BACKGROUND: In order to conserve blood and keep the operating field clean, cell saver is often used with electrocautery in hip arthroplasty. When applying the principle of thermal coagulation, electrocautery produces tissue self-burning with noxious gas byproducts, including carbon monoxide(CO). However the existing blood salvage systems do not have any reoxygenation or filtration function for CO.OBJECTIVE: To evaluate the effects of simultaneous use of electrocautery and a cell saver system on the blood levels of CO in patients undergoing hip arthroplasty.DESIGN: A comparative observation.SETTING: Department of Orthopedics, Duisburg-Essen University.PARTICIPANTS: From August 2002 to August 2003, patients undergoing hip arthroplasty including the use of electrocautery as well as intended use of a cell saver system were selected from the Department of Orthopedics, Duisburg-Essen University. Exclusive criteria: ① smoking history; ② history of anemia, hemoglobinopathy or coagulopathy; ③history of organ dysfunction, including lung, liver and kidney; ④ preoperative abnormal electrocardiogram (ECG), including cardiac ischemia and/or arrhythmia.Among all the enrolled patients, those who ultimately received the retransfusion of processed salvaged blood were counted as the observed group,whereas the others who did not receive any retransfusion for inadequate salvaged volume or possible contamination within salvaging were added as the control group, and no allogenic blood was transfused. All the patients agreed to participate in the study.METHODS: ① All the operations were performed under combined intravenous and inhalation general anesthesia. ② Electrocautery was used for coaluation during the incision of subcutaneous tissues, fascias, muscles as well as capsules. ③ A cell saver system (Haemonetics Cell Saver #5 System, manufactured by Haemonetics Corporation, U.S.A.) was applied during the operation. Salvaged blood were retransfused into the patients after the procedure of filtration and wash. ④ Blood CO-Oximetry: Blood CO levels were measured by carboxyhemoglobin (CO-Hb) concentration with a spectrophotometric blood gas analyzer (ABL 700 series, manufactured by Radiometer, Copenhagen, Denmark). In both groups, systemic blood samples were collected from a radial arterial catheter at 3 time points, including preoperatively, postoperatively and merely before the retransfusion of salvaged blood and at 6 hours postoperatively. In the observed group, additionally samples were collected instantly after skin incision from the aspirator connected to the cell saver reservoir, directly after femoral stem implantation also from the aspirator and immediately before retransfusion from the collecting sac, to reveal the trend of CO-Hb levels in salvaged blood.MAIN OUTCOMEMEASURES: CO-Hb levels in the systemic blood and salvaged blood at different time points were mainly observed.RESULTS: Totally 49 patients were involved in the analysis of results. ① General data: Forty-nine ASA Ⅰ -Ⅱ patients were enrolled in this study.There were 35 and 14 patients in the observed and control group, respectively, with 7 and 3 had a history of coronary heart diseases (heart function of class Ⅰ - Ⅱ ) correspondingly. There were no obvious differences in the sex, age, mean operative time and mean estimated blood loss between the two groups (P ＞ 0.05). The vital signs were stable in all the patients. ② CO-Hb concentration: In the observed group, the CO-Hb concentration in systemic blood at 6 hours postoperatively was significantly increased as compared with the preoperative and postoperative ones [(2.2±0.54)%,(1.6±0.34)%, (1.7±0.19)%, P ＜ 0.05]; the CO-Hb concentration in salvaged blood was (2.6±0.62)%, which was significantly higher than that in systemic blood preoperatively and postoperatively (P ＜ 0.01). In the control group, the CO-Hb concentration in systemic blood at 6 hours postoperatively had no obvious differences as compared with the preoperative and postoperative ones (P ＞ 0.05). ③ Postoperative conditions: In the observed group, sinus tachycardia and inferior myocardial ischemia were detected by ECG monitoring in 2 patients with pre-existing coronary heart disease,which complained of precardial discomfort at 4-6 hours postoperatively.Higher levels of CO-Hb were detected in salvaged blood before retransfusion (39% and 4.5%) and in systemic blood at 6 hours postoperatively(3.5% and 4.2%). No patient in the control group demonstrated symptoms of CO intoxication or cardiovascular compromise, also no abnormal changes were revealed by ECG monitoring.CONCLUSION: Retransfusion of salvaged blood in hip arthroplasty with simultaneous use of electrocautery and a cell saver system leads to a significant increase of systemic CO-Hb concentration, which can provoke the cardiovascular compromise. Therefore, it is suggested to measure CO-Hb level in salvaged blood, the retransfusion of which should be cautious, especially to patients with pre-existing heart diseases.