[Prolonged normovolemic hemodilution in therapy of patients with obliterating endarteritis of lower limb vessels]

The response to prolonged normovolemic hemodilution in 101 patients with obliterating endarteritis of the legs manifested as pain relief in 84.2%, complete or partial healing of trophic ulcers in 82.9 and 17% of cases, respectively, remission from stage III to stage II, from stage II to stage I in 47% and 37.3% of patients, respectively. There was also less frequent occurrence of postoperative specific and nonspecific complications, of high-traumatic amputations.

[Do corticotherapy and hemodilution decrease postoperative inflammation after maxillofacial surgery?]

OBJECTIVE

To assess the efficiency of corticosteroids and preoperative acute normovolaemic haemodilution (PANHD) in reducing postoperative inflammation after maxillofacial surgery.

STUDY DESIGN

Randomized clinical trial.

PATIENTS

Thirty-two patients scheduled to undergo maxillary osteotomy for facial dysmorphia were randomized into four groups of eight (PANHD or not; corticosteroids or not).

METHODS

PANHD decreased haematocrit to 30%. In the corticosteroid groups, methylprednisolone 1.5 mg.kg-1 was given intravenously at the beginning of surgery (after PANHD in haemodiluted group), and after surgery, 1.5 mg.kg-1 iv daily for three days. Postoperative inflammation was assessed with an X-Ray technique (radiotelemetry) providing data on tissue thickness (extent of facial oedema), and by measurement of plasma concentrations of four acute phase proteins during the first postoperative week.

RESULTS

No change in facial oedema and in acute phase proteins occurred with PANHD. Corticosteroids decreased postoperative oedema and acute phase proteins.

CONCLUSION

Corticosteroids decrease postoperative inflammation after maxillofacial surgery but not PANHD.

Observations on isovolemic hemodilution in acute ischemic stroke

The reduction of blood viscosity is an alternative of the improvement of the cerebral flow during an acute ischemic stroke (AIS). We studied 18 patients with AIS, ranging in age from 44 to 72 years (mean age 57 years), 11 females and 7 males. We applied an isovolemic hemodilution for 2 days starting with an emission of 250 or 500 ml blood, followed by the infusion of an equal amount of 6% HAES-steryl solution. We made determination of hematocrit, plasma density, plasma viscosity 1, 3 and 6 hours before and after the infusion; a decrease was noted in all the studied hemorheologic parameters, and the short term clinical course was an improvement. In conclusion, the isovolemic hemodilution using 6% HAES solution reduced hematocrit, plasma density, plasma viscosity but no changes were noted in the hemodynamic parameters; isovolemic hemodilution as the single therapeutic method in AIS does not solve the therapy, involving only one pathogenetic link, i.e., the microcirculation.

[Preoperative hemodilution by erythrocytapheresis with homologous blood saving in total hip arthroplasty]

OBJECTIVES

To compare three techniques for decreasing homologous blood requirements in total hip arthroplasty (THA), including preoperative autologous donation (PAD), preoperative acute normovolaemic haemodilution with erythrocytapheresis (erythro) and intraoperative normovolaemic haemodilution (haemo).

STUDY DESIGN

Prospective clinical trial.

PATIENTS

The study included 45 patients scheduled for THA, under general anaesthesia and operated on by the same surgeon. The patients were allocated into three groups of 15 each.

METHODS

Blood loss was assessed, during surgical procedure, by the weight of sponges and, the amount of blood collected in the suction bottles during and after surgery. The haemoglobin concentration was measured at the time of preoperative assessement (d-30), just prior to surgery (d-1), in the recovery room (d+3h), and 1, 3, and 8 days later (d8). The transfusion end-point in the three groups was to obtain a haemoglobin concentration of 100 g.L-1 from d+3h until d8. Every pack of red blood cells transfused was weighed and its haematocrit assessed to determine the accurate volume of red blood cells.

RESULTS

In the three groups haemoglobin concentration was similar from d+3h until d8. In the PAD group, no patient required homologous blood transfusion. There was no significant difference between the two other groups in the mean volume of homologous red blood cells required (308 +/- 197 mL in erythro group and 331 +/- 202 mL in the haemo group, respectively). The intraoperative blood loss was significantly higher (P = 0.001) in the erythro group: 914 +/- 305 mL vs 665 +/- 263 in the PAD group and 512 +/- 146 mL in the haemo group, respectively. There was an inverse correlation between haematocrit at d-1 and intraoperative bleeding (r = -0.7) (P = 0.0001). The distribution of the points was fitted as an exponential curve.

CONCLUSIONS

In THA, PAD is obviously the best technique to avoid homologous blood transfusion. However, when PAD is not feasible, removal of blood prior to surgery does not decrease requirements of homologous blood, as intraoperative blood loss is higher. Our results strongly question the use of major haemodilution during a surgical procedure exposing a major blood loss.

[Indications and role of albumin for vascular loading in trauma patients and during preoperative period]

The use of albumin solutions for volume replacement remains controversial. The last American guidelines recommend the use of albumin for resuscitation in case of a contra-indication of artificial colloids or the requirement of sodium restriction. Recent trials did not show any beneficial effect of albumin on the mortality and morbidity rates. Only an improvement of the rheologic conditions has been found with albumin (and dextran 40), in comparison with starch and gelatin. On the basis of cost-effectiveness considerations, artificial colloids should be at this time favoured over albumin for intravascular expansion, except in pregnant women. For resuscitation, albumin could be used when the recommended upper limit of hydroxyethyl starch vol-ume has been reached and fresh frozen plasma not yet required. During preoperative haemodilution, low molecular weight hydroxyethyl starch has at least the same efficacy as albumin. When a rheological effect is required, albumin could be used.

A pilot study of the effects of a perflubron emulsion, AF 0104, on mixed venous oxygen tension in anesthetized surgical patients

A pilot study of a perfluorochemical (PFC) emulsion was undertaken to determine whether administration of a perflubron emulsion could result in measurable changes in mixed venous oxygen tension. Seven adult surgical patients received a 0.9-g PFC/kg intravenous dose of perflubron emulsion after acute normovolemic hemodilution (ANH). Hemodynamic and oxygen transport data were collected before and after ANH, immediately after PFC infusion, and at approximate 15-min intervals throughout the surgical period. There were no clinically significant hemodynamic changes associated with the administration of the PFC emulsion. There was a significant increase in mixed venous oxygen tension (PVO2) after the PFC infusion, while cardiac output and oxygen consumption were unchanged. As surgery progressed, the hemoglobin concentration decreased with ongoing blood loss while PVO2 values remained at or above predosing levels. Peak perflubron blood levels were 0.8 g/dL immediately postinfusion, and approximately 0.3 g/dL at 1 h. This pilot study demonstrates that administration of perflubron emulsion results in measurable changes in mixed venous oxygen tension during intraoperative ANH.

[Isovolemic hemodilution in coronary heart disease--clinical and hemodynamic effects]

