Fig. 18. Fifteen patients aged younger than 80 yr (58 ± 10 yr) shivered at 36.1°± 0.6°C during spinal anesthesia; in contrast, eight patients aged 80 yr or older (89 ± 7 yr) shivered at a significantly lower mean temperature, 35.2°± 0.8°C. The shivering thresholds in five of the eight patients aged older than 80 yr was less than 35.5°C, whereas the threshold equaled or exceeded this value in all the younger patients. Results are presented as mean ± SD. From Vassilieff  et al. 85; used with permission. Copyright © 1995, the American Society of Anesthesiologists, Inc. and Lippincott Williams & Wilkins.