Experience with sodium fluorescein flow cytometry in the determination of red cell volume.

Sodium fluorescein flow cytometry for the calculation of red cell volume is an exciting proposition in that the repeatability of the technique in a short time frame should allow for applications such as the measurement of surgical red cell volume loss. Our results found that the rapid decay in fluorescence negated the usefulness of this technique as currently described. However, further investigation into the behaviour of the sodium fluorescein labelled red blood cells may allow for the mathematical correction of the fluorescent red cell population prior to red cell volume calculation.

Rationalizing blood transfusion in cardiac surgery: the impact of a red cell volume-based guideline on blood usage and clinical outcome.

BACKGROUND AND OBJECTIVES: Cardiac surgery is currently considered one of the heaviest users of red blood cells. An explanation may be found, in part, in considering the effect of the heavy clear fluid load associated with cardiopulmonary bypass. This may result in the artificial depression of haemoglobin concentration, overestimating the requirement for red cell transfusion if this is the sole parameter considered. To address this issue, we examined the impact of a red cell volume-based transfusion guideline on transfusion requirement. MATERIALS AND METHODS: This was a single-centre, randomized controlled trial. The cohort of 86 patients was allocated to receive red cells as per the red cell volume guideline (group RCV) or standard haemoglobin concentration-based departmental policy (group C). Outcome measures were red cell transfusion and clinical outcome. RESULTS: All preoperative data were comparable between the two groups. A significantly fewer percentage of patients in group RCV were transfused red cells (RCV = 32.6% vs. C = 53.5%, P = 0.05). No significant difference was found between any of the outcome measures with the exception of median hospital stay (RCV = 5.9 days vs. C = 6.8 days, P = 0.02). CONCLUSION: In elective cardiac surgery patients, considering haemoglobin concentration alone may overestimate the requirement for red cell transfusion. More research is required to determine the impact of restrictive transfusion policies on clinical outcome following cardiac surgery.

Rationalizing blood transfusion in cardiac surgery: preliminary findings with a red cell volume-based model.

BACKGROUND AND OBJECTIVES: Cardiac surgery, utilizing extracorporeal circulation, is associated with a heavy fluid load that may significantly depress haemoglobin concentration. Thus, considering haemoglobin alone may be an inaccurate method of replacing red cell volume loss. This study was designed to examine the impact on red cell transfusion of a red cell volume-based guideline. MATERIALS AND METHODS: Patients were randomized to receive red cells as dictated by the red cell volume-based guideline or a haemoglobin-based protocol. End-points considered were red cell transfusion and clinical outcome. RESULTS: Patients transfused as per the red cell volume-based guideline received significantly less red cells with no associated difference in clinical outcome. CONCLUSION: Considering haemoglobin concentration alone may significantly overestimate the requirement for red cell transfusion in elective cardiac surgery patients.

Factors predicting loss and gain of red cell volume in cardiac surgery patients.

Haemoglobin may be a poor indicator of changes in red cell volume (RCV) because of factors such as haemodilution. This study has been designed to analyse what peri-operative variables may be associated with loss or gain in RCV due to bleeding or transfusion. Prospective observational study. Single centre study based in a regional cardiac surgery centre. Twenty-nine elective adult cardiac surgery patients. Loss and gain of RCV were measured in theatre and for the first 24 h post-operatively. Patient and operative factors analysed were age, sex, height, weight, body surface area (BSA), induction haematocrit (Hct), estimated pre-operative RCV and antiplatelet therapy taken less than 7 days before operation, cardiopulmonary bypass (CPB) time, aortic occlusion time, minimum and maximum CPB temperatures and fluid administered. Age, sex, height, weight, BSA and induction Hct were found to predict red cell transfusion but not RCV loss. The total number of red cells transfused was significantly associated with RCV lost when expressed as a percentage reduction in the estimated pre-operative RCV but not the absolute RCV lost. Pre-operative RCV, as predicted by the variables outlined above, is more important than RCV lost in triggering red cell transfusion.

