T . Matsumoto et al .: J Extra Corpor Technol 2023 , 55 , 167 – 174 169
( a )
( b )
Figure
1 . Photograph of test circuit . The test circuit was a closed circuit consisting of an ultrafiltration membrane ( BIOCUBE Hemoconcentrator BHC-110 ; NIPRO Co , Ltd ., Osaka , Japan ) and a medical soft bag connected by a vinyl chloride tube . The open-air circuit ( 3.3 mm i . d .) and filtrate circuit ( 6 mm i . d .) in the blood circuit were fixed vertically side-by-side .
to 0.74 mmHg ( hereinafter referred to as “ test method ”). To obtain comparative values , measurements were performed using a colloid osmometer to measure simultaneously collected samples . Samples were collected from the sampling port of the circuit ( Figure 2b , # 2 ). For re-measurement , the process was repeated from the pre-measurement preparation state .
Experiment 1
The bovine blood in the circuit was concentrated using ultrafiltration , and seven concentrations were prepared as test liquids 1 – 7 . The concentration of each test liquid was determined by measuring the hematocrit ( Hct ) value three times using a blood gas analyzer ( ABL800 ; Radiometer Corporation , Tokyo , Japan ), and calculating the mean value .
For each test liquid , COP was measured 10 times both by the test method and with samples for comparison . For each COP measurement , the circuit was returned to its pre-measurement preparation state , blood was circulated for 5 min , the standby time began , and the next measurement was performed . After the COP of test liquid 1 was measured 10 times with both methods , the blood in the circuit was concentrated to prepare test liquid 2 , and the COP was subsequently measured 10 times with both methods . The same procedure was continuously repeated to conduct measurements up to test liquid 7 ( Figure 3 ). Therefore , except for the first test liquid , all test liquids were prepared within the circuit .
To impose a load on the ultrafiltration membrane , ultrafiltration was performed slowly for over 30 min to prepare the test
Figure 2 . ( a ) Test circuit diagram ( blood circulation before measurement ). The atmospheric release circuit of the blood circuit must be emptied . The filtrate level was set at the height of the threeway stopcock for blood circuit switching , the filtration circuit was closed . The blood circuit was cycled for more than 5 min . ( b ) Test circuit diagram ( during colloid osmotic pressure measurement ). The roller pump was stopped , the three-way stopcock was switched , and the blood circuit was switched to an open-air circuit . The clamp of the filtrate circuit was then opened to expose the circuit to the atmosphere . After waiting 3 min for the solvent migration in the blood and filtrate circuits to equilibrate , the water level difference created between the two circuits was measured .
liquid . In addition , the blood flow rate during the preparation of the test liquid was varied . Starting with test liquid 1 ( 100 mL / min ) and test liquid 2 ( 150 mL / min ), the rate was increased by 50 mL / min for each test liquid up to test liquid 7 ( 400 mL / min ).
Experiment 2
Three types of test liquid were used ( test liquids 8 – 10 ). Test liquid 8 was bovine blood , prepared using the same technique as used in Experiment 1 , and the concentration was determined based on Hct . Test liquid 9 was prepared by adding 150 mL of aqueous albumin solution to test liquid 8 , and then concentrated by removing 150 mL of water using filtration . Test liquid 10 was obtained by adding 100 mL of albumin solution to test liquid 9 , removing 100 mL of water by filtration , and concentrating the resulting solution . The aqueous albumin solution was prepared by dissolving albumin powder ( FUJIFILM Wako Pure Chemical Corporation , Osaka , Japan ) in a physiological saline