A new nomogram facilitating adequate haemodilution

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.

Ivory Osteoma of the Craniofacial Skeleton

The authors describe the clinical presentation, investigation, and surgical management of two cases of benign ivory osteoma of the craniofacial skeleton. In the first case, a bony mass located over the frontal region had become a cosmetic burden to the patient, and she requested removal with minimal morbidity. Accordingly, an endoscopic procedure, with minimal access incisions located behind the hairline, was devised. In the second case, the patient, a Jehovah's Witness, presented with a long history of slowly enlarging bony masses over the maxilla and in the pterygopalatine space. She finally requested surgical intervention when the symptoms of pain related to fifth nerve compression at the foramen ovale became intolerable. Key aspects of the preoperative and perioperative management strategies used to avoid blood transfusion are detailed, as is the surgical approach, which included a bicoronal scalp flap with temporary removal of the zygomatic arch and the coronoid process. Finally, the etiology, histology, and natural history of ivory osteomas are discussed.

Perioperative hemodilution

Acute normovolemic hemodilution (ANH) entails the removal of blood from a patient either immediately before or shortly after induction of anesthesia and the simultaneous replacement with cell-free fluid, preferably synthetic colloids with a predictable volume effect (6% dextran 60/70, 6% hydroxyethyl starch 200,000 and 130.000, respectively). Hemodilution is part of the concept for avoiding or limiting the use of allogeneic blood and should be considered for patients undergoing elective surgery free of contraindications and presenting with an initial hemoglobin concentration > or = 12 g/dl and an anticipated blood loss of > or = 1500 ml. The efficacy of ANH, judged by the necessity to transfuse homologous blood, depends on the preoperative (initial) hematocrit, the target hematocrit (to which hemodilution is performed), and the preset intra- and postoperative transfusion trigger. In the past data from clinical trials have shown that in healthy subjects a target hematocrit of 20-25% (7.0-8.0 g/dl hemoglobin concentration) is feasible and safe for the patient. The lower the target hemoglobin concentration, the more extensive monitoring is required: intraoperative target hemoglobin concentrations of 5.0 g/dl and less have been tolerated by young surgical patients without adverse effects. The safety as well as efficacy of acute normovolemic hemodilution in terms of reducing homologous blood transfusion requirements have been demonstrated in various clinical studies. ANH therefore is regarded an integral part of programs aimed at reducing the need for homologous blood, and can thus be successfully combined with preoperative autologous blood deposition, intraoperative blood salvage and carefully adjusted surgical techniques.

Dextran 70 and blood loss during transurethral resection of the prostate

BACKGROUND

Dextran is an effective plasma expander but also a potential anticoagulant. This article attempts to establish the clinical significance of any increased intra-operative blood loss associated with the use of dextran 70 during transurethral resection of the prostate (TURP).

METHODS

The blood loss was measured in used irrigating fluid by a photometer in 800 patients undergoing TURP. In 154 of them, 500-1,000 ml of 6% dextran 70 was given for volume replacement. A regression model was used to test for interactions between the use of dextran and the operative parameters that correlated independently with the blood loss.

RESULTS

The bleeding varied between 10 and 3,825 ml (median 323). Operative parameters correlating to the blood loss were: weight of the prostatic resectate, operating time, irrigating fluid absorption, and systolic arterial blood pressure. The result of this regression analysis indicated that dextran did not increase the blood loss. Neither did the prostatic weight and operating-time-corrected blood loss increase when dextran was infused.

CONCLUSION

There was no indication that dextran 70 given within the recommended dose range increases the blood loss during TURP.

Systemic haemodynamics and oxygenation during haemodilution in children

Transfusion of homologous blood should be avoided when possible, and one technique that diminishes perioperative requirement for donor blood is haemodilution. In children its effects on systemic haemodynamics and systemic oxygenation have not been reported. Six children aged 4-12 yr were anaesthetised for major surgery and blood was withdrawn to reduce packed cell volume to 25%. Cardiac index increased from 3.1 (SD 0.5) L min-1 m-2 at baseline to 4.4 (0.5) L min-1 m-2 at the end of surgery, when packed cell volume was 16 (1)%; this change, compensating for the decline in oxygen carrying capacity, was associated with a fall in systemic vascular resistance and a rise in stroke volume. Oxygen extraction from haemoglobin rose from 0.22 (0.05) to 0.33 (0.06). Perioperative blood loss was 40% of circulating blood volume; however, owing to reinfusion of autologous blood (and use of a cell saver in three patients), the haemoglobin one day after operation was only 19% lower than preoperatively (9.9 [1.5] vs 12.5 [2.5] g/dL). In this study, children seemed at least as able as adults to compensate for the effects of haemodilution, which allowed major surgery without transfusion of homologous blood.