Cor triatriatum sinister presenting in the adult as mitral stenosis.

Cor triatriatum sinister is a rare congenital defect in which the left atrium is divided by a fibromuscular membrane into two distinct chambers. Classically, patients present in infancy although in some cases they remain asymptomatic until adulthood. The clinical features on presentation can mimic those of mitral stenosis due to the obstructive properties of the membrane. Cor triatriatum sinister presented in this case in an adult as mitral stenosis. Factors that may be relevant in determining late presentation are also discussed.

Significant merits of a fibrin sealant in the presence of coagulopathy following paediatric cardiac surgery: randomised controlled trial.

OBJECTIVES: The efficacy of a fibrin sealant in paediatric cardiac surgery has been demonstrated. However, its effectiveness in the presence of significant untreated coagulopathy has not been addressed. This study was designed to investigate the role of the topical application of a fibrin sealant, Beriplast P (BP), in the presence of coagulopathy following paediatric cardiac surgery. METHODS: After confirming the presence of significant post-bypass coagulopathy, patients undergoing repair of congenital heart defects using cardiopulmonary bypass were randomised to the use of BP (group BP) or no intervention (group C). BP was applied over suture lines and microvascular bleeding sites. Criteria for transfusion of blood and blood products were standardised for both groups. Outcome variables were: (1) post-operative bleeding; (2) transfusion of blood and blood products; (3) theatre time to achieve haemostasis; (4) ventilation time, intensive therapy unit (ITU) and hospital stay. RESULTS: Fifty-two patients (n=26 in each group), aged 3 days to 17.4 years were recruited. There were no hospital deaths and no significant differences in demographic or intraoperative variables that might have affected the chosen endpoints. After protamine, all patients in both groups had significant coagulopathy (P< or = 0.05 versus baseline). There were fewer patients receiving transfusions of fresh frozen plasma (FPP) in the intervention group, when compared to the control group (P< or = 0.05). Patients receiving BP spent less time in theatre to achieve haemostasis (P< or = 0.05), had a lesser amount of bleeding intraoperatively (P< or = 0.01), at 4h (P< or = 0.05) and at 24h (P< or = 0.05), required a lower amount of transfusions of red cells (P< or = 0.01), FPP (P< or = 0.05) and platelets (P< or = 0.05). There were no differences in ventilation time, length of stay in ITU or in hospital. CONCLUSIONS: Even in the presence of significant coagulopathy, intraoperative use of fibrin sealant in paediatric cardiac surgery reduces the amount of bleeding and need for transfusions of blood and blood products. The theatre time necessary to achieve haemostasis is also significantly reduced. These findings have a potential to improve clinical outcomes and enhance cost benefits.

The role of fibrin sealants in hemostasis.

Hemostasis is a prerequisite for wound healing, and under normal physiologic conditions, it is achieved by means of the coagulation cascade. However, there are a number of surgical procedures where there may be considerable benefits to the patient, surgeon, or health-care costs if hemostasis can be achieved more efficiently. The rapid and effective control of bleeding during and after surgery reduces blood loss and can help reduce postoperative complications. These improved outcomes can reduce the need for transfusion, with the associated risk of viral transmission, and have a positive impact on operative and hospital stay times. Fibrin sealants are surgical hemostatic agents derived from human plasma that reproduce the final steps in the coagulation pathway and form a stable fibrin clot. Fibrin sealants are used in a broad range of surgical procedures to assist hemostasis, including cardiovascular, hepatic, and splenic surgery, gastrointestinal hemorrhage, skin grafting, and dental extractions in anticoagulated patients. Patients with coagulopathies are at high risk of prolonged or excessive bleeding during or after invasive surgery, and these patients may also benefit from the use of fibrin sealants. This article reviews the role of fibrin sealants in hemostasis, citing a number of key clinical studies that report a significant reduction in blood loss or chest drain output after surgery with fibrin sealant compared with controls.

