QUALITY CONTROL 1 The Importance of Accurate Results NCCLS: National Committee for Clinical Laboratory Standards NCCLS Blood gas and pH analysis has more. - презентация

1 QUALITY CONTROL 1 The Importance of Accurate Results NCCLS: National Committee for Clinical Laboratory Standards NCCLS Blood gas and pH analysis has more immediacy and potential impact on the patient care than any other laboratory determination. In blood gas analysis, an incorrect result can often be worse for the patient than no result at all. NCCLS Document C27-A, Approved Guideline, April 1993.

2 QUALITY CONTROL 2 Patient Focus Circle Quality Control

3 QUALITY CONTROL 3 What does the Quality Control System consist of? Ampoules containing liquid with similar chemical characteristics as blood Predetermined levels of pH, pO 2, pCO 2, ctHb, sO 2, FO 2 Hb, FCOHb, FMetHb, cNa +, cK +, cCa 2+, cCl -.

4 QUALITY CONTROL 4 Why Use Quality Control Tool for early error detection Alerts when maintenance is needed ? C Cal 2 Cal 1

5 QUALITY CONTROL 5 Why Use Quality Control Personal security

6 QUALITY CONTROL 6 Why Use Quality Control Documentation in writing that the analyzer is well- functioning whenever patient results are reported

7 QUALITY CONTROL 7 Why Use Quality Control Validation of analyzer performance by evaluating ­accuracy ­precision This can only be done by measuring on control materials with predetermined values ­not by duplicate testing ­not by calibration

8 QUALITY CONTROL 8 Accuracy Describes how close the measured QC value is to the true value target or true value

9 QUALITY CONTROL 9 Precision Describes the variability of repeated QC measurements target or true value

10 QUALITY CONTROL 10 QC Frequency Recommended by RADIOMETER Minimum one ampoule per shift; however, all levels should be run in one day Example: ­three shifts per day: one level per shift. The 4th level in the shift with the highest volume of patient samples ­two shifts per day: two levels per shift ­one shift per day: all levels in the one shift

11 QUALITY CONTROL 11 QC Measuring Procedure Press QC softkey 32 °C 90 °F 18 °C 64 °F Open inlet Shake for 15 sec. Aspirate the QC

12 QUALITY CONTROL 12 QC Measuring Procedure - Continued Evaluation of results Wait for results Key in ID and ampoule temperature And Close it Wipe the inlet

13 QUALITY CONTROL 13 Variations in QC Values Due to Operator Errors Ampoule was not conditioned correctly before use QC wasnt aspirated from the bottom of the ampoule Ampoule was not analyzed immediately after ampoule neck had been broken

14 QUALITY CONTROL 14 What Can Go Wrong During the QC Measurement? Ampoule is not conditioned correctly before use Ampoule is not shaken vigorously for 15 seconds Ampoule is warmed up during preparation Ampoule is not analyzed immediately after ampoule neck has been broken Ampoule storage temperature is not keyed in

15 QUALITY CONTROL 15 Conditioning of Ampoule Before Use QUALICHECK 1+, 3+, 4+, 5+ ­From refrigerator: 3 hours at °C ­Ampoule temperature has to be constant between °C 40 minutes before use Why? ­To ensure constant temperature inside the ampoule, and the same temperature as the surroundings 32 °C 90 °F 18 °C 64 °F

16 QUALITY CONTROL 16 Temperature Influence QUALICHECK is a two-phase system with gas and liquid. The equilibrium between the gas and liquid phases depend on the ampoule temperature CO 2 O2O2 O2O2

17 QUALITY CONTROL 17 Temperature Influence When temperature in the ampoule pCO 2 pO 2 - due to changed solubility between gas and liquid pH - due to change in CO 2 and H + concentration

18 QUALITY CONTROL 18 Temperature Influence Example - QUALICHECK pH pCO 2 pO °C 25 °C30 °C Difference °C Control Range

19 QUALITY CONTROL 19 Shaking of Ampoule WHY? ­To achieve full equilibrium between gas and liquid 15 sec.

20 QUALITY CONTROL 20 Avoid Heating Up the Ampoule Hold the ampoule with two fingers when shaking Errors introduced by wrong handling: ­Example: QUALICHECK Level 2, pO 2 90 mmHg ­3 fingers touching the ampoule while shaking: - 4 mmHg ­Shaking in full hand: mmHg Use the ampoule opener to break the neck of the ampoule

21 QUALITY CONTROL 21 Contamination with Atmospheric Air Example QUALICHECK 1+ Level 1 60 mmHg Level 2100 mmHg Level 3170 mmHg Level 4300 mmHg (Room air: 150 mmHg) 60 mmHg 300 mmHg Once the ampoule is open, it will be exposed to atmospheric air which will especially affect pO 2

22 QUALITY CONTROL 22 Keying In Ampoule Temperature WHY? To Correct for the difference in equilibrium at different temperatures.

23 QUALITY CONTROL 23 QC Results

24 QUALITY CONTROL 24 Evaluation of QC Results Evaluation necessary immediately after QC measurement to establish whether analyzer is well-functioning To be well-functioning the analyzer must be ­accurate:all results must fall within the defined control ranges ­precise:no trends or shifts in the plotted QC results (insert ranges only)

25 QUALITY CONTROL 25 Evaluation Procedure Recommended by RADIOMETER Insert Control Ranges (1) Verify that you have followed the recommended procedure strictly. If not, repeat the QC measurement strictly following the procedure. ACCEPTANCE STATUS Yes No Verify procedure and repeat measurement Shift/trend analysis OK Shift (1) or trend observed Yes Yes* No Perform corrective action Perform corrective action Well-functioning analyzer

26 QUALITY CONTROL 26 Shift Obvious jump between test results Indicates that the system has an intermediate problem

27 QUALITY CONTROL 27 Trend Several successive test results moving towards one of the control limits Indicates that the system is gradually going wrong

28 QUALITY CONTROL 28 Verify Procedure Did you condition ampoule correctly before use? Did you shake ampoule vigorously for 15 seconds? Did you warm up ampoule during preparation? Did you analyze ampoule immediately after breaking ampoule neck? Did you key in ampoule storage temperature?

29 QUALITY CONTROL 29 Procedure for Rejected Analyzer Do not report patient results Evaluate patient results reported since last accepted QC measurement. If necessary, notify clinicians Immediately perform troubleshooting for the parameters in question Follow instructions in troubleshooting section of analyzers operators manual or troubleshooting procedure in QC reference manual Analyzer must pass a second QC check before patient results are reported again