Fig. 4. Effects of temperature and concentration on the density of hyperbaric bupivacaine. Depicted are all measurements at least in triplicate per concentration at 5°, 20°, 30°, and 37°C and polynomial curve fits ( P and R 2given in table 3 ). Note extended scale of y-axis versus all other figures. Hyperbaric (hyper) bupivacaine, 2.5 and 5 mg/ml as commercially available solutions. Horizontal line = cerebrospinal fluid (CSF) (n = 7) at 37°C; gray bar = 3-SD range.