Perioperative management of sickle cell disease in paediatric cardiac surgery.
In sickle cell disease, cardiopulmonary bypass may induce red cell sickling. Partial exchange transfusion reduces the circulating haemoglobin S level. M report the management of a child with sickle cell disease who required surgical closure of a ventricular septal defect. Preoperative exchange transfusion of 50% of the total blood volume was performed with fresh packed red cells over three days Further exchange transfusion was performed as cardiopulmonary bypass commenced. The haemoglobin S level was reduced from 76% to 37%. The blood removed from the patient during the exchanges was processed allowing storage and re- infusion of the patient's plasma and platelets Combined preoperative and intraoperative exchange transfusions, instead of a single stage 50% volume exchange, was effective and potentially avoids larger haemodynamic effects Cardiopulmonary bypass was conducted at normothermia and cold cardiopleya was avoided (fibrillatory arrest was used during the surgical repair).
Key Words: sickle cell disease, cardiopulmonary bypass, ventricular septal defect, exchange transfusion
Sickle cell disease constitutes a family of haemoglobinopathies caused by the abnormal genetic substitution of glutamine by valine in the haem portion of the haemoglobin molecule. Sickle haemoglobin (HbS) forms polymers when deoxygenated and these sickle cells cause the cellular injury responsible for the clinical manifestations (1). The homozygous variety of the syndrome constitutes the more severe form where the majority of the circulating haemoglobin is HbS. Even minor deoxygenation can produce gross sickling of erythrocytes. Partial exchange transfusion allows a reduction in the circulating HbS level and increases the haemoglobin A (HbA) level, and this may provide important clinical benefits.
Cardiopulmonary bypass (CPB) is commonly associated with periods of hypoperfusion, hypothermia, acidosis and hypoxia that may trigger a profound sickle cell crisis, especially in patients with the homozygous variety. We report the perioperative management of a child with sickle cell disease who had surgical closure of a ventricular septal defect (VSD) while on CPB. Management included both pre- and intraoperative exchange transfusions.
A nine-year-old boy from Guyana (24 kg, 140 cm, BSA 0.91 m (2)) presented with a history of abdominal pain, jaundice, joint inflammation, fever, breathlessness and recurrent respiratory tract infections. There was no history of cyanosis or convulsions. His resting saturation by pulse oximetry was 99%. He had been diagnosed as having sickle cell disease at the age of six years. His preoperative laboratory data are shown in Table 1. Blood was sent for electrophoresis to assess baseline values (Table 2).
Detailed echocardiography demonstrated a perimembranous VSD, partially closed by prolapsing tricuspid valve tissue with a gradient of 104 mmHg. Percutaneous device closure was not considered, because of the probable risk of haemolysis/sickling triggered by the implant. Surgical repair was planned.
To reduce the risk of sickling and associated complications, the following plan was decided:
1. Preoperative exchange transfusion to lower the HbS level before going on CPB.
2. Sequestration of plasma and platelets from the autologous blood.
3. Normothermic CPB.
4. Repair of VSD under fibrillatory arrest (rather than cardioplegia).
5. Continuous haemofiltration and modified ultrafiltration after CPB.
6. Avoidance of acidosis during CPB.
7. Maintenance of CPB flow rates of 2.4 to 3.01/min/ml.
Preoperative exchange transfusion
Exchange transfusion was carried out on three consecutive days according to the calculations and guidelines suggested by Sutton et al (2). The exchange transfusion was performed through a femoral venous cannula, left in situ, on three consecutive days, removing aliquots of 200 ml, 200 ml and 250 ml on each day, the volume being replaced every time with 250 ml of fresh (less than six hours from collection) cross-matched packed cells collected from three donors. The patient's collected blood was centrifuged in a refrigerated centrifuge (Rotanta 460S, Germany) allowing storage of autologous plasma and platelets. Platelets were stored in a platelet agitator incubator (Terumo Penpol, India) at 22[degrees]C, while the plasma was stored in a -40[degrees]C freezer (Terumo Penpol, India). At the end of three exchange transfusions, a fresh sample of the patient's blood was sent for electrophoresis (Table 2).
The bypass circuit was primed with 500 ml of Plasmalyte A (Baxter, India), 250 ml of fresh donor packed cells, 30 ml of mannitol, 5000 units of sodium heparin and 15 ml of 75% sodium bicarbonate. After the circuit was primed, the fluid was circulated to achieve adequate oxygenation, reversal of acidosis and warming of donor packed red cells. The prime fluid was then analysed and noted to have a pH of 7.5 with haematocrit of 25%, and potassium 3.5 mmol/dl.
