Clinical laboratory tests have relatively little utility in most resource-poor settings, although lives can be saved if a few simple tests are available, such as those for urine pregnancy, and in endemic/high-prevalence areas, HIV, malaria, and TB screening. This chapter discusses how to improvise various materials, equipment and tests when clinicians need lab tests and the normal procedure for doing them is unavailable.
Table 19-1 lists essential laboratory tests worldwide, which differ depending on the facility's capabilities (described in Table 5-1 in Chapter 5, Basic Equipment).
Table 19-1 Laboratory Testing Essentials |Favorite Table|Download (.pdf)
Table 19-1 Laboratory Testing Essentials
|Sickle cell prep||I||D||E||E|
|Electrolytes (Na, K, Cl, CO2, BUN, creatinine)||I||D||D||D|
|Arterial blood gas measurements||I||D||D||D|
Use filtered rainwater rather than distilled water to make laboratory reagents, such as stains. Collect rainwater in places where it won't be contaminated, such as in rooftop tanks.1 Besides laboratory use, distilled water is best for use in autoclaves and in pressure cookers used as sterilizers. If available, it should also be used to produce IV fluids.
Distillation involves boiling water and collecting the steam, which then condenses back to water. The water from condensed vapor does not contain salt and other impurities. In austere situations, improvising distillation systems saves many lives, as is seen in the following story from a World War II prison camp:2
Some six weeks before the outbreak I had constructed, as a precaution, a small plant for distilling water for intravenous saline. It was a very primitive affair, the condenser being a coiled rubber tube inside a hollow bamboo in which cold water was circulated. The boiler was a 4-gallon kerosene can. Within 24 hours of the outbreak we were able to give intravenous saline. The plant was producing 40 pints daily, and eventually double that figure. The giving IV bottle was a jam-jar connected to a needle by a rubber tube.
If distilled water is required, it can be easily obtained using a tea kettle and a collecting jar (Fig. 19-1). Heat water in the kettle and run rubber tubing from the spout through a hole in the lid of a collecting jar. Use another small tube as a vent in the jar's lid. Seal all joints with adhesive ...