Factors influencing the osmolality and the concentrations of blood haemoglobin and electrolytes during transurethral resection of the prostate.

Twenty patients undergoing transurethral resection of the prostate (TUR) were followed every 10 min intraoperatively as well as 1 and 2 h postoperatively with measurements of blood haemoglobin concentration (B-Hb), serum sodium (S-Na), serum potassium (S-K), serum osmolality (S-osmol), blood loss, central venous pressure and volumetric determination of the irrigating fluid absorption. Changes in B-Hb correlated well with the sum of acetated Ringer solution given and intravascular irrigating fluid absorption. A transient decrease in S-Na of 1-4 mmol/l followed absorptions less than 300 ml. With larger intravascular absorptions, three stages of dilutive changes in S-Na and B-Hb are described. Extravascular absorptions resulted in mild blood parameter changes at various times after their occurrence. Absorption of irrigating fluid was associated with an increase in S-K. S-osmol decreased in conjunction with some absorptions, although the irrigating fluid was isotonic. Postoperative analyses of blood parameters gave only limited information about intraoperative complications. The only consistent pattern was associated with intravascular irrigating fluid absorption.