Assessing the Effect of Surgery and Related Variables on Perioperative Whole
Blood Potassium Levels in Hemodialysis Patients Having Outpatient Vascular
Access Procedures
Aparna Ananth MD, Viral S Shah MD, Anatole Besarab MD, Sunitha Govindaswamy MD
Departments of Anesthesiology and Nephrology, Henry Ford Hospital, Detroit MI

Background: Many anesthesiology programs are reluctant to anesthetize hemodialysis patients needing outpatient vascular access surgical procedures whose potassium is more than 5 mEq/L, fearing the risk of further hyperkalemia. This fear persists despite the higher tolerance of end stage renal disease (ESRD) patients compared to those without chronic kidney disease. The effect of vascular access surgery, anesthesia and related variables on whole blood potassium in patients on maintenance hemodialysis has not been systematically studied.
Methods: This IRB approved study recruited 100 hemodialysis patients presenting for outpatient vascular access surgical procedures whose preoperative potassium was < 6 mEq/L. Postoperative potassium was measured in 97. Paired t-test was used to compare pre- and post- operative potassium levels. Chi square analyses were used to calculate differences between proportions. Results are given as mean + SD.
Results: 46% of patients were women and 54% were men. Ethnic distribution was 69% African-American, 23% Caucasian, 6% Hispanic and 2% Asian. Diabetes mellitus was present in 49% of patients. 91 of 99 procedures were for permanent vascular access construction. Mean age was 59.5 + 14.1 years, time since last hemodialysis 1240 + 263 min, surgical duration 130 + 50 min. 68% patients had regional anesthesia, 19% general anesthesia, 10% local anesthesia with sedation for the vascular access surgical procedure.
There was no significant difference between pre-operative whole blood potassium (4.6 + 0.7 mEq/L) and post-operative whole blood potassium (4.6 + 0.9 mEq/L); 34patients had pre-operative whole blood potassium level > 5 mEq/L and the change in whole blood potassium after surgery in these patients did not differ from those with lower pre-op whole blood potassium. Only 4 out of 34 patients with initial potassium> 5 mEq/L had a post-operative potassium > 6 mEq/L.
Diabetes, age, duration of surgery, type of anesthesia, time since last hemodialysis had no effect on the changes in perioperative whole blood potassium.
Subgroup analysis indicated that graft removal (n=6) and /or thrombectomy (n=1) was associated with significant increase in whole blood potassium (4.5 + 0.9 to 5.1 + 1.1) but the only patient with a potassium> 6 mEq/L started at 6 mEq/L.
Conclusion: The fear that potassium levels in ESRD patients will increase to dangerous values during vascular access surgery because of their underlying renal illness, presence of DM, or insulin dependency is not supported by our study. The practice of canceling ESRD patients’ outpatient surgery based on a preoperative whole blood potassium >5 mEq/L is not evidence based and the decision should be individualized.

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