Acute isovolaemic haemodilution: the best option for autologous blood transfusion in Africa?

The purpose of this study was to identify the best method of autologous blood transfusion to be applied in an East African hospital. One hundred and nine consecutive patients for whom major blood loss was anticipated were enrolled. Seventeen patients donated 1 unit of blood 3 days preoperatively and 92 underwent acute isovolaemic haemodilution prior to induction of anaesthesia. For the haemodiluted patients a 2:1 ratio of sterile pryogen-free saline to collected blood was used. One of the 16 patients from whom 2 units were withdrawn by haemodilution experienced hypovolaemia which was rapidly restored by additional transfusion of colloid. Of the patients who donated blood preoperatively only 23.5% were autotransfused compared to 98.9% of the haemodiluted patients. Of the latter 23.9% (22) had an intraoperative blood loss exceeding 15% of their total blood volume and 7.6% (7) lost more than 25%. Only one received homologous blood in addition. For hospitals with limited blood bank facilities and regular cancellation of surgery, the use of acute isovolaemic haemodilution is recommended. A 3:1 ratio of saline to blood is now advised when 1 unit is withdrawn and a part replacement with crystalloid when 2 units are collected.

Glutamine and alpha-ketoglutarate prevent the decrease in muscle free glutamine concentration and influence protein synthesis after total hip replacement

After surgical trauma, protein synthesis, as well as the concentration of free glutamine in muscle, decreases. Total parenteral nutrition (TPN) alone does not prevent the decrease of glutamine in muscle, but TPN supplemented with glutamine or its precursor, alpha-ketoglutarate, maintains amino acid concentration in muscle and preserves protein synthesis. The aim of this study was to characterize a human trauma model using patients undergoing total hip replacement, and furthermore to investigate whether glutamine or alpha-ketoglutarate alone without TPN can prevent the postoperative decrease in muscle free glutamine. Metabolically healthy patients undergoing total hip replacement were randomized into three groups. The control group (n = 13) received glucose 2 g/kg body weight (BW) during surgery and the first 24 postoperative hours. The glutamine group (n = 10) received glucose 2 g/kg BW and glutamine 0.28 g/kg BW, and the alpha-ketoglutarate group (n = 10) received glucose 2 g/kg BW and alpha-ketoglutarate 0.28 g/kg BW. Muscle biopsies were performed before surgery and 24 hours postoperatively. Free glutamine concentration in muscle decreased from 11.62 +/- 0.67 to 9.80 +/- 0.36 mmol/kg wet weight in the control group (P < .01), whereas it remained unchanged in both the glutamine group and alpha-ketoglutarate group. Protein synthesis, as reflected by the concentration of total ribosomes, decreased significantly in the control group, but not in glutamine and alpha-ketoglutarate groups. Polyribosome concentration decreased significantly in both the control and alpha-ketoglutarate groups. Total hip replacement can be used as a reproducible trauma model, with characteristic changes in the muscle amino acid pattern and protein synthesis 24 hours postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Desmopressin acetate does not reduce blood loss during total hip replacement in patients receiving dextran

The blood loss-reducing effect of desmopressin during dextran therapy was studied in a double-blind fashion in 79 elderly but otherwise healthy patients with preoperative normal bleeding time undergoing total hip replacement for primary coxarthrosis. An infusion of desmopressin (0.3 microgram/kg body weight) or placebo was randomly administered immediately after administration of spinal anaesthesia and six hours later. Haemostasis was evaluated on the basis of vWF: ristocetin cofactor activity, FVIII: C activity, human tissue plasminogen activator (tPA) plasminogen activator inhibitor type (PAI), beta-thromboglobuline (beta TG) and a clot impedance test (Sonoclot). There were no statistically significant differences (P > 0.05) in mean blood loss or transfusion requirements between the placebo and the desmopressin group. There was a significantly increase (P < 0.01) both in vWF: ristocetin cofactor and in FVIII: C activity after both infusions of desmopressin compared with placebo. There was no significant difference in beta TG, tPA, PAI or Sonoclot analysis between the groups. In conclusion, desmopressin did not reduce blood loss in patients undergoing total hip replacement.

