| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
Interact CardioVasc Thorac Surg 2007;6:335-339. doi:10.1510/icvts.2006.141226 © 2007 European Association of Cardio-Thoracic Surgery
Effects of cardiopulmonary bypass circuit reduction and residual volume salvage on allogeneic transfusion requirements in infants undergoing cardiac surgeryDepartment of Cardiothoracic Surgery and Department of Anaesthesiology, Bd 467, Erasmus MC, University Medical Center Rotterdam, dr.Molewaterplein 40, 3015 GD Rotterdam, The Netherlands Received 1 August 2006; received in revised form 22 February 2007; accepted 23 February 2007
*Corresponding author. Tel.: +31 10 4635208.
Cardiopulmonary bypass in children may cause severe hemodilution and can lead to excessive perioperative blood loss and high transfusion requirements. Minimization of cardiopulmonary bypass circuit and salvage of red blood cells from the residual volume after the procedure are widely utilized to reduce allogeneic transfusion. We evaluated the effectiveness of those measures introduced in infant cardiac surgery in our institution. This retrospective observational study included 148 consecutive infants between 1 and 12 months of age, with a body weight <10 kg, who underwent an elective cardiac operation between 1997 and 2005. Patients were divided into three groups defined by the circuit prime volume; 700 ml (Group 1), 450 ml (Group 2) and 330 ml (Group 3). In Group 1 residual volume after perfusion was discarded and in Groups 2 and 3 was processed in a cell saving device. Analyzed variables were: perioperative blood loss, transfusion of homologous blood products and cell salvage product, and hematology data. Reduction of the circuit volume significantly diminished use of red blood cell concentrates from 1.6 units to 0.8 units (P<0.0001), and fresh frozen plasma from 1.3 units to 0.4 units (P<0.0001). Utilization of the cell salvage product reduced significantly (P=0.023) the postoperative need for homologous blood transfusion. Therefore, both measures proved to be effective in reducing homologous blood transfusion in infant cardiac surgery.
Key Words: Cardiopulmonary bypass; Infant; Blood conservation; Cell salvage; Blood transfusion
Cardiopulmonary bypass (CPB) during open-heart surgery remains a non-physiological technique that may cause severe hemodilution and an acute inflammatory body response [1–4]. In children who undergo cardiac surgery, this alone can lead to excessive perioperative blood loss and high transfusion requirements. Additionally, nowadays smaller and younger patients are undergoing more complex procedures and there is strong evidence of enhanced blood loss and blood transfusion associated with these patients [5–8]. Awareness that allogeneic blood may transmit known and unknown pathogens and cause alloimmunization on future transfusion and pregnancies, stimulated development of new blood conservation policies. Despite recent advances in technology, the majority of neonates and infants still require perioperative transfusion of homologous blood components [9–11]. In this study, we retrospectively reviewed our experience with the CPB circuit minimization and cell salvage from the residual circuit volume, as the blood conservation measures in infant cardiac surgery in our institution.
2.1. Population From January 1997 to March 2005, 166 consecutive infants between 1 to 12 months of age, with body weight of <10 kg, underwent an elective cardiac operation with CPB at the Erasmus University Medical Center, Rotterdam. During this period, three different types of CPB circuits were used; each specific type was solitary utilized within the defined time frame. For the purpose of the retrospective study, patients were assigned into three groups according to the type of CPB circuit and how the residual volume after CPB was processed. Excluded were patients with preoperatively known clotting disorders, re-do procedures and postoperative reexplorations. Patients with aorta occlusion time longer than 90 min were also excluded to homogenize the groups according to the complexity of the operation. A total of 148 consecutive infants met the criteria. In Group 1 (52 patients operated from 1997 to 1999), a Cobe VPCML oxygenator with hard-shell reservoir (Cobe, Denver, CO) and priming volume of 450 ml was used. The CPB circuit was primed with 700 ml and the residual volume was discarded after the procedure. In Group 2 (54 patients operated from 2000 to 2003), a Polystan Safe Mini oxygenator with hard-shell reservoir (Maquet Cardiopulmonary, Hirrlingen, Germany), priming volume 160 ml, was utilized. The total priming volume of the CPB system was 450 ml. Residual volume after the procedure was processed by a HaemoLite 2 plus (Haemonatics, Bothwell, UK) cell-saving device with a centrifugal bowl of 100 ml. Harvested cell salvage (CS) product was of hematocrit 0.60 l/l. Group 3 (42 patients operated from 2004 until March 2005), had a Capiox Baby Rx oxygenator with hard-shell reservoir (Terumo, Tokyo, Japan), priming volume 60 ml. The CPB system volume was reduced to 330 ml. The residual volume was processed by the cell-saving device.
