Laser Assisted
Optical Rotational Cell Analyzer
 
 
The Lorca is a new version of the earlier announced LORD (Laser-assisted Optical Rotational Deformability meter) especially developed for this measurement at the Academic Medical Center (AMC) in Amsterdam, the Netherlands. The applicability of the instrument has now been extended and tested for RBC-aggregation both regarding the syllectogram and quantitative parameters like aggregation index, aggregation at low shear, minimal shear rate to prevent aggregation, kinetic characteristics, etc. Since further additional modules may be added in the near future, the name of the instrument has been changed into LORCA (Laser-assisted Optical Rotational Cell Analyzer).
 
   

The LORCA features are:

  • A versatile system for full computerized control, measurement and calculation of: erythrocyte deformability, and erythrocyte aggregation.
  • Only 25 ul blood needed for each deformability measurement.
  • Easy sample changing
  • Full control by IBM compatible computer
  • 4 mW laserdiode in shielded setup for maximum user safety
  • Adjustable shear rates from 0 - 3500 s-1.
  • On-line data analyses and storage via digital camera system
  • "On screen" control of diffraction pattern
  • Temperature controlled
 
 

Application fields
Research laboratory
Proven accuracy in comparison with other apparatus regarding normal values, heat treatment and cell age(1)(2).

Clinical laboratory
The clinical importance of erythrocyte deformability has recently been reviewed(3).
Relevant clinical results are reported e.g. patients with diabetes, uremia, sickle cell anemia(2) and hereditary spherocytosis(4).
Influence of anaesthetics(5), contrast media(6) and cyclosporin(7).

 

Principle of operation
Cell deformability

A thin layer of red blood cell suspension is sheared between two concentric cylinders. The rotation of the outer cylinder (cup), causes deformation (elongation) of
the red blood cells. The laserbeam diffraction pattern is detected with a video camera and analyzed by a computer.

Cell aggregation
Various aggregation indices are determined in whole blood by means of reflection measurements. A laserdiode, mounted in the bob, serves as light source. The reflected light is sensed by a photodiode.
 
       
 
     
 
(1) RBC Laserdifractometry and RBC Aggregation with a rotational Viscometer: Comparison with Rheoscope and Myrenne aggrometer. M.R. Hardeman, R.M. Bauersachs, H.J. Meiselman. Clin. Hemorheol., 8 (1988) 581-593.
(2) Laserdiffraction Ellipsometry of erythrocytes under shear stress using a rotational viscosimeter. M.R. Hardeman, P.T. Goedhart, D. Breederveld, Clin. Chim. Acta 165 (1987) 227-234.
(3) The clinical importance of erythrocyte deformability, a hemorheological parameter. F. Ch. Mokken, M. Kedaria, Ch.P. Henny et al. Ann. Hematology 64 (1992) 113-122.
 
 
 
(4) Some characteristics of the erythrocytes in hereditary spherocytosis P.W. Wijermans, M.R. Hardeman. Clin. Hemorheol. 7:3 (1987)(5) The effects of propofol compared to high-dose fentanyl anesthesia on rheologic parameters in coronary artery surgery. F. Ch. Mokken, Ch. P. Henny, A.W. Gelb, J.D. Biervliet, M.R. Hardeman, M. Kedaria and Vasc. Anesthes. 7 (1993) 10-16.
(6) Interrelationship of changes in hemorheological parameters induced by low osmolar radiocontrast media. M.R. Hardeman, P.T. Goedhart. Clin. Hemorheol 12 (1992) 381-392.
 
       
       
(7) Decrease of erythrocyte deformability in cyclosporin-treated renal transplant patients: correction with fish oli as well as corn oil. N.H. Schut, M.R. Hardeman, J.M. Wilmink, Transplant Int. 5 (1992, supl. 1) S536-538).
(8) Laser assisted Optical Rotational Cell Analyser. (L.O.R.C.A.) A new instrument for measurement of various structural hemorheological parameters: M.R. Hardeman, P.T. Goedhart, J.G.G. Dobbe, K.P. Lettinga. Clin. Hemorheol. Vol. 14, No. 4 (1994) 605-618.
(9) Laser assisted Optical Rotational Cell Analyser. (L.O.R.C.A.) Red blood cell deformability: Elongation index versus cell transit time. M.R. Hardeman, P.T. Goedhart, N.H. Schut. Clin. Hemorheol Vol. 14, No. 4 (1994) 619-630)
 
 
Design and specifications subject to alteration without notice.
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