[Hyponatremia during transurethral resection of the prostate].

In a retrospective study of 222 patients who underwent transurethral resection of the prostate under spinal anesthesia, plasma sodium levels during the operation were examined. The weight of prostate resected, the volume of irrigating fluid used and the duration of the operative procedure influenced the changes in plasma sodium levels. But, these changes were not statistically significant. The rise in central venous pressure values was associated with the absorption of irrigating fluid as evidenced by a drop in plasma sodium. The central venous pressure was monitored in 77 patients. There was a statistically significant correlation between the degree of hyponatremia and the rise in central venous pressure (P less than 0.001). The rise in central venous pressure reflected a change in the patient's cardiovascular status and it was, therefore, possible to treat the hyponatremia quickly and effectively. Central venous pressure monitoring is helpful in determining hyponatremia before it becomes clinically manifest.