All the CPB systems utilized a roller pump with Postoperatively there were no complications, no re-explorations and all patients survived. Patients' gender, cardiac anomaly, age, body weight (BW), body surface area (BSA), CPB time, aorta cross-clamp time (AoX) and time at the Intensive Care Unit (ICU) are presented in Table 1.
2.2. Anesthesia, anticoagulation and cardiopulmonary bypass All patients received standard anesthesia. Anticoagulation was established with an initial bolus 300 IU/kg BW of porcine heparin (Leo Pharmaceutical Products, Weesp, The Netherlands) and additional heparin was administrated to maintain activated clotting time higher than 480 s. Initial protamine hydrochloride dose was 5 mg/kg BW (ICN Pharmaceutic, Zoetermeer, The Netherlands). Control of the heparin neutralization was performed and if necessary an extra protamine was given. The CPB prime always contained red blood cells (RBC), fresh-frozen plasma (FFP) and Ringer's Solution (Baxter, Utrecht, The Netherlands) or Gelofusine (B. Braun, Melsungen, Germany). The amount of RBC product added to the priming was calculated to achieve a hematocrit of 0.28 l/l during CPB. Nonpulsatile CPB, with mild hypothermia of 28 °C to 32 °C, was performed with blood flow rates between 1.8 l/min/m2 to 3.2 l/min/m2 to maintain venous oxygen saturation above 70% and mean arterial pressure between 40 and 60 mmHg. Myocardial protection was achieved with crystalloid cardioplegia. Administrations of RBC products, additional crystalloids or colloids during CPB were at the discretion of the perfusionist, based upon the working volumes and hematocrit levels. 2.3. Laboratory tests, blood loss and blood products transfusion Hemoglobin concentration (Hb), hematocrit (Ht) and platelet count (Thr) were measured one day before the operation, at the start and end of the operation, during the CPB at the 5 min on bypass and at the end, and after 24 h postoperatively. Blood loss was noted at the end of the operation and as the total volume collected at the ICU.Blood loss in the operation room (OR) represented the sum of blood loss calculated from swabs, discarded suction volumes and the chest drains' output. Postoperative blood loss was calculated as the total loss from the chest tubes during the ICU stay. The decision to transfuse blood products was based upon measured blood loss, patient clinical status and laboratory tests. Acyanotic patients were transfused to maintain a hemoglobin level of 6.0 mmol/l. Platelet transfusion was administrated if the platelet count at the end of CPB was <100x109/l. The volume of blood products transfused in the OR, including blood products added to the circuit prime and during the CPB, and administrated at the ICU was noted. Continuous data are presented as mean±standard error (S.E.) of the mean, categorical data are presented as proportions. Continuous independent data were compared with one-way analysis of variance ANOVA and Bonferroni (in case of equal variances) or Tamhane T2 (in case of unequal variances) post-hoc corrections were applied to the P-values for multiple comparisions. Categorical data were compared with the 2-test. A P-value <0.05 was considered statistically significant. All statistical analyses were performed using SPSS 13.0 statistical software (SPSS, Chicago, IL).
3.1. Laboratory test results and blood loss Measurements of Hb, Ht and Thr are presented in Figs. 1, 2 and 3. There were no significant differences with regard to Hb and Ht values measured the day before operation, pre-perfusion and after 24 h at the ICU, only at the end of the operation, Group 2 compared to Group 3 had significantly lower values of Hb (P=0.006) and Ht (P=0.023).
The platelet count on the day before operation was significantly lower in Group 3 compared to Group 1 (P=0.021) and Group 2 (P=0.006), but already preoperatively was not significantly different. Blood loss is presented in Table 2.
3.2. Blood product transfusions The amount of homologous blood products and CS product transfused in the OR and the ICU are presented in Table 3. Significantly more allogeneic RBC (P<0.0001) was used in the prime and during CPB in Group 1 (1.6 units) compared to Group 2 (1.1 units) and 3 (0.8 unit). Group 2 required significantly more RBC in the prime (P<0.0001) and during the bypass (P=0.024) than Group 3.