Individualized heparin and protamine management in infants and children undergoing cardiac operations.

BACKGROUND: Measurements of activated coagulation time do not correlate with plasma concentration of heparin. This study investigated the effects of a patient-specific method to manage anticoagulation and its reversal in pediatric patients undergoing cardiopulmonary bypass. METHODS: Infants and children were randomly assigned to receive either a standard dose of heparin (300 IU/kg; group C, n = 13) or an individualized dose, calculated by an in vitro heparin dose-response test (group HC, n = 13). Protamine dose was based on a 1 mg/l mg ratio of total administered heparin for patients in group C and of the residual heparin concentration in group HC. RESULTS: Administered heparin was significantly higher and total protamine dose was significantly reduced in the HC group (both p < or = 0.001). There was less thrombin generation (p = 0.02) and fibrinolysis (p = 0.05) in group HC. Blood loss and requirement for transfusion of blood and fresh frozen plasma were also lower in group HC (all p < or =0.05). CONCLUSIONS: An individualized management of anticoagulation and its reversal results in less activation of the coagulation cascade, less fibrinolysis, and reduced blood loss and need for transfusions. Further studies are warranted to better define the clinical impact of these findings.

Management of anticoagulation and its reversal during paediatric cardiopulmonary bypass: a review of current UK practice.

Protocols for management of heparin and protamine administration in patients undergoing open-heart surgery have been developed from experience gained mainly in adult practice. However, it has been demonstrated that there are marked differences between paediatric and adult patients in their response to systemic anticoagulation and its reversal. The aim of this study was to obtain an overview of current practice of management of anticoagulation and its reversal from paediatric cardiac surgical units of Great Britain and Ireland. All centres performing paediatric cardiac surgery agreed to participate in the survey (n = 16). Telephone interviews were carried out with the chief or a senior perfusionist from all participating institutions, which were based on a structured questionnaire compiled specifically for the purpose. The answers were anonymised. At present, in the UK and Ireland, unfractionated heparin is the anticoagulant of choice in all units, with a slight prevalence of porcine mucosal (9/16, 56.5%) versus bovine lung preparation (7/16, 44.0%). The policy for administration of heparin to the patient is uniform, with a dose of 300 IU/kg. However, there is great variability in the amount of heparin added to the prime and to the volume infused during cardiopulmonary bypass (CPB). Monitoring of anticoagulation is achieved by activated coagulation time alone in all but one centre, with lower limits varying between 400 and 750 s. Use of aprotinin is widely accepted, but clinical indications are highly variable. No centre adopts heparin-bonded or heparin-coated circuitry for CPB. Calculation of initial and additional protamine doses followed a variety of criteria, resulting in a very wide distribution of doses. The data obtained highlighted the lack of uniformity among paediatric cardiac surgical units of Great Britain and Ireland with regard to most of the issues related to the management of anticoagulation and its reversal. The striking heterogeneity of our cross-sectional observations clearly underlines the need for prospective, multicentre studies on a national basis to relate different clinical practices to outcome measures.

Asymptomatic congenital oesophageal cyst infiltrating the lung: an unusual complication.

An asymptomatic 14-year-old boy presented with minor chest trauma. Chest X-ray showed opacity in the upper zone of the left lung. Further investigations with magnetic resonance imaging showed it to be a posterior mediastinal mass with a fistula to the lung, along with cystic changes in the left upper lobe of lung. Left upper lobectomy with excision of the mass was performed. Histological examination later showed an oesophageal duplication cyst with a fistula to the left upper lobe of the lung. We present this unusual complication of an oesophageal cyst infiltrating the lung in an asymptomatic child.

Late aortic homograft valve endocarditis caused by Cardiobacterium hominis: a case report and review of the literature.

