title: Effects of thermoregulatory vasoconstriction on pulse hemoglobin measurements using a co-oximeter in patients undergoing surgery.
abstract: OBJECTIVE
  To validate intraoperative pulse hemoglobin (SpHb) measurements in anesthetized patients with large forearm temperature - fingertip temperature gradients.
  
  
  METHODS
  prospective and observational study.
  
  
  METHODS
  Operating room of a university hospital.
  
  
  METHODS
  28 patients undergoing surgery during general anesthesia, requiring arterial blood withdrawal.
  
  
  METHODS
  Radial arterial blood pressure, forearm and fingertip skin surface temperatures, and SpHb were monitored.
  
  
  METHODS
  Paired SpHb and arterial hemoglobin (Hb) measurements at different skin-surface temperature gradients.
  
  
  RESULTS
  A total of 175 paired SpHb and arterial Hb measurements were analyzed. The mean SpHb to arterial Hb differences in each group were 0.33 ± 1.41g/dL in the < 1°C group of the forearm temperature - fingertip temperature gradient, -0.31 ± 1.24g/dL in the 1 - 2°C group, - 0.59 ± 1.11g/dL in the 2 - 3°C group, and - 0.53 ± 0.87g/dL in the > 3°C group (P < 0.05). The percentage of nonmeasurable SpHb due to low perfusion state was 0% (0 of 115 paired measurements) in the < 1°C group, 6.7% (2 of 30 pairs) in the 1 - 2°C group, 16.7% (3 of 18 pairs) in the 2 - 3°C group, and 66.7% (8 of 12 pairs) in the > 3°C group.
  
  
  CONCLUSIONS
  SpHb measured at fingertip was significantly affected by the perfusion state, with lower perfusion associated with lower SpHb. Thermoregulatory vasoconstriction affects measurement of SpHb.
authors.affiliation: Operating Rooms, Kyushu University Hospital, Fukuoka 812-8582, Japan. Electronic address: keny@fukuoka-u.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Yamaura
authors.affiliation: Department of Anesthesiology and Critical Care, Kyushu University Graduate School of Medicine, Fukuoka 812-8582, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Nanishi
authors.affiliation: Operating Rooms, Kyushu University Hospital, Fukuoka 812-8582, Japan.
authors.forename: Midoriko
authors.initials: M
authors.lastname: Higashi
authors.affiliation: Department of Anesthesiology and Critical Care, Kyushu University Graduate School of Medicine, Fukuoka 812-8582, Japan.
authors.forename: Sumio
authors.initials: S
authors.lastname: Hoka
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000379:methods; D005260:Female; D005385:Fingers / Q000098:blood supply; D005542:Forearm / Q000098:blood supply; D006454:Hemoglobins / Q000032:analysis*; D006785:Hospitals, University; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D010092:Oximetry / Q000379:methods*; D011446:Prospective Studies; D012881:Skin Temperature / Q000502:physiology*; D014661:Vasoconstriction / Q000502:physiology*
chemical_list: D006454:Hemoglobins
keywords: Hemoglobin: noninvasive, SpHb; Peripheral perfusion; Pulse co-oximetry