The FFP was used in significantly (P=0.0001) larger volume in the prime of Group 1 (1.2 units) versus Group 2 (0.7 unit) versus Group 3 (0.3 unit). The cell-saving product, available for Groups 2 and 3, was transfused in the OR in a significantly larger volume (P<0.0001) in Group 2 than in Group 3. Platelets concentrate transfusion was significantly higher in Group 1 in the OR (P<0.0001) but at the ICU there were no differences between the groups. Table 4 shows transfusion incidence of homologous blood products (RBC, FFP and platelets) and cell salvage product.
4.1. Circuit reduction and transfusion requirements It is undoubtedly true that the volume of the CPB circuit determines the exposure to allogeneic blood products in the majority of children weighing <10 kg. Boettcher et al. reported results related to non-sanguineous cardiopulmonary bypass in Jehovah's Witness patients weighing <5 kg and a 2.2-kg neonate [12, 13]. With a dedicated pediatric heart lung machine and small circuits (200 or 190 ml) they safely performed uneventful cardiac surgery. In our institution the CPB circuit volume was consequently reduced from 700 ml (Group 1), to 450 ml (Group 2) and further decreased to 330 ml (Group 3). This reduction was mainly obtained by introduction of smaller, new type oxygenators. Priming volume of the system did not change substantially over the years due to the use of the conventional ‘adult’ heart lung machine and the safety aspects of the system. Smaller CPB circuit was translated into a substantial reduction of the amount of homologous RBC needed in the prime; Group 1 – 313 ml, Group 2 – 205 ml, Group 3 – 167 ml, P<0.0001. At the end of CPB patients in all three groups had the same mean hematocrit of 0.27 l/l, but to achieve this Group 1 required 117 ml of RBC, Group 2 – 88 ml and in Group 3 only 60 ml. After the cessation of CPB, patients in all groups received in the OR comparable amounts of homologous RBC. Regretfully, the CS product transfusion in the OR in Groups 2 and 3 was of no relevance for allogeneic transfusion. The CS product was available not earlier than at the end of the procedure which practically limited its usage. Salvage of the residual CPB volume was already successfully introduced in adult cardiac surgery in our institution [14]. In infants, only during the ICU stay, transfusion of the CS product led to the reduction of homologous RBC use; Group 2 – 45 ml, P=0.029 and Group 3 – 38 ml, P=0.036 compared to Group 1 – 65 ml. The CS product was accepted for transfusion (according to the institution policy) only up to 12 h after it was obtained and this again limited the availability. Hishon et al. [15] demonstrated minimal chemical deterioration and limited microbiologic contamination in blood salvaged from the CPB circuit and stored at room temperature for an 18-h period. Therefore, prolongation of acceptable transfusion period for cell salvage product could be beneficial. The total volume of homologous RBC used in Group 1 was 533 ml (1.9 units), in Group 2 – 367 ml (1.3 units) and in Group 3 – 303 ml (1.1 units). Unfortunately, we did not succeed yet to reduce the exposure to homologous RBC to <1 unit per patient. Requirements of FFP during the perioperative period revealed that the patients in Group 1 received more homologous plasma than the patients in the other groups, due to the high amount of FFP used in the prime of the CPB circuit and during bypass. Incidence of platelet concentrates transfusion and the amount transfused in the OR were highest in Group 1 and correlated with the lowest value of platelet counts post CPB (trigger for transfusion) and at the end of the operation in this group. 4.2. Study design and limitations Our project was designed as a retrospective observational study to evaluate the consequences of policy changing through the years in the infant cardiac surgery in our institution. Due to the retrospective character of our study and eight-year time span involved, we were not able to apply a more demanding protocol (for example for retransfusion of cell saving product) and homogenized our study population. In addition, a formal cost–benefit analysis was not possible. We expect that a follow-up prospective study, which is already under way, will give more conclusive information on cell salvage product utilization. Minimization of the CPB circuit significantly reduced the demand of homologous blood products, both RBC and FFP, during the infant cardiac surgery. This reduction diminished patient exposure to the number of donors with all well-known benefits of this. We also showed the beneficial effect of the cell salvage from residual volume of the CPB circuit. The timing of the cell saving product availability in the OR, the amount of the product and acceptable transfusion period after the operation are of crucial importance for its effective utilization.
Related Article
This article has been cited by other articles:
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
Top
Abstract
1. Introduction
'' silicone tubing (Raumedic REHAU, Muri, Switzerland), a D736-40 Micron (Dideco, Mirandola, Italy) arterial filter and PVC 
