Influence of acute normovolaemic haemodilution on bispectral index monitoring and propofol dose requirements

BACKGROUND

Numerous medical and physiological conditions that might alter electroencephalography (EEG), such as hypoglycaemia, hypothermia or hypovolaemia, were shown to result in the bispectral Index (BIS) indicating an incorrect hypnotic state. Recently, acute normovolaemic haemodilution (ANH) was shown to be associated with significant impairment of cognitive functions that could alter EEG and consequently BIS monitoring, an EEG derived parameter.

METHODS

In a randomised clinical study, we assessed the effect of ANH on BIS monitoring before induction and after propofol target controlled infusion (TCI) anaesthesia in 45 unmedicated patients randomly allocated to ANH with oxygen insufflation (oxygen group), ANH with air insufflation (air group), or control group.

RESULTS

With ANH, mean BIS values briefly declined in the oxygen group (82+/-4) and air group (84+/-3) before returning to baseline values. The loss of consciousness time was significantly shorter, with fewer propofol TCI dose requirements, and BIS was significantly higher in the oxygen group (1.3+/-0.5 min, 2.41+/-0.15 microg/ml, 73+/-7) and air group (1.2+/-0.6 min, 2.44+/-0.17 microg/ml, 75+/-5), compared with the control group (1.7+/-0.4 min, 2.75+/-0.17 microg/ml, 61+/-5), respectively. Whereas, there was no significant difference in BIS values between the oxygen group (38+/-7), air group (36+/-5) and control group (40+/-6) at propofol TCI 4 microg/ml anaesthesia maintenance.

CONCLUSIONS

BIS values briefly declined with ANH before returning to baseline values before anaesthesia induction. Despite transient ANH enhancement of propofol effect during induction, there was no significant difference in BIS values with or without ANH during propofol maintenance of anaesthesia.

Acute normovolaemic haemodilution with crystalloids in coronary artery bypass graft surgery: a preliminary survey of haemostatic markers

INTRODUCTION

Acute normovolaemic haemodilution (ANH) is a safe and cost-effective blood conservation strategy in procedures with great blood loss. It eliminates the risk of administrative errors and also contaminations that may occur whenever banked blood is used. Classically, haemodilution is regarded as causing coagulopathy. This study was designed to determine the effect of crystalloids on measured coagulation values and perioperative blood loss following ANH in patients undergoing elective coronary revascularization.

METHODS

Following a prospective case-control study one hundred candidates for CABG (50 cases in the ANH group and 50 in the control group) were included. Blood samples for coagulation testing haematocrit and platelet levels were collected before ANH, after cardiopulmonary bypass (CPB), and upon arrival at the intensive care unit (ICU). Differences were considered statistically significant with P values < 0.05.

RESULT

There was no statistically significant difference between chest tube drainage in the two groups. The number of patients using PRBC (packed red blood cell) or FFP (fresh frozen plasma) was significantly higher in the control group in comparison to the ANH group (P < 0.05). The PT increased significantly after arrival in the ICU in both groups (P < 0.001) but there was no between-group difference (P = 0.22). aPTT not only did not change significantly in the ICU relative to the baseline pre ANH values in both groups (P > 0.05) but also did not show any between-group difference (P = 0.69). There was no statistically significant difference in the aCT of the control and the ANH group after arrival to the ICU (P = 0.09). Hct and Plt decreased significantly in both groups after CPB and arrival at ICU.

CONCLUSION

ANH reduced the need for PRBC and FFP by 58% and 74%, respectively. Regarding the increase in PT and decrease in Plt count, we concluded that performing ANH with saline solution (SS) in patients undergoing CABG surgery may cause a non-clinically significant change in coagulation state.

[Efficiency of using gelofusine and voluven in acute normovolemic hemodilution during cardiosurgical interventions]

The aim of the study was to assess the use of gelofusine and voluven for acute normovolemic hemodilution at cardiac surgery under extracorporeal circulation (EC). Sixty-seven patients with coronary heart disease were examined. Heart rate, total peripheral vascular resistance, pulmonary pressure, pulmonary artery wedge pressure, oxygen delivery and consumption, central venous pressure, arteriovenous oxygen difference, oncotic pressure, and postoperative clinical course were studied. No significant group differences were found in indices, other than arteriovenous oxygen difference, after acute normovolemic hemodilution and in central venous pressure following 6 hours of EC termination. The administration of gelofusine caused a more steady-state oxygen-transport function of the circulatory system. The use of the agent for acute normovolemic hemodilution at cardiac surgery under EC is more economically justified than that of volumen.

