The effect of induced hypotension on the perioperative bleeding and transfusion in the bipolar hemiarthroplasty of hip: retrospective study for four years

provided the original work is properly cited. CC It is well known that induced hypotensive anesthesia results in reduced blood loss and allows for a cleaner surgical field intraoperatively, leading to improved visualization. We investigated the effect of induced hypotensive anesthesia compared to that of normotensive anesthesia on blood loss and found that induced hypotension can reduce the volume of transfusion during the hospitalization period in bipolar hemiarthroplasty (BPHA) of the hip. We retrospectively reviewed the anesthetic records, nursing notes, and hematologic laboratory data. We divided the patients into two groups, with patients who underwent surgery from January 2008 to December 2009 placed in the control group, while patients who received surgery between January 2011 and July 2012 were placed in the experimental group. We excluded patients who received surgery in the year of 2010 to diminish bias because we did not have a standardized protocol for induced hypotension anesthesia during that year. In addition, all operations were performed by a single orthopedic hip expert who had been operating for twenty-five years. Patients in both groups received three types of anesthesia: spinal, epidural, and general anesthesia. Normotensive anesthesia was administered with the maintenance of mean arterial pressure (MAP) between 70-80 mmHg without considering intraoperative induced hypotension. In the experimental group, however, anesthesia was administered by a single orthopedic anesthesia specialist according to his protocol for induced hypotension. The goal of induced hypotension was maintenance of MAP between 55-60 mmHg. When an adjunct was necessary, nicardipine 2-5 mg/hr was infused continuously. Values of MAP < 55 mmHg were treated with intravenous fluids, ephedrine, and phenylephrine therapy. We collected data on operation time, blood loss, Hemoglobin (Hb), Hematocrit (Hct), and transfusions. Intraoperative blood loss was measured by the anesthesiologist based on the contents of suction bottles and the increase in weight of surgical swabs. Blood loss in the postoperative period was estimated from the volume in the drainage bags. Postoperative Hb and Hct were measured three days after the surgery. SPSS 14.0 was used for statistical analysis (SPSS Inc. Released 2006. SPSS for Windows, Version 14.0. Chicago, IL, USA). Continuous values were analyzed using the Z-test, and binary values using the chi-square test. Null hypotheses were rejected if P values were less than 0.05. Demographic and perioperative data for the two groups are shown in Table 1. Many studies have been performed which measured intraoperative blood loss in total hip replacement arthroplasty (THRA), but there has been no specific study to date which measured the blood loss in BPHA. The effect of an intervention designed to reduce blood loss would be expected to be similar in BPHA and in THRA, however, as the two procedures are not significantly different. Among patients undergoing THRA, the group with induced hypotension experienced a blood loss volume during surgery of approximately 300-400 ml, which was significantly lower than the blood loss volume during surgery for the group