Real-Time Non-Invasive Blood Monitor Could Cut Transfusions During Surgery
New non-invasive continuous monitoring of blood can reduce the number of transfusions given during surgery, according to the results of a small clinical trial presented at the conference in the U.S. on Monday.
Report of the trial, presented at the American Society of Anesthesiologists annual meeting in San Diego on October 18 showed that using only conventional laboratory tests for measuring hemoglobin levels during surgery as a result of 4.5% of patients to blood transfusion during their work, compared with only 0.6%, whose red blood cell levels were also measured with noninvasive "real time" monitor.
As well as increasing the duration of stay in hospital having a blood transfusion during surgery may increase the risks for patients, such as the likelihood of postoperative infections, the likelihood of recurrence of cancer, and lung function, says Jesse Ehrenfeld, director of the Center for Evidence-Anesthesia at Vanderbilt University Medical Center, in Nashville, Tennessee, who led the trial.
Thus, although it would be better for patients and also helps maintain a national pool of blood in order to avoid unnecessary blood transfusions, a challenge that surgical teams face when the patient begins to bleed during surgery is an accurate assessment of how much blood lost, and whether the patient has enough red blood cells or hemoglobin on the left to complete the procedure without blood transfusions.
Current methods are based on observation and laboratory tests that can be done only intermittently, and can take anywhere from 15 to 45 minutes to return to the surgical team, so that in the absence of timely results, surgeons often go to the safe option, contributing 1.9 million transfusions given during surgery each year in the United States.
This issue is contested by companies such as Masimo Corp, Irvine, Calfornia, to come up with new technology, known as a continuous and noninvasive hemoglobin (Hb) monitoring, which they call "SpHb monitoring" that calculates the surgical patients' red blood cell levels continuously in the mode of real-time, that is, as it happens, and without delay, and it also does it without puncturing the skin.
Monitor SpHb that Ehrenfeld and his team tested in randomized prospective controlled study for 6 months was Masimo Radical-7 Pulse CO-Oximeter and the R1-25 Rainbow adhesive sensor version E unit.
The device measures the level of hemoglobin using near-infrared light of different wavelengths to assess the relative number of circulating red blood cells, said Dana Banks, a spokesman for Masimo, according to a report in the journal Scientific American.
For the trial, Ehrenfeld and colleagues recruited 327 patients of orthopedic surgery is scheduled for procedures such as hip replacement (31% of patients), knee (29%), as well as spinal surgery (14%) and randomly assigned each to obtain or standard treatment alone (157 patients) during the operation (ie, where observations and laboratory tests were used to monitor hemoglobin levels), or standard treatment plus SpHb monitoring (150 patients).
They compared the frequency of blood transfusion during the surgery done and the average number of units of blood transfusion in the two groups, and they also compared the frequency of Hb testing laboratory and the agreement between the laboratory and hopes SpHb Hb counts.
They also assessed the complications for each group 30 days after surgery.
The results showed that: There were no significant differences between groups in terms of physical condition, sex, laboratory hemoglobin before they underwent surgery, and duration or type of surgery. Most of the patients, blood transfusion during surgery in a group of standard care, compared with a group of SpHb (4,5% against 0,6%, p = 0.03). The average number of units of blood used in transfusions was significantly higher in the standard of care than group SpHb (0,10 vs. 0,01, p = 0.0001). There was little difference between groups in frequency and average number of laboratory studies, hemoglobin (16.3% vs. 11.8%, and 0.21 vs. 0.24 tests in the case p = n, in both cases). Hb values obtained SpHb and laboratory tests showed good agreement. There were no transfusions in either group within 12 hours after surgery and there was no difference between groups in the 30-day complications of that. Ehrenfeld and colleagues concluded:
"The use of monitoring SpHb has resulted in fewer intraoperative blood transfusion."
SpHb Masimo device is already used in the Brookdale University Hospital and Medical Center in Brooklyn, New York, where, according to Dr. Thomas coal, director of conservation programs of blood, it helps them to "proactively identify and address patients requiring blood transfusion is much earlier, while avoiding unnecessary blood transfusions and other invasive tests. "
Nevertheless, more data is needed before the device more widely available.
Ehrenfeld said the next step will be to make the larger vessels, to see how the device affects rates of transfusion in other patient groups, including those who are exposed to trauma and heart surgery, where more blood is often needed.
"The impact of continuous and noninvasive hemoglobin monitoring for intraoperative blood transfusion." Jesse M. Ehrenfeld, Justin P. Henneman. Presented at the American Society of Anesthesiologists, annual meeting, San Diego, October 18, 2010. Abstract Number: LB05.