Figure 40-14 Fifteen patients younger than 80 years (58 ± 10 years [mean ± SD]) shivered at 36.1°C ± 0.6°C during spinal anesthesia; in contrast, 8 patients 80 years or older (89 ± 7 years) shivered at a significantly lower mean temperature, 35.2°C ± 0.8°C. The shivering thresholds in seven of the ten patients older than 80 years was less than 35.5°C, whereas the threshold equaled or exceeded this value in all the younger patients. (Redrawn from Vassilieff N, Rosencher N, Sessler DI, Conseiller C: The shivering threshold during spinal anesthesia is reduced in the elderly. Anesthesiology 83:1162–1166, 1995.)