Use of a simple, inexpensive device for collection of blood during acute normovolaemic haemodilution in a Jehovah's Witness patient.

Postoperative anaemia is a concern for patients who refuse blood products or have rare blood types. Acute normovolaemic haemodilution (ANH) is a potential solution for these challenging populations. However, protocols for ANH provide limited detail on preparation of blood collection systems. This report describes a novel protocol for ANH and an example of a patient who clearly benefited from ANH.

Venous drainage--gravity or assisted?

Since the early start of cardiopulmonary bypass, vascular access has been recognized as a main variable for obtaining optimal blood flow during cardiopulmonary bypass. In particular, venous drainage can limit the maximum flow as the wide, low-resistance, collapsible veins are connected with smaller stiff cannulas and tubing. Due to the introduction of long venous cannulas for minimally invasive cardiac surgery and the desire to limit hemodilution during cardiopulmonary bypass, more and more centers have started using assisted venous drainage techniques. This article gives an overview of these techniques, with their respective advantages and disadvantages.

Miniaturized extracorporeal circulation vs. off-pump coronary artery bypass grafting: what the evidence shows?

Recognition of the potentially deleterious effects of esxtracorporeal circulation led to off-pump coronary artery surgery (OPCAB) experiencing a surge in popularity in the initial decade after its conception. However, OPCAB has its own limitations and technical difficulties, such as coronary access, increased left ventricular size and reduced function, which may lead to the potential for suboptimal revascularization. As an alternative technique, miniaturized extracorporeal circulation (mECC) may provide a more controlled operative field in which the heart may be manipulated whilst minimizing the inflammatory, coagulopathic and haemodilutional effects of cardiopulmonary bypass. In this review, we outline the proposed benefits of the mECC system, discuss the pitfalls associated with mECC, and directly compare mECC to 'off-pump' coronary surgery for a variety of clinical and non-clinical outcomes.

The impact of dilution on intravenous therapy.

Chemically induced phlebitis continues to be an adverse reaction from the intravenous administration of infusates. The primary method used for decreasing the incidence of chemically induced phlebitis is to dilute infusates to the point where they do not cause tissue damage. The exact amount of dilution required for preventing chemically induced phlebitis is not currently known. This article describes methods for accurately determining the onset of chemically induced phlebitis and for describing the final concentration levels of infusates. Use of the tools presented could help intravenous therapy specialists refine research and, as a result, predict and possibly avoid chemically induced phlebitis.

Acute normovolemic hemodilution in a Jehovah's Witness patient: a case report.

Patients who are Jehovah's Witnesses refuse blood transfusions and blood products as a matter of faith. For surgical procedures during which substantial blood loss is possible, their refusal presents a challenge. 'Anesthetists must generally respect the requests of adults not to receive blood and thus should have a clear understanding of how they will respond in the event of bleeding. Several blood conservation techniques are available for consideration, including acute normovolemic hemodilution. This technique entails the preoperative phlebotomy of whole blood that contains a high concentration of red blood cells and coagulation Patiefactors, while replacing the lost volume with a crystalloid and/or colloid infusion. The procured whole blood can then be transfused back during or after the procedure as a treatment of hypovolemia. Leaving the procured blood continuously attached to the patient through the collection tubing makes the procedure acceptable to most Jehovah's Witness patients. Current literature is unclear when this technique should be used. In this particular case, acute normovolemic hemodilution contributed to the successful outcome of an anemic Jehovah's Witness who was undergoing major surgery.

Optimizing circuit design using a remote-mounted perfusion system.