After systemic heparinisation with 3 mg/kg of heparin, standard aorto-caval cannulation was performed. Before CPB was initiated, 250 ml of autologous blood was drained via an adapter in the venous line and collected into a blood collection bag (Terumo Penpol, India). During this collection, systolic pressure reduced to 50 mmHg, so the procedure was stopped temporarily and CPB prime fluid infused, which stabilised the haemodynamics. The collection was slowly restarted and a total of 250 ml of autologous blood was collected. The autologous blood was centrifuged and once again the platelets and plasma stored at room temperature on this occasion (with a view to re-infusion early post-CPB). CPB was then initiated. Care was taken to maintain the temperature between 35 and 36[degrees]C and venous saturation above 75%. The VSD was closed directly using 4/0 pledgetted sutures under normothermic fibrillatory arrest. The aortic cross clamp was released and the heart was defibrillated to sinus rhythm. Continuous haemofiltration was performed on CPB. After the discontinuation of CPB, modified ultrafiltration was undertaken using suction of less than 150 mmHg to remove ultrafiltrate. Then autologous plasma and platelets were transfused after reversal of heparin with protamine.
The child was transferred to the paediatric intensive care unit (PICU) with stable haemodynamics without any inotropic support. During the postoperative period, the arterial blood gases and urine output were closely monitored and remained normal. The postoperative haemoglobin remained at 97 g/1 compared to a preoperative 102 g/1. Postoperative analgesia and sedation were provided by fentanyl and midazolam. Further recovery was uneventful, with extubation within four hours of surgery and discharge from the PICU within 24 hours.
In patients with sickle cell disease, the fraction of circulating HbS determines severity of the 'sickling' reaction. Exchange transfusion reduces the HbS level and increases the HbA level. Separation and storage of the patient's autologous plasma and platelets (from the exchange collection) and transfusion of those products at the end of CPB saves the patient's own platelets and plasma (2-5). The goal of exchange transfusion is to increase the concentration of HbA to 40% and haematocrit to 35%. This figure of 40% is arbitrary as no control studies have established the threshold ratio of HbA to HbS that will prevent significant red cell sickling (1,6,7). Our aim was to reduce the HbS level to < 40% (6,7) from the preoperative level of 76% and to increase HbA level to >40% (1). Since our patient was a nine-year-old child weighing 24 kg, it may have been difficult to maintain stable haemodynamics during a single exchange transfusion of 50% of the total blood volume. Hence, we performed exchange transfusion preoperatively by removing a total of 650 ml over a period of three days and a further 250 ml drained after venous cannulation prior to instituting CPB. This would have removed 51.42% of estimated plasma volume according to Sutton's calculations. In this patient, the combined usage of preoperative exchange transfusion as well as intraoperative exchange after venous cannulation (just before going on CPB), helped reduce the HbS level from 76 to 37% after four exchange transfusions (Table 2). Although multiple exchange transfusions have the disadvantage of subjecting the child to multiple transfusions preoperatively, the advantages are relatively safe reduction of HbS level over a period of three days and increase in HbA level from (1% to almost 60%), as well as suppression of further production of HbS (10). Preoperative exchange transfusion may be a safe alternate protocol to prevent a sickling crisis on bypass. There are reports (9) of CPB being performed on patients with sickle cell disease without preoperative exchange transfusions. Our aim was to enhance the safety of perfusion, decrease the incidence of perioperative sickle cell crisis and thus decrease the risk of perioperative multi-organ failure. Aprotinin has been suggested as having a place in patients with sickle cell anaemia undergoing cardiopulmonary bypass. We usuallyrestrict aprotinin use to patients with complex congenital heart disease where a long bypass time is expected, those with cyanotic heart disease and neonates. We believed the other measures we implemented made the risk of sickle crisis low in this child. In view of the expected short bypass time (Table 3) we did not use aprotinin.
Kingsley and others (2-4) have advocated platelet and plasma sequestration during exchange transfusion. Instead of discarding the patient's blood, we sequestrated the plasma and platelets and re-transfused them after heparin reversal. Proof of the mooted benefits of re-transfusion of the patient's own plasma and platelets in this scenario requires further study. We did not use any homologous blood or any other blood products after the procedure. Postoperative bleeding was minimal.
Most of the patient's preoperative medical history was consistent with complications of sickle cell anaemia. The frequent RTIs may have been incidental. The perimembranous VSD was small and restrictive with a gradient of 104 mmHg, so flow across the VSD was not very high and it was not expected to produce cardiopulmonary symptoms due to shunt. Closure of the defect was indicated to minimise the risk of endocarditis and further damage to the prolapsing tricuspid valve apparatus.