Clinical and hemodynamic effects of isovolemic hemodilution (HD) were evaluated in 12 patients (aged 59 +/- 8 years) with severe multivessel coronary artery disease (CAD) and angina pectoris grade III (Canadian Cardiovascular Society classification) despite high-dose medical treatment. In none of these patients was aortocoronary bypass grafting or percutaneous transluminal coronary angioplasty possible. Prior to HD and after 3 months of HD the incidence of angina pectoris was determined by means of questionnaires; hemodynamic measurements were performed with right heart catheterization at rest and during exercise. After 3 months of HD hematocrit was reduced from 46.2 +/- 1.3% to 38.5 +/- 0.5%. The weekly incidence of angina pectoris was unchanged (19 +/- 7 before, 17 +/- 8 after HD). Cardiac index was 2.5 +/- 0.7 1/min/m2 at rest and 3.9 +/- 1.0 1/min/m2 during exercise before, 2.6 +/- 0.5 1/min/m2 at rest and 3.9 +/- 0.8 1/min/m2 during exercise after HD. Stroke volume index did not increase significantly neither at rest nor during exercise after HD. Initially, systemic vascular resistance decreased from 1659 +/- 603 to 1398 +/- 420 dyns/cm5 during exercise; after HD it was 1522 +/- 551 (rest) and 1283 +/- 348 dyns/cm5 (exercise). Mean pulmonary artery pressure (PAP) and wedge pressure (WP) were unchanged at rest (PAP: 19.9 +/- 6.7 mm Hg before, 19.2 +/- 6.5 mm Hg after HD; WP: 10.8 +/- 5.5 mm Hg before, 10.7 +/- 4.3 mm Hg after HD) and during exercise (PAP: 43.0 +/- 9.9 mm Hg before, 42.8 +/- 8.9 mm Hg after HD; WP: 30.8 +/- 4.6 mm Hg before, 30.6 +/- 6.5 mm Hg after HD). In conclusion, in patients with CAD isovolemic HD does not reduce angina pectoris but also does not induce clinical deterioration. Furthermore, isovolemic HD does not worsen the hemodynamic effects of severe CAD with impaired left ventricular function.

[Experience in using prolonged normovolemic hemodilution in patients with diabetic angiopathies of the vessels of the lower extremities]

Prolonged normovolemic hemodilution (PNH) was shown to be highly effective in treatment of 87 patients with diabetic angiopathies of the lower extremity vessels. The frequency of specific and nonspecific complications after amputations and the number of reamputations were considerably lower. PNH allowed performing restricted, little-traumatic amputations, facilitated healing of trophic ulcers and pyonecrotic foci. It also resulted in the long-term remission of the disease.

Marked hemodilution increases neurologic injury after focal cerebral ischemia in rabbits

Moderate hemodilution (hematocrit approximately 30%) reduces neurologic injury after focal cerebral ischemia. In contrast, both clinical and experimental studies suggest that marked hemodilution (hematocrit < 30%) may exacerbate neurologic injury. We compared the effect of marked versus minimal hemodilution on cerebral infarct volume after focal cerebral ischemia in rabbits. Anesthetized New Zealand White rabbits underwent hemodilution by exchange of arterial blood with 6% high molecular weight hydroxyethyl starch. In the marked hemodilution group (n = 15) the target hemoglobin concentration was 6 g/100 mL. In the minimal hemodilution group (n = 15) the target hemoglobin concentration was 11 g/100 mL. After hemodilution, middle cerebral artery occlusion was achieved by embolizing an autologous blood clot via the internal carotid artery. Four hours after embolization, the animals were killed and their brains removed. Brains were sectioned, stained with 2,3,5-triphenyltetrazolium chloride, and infarct volumes determined via quantitative image analysis. Systemic physiologic variables were similar between groups, except for arterial hemoglobin concentration. The percentage of hemispheric infarct was significantly larger in the marked hemodilution group as compared to the minimal hemodilution group, 70% +/- 19% vs 51% +/- 23%, respectively (mean +/- SD); P = 0.02. Similarly, the percentage of infarct was greater in the hemodilution group as compared to the minimal hemodilution group in both cortex (73% +/- 18% vs 54% +/- 23%, respectively; P = 0.02) and subcortex (62% +/- 25% vs 44% +/- 23%, respectively; P = 0.04). These findings indicate that marked hemodilution exacerbates neurologic injury resulting from permanent focal ischemia. Although some degree of hemodilution may improve neurologic outcome, the advantage is lost at an extreme level of therapy.

Alteration of cerebral microcirculation by hemodilution with hemosome in awake rats

Our study showed that hemodilution with modified fluid gelatin resulted in an increase in local cerebral blood flow (LCBF), but no change at all in local cerebral oxygen delivery (LCOD) in rats. Hemosome, a lecithin encapsulated hemoglobin having the oxygen-carrying capacity, was developed to improve LCOD by hemodilution. Therefore, we have hypothesized that LCBF & LCOD would be increased by hemodilution with hemosome. To test this hypothesis, adult male Sprague-Dawley rats weighing approximately 350g were used and divided into the hemodilution and the control groups. Hemosome was made from pig red blood cells and lecithin. It's mean diameter was approximately 0.3 um and hemoglobin concentration was approximately 4g/dl. Isovolemic hemodilution, which lowered the systemic hematocrit from approximately 50% to approximately 30%, was achieved by rapidly replacing blood with the same volume of hemosome. Ten min later, LCBF in 14 brain structures were measured using the 14C-iodoantipyrine technique. Our results showed that LCBF of the control group ranged from 115 +/- 11 ml/100g/min in the medulla to 260 +/- 31 ml/100g/min in the occipital cortex. LCBFs were generally higher (p < 0.05, MANOVA) by 16% in the hemodilution group than in the control group. However LCODs were generally decreased (p < 0.05, MANOVA) by 18% in the hemodilution group than in the control. In conclusion, hemodilution with hemosome indeed improves LCBF but lowers LCOD in awake rats.

[Enhancement of cardiac performance for prevention and treatment of delayed cerebral ischemia caused by vasospasm]

Following subarachnoid haemorrhage, delayed cerebral ischaemia from cerebral vasospasm remains the most important cause of mortality and morbidity in patients with surgically secured aneurysms. Therapy with haemodilution, hypertension and volume expansion has been recommended to prevent and treat delayed cerebral ischaemia in these patients on the basis of uncontrolled clinical series (level of evidence III to V, grade C recommendation). Despite the lack of controlled studies, the maintenance of a cardiac index > 3.5 L.min-1.m-2 and a systolic arterial pressure between 120 and 150 mmHg before clipping and 160 to 200 mmHg thereafter is recommended as a prophylactic or therapeutic measure for vasospasm. Close monitoring of neurological and cardiorespiratory status is important to avoid neurologic and systemic complications.

[Indications and role of albumin for vascular loading in the operating room]

Prospective clinical studies on albumin and non human colloids, administered peroperatively, were analysed. Only those with a level of evidence I or II were considered. On the basis of the cost-effectiveness ratio, albumin should not be the first choice treatment for peroperative plasma volume expansion. Low molecular weight hydroxyethylstarch is as efficient for restoration and maintenance of volaemia and colloid osmotic pressure. Albumin is administered when other colloids are contra-indicated or when their upper limit of volume has been reached.

Conservation of blood during cardiovascular surgery

Conservative use of allogeneic red blood cell (RBC) transfusion is a growing trend in cardiovascular surgery. Recent advances in blood conservation measures have reduced, and in some cases eliminated, the need for allogeneic RBC transfusions in some of these patients. Reduced reliance on allogeneic RBC transfusion requires close collaboration among the clinical pathology, anesthesia, and surgery services managing the patient. Preoperative conservation measures include donation of autologous blood and treatment with recombinant human erythropoietin (Epoetin alfa). Meticulous surgical technique, moderate hemodilution, aprotinin, hemostatic techniques, blood salvage, and autotransfusion are intraoperative measures that can reduce blood loss. Postoperatively, even severe blood deficits can often be restored with adequate diet and rest and the use of actinics.

Alternatives to allogeneic blood use in surgery: acute normovolemic hemodilution and preoperative autologous donation

Acute normovolemic hemodilution (ANH) is a common blood conservation strategy in elective surgical procedures. Moderate ANH is safe in patients > 60 years of age; ANH is not recommended for patients who have coronary artery disease, significant anemia, renal disease, severe hepatic disease, pulmonary emphysema, or obstructive lung disease. Preservation of oxygen delivery during ANH depends on the maintenance of normovolemia to avoid decompensation and falling cardiac output. Preoperative autologous donation (PAD) as a blood conservation strategy has the advantage of protecting the patient from risks associated with allogenic transfusion, but it is expensive and time consuming. No protocols have established a preference for either ANH or PAD; an early study suggested that ANH is less expensive and more effectively preserves blood components, but other researchers warn that the methodology for ANH remains unresolved.

HES 200/0.5 is not HES 200/0.5. Influence of the C2/C6 hydroxyethylation ratio of hydroxyethyl starch (HES) on hemorheology, coagulation and elimination kinetics

The plasma clearance of hydroxyethyl starch (HES) depends on the initial molecular weight and the degree of substitution. So far, little attention has been paid to the clinical relevance of the C2/C6 substitution ratio of hydroxyethyl starch. 10 patients with cerebrovascular circulatory disturbance received hemodilution therapy for 10 days, consisting of 10% HES 200/0.5 (mean molecular weight 200 kD, degree of substitution 0.5) with a C2/C6 ratio of 13.4. A second group of 10 patients received a starch solution with identical initial molecular weight and degree of substitution but with a C2/C6 ratio of 5.7. After the administration of a single dose, no significant differences between the two groups were observed. After repeated administration, significant differences could be detected in hemorheology, coagulation and elimination (p < 0.01). The larger C2/C6 ratio led to a higher intravascular mean molecular weight (95 vs. 84 kD), which in turn led to a higher increase in serum concentration during the therapy (14.7 vs. 8.6 mg/ml). Hematocrit was lowered more (-30.5 vs. -23.5%) and plasma viscosity was increased more. There was also a more pronounced increase in partial thromboplastin time (+30% vs. +13%) and a factor of 2 larger decrease of factor VIII/von Willebrand factor-complex (p < 0.01), which exceeded the dilution effect. The higher C2/C6 ratio of HES 200/0.5/13.4 slows down enzymatic degradation. After repeated administration of this starch, large molecules accumulate which are inefficiently degraded. The same effect has been observed after therapy with highly-substituted HES. This accumulation of large molecules leads to a beneficial longer lasting volume effect. The disadvantages include an increase in plasma viscosity and coagulation disturbances, which cannot be explained with the respective dilution effect alone. For these reasons, the C2/C6 ratio is of clinical relevance and should be included in the product labeling in the future.

Blood management in orthopedic surgery

The orthopedic surgeon has several options available for blood conservation. Preoperative autologous donation (PAD) of blood is a cost-effective measure when the cost of managing transfusion-transmitted infectious disease is considered; overuse and underuse are expensive problems, however. Hemodilution, while used successfully in prostate surgery, is logistically impractical in joint replacement centers. Intraoperative blood salvage, although costly, is useful in orthopedic procedures when the anticipated blood loss is > 1,000 mL. Reinfusion of postoperative drainage that has been filtered and washed is being used in some orthopedic procedures. Studies are under way to determine whether this method of blood conservation alters transfusion requirements. Recombinant human erythropoietin (Epoetin alfa) has a role in elective procedures with significant blood loss, including complex revision joint replacement, bilateral joint arthroplasty, and spinal fusion. Preoperative Epoetin alfa administration enhances preoperative autologous blood collection and increases perioperative red blood cell mass.

Hemodilution is an effective treatment for reperfusion edema after lung transplantation

A 38-year-old patient underwent left single-lung transplantation for end-stage histiocytosis with secondary pulmonary hypertension and polycythemia. Despite use of an optimal lung graft and a total ischemia limited to 250 minutes, major pulmonary edema developed postoperatively. Hemodilution resulted in a quick recovery of lung function. We speculate that blood hyperviscosity was a major factor of pulmonary edema in this patient.

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.

Reduction in prime volume attenuates the hyperdynamic response after cardiopulmonary bypass

BACKGROUND

A hyperdynamic response to cardiopulmonary bypass is characteristically observed in the post-operative course. To determine the effect of prime volume on the hemodynamic response, a database study was performed on patients who underwent elective coronary artery bypass grafting with an extracorporeal circuit with either a large prime volume (2,350-mL prime, n = 20) or a small prime volume (1,400-mL prime, n = 20).

METHODS

Measurements were carried out at fixed time points before and after cardiopulmonary bypass (until 18 hours postoperatively) and include hematocrit, colloid oncotic pressure, fluid balance, and hemodynamic profile (mean of three measurements).

