Sodium Bicarbonate

For severe metabolic acidosis:
a) Main therapeutic goal should be to eliminate the underlying cause of acidosis. If causes are not readily reversible, arterial pH is <7.2 (7.1 if diabetic ketoacidosis), and ventilatory procedures have not reduced acidemia, bicarbonate therapy should be considered. mEq of bicarbonate required = 0.5 x body weight in kg x(desired total CO2 mEq/L minus measured total CO2 mEq/L). Give ½ of the calculated dose slowly over 3–4 hours IV. Recheck blood gases and assess the clinical status of the patient. Avoid over-alkalinization. (Schaer 2006)
b) For metabolic acidosis secondary to uremia: In the majority of patients, definitive treatment of the urinary tract disorder and fluid diuresis is usually all that is required. In the unstable dog or cat with a pH <7.0 due to metabolic acidosis, sodium bicarb administration should be considered. The formula often recommended is 0.3 x body weight (kilograms) x the base deficit. This gives an approximation for the total bicarbonate deficit. Administration of one third of this dose slowly IV and the rest placed in the intravenous fluids will correct the metabolic acidosis over several hours. If measurement of blood gas is not possible and it is believed that the animal is severely acidemic, 1–2 mEq/kg of bicarbonate can be given as a slow IV bolus. Rapid intravenous boluses of sodium bicarbonate should be avoided because of the production of carbon dioxide and its diffusion into the central nervous system making CSF acidosis even worse. Other disadvantages of sodium bicarbonate administration include shifting of the oxygen/hemoglobin dissociation curve to the left and increasing osmolality. When monitoring the response to bicarbonate through the measurement of blood gases, remember that bicarbonate will increase initially in the intravascular space but then will be buffered by intracellular buffers. Immediate measurement of blood gases after bicarbonate administration may over-estimate the effect of the therapy. Diffusion and buffering of administered bicarbonate by intracellular buffers takes approximately 2-4 hours and a blood gas analysis should be performed after this time period as well. (Drobatz 2009)
c) For metabolic acidosis in acutely critical situations (cardiac arrest): Sodium bicarbonate is generally not necessary unless a metabolic acidosis was present before the arrest or the CPR is extending beyond 10- 20 minutes. It is definitely not given in those animals not being ventilated well. Both venous and arterial blood gas analysis is recommended to accurately determine if or how much bicarbonate is required. In most cases of CPR, hyperventilation alone is enough to circumvent the acidosis that occurs during CPR. (Crowe 2008) For adjunctive therapy of diabetic ketoacidosis: 

Note: Use of bicarb for this indication is somewhat controversial and its use is falling out of favor. Bicarb therapy can be dangerous in DKA for several reasons. Like insulin, bicarbonate drives potassium intracellularly, potentially worsening hypokalemia. Bicarbonate shifts the oxyhemoglobin curve to the left decreasing oxygen release at the tissue level and can lead to paradoxic central nervous system acidosis, fluid overload, lactic acidosis, persistent ketosis, and cerebral edema (O’Brien 2010).

a) If plasma bicarbonate is ≤11 mEq/L give bicarbonate therapy. Dose (in mEq) = body weight in kgs. x 0.4 x (12–patient’s bicarbonate) x 0.5. Give above dose over 6 hours in IV fluids and then recheck plasma bicarbonate or total venous CO2. If still ≤11 mEq/L, recalculate dose and repeat therapy. (Nelson & Feldman 1988)
For adjunctive treatment of hypercalcemic crisis:
a) The mEq of bicarbonate required = 0.3 x body weight in kg x (desired plasma bicarbonate mEq/L measured plasma bicarbonate mEq/L); or 1 mEq/kg IV every 10–15 minutes; maximum total dose: 4 mEq/L (Kruger et al. 1986)

For adjunctive therapy for hyperkalemic crises:
a) If serum bicarbonate or total CO2 is unavailable: 2–3 mEq/kg IV over 30 minutes if patient has decreased tissue perfusion or renal failure and does not have diabetic ketoacidosis. Must be used judiciously. (Willard 1986)
b) 1–2 mEq/kg IV slowly (Macintire 2006) 

