an exchange rate over 88%). After blood exchange, total peripheral vascular resistance index (TPRI) decreased and cardiac index (CI) increased. These changes were more marked in Group II than in Group I, thus showing that NRC relieved the burden on the heart, probably due to the fact that the viscosity of NRC is 2 cp which is less than 1/3 that of whole blood. The oxygen binding capacity per 1g hemoglobin in NRC was 2-4 times as much as red blood cells. Thus, NRC was superior to natural red blood cells in terms of oxygen transport capacity and its effects on the circulatory system.

Effect of recombinant human erythropoietin treatment on hemodynamic parameters in continuous ambulatory peritoneal dialysis and hemodialysis patients.

We studied the hemodynamic changes and the incidence of hypertension after correction of anemia with recombinant human erythropoietin (rhEPO) in 25 hemodialysis (HD) and in 27 continuous ambulatory peritoneal dialysis (CAPD) patients with a mean age of 44.6 years and a mean time on dialysis of 43.6 months. We analyzed basal and final hemoglobin concentrations, time elapsed to reach target hemoglobin, rhEPO dosage, and the following echocardiographic parameters: left ventricular end-systolic and end-diastolic diameters and volumes, posterior wall thickness, interventricular septum, ejection fraction, fractional fiber shortening, cardiac output index, and peripheral vascular resistance index. We did not find any significant difference between HD and CAPD patients in basal and final hemoglobin, concentrations, time elapsed to reach target hemoglobin, dose of rhEPO received for response, and incidence of hypertension. Changes were more evident in HD patients, with a decrease of 15% in cardiac output index and an equal increase of peripheral vascular resistance,. In the patients on CAPD, these variations were less important, with a decrease in cardiac output index of 10% and no significant change in peripheral vascular resistance. Despite both techniques showing the occurrence of hypertension, the left ventricular mass stabilized during the study time. We conclude that CAPD seems to modulate the changes observed in hemodynamic parameters after rhEPO treatment.

Study of effect of the newly developed artificial blood "Neo Red Cells (NRC)" on hemodynamics and blood gas transport in canine hemorrhagic shock.

The purpose of this study is to evaluate the newly developed liposome-encapsulated hemoglobin, named Neo Red Cells (NRC), in the treatment of hemorrhagic shock. The particle size of NRC is 180 +/- 88 nm, the hemoglobin concentration is 5.6 g/dl, the viscosity is 2 cp and P50 is 49.5 mmHg. The experiment was carried out on six mongrel dogs suffering hemorrhagic shock. Blood was extracted from the femoral artery and blood pressure became lower than 60 mmHg. NRC in amount equal to the amount of blood extracted was transfused immediately. Inhalating normal room air, the above manipulation was repeated 3-5 times. After 59% to 88% blood exchange using NRC, the total peripheral vascular resistance index (TPRI) was reduced and the cardiac index (CI) was increased, thereby alleviating the burden on the heart. The reduction of TPRI in the presence of hemorrhagic shock is presumed to be due to the small size of the NRC granules and their low viscosity. As the exchange rate increased, the oxygen consumption (VO2) increased remarkably, presumably due to the increase of CI and A-V difference of oxygen content. The conclusion of the study is that NRC is more suitable than natural blood for the treatment of hemorrhagic shock.