RESULTS

The lower colloid oncotic pressure in the large prime group (16.2 +/- 0.6 mm Hg versus 19.1 +/- 1.1 mm Hg, p = 0.0002) was associated with a highly positive fluid balance (5.5 +/- 0.9 L versus 2.8 +/- 0.7 L, p = 0.0001). With the on-bypass hematocrit aimed at 22% to 23%, autologous blood was predonated by 16 patients in the small prime group but by none in the large prime group. Reinfusion of autologous blood resulted in a reduction in blood bank requirements (p = 0.03). Mean arterial pressure was 83 +/- 4 mm Hg for small prime versus 76 +/- 4 mm Hg for large prime (p = 0.01). Cardiac index was 2.9 +/- 0.2 L.min-1.m-2 for small prime versus 3.8 +/- 0.3 L.min-1.m-2 for large prime (p = 0.0001). Pulmonary vascular resistance index was 281 +/- 40 dyne.s.cm5.m-2 for small prime versus 188 +/- 22 dyne.s.cm5.m-2 for large prime (p = 0.0009). Oxygen delivery was 42 +/- 5 mL.min-1.m-2 for small prime versus 51 +/- 3 mL.min-1.m-2 for large prime (p = 0.004). Vasoactive medication was not different among groups.

CONCLUSIONS

Reduction in prime volume attenuates the hyperdynamic response after cardiopulmonary bypass. Furthermore, an important reduction in blood bank products can be obtained with small prime volumes.

Ischemia-reperfusion injury of the spinal cord: the influence of normovolemic hemodilution and gradual reperfusion

Recent studies have suggested that oxygen-derived free radicals play an important role in ischemia-reperfusion injury of the spinal cord. In other organ systems, reperfusion injury has been reduced by limiting the availability of oxygen in the reperfusion phase. The purpose of this study was to test the effect of normovolemic hemodilution and gradual reperfusion on spinal cord function after aortic cross-clamping in 84 New Zealand White rabbits. All animals underwent 21 min of infrarenal aortic cross-clamping in the conscious state by means of a previously placed aortic occlusion device and were randomized to four groups. Group 1 animals were hemodiluted to a mean (s.e.m.) hematocrit of 28(2)% by extracting 25% of the effective blood volume and reinfusing the plasma component after centrifugation concurrently with a volume of normal saline three times that of the discarded red cells. Group 2 animals (controls) were bled similarly but both plasma and red cells were reinfused, resulting in a mean (s.e.m.) hematocrit of 38(2)%. In the next two groups, distal aortic flow was recorded via an implantable Doppler device. After cross-clamping, flow was returned gradually over 45 min in animals of group 3, and abruptly in group 4. Animals were observed for 5 days and neurologic function was graded by an independent observer. Paraplegia at 5 h after clamping occurred in 75% of animals in group 1 versus 32% in group 2 (P < 0.05), and in 33% of group 3 versus 28% in group 4 (not significant). Of those animals showing initial neurologic recovery, delayed-onset paraplegia was seen in 100% in group 1 versus 87% in group 4 (not significant), and in 50% of group 3 versus 92% of group 4 (P < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute normovolaemic haemodilution does not reduce the inflammatory process induced by facial surgery

The place of preoperative acute normovolaemic haemodilution (haematocrit = 28%-32%) in reducing postoperative inflammation was evaluated after facial surgery. Thirty-two patients scheduled for mandibular osteotomy were randomized to a nonhaemodiluted group or to a haemodiluted group. The degree of postoperative inflammation was evaluated: first by an x-ray technique (radiotelemetry) providing measurements of the tissue thickness (quantitation of facial oedema), and second by the measurement of four acute phase protein plasma concentrations during the first postoperative week. Throughout the study, no changes in facial oedema or in variation of acute phase proteins were detected after haemodilution. It is concluded that acute normovolaemic haemodilution has no effect on the intensity of facial oedema and the biological inflammation process after facial surgery.