[Tactics of infusion therapy in the acute period of intracranial hemorrhages]

The paper deals with the determination of infusion therapy tactics in critically ill patients with intracranial hemorrhages on the basis of invasive measurements of systemic hemodynamics. The routine hemodynamic parameters (blood and central venous pressures, heart rate) are noted to fail to assess the volemic status of the patients in full. Unlike the use of colloidal solutions, infusion therapy with physiological sodium chloride is not shown to correct systemic hemodynamics. It has been ascertained that in acute intracranial hemorrhages, infusion therapy with crystalloidal solutions leads to impaired pulmonary gas exchange and increased pulmonary extravascular fluid and the use of a combination of crystalloidal solutions and a colloidal agent in a 1:1 ratio can correct the volemic status of the patients and is not followed by lung dysfunctions.

[Effect of the combined hypertonic colloidal solution HyperHeas on hemodynamic and oxygen transport parameters, intracranial pressure, and cerebral oxygenation]

The paper gives the results of a clinical study of the effect of the new combined hypertonic colloidal and hypertonic solution HyperHaes (Frezenius-Cabi) on the parameters of systemic hemodynamics (invasive evaluation by means of a Swan-Ganz catheter), systemic oxygen transport, intracranial pressure (ICP) (lumbar spinal fluid pressure), and cerebral oximetry (INVOS 5100) in neurosurgical patients. The paradoxical effect was found as acute blood pressure lowering and elevated ICP on the beginning of solution infusion (the vasodilator effect of a distinctly hyperosmolar agent). In all other respects, HyperHaes is an ideal agent for volumetric compensation in neurosurgical patients.

[Blood-sparing techniques in pediatric neuroanesthesiology]

The paper analyzes the clinical effectiveness of various blood-sparing techniques (hypervolemic hemodilution, isovolemic hemodilution, and instrumental infusion of washed autoerythrocytes) in neurosurgical interventions (n = 93) in 89 patients. Hypervolemic hemodilution that remains, however, to be the method of choice for young and low-weight children has proved to be the least clinically effective as a method for blood saving. The blood-sparing effectiveness of isovolmic hemodilution and instrumental reinfusion of washed autoerythrocytes is about the same, but the efficiency of reinfusion was higher with a blood loss volume of more than 100% of the proper volume of circulating complexes. A combination of hemodilution and instrumental reinfusion of autoerythrocytes provides a summation of blood-sparing effects for the mechanisms of blood saving vary with these techniques. The use of any blood-sparing technique accelerates and worsens hemostatic disorders.

Acute normovolemic haemodilution for management of blood loss during radical prostatectomy

INTRODUCTION

The reduction of the risks of anemia and allogeneic transfusion is one the basic parts of the anaesthesia management in large urological procedures. We used acute normovolemic haemodilution (ANH) as a technique of autologous blood procurement in patients scheduled for radical prostatectomy.

METHODS

15 patients undergoing radical prostatectomy were enrolled in our study. After starting general anaesthesia the left radial artery line was placed for invasive blood pressure monitoring and withdrawing blood for ANH. The restoration of circulated volume was instituted by infusion of crystalloids and colloids. Reinfusion of gained blood was started after transfusion trigger was reached (Hct 0.25).

RESULTS

The average total blood loss was in amount of 2393 +/- 238 (ml), autologous blood was infused in amount of 1919 +/- 220 (ml). The preoperative haematocrit was 41 +/- 3, after ANH 29 +/-2 and 31 +/- 3 (%) postoperatively. One unit of allogeneic blood was transfused in 2 patients only. All patients were hemodynamically stable during the entire surgery, with minimal systolic blood pressure of 100 mmHg and were extubated in the operation room with no complications.

CONCLUSIONS

This study demonstrated the effectiveness and safety of ANH as a method for avoiding the allogeneic blood transfusion in patients undergoing radical prostatectomy (Tab. 1, Ref. 10). Full Text (Free, PDF) www.bmj.sk.

