Impact of hetastarch on the intestinal microvascular barrier during ECLS.
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The effects of hetastarch on microvascular fluid flux were determined in anesthetized dogs undergoing extracorporeal life support (ECLS) with a roller pump and membrane oxygenator. ECLS with a lactated Ringer priming solution resulted in a decrease in microvascular protein reflection coefficient and an increase in transvascular protein clearance. Use of a 6% hetastarch priming solution attenuated the decrease in microvascular protein reflection coefficient and blunted the increase in transvascular protein clearance. Ileal tissue water increased in the group treated with the lactated Ringer priming solution compared with the group treated with 6% hetastarch. The effective plasma-to-interstitial colloid osmotic pressure gradient was greater in the group treated with hetastarch than in the group treated with lactated Ringer solution. Hetastarch decreases the edema associated with ECLS. The reduction in edema is due to the maintenance of the plasma-to-interstitial colloid osmotic pressure gradient and the reduction in the microvascular permeability to protein. (+info)
Safety of acute normovolemic haemodilution with hydroxyethyl starch during intracranial surgery.
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The effect of acute normovolemic haemodilution on haemodynamics, serum osmolality and coagulation parameters was studied in 20 patients undergoing intracranial surgical procedures. After induction of anaesthesia, 740+/-153 ml of blood was collected and the same was replaced with an equal volume of 6% hexaethyl starch. Heart rate (HR), blood pressure (BP), central venous pressure (CVP) and end tidal carbon dioxide tension (Et CO2) were monitored for 45 min. Haemoglobin concentration (Hb), haematocrit (Hct), serum osmolality (Osm), bleeding time (BT), prothrombin time (PT) and platelet count were determined before and 45 min after haemodilution. Hb and Hct were significantly lower following haemodilution (13.1+/-1.8 and 10.3+/-1.7 g/dL for Hb and 38.0+/-4.6%. and 30.1+/-4.5% for Hct). There was no significant change in the HR, BP and Et CO2 throughout the study period. CVP increased marginally from 35 to 45 min but was within normal limits. There was no significant change in serum osmolality, bleeding time and prothrombin time following haemodilution. Platelet count decreased following haemodilution but the values were within normal limits. The brain relaxation, as assessed by a semiquantitative scale, was satisfactory in all cases. None of the patients developed intraoperative brain swelling. In conclusion, acute normovolemic haemodilution with hexaethyl starch is tolerated well haemodynamically. It does not cause changes in serum osmolality which can increase brain oedema. It has no adverse effect on intraoperative haemostasis. It is a safe technique to decrease homologous blood transfusion during intracranial surgery. (+info)
Preparation for regional anaesthesia induces changes in thrombelastography.
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The effects of crystalloid and colloid infusions on coagulation measured by thrombelastography (TEG) present a confused picture. The influence of environmental factors may explain the disparity between previous studies. We studied two groups of 20 women presenting at term for elective Caesarean section. In the first group, TEG analysis was performed before and after infusion of Gelofusine 500 ml over 15 min. The second group was treated in the same way except that subjects did not receive fluid. We found significant changes in r and k values in both groups, suggesting enhanced coagulation. As hypercoagulable changes were also seen in the group that did not receive fluid preload, the hypothesis that moderate haemodilution causes hypercoagulability must be questioned. The influence of environmental factors can explain differences reported between in vivo and in vitro studies. (+info)
Conjugation of hydroxyethyl starch to desferrioxamine (DFO) modulates the dual role of DFO in Yersinia enterocolitica infection.
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The iron chelator desferrioxamine (DFO) B is widely used in the therapy of patients with iron overload. As a side effect, DFO may favor the occurrence of fulminant Yersinia infections. Previous work from our laboratory showed that this might be due to a dual role of DFO: growth promotion of the pathogen and immunosuppression of the host. In this study, we sought to determine whether conjugation of DFO to hydroxyethyl starch (HES-DFO) may prevent exacerbation of Yersinia infection in mice. We found HES-DFO to promote neither growth of Yersinia enterocolitica nor mitogen-induced T-cell proliferation and gamma interferon production by T cells in vitro. Nevertheless, in vivo HES-DFO promoted growth of Y. enterocolitica possibly due to cleavage of HES and release of DFO. The pretreatment of mice with DFO resulted in death of all mice 2 to 5 days after application of a normally sublethal inoculum of Y. enterocolitica, while none of the mice pretreated with HES-DFO died within the first 7 days postinfection. However, some of the HES-DFO-treated mice died 8 to 14 days postinfection. Thus, due to the delayed in vivo effect HES-DFO failed to trigger Yersinia-induced septic shock, which accounts for early mortality in DFO-associated septicemia. Moreover, our data suggest that DFO needs to be taken up by host cells in order to exert its immunosuppressive action. These results strongly suggest that HES-DFO might be a favorable drug with fewer side effects than DFO in terms of DFO-promoted fulminant infections. (+info)
Blood pressure control in a larval amphibian, Xenopus laevis.
