A comparison of simple tests to distinguish cerebrospinal fluid from saline

Purpose: This prospective study was undertaken to determine if anesthesiologists of different levels of training, using simple tests, can distinguish cerebrospinal fluid (CSF) from saline. Methods: Thirty-two anaesthetists, divided into four groups, dependent upon levels of training, participated in the study, Each was asked to distinguish saline from an artificial CSF solution using four different tests: tactile temperature, glucose strip, pH strip, and turbidity when mixed with thiopental. Results: Participants identified cerebrospinal fluid correctly with 84% accuracy using the temperature test, 97%, using the glucose test, 91% using the pH test, and 50% using the thiopentone test. More than half of the participants guessed while using the thiopentone test, and those who did not guess were only 47% accurate. Conclusion: Level of training made no difference in distinguishing CSF from saline. No one test was 100% reliable. Clinical utility of the thiopentone test appears to be limited. The temperature, glucose, and pH tests, when used together, appear to be a useful way of distinguishing CSF from saline.