[Foreign blood saving measures in orthopedic surgery]

Major transfusion-free orthopaedic surgery can be performed successfully. This requires advanced planning, good routines and close collaborative team efforts. Since most blood saving techniques reduce blood usage by just 1-2 units, a series of integrated preoperative, intraoperative and postoperative blood saving approaches is required. These include preoperative autologous donation, erythropoietic support, acute normovolemic hemodilution, intraoperative autotransfusion, individualized assessment of anemia tolerance, meticulous surgical techniques and the use of pharmacologic agents for limiting blood loss. For various reasons, we do not recommend the transfusion of wound drainage. This article describes the various methods for bloodless medical care.

Haemodilution induced by hydroxyethyl starches 130/0.4 is similar in septic and non-septic patients

BACKGROUND

Fluid therapy induces haemodilution related to plasma volume expansion. The aim of our study was to compare haemodilution after a single hydroxyethyl starches (HES) 130/0.4 infusion in two groups of patients, one with and one without sepsis. We hypothesized that a single HES challenge would induce similar sustained haemodilution in both groups.

METHODS

In this prospective preliminary study, patients predicted to require a single further volume-expander infusion were included immediately before receiving 500 ml of 6% HES 130/0.4 over a 15-min period. No additional fluid was administered over the next 8 h. Haematocrit, and serum albumin and protein were determined immediately before HES infusion then after 1, 2, 3, 4, and 8 h.

RESULTS

Twelve patients were included in each group. In both groups, all three haemodilution markers had significantly lower values after 1 h than at baseline. None of the values after 1 and 3 h differed significantly between the two groups. Neither did any of the other study variables show significant differences between the groups with and without sepsis.

CONCLUSION

We found that a starch-based compound was as effective in inducing haemodilution in patients with sepsis as in controls without sepsis, suggesting that HES may remain within the intravascular space even in patients with sepsis. Haemodilution parameters such as haematocrit, serum albumin and serum protein are useful for assessing the duration of plasma volume expansion induced by fluid therapy in critically ill patients.

[Current technologies for blood loss prevention during abdominal hysterectomy]

The paper deals with the development and use of original adequate transfusion-infusion programs to compensate for blood loss in abdominal hysterectomies for uterine myomas of varying sizes, by applying the current blood-supplying technologies that permit avoidance of transfusion of donor blood components. Four blood loss-replenishing programs in abdominal hysterectomy for large-sized myomas were studied for impact on the basic functions in premenopasal women. These included: (1) preoperative blood storage of blood autocomponents; (2) normovolemic hemodilution with hydroxyethyl starch (HES) solution being used as a dilutant; (3) administration of HES solutions as an independent solution compensating for blood loss, and (4) intraoperative reinfusion of autoerythrocytes. The proposed transfusion-infusion programs in abdominal hysterectomy for large-sized myomas by applying blood-preserving methods are effective in avoiding the use of donor blood components and accordingly in reducing the frequency of complications associated with transfusions of donor blood components, and improving the postoperative period.

[Application of acute extreme hypervolemic hemodilution in spine surgery]

OBJECTIVE

To evaluate the security and validity of the acute extreme hypervolemic hemodilution (AEHH) in spine surgery.

METHODS

Thirteen patients (8 males, 5 females; age, 16-65 years; weight, 50-75 kg) who had undergone major spine operations were enrolled in this study. Eleven of them had undergone anterior decompression, who were given the grafting and the internal fixation for their thoraco-lumber spinal burst fractures; the other 2 patients were given the correction operation for their scoliosis. The baselines of the haematocrit (Hct) were 0.363-0.481 before operation. The patients had no cardiac, pulmonary, hepatic or renal dysfunction or coagulation abnormality. The hemodynamic status and the haematocrit were observed during operation. The parameters of thromboelastography (TEG), arterial blood gas, and electrolytes were measured and observed at the following time points: before AEHH, after AEHH, 60 minutes after AEHH, 120 minutes after AEHH, and the end of the operation. The total fluid volume was recorded.

RESULTS

The autologous blood volume was 1 050-1 575 ml (average, 1 419 +/- 198 ml), plasma substitute 2 100-3 150 ml (average, 2 838 +/- 397 ml), blood loss 1 000-3 130 ml (average, 1 747 +/- 743 ml), urine 450-1 270 ml (average, 871 +/- 374 ml), and the net blood transfusion 1 206-2 661 ml (1 863 +/- 598 ml). The homogenous blood of 400 ml was transfused in 1 patient for making up the blood loss of 3 130 ml. There were no statistically significant differences in the hemodynamic measurements, arterial blood gas, and electrolyte variables when compared with the baseline values before the hemodilution (P > 0.05). The reaction time of TEG was longer 60 minutes after AEHH than before AEHH (P < 0.05); the other parameters of TEG had no differences when compared with the baseline values (P > 0.05).

CONCLUSION

The AEHH is safe and efficient in reduction of the perioperative homogenous blood transfusion in spine surgery.

Arginine vasopressin as a supplementary vasopressor in refractory hypertensive, hypervolemic, hemodilutional therapy in subarachnoid hemorrhage

INTRODUCTION

Hypertensive, hypervolemic, and hemodilutional (HHH) therapy for vasospasm in subarachnoid hemorrhage (SAH) refractory to phenylephrine requires high doses of catecholamines, leading to adverse adrenergic effects. Arginine vasopressin (AVP) has been shown to stabilize advanced shock states while facilitating reduction of catecholamine doses, but its use has never been reported in SAH. In this retrospective study, we investigated the hemodynamic effects and feasibility of supplementary AVP in refractory HHH therapy in SAH.

METHODS

Hemodynamic response (mean arterial pressure [MAP], heart rate, central venous pressure, cardiac index, systemic vascular resistance index, and end diastolic volume index) to a supplementary AVP infusion (0.01-0.04 IU/minute) was recorded within the first 24 hours in 22 patients. Secondary endpoints (serum sodium concentration, incidence of vasospasm, and intracranial pressure [ICP]) were compared to controls on HHH therapy with phenylephrine alone.

RESULTS

After initiation of AVP, MAP increased significantly compared to baseline. Phenylephrine doses decreased significantly, whereas other hemodynamic parameters remained stable. Serum sodium concentrations decreased similarly in both groups (-5 +/- 7 mmol/L versus -6 +/- 4 mmol/L; p = 0.25). No detrimental effects on vasospasm incidence or ICP and cerebral perfusion pressure were noted.

CONCLUSION

AVP may be considered as an alternative supplementary vasopressor in refractory HHH therapy with phenylephrine in SAH. Although we did not observe any deleterious effect of AVP on cerebral circulation, close observation for development of cerebral vasospasm should be undertaken, until it is clearly demonstrated that AVP has no adverse effects on regional cerebral blood flow and symptomatic cerebral vasospasm. Our limited data suggest that low-dose AVP does not cause brain edema, but further study is merited.

Modulation of perfusion and oxygenation by red blood cell oxygen affinity during acute anemia

Responses to exchange transfusion using red blood cells (RBCs) with modified hemoglobin (Hb) oxygen (O(2)) affinity were studied in the hamster window chamber model during acute anemia to determine its role on microvascular perfusion and tissue oxygenation. Allosteric effectors were introduced in the RBCs by electroporation. Inositol hexaphosphate (IHP) and 5-hydroxymethyl-2-furfural (5HMF) were used to decrease and increase Hb-O(2) affinity. In vitro P50s (partial pressure of O(2) at 50% Hb saturation) were modified to 10, 25, 45, and 50 mm Hg (normal P50 is 32 mm Hg). Allosteric effectors also decreased the Hill coefficient. Anemic condition was induced by isovolemic hemodilution exchanges using 6% dextran 70 kD to 18% hematocrit (Hct). Modified RBCs (at 18% Hct in 5% albumin solution) were infused by exchange transfusion of 35% of blood volume. Systemic parameters, microvascular perfusion, capillary perfusion (functional capillary density, FCD), and microvascular Po(2) levels were measured. RBcs with P50 of 45 mm Hg increased tissue Po(2) and decreased O(2) delivery (Do(2)) and extraction (Vo(2)) and RBCs with P50 of 60 mmHg reduced FCD, microvascular flow, tissue Po(2), Do(2) and Vo(2). Erythrocytes with increased Hb-O(2) affinity maintained hemodynamic conditions, Do(2) and decreased tissue Po(2). This study shows that in an anemic condition, maximal tissue Po(2) does not correspond to maximal Do(2) and Vo(2).

