Six Sigma project reduces analytical errors in an automated lab

Medical Laboratory Observer, June, 2005 by Nancy Riebling, Laurel Tria

Figure 3. Failure mode and effect analysis

Analyze

Rank process steps--narrows vital Xs with risk priority number

Process step/input                            Potential failure effects
What is the process   Potential failure mode  What is the impact on the
step and input under  In what ways does the   key output variables
investigation?        key input go wrong?     (customer requirements)?

Autoverification      Rule manager not        Results released without
                      working                 review
Report result         SOP not followed        Wrong result
Sample prep           Label needs             Delay in testing, or
                      repositioning           redraw needed
Shift communication   Tech leaves early or    Satus of testing site
                      arrives late            unknown
Review results        Staffing issues         Results get delayed
Review results        LIS problems            Results get delayed
Instrument prep       Printer jams, no        Delay in testing
                      paper, toner out
Run QC                QC out of range         Testing delayed while
                                              problem corrected
Review results        Instrument problems     Results get delayed
Gather work           LIS or CLAS down and    Delay in testing
                      techs absent
Instrument startup    Out of reagents         Delay in testing
Analyze specimens     Samples not assayed     Results delayed

Process step/input              Potential causes
What is the process             What causes the
step and input under            key input to go
investigation?        SEVERITY  wrong?            OCCURRENCE  OCCURRENCE

Autoverification         8      LIS overburdened      5            5
Report result            6      Tech error            3            3
Sample prep              7      Phiebotomist's        5            5
                                technique
Shift communication      8      Tech does not
                                inform anyone of      6            6
                                status
Review results           2      Stress                5            5
Review results           5      LIS overburdened      5            5
Instrument prep          2      Tech distracted       5            5
                                with other
                                duties
Run QC                   2      QC not properly       2            2
                                handled
Review results           2      Training              3            3
Gather work              2      Schedules not         2            2
                                followed
Instrument startup       2      Startup not done      1            1
                                property
Analyze specimens        2      Orders delayed        1            1
                                in getting to
                                analyzers

Process step/input    Current controls
What is the process   What are the existing controls
step and input under  and procedures (inspection and
investigation?        test) that prevent either the
                      cause or the failure mode?         DETECTION  RP N

Autoverification                                            5       200
Report result         Exception report                      8       144
Sample prep                                                 3       105
Shift communication                                         2        96
Review results                                              8        80
Review results                                              3        75
Instrument prep       Observation                           2        20
Run QC                SOP                                   5        20
Review results                                              2        12
Gather work                                                 2         8
Instrument startup    Checklist                             3         6
Analyze specimens                                           1         2

Figure 4. Error classification guide

Improve

Chemistry--Hitachi 747

Test Detail       Range            Review          Critical
               low    high      low     high     low      high

ALB            0.1      10.0      1.5      6.5
ALKP           3      1000        3
AMY            4      1500        4
BALKP          3      1000        3
BUN            1       150        1      130       90
CA             0.2      16.0      6.0     10.5      7.0     13.0
CHOL           3       800       30      500
CL            60       140       75      130
CO2           10        45       10       40       10       45
CPK            4      2300        4
CREAT          0.1      25.0                                 8.0
DBILI          0.1      10.0              15.0
GGT            3      1200        3
GLU            2       750       45      500       45      450
HDL            8       150       15
K              1.5      10.0      2.0      7.0      2.9      6.0
LDH            5      1000       50
MG             0.1       6.0      0.5      4.0
NA            80       180      120      155      125      155
PHOS           0.3      20.0      1.0      8.0
SGOT           4       800        4
SGPT           4       400        4
TBILI          0.1      30.0               5.0
TP             0.2      15.0      4.0      9.0
TRIG           4      1000       15      400
URIC           0.2      25.0      1.0     20.0