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A randomized study was carried out on 160 patients aged 30–60 years with the aim of finding a method of preventing postdural puncture headache (PDPH). In Taylor's lumbosacral approach to the subarachnoid space, two different needle sizes were used (21-gauge versus 25-gauge) for injecting the anaesthetic solution. Our results show an overall incidence of PDPH in nearly 8% of patients, with no significant difference related to the size of the needle employed. Patients with PDPH showed mild symptoms which disappeared in a short time and none needed epidural blood patching. The possibility of using larger needles, facilitating the execution of the block without increasing PDPH incidence, renders this technique particularly attractive in patients where the midline approach is not feasible, or when pencil-point needles are not available.

This study compares the areas of analgesia obtained with the lateral and posterior approaches to the interscalene space after injection of equal volumes of anaesthetic solution (40 ml of a mixture of 0.5% bupivacaine with adrenaline 1:200,000 and 2% lignocaine in equal parts). There was a significant difference in the distribution of the areas of analgesia between the two approaches. With the posterior approach, the region supplied by the radial, medial and ulnar nerves and the post-axial border of the upper limb were more frequently involved, whilst with the lateral approach the area of analgesia was usually confined to the regions supplied by the most caudal roots of the cervical plexus and the upper trunk of the brachial plexus (pre-axial border of the upper limb). On these grounds it appears that two different types of interscalene block are possible.

Erythrocyte deformability was demonstrated to be influenced by platelet activation. Deformability of erythrocytes suspended in autologous platelet poor plasma (PPP), obtained from platelet rich plasma (PRP), was significantly reduced when PRP had previously been incubated with a platelet activating substance (arachidonic acid, adrenaline or ADP). The possibility of a direct influence of the activating substance on erythrocyte deformability was examined and malondialdehyde formation was determined as an indicator of platelet activation. Erythrocyte deformability was not impaired when endoperoxide formation in platelets was blocked by an inhibitor of cyclooxigenase (acetylsalicylic acid). Plasma viscosity was not influenced by platelet activation as demonstrated by filtration and viscosimetry. Recent studies showed that prostacyclin (