There is a considerable amount of literature published on the detrimental effects of banked blood exposure in cardiac surgery. Likewise, in an effort to minimize blood exposure, many of these articles involve modifications to the heart-lung machine or its components to reduce priming volumes, therefore decreasing the need for banked blood administration caused by hemodilution. In this study, using Terumo's System 1 Advanced Heart-Lung machine, all the pump heads were remotely mounted off the pump base closer to the patient and to all the pump components. For example, cardioplegia, ultrafiltration, and vent and cardiotomy lines are now close to the oxygenator and to the patient, minimizing any excess tubing length. Cardiopulmonary bypass (CPB) blood use and priming volumes were compared before and after changing from a fixed perfusion system to a remote-mounted perfusion system using the same disposables and protocols. The mean differences of pump prime and CPB blood use were compared in four weight classes. In the 8- to 12-kg class, blood use was reduced from 1.84 +/- 0.55 to 1.10 +/- 0.36 units. Priming volume was reduced from 751.2 +/- 68.4 to 360.4 +/- 51.7 mL. In the 13- to 20-kg class, blood use was reduced from 1.80 +/- 0.42 to 1.04 +/- 0.28 units. Priming volume was reduced from 829.6 +/- 69.6 to 476. +/- 81.4 mL. In the 21- to 40-kg class, blood use was reduced from 1.60 +/- 0.57 to 0.92 +/- 0.49 units. Priming volume was reduced from 994.0 +/- 137.2 to 713.6 +/- 121.8 mL. In the 41+-kg class, blood use was reduced from 1.62 +/- 0.88 to 0.42 +/- 0.54 units. Priming volume reduced from 1306.3 +/- 112.9 to 875.5 +/- 96.6 mL. In conclusion, using a remote-mounted perfusion system resulted in reducing priming volumes and also significantly decreased the need for banked blood, subsequently saving the patient excessive exposure to banked blood.

Point of care hematocrit and hemoglobin in cardiac surgery: a review.

The use of point-of-care blood gas analyzers in cardiac surgery has been on the increase over the past decade. The availability of these analyzers in the operating room and post-operative intensive care units eliminates the time delays to transport samples to the main laboratory and reduces the amount of blood sampled to measure such parameters as electrolytes, blood gases, lactates, glucose and hemoglobin/hematocrit. Point-of-care analyzers also lead to faster and more reliable clinical decisions while the patient is still on the heart lung machine. Point-of-care devices were designed to provide safe, appropriate and consistent care of those patients in need of rapid acid/base balance and electrolyte management in the clinical setting. As a result, clinicians rely on their values to make decisions regarding ventilation, acid/base management, transfusion and glucose management. Therefore, accuracy and reliability are an absolute must for these bedside analyzers in both the cardiac operating room and the post-op intensive care units. Clinicians have a choice of two types of technology to measure hemoglobin/hematocrit during bypass, which subsequently determines their patient's level of hemodilution, as well as their transfusion threshold. All modern point-of-care blood gas analyzers measure hematocrit using a technology called conductivity, while other similar devices measure hemoglobin using a technology called co-oximetry. The two methods are analyzed and compared in this review. The literature indicates that using conductivity to measure hematocrit during and after cardiac surgery could produce inaccurate results when hematocrits are less than 30%, and, therefore, result in unnecessary homologous red cell transfusions in some patients. These inaccuracies are influenced by several factors that are common and unique to cardiopulmonary bypass, and will also be reviewed here. It appears that the only accurate, consistent and reliable method to determine hemodilution and establish transfusion thresholds based on nadir hematocrits during cardiopulmonary bypass, and immediately post cardiac surgery, is with the use of co-oximetry.

180 ml and less: cardiopulmonary bypass techniques to minimize hemodilution for neonates and small infants.

