PRINSIP DASAR PEMERIKSAAN AGGREGOMETER

(PLATELET AGGREGATION TEST)

PLATELET AGGREGATION TEST

Digunakan untuk evaluasi kemampuan trombosit untuk membentuk agregat/clump dan mengawali terbentuknya bekuan darah.

Indikasi :• Diagnosis gangguan fungsi trombosit kongenital (von willebrand’s

disease) maupun yang didapat, pada pasien riwayat perdarahan.• Dugaan peningkatan agregasi trombosit( DM, Hiperlipidemia)• Monitoring terapi anti-trombosit (aspirin, ticlopidine, clopidogrel,

abciximab) pasca stroke atau heart attack.• Deteksi faktor resiko trombosis arteri.

PLATELET AGGREGATION TEST

(sambungan)

• Deteksi resistensi aspirin• Monitoring fungsi trombosit selama operasi CABG, kateteasi

jantung, transplantasi hepar.• Skrining pasien preoperasi beresiko perdarahan selama

prosedur invasif.

PLATELET AGGREGATION TEST

2 METODE• Turbidimetric measurements –

LightTransmittance Aggregometry (LTA) Platelet Rich Plasma

• Impedance Agregometry Whole Blood

Turbidimetric measurements – LightTransmittance Aggregometry (LTA)

Prinsip pemeriksaan adalah perubahan transmisi cahaya (light transmittance changes).

PRP yg keruh ditempatkan di dalam cuvet, kemudian diinkubasi pada suhu 37 C pada blok pemanas dalam instrumen, dan diaduk dengan bar magnetik, transmisi cahaya yg melalui PRP di catat sebagai baseline.

Penambahan agonist (aggregating agents) ke dalam PRP akan menginduksi terjadinya agregasi trombosit sehingga transmisi cahaya melalui PRP meningkat .

Perubahan pada transmisi cahaya akan di konversikan ke sinyal listrik, dan direkam membentuk grafik.

Turbidimetric measurements – LightTransmittance Aggregometry (LTA)

Light transmittance aggregometry (Born’s method)

Transmitted light

PRP

Transmitted light 100%

70% Transmitted

light

Platelet aggregates

0%

PPP

AGGREGATION AGONISTS

Arachidonic acid Thrombin ADP (sering digunakan)

Epinephrine Collagen Ristocetin

http://www.platelet-research.org/3/aggregometry.htm

•Optical Aggregation in Platelet-Rich-Plasma

SPECIMEN PREPARATION

Specimen : plasma obtained from whole blood colected with 3.2% sodium citrate as an anticoagulant is the specimen of choice

Prepare Platetet Rich Plasma (PRP) by centrifuging the anticoagulated samples at 100 x g 10 -15 minutes at room temperature.

Prepare platelet poor plasma (PPP) by centrifuging at 1600-2000 x g for 10 -15 minutes at room temperature

Impedance Agregometry Whole Blood

Whole blood is diluted in saline to form a suspension. Parallel electrodes coated with collagen are immersed in the suspension and a small current applied. As platelets aggregate in response to the addition of an agonist,they collect on the surface of the electrode, thereby altering the strength of the current.

The change in current is measured by the aggregometer, converted to electronic signals and recorded on the chart in a tracing similar to that seen with platelet-rich plasma aggregation

Impedance Agregometry Whole Blood

TROUBLE SHOOTING

Masalah pada uji agregasi trombosit sering timbul akibat : Preparasi sampel yang salah. Intstrument yg tidak dikalibrasi secara rutin.

MEDICATION THAT MAY AFFECT PLATELET AGGREGATION

Antibiotics that have a ᵦ-lactam ring Penicilin, chepalosporins

Diyridamole Fibrinolytics Dextran Anesthetics lidocaine, dibucaine, cocaine, etc Trombin inhibitor heparin Thienopyridines GPIIb-IIIa Antagonis

TERIMAKASIH