Table 1.
Experimental design, specimens used, laboratory analysis conducted, findings, and conclusions from the measurement of hemoglobin using the HemoCue® Hb-201+ and/or Hb-301 analyzers1
| Experiment | Design | Specimens | Laboratory analysis | Finding | Conclusion |
|---|---|---|---|---|---|
| Comparability of HemoCue® models, including supplies and operation | |||||
| 1. HemoCue® model comparability | Test multiple analyzers of 2 HemoCue® models | Venous EDTA blood (n = 25) from TNBS donors | Hb-201+ (2 analyzers, 1 reading/analyzer) Hb-301 (12 analyzers, 1 reading/analyzer) |
Hb-301 measured 2.6% higher than Hb-201+ | Results from Hb-201+ and Hb-301 are not comparable |
| 2. Cuvette lot-to-lot variability | Test multiple cuvette lots for 2 HemoCue® models | Venous EDTA blood (n = 25) from TNBS donors | Hb-201+ (2 lots, 1 reading/lot) Hb-301 (3 lots, 1 reading/lot) |
Low variability for both HemoCue® models (CV = 1%) | Cuvette lot variability is acceptable |
| 3. Delayed Hb reading | Read Hb at 0 (reference), 1, 2, 3, 4, 5, and 6 min after filling the cuvette | Venous EDTA blood (n = 10) from TNBS donors | Hb-201+ (1 reading) Hb-301 (1 reading) |
Hb-201+ showed comparable results up to 6 min Hb-301 showed increasing results (1.3% per min) |
Reading on Hb-301 must be carried out within 1 min of filling the cuvette |
| Robustness of HemoCue® analyzers and supplies | |||||
| 4. Exposure of analyzers or supplies to elevated temperature | a. Keep analyzers at 37°C (incubator) for up to 3 wk and test weekly (reference: 0 wk) | Controls (level 1, 2, and 3) for each model | Hb-201+ (2 analyzers, 2 readings/analyzer) Hb-301 (2 analyzers, 2 readings/analyzer) |
Keeping analyzers (both models) at 37°C for up to 3 wk did not affect results by more than ±1% | Analyzers for both HemoCue® models can withstand elevated temperature |
| b. Keep cuvettes at 37°C (incubator) for up to 3 wk and test weekly (reference: 0 wk) | Venous EDTA blood (n = 24) from TNBS donors | Hb-201+ (2 readings) Hb-301 (2 readings) |
Keeping cuvettes (both models) at 37°C for up to 3 wk did not affect results by more than ±1% | Cuvettes for both HemoCue® models can withstand elevated temperature | |
| c. Keep Hb-301 controls at 32°C (incubator) for up to 3 wk and test weekly (reference: 0 wk) | Controls (level 1, 2, and 3) | Hb-301 (2 analyzers, 1 reading/analyzer) | Keeping controls (Hb-301) at 32°C for up to 3 wk did not affect results by more than ±1% | Controls for the Hb-301 can withstand elevated temperature | |
| 5. Exposure of cuvettes to elevated temperature and humidity | a. Keep cuvettes (Hb-301) at 37°C/72% humidity (incubator) in either closed or open boxes for up to 3 wk and test at 0 (reference), 1, 8, 15, and 21 d | Controls (level 1, 2, and 3) | Hb-301 (2 readings) | Keeping cuvettes for Hb-301 (closed or open box) at 37°C and 72% humidity for up to 3 wk did not affect results | Cuvettes for Hb-301 can withstand elevated temperature and humidity for several weeks |
| b. Keep cuvettes (Hb-201+) at 37°C/72% humidity (incubator) in closed boxes for up to 3 wk and test at 0 (reference), 1, 8, 15, and 21 d | Controls (level 1, 2, and 3) | Hb-201+ (2 readings) | Keeping cuvettes for Hb-201+ (closed box) at 37°C and 72% humidity for up to 3 wk did not affect results | Cuvettes for Hb-201+ must be stored in the tightly closed box | |
| c. Keep cuvettes (Hb-201+) at 37°C/72% humidity in open boxes for up to 1 h and test at 0 (reference), 10, 20, 25, 30, 40, and 60 min | Controls (level 1, 2, and 3) | Hb-201+ (2 readings) | Keeping cuvettes for Hb-201+ (open box) at 37°C and 72% humidity for up to 1 h produced significantly lower results after 10 min compared to 0 min | Cuvettes for Hb-201+, when exposed to humidity, they degrade within 10 min | |
| Venous vs. capillary blood samples | |||||
| 6. Comparability of venous and capillary blood | Measure paired venous and capillary blood samples | Venous and capillary EDTA blood (n = 33) from CDC donors | Hb-201+ (3 readings) | Hb-201+ produced slightly higher results for capillary blood samples, but the difference was not significant | In apparently healthy individuals, venous and capillary blood samples produce comparable results when sampled by an experienced technician |
| 7. Comparability of individual drops vs. pooled capillary blood | Measure 2nd, 3rd, and 4th drop capillary blood and compare to pooled capillary blood from Microtainer™ | Capillary EDTA blood (n = 32) from CDC donors | Hb-201+ (1 reading) | Hb-201 produced comparable results for second or third drop relative to pooled blood; however, fourth drop produced significantly lower results by 3.2% | Individual drops of blood (second and third) and pooled blood produce comparable results when sampled by an experienced technician |
| Sample storage and freeze-thawing | |||||
| 8. Storing blood at different temperatures for up to 4 d | Store venous blood at 10°C, room temperature, and 30°C (incubator) for up to 4 d and test daily (reference: 0 d) | Venous EDTA blood (n = 24) from TNBS donors | Hb-201+ (2 analyzers) Hb-301 (2 analyzers) |
Hb-201+ produced comparable results at each temperature and day Hb-301 produced increasing results with time and temperature; storage of blood for more than 1 d at higher than ambient temperature resulted in >1% increase |
When using Hb-201+, blood can be stored for a few days prior to measurement at a wide range of temperatures (10–30°C) When using Hb-301, blood can to be stored at ambient or refrigerated temperature for maximum 1 d prior to measurement |
| 9. Freeze-thawing | a. Freeze capillary blood at −70°C for 4 d and compare to result obtained with fresh blood | Capillary EDTA blood (n = 32) from CDC donors | Hb-201+ (2 readings) | Hb-201+ produced slightly lower results (1.7%) in thawed compared to fresh blood samples | Hb should be measured in fresh samples; Hb measured in thawed samples is no longer accurate |
| b. Freeze venous blood at −70°C, conduct 1 freeze-thawing cycle on day 1 and a second freeze-thawing cycle on day 2 and compare to result obtained with fresh blood | Venous EDTA blood (n = 25) from TNBS donors | Hb-201+ (2 analyzers) Hb-301 (2 analyzers) |
Hb-201+ produced slightly lower results after 1 (1.8%) and 2 (1.6%) freeze-thawing cycles compared to fresh blood samples Hb-301 produced slightly higher results after 1 (1.6%) and 2 (2.1%) freeze-thawing cycles compared to fresh blood samples |
Hb should be measured in fresh samples; Hb measured in thawed samples is no longer accurate | |
1
Hb, hemoglobin; TNBS, Tennessee Blood Services