To alkalinize the urine:
a) Dosage must be individualized to the patient. Initially give 10–90 grains (650 mg–5.85 grams) PO per day, depending on the size of the patient and the pretreatment urine pH value. Goal of therapy is to maintain a urine pH of about 7; avoid pH >7.5.) (Osborne et al. 1989)
b) For adjunctive therapy in dissolution and/or prevention of urate urolithiasis in dogs: 0.5–1 gram (⅛–¼ tsp.) per 5 kg of body weight three times daily PO. Goal of therapy is to attain a urine pH of from 7–7.5. (Senior 1989)

For metabolic acidosis:
a) Associated with colic; if pH is <7.3 and base deficit is >10 mEq/L estimate bicarbonate requirement using the formula: bicarbonate deficit (HCO-3 mEq) = base deficit (mEq/L) x 0.4 x body weight (kg). May administer as a 5% sodium bicarbonate solution. Each L of solution contains 600 mEq of bicarbonate (hypertonic) and should not be administered any faster than 1–2 L/hr. Because acidotic horses with colic tend also to be dehydrated, may be preferable to give as isotonic sodium bicarbonate (150 mEq/L). (Stover 1987)

For acidosis:
a) 2–5 mEq/kg IV for a 4–8 hour period (Howard 1986)
b) For severely dehydrated (10–16% dehydrated) acidotic calves (usually comatose): Use isotonic sodium bicarbonate (156 mEq/L). Most calves require about 2 liters of this solution given over 1–2 hours, then change to isotonic saline and sodium bicarbonate or a balanced electrolyte solution. Isotonic sodium bicarbonate may be made by dissolving 13 grams of sodium bicarbonate in 1 L of sterile water. Isotonic saline and sodium bicarbonate may be made by: mixing 1 L of isotonic saline with 1 L of isotonic sodium bicarbonate. (Radostits 1986)

For acidosis:
a) 2–5 mEq/kg IV for a 4–8 hour period (Howard 1986)
b) For severely dehydrated (10–16% dehydrated) acidotic calves (usually comatose): Use isotonic sodium bicarbonate (156 mEq/L). Most calves require about 2 liters of this solution given over 1–2 hours, then change to isotonic saline and sodium bicarbonate or a balanced electrolyte solution. Isotonic sodium bicarbonate may be made by dissolving 13 grams of sodium bicarbonate in 1 L of sterile water. Isotonic saline and sodium bicarbonate may be made by: mixing 1 L of isotonic saline with 1 L of isotonic sodium bicarbonate. (Radostits 1986)

For acidosis:
a) 2–5 mEq/kg IV for a 4–8 hour period (Howard 1986)
b) For severely dehydrated (10–16% dehydrated) acidotic calves (usually comatose): Use isotonic sodium bicarbonate (156 mEq/L). Most calves require about 2 liters of this solution given over 1–2 hours, then change to isotonic saline and sodium bicarbonate or a balanced electrolyte solution. Isotonic sodium bicarbonate may be made by dissolving 13 grams of sodium bicarbonate in 1 L of sterile water. Isotonic saline and sodium bicarbonate may be made by: mixing 1 L of isotonic saline with 1 L of isotonic sodium bicarbonate. (Radostits 1986)

For acidosis:
a) 2–5 mEq/kg IV for a 4–8 hour period (Howard 1986)
b) For severely dehydrated (10–16% dehydrated) acidotic calves (usually comatose): Use isotonic sodium bicarbonate (156 mEq/L). Most calves require about 2 liters of this solution given over 1–2 hours, then change to isotonic saline and sodium bicarbonate or a balanced electrolyte solution. Isotonic sodium bicarbonate may be made by dissolving 13 grams of sodium bicarbonate in 1 L of sterile water. Isotonic saline and sodium bicarbonate may be made by: mixing 1 L of isotonic saline with 1 L of isotonic sodium bicarbonate. (Radostits 1986)