The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer-assisted potassium control

Abstract

IntroductionThe relationship between potassium regulation and outcome is not known. Our first aim in the present study was to determine the relationship between potassium level and variability in (ICU) stay and outcome. The second aim was to evaluate the impact of a computer-assisted potassium regulation protocol.MethodsWe performed a retrospective before-after study including all patients >15 years of age admitted for more than 24 hours to the ICU of our university teaching hospital between 2002 and 2011. Potassium control was fully integrated with computerized glucose control (glucose and potassium regulation program for intensive care patients (GRIP-II)). The potassium metrics that we determined included mean potassium, potassium variability (defined as the standard deviation of all potassium levels) and percentage of ICU time below and above the reference range (3.5 through 5.0 mmol/L). These metrics were determined for the first ICU day (early phase) and the subsequent ICU days (late phase; that is, day 2 to day 7). We also compared potassium metrics and in-hospital mortality before and after GRIP-II was implemented in 2006.ResultsOf all 22,347 ICU admissions, 10,451 (47%) patients were included. A total of 206,987 potassium measurements were performed in these patients. Glucose was regulated by GRIP-II in 4,664 (45%) patients. The overall in-hospital mortality was 22%. There was a U-shaped relationship between the potassium level and in-hospital mortality (P <0.001). Moreover, potassium variability was independently associated with outcome. After implementation of GRIP-II, in the late phase the time below 3.5 mmol/L decreased from 9.2% to 3.9% and the time above 5.0 mmol/L decreased from 6.1% to 5.2%, and potassium variability decreased from 0.31 to 0.26 mmol/L (all P <0.001). The overall decrease in in-hospital mortality from 23.3% before introduction of GRIP-II to 19.9% afterward (P <0.001) was not related to a specific potassium subgroup.ConclusionsHypokalemia, hyperkalemia and potassium variability were independently associated with increased mortality. Computerized potassium control clearly resulted in improved potassium metrics.

Association of Serum Potassium with All-Cause Mortality in Patients with and without Heart Failure, Chronic Kidney Disease, and/or Diabetes

“…Importantly, higher mortality occurred at potassium values that commonly engender little concern among clinicians, especially in those with HF or CKD. These findings are consistent with prior reports of U-shaped relationships between potassium and death in selected populations [10][11][12][13]. Individuals ≥ 65 years of age had noticeably higher mortality rates for mild and moderate-to-severe hypokalemia and mild to moderate-tosevere hyperkalemia when compared to those aged 50-64 years.…”

Evaluation of an Intravenous Potassium Dosing Algorithm for Hypokalemic Critically Ill Patients

“…It was our intent to ultimately achieve a serum potassium concentration within 4–4.5 mEq/L; however, the “optimal serum potassium concentration target range” for acutely ill patients is debatable. In a 10‐year retrospective analysis of 10,451 patients admitted to 3 surgical and 1 medical ICUs, a U‐shaped relationship between serum potassium concentration and in‐hospital mortality rate was observed, with the lowest mortality associated with concentrations ranging from 3.5–5 mEq/L 33 . Lower and higher concentrations were associated with higher mortality rates 33 .…”

“…In a 10‐year retrospective analysis of 10,451 patients admitted to 3 surgical and 1 medical ICUs, a U‐shaped relationship between serum potassium concentration and in‐hospital mortality rate was observed, with the lowest mortality associated with concentrations ranging from 3.5–5 mEq/L 33 . Lower and higher concentrations were associated with higher mortality rates 33 . Recommendations from other studies in different acutely ill patient cohorts based on mortality rates have varied from 3.5–4.5 mEq/L, 34 4–5 mEq/L, 25 and even as high as 4 or 4.5–5.5 mEq/L 35 , 36 .…”

Relationship between serum total magnesium and serum potassium in emergency surgical patients in a tertiary hospital in Ghana

“…While magnesium deficiency has been found in 7-11% of hospitalized patients 7 but it may be as high as 65% in Intensive Care patients. 8 Hypomagnesaemia and hypokalaemia have both been associated with poor prognosis and increased mortality in the acutely ill. 9,10,11 Hypokalaemia has been found to be frequently associated with hypomagnesaemia. Forty-two to sixty-one percent of hypokalaemic patients are also hypomagnesaemic.…”