Molecular weight of hydroxyethyl starch molecules influences coagulation profile measured by thrombelastography.

BACKGROUND: The consensus about the ideal intravenous fluid in trauma patients remains open. However, hypertonic saline and hydroxyethyl starch (HES) seems to have advantages in terms of immuno-modulatory and haemodynamic effects. Nevertheless clotting abnormalities are frequently reported in association with the use of HES. We investigated the influence of light, medium and heavy molecular weight (MW) hydroxyethyl starch (HES) on coagulation in 29 healthy subjects. METHODS: Ringer's lactate (RL) served as a control solution. Thrombelastography using Haemoscope's Thrombelastograph (TEG) hemostasis system was used to assess the effect of HES polymers and RL. TEG analysis was performed using recalcified native whole blood both with and without the addition of platelet activating factor IV (PAF IV) before and immediately after infusion of one of the solutions. RESULTS: Infusion of RL or one of the three HES solutions exerts an anticoagulant effect as demonstrated by a increase in clot formation time (R) and a decrease in maximum amplitude (MA), and the angle. The addition of PAF IV reversed these changes. CONCLUSIONS: This data indicate clear evidence of platelet activity per se or platelet interaction with the plasmatic coagulation system.

Ultrasonographic guidance for sciatic and femoral nerve blocks in children.

BACKGROUND: Recent studies have shown that ultrasound guidance for paediatric regional anaesthesia can improve the quality of upper extremity and neuraxial blocks. We therefore investigated whether ultrasound guidance for sciatic and femoral nerve blocks prolongs sensory blockade in comparison with nerve stimulator guidance in children. METHODS: Forty-six children scheduled for surgery of one lower extremity were randomized to receive a sciatic and femoral nerve block under either ultrasound or nerve stimulator guidance. After induction of general anaesthesia, the blocks were performed using an ultrasound-guided multiple injection technique until the nerves were surrounded by levobupivacaine, or by nerve stimulator guidance using a predefined dose of 0.3 ml kg(-1) of levobupivacaine. An increase in heart rate of more than 15% of baseline during surgery defined a failed block. The duration of the block was determined from the injection of local anaesthetic to the time when the patient received the first postoperative analgesic. RESULTS: Two blocks in the nerve stimulator group failed. There were no failures in the ultrasound group. The duration of analgesia was longer in the ultrasound group mean (sd) 508 (178) vs 335 (169) min (P < 0.05). The volume of local anaesthetic in sciatic and femoral nerve blocks was reduced with ultrasound compared with nerve stimulator guidance [0.2 (0.06) vs 0.3 ml kg(-1) (P < 0.001) and 0.15 (0.04) vs 0.3 ml kg(-1) (P < 0.001), respectively]. CONCLUSIONS: Ultrasound guidance for sciatic and femoral nerve blocks in children increased the duration of sensory blockade in comparison with nerve stimulator guidance. Prolonged sensory blockade was achieved with smaller volumes of local anaesthetic when using ultrasound guidance.

The effect of different isolation techniques on human osteoblast-like cell growth.

Surgical treatment of post-traumatic or neoplastic bone defects often represents a problem in orthopaedic routine. Autologous tissue always stands for the first choice material. The recent therapeutic approaches for tissue repair of bone defects attempt to mimic the natural process of bone repair by delivering a source of cells capable of differentiating into osteoblasts. In this study two different types of human osteoblast cell harvesting were compared in primary cell culture to evaluate the best way to obtain cells for clinical use. Numerous articles describe the characteristics of each one of these systems, but there is no report comparing the influence of these different isolation techniques on cell growth. Cultures from 22 bone specimens obtained from donors were established in two different ways and their proliferation was compared. An enzymatic procedure to extract human osteoblasts (hOBcol) was used in one group; spontaneous cells outgrowth, human osteoblasts (hOBsog) was expected in the other group. Cells of both groups were characterised as osteoblasts by immunohistochemical staining with Bone Morphogenetic Protein-2,4 (BMP-2,4), expression of collagen type I as well as the amount of alkaline phosphatase activity (ALP) detected in the cell cultures. We found that the time needed in primary cultures till confluence was dependent on the age of the donors as well as on the method of cell harvesting. Cells from under 65-year old donors were growing significantly faster by the hOBcol method as compared to hOBsog 20.57 +/- 2.99 days vs. 30.00 +/- 4.36. Cells harvested from donors older than 65 years of age needed 23.88 +/- 2.95 in the hOBcol compared to 34.25 +/- 4.27 days in the other group. In the experimental cultures, after one passage with trypsin/EDTA, there was a significant difference between the two groups. There was an improved cell growth in the hOBsog group found on days 8, 9 and 10 of cultivation. Immunohistochemical staining as well as ALP activity were similar in both groups. In conclusion this study evaluated an important step for a tissue engineering approach to the repair of bone defects, which may have clinical applications in post-traumatic orthopaedic surgery.