Baseline Daily Requirements for a 70Kg Patient

Volume (ml)	Glucose (g)	KJ	Na (mmol)	K (mmol)	Cl (mmol)
3000	200	3400	150	80	230

Fluid	grms/l	(ml)	Glu (g)	kJ	Na	K	Cl	Ca	Lactate	pH	Osmolality
0.9% NS	9	1000	—	—	154	—	154	—	—
5% Dextrose	5	1000	50	850	—	—	—	—	—	4	278
Hartman’s		1000	—	—	131	5	112	2	29	5 -7	278
Ringers		1000	—	—	147	4	156	2.2	—		309?

PRIMING SOLUTIONS

5% DEXTROSE

• Readily available & cheap

• Slightly hypotonic and becomes steadily more so as the dextrose is metabolised leaving the patient with a sizeable water load to excrete

• The marked dilutional effect on plasma bicarbonate produces a marked systemic metabolic acidosis with hyponatraemia & hypochloraemia

• Not recommended for diabetics as may lead to very high glucose levels during CPB

• Due to its effect in raising osmotic pressure in prime, may be associated with reduced postoperative fluid retention & perioperative fluid requirements

• However, CNS damage may occur with hyperglycaemia when associated with global or focal injury is followed by immediate reperfusion of the ischaemic region [therefore should avoid hyperglycaemia particularly in thoracic aortic repairs when are subjecting global CNS ischaemia]

HARTMAN’S

• Similar ion concentration to plasma

• Lactate renders Hartman’s slightly acid until liver converts lactate into bicarbonate, eventually producing a metabolic alkalosis

• Diabetic patients are less able to handle the lactate peripherally so that it is more readily converted to glucose thereby exacerbating hyperglycaemia [use of NS or Ringer’s]

• Due to exchange of Na for K in kidneys, may exacerbate hypokalaemia

• Danger of exacerbating any metabolic acidosis by producing lactic acidosis, particularly in seriously ill patients with poor tissue perfusion or impaired hepatic function