title: Effect of pain on autonomic nervous system indices derived from photoplethysmography in healthy volunteers.
abstract: BACKGROUND
  Photoplethysmographic pulse wave amplitude (PPGA) and heart rate (HR) can be used to measure cold, nociception-induced autonomic responses, or both. The aim of our study was to correlate the intensity of experimental pain to changes in physiological variables reflecting the autonomic nervous system response to pain.
  
  
  METHODS
  PPGA, HR, and subjective measurements of pain intensity were measured in 29 healthy male volunteers during two heat stimuli (43°C and 48°C) and the cold pressor test (CPT). Surgical pleth index (SPI), autonomic nervous system state (ANSS), and ANSS index (ANSSi) were calculated using PPGA and HR.
  
  
  RESULTS
  Pain intensity scores increased on the average by 1.6, 3.5, and 8.1 for the 43°C, 48°C, and CPT stimuli, respectively. The pain intensity scores for all three stimuli groups were significantly different from each other (P<0.001). All three stimuli changed HR, PPGA, SPI, ANSS, and ANSSi values significantly from their respective baseline values (P<0.001 for all). Heat stimuli-induced pain intensity did not correlate with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. CPT-induced pain intensity correlated with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. PPGA, ANSSi, ANSS, and SPI differentiated between heat and cold stimuli-induced pain.
  
  
  CONCLUSIONS
  All three thermal stimuli produced a significant change in photoplethysmograph-derived parameters. All photoplethysmograph-derived parameters appear to be suitable to study autonomic nervous system activation.
authors.affiliation: Pain Clinic, Department of Anaesthesia and Intensive Care, Helsinki University Central Hospital, PO Box 140, Helsinki FIN-00029 HUS, Finland. katri.hamunen@hus.fi
authors.forename: K
authors.initials: K
authors.lastname: Hamunen
authors.forename: V
authors.initials: V
authors.lastname: Kontinen
authors.forename: E
authors.initials: E
authors.lastname: Hakala
authors.forename: P
authors.initials: P
authors.lastname: Talke
authors.forename: M
authors.initials: M
authors.lastname: Paloheimo
authors.forename: E
authors.initials: E
authors.lastname: Kalso
mesh_terms: D000293:Adolescent; D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D003080:Cold Temperature; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010146:Pain / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D017156:Photoplethysmography / Q000379:methods; D055815:Young Adult