None listed
Conditions
Brief summary
Changes in acid-base balance, particularly metabolic acidosis are common in cardiac surgery with cardiopulmonary bypass. The mechanisms for such metabolic acidosis however, remain controversial, but previous research strongly suggests that the metabolic acidosis is iatrogenic in nature and that its extent and duration varies according to the priming solution of the cardiopulmonary bypass circuit. The priming solution has been implicated as one of the potential causes of the disturbances of pH associated with the development of metabolic acidosis on initiation of cardiac bypass. This acidosis is in part caused by hyperchloraemia and is more likely to occur with normal saline, which has a higher chloride load than the more balanced physiological solutions such as Plasmalyte or Hartmanns solutions. Attempts to prevent metabolic acidosis have entailed alterations to circuit prime fluids, including partial replacement of chloride by rapidly metabolised anions such as L-lactate, acetate and gluconate or else by bicarbonate. Study rationale: There are no published studies comparing Hartmann’s solution (contains anions lactate and chloride) and Plasmalyte (contains anions acetate, gluconate & chloride) as prime solutions for cardiopulmonary bypass. Both these crystalloid fluids are commonly used priming solutions for the cardiopulmonary bypass circuit. It is therefore not known if one solution has more beneficial effects on cardiopulmonary associated acidosis, strong-ion difference and unmeasured ions. Study design & hypothesis: We will conduct a single centre randomised controlled blinded study to test the hypothesis that when used as cardiopulmonary pump prime solution during cardiopulmonary bypass Plasmalyte solution will have a more favourable effect on metabolic acidosis than Hartmann’s solution. Primary endpoint: Standard base deficit on rewarming, just prior to separation from cardiopulmonary bypass Secondary endpoints: Strong-ion-difference; Total weak acids; Net-unmeasured-ions including lactate, acetate, gluconate; Serum creatinine; Renal biomarkers including: serum and urine NGAL, cystatin C; Pro-inflammatory effects using Interleukin-6; Cardiotoxic biomarkers using cardiac troponin. Inclusion criteria: Adult patients (age > 18years) undergoing elective Cardiac Artery Bypass Grafting (CABG) or valve surgery requiring cardiopulmonary bypass. No of participants: 50 Recruiting Hospital: Austin Hospital Clinical significance: A finding that Plasmalyte solution has more favourable effects than Hartmanns solution on cardiac bypass associated acidosis, strong-ion difference, and inflammation may influence the fluid chosen for prime solution in patients undergoing cardiopulmonary bypass.
Interventions
Plasmalyte 148 Intravenous Fluid Solution
Plasma-lyte 148 (pH 7.4) is a replacement electrolyte commonly used as a crystalloid priming solution for cardiopulmonary bypass prime. In addition, the presence of bicarbonate precursors (acetate and gluconate) produces a metabolic alkalinising effect that helps counteract metabolic acidosis of patients undergoing cardiopulomary bypass. It is an isontonic solution and compatible with blood or blood components.
The electrolyte composition of Plasmaly
Plasmalyte 148 Intravenous Fluid Solution Plasma-lyte 148 (pH 7.4) is a replacement electrolyte commonly used as a crystalloid priming solution for cardiopulmonary bypass prime. In addition, the presence of bicarbonate precursors (acetate and gluconate) produces a metabolic alkalinising effect that helps counteract metabolic acidosis of patients undergoing cardiopulomary bypass. It is an isontonic solution and compatible with blood or blood components. The electrolyte composition of Plasmalyte is as follows: 3 mEq of magnesium = 3 mmol/L. 140 Eq of sodium ion = 140 mmol/L. 98 mEq of chloride ion = 98 mmol/L. 27 mEq of acetate = 27 mmol/L. 23 mEq of gluconate = 23 mmol/L. 5 mEq of potassium ion = 5 mmol/L. For this clinical trial Plasmalyte will be used an a one off intervention only for the duration of cardiopulmonary bypass. Cardiopulmonary bypass will be performed using a membrane oxygenator (Sorin Monolyth; Biomedica, Mirandola, Italy). The pump rate will be set at 2.4 l.m-2.min-1 and body temperature will be kept at 32 to 34 Degrees. Plasmalyte will be infused as the cardiopulmonary bypass prime fluid prime fluid together with a standard cardioplegia solution minimising differentiating effects of exogenous ions given by this route. Prime volume to be administered: A crystalloid prime volume of 1500mL Plasmalyte will be used in this study representing 30-35% of the patient’s blood volume. Generally, the volume of prime required is either based on a standard empirically derived volume greater than a minimum safe priming volume, or is guided by the patient’s weight or body surface area. In practice the minimum volume required is that which fills both the venous and arterial limbs of the circuit and maintains adequate reserve volume in the venous reservoir to ensure that air is not entrained into the arterial side of the circuit during initiation of CPB. This volume is determined by both the calibre and length of the tubing connecting the patient to the CPB machine and by the design and therefore capacity of the venous reservoir and oxygenator. The volume of the prime in relation to the patient’s pre-CPB haematocrit determines the initial haematocrit achieved after the initiation of CPB. In adults, priming volumes are commonly in the range of 1400-1800mL, typically representing 30-35% of the patient’s blood volume. Additional fluid boluses of Plasmalyte solution will be administered to any patient if volume supplementation is required.
Sponsors
Austin Hospital
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Diagnosis
Masking
Blinded (masking used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
1. Adult patient (age > 18years) 2. Elective CABG or valve surgery 3. Requirements for cardiopulmonary bypass
Exclusion criteria
1. Decline to participate 2. Pregnancy 3. Abnormal pre-operative venous plasma bicarbonate concentration (< 22 mmol/L or > 27 mmol/L) 4. Hypercapnoeic respiratory failure 5. Chronic renal impairment (creatinine > 150 micromol/L) 6. Known diabetes mellitus or HbA1c > 10% (elevated blood acetate concentrations have been reported in patients with type 2 diabetes mellitus) 7. Chronic liver disease 8. Anaemia (haemoglobin level <10 g/dL) 9. Morbid obesity (BMI > 35kg/m2) 10. Known allergic reaction to study solutions
Outcome results
None listed