OBJECTIVE: To determine the efficacy of decreasing cardiopulmonary bypass (CPB) prime volume for neonates and small infants by using low prime oxygenators, small diameter polyvinyl chloride (PVC) tubing and removing the arterial line filter (ALF) in an effort to reduce intraoperative exposure to multiple units of packed red blood cells (PRBC). METHODS: Two retrospective database studies comparing neonatal CPB prime volume were undertaken: Study 1--A CPB circuit consisting of a 1/8 inch arterial line, a 3/16 inch venous line and a low prime oxygenator with 172 ml total circuit prime (n=74) was compared to a circuit with a 3/16 inch arterial line, a 1/4 inch venous line and a higher prime oxygenator with a 350 ml total circuit prime (n=74). Study 2--The 172 ml circuit (n=389) was compared to a circuit that included an ALF and had a total circuit prime volume of 218 ml (n=389). RESULTS: Study 1--of the 74 neonates and small infants whose CPB prime volume was 350 ml, 19 were exposed to two or more intraoperative exogenous PRBC units while only 3 neonates and small infants in the 172 ml prime group (n=74) received two or more units (p = 0.0002). Study 2--of the 389 neonates and small infants where an ALF was used (prime volume 218 ml), 54 were exposed to two or more exogenous PRBC units while only 36 of the 389 patients where an ALF was not used (prime volume 172 ml) received two or more units of intraoperative PRBCs (p = 0.0436). CONCLUSION: Decreasing the neonatal and small infant extracorporeal circuit prime volume by as little as 46 ml resulted in significantly fewer multiple exposures to exogenous PRBC units.

pH-stat ventilation management: a simple method of achieving this regimen.

Since the advent of extracorporeal circulation for life support during cardiac surgery, there have been varied opinions as to the best method of ventilating an oxygenator to achieve the optimum arterial blood gas. With respect to the optimum pCO2, clinical investigators have focused primarily on the pros and cons of the alpha-stat and pH-stat ventilation schemes. pH-stat is a ventilation scheme that attempts to maintain the temperature corrected pH of the arterial blood at 7.40, no matter what the actual temperature of the blood. This paper does not attempt to elucidate the benefits of one scheme over the other, but is offered to provide perfusionists with a simple method of achieving pH-stat ventilation, using a CO2 source and materials readily available in any operating room. Strict adherence to a few cautionary notes should enable any perfusionist to safely deliver pH-stat ventilation when indicated. This technique of providing pH-stat ventilation has been used at our institution for over three years. It has proven to be easy to accomplish, adjust and maintain.

[Oxygen metabolism with low hematocrit levels in the course of guided hemodilution procedure in cardiosurgical patients]. / Obmen kisloroda v usloviiakh nizkogo gematokrita pri provedenii upravliaemoi gemodiliutsii u bol'nykh kardiokhirurgicheskogo profilia.

Influence of hemodilution on the oxygen metabolism in patients, operated, using the artificial blood circulation apparatus, was studied up. Factors, determining the oxygen delivery to tissues, was estimated, correlational links between the blood rheological properties and its oxygen--transporting function were established. Experience of application of apparatus Aeprex, promoting the oxygen delivery to tissue improvement and the need in donor's blood lowering, performing operations, using the artificial blood circulation apparatus.

Comparison of three commercially available hollow fiber oxygenators: gas transfer performance and biocompatibility.