Effects of erythrocyte flexibility on microvascular perfusion and oxygenation during acute anemia

Responses to exchange transfusion using red blood cells (RBCs) with normal and reduced flexibility were studied in the hamster window chamber model during acute moderate isovolemic hemodilution to determine the role of RBC membrane stiffness in microvascular perfusion and tissue oxygenation. Erythrocyte stiffness was increased by 30-min incubation in 0.02% glutaraldehyde solution, and unreacted glutaraldehyde was completely removed. Filtration pressure through 5-μm pore size filters was used to quantify stiffness of the RBCs. Anemic conditions were induced by two isovolemic hemodilution steps using 6% 70-kDa dextran to a hematocrit (Hct) of 18% (moderate hemodilution). The protocol continued with an exchange transfusion to reduce native RBCs to 75% of baseline (11% Hct) with either fresh RBCs (RBC group) or reduced-flexibility RBCs (GRBC group) suspended in 5% albumin at 18% Hct; a plasma expander (6% 70-kDa dextran; Dex70 group) was used as control. Systemic parameters, microvascular perfusion, capillary perfusion [functional capillary density (FCD)], and oxygen levels across the microvascular network were measured by noninvasive methods. RBC deformability for GRBCs was significantly decreased compared with RBCs and moderate hemodilution conditions. The GRBC group had a greater mean arterial blood pressure (MAP) than the RBC and Dex70 groups. FCD was substantially higher for RBC (0.81 ± 0.07 of baseline) vs. GRBC (0.32 ± 0.10 of baseline) and Dex70 (0.38 ± 0.10 of baseline) groups. Microvascular tissue Po2 was significantly lower for Dex70 and GRBC vs. RBC groups and the moderate hemodilution condition. Results were attributed to decreased oxygen uploading in the lungs and obstruction of tissue capillaries by rigidified RBCs, indicating that the effects impairing RBC flexibility are magnified at the microvascular level, where perfusion and oxygenation may define transfusion outcome.

Bloodless (liver) surgery? The anesthetist's view

BACKGROUND/AIMS

An increasing amount of literature concerning blood conservation, restrictive transfusion strategies, pharmacological manipulation of the hemostatic and fibrinolytic systems, minimal invasive surgery, local hemostatic agents and guidelines for blood transfusion, is being published each year. Is 'bloodless (liver) surgery' or rather minimization of perioperative blood loss and transfusion requirement necessary?

METHODS

To answer this question, we studied key articles and checked cross-references with the support of PubMed and the Cochrane Database of systematic reviews.

RESULTS

At present there is still a need to reduce the use of blood. Pre-donation, set of transfusion triggers, (non-)pharmacological approaches to decrease surgical blood loss, hemodilution techniques, peri- and postoperative cell salvage and postoperative re-transfusion can contribute to the success of a bloodless (liver) surgery program.

CONCLUSION

We conclude that a multidisciplinary effort has to be made through the entire chain, from the outpatient clinic through discharge from the hospital, with the utmost exertion of all team members in which surgeons play a key role in the adaptation of a bloodless (liver) surgery program to the specific needs of patients.

A computational model of oxygen delivery by hemoglobin-based oxygen carriers in three-dimensional microvascular networks

A detailed computational model is developed to simulate oxygen transport from a three-dimensional (3D) microvascular network to the surrounding tissue in the presence of hemoglobin-based oxygen carriers. The model accounts for nonlinear O(2) consumption, myoglobin-facilitated diffusion and nonlinear oxyhemoglobin dissociation in the RBCs and plasma. It also includes a detailed description of intravascular resistance to O(2) transport and is capable of incorporating realistic 3D microvascular network geometries. Simulations in this study were performed using a computer-generated microvascular architecture that mimics morphometric parameters for the hamster cheek pouch retractor muscle. Theoretical results are presented next to corresponding experimental data. Phosphorescence quenching microscopy provided PO(2) measurements at the arteriolar and venular ends of capillaries in the hamster retractor muscle before and after isovolemic hemodilution with three different hemodilutents: a non-oxygen-carrying plasma expander and two hemoglobin solutions with different oxygen affinities. Sample results in a microvascular network show an enhancement of diffusive shunting between arterioles, venules and capillaries and a decrease in hemoglobin's effectiveness for tissue oxygenation when its affinity for O(2) is decreased. Model simulations suggest that microvascular network anatomy can affect the optimal hemoglobin affinity for reducing tissue hypoxia. O(2) transport simulations in realistic representations of microvascular networks should provide a theoretical framework for choosing optimal parameter values in the development of hemoglobin-based blood substitutes.

