Dyskalemia commonly encountered in ICU may increase risk for cardiac events
France: Dyskalemia at admission to an intensive care unit (ICU) is common and is associated with increased mortality, according to a recent study published in the journal Critical Care. Further, the occurrence of cardiac events increased with dyskalemia depth. The researchers, however, found that correction of serum potassium level by day 2 may improve prognosis.
The relationship between imbalances in potassium homeostasis and cardiac events has been well established for many years. Dyskalemia was defined as a serum potassium level [K+] < 3 mmol/L or [K+] ≥ 5 mmol/L has been incorporated into the Simplified Acute Physiology Score (SAPS II) a risk prediction model in intensive care unit (ICU). Current guidelines recommend the maintenance of serum potassium levels in patients with acute myocardial infarction to be from 4.0 to 5.0 mmol/L or even 4.5 to 5.5 mmol/L.
Lila Bouadma, Bichat University Hospital, Paris, France, and colleagues conducted the study to (1) to characterize the distribution of serum potassium levels at ICU admission, (2) to examine the relationship between dyskalemia at ICU admission and occurrence of cardiac events, and (3) to study both the association between dyskalemia at ICU admission and dyskalemia correction by day 2 on 28-day mortality.
The researchers examined outcomes among 12,090 patients admitted to 22 ICUs using 1999 to 2014 data from the OUTCOMEREA database. The team stratified patients by admission serum potassium into a normokalemia group (3.5 to 5 mmol/L); 3 hypokalemia groups (mild, moderate, and severe), and 3 hyperkalemia groups (mild, moderate, and severe). The main study outcome was 28-day mortality.
Prognostic impact of dyskalemia and its correction was assessed using multivariate Cox models. The occurrence of cardiac events was evaluated by logistic regression.
Key findings of the study include:
· Of 12,090 patients, 2108 (17.4%) had hypokalemia and 1445 (12%) had hyperkalemia.
· Hyperkalemia and hypokalemia were highly prevalent among patients with a chronic kidney disease (27%) and in immunosuppressed patients (21%).
· Compared with normokalemia, moderate hypokalemia was associated with significant 47% increased odds for cardiac events in adjusted analyses.
· Mild and severe hypokalemia was not significantly associated with cardiac event risk.
· Mild, moderate, and severe hyperkalemia were associated with a significant 22%, 49%, and 89% increased risks for cardiac events, respectively.
· Mild hyperkalemia was associated with significant 29% increased odds of death within 28 days compared with normokalemia in adjusted analyses.
· Moderate and severe hyperkalemia did not significantly increased the risk of 28-day mortality. Severe hypokalemia increased the risk of 28-day mortality by a nonsignificant 29%.
· Failure to correct serum potassium levels by day 2 increased the risk of adjusted 28-day mortality.
· Dyskalemia was associated with a nonsignificant 24% increased risk, but persistent dyskalemia at day 2 was associated with a significant 45% increased risk of adjusted 28-day mortality.
· Patients undergoing renal replacement therapy on day 1 or 2 had a significant 34% risk for early death.
"Whether dyskalemia is a true cause of excess mortality responsive to treatment or merely a marker of ICU patient complexity is unclear," wrote the researchers.
The study, "Influence of dyskalemia at admission and early dyskalemia correction on survival and cardiac events of critically ill patients," is published in the journal Critical Care.