Intraoperative hemodilution and autologous platelet rich plasma collection: two techniques for collecting fresh autologous blood

Intraoperative hemodilution (IH) and autologous platelet rich plasma (APRP) collection are two techniques used to obtain autologous blood in the operating room. They have been used to reduce allogeneic blood exposure in patients undergoing both cardiac and non-cardiac surgery. Both components have the advantage of providing fresh blood not subject to the storage lesion. Whole blood (IH) or platelet rich plasma is removed from the patient as anesthesia is induced and replaced with acellular fluid. The blood is transfused back after bypass or major bleeding has ceased. Although used commonly, the data supporting the use of either technique are controversial. Methodologic problems which have confounded studies evaluating their utility include: poorly defined transfusion criteria, concommitant use of other blood conservation techniques (i.e. cell salvage, pharmacologic agents, hypothermia, controlled hypotension) and changing transfusion practices with greater tolerance of normovolemic anemia. Randomized controlled studies with well defined up to date transfusion criteria are needed to identify patients likely to benefit from these techniques.

A simple method for calculating component dilution during fluid resuscitation: the Leuven approach

STUDY OBJECTIVES

To test the reliability of the Leuven approach, a balance between oversimplified empiric rules and more complex calculations requiring the use of nomograms or computers, to determine blood component dilution during large transfusions. To present schemes for blood component dilution and stabilization, as well as four examples showing the practicability of the method.

DESIGN

Prospective study.

SETTING

Orthopedic operating rooms at a university hospital.

PATIENTS

108 patients undergoing total hip replacement with expected large blood loss.

INTERVENTIONS

Component concentrations were measured after patient arrival in the recovery room. Blood loss was followed clinically.

MEASUREMENTS AND MAIN RESULTS

Preset target component concentrations [hematocrit (Hct) 31%; total serum protein (TSP) 5.0 g/dl; prothrombin time (PT) 50%; blood platelets (BLPL) 50,000/microliters)] were compared with concentrations measured on arrival in recovery after dilution and stabilization, according to the transfusion scheme. Average blood loss was 3,226 +/- 1,600 ml (mean +/- SD). End component concentrations were Hct, 33.4% +/- 3.3%; TSP, 5.2 +/- 0.5 g/dl; PT, 52% +/- 12%; BLPL, 97,000/microliters. Hct and TSP showed significant (p < 0.05) but clinically unimportant differences from target concentrations. Possible reasons for variability in end concentrations are discussed.

CONCLUSION

The Leuven approach produces reliable blood component concentrations after extensive transfusions. It allows the clinician to decide for himself or herself, in accordance with general consensus and the patient's individual needs, when to stabilize blood components.

Cardiovascular effects of moderate normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia in man

The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction of anaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group (H) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/05. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 +/- 7.9 to 39.3 +/- 7.1 ml.M-2 and from 73.8 +/- 20.3 to 94.9 +/- 18.5 ml.M-2 respectively (mean +/- s.d., both P < 0.05). However, heart rate decreased so that cardiac index did not change. O2 delivery decreased significantly (from 389 +/- 70 to 311 +/- 63 ml.min-1.m-2; P < 0.05), but was not different to the control group. O2 consumption was maintained by an increase in O2 extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that O2 delivery was similar in the two groups. O2 consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

Acute normovolaemic haemodilution and idiopathic scoliosis surgery: effects on homologous blood requirements

After the introduction of acute normovolaemic haemodilution(NVHD) in our hospital, we prospectively studied 19 patients managed with moderate NVHD (mean haematocrit 0.28, SD 0.02) during idiopathic scoliosis surgery (mean angle 53.2, SD 16.7 degrees) with the Cotrel-Dubousset instrumentation (CDI). Our standard scoliosis anaesthetic technique was used. Intraoperatively, one patient received one unit of homologous blood. Postoperatively, seven patients received ten units of homologous blood. Homologous blood used was reduced by about 83% for this procedure in our institution. In the assessment of fluid and blood requirements we found physical signs reflecting tissue perfusion and oxygen supply more reliable than the estimated blood loss using the suction bottle and swabs. The similar postoperative complications (nine fever, five atelectasis/pneumonia, one urinary infection, one phlebitis), anaesthetic duration (mean 5.21, SD 1.13) hours, hospitalisation (mean 6.67, SD 1.19) days and return to normal activity (mean 8, SD 7.68) weeks indicate that the NVHD patients did just as well as with our previous regimen when only homologous blood was used.

