Briones Hospital Medicine Research Program

True Critical Hyperkalemia among Hospitalized Patients

Background: Critical hyperkalemia is a serious life threatening situation. However, we often encounter fictitious laboratory hyperkalemia due to specimen contamination or hemolysis during phlebotomy. This study determined the frequency of true critical hyperkalemia (potassium >6.5 mEq/L) among hospitalized patients in an urban tertiary care academic center.

Methods: This is a retrospective analysis of an administrative database of adult inpatient potassium (K) values from January 1, 2008 to November 30, 2009. Using a customized electronic query, questionable or unreliable specimens (i.e. classified by the laboratory as "contaminated", "quantity not sufficient", "clotted", "hemolyzed" etc.) were excluded. All 918 will be reviewed. The interim analysis of the 319 highest values is presented. The top critical values were obtained and further screened through electronic laboratory data and chart review. The criteria for true critical hyperkalemia were (1) the value was repeated and verified and (2) the clinician acted upon the abnormal value.

Result: A total of 670,094 inpatient potassium values were included and 918 instances (0.14 %) of critical hyperkalemia were identified. Only 15.9 % (51) of the top 319 values fulfilled the criteria for true critical hyperkalemia (mean 7.8 mEq/L, range 7.4- 9.8 mEq/L), indicating that the total incidence was 0.02% of all K measurements. Almost half (44%) of the fictitious values were venous panel specimens obtained from the Emergency Department. Fifty-one percent (51%) of all true critical hyperkalemic events were associated with chronic kidney disease, 49 % with acute kidney injury, 13.7 % with heart failure, and 9.8 % with cancer. Thirty-seven percent (37%) of these patients were taking angiotensin-converting enzyme inhibitors, while electrocardiogram abnormalities were noted in 43% of these patients.

Conclusions: Though critical hyperkalemia among hospitalized patient is rare, up to 15.9% of critical values represent a true medical emergency.

 

Hospital Medicine Extreme:  A review of critical laboratory values among real patients

BACKGROUND.  Established clinical reference limits of laboratory values are used to help define and prevent disease. A more useful view of clinical laboratory evaluation is to use it for disease risk evaluation rather than defining a disease.Laboratory values that significantly deviate from established reference limits are called critical or panic values. This may be indicative of life-threatening conditions that require rapid clinical intervention. Emergent response to extreme laboratory values is truly within the realm of hospital medicine. 

Because hospitalized patients are more acutely ill, critical or panic laboratory values are much more prevalent in the hospital setting compared to the out-patient clinic. Most of the hospitalist experiences have been anecdotal and are usually shared amongst colleagues and other health professionals or just discussed on the internet forum or “blog”.   As examples, we have talked about the clinical scenario for a patient with the highest lactate level we have ever experienced or discuss a case of an asymptomatic patient with an extremely low hemoglobin level.

The process of reporting critical values is part of the 2009 National Patient Safety Goals of the Joint Commission on Accreditation of Healthcare Organizations. The hospital should measure, assess and take action to improve the timeliness of reporting and receipt of critical results to responsible health professional. Alert values for physician notification is generally medical center specific and not universal. 

OBJECTIVES: This is a descriptive study which aims:

1)      To obtain the highest and the lowest critical laboratory values that are clinically important in the hospital setting

2)      To review the clinical course and outcome of patients with these extreme laboratory values

3)      To describe the process of reporting critical laboratory values in the hospital setting and find ways and means in improving the timelines and efficiency of this process

METHODS:

Setting: Urban academic tertiary level hospital, East Harlem, Manhattan, NY.

Population: All adult patients with critical laboratory values admitted to Mount Sinai Hospital

Study Design: This is retrospective review of inpatient medical records of patients with the highest and lowest critically abnormal laboratory values, from January 1, 1999 to January 1, 2009.

Inclusion Criteria: 1) Abnormal laboratory values that were confirmed or repeated and

2) The clinician believed the abnormal value was true and acted upon it

Exclusion criteria: 1) Patients with erroneous laboratory values, including but not limited to hemolyzed and contaminated blood specimens.

RECRUITMENT OF SUBJECTS:

Data warehouse/EDR inquiry will be generated to list the top 5 highest and lowest laboratory values, as listed below. From this list, the patient's medical records will be reviewed and those with erroneous laboratory values will be excluded.

  • Approximately 110 subjects will reviewed
  • Waiver for informed consent will be obtained.
  • There is no risk or potential risk to the subjects.

VARIABLES/ OUTCOMES TO BE OBTAINED/MEASURED:

A short 2-3 line clinical vignette/presentation will be obtained, including clinical scenario, working diagnosis, co-morbid conditions, intervention done, and outcome (died/survived).   Patient demographic data (age, gender, and race) and insurance coverage will also be recorded.

Selected top 5 highest and lowest laboratory values to be obtained:

  1. sodium (highest and lowest)
  2. potassium (highest and lowest)
  3. glucose (highest and lowest)
  4. calcium and ionized calcium (highest and lowest)
  5. white blood cell count (highest and lowest)
  6. hemoglobin (highest and lowest)
  7. platelets (highest and lowest)
  8. pH arterial (highest and lowest)
  9. . bicarbonate (highest and lowest)
  10. lipase (highest)
  11. 10. troponin-I  (highest)
  12. CK- Creatine Kinase- total (highest)
  13. Alcohol (ETOH)- highest

The process of reporting critical values will be analyzed. The following information will be obtained from the top 5 highest and lowest critical values:

  1. time of critical value known
  2. time of receipt of report
  3. caregiver (physician, physician extender, or nurse) who received report
  4. time of intervention

DATA RECORDING:

As is already standard practice with identifiable information in the clinical database, only authorized staff have access to patient information and will be protected by passwords. During transfer of information from the source document to the research document, all direct identifiers will be replaced by a unique code not related to subject identifiers. The key to decipher the code will be kept in a separate secure location from the data. Any links between codes and the data collected (stored in separate locations) will be destroyed at the conclusion of data analysis.  All data will be recorded in an Excel spreadsheet.

EXPECTED OUTCOME: We expect that critical or panic laboratory values are typically observed among gravely ill hospitalized patients. The process of reporting is generally timely and efficient but may need some improvement.

LIMITATION OF STUDY.  This study will not include “delta” panic values or abnormal values that showed a significant change, either rise/increase or drop/fall during the hospitalization. For example, we will not be capturing a change in a patient’s hemoglobin from 12 g/dl (during admission) to 9 g/dl (after 24 hours).