Safety of Continuous Potassium Chloride Infusion in Critical Care

Arrhythmias, Cardiac Clinical Trial

— ASPIC  

Official title:

Assessing the Safety of a Continuous Potassium Chloride Infusion in Critical Care: A Randomised Controlled Trial

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00718068
• Other study ID #: 2007185
• Status: Completed
• Phase: Phase 4
• First received: July 16, 2008
• Last updated: July 26, 2010
• Start date: October 2008
• Est. completion date: October 2009

Study information

• Verified date: November 2009
• Source: The Queen Elizabeth Hospital
• Contact: n/a
• Is FDA regulated: No
• Health authority: Australia: Human Research Ethics Committee
• Study type: Interventional

Clinical Trial Summary

Patients in critical care often require supplemental potassium chloride if levels in their blood are below acceptable level. Common practice is to administer a single dose of potassium chloride under controlled conditions via a drip, before checking if a further dose is required. The purpose of this study is to ensure that it is safe to administer potassium chloride continuously with the dose varied according to patient needs.

Description:

The use of potassium supplementation is commonplace in the critical care environment. Patients often have abnormal serum potassium levels due to active disease processes. Conditions such as acute renal failure and metabolic acidosis precipitate hyperkalaemia, with ileus and insensible losses causing hypokalaemia. Both hypo- and hyperkalaemia can cause life-threatening arrythmias so it is prudent to rectify aberrant levels.

The standard treatment of hypokalaemia in intensive care units is by intravenous administration of potassium chloride. This can be given either as a dilute solution as maintenance intravenous fluid therapy, or as a concentrated solution by intermittent infusion. Alternatively potassium can be given as a concentrated solution by continuous infusion. All techniques require regular monitoring of the patient's serum potassium level with appropriate alterations to the administration regime.

From a theoretical standpoint it would make sense to give potassium by continuous infusion as this allow slow but steady correction of hypokalaemia. A continuous infusion should prevent rapid fluctuations in the serum level that could be caused by intermittent infusions, which may precipitate arrhythmia. However continuous infusions require vigilant monitoring to ensure that hyperkalaemia does not occur and must be given into a central vein to avoid the risk of phlebitis.

The use of intermittent infusions has been used safely in the critical care setting under physician guidance. A retrospective review reported the outcomes of the administration of 495 infusion sets to 190 individuals. While they identified 2 instances of post-infusion hyperkalaemia, neither was associated with any adverse sequelae. Analysis showed a no correlation between serum potassium increase post-infusion and serum creatinine, thus advocating the use of this therapy in patients with renal failure. In light of this valuable safety data, they proceeded with a prospective cohort study involving 40 patients on their Intensive Care Unit. Again the outcomes were favourable with a mean increase of 0.48mmol/L after administration of 20mmol in 100ml of saline over 1 hour. They reported no instances of hyperkalaemia, and data suggested a decreased instance of ectopic beats versus control patients.

The use of a variable dose regime dictated by serum potassium concentration has also been assessed. In a prospective cohort study 20, 30 or 40mmol was administered over 1 hour to 48 patients based on their initial measured potassium level. They only reported 2 instances of hyperkalaemia but neither patient experienced any complications. Usefully they found that patients with oliguric renal failure (creatinine 283 ± 127 micromol/L) had no greater mean increase in potassium level after infusion than patients with normal creatinine clearance.

Two other methods have been suggested. The first, assessed on a paediatric intensive care unit, administered potassium at a rate of 0.25mmol/kg/hr to patients with serum potassium < 3.5mmol/L and ECG abnormalities. The infusion was continued until the ECG abnormalities were corrected. Serum potassium wasn't measured until after completing the infusion, and although the mean increase was only 0.75mmol/L, this method did expose patients to a risk of unmonitored hyperkalaemia. The other involves use of a feedback system with a computer-algorithm driven protocol. This method was not developed into a full production model due to lack of cost-effectiveness.

We were unable to find any trials assessing the efficacy and safety of continuous potassium infusions in the critical care population, so felt it was time this was rectified. Critically ill patients are often hypokalaemic due to insensible losses, inadequate supplementation prior to admission, and use of diuretics and beta-agonists. At the same time they often have acute and/or chronic renal failure or may have a metabolic acidosis that will hamper normal potassium sequestration or excretion. Thus they are at risk of rapidly developing life-threatening hyperkalaemia if supplementation is not carefully titrated against serial monitoring. Continuous infusions administered with due vigilance should allow for correction of hypokalaemia in a safe and precise manner.

Our department used to supplement potassium by intermittent infusion, but after internal discussion we have successfully implemented a continuous infusion protocol. We propose that continuous infusions administered by accredited nurses under physician direction can safely deliver potassium and correct abnormal levels.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 160
• Est. completion date: October 2009
• Est. primary completion date: September 2009
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• Any inpatient on the investigating unit with a serum potassium level of less than 3.8mmol/L

• arterial line for blood sampling and central venous access for infusion administration in situ

• continuous 12-lead ECG monitoring

Exclusion Criteria:

• Patients with a serum potassium = 3.8mmol/L

• Renal dysfunction with serum creatinine 50% greater than the upper end of the normal reference range (i.e.: > 180micromol/L) or urine output less than 0.5ml/kg/hr for 6 consecutive hours, or the requirement for dialysis

• Burns

• Hypomagnesaemia (= 0.7mmol/L), however patients may be enrolled after the hypomagnesaemia is corrected

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Treatment

Related Conditions & MeSH terms

• Arrhythmias, Cardiac
• Hypokalemia

Intervention

Drug:
• Sterile Potassium Chloride Concentrate
Continuous infusion, 40mmol in 40ml, starting at 10ml/hr, rate altered according to serum potassium level checked 2 hourly
• Sterile Potassium Chloride Concentrate
By intermittent infusion, 20mmol diluted in 100ml 0.9% NaCl, administered over 60 mins, serum potassium level checked 2 hourly, and repeat doses administered as appropriate

Locations

Country	Name	City	State
Australia	The Queen Elizabeth Hospital	Woodville South	South Australia

Sponsors (1)

Lead Sponsor	Collaborator
The Queen Elizabeth Hospital

Country where clinical trial is conducted

Australia, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Adherence to a potassium level 4.0 - 4.5mmol/L		7 days	Yes
Secondary	Total quantity of potassium administered		7 days	No
Secondary	Incidence of potassium level < 3.0mmol/L and > 5.5mmol/L		7 days	Yes
Secondary	Incidence of arrhythmia		7 days	Yes
Secondary	Number of arterial blood gases taken		7 days	No