Research on human adaptation to microgravity often involves storing blood samples for later analysis on Earth. Immediate, inflight analysis would make results available during a mission and would avoid the need for refrigeration or freezing and the possibility of deterioration of the samples. The objective of this hardware study was to test a portable device for inflight analysis of blood samples.
The Portable Clinical Blood Analyzer (PCBA) is a hand-held, battery-powered device that measures electrolytes by ion-selective electrode potentiometry, glucose by amperometry, hematocrit by conductometrics, and pH by direct potentiometry. It does not measure hemoglobin. The analyzer was tested on the ground against traditional laboratory methods, using capillary blood, venous blood and control solutions. It was then tested for inflight use on 5 Shuttle missions. Control solutions were analyzed before and during the flights. Twice during flight, 21 astronauts performed finger sticks on each other, collected capillary blood using heparinized capillary tubes, and transferred the blood to the analyzer. Blood samples were also collected and analyzed before and after flights.
The performance of the analyzer in microgravity was similar to its performance on the ground for all the control solutions except sodium, and the small difference in sodium levels was within clinical laboratory performance standards. The astronauts were able to collect and analyze blood samples in flight. Some changes were noted in pH and levels of potassium and ionized calcium during flight or on landing day, but the values returned to preflight levels within 3 to 6 days. The analyzer was found to be very reliable for immediate analysis of sodium, potassium, ionized calcium, pH and glucose on the ground and during space flight. It is being flown routinely to help flight surgeons evaluate the health of the astronauts, and it will be especially useful for following calcium levels and evaluating bone changes during long spaceflights. The device may also prove useful in remote areas on Earth.