Acid-base and bio-energetics during balanced versus unbalanced normovolaemic haemodilution

Fluids balanced to avoid acid-base disturbances may be preferable to saline, which causes metabolic acidosis in high volume. We evaluated acid-base and bio-energetic effects of haemodilution with a crystalloid balanced on physical chemical principles, versus crystalloids causing metabolic acidosis or metabolic alkalosis. Anaesthetised, mechanically ventilated Sprague-Dawley rats (n=32, allocated to four groups) underwent six exchanges of 9 ml crystalloid for 3 ml blood. Exchange was with one of three crystalloids with strong ion difference (SID) values of 0, 24 (balanced) and 40 mEq/l. Controls did not undergo haemodilution. Mean haemoglobin concentration fell to approximately 50 g/l after haemodilution. With SID 24 mEq/l fluid, metabolic acid-base remained unchanged. Dilution with SID 0 mEq/l and 40 mEq/l fluids caused a progressive metabolic acidosis and alkalosis respectively. Standard base excess (SBE) and haemoglobin concentration were directly correlated in the SID 0 mEq/l group (R2 = 0.61), indirectly correlated in the SBE 40 mEq/l group (R2 = 0.48) and showed no correlation in the SID 24 mEq/l group (R2 = 0.003). There were no significant differences between final ileal values of CO2 gap, nucleotides concentration, energy charge, or luminal lactate concentration. SID 40 mEq/l crystalloid dilution caused a significant rise in subcutaneous lactate. In this group mean kidney ATP concentration was significantly less than controls and renal energy charge significantly lower than SID 0 mEq/l and control groups. We conclude that a crystalloid SID of 24 mEq/l provides balanced haemodilution. Bio-energetic perturbations with higher SID haemodilution may be more severe and need further investigation.

Interventions for branch retinal vein occlusion: an evidence-based systematic review

TOPIC

To assess the evidence on interventions to improve visual acuity (VA) and to treat macular edema and/or neovascularization secondary to branch retinal vein occlusion (BRVO).

CLINICAL RELEVANCE

Branch retinal vein occlusion is the second most common retinal vascular disease.

METHODS/LITERATURE REVIEWED

English and non-English articles were retrieved using a keyword search of Medline (1966 onwards), Embase, the Cochrane Collaboration, the National Institute of Health Clinical Trials Database, and the Association for Research in Vision and Ophthalmology Annual Meeting Abstract Database (2003-2005). This was supplemented by hand searching references of review articles. Two investigators independently identified all randomized clinical trials (RCTs) with more than 3 months' follow-up.

RESULTS

From 4332 citations retrieved, 12 RCTs were identified. There were 5 RCTs on laser photocoagulation. Grid macular laser photocoagulation was effective in improving VA in 1 large multicenter RCT, the Branch Vein Occlusion Study (BVOS), but 2 smaller RCTs found no significant difference. The BVOS showed that scatter retinal laser photocoagulation was effective in preventing neovascularization and vitreous hemorrhage in patients with neovascularization, but a subsequent RCT found no significant effect. Randomized clinical trials evaluating intravitreal steroids (n = 2), hemodilution (n = 3), ticlopidine (n = 1), and troxerutin (n = 1) showed limited or no benefit.

CONCLUSIONS

There is limited level I evidence for any interventions for BRVO. The BVOS showed that macular grid laser photocoagulation is an effective treatment for macular edema and improves vision in eyes with VA of 20/40 to 20/200, and that scatter laser photocoagulation can effectively treat neovascularization. The effectiveness of many new treatments is unsupported by current evidence.

Hemodilution Therapy With Hydroxyethyl Starch Solution (130/0.4) in Unilateral Idiopathic Sudden Sensorineural Hearing Loss

OBJECTIVE

Obtain and analyze first data on hydroxyethyl starch (HES 130/0.4) as monotherapy in acute idiopathic sudden sensorineural hearing loss (ISSNHL).

DESIGN

Randomized, double-blind, Phase-II, dose-finding study.

SETTING

Twenty-five ENT centers in Germany, the Czech Republic, Romania, and Austria.

PATIENTS

Two hundred and ten inpatients with first-time ISSNHL of at least 20 dB at two or more frequencies and 95 dB or less at all of the speech frequencies (0.5, 1.0, 2.0, 3.0, and 4.0 kHz) with respect to the other (normal) ear for up to 7 days (d).