An unusual case of Cardiobacterium hominis endocarditis involving an aortic homograft valve is presented. Although the patient was young (a 17 year old man) and showed few of the characteristic features of the disease, the report does illustrate a number of the problems associated with this illness and highlights the need for the careful assessment of apparent culture negative endocarditis. The organism itself is susceptible to most antibiotics but further treatment, including surgery, may be necessary. Patients must therefore be examined repeatedly and assessed for haemodynamic deterioration, valve destruction or embolic phenomena. Homograft valve replacement may offer some benefits in the setting of aortic valve endocarditis and is therefore an attractive option in this situation.

Early therapeutic experience with the endothelin antagonist BQ-123 in pulmonary hypertension after congenital heart surgery.

OBJECTIVE: To assess the effect of endothelin type A (ET(A)) receptor antagonism in infants with pulmonary hypertension following corrective surgery for congenital heart disease. DESIGN: Open label, preliminary study. SETTING: Tertiary paediatric cardiothoracic surgical centre. PATIENTS: Three infants (aged 3 weeks, 7 weeks, and 8 months) with postoperative pulmonary hypertension unresponsive to conventional treatment, including inhaled nitric oxide. INTERVENTIONS: Patients received incremental intravenous infusions (0.1 to 0.3 mg/kg/h) of the ET(A) receptor antagonist BQ-123. MAIN OUTCOME MEASURES: The response to BQ-123 administration was determined using continuous invasive monitoring of cardiorespiratory variables. RESULTS: BQ-123 infusion caused a reduction in the ratio of pulmonary to systemic pressures (0.62 (0.01) to 0.52 (0.03), mean (SEM)) with an accompanying decrease in right ventricular stroke work index (4.6 (0.4) to 2.5 (0.3) g/m) and a tendency for the cardiac index to rise (2.1 (0.2) to 2.7 (0.6) l/min/kg/m(2)). This was associated with a well tolerated fall in the arterial partial pressure of oxygen (16.5 (4.1) to 12.4 (3.3) kPa) and mean systemic arterial pressure (57 (3) to 39 (3) mm Hg). CONCLUSIONS: ET(A) receptor antagonism in infants with postoperative pulmonary hypertension after corrective surgery for congenital heart disease led to significant improvement in pulmonary haemodynamic indices. However, these benefits were associated with reductions in systemic blood pressure and arterial oxygen saturation, the latter consistent with a ventilation-perfusion mismatch. On the basis of these results, studies in pulmonary hypertension will need to proceed with caution.

Persistent pulmonary hypertension of the newborn associated with pulmonary atresia and intact interventricular septum.

Neonates with pulmonary atresia and intact interventricular septum (PAIVS) do not have pulmonary vascular disease secondary to their heart abnormality. Persistent pulmonary hypertension of the newborn has not been described in association with this condition. The case is reported of a female neonate born with PAIVS, who preoperatively had no clinical evidence or any risk factors for persistent pulmonary hypertension of the newborn, but whose postoperative course was highly suggestive of persistent pulmonary hypertension; necropsy confirmed the features of pulmonary vascular disease.

Beneficial effects of inhaled nitric oxide in hypoxaemic patients after coronary artery bypass surgery.

OBJECTIVE: Arterial oxygenation may be impaired in the early period after open-heart surgery, with an associated increase in ventilation time, morbidity and hospital stay. We tested the hypothesis that inhaled nitric oxide could be a useful therapeutic adjunct in this setting. We sought to establish clinical benefits (if any), safety and the appropriate dose range of inhaled nitric oxide therapy in hypoxaemic patients after coronary artery bypass graft surgery. METHODS: Forty patients who satisfied our definition of post-operative impaired oxygenation were prospectively randomised. The treatment group (n = 20) received nitric oxide in addition to ventilatory support. While the control group (n = 20) was managed only by conventional ventilatory support. Cardio-respiratory parameters and clinical outcome measures were compared. RESULTS: We determined the optimum concentration of inhaled nitric oxide as 20 ppm in the majority (60%) of patients. Treatment improved arterial oxygenation (8.4 +/- 1.4 kPa before, 11.8 +/- 1.5 kPa after 4 h, P < 0.001) and this benefit was sustained with lower oxygen fractions required at 24 h (P < 0.001). A significantly shorter period of mechanical ventilation was required in the treatment group (mean ventilation hours 67.0 +/- 5.9 vs. 85.0 +/- 6.5, P < 0.05), although the study did not have the power to distinguish differences in ITU or overall hospital stay. Nitrous oxide and met-haemoglobin levels did not rise appreciably. CONCLUSION: We have established the safety and efficacy of inhaled nitric oxide, at a dose of between 10 and 30 ppm, in this group of patients. We suggest that nitric oxide and a delivery system are useful adjuvants in a cardiac surgical intensive care unit.

One-stage repair of interrupted aortic arch, aortopulmonary window, and anomalous origin of right pulmonary artery with autologous tissues.

Interruption of the aortic arch, distal aortopulmonary septal defect, and aortic origin of the right pulmonary artery with intact interventricular septum were associated findings in a 4-month-old infant who underwent successful one-stage repair without the use of any synthetic material, thus allowing for a potential for growth of both the pulmonary artery and the aorta. The baby made an uneventful recovery and remains asymptomatic 36 months after repair.

Superiority of centrifugal pump over roller pump in paediatric cardiac surgery: prospective randomised trial.

OBJECTIVE: The merits of centrifugal pump in adult cardiopulmonary bypass are well established. This study compares the effects of the Medtronic Biomedicus centrifugal pump with conventionally used roller pump in routine cardiopulmonary bypass in infants and children. METHODS: Between June 1996 and March 1997, 42 children (aged 2 days-13 years) undergoing elective cardiac surgery were assigned to either centrifugal or roller pump bypass. The following variables were studied: haemolysis (haematocrit, free plasma haemoglobin, haptoglobins), platelet activity (platelet counts, Beta-thromboglobulin), leukocyte count, cytokine release (IL-2, IL-6, IL-8), complement activation (C3a and C5a), blood and blood product requirements, urine output on bypass, post-operative blood urea, duration of ventilation, intensive care and hospital stay. RESULTS: Age, weight, disease complexity, duration of bypass, and a number of other variables were comparable in the two groups. The centrifugal pump resulted in lower plasma free haemoglobin (mean +/- SD, 50 +/- 23 vs. 72 +/- 35 mg/dl, P < 0.01), higher platelet count (133.1 +/- 34.8 vs. 63.5 +/- 29.6 x 10(9)/l, P < 0.01), less platelet activation (beta-TG 1253 +/- 633 vs. 1657 +/- 677 ng/ml; P < 0.05), less cytokine release (IL-6 329 +/- 57 vs. 392 +/- 59 pg/ml; P < 0.05), and reduced levels of C3a (4822 +/- 274 vs. 5933 +/- 393 ng/ml, P < 0.01). Differences were detected in favour of the centrifugal pump in urine output on bypass (4.1 +/- 0.5 vs. 2.3 +/- 1.9 ml/kg per h, P < 0.01), post-operative maximal urea (6.5 +/- 3.1 vs. 10.2 +/- 6.7 mmol/l, P < 0.02), ventilation time (18.9 + 6.5 vs. 56.5 + 51.7 h, P < 0.01), duration of intensive care (1.4 +/- 0.79 vs. 3.33 +/- 2.8 days, P < 0.05) and hospital stay (5.7 +/- 1.4 vs. 15.75 +/- 23.9 days, P < 0.01), but not in blood and blood product requirements (RCC: 11.26 +/- 4.6 vs. 10.77 +/- 4.2 ml/kg per 24 h, P > 0.05). CONCLUSION: The centrifugal pump as compared to roller pump results in less blood trauma, reduced platelet activation and less pronounced inflammatory response. There is also an improved renal response during and after bypass. This is translated clinically into reduced requirement for ventilation, shorter intensive care and hospital stays. These results strongly favour the use of centrifugal pump in routine paediatric cardiac surgery.