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Background: Jehovah's Witness (JW) patients strictly refuse allogeneic blood transfusion for religious reasons. Nevertheless, JW also wish to benefit from modern therapeutic concepts including major surgical procedures without facing an excessive risk of death. The Northwest Hospital in Frankfurt am Main Germany is a confidential clinic of JW and performs approximately 100 surgical interventions per year on this patient group.Material and Methods: A retrospective analysis of closed medical cases performed in the years 2008-2018 at the Northwest Hospital aimed to clarify (1) the frequency of surgical procedures in JW patients associated with a statistical allogeneic transfusion risk (presence of preoperative anemia and/or in-house transfusion probability >10%) during this time period, (2) the degree of acceptance of strategies avoiding blood transfusion by JW and (3) the anemia-related postoperative mortality rate in JW patients.Results: In the 11- year observation period 123 surgical procedures with a relevant allogeneic transfusion risk were performed in 105 JW patients. Anemia according to World Health Organization (WHO) criteria was present in 44% of cases on the day of surgery. Synthetic and recombinant drugs (tranexamic acid, desmopressin, erythropoetin, rFVIIa) were generally accepted, acute normovolemic hemodilution (ANH) in 92% and cell salvage in 96%. Coagulation factor concentrates extracted from human plasma and therefore generally refused by JW so far, were accepted by 83% of patients following detailed elucidation. Out of 105 JW patients 7 (6.6%) died during the postoperative hospital stay. In 4 of the 7 fatal cases the cause of death could be traced back to severe postoperative anemia.Conclusion: Given optimal management JW patients can undergo major surgery without an excessive risk of death. The 6.6% in-hospital mortality observed in this institution was in the range of the 4% generally observed after surgery in Europe. The majority of JW patients accepted a variety of blood conservation strategies following appropriate elucidation. This also included coagulation factor concentrates extracted from human plasma enabling an effective treatment of even severe bleeding complications. In this analysis postoperative hemoglobin concentrations below 6 g/dl in older JW patients were associated with a high mortality risk due to anemia. [ABSTRACT FROM AUTHOR]

Oxygen (O(2)) is the most frequently used pharmaceutical in anesthesiology and intensive care medicine: Every patient receives O(2) during surgery or during a stay in the intensive care unit. Hypoxia and hypoxemia of various origins are the most typical indications which are mentioned in the prescribing information of O(2): the goal of the administration of O(2) is either an increase of arterial O(2) partial pressure in order to treat hypoxia, or an increase of arterial O(2) content in order to treat hypoxemia. Most of the indications for O(2) administration were developed in former times and have seldom been questioned from that time on as the short-term side-effects of O(2) are usually considered to be of minor importance. As a consequence only a small number of controlled randomized studies exist, which can demonstrate the efficacy of O(2) in terms of evidence-based medicine. However, there is an emerging body of evidence that specific side-effects of O(2) result in a deterioration of the microcirculation. The administration of O(2) induces arteriolar constriction which will initiate a decline of regional O(2) delivery and subsequently a decline of tissue oxygenation. The aim of the manuscript presented is to discuss the significance of O(2) as a pharmaceutical in the clinical setting. [ABSTRACT FROM AUTHOR]