INTERVENTION

Infusion of 750 mL/d with 45 (Group H), 30 (Group M), or 15 g/d HES (Group L), or glucose 5% (Group G) acting as "placebo" control during 6 days. MAIN ENDPOINT: Gain in average auditory threshold (in dB) from baseline to Day 7. RESULTS (MEDIANS): Average hearing loss at baseline was 24 dB, and infusions started 2 days after ISSNHL onset. No relevant group difference was observed in hearing gain or adverse treatment events, including pruritus. Half of all patients recovered completely by Day 7. SECONDARY ANALYSIS: In patients who started treatment within 2 days after the onset of symptoms and who had systolic blood'pressure (RRsyst) of less than 140 mm Hg, hearing at Day 90 had improved in all 28 cases under glucose 5%; for those who started treatment later and/or had RRsyst of 140 mm Hg or more, the risk for failing to recover under placebo was 29.2% (7/24). Comparing all 118 (51.9%) of 208 patients at such risk, outcome at Day 7 was markedly better in all HES subgroups than in the G'subgroup'(nH:nM:nL:nG = 32:29:32:24, Kruskal-Wallis, p = 0.0221).

CONCLUSION

All treatment groups were equivalent, including adverse treatment events. The secondary analysis showed that ISSNHL patients at risk for not improving under placebo (i.e., patients who started treatment more than 48 h after ISSNHL onset and/or with elevated RRsyst) recovered markedly better under infusions of HES 130/0.4.

Cardioprotective effects of acute normovolemic hemodilution in patients with severe aortic stenosis undergoing valve replacement

BACKGROUND

After acute normovolemic hemodilution (ANH), improvement of the rheologic conditions may contribute to optimize tissue oxygen delivery and attenuate ischemia-reperfusion injuries. It was hypothesized that ANH would confer additional cardioprotection in patients with ventricular hypertrophy undergoing open heart surgery.

STUDY DESIGN AND METHODS

This study was a randomized controlled trial. Forty patients scheduled for elective aortic valve replacement were randomly assigned to a control group (standard care) or an ANH group (target hematocrit level of 28%). All patients were managed with standard myocardial preservation techniques (cold blood cardioplegia, anesthetic preconditioning). The outcome measures included the release of myocardial enzymes, perioperative hemodynamic changes, the need for pharmacologic cardiovascular support, and cardiac complications.

RESULTS

In the ANH group, the postoperative release of troponin I (mean peak plasma concentrations, 1.7 ng/mL; 95% confidence interval, 1.4-2.1 ng/mL) and myocardial fraction of creatine kinase (22 U/L; range, 18-24 U/L) was significantly lower than in the control group (3.6 [range, 3.0-4.2] ng/mL and 45 [range, 39-51] U/L, respectively). In addition, requirement for inotropic support was significantly lower and fewer hemodiluted patients presented adverse cardiac events. After ANH, there was a significant decrease in heart rate (-11 +/- 6%) and rate-pressure product (-16 +/- 8%) until the aortic cross-clamping time and, at the end of surgery, the circulating levels of erythropoietin (EPO) were higher than in control patients (13.6 +/- 4.2 mUI/mL vs. 7.3 +/- 2.4 mUI/mL; p < 0.05).

CONCLUSIONS

Besides conventional cardiac preservation techniques, preoperative ANH further attenuates myocardial injuries. Optimization of preischemic myocardial oxygen delivery and/or consumption and the postconditioning effects of endogenous EPO are potential mechanisms for ANH-induced cardioprotection.

Hydroxyethyl starch is superior to lactated Ringer as a replacement fluid in a pig model of acute normovolaemic haemodilution

BACKGROUND

Tissue tolerance to oxygen privation during acute normovolaemic haemodilution with different fluids remains unclear. We tested the hypothesis that hydroxyethyl starch (HES) is superior to lactated Ringer's solution in pigs for preserving tissue perfusion during acute normovolaemic haemodilution.

METHODS

Twenty-four animals were randomized into control, lactated Ringer's solution and HES groups. All groups, except the control, underwent acute normovolaemic haemodilution. Haemodynamics, oxygen parameter indices, global anaerobic metabolic markers, echocardiographic parameters, gastric tonometry and serum osmolarity were monitored at baseline, immediately after (0 min) and 60 and 120 min after the end of haemodilution. Myocardial, liver, stomach and intestine samples were collected for further evaluation.