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The regulation of arterial pressure in early vertebrate embryos and larvae with non-innervated hearts is poorly understood. We used nanoliter intravascular injections in anaesthetized Xenopus laevis larvae (stage 49-51) to assess their ability to maintain arterial pressure in the face of a volume load. Injections of saline and hetastarch (a volume expander) were made into the ventricle. Arterial pressure, end-diastolic ventricular volume, end-systolic ventricular volume and heart rate were measured. Injection of 800 nl caused a rapid rise in arterial pressure and stroke volume. There were no changes in heart rate, indicating the absence of an arterial baroreflex. Blood pressure in saline-injected animals recovered quickly (within 5 min), whereas hetastarch injections caused hypertension to be maintained for much longer, for over 40 min in the most extreme case. We surmise that Starling forces at the capillary play an important role in pressure regulation but are not adequate to explain the entire response. Finally, there was ample evidence for a Frank-Starling relationship in the ventricle. (+info)
The fine structure of pulmonary contusion and the effect of various drugs.
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The results of contusion were examined by electron and light microscopy in the lungs of rats. It was found that the results here were very similar to those elsewhere in the body, with a few minor modifications due to the unique structure of the lung. Densitometry of protein concentration and visual estimation of oedema were used to quantitate the effects on the injury. The benzo-pyrone drug Venalot had a considerable effect in reducing the protein concentration in the air spaces and the interstitial tissue, and of the oedema in the latter. Neither the proteinase inhibitor Trasylol nor the pectin-based plasma expander HAS had any significant effect on the fine structural alterations of pulmonary contusion. (+info)
Postoperative hypertensive-hypervolaemic-haemodilution (Triple H) therapy in the treatment of vasospasm following aneurysmal subarachnoid haemorrhage.
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Twenty five patients with post operative ischaemic deficits, following clipping of intracranial aneurysms, were studied. Hypertensive-hypervolaemic-haemodilution (triple H) therapy was given to all patients using colloids and crystalloids. CVP was used to monitor the fluid therapy. Dopamine was needed in 22 patients to elevate the systemic blood pressure. Vasospasm was confirmed in 20 patients with transcranial doppler studies (TCD). 20 (80%) patients survived, 10 (40%) with good outcome, 7 (28%) with fair, 2 (8%) with poor outcome and 1 (4%) with vegetative state. There were 5 (20%) deaths, 4 of which occurred due to infarct. All these patients had poor Hunt and Hess grade at admission, high Fisher grade haemorrhages in the initial CT scan and/or required prolonged temporary clipping at surgery. One death occurred due to central venous line induced septicaemia. The duration of 'triple H therapy' amongst the survivors varied from 2-7 days with an average of 4.6 days. The complications of 'triple H therapy' included hypokalaemia (3 patients), haemorrhagic infarct (1 patient) and septicaemia (1 patient). It is concluded that 'triple H therapy' is useful in treating vasospasm induced ischaemic deficits. It worsens brain oedema in presence of acute infarcts and hence is contraindicated in such patients. A further study involving a larger number of patients with strict haemodynamic and ICP monitoring is suggested to determine the usefulness of individual components of 'triple H therapy'. (+info)
Do fluid administration and reduction in norepinephrine dose improve global and splanchnic haemodynamics?
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We studied global and splanchnic haemodynamics in patients with septic shock, while reducing norepinephrine doses by progressive fluid loading administration. Ten patients (six female, four male, aged 39-86 yr, mean 61 yr) were assessed using a transpulmonary thermo-dye dilution technique to measure cardiac output, intrathoracic blood volume and total blood volume. Splanchnic blood flow was measured by the steady state indocyanine green technique using a hepatic venous catheter. Gastric mucosal blood flow was estimated by regional carbon dioxide tension (PRCO2). Hydroxyethylstarch was infused in two stages while maintaining mean arterial pressure, allowing a reduction in norepinephrine dose from 0.54 to 0.33 to 0.21 microgram kg-1 min-1. Mean (SD) heart rate significantly decreased, from 104 (13) to 94 (15) beats min-1. Total blood volume index (mean (SD)) increased from 2650 (638) to 3655 (885) ml m-2, intrathoracic blood volume index from 888 (204) to 1050 (248) ml m-2 and cardiac index from 3.6 (1.0) to 4.0 (0.9) litres min-1 m-2. Splanchnic blood flow did not change significantly--either absolute (from 0.81 to 0.98 litres min-1 m-2) or fractional (from 22.3% to 23.9%). Gastric mucosal (PRCO2) increased from 7.5 (2.5) to 9.0 (2.8) kPa. The PCO2 gap, i.e. the difference between regional and end-tidal PCO2, increased from 3.1 (2.5) to 4.0 (2.9) kPa. Marked individual variation in responses suggests that norepinephrine dose reduction by fluid loading in patients with stabilized septic shock does not necessarily increase global or splanchnic blood flow. (+info)