The new generation of oxygenators have improved blood flow pathways that enable reduction in priming volume and, thus, hemodilution during cardiopulmonary bypass (CPB). We evaluated three oxygenators and two sizes of venous reservoirs in relation to priming volume, gas transfer, and blood activation. To compare priming volume, gas transfer, and biocompatibility of three hollow fiber oxygenators and two different size venous reservoirs, 60 patients were randomly allocated in groups to undergo cardiopulmonary bypass. In each group, an oxygenator with a different surface area and priming volume was used: 1.8 m2 and 220 ml (group 1, n = 23), 2.2 m2 and 290 ml (group 2, n = 20), and 2.5 m2 and 270 ml (group 3, n = 17). In groups 1 and 3, a large soft shell (1900 ml) venous reservoir was used, whereas in group 2, a smaller soft shell (600 ml) venous reservoir was used. Gas transfer was assessed by calculating the oxygen transfer rate for each group and per square meter for each oxygenator group. Partial arterial oxygen pressure (paO2) and partial arterial carbon dioxide pressure (paCO2) between the groups were assessed with forward stepwise regression analysis. Biocompatibility was evaluated through measurement of platelet numbers, complement activation products (C3b/c), coagulation (thrombin anti-thrombin III complex), and fibrinolysis (plasmin anti-plasmin complex). No differences were found in oxygen transfer rate per group. However, when correcting the oxygen transfer rate for surface area, group 1 demonstrated a higher oxygen transfer rate compared with group 2 (p < 0.05) at an FiO2 of 40 and 60% and compared with group 3 at an FiO2 of 60 and 70%. The regression analysis showed that the average arterial PO2 was the highest in group 3, i.e., 79.2 mm Hg higher than in group 1 (p < 0.001) and 73.5 mm Hg higher than in group 2 (p < 0.001). Group 3 also had the lowest average arterial pCO2, 0.57 mm Hg lower than in group 1 (p = 0.004) and 0.81 mm Hg lower than in group 2 (p < 0.001). During CPB, platelet numbers decreased significantly in all groups (p < 0.001), without differences between the groups. C3b/c levels increased in all groups during CPB. At cessation of CPB the C3b/c level in group 2 (398 nmol/L(-1)) was significantly higher compared to group 1(251 nmol/L(-1); p < 0.05) and group 3 (303 nmol/L(-1); p < 0.05). Thrombin anti-thrombin III complexes and plasmin anti-plasmin complex complexes increased during CPB to significantly high levels at cessation of CPB, but there were no differences between the groups. The oxygenator with the smallest surface area and lowest priming volume (group 1) had the highest oxygen transfer rate per square meter and showed the least blood damage, as depicted by complement activation. The oxygenator with the largest blood contact surface area and improved geometric configuration (group 3) showed the lowest oxygen transfer rate per square meter. However, this oxygenator elevated oxygen partial pressure the most and reduced carbon dioxide partial pressure the most. In group 2, where a smaller venous reservoir was used, the highest blood activation was observed.

[Intraoperative hemodilutional autotransfusion using a closed circuit for patients of Jehovah's Witness].

We conducted hemodilutional autotransfusion using a closed circuit combined with a cell washing reinfusing system (Cell Saver) for two surgical patients of Jehovah's Witness. One was a 12 yr-old boy for extirpation of the teratoma in the anterior mediastinum and another was a 44 yr-old woman for left total hip replacement. The patients and their relatives had consented to the use of blood substitutes, hemodilutional autotransfusion using a closed circuit and Cell Saver. We devised a closed circuit system for hemodilutional autotransfusion combined with Cell Saver, in which two pumps for blood transfusion were used; one was for drawing blood from the femoral or the internal jugular vein and the other for returning blood to the peripheral vein. Blood volume in a bag interposed in the closed circuit was easily controlled by adjusting the speed of each pump. Blood collected from the surgical field by Cell Saver was also led to the bag. Acid citrate dextrose solution was infused into the closed circuit from the site close to the blood drawing. Both of our surgical patients were safely managed without homologus blood transfusion, although there remained some problems concerning the use of anticoagulants.

Hemodilution as a method to reduce transfusion requirements in adolescent spine fusion surgery.