Isovolemic hemodilution with dextran 60 as treatment of pancreatic ischemia in acute pancreatitis. Clinical practicability of an experimental concept

OBJECTIVE

This phase-I study transferred the concept of isovolemic hemodilution, which has been proven beneficial in the treatment of experimental acute pancreatitis to the patient.

SUMMARY BACKGROUND DATA

Pancreatic ischemia represents one main mechanism in the pathogenesis of necrotizing pancreatitis. Isovolemic hemodilution with dextran 60 has been shown experimentally to limit the progression of pancreatic necrosis by improving pancreatic microcirculation.

METHODS

Thirteen patients with clinically severe nonbiliary pancreatitis and CT-classification E according to Balthazar were enrolled. Exclusion criteria were anemia, coronary heart disease, chronic obstructive pulmonary disease, coagulopathies, and secondary referral. The volume of blood to be exchanged for dextran 60 was calculated from a nomogram based on body surface. Isovolemic hemodilution aimed at a hematocrit of 30%. Independent from the exchange procedure conventional fluid resuscitation was performed to adjust the central venous pressure at 6 +/- 2 mm Hg.

RESULTS

Whole blood (750-1,700 mL) was exchanged for dextran 60 during 45 to 70 minutes. No adverse effect was encountered; central hemodynamics were not affected. Considering a mean Ranson score of 5, mortality was low (7.7%). Progression of pancreatic necrosis was registered in only two patients subsequently undergoing surgical treatment (15%).

CONCLUSIONS

Isovolemic hemodilution is practicable in patients. A randomized trial has to prove whether isovolemic hemodilution can substantially alter the course of acute pancreatitis as anticipated from animal studies.

[Normovolemic hemodilution]

Transfusion of homologous blood to surgical patients is not without risks. Thus, strategies to prevent blood loss must be considered. This article deals with one of them: normovolaemic haemodilution together with its advantages, physiological consequences and technical aspects. In particular, it is important to follow certain inclusion criteria. The technique is safe, effective and relatively easy to implement. In the future, it could be used in non-surgical patients, when it is necessary to increase tissue perfusion.

Acute hypervolaemic haemodilution to avoid blood transfusion during major surgery

16 patients underwent acute hypervolaemic haemodilution with dextran 40 and Ringers lactate, to see whether this procedure could avoid preoperative blood transfusion. Packed cell volume (PCV) and oxygen extraction decreased, and cardiac index and pulmonary wedge pressure increased, although end-systolic area was unchanged. PCV was not significantly different between patients who lost less than or greater than 20% of their initial blood volume. This preoperative manoeuvre, which reduces loss of red blood cells, allowed major surgery to be completed safely without blood transfusion.

Pancreatic ischaemia in experimental acute pancreatitis: mechanism, significance and therapy

Much clinical and experimental evidence suggests that pancreatic ischaemia in the early phase of acute pancreatitis is important in the development of pancreatic necrosis. While depletion of intravascular volume has often been assumed to be the main circulatory defect, an additional disturbance of pancreatic microcirculation has been demonstrated experimentally. Possible contributory mechanisms include chemical-induced vasoconstriction, direct injury of vessel wall, intravascular coagulation and increased endothelial permeability resulting in pancreatic oedema, haemoconcentration and impaired venous drainage. Pancreatic ischaemia as a consequence of these local effects seems to be responsible for the transition of mild pancreatitis to parenchymal necrosis. In experimental models the beneficial effect of various drugs and of sympathetic blockade has been ascribed to an improvement in pancreatic perfusion. Although effective volume therapy is generally accepted as the mainstay of conservative treatment in acute pancreatitis, the efficacy of different fluid preparations is still controversial, and simple fluid resuscitation has not been shown to prevent the development of parenchymal necrosis. The specific impairment of pancreatic microcirculation cannot be prevented merely by replenishment of intravascular volume with crystalloids, albumin or plasma despite normalization of macrohaemodynamics. In contrast, partial replacement of blood by dextran preparations has been shown to increase pancreatic perfusion by improving blood fluidity. Isovolaemic haemodilution in conjunction with conventional fluid therapy may provide a new and effective means of protecting the pancreas from secondary injury due to the early ischaemic phase of acute pancreatitis.