RESULTS

Cardiac and oxygen parameter index responses to acute normovolaemic haemodilution were comparable. However, the increment in cardiac index, stroke volume index, and left ventricular stroke work index were more sustained in the starch group. In the lactated Ringer's group, gastric pH decreased significantly and was accompanied by a significant increase in lactate. Myocardial ultrastructure was better preserved in the starch group. The other tissue samples presented no change.

CONCLUSIONS

In this model of ANH, the starch group had a superior haemodynamic response. Minor loss of myocardial cellular integrity and preserved gastric pHi reinforce these findings.

Comparison of Hemodynamic Changes After Acute Normovolemic Hemodilution Using Ringer’s Lactate Versus 5% Albumin in Patients on β-Blockers Undergoing Coronary Artery Bypass Surgery

OBJECTIVE

Acute normovolemic hemodilution (ANH) is used cautiously in coronary artery disease (CAD) patients because of concerns of compromised coronary blood flow. This study aimed to compare hemodynamic changes by using either Ringer's lactate or albumin for ANH in CAD patients receiving beta-blockers.

DESIGN

Prospective, randomized study.

SETTING

Postgraduate teaching hospital.

PARTICIPANTS

Thirty patients undergoing coronary artery bypass graft surgery (CABG) (hemoglobin >12 g/dL, on chronic beta-blocker therapy).

INTERVENTIONS

Monitoring, induction, and anesthesia followed a routine protocol for CABG surgery including pulmonary artery catheter placement. Patients were randomly included in group 1 (ANH by Ringer's lactate) or in group 2 (ANH by 5% albumin). A hemodynamic calculation software program was used for parameters recorded before and after ANH.

MEASUREMENTS AND MAIN RESULTS

ANH could not be completed in 5 patients (33%) in group 1 because of a fall in mean arterial pressure (MAP) of more than 25% from baseline. In both groups posthemodilution MAP, heart rate, systemic vascular resistance, and oxygen delivery index decreased, whereas stroke volume index, cardiac index, and tissue oxygen extraction increased significantly as compared to baseline values (p < 0.05). Hemodynamic parameters were better maintained during the study period in group 2 than group 1.

CONCLUSIONS

Hemodynamic stability was better maintained by 5% albumin than Ringer's lactate for ANH in chronic beta-blocked CAD patients. Despite an increase in cardiac index, systemic oxygen delivery was decreased irrespective of the hemodiluting fluid used. ANH to a hemoglobin value of 10 g/dL in chronically beta-blocked CAD patients was well tolerated.

[Acute normovolemic hemodilutlon: advantages and limitations]

Although arterial oxygen content is decreased after acute normovolemic hemodilution (ANH), blood rheology is improved and cardiac output is increased through increased venous return. To meet metabolic demand, tissue oxygen extraction is increased and the sympathetic nervous system is activated only in awake subjects. In man, hemoglobin levels of < 40-50 g/L may induce anaerobic cell metabolism. The transfusion threshold should take into account the individual patient metabolic needs and the associated cardio-pulmonary diseases. Better tissue blood flow distribution and erythropoietin liberation resulting from ANH may potentially attenuate myocardial ischemic injuries. ANH is poorly effective in reducing the necessity of allogenic blood transfusion, especially in centres where a restrictive transfusion policy is already implemented.

[Major surgery on Jehovah's Witnesses]

BACKGROUND

Jehovah's Witnesses refuse transfusions of the main blood components. This challenges the safety of performing major surgical procedures. At the Norwegian Radium Hospital, we have taken the views of Jehovah's Witnesses regarding blood transfusions into account when planning major surgical procedures and perform these without such transfusions. We present a case and our experiences and routines when performing major cancer surgery on Jehovah's Witness patients.

MATERIAL AND METHODS

The medical records of Jehovah's Witnesses, who underwent major surgery at the Norwegian Radium Hospital from April 1992 to February 2006, were surveyed retrospectively. Based on relevant literature, our routines and methods are discussed along with some legal and ethical aspects.

RESULTS AND INTERPRETATION

Major transfusion-free surgery can be performed successfully on Jehovah's Witnesses. This requires advanced planning, good routines and close collaborative team efforts. The most relevant techniques to make major surgery feasible are preoperative optimalisation of the haemoglobin levels and acute normovolemic haemodilution and the use of cell saver under surgery.