STUDY DESIGN: A case-control study. OBJECTIVES: 1) To determine if hemodilution adequately meets the transfusion needs in children who undergo posterior spinal fusion for idiopathic scoliosis and 2) to compare the efficacy of the various methods used to reduce the risk of allogeneic blood transfusion at the authors' institution. SUMMARY OF BACKGROUND DATA: Methods to reduce blood loss and avoid allogeneic blood transfusion caused by extensive spinal surgery in adolescents include 1) autologous blood predonation, 2) controlled hypotensive anesthesia, 3) intraoperative salvage of shed blood (cell saver), 4) acute normovolemic hemodilution, and 5) transfusion decisions by clinical judgment rather than by a preset value of hemoglobin. Although all methods have some efficacy, it is not clear which methods, separate or combined, are best in the adolescent scoliosis population. METHODS: Hemodilution, hypotensive anesthesia, and cell saver were used in 43 children between June 1996 and July 1997. A comparison group (43 children) underwent similar surgery with hypotensive anesthesia and cell saver, but no hemodilution (between July 1995 and December 1996). These two groups were similar with respect to means of age, levels of instrumentation, magnitude of curvature, estimated blood volume, mean arterial pressure, duration of surgery, duration of anesthesia, estimated blood loss, volume returned from cell saver, volume in the hemovac drain, and length of hospitalization. The groups differed in preoperative hemoglobin and hematocrit and in volume of crystalloid used. RESULTS: Transfusions were given to 34 of 43 patients (79%) in the nonhemodilution group. These patients received 61 units of packed cells (57 autologous, 2 donor directed, and 2 allogeneic). In comparison, 16 of 43 patients (37%) in the hemodilution group required transfusion. They received 16 units of packed cells (15 autologous and 1 allogeneic). There was no significant difference between the groups with respect to postoperative hemoglobin and hematocrit immediately after surgery (hemodilution, 10.2/29.2; nonhemodilution, 10.0/29.1), postoperative day 1 (hemodilution, 9.2/26.9; nonhemodilution, 9.2/27.3), and postoperative day 2 (hemodilution 9.0/26.4; nonhemodilution, 9.2/27.1). There were non complications related to the technique of hemodilution in the 43 patients of this group. Cell saver was used in all patients, but sufficient volume to return blood to the patient was available in only 23 hemodilution patients (mean volume, 230 mL) and 25 nonhemodilution patients (mean volume, 215 mL). In only two patients of each group (< 5%) did the volume returned prevent the absolute need for additional transfusions. CONCLUSIONS: Hemodilution was safely used as a method to satisfy the perioperative transfusion requirements of adolescents undergoing extensive spinal surgery. By allowing patients to arrive at surgery with a higher preoperative hemoglobin and hematocrit, and by decreasing the quantity of predonated autologous blood-collected and therefore used, the hemodilution method may indirectly decrease the quantity of postoperative autologous transfusions in this population. Cell saver was not shown to be effective, and its selective use is recommended.

Efectos de la hemodilución normovolémica sobre la presión arterial central y periférica / Effects of the normovolemic hemodilution on central and peripheral blood pressure

Estudiamos el efecto de la hemodilución normovolémica sobre la presión arterial y periférica. A once perros anestesiados con pentobarbital y ventilados mecánicamente se les midió con catéteres Millar la presión arterial central y periférica, ubicando transductores en aorta y arteria femoral superficial respectivamente. En aorta torácica se instaló transductor electromagnético de flujo. Se administró fenilefrina (FNF) 0,4 y 1 µg/kg. y nitroprusiato (NTP) 2 y 4 µg/kg. Se midió presiones asistólica, diastólica y media, tanto central como periférica, así como flujo medio y presión crítica de cierre (PCC). La PCC se determinó por extrapolación del decaimiento exponencial de la presión arterial cuando el flujo sanguíneo se detuvo mecánicamente. Estas mediciones se realizaron en condiciones basal y alcanzado el máximo efecto de las drogas. Luego se realizó hemodilución extrayendo 30 a 35 ml/kl de sangre, y reponiendo suero fisiológico temperado, manteniendo constante la presión arterial sistólica. Finalmente se procedió a repetir las drogas vasoactivas y las mediciones hemodinámicas respectivas. La hemodilución disminuyó la PCC y la resistencia, con el consecuente aumento el flujo, sin alterar la presión arterial media. La disminución en la resistencia ocurrió independientemente de si en su cálculo se consideró o no la PCC. los efectos de FNF y NTP sobre la presión arterial central y periférica estuvieron de acuerdo a su farmacología y se mantuvieron después de la hemodilución. Sin embargo, hemodilución más NTP disminuyó la diferencia entre las presiones arteriales sistólicas periférica central. Estos resultados nos sugiere que la PCC está determinada, en parte, por las características reológicas de sangre

Selective hypothermic perfusion of canine brain.