Estimating allowable blood loss with correction for variations in blood volume

All the theoretical relationships between blood loss and change in haematocrit used for calculating the allowable pre-transfusion blood loss assume a strictly normovolaemic situation. In this study a formula was derived in which account was taken of the variation in blood volume. The formula was based on clinical data. Measurements of the blood loss, the blood haemoglobin concentration and the haematocrit (HCT) were performed on 230 occasions in the course of 35 transurethral prostatic resections. The change in blood volume was estimated by the haemoglobin dilution method and the value so obtained was compared to both the measured haematocrit and the theoretical value that would presumably have been recorded if there had been no change in blood volume. The relationship established from these comparisons was: blood loss = preoperative blood volume x [In preop HCT - In postop HCT (1 + 0.15 x blood volume change)].

Hemodilution--possibilities and safety aspects

Normovolemic hemodilution is an essential part of the overall strategy to avoid exposure of patients to the hazards of homologous blood transfusions. It includes beneficial effects on the flow properties and flow conditions of blood. A hematocrit of 30% can be regarded as an optimal compromise between the fluidity and the oxygen content of the blood. Compensatory responses such as increased cardiac output and stroke volume occur following hemodilution. In patients with compromised coronary reserve the degree of hemodilution that is tolerated has to be carefully considered. Therefore specific selection criteria for patients to be preoperatively hemodiluted are needed. For reasons of safety, efficiency and practicability colloid solutions rather than crystalloid solutions should be used for intentional hemodilution.

Preoperative haemodilution

In preoperative haemodilution, blood is withdrawn before surgery while normovolaemia is maintained by infusion of cell free fluid. A surgical bleeding then entails a smaller loss of red cells. Reinfusion of the saved blood maintains normovolaemia, raises hematocrit and decreases the need for donor blood. Dilutional anaemia may endanger the oxygenation of the tissues. Tissue oxygenation can be upheld by an augmented and redistributed cardiac output and by a raised oxygen extraction. These compensatory mechanisms are less efficient in the presence of vascular stenosis, in particular in the myocardium which relies virtually exclusively on coronary vasodilatation. Major contraindications to preoperative haemodilution are, apart from coronary insufficiency, ventricular failure and valvular disease. Deleterious increases in cardiac oxygen consumption and/or heart rate may result from e.g. hypovolaemia, arterial desaturation and painful stimuli. The haemodilution procedure requires knowledge and vigilance in all involved personnel and gives best results if combined with other blood saving measures, like blood predeposit and intraoperative red blood cell salvage.

[Calculation of the blood volume to be removed for intentional normovolemic hemodilution]

Intentional haemodilution is more and more frequently used. Although it is a simple technique, it can only be carried out with a maximum of safety if the operator has an idea of the amount of blood that needs to be removed to obtain the required haematocrit value. Several methods have been suggested, using more or less complex calculations, or nomogrammes. A new simple rule is presented here which gives an estimation of the amount of blood to be removed in three steps: 1) the theoretical total blood volume (VS), according to weight, height and sex of the patient, 2) the ratio (R) between the initial and required final haematocrit, and 3) the volume of blood to be removed (Vp) according to VS and R. A mono-compartment model with identical inflow and outflow was used. A multicentre trial with 229 haemodilutions showed that the volume removed (mean = 1,325 ml; SD = 642 ml) was 15% less than the calculated volume (mean = 1,526 ml; SD = 561 ml). No one factor was found to explain this difference. The haematocrit values obtained by microcentrifuge were compared with those obtained by a laboratory automatic counter. The mean of the differences was 0.002 (SD = 0.029). Because of the possible errors involved in estimating the total blood volume and the haematocrit before dilution, it is essential that the haematocrit be checked at least once during the haemodilution.