Acidosis and hypoxia increase the risk of sickling. To prevent acidosis, we used very fresh donor blood and added sodium bicarbonate to the prime solution, Plasmalyte A (Baxter, India), circulated with oxygen, and analysed the prime solution to confirm normal pH before instituting CPB. Fresh donor blood was added to the prime to maintain a haematocrit of 30%. Another important factor to prevent acidosis was temperature regulation. Although the HbS level was reduced preoperatively, we exercised extra caution not to trigger any adverse reaction due to hypothermia. Our institutional routine is to use cold cardioplegic arrest, but in this child, the VSD was closed using normothermic CPB under fibrillatory arrest, in order to avoid hypothermia during the brief cross-clamp time that was expected for the procedure. Since modified ultrafiltration improves lung compliance and gas exchange capacity (8), this technique was used in our patient. Our patient was extubated within four hours after surgery and discharged from the PICU within 24 hours. Nitric oxide (11) has a role in preventing or treating sickle cell crisis. In view of the relatively low level of HbS (37%) achieved during surgery in our patient, we did not use nitric oxide.
In conclusion, complications related to red cell sickling associated with open heart surgery and cardiopulmonary bypass were avoided in this child with sickle cell disease. Management included combining preoperative and intraoperative (just before instituting CPB) exchange transfusions with normothermic CPB and fibrillatory cardiac arrest rather than cardioplegia during the surgical repair.
Accepted for publication on May 29, 2007.
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(9.) Frimpong-B oaten g K, Amoah AG, Barwasser HM, Kallen C. Cardiopulmonary bypass in sickle cell anaemia without exchange transfusion. Fur J Cardiothorac Surg 1998; 14:527529.
(10.) Tziomalos K, Garipidou V, Houmpouridou E, Pitsis AA, Basayannis E. Mitral valve reconstruction in a compound heterozygote for sickle cell anemia and hemoglobin lepore. J Thorac Cardiovasc Surg 2005; 130:932-933.
(11.) Head CA, Brugnara C, Martinez-Ruiz R, Kacmarek RM, Bridges KR, Kuter D et al. Low concentrations of nitric oxide increase oxygen affinity of sickle erythrocytes in vitro and in vivo. J Clin Invest 1997; 100:1193-1198.
K. BHATT *, S. CHERIAN ([dagger]), R. AGARWAL ([double dagger]), S. JOSE ([section]), K.M. CHERIAN **
Departments of Cardiac Anaesthesiology and Critical Care Medicine, Frontier Lifeline, Chennai, India
* M.D., Consultant, Department of Cardiac Anaesthesiology.
([dagger]) M.S., Ph.D., Director and Staff Cardiac Surgeon, Department of Cardiac Surgery.
([double dagger]) M.S., M.Ch., Consultant Cardiac Surgeon, Department of Cardiac Surgery.
([section]) M.Vs., Perfusionist, Department of Perfusion Technology.
** M.S., F.R.A.C.S., D.Sc.(Hon.), Chairman and CEO, Chief Cardiac Surgeon, Frontier Lifeline.
Address for reprints: Dr K. Bhatt, Consultant, Department of Cardiac Anaesthesiology, Frontier Lifeline, R-30-C, Ambattur Industrial Estate Road, Mogappair, Chennai-600 101, India.
TABLE 1 Laboratory date-blood investigations Preoperative After intraoperative exchange (650 ml) Hb g/l 102 105 PCV % 30 31 Platelets[10.sup.9]/l 400 440 WBC[10.sup.9/]l 19.1 15.5 Urea mmol/l 8.2 7.9 Creatinine mmol/l 53 44.2 Billirubin total mg/l 34.2 22.2 Direct mg/l 6.8 3.4 Indirect mg/l 27.4 18.8 SGOT IU/l 53 53 SGPT IU/l 43 43 PTs T 15.9 C 13.5 INR 1.22 APTTs T 33 C 32 Postoperative day Day 0 Day 1 Day 4 Hb g/l 97 118 99 PCV % 29 34 29 Platelets[10.sup.9]/l 340 WBC[10.sup.9/]l 28.5 29.9 22.2 Urea mmol/l 7.1 10.7 7.1 Creatinine mmol/l 44.2 53 53 Billirubin total mg/l 34.2 15.4 Direct mg/l 6.8 1.7 Indirect mg/l 27.4 13.7 SGOT IU/l 51 41 SGPT IU/l 23 35 PTs T 20 C 13 INR 1.64 APTTs T 62 C 32 TABLE 2 HB electrophoresis-before and after exchange transfusion Test Before After three After four exchange exchange exchange transfusion transfusions transfusions (650 ml) (900 ml) HbS % 76.1 58 37.1 HbA % 1.6 31.3 59.3 TABLE 3 Summary of bypass data Blood flow range l/min 2-3 Arterial blood pressure mmHg 55-65 Temperature [degrees]C 35.6-36.5 ACT s >500 Urine output ml 501 Ultrafiltrate volume ml 250 Venous HbO2 sat % 78 Glucose mmol/l 11.5 Bypass time min 22 Aortic cross-clamp time min 10
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|Author:||Bhatt, K.; Cherian, S.; Agarwal, R.; Jose, S.; Cherian, K.M.|
|Publication:||Anaesthesia and Intensive Care|
|Article Type:||Case study|
|Date:||Oct 1, 2007|
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