A method for selective brain cooling by profound hemodilution with cold Ringer's lactate solution was previously reported in 1992. We recently modified this technique by combining it with an ultrafiltration and rewarming circuit between the left jugular vein and the inferior vena cava. We used 12 beagle dogs to study the efficacy of selective cerebral hypothermia induced by this modified technique. The brain temperature decreased to 28 degrees C within 5.4 +/- 2.7 minutes and to 20 degrees C within 15.5 +/- 9.4 minutes. The lowest brain and rectal temperatures were 17.0 +/- 1.8 degrees C and 32.1 +/- 2.2 degrees C, respectively. All animals survived in good condition without evidence of neurological deficits until they were killed at 10 weeks. Histological examination of the brains with 2,3,5-triphenyltetrazolim chloride demonstrated no evidence of ischemic lesions, and even in the hippocampus, there was no evidence of ischemic neuronal damage.

[Reduction in the use of donated blood in surgical medicine]. / Reduktion des Fremdblutverbrauchs in der operativen Medizin.

After rapid changes in transfusion practice over the past few years, blood conservation techniques have become standard in modern perioperative management. As a result, the amount of homologous blood products transfused has been markedly reduced in some types of surgical procedures. Provided that skillful surgical technique is applied and the use of blood products is restricted, autologous transfusion techniques (predonation of autologous blood, preoperative plasmapheresis, acute normovolaemic haemodilution, and intra- and postoperative blood salvage) can be performed with an acceptable risk for patients. In addition, stimulation of erythropoiesis with recombinant human erythropoietin, supplemental iron therapy, and improving haemostasis by aprotinin may further reduce homologous blood requirements. All patients undergoing elective surgery have to be informed about the side effects of transfusion of homologous blood products and the possibility of blood-saving methods. An individual blood conservation plan, based on the patient's status and surgery, the equipment available, and personal experience should be worked out by the responsible anaesthesiologist, whereby a combination of different methods may be most effective. If storage is necessary, autologous blood products should be preparated like homologous products. The feasibility of predonation and retransfusion of autologous blood in patients with infectious diseases like hepatitis or acquired immune deficiency syndrome and the amount of labaratomy testing are still under discussion. Although blood conservation programs are time-consuming and more expensive, they reduce the various risks of using homologous blood products.

Selective cooling of brain using profound hemodilution in dogs.

A new method of selective cooling of the brain was studied under profound hemodilution in 17 dogs. The carotid and vertebral arteries were bilaterally exposed, and the right vertebral artery was destroyed to provide an infusion route for cold solution for brain cooling. After the other three cerebral arteries were clamped simultaneously in the neck under low-dose heparinization, cold Ringer's lactate solution was immediately perfused into the right vertebral artery. Brain temperatures fell gradually in two dogs, and the experiments were terminated. In 10 dogs, the brain temperature fell to 28 degrees C within 4.4 +/- 1.5 minutes and was maintained at 27.0 +/- 1.0 degrees C for 60 minutes. During this interval, the body temperature was 33.9 +/- 1.6 degrees C, the stump pressure of the vertebral artery was 58 +/- 15 mm Hg, and the hematocrit value of cerebral venous blood was 7.2 +/- 4.2%. Inspection of the brain during infusion revealed paleness of the cortical vessels and no evidence of swelling. All animals survived in good condition until the time of death at 10 weeks. Histological examination of the brain revealed no evidence of ischemic injury. In a control study of five dogs, Ringer's solution at 38 degrees C was infused in the same manner as the cold solution. None of these dogs recovered from anesthesia. It is concluded that selective cooling of the brain under profound hemodilution has a protective effect on cerebral ischemia and provides a relatively bloodless operative field.