Effect of sodium bicarbonate infusion on serum osmolality, electrolyte concentrations, and blood gas tensions in cats

Dennis J. Chew From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 1935 Coffey Rd, Columbus, OH 43210.

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Mark Leonard From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 1935 Coffey Rd, Columbus, OH 43210.

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William W. Muir III From the Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 1935 Coffey Rd, Columbus, OH 43210.

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SUMMARY

The effects of single iv injections of sodium bicarbonate (0.5 mEq/kg of body weight, 1 mEq/kg, 2 mEq/kg, and 4 mEq/kg) on serum osmolality, serum sodium, chloride, and potassium concentrations, and venous blood gas tensions in 6 healthy cats were monitored for 180 minutes.

Serum osmolality increased and remained significantly (P < 0.05) increased for 120 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium was increased significantly (P < 0.05) for 30 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium decreased and remained significantly (P < 0.05) decreased for 120 minutes in cats given 1 g of 20% mannitol/kg, and serum osmolality was significantly (P < 0.05) decreased at 30 and 60 minutes. Serum chloride decreased significantly (P < 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and was significantly decreased for 30 minutes in cats given 2 mEq and 4 mEq of sodium bicarbonate/kg. Serum chloride decreased and remained significantly (P < 0.05) decreased for 30 minutes in cats given 1 g of 20% mannitol/kg. Serum sodium and serum osmolality did not change significantly (P < 0.05) in cats given 4 ml of 0.9% sodium chloride/kg.

Serum potassium decreased significantly (P < 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and for 120 minutes in cats given 2 mEq/kg or 4 mEq/kg. There was a significantly (P < 0.05) greater decrease in serum potassium that lasted for 30 minutes after giving sodium bicarbonate at the dosage of 4 mEq/kg, compared with other dosages given. Serum potassium did not change significantly in cats given 1 g of 20% mannitol/kg, but was significantly (P < 0.05) decreased 10 minutes following 4 ml of 0.9% sodium chloride/kg.

Sodium bicarbonate infusion significantly (P < 0.05) increased venous blood pH and plasma bicarbonate concentration in all cats. The magnitude and duration of these changes were significantly greater following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P < 0.05) increases in Pco2 were associated only with the highest dosage of sodium bicarbonate (4 mEq/kg). Base excess increased significantly (P < 0.05) in all cats following sodium bicarbonate infusion. There were significantly (P < 0.05) greater increases in base excess lasting 30 minutes following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P < 0.05) changes in venous blood pH, Pco2, or bicarbonate were not observed in cats given 4 ml of 0.9% sodium chloride/kg, or in cats given 1 g of 20% mannitol/kg. Base excess was significantly (P < 0.05) increased for 10 minutes in cats given 1 g of 20% mannitol/kg.

As expected, 4 mEq of sodium bicarbonate/kg induced the most time- and dosage-related effects. Caution should be used when administering sodium bicarbonate iv to cats at dosages > 2 mEq/kg, because of the potential for important acid-base and electrolyte changes.

SUMMARY

The effects of single iv injections of sodium bicarbonate (0.5 mEq/kg of body weight, 1 mEq/kg, 2 mEq/kg, and 4 mEq/kg) on serum osmolality, serum sodium, chloride, and potassium concentrations, and venous blood gas tensions in 6 healthy cats were monitored for 180 minutes.

Serum osmolality increased and remained significantly (P < 0.05) increased for 120 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium was increased significantly (P < 0.05) for 30 minutes in cats given 4 mEq of sodium bicarbonate/kg. Serum sodium decreased and remained significantly (P < 0.05) decreased for 120 minutes in cats given 1 g of 20% mannitol/kg, and serum osmolality was significantly (P < 0.05) decreased at 30 and 60 minutes. Serum chloride decreased significantly (P < 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and was significantly decreased for 30 minutes in cats given 2 mEq and 4 mEq of sodium bicarbonate/kg. Serum chloride decreased and remained significantly (P < 0.05) decreased for 30 minutes in cats given 1 g of 20% mannitol/kg. Serum sodium and serum osmolality did not change significantly (P < 0.05) in cats given 4 ml of 0.9% sodium chloride/kg.

Serum potassium decreased significantly (P < 0.05) for 10 minutes in cats given 1 mEq of sodium bicarbonate/kg, and for 120 minutes in cats given 2 mEq/kg or 4 mEq/kg. There was a significantly (P < 0.05) greater decrease in serum potassium that lasted for 30 minutes after giving sodium bicarbonate at the dosage of 4 mEq/kg, compared with other dosages given. Serum potassium did not change significantly in cats given 1 g of 20% mannitol/kg, but was significantly (P < 0.05) decreased 10 minutes following 4 ml of 0.9% sodium chloride/kg.

Sodium bicarbonate infusion significantly (P < 0.05) increased venous blood pH and plasma bicarbonate concentration in all cats. The magnitude and duration of these changes were significantly greater following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P < 0.05) increases in Pco2 were associated only with the highest dosage of sodium bicarbonate (4 mEq/kg). Base excess increased significantly (P < 0.05) in all cats following sodium bicarbonate infusion. There were significantly (P < 0.05) greater increases in base excess lasting 30 minutes following administration of sodium bicarbonate at dosages of 2 mEq/kg and 4 mEq/kg. Significant (P < 0.05) changes in venous blood pH, Pco2, or bicarbonate were not observed in cats given 4 ml of 0.9% sodium chloride/kg, or in cats given 1 g of 20% mannitol/kg. Base excess was significantly (P < 0.05) increased for 10 minutes in cats given 1 g of 20% mannitol/kg.

As expected, 4 mEq of sodium bicarbonate/kg induced the most time- and dosage-related effects. Caution should be used when administering sodium bicarbonate iv to cats at dosages > 2 mEq/kg, because of the potential for important acid-base and electrolyte changes.

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