Use of portable blood physiology point-of-care devices for basic and applied research on vertebrates: a review

Abstract

Non-human vertebrate blood is commonly collected and assayed for a variety of applications, including veterinary diagnostics and physiological research. Small, often non-lethal samples enable the assessment and monitoring of the physiological state and health of the individual. Traditionally, studies that rely on blood physiology have focused on captive animals or, in studies conducted in remote settings, have required the preservation and transport of samples for later analysis. In either situation, large, laboratory-bound equipment and traditional assays and analytical protocols are required. The use of point-of-care (POC) devices to measure various secondary blood physiological parameters, such as metabolites, blood gases and ions, has become increasingly popular recently, due to immediate results and their portability, which allows the freedom to study organisms in the wild. Here, we review the current uses of POC devices and their applicability to basic and applied studies on a variety of non-domesticated species. We located 79 individual studies that focused on non-domesticated vertebrates, including validation and application of POC tools. Studies focused on a wide spectrum of taxa, including mammals, birds and herptiles, although the majority of studies focused on fish, and typical variables measured included blood glucose, lactate and pH. We found that calibrations for species-specific blood physiology values are necessary, because ranges can vary within and among taxa and are sometimes outside the measurable range of the devices. In addition, although POC devices are portable and robust, most require durable cases, they are seldom waterproof/water-resistant, and factors such as humidity and temperature can affect the performance of the device. Overall, most studies concluded that POC devices are suitable alternatives to traditional laboratory devices and eliminate the need for transport of samples; however, there is a need for greater emphasis on rigorous calibration and validation of these units and appreciation of their limitations.

Keywords: Biomarkers; field physiology; hand-held blood analyser; non-domestic; validation.

Figure 1:

Whole blood values for select analytes on representative commonly studied species, the rainbow trout (Oncorhynchus mykiss) and the painted turtle (Chrysemys picta). Box plots represent the maximal ranges from the literature and horizontal lines represent the maximal reportable range of the most commonly used point-of-care device in the present study, the i-STAT analyser.

Figure 2:

Point-of-care (POC) devices can be used in the field in a variety of situations. (A) Point-of-care glucose meter being set up on a boat (photograph by Lisa Thompson). (B) Protective cases, similar to the one shown, are useful for ensuring that POC devices are not damaged by the elements (photograph by Lisa Thompson). (C) Point-of-care devices, such as this glucose meter, can be used in laboratory trials to obtain immediate results on the condition of the individual (photograph by Petra Szekeres). (D) Some POC devices, such as the i-STAT, can obtain multiple blood parameters to be measured from one sample (photograph by John Mandelman). (E) Point-of-care i-STAT device in use on a boat (photograph by John Mandelman). (F) Point-of-care pH meter in use to examine blood pH in freshwater turtles (photograph by Sarah Larocque).