Plasma fibronectin and complement following infusion of colloidal solutions after spinal anaesthesia

A randomized study of 30 patients undergoing uncomplicated surgery under spinal anesthesia was conducted to assess the influence of colloids on the kinetics of plasma fibronectin and complement. Both are opsonins of the reticuloendothelial system; moreover fibronectin is concerned with host resistance against septic complications following trauma and surgery. The patients were assigned to receive either Ringer's lactate (Group 1), gelatin (Group 2) or dextran 40 (Group 3). Blood samples were withdrawn before colloids or Ringer's infusion and during the 4 postoperative days. There was a reduction in plasma fibronectin throughout the study in groups 1 and 3, but an increase in group 2 by 24 h. The adhesion of plasma fibronectin to gelatin was maximal 1 h after infusion (44%) and remained significant up to day 2 in group 2. There was no relationship in groups 1 and 3. C3 and C4 components of complement exhibited a low value in the early post-operative period, due to hemodilution. This study shows an in vivo fibronectin-gelatin interaction, and suggests that gelatin infusion inhibits the increased shift of plasma fibronectin at the site of tissue injury after surgery.

Oxygen uptake after major abdominal surgery: effect of clonidine

To examine the effect of an alpha-2 agonist, clonidine, on oxygen uptake and on the incidence of postoperative shivering, 28 patients presenting for major abdominal surgery were randomly assigned in a double-blind manner to one of two groups. Intraoperatively, 14 patients received 5 micrograms.kg-1 clonidine infused over 3 h (clonidine group), and 14 patients received placebo (placebo group). Oxygen uptake was measured continuously over the first 3 postoperative hours with a mass spectrometer system. Circulatory variables, esophageal temperature, and skin temperature were measured over the first 6 postoperative hours. Heart rate, mean arterial pressure, rate pressure product, and norepinephrine concentration were decreased in the clonidine group (P less than 2 x 10(-4)). There were no differences among groups in the incidence of shivering and in the rate of increase of esophageal temperature. By contrast, oxygen uptake was lower in the clonidine group (P = 4 x 10(-4)). This contrasting pattern may be secondary to a reduction in the intensity of mean muscular tremor in the clonidine group.

[Colloid substitutes and hematocrit measurement by micromethods]

A study was carried out to determine whether centrifugation and resistivity were reliable methods for measuring haematocrit of blood diluted with dextran or gelatin. The values obtained with the minicentrifuge Compur M 1100 (Bayer) (group 2) and with the Stat-Crit (Fumouze) (group 3) were compared with those obtained with the reference method (Coulter counter Model S + 2, Coultronics) (group 1). The study included 10 healthy subjects, aged 21 to 43 years. In each, sodium, potassium, chloride and protein concentrations were determined. Two further 10 ml blood samples were taken to be diluted with increasing amounts of either a fluid modified gelatin (Plasmion) or a dextran 40 (Piasmacair). The dilutions carried out were 0, 10, 20, 30, 40 and 50%. For each one, the haematocrit was measured using all three methods. The values obtained with undiluted blood were similar with the three methods. However, when blood was diluted with a dextran, haematocrit values were underestimated, whatever method was used, but by no more than 5% (difference not statistically significant). The result was the same with the centrifugation method for blood diluted with gelatin. On the other hand, values obtained with the resistivity technique for these samples were underestimated up to 15.5% (50% dilution; p less than 0.05). This was due to the negative electric charge of the gelatin, which lowered the haematocrit value in proportion to the concentration of gelatin. Although the technique is easier than centrifugation, measuring haematocrit with a resistivity method should be avoided in patients receiving a fluid modified gelatin.