title: Reactive hyperemia in skin after cardiopulmonary bypass.
abstract: OBJECTIVE
  To study reactive hyperemia (RH) using a transcutaneous PO2/PCO2 combination electrode heated to 37 degrees C and tissue reflectance spectrophotometry in patients before and after cardiopulmonary bypass (CPB) to determine whether microcirculatory function of skin is altered.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Anesthesiology and critical care unit of a university hospital.
  
  
  METHODS
  Eight patients undergoing elective CPB under mild hypothermia.
  
  
  METHODS
  To produce RH, blood flow to the forearm was prevented by inflation of a cuff to 300 mmHg for an interval of 5 minutes.
  
  
  RESULTS
  Measurements were obtained on the day prior to surgery (DPS), on the day of surgery (DOS) rewarmed to 37 degrees C in the intensive care unit (ICU), and on the first (POD 1) and the third postoperative days (POD 3). The following parameters were recorded: preocclusive baseline cutaneous PO2, and PCO2 (B-PtcO2, B-PtcCO2), and microvascular hemoglobin saturation (B-HbO2); postischemic peak of PtcO2, PtcCO2, and HbO2; and 10 minutes after release of the cuff occlusion posthyperemic PtcO2, PtcCO2, and HbO2. B-PtcO2 was 3.5 +/- 1.2 mmHg on DPS, 2.6 +/- 0.7 mmHg on DOS, 1.5 +/- 0.3 mmHg on POD 1, and 3.5 +/- 3.5 mmHg on POD 3. B-PtcCO2 increased significantly from 40.1 +/- 2.5 mmHg to 52.2 +/- 2.0 mmHg on DOS (p = 0.01) and to 48.9 +/- 3.6 mmHg on POD 1 (p = 0.02). On POD 3, B-PtcCO2 was 40.6 +/- 2.6 mmHg. B-HbO2 declined from a preoperative value of 42.4% +/- 8.6% to 37.1% +/- 14.7% on DOS and further to 21.7% +/- 4.8% on POD 1, which was significantly different (p = 0.03). On POD 3, B-HbO2 still remained lower (30.7% +/- 6.2%) compared with the preoperative value. RH (deltaPtcO2, deltaHBO2) was quantified as the differences between peak PtcO2, HBO2 and B-PtcO2, B-HBO2. DeltaPtcO2 was 13.0 +/- 2.3 on DPS, 11.3 +/- 2.9 on DOS, 12.6 +/- 2.6 on POD 1, and 11.5 +/- 3.5 on POD 3. DeltaHBO2 was 42.0 +/- 5.6 on DPS, 40.0 +/- 7.1 on DOS, 49.9 +/- 2.5 on POD 1, and 52.9 +/- 6.4 on POD 3. The elimination rate of carbon dioxide from skin (ECO2) was calculated as difference between peak PtcCO2 and PtcCO2 after 3 minutes of reperfusion divided by the difference between peak PtcCO2 and B-PtcCO2. ECO2 was 1.0 +/- 0.2 kPa/min on DPS, 0.7 +/- 0.1 kPa/min on DOS, and 0.8 +/- 0.1 kPa/min on POD 1 and POD 3.
  
  
  CONCLUSIONS
  Cutaneous microcirculation assessed by RH is well preserved during the immediate postoperative period in patients undergoing uncomplicated coronary artery surgery with CPB.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University of Innsbruck, Austria.
authors.forename: E M
authors.initials: EM
authors.lastname: Gruber
authors.forename: B
authors.initials: B
authors.lastname: Schwarz
authors.forename: R
authors.initials: R
authors.lastname: Germann
authors.forename: M
authors.initials: M
authors.lastname: Breuss
authors.forename: J
authors.initials: J
authors.lastname: Bonatti
authors.forename: W
authors.initials: W
authors.lastname: Hasibeder
mesh_terms: D001785:Blood Gas Monitoring, Transcutaneous; D001831:Body Temperature / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D002315:Cardiopulmonary Bypass; D005260:Female; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology*; D007036:Hypothermia, Induced; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen