A study of clinical-laboratory interface involving critical laboratory values: diagnostic errors
in physician’s interpretation of hyperkalemia
Corey Chartan, MD, Satid Thammasitboon, MD, MPHE, Ayse Arikan, MD, Geeta Singhal, MD
Background
New Reporting
for Hemolyzed
Potassium
Determine
variation in
physician
reactions to
hyperkalemia
In the pediatric population, the dilemma of how to
address hemolyzed specimens and hyperkalemia is
a common challenge. The lack of a standardized
approach to interpretation of hemolyzed samples
results in practice variation and may lead to
diagnostic errors and treatment delays. We aimed to
investigate the patterns of decision making for
critical potassium levels at our institution. This study
can be used as a prototype for the development of
guidelines to improve clinical-laboratory interface
and decrease the incidence of diagnostic errors.
Highly
reliable
decisionmaking
system
4
2
6
5
Education sessions to
various groups of physicians
3
1
Critical lab values
Casual decisionmaking
Development
of Potentially
Better
Practices
Collaborative action
with laboratory
Retrospective
chart review
We conducted a survey prior to the education
sessions to investigate how the presence of
hemolysis in the laboratory report affects residents’
decision to respond to the critical K values. The
residents were asked to select an action given
various critical K values (5.8, 6.6 and 7.4 mmol/L)
with or without hemolysis:
1) no action
2) repeat the test 4 hours later
3) repeat the test to confirm the critical
value
4) repeat the test but treat without waiting
for confirmation
5) treat without confirmation.
Fifty-five residents completed the questionnaire.
When hemolysis was reported, the residents
downgraded their action 71% of the times. This
tendency was common even with the lifethreatening K level of 7.4 mmol/L (Fig. 1). In
general, the addition of hemolysis did alter the
percentage of correct actions (Fig. 2).
Methods
1) Conducted a retrospective chart review of
episodes of hyperkalemia in one year at a universitybased children’s hospital.
2) Reviewed physician reactions to these critical lab
values and divided responses into 5 different
categories:
• 1) No action
• 2) No action but subsequently needed treatment
• 3) Confirm the test with repeat sample and wait
• 4) Treat and confirm at once
• 5) Treat without confirming the test
3) Collaborated with laboratory/pathology
department to determine potential causes and
patterns of diagnostic error when interpreting and
managing hyperkalemia
100
4) Reviewed the current thresholds for hemolysis
and found that they were too low. New levels were
used and bias percentages available on lab reports
through EMR.
80
Figure 1:
Percentage of
residents who
down shifted
their action
with addition
of hemolysis.
60
%
40
20
5) Education sessions were given to various
physicians in the hospital. A question set was used to
assess the interpretation and management of
hyperkalemia
6) Potentially better practice guidelines were
produced to help improve decision-making for
interpreting and managing hyperkalemia.
No action but subsequently needed
treatment
Confirm the test and wait
Treat & confirm the test at once
Treat without confirming the test
n(%)
K+ Levels
(17%)
(5.6-7.8)
(54%)
(5.5-9.5)
(9%)
(5.6-9.1)
(20%)
(5.6-8.9)
Table 1: Variations in physician reaction to serum Potassium levels >5.5
mmol/L
Based on a retrospective chart review of 1,004
incidents of hyperkalemia, we identified considerable
variation of practice among our physicians (Table 1).
According to our guidelines for necessary
interventions for differing degrees of hyperkalemia, a
substantial number of the cases experienced delay
in diagnosis and/or treatment (74%). There was a
tendency toward no action or delayed action
regardless of critical K levels (Table 2). Collaboration
with the laboratory unveiled inappropriately low
thresholds being used for reporting hemolyzed
specimens. This practice resulted in a large number
of unnecessary reports of hemolysis. The new
thresholds and bias percentages are shown in Table
3.
K+ Levels
Delayed
Diagnosis
and
treatment
Overdiagnosis
and
treatment
<5.5
68%
21%
5.5-5.9
6-6.9
75%
4%
81%
1%
Hemolysis
Table 3: New
way of
reporting
hemolyzed
potassium
samples with
bias levels
≥7
76%
0%
Total
74%
3%
Table 2:
Diagnostic
errors:
delayed
diagnosis
and
treatment of
hyperkalemi
a even at
life
threatening
levels.
Free Hb (old)
mg/dl
Free Hb
(new)
mg/dl
Bias
Slight
60-100
≤ 250
3.5%
Moderate
101-250
≤550
3.5-6.5%
550-1000
6.5-10%
>1000
>10%
No report,
Significant
Gross
>250
5.4
5.8
6.6
7.4
Total
Potassium Levels
Figure 2:
Percentage of
correct actions
according to
various serum
potassium levels
with and without
hemolysis
Results
Variation in Reactions
0
For those who downgraded their action, 22% and
38% of them changed their decisions from
correct to incorrect action for the K levels of 6.6
and 7.4, respectively. These are K levels that
need immediate intervention, and the degree of
hemolysis should not have changed their
decision. Overall, the decision for watchful
waiting (option 3) is common among the
residents.
We developed the potentially better practices
(Fig. 3) aimed at improving decision-making for
interpreting and managing the critical K value.
We will continue to conduct educational sessions
to various groups of healthcare providers. Quality
data collection for process, clinical and balancing
measures is ongoing.
Hyperkalemia
Potentially Better Practices Card
Potassium Values
Follow up
Intervention A
(Dietary/Medication changes)
<5.5
5.5-5.9
Intervention B
(Intracellular K shifting
Therapy + Intervention A
+consider Kayexalate )
6-6.9
Recommendations
Clinically observe
stop K in fluid, change TPN, consider medication hold/stop medication (ACEI/
ARB/spironolactone, etc,) consider Lasix
Lasix: 1mg/Kg IV or 2mg/kg PO
Sodium Bicarbonate: 1-2 mEq/kg over 5-10 minutes
Insulin (regular): IV: 0.1 unit/kg with
Glucose.IV:<5yrs:D10-5cc/kg,
>5yrs: D25- 2cc/kg
Albuterol: 2.5-10mg nebulized over 10 minutes* usually ineffective*
Kayexalate: PO 1gm/kg ( Lexicom says 15gm max, but in life threatening HyperK give
1g/kg); *PO preferred
Rectal: 1.0 g/kg/dose
Intervention C
(Stabilize cardiac membrane
+ Intervention A & B)
≥7
calcium CHLORide: 20 mg/kg/dose
calcium GLUConate: 60-100 mg/kg/dose (maximum: 3 gram/dose)
Consider Hemodialysis
Figure 3: The Potentially Better Practices Card
Conclusions
• Diagnostic errors in laboratory test interpretation
and delayed management are prevalent even in
potential life-threatening incidents such as
hyperkalemia.
• A study of clinical-laboratory interface resulted in
new reporting for hemolyzed potassium samples.
• Potentially better practices were developed to
create a highly reliable decision-making system for
interpreting and managing hyperkalemia.
Texas Pediatric Society Electronic Poster Contest