The religious organization of Jehovah's Witnesses numbers more than 7 million members worldwide, including 165,000 members in Germany. Although Jehovah's Witnesses strictly refuse the transfusion of allogeneic red blood cells, platelets and plasma, Jehovah's Witness patients may nevertheless benefit from modern therapeutic concepts including major surgical procedures without facing an excessive risk of death. The present review describes the perioperative management of surgical Jehovah's Witness patients aiming to prevent fatal anemia and coagulopathy. The cornerstones of this concept are 1) education of the patient about blood conservation techniques generally accepted by Jehovah's Witnesses, 2) preoperative optimization of the cardiopulmonary status and correction of preoperative anemia and coagulopathy, 3) perioperative collection of autologous blood, 4) minimization of perioperative blood loss and 5) utilization of the organism's natural anemia tolerance and its acute accentuation in the case of life-threatening anemia. [ABSTRACT FROM AUTHOR]

Oxygen (O) is the most frequently used pharmaceutical in anesthesiology and intensive care medicine: Every patient receives O during surgery or during a stay in the intensive care unit. Hypoxia and hypoxemia of various origins are the most typical indications which are mentioned in the prescribing information of O: the goal of the administration of O is either an increase of arterial O partial pressure in order to treat hypoxia, or an increase of arterial O content in order to treat hypoxemia. Most of the indications for O administration were developed in former times and have seldom been questioned from that time on as the short-term side-effects of O are usually considered to be of minor importance. As a consequence only a small number of controlled randomized studies exist, which can demonstrate the efficacy of O in terms of evidence-based medicine. However, there is an emerging body of evidence that specific side-effects of O result in a deterioration of the microcirculation. The administration of O induces arteriolar constriction which will initiate a decline of regional O delivery and subsequently a decline of tissue oxygenation. The aim of the manuscript presented is to discuss the significance of O as a pharmaceutical in the clinical setting. [ABSTRACT FROM AUTHOR]

The religious organization of Jehovah’s Witnesses numbers more than 7 million members worldwide, including 165,000 members in Germany. Although Jehovah’s Witnesses strictly refuse the transfusion of allogeneic red blood cells, platelets and plasma, Jehovah’s Witness patients may nevertheless benefit from modern therapeutic concepts including major surgical procedures without facing an excessive risk of death. The present review describes the perioperative management of surgical Jehovah’s Witness patients aiming to prevent fatal anemia and coagulopathy. The cornerstones of this concept are 1) education of the patient about blood conservation techniques generally accepted by Jehovah’s Witnesses, 2) preoperative optimization of the cardiopulmonary status and correction of preoperative anemia and coagulopathy, 3) perioperative collection of autologous blood, 4) minimization of perioperative blood loss and 5) utilization of the organism’s natural anemia tolerance and its acute accentuation in the case of life-threatening anemia. [ABSTRACT FROM AUTHOR]

Intraoperative surgical blood loss is initially replaced by infusion of red cell-free, cristalloidal or colloidal solutions. When normovolemia is maintained the ensuing dilutional anemia is compensated by an increase of cardiac output and of arterial oxygen extraction. In the ideal case, a surgical blood loss can entirely be ‘bridged’ without transfusion by intraoperative normovolemic hemodilution. However major blood loss results in extreme hemodilution and the transfusion of red blood cells may finally become necessary to increase arterial oxygen content and to preserve tissue oxygenation. When transfusion has to be started before surgical control of bleeding has been achieved, parts of the red blood cells transfused will get lost, thereby increasing intraoperative transfusion needs. Beside red blood cell transfusion, arterial oxygen content can be rapidly increased by ventilating the patient with 100% oxygen (hyperoxic ventilation), thus enhancing the amount of physically dissolved oxygen in plasma (hyperoxia). In experimental and clinical studies hyperoxic ventilation has emerged as a simple, safe and effective intervention to enlarge the margin of safety for hemodynamic compensation and tissue oxygenation in hemodiluted subjects experiencing major bleeding. The hyperoxia-associated microcirculatory dysregulation and impaired tissue oxygenation known to take place in the presence of a physiologic hemoglobin concentration are not encountered in hemodiluted subjects. Hyperoxic hemodilution i.e. the combination of intraoperative extreme hemodilution and hyperoxic ventilation may therefore be considered a cost-effective, safe and efficient supplement to reduce allogeneic transfusion during surgical interventions associated with high blood losses. The vast majority of the experimental and clinical investigations this new concept is based on was initiated and performed under the guidance of Prof. Konrad Messmer.