Effect of Saline Irrigation for Transurethral Resection of Prostate on Acid Base and Electrolyte Status- A Prospective Cohort Study

Introduction: Transurethral Resection of Prostate (TURP), using bipolar resectoscope, is performed using 0.9% Normal Saline (NS) as irrigating fluid. The NS is absorbed at about 10-30 mL per minute of resection time. The TURP averages 45 to 90 minutes of resection time. Thus, 450-2700 mL of NS is expected to be absorbed in this short time. Rapid administration of higher quantities of NS can cause hyperchloraemic acidosis, hyperkalaemia and negative protein balance.

Aim: To detect changes in pH, serum electrolytes (serum bicarbonate, serum chloride, serum sodium, and serum potassium) and to record complications, if any, in patients undergoing bipolar TURP with 0.9% NS irrigation.

Materials and Methods: This prospective cohort study was conducted at Lokmanya Tilak Municipal General Hospital, Mumbai, Maharashtra, India, from May 2017 to May 2018. Thirty patients undergoing saline bipolar TURP under subarachnoid block were studied. Preoperative and postoperative venous blood pH and serum electrolyte samples were collected. The quantity of NS used, duration of resection, and occurrence of complications were recorded and statistically analysed.

Results: The mean age, mean gland size, resection time and volume of irrigation fluid used were 65.17±7.2 years, 64.9±30.85 cc, 60.67±14.17 minutes and 23.73±4.78 Litres, respectively. The mean preoperative pH of 7.33±0.047 fell by 0.03 postresection (p-value=0.02) and mean serum sodium increased from 139±3.65 meq/L to 142.2±3.60 meq/L, which was statistically significant (p-value=0.01). Serum bicarbonate, serum potassium, and serum chloride did not show any significant change. On relating the various intraoperative parameters with biochemical changes, a statistically significant but clinically insignificant association was found between the amount of irrigation fluid used and changes in serum sodium levels.

Conclusion: The use of approximately 23.73 L NS in 60.67 mins of resection time and gland sizes up to 64.91 cc appear to produce no clinically significant changes in pH, serum electrolytes or complications with Bipolar TURP. However, further studies are needed to determine the acid base changes and safety with higher gland sizes requiring prolonged resection times and subsequently higher NS absorption.