A novel autotransfusion device saving erythrocytes and platelets used in a 72 h survival swine model of surgically induced controlled blood loss.

BACKGROUND: The purpose of this study was to develop a swine model of surgically induced blood loss to evaluate the performances of a new autotransfusion system allowing red blood cells and platelets preservation while collecting, washing and concentrating hemorrhagic blood intraoperatively. METHODS: Two types of surgically induced blood loss were used in 12 minipigs to assess system performance and potential animal complications following autotransfusion: a cardiac model (cardiopulmonary bypass) and a visceral model (induced splenic bleeding). Animal clinical and hematological parameters were evaluated at different time-points from before bleeding to the end of a 72-hour post-transfusion period and followed by a post-mortem examination. System performances were evaluated by qualitative and quantitative parameters. RESULTS: All animals that received the autotransfusion survived. Minimal variations were seen on the red blood cell count, hemoglobin, hematocrit at the different sampling times. Coagulation tests failed to show any hypo or hypercoagulable state. Gross and histologic examination didn't reveal any thrombotic lesions. Performance parameters exceeded set objectives in both models: heparin clearance (≥ 90%), final heparin concentration (≤ 0.5 IU/mL), free hemoglobin washout (≥ 90%) and hematocrit (between 45% and 65%). The device treatment rate of diluted blood was over 80 mL/min. CONCLUSIONS: In the present study, both animal models succeeded in reproducing clinical conditions of perioperative cardiac and non-cardiac blood loss. Sufficient blood was collected to allow evaluation of autotransfusion effects on animals and to demonstrate the system performance by evaluating its capacity to collect, wash and concentrate red blood cells and platelets. Reinfusion of the treated blood, containing not only concentrated red blood cells but also platelets, did not lead to any postoperative adverse nor thrombogenic events. Clinical and comparative studies need to be conducted to confirm the clinical benefit of platelet reinfusion.

Predictive risk factors for pain during extracorporeal shockwave lithotripsy.

PURPOSE: Extracorporeal shockwave lithotripsy (SWL) is a noninvasive but painful procedure. The aim of this study was to identify predictive risk factors for pain during SWL. PATIENTS AND METHODS: Two hundred twenty-two SWL treatments with the Lithostar lithotripter (Siemens) were included in a monocentric study. Patient and stone characteristics were prospectively collected in a database, and a standardized pain control protocol was administered 1 hour before treatment: paracetamol, nefopam, ketoprofen, and alprazolam. Subjective pain level was assessed with visual analog scale (VAS, 0-10). If VAS was >or=3, tramadol was added. If VAS was still >or=3, shockwave intensity was decreased or treatment was interrupted. The efficacy on stone fragmentation was evaluated 1 month after treatment. The need for adjuvant analgesia was compared with patient and stone characteristics to find out predictive risk factors for pain. RESULTS: The average subjective pain was 3.1. The need for supplementary analgesia was more frequent in women (p = 0.035), younger patients (p < 0.001), anxious and depressed patients (p = 0.018), in patients with previous SWL (p = 0.0185), in patients with a rib projected stone (p < 0.001), in patients with renal stones (p = 0.0535), and finally in patients with homogeneous stones (p = 0.02). Multivariate analysis revealed two independent risk factors for pain: young age (odds ratio = 5; p < 0.001) and rib projected stone (odds ratio = 5.23; p < 0.001). Stone fragmentation was worse in patients with an adjuvant analgesia requirement (p = 0.0311). CONCLUSION: Predictive risk factors for pain during SWL treatments were found: young age, rib projected stones, anxious and depressed patients, previous SWL treatment, and homogeneous stones. A higher analgesic requirement is necessary for these preselected patients to perform SWL and optimize its efficacy.