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Today, the technique to directly administer vasodilators via the airway to treat pulmonary hypertension and to improve pulmonary gas exchange is widely accepted among clinicians. The flood of scientific work focussing on this new therapeutic concept had been initiated by a fundamental new observation by Pepke-Zaba [1]and Frostell in 1991 [2]: Both scientists reported, that inhalation of exogenous nitric oxide (NO) gas selectively dilates pulmonary vessels without a concomittant systemic vasodilation. No more than another decade ago NO was identified as an important endogenous vasodilator [3]while having merely been regarded an environmental pollutant before that time. Although inhaled NO proved to be efficacious, alternatives were sought-after due to NO’s potential side-effects. In search for the ideal inhaled vasodilator another group of endogenous mediators – the prostanoids – came into the focus of interest. The evidence for safety and efficacy of inhaled prostanoids is – among a lot of other valuable work – based on a series of experimental and clinical investigations that have been performed or designed at the Institute for Surgical Research under the guidance and mentorship of Prof. Dr. med. Dr. h.c. mult. K. Messmer [4-19]. In the following, the current and newly emerging clinical applications of inhaled prostanoids and the experimental data which they are based on, will be reviewed.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The blood volume that has to be exchanged for crystalloids and/or colloids during acute normovolemic hemodilution (ANH) in order to reach a preset target hemoglobin concentration (hb) is usually predicted by the Bourke and Smith formula developed in 1974. This formula systematically overestimates the 'true' exchangeable blood volume (EBV), a fact that may potentially endanger patients because the target hb will be missed and the normovolemic anemia might turn out to be more severe than a priori intended. Our objective was to develop a more accurate mathematical model of hemodilution kinetics and to validate this new model in animals and in patients undergoing ANH.Methods: Twenty-two anesthetized beagle dogs and 18 patients under balanced anesthesia underwent isovolemic hemodilution with hydroxyethyl starch (HAES 6%, 200 000) to a target hb of 7 g dl-1 or 9 g dl-1, respectively. Exchangeable blood volume predicted by use of the different mathematical models was compared with the blood volume actually exchanged to meet the preset target hb.Results: Calculation of EBV by the Bourke and Smith formula (EBVB + S) systematically overestimated the volume actually exchanged (overestimation: dogs 15%, patients 20%), whereas our new iterative model predicted EBV (EBViterative) more reliably (overestimation: dogs 1%, patients 8%). In both cases EBVB + S differed significantly from the EBViterative.Conclusion: Exchangeable blood volume is predicted more accurately by the new iterative model than by the Bourke and Smith formula. The iterative model leads to an improvement in patient safety and provides a physiologically adequate basis for future studies investigating the efficacy of ANH in reducing allogenic blood transfusions. [ABSTRACT FROM AUTHOR]

Despite current recommendations on the management of pre-operative anaemia, there is no pragmatic guidance for the diagnosis and management of anaemia and iron deficiency in surgical patients. A number of experienced researchers and clinicians took part in an expert workshop and developed the following consensus statement. After presentation of our own research data and local policies and procedures, appropriate relevant literature was reviewed and discussed. We developed a series of best-practice and evidence-based statements to advise on patient care with respect to anaemia and iron deficiency in the peri-operative period. These statements include: a diagnostic approach for anaemia and iron deficiency in surgical patients; identification of patients appropriate for treatment; and advice on practical management and follow-up. We urge anaesthetists and peri-operative physicians to embrace these recommendations, and hospital administrators to enable implementation of these concepts by allocating adequate resources. [ABSTRACT FROM AUTHOR]

Background: During acellular replacement of an acute blood loss, hyperoxic ventilation (HV) increases the amount of O2 physically dissolved in the plasma and thereby improves O2 supply to the tissues. While this effect could be demonstrated for HV with inspiratory O2 fraction (FiO2) 0.6, it was unclear whether HV with pure oxygen (FiO2 1.0) would have an additional effect on the physiological limit of acute normovolemic anemia. Methods: Seven anesthetized domestic pigs were ventilated with FiO2 1.0 and subjected to an isovolemic hemodilution protocol. Blood was drawn and replaced by a 6% hydroxyethyl starch (HES) solution (130/0.4) until a sudden decrease of total body O2 consumption (VO2) indicated the onset of O2 supply dependency (primary endpoint). The corresponding hemoglobin (Hb) concentration was defined as 'critical Hb' (Hbcrit). Secondary endpoints were parameters of myocardial function, central hemodynamics, O2 transport and tissue oxygenation. Results: HV with FiO2 1.0 enabled a large blood-for-HES exchange (156 ± 28% of the circulating blood volume) until Hbcrit was met at 1.3 ± 0.3 g/dl. After termination of the hemodilution protocol, the contribution of O2 physically dissolved in the plasma to O2 delivery and VO2 had significantly increased from 11.7 ± 2 to 44.2 ± 9.7% and from 29.1 ± 4.2 to 66.2 ± 11.7%, respectively. However, at Hbcrit, cardiovascular performance was found to have severely deteriorated. Conclusion: HV with FiO2 1.0 maintains O2 supply to tissues during extensive blood-for-HES exchange. In acute situations, where profound anemia must be tolerated (e.g. bridging an acute blood loss until red blood cells become available for transfusion), O2 physically dissolved in the plasma becomes an essential source of oxygen. However, compromised cardiovascular performance might require additional treatment. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The patient's individual anemia tolerance is pivotal when blood transfusions become necessary, but are not feasible for some reason. To date, the effects of neuromuscular blockade (NMB) on anemia tolerance have not been investigated. Methods: 14 anesthetized and mechanically ventilated pigs were randomly assigned to the Roc group (3.78 mg/kg rocuronium bromide followed by continuous infusion of 1 mg/kg/min, n = 7) or to the Sal group (administration of the corresponding volume of normal saline, n = 7). Subsequently, acute normovolemic anemia was induced by simultaneous exchange of whole blood for a 6% hydroxyethyl starch solution (130/0.4) until a sudden decrease of total body O2 consumption (VO2) indicated a critical limitation of O2 transport capacity. The Hb concentration quantified at this time point (Hbcrit) was the primary endpoint of the protocol. Secondary endpoints were parameters of hemodynamics, O2 transport and tissue oxygenation. Results: Hbcrit was significantly lower in the Roc group (2.4 ± 0.5 vs. 3.2 ± 0.7 g/dl) reflecting increased anemia tolerance. NMB with rocuronium bromide reduced skeletal muscular VO2 and total body O2 extraction rate. As the cardiac index increased simultaneously, total body VO2 only decreased marginally in the Roc group (change of VO2 relative to baseline -1.7 ± 0.8 vs. 3.2 ± 1.9% in the Sal group, p < 0.05). Conclusion: Deep NMB with rocuronium bromide increases the tolerance of acute normovolemic anemia. The underlying mechanism most likely involves a reduction of skeletal muscular VO2. During acellular treatment of an acute blood loss, NMB might play an adjuvant role in situations where profound stages of normovolemic anemia have to be tolerated (e.g. bridging an unexpected blood loss until blood products become available for transfusion). Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background Changes in heart rate variability (HRV) during anaesthesia depend on multiple influences such as hypnosis, analgesia, surgical stress, and interacting drugs. Several recent studies have aimed to establish HRV-based monitoring tools to measure perioperative stress or anaesthetic depth. Although hyperoxic ventilation (HV) is known to alter autonomic cardiovascular regulation, there have been no studies investigating its influence on time- and frequency-domain analysis during general anaesthesia. Therefore, we have examined the effects of HV on cardiovascular neuroregulation of anaesthetized patients and conscious volunteers by analysis of relevant HRV parameters. Methods Fourteen healthy volunteers and 14 anaesthetized, ventilated ASA I patients sequentially breathed room air ( 0.21), pure oxygen ( 1.0), and then room air. During each episode, standardized HRV parameters were calculated from 5 min ECG recordings. Results HV significantly reduced HR and increased the standard deviation of RR interval values, the root mean square of successive RR interval differences, and the high-frequency (HF) power of the spectral components, whereas the low-frequency (LF) power and the LF/HF ratio of HRV were reduced in both groups. All changes were reversible after was reduced to normoxia. Conclusions In both healthy volunteers and anaesthetized patients, HV resulted in comparable and reversible changes of established HRV parameters. These changes might be relevant enough to bias HRV-based analgesia and anaesthesia monitoring and could result in a clinically relevant misinterpretation of HRV parameters as indicators of anaesthetic depth during HV. [ABSTRACT FROM PUBLISHER]

Previously undiagnosed anaemia is common in elective orthopaedic surgical patients and is associated with increased likelihood of blood transfusion and increased perioperative morbidity and mortality. A standardized approach for the detection, evaluation, and management of anaemia in this setting has been identified as an unmet medical need. A multidisciplinary panel of physicians was convened by the Network for Advancement of Transfusion Alternatives (NATA) with the aim of developing practice guidelines for the detection, evaluation, and management of preoperative anaemia in elective orthopaedic surgery. A systematic literature review and critical evaluation of the evidence was performed, and recommendations were formulated according to the method proposed by the Grades of Recommendation Assessment, Development and Evaluation (GRADE) Working Group. We recommend that elective orthopaedic surgical patients have a haemoglobin (Hb) level determination 28 days before the scheduled surgical procedure if possible (Grade 1C). We suggest that the patient's target Hb before elective surgery be within the normal range, according to the World Health Organization criteria (Grade 2C). We recommend further laboratory testing to evaluate anaemia for nutritional deficiencies, chronic renal insufficiency, and/or chronic inflammatory disease (Grade 1C). We recommend that nutritional deficiencies be treated (Grade 1C). We suggest that erythropoiesis-stimulating agents be used for anaemic patients in whom nutritional deficiencies have been ruled out, corrected, or both (Grade 2A). Anaemia should be viewed as a serious and treatable medical condition, rather than simply an abnormal laboratory value. Implementation of anaemia management in the elective orthopaedic surgery setting will improve patient outcomes. [ABSTRACT FROM AUTHOR]

OBJECTIVE:: Extreme anemia threatens myocardial oxygen supply by 1) a decline of arterial oxygen content and 2) by a decline of mean aortic pressure (MAP) and thus coronary perfusion pressure. Standard treatment of low arterial oxygen content includes ventilation with pure oxygen and the transfusion of red blood cells. However, it is unknown whether the stabilization of MAP and coronary perfusion pressure with norepinephrine as the sole therapeutic modality may also increase tolerance to extreme anemia and thus improve outcome. DESIGN:: Prospective, randomized, controlled study. SETTING:: Experimental animal laboratory of a university hospital. SUBJECTS:: A total of 28 anesthetized, mechanically ventilated pigs. INTERVENTIONS AND MEASUREMENTS:: In the first protocol, 14 anesthetized pigs were hemodiluted by exchange of whole blood for 6% hydroxyethyl starch (200,000:0.5) until the individual critical hemoglobin concentration was reached. For the next 6 hrs, animals were either observed without any further intervention (control group) or their MAP was maintained by adapted infusion of norepinephrine (norepinephrine group). The main outcome variable of this protocol was the 6-hr mortality in both groups. In the second protocol, 14 anesthetized pigs received hemodilution until death. In seven animals, no intervention was performed during the hemodilution procedure, whereas in the other seven animals, MAP was maintained at >60 mm Hg by adapted infusion of norepinephrine. The main outcome variable of this protocol was the maximum exchangeable blood volume until death. MAIN RESULTS:: MAP stabilization with norepinephrine reduced the 6-hr mortality at the critical hemoglobin concentration from 100% to 14%. Maintaining MAP by adapted norepinephrine infusion during the hemodilution procedure allowed for the exchange of 125 (110/126) (median [quartile 1/quartile 3]) mL/kg blood (163% of blood volume) in the norepinephrine group, whereas only 76 (73/91) mL/kg blood (104% of blood volume) could be exchanged in the control group. CONCLUSIONS:: Application of norepinephrine can be judged a first-line intervention to bridge acute anemia via a stabilization of MAP and coronary perfusion pressure. However, due to the relevant side effects of norepinephrine, its sole long-term use during extreme anemia without concomitant transfusion of erythrocytes is not advised. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the impact of prophylactic hyperoxic ventilation with Fio2 0.6 on the physiologic limit of acute normovolemic anemia. DESIGN: Prospective, controlled, randomized experimental study. SETTING: Experimental animal laboratory of a university hospital. SUBJECTS: Fourteen anesthetized domestic pigs. INTERVENTIONS: Animals were randomly ventilated with either Fio2 0.21 (group 0.21, n = 7) or Fio2 0.6 (group 0.6, n = 7), and acute anemia was induced by isovolemic blood-for-hydroxy-ethylstarch (HES) exchange using a 6% HES solution (130/0.4). MEASUREMENTS AND MAIN RESULTS: The blood-for-HES-exchange was continued until a sudden decrease of total body oxygen consumption indicated the onset of oxygen supply dependency (primary end point); the corresponding hemoglobin (Hb) concentration was defined as 'critical' (Hb(crit)). Secondary end points were changes in myocardial function, central hemodynamics, oxygen transport, and tissue oxygenation. Compared with room air ventilation (Fio2 0.21), hyperoxic ventilation with Fio2 0.6 enabled a larger blood-for-HES-exchange (139%, 124/156) of circulating blood volume vs. 87% (68/94, p < .05), until Hb(crit) was reached (1.5 g/dL [1.4/2.1] vs. 2.4 g/dL [2.0/2.8], p < .05). At Hb 2.4 g/dL (i.e., Hb(crit) in group 0.21), animals of group 0.6 still presented with superior oxygen transport, tissue oxygenation, and hemodynamic stability. However, hemodynamic and oxygen transport variables were found deteriorated more severely at Hb 1.5 g/dL (i.e., Hb(crit) of group 0.6) compared with group 0.21 at Hb 2.4 g/dL. CONCLUSION: During cell-free volume replacement, hyperoxic ventilation with Fio2 0.6 generates a readily usable plasmatic oxygen reserve and thereby increases the tolerance toward acute normovolemic anemia. [ABSTRACT FROM AUTHOR]

Fluid resuscitation from hemorrhagic shock is intended to abolish microcirculatory disorders and to restore adequate tissue oxygenation. Diaspirin cross-linked hemoglobin (DCLHb) is a hemoglobin-based oxygen carrier (HBOC) with vasoconstrictive properties. Therefore, fluid resuscitation from severe hemorrhagic shock using DCLHb was expected to improve perfusion pressure and tissue perfusion of kidneys and pancreas.In 20 anesthetized domestic pigs with an experimentally induced coronary stenosis, shock (mean arterial pressure 45 mmHg) was induced by controlled withdrawal of blood and maintained for 60 min. Fluid resuscitation (replacement of the plasma volume withdrawn during hemorrhage) was performed with either 10% DCLHb (DCLHb group,n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group,n = 10). Completion of resuscitation was followed by a 60-min observation period. Regional blood flow to the kidneys and the pancreas was measured by use of the radioactive microspheres method at baseline, after shock and 60 min after fluid resuscitation.All animals (10/10) resuscitated with DCLHb survived the 60-min observation period, while 5/10 control animals died within 20 min due to persisting subendocardial ischemia. In contrast to HSA survivors, pancreas and kidneys of DCLHb-treated animals revealed lower total and regional organ perfusion and regional oxygen delivery. Renal and pancreatic blood flow heterogeneity was higher in the DCLHb group.DCLHb-induced vasoconstriction afforded superior myocardial perfusion, but impaired regional perfusion of the kidneys and the pancreas. [ABSTRACT FROM AUTHOR]

Hemodilution reduces hematocrit (Hct) and blood oxygen content. Tissue oxygenation is mainly preserved by increased cardiac output. As myocardial O2-demands increase, coronary vasodilatation becomes necessary to increase myocardial blood flow. Myocardial ischemia occurs at a critical Hct-value (Hctcrit), with accompanying exhaustion of coronary reserve. Hyperoxic ventilation is known to both reverse peripheral tissue hypoxia at Hctcrit and also to induce coronary vasoconstriction. This study aimed to determine whether hyperoxic ventilation at Hctcrit further exacerbates myocardial ischemia and dysfunction. Nine anesthetized pigs ventilated on room air were hemodiluted by 1 : 1 exchange of blood with pentastarch (6%HES) to Hctcrit , defined as onset of myocardial ischemia (ECG changes). At Hctcrit , hyperoxic ventilation was started. Measurements were performed at baseline, at Hctcrit, and after 15 min of hyperoxic ventilation. We determined myocardial blood flow (microsphere method), arterial O2-content, subendocardial O2-delivery and myocardial function (left ventricular pressure increase). At Hctcrit 7 (6;8)%, O2-content was reduced [3.7 (3.1;3.9) ml dl−1]. Despite a compensatory increase of myocardial blood flow [531 (449;573), ml min−1100 g−1], all pigs displayed myocardial ischemia and compromised myocardial function ( P < 0.05). Hyperoxic ventilation produced increased coronary vascular resistance secondary to vasoconstriction, and reduced myocardial blood flow [426 (404;464), ml min−1100 g−1; P < 0.05]. Myocardial oxygenation was found to be maintained by increased O2-content [4.4 (4.2;4.8), ml dl−1; P < 0.05], the contribution of dissolved O2 to subendocardial O2-delivery increased (32 vs. 8%; P < 0.05), which preserved myocardial function. Hyperoxic ventilation at Hctcrit is followed by coronary vasoconstriction and reduction of coronary blood flow. However, myocardial oxygenation and function is maintained, as increased O2-content (in particular dissolved O2) preserves myocardial oxygenation. [ABSTRACT FROM AUTHOR]

Fluorescent microspheres (FM) have become an attractive alternative to radioactive microspheres (RM) for the measurement of regional blood flow (RBF). The aim of the present study was to investigate the comparability of both methods by measuring RBF with FM and RM. Eight anaesthetised pigs received simultaneous, left atrial injections of FM and RM with a diameter of 15 μm at six different time points. Blood reference samples were collected from the descending aorta. RBF was determined in tissue samples of the myocardium, spleen and kidneys of all 8 animals. After radioactivity of the tissue samples was determined, the samples were processed automatically for measuring fluorescence using a recently developed filter device (SPU). RBF was calculated with both the isotope and spectrometric data of both methods for each sample resulting in a total of 10,512 blood flow values. The comparison of the RBF values yielded high linear correlation (mean r[sup 2] = 0.95 ± 0.03 to 0.97 ± 0.02) and excellent agreement (bias 5.4–6.7%, precision 9.9– 16.5%) of both methods. Our results indicate the validity of MS and of the automated tissue processing technique by means of the SPU.Copyright © 2002 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In severe hemorrhagic shock, left ventricular (LV) diastolic dysfunction is an early sign of cardiac failure due to compromised myocardial oxygenation. Immediate fluid replacement or, in particular, administration of a hemoglobin-based oxygen carrier (diaspirin cross-linked hemoglobin; DCLHb) improves myocardial oxygenation; therefore, positive effects on LV diastolic function could be expected. The effects of fluid resuscitation from severe hemorrhagic shock with DCLHb were investigated in 20 anesthetized domestic pigs. After generation of a critical left anterior descending coronary artery stenosis (narrowing of the artery until disappearance of reactive hyperemia after a 10-second complete vessel occlusion), hemorrhagic shock (mean arterial blood pressure 45 mm Hg) was induced within 15 min by controlled blood withdrawal and maintained for 60 min. Fluid resuscitation consisted of replacement of the plasma volume withdrawn during hemorrhage by infusion of either 10% DCLHb (DCLHb group, n = 10) or 8% human serum albumin (HSA) oncotically matched to DCLHb (HSA group, n = 10). After completion of resuscitation, an observation period of 60 min elapsed. Measurements of central hemodynamics, myocardial oxygenation, and LV diastolic function were performed at baseline, after induction of critical coronary artery stenosis, after 60 min of hemorrhagic shock, immediately after resuscitation, and 60 min later. While 5 out of 10 animals treated with HSA died within the first 20 min after fluid resuscitation from acute LV pump failure, all DCLHb-treated animals survived until the end of the protocol (p < 0.05). Despite superior myocardial oxygenation due to augmentation of the arterial O[sub 2] content as well as of coronary perfusion pressure, no beneficial effects on LV diastolic function were observed after infusion of DCLHb. Peak velocity of LV pressure decrease (dp/dt[sub min] ) did not reveal significant differences between the two groups. Immediately after completion of fluid resuscitation with DCLHb, the time constant of LV diastolic relaxation (τ) was prolonged when compared with HSA-treated animals (p < 0.05), indicating retardation of early LV diastolic relaxation. Our data suggest that DCLHb fails to improve LV diastolic function after fluid resuscitation from severe hemorrhagic shock. However, positive effects on myocardial perfusion and oxygenation result in a significant reduction of the mortality of severe hemorrhagic shock.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background. Utilization of an individual patient's tolerance of anaemia is a cornerstone of any restrictive transfusion policy. Whether the use of neuromuscular block (NMB) has an effect on anaemia tolerance has not been investigated. Methods. Fourteen anaesthetized and mechanically ventilated pigs were randomized to receive either rocuronium bromide 1% (Roc-group, n=7, 0.378 ml kg-1 bolus injection, 0.1 ml kg-1 min-1 continuous infusion) or the same volume of normal saline (Sal-group, n=7). Acute normovolaemic anaemia was induced by exchange of whole blood for a 6% HES-solution (130/0.4) until a sudden decrease in total body O2 consumption (VO2) indicated a critical limitation of O2 delivery to the tissues. The Hb concentration quantified at this critical time point (HbCRIT) was defined as the primary endpoint of the protocol. Secondary endpoints were parameters of central haemodynamics, O2 transport, and tissue oxygenation. Results. HbCRIT was significantly lower in the Roc-group [2.4 (0.5) vs 3.2 (0.7) g dl-1] reflecting increased tolerance of anaemia. NMB with rocuronium bromide reduced skeletal muscle O2 consumption (mVO2) and the total body O2 extraction ratio. As cardiac index increased, body O2 consumption (VO2) decreased marginally in the Roc-group [change of VO2 relative to baseline (ΔVO2) -1.7 (0.8)% vs 3.2 (1.9)% in the Sal-group, P<0.05]. Conclusions. NMB with rocuronium bromide increases the tolerance of acute normovolaemic anaemia. The underlying mechanism probably involves a reduction in skeletal muscle O2 consumption. During acellular treatment of acute blood loss, NMB might play an adjuvant role, particularly in situations where profound normovolaemic anaemia has to be tolerated, for example, bridging an acute blood loss until compatible blood products become available for transfusion. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about a clinical case of a patient who survived from continous tumor bleeding and dilutional anemia due to aortic valve stenosis.