Fig 1.
Overview of the rHEALTH method for microvolume cytometry analysis of platelets and data from benchmark cytometer and rHEALTH.
A. Left, 8 μl capillary blood sample in a clear plastic consumable is loaded into the instrument for analysis. Middle, The sample consumable is received by a plunger-based, in-line sample loader which seals around its two open ends. Pressure (~ 70 mbar) is applied to the system which drives the entire sample volume, via hydrodynamic focusing, into a miniaturized optical module for laser-based cytometry detection. A fluidics module with electronic valves manages fluids from the pressurized sheath and clean bottles (60 cc). The analyzed sample passes through the optical block and into the removable waste bottle (60 cc). The electronics with embedded software manage instrument control and data capture. Dashed lines indicate connection to the optical and fluidics modules. Arrows from the electronics module indicate a control function and arrows to the electronics indicate a data function. The USB provides power, control commands, and data output to and from a PC. Right, The device is shown in its side view with dimensions, mass, USB 2.0 port, and sample loading orientation. A PC computer (not shown) provides power (up to 2.5W) via the USB connection, collects raw data, and performs data analysis. B. XY scattergraphs generated by Coulter cytometer in quadrant analysis. C. rHEALTH histogram analysis of total platelet count includes all orange fluorescent events.
Fig 2.
Performance of rHEALTH and Coulter ISLH for fingerstick and venous samples.
Plot of rHEALTH absolute volumetric PLT counts versus Coulter ISLH for (A) fingerprick samples and (B) venous samples. Plot of venous platelet counts versus fingerprick platelet counts using Coulter ISLH and the rHEALTH absolute volumetric PLT for (C) rHEALTH and (D) Coulter. Platelet concentrations for all are in plt/μL and the trend line equation and R2 are shown.
Fig 3.
Correlation plot of Coulter ISLH venous platelet counts versus rHEALTH fingerprick platelet counts using absolute volumetric method.
Platelet concentrations for both are in plt/μL and the trend line equation and R2 are shown.
Fig 4.
Bland-Altman analysis of the rHEALTH absolute volumetric approach versus Coulter ISLH.
The bias is shown with +/- 1.96 SD bounds. (A) Fingerprick samples for both approaches, (B) Venous samples for both approaches, and (C) Bland-Altman of Coulter ISLH venous versus rHEALTH fingerstick analysis.
Fig 5.
Graphical analysis of the ABX, Coulter ISLH, and rHEALTH precision data.
The effect on platelet counts precision (N = 16 per condition). The precision for ABX Micros 60 at 2.2–18.7%, Coulter ISLH at 1.0–15.9 and the rHEALTH at 3.1–37.5% for all samples. Excluding the anti-platelet antibodies, which yielded close to zero counts via Coulter ISLH and the rHEALTH, the precision for non-zero platelet counts, indicated in the boxed area,was as follows: ABX Micros 60 at 4.5–18.7%, Coulter ISLH at 1.0–10.5 and the rHEALTH at 3.1–8.0%.
Table 1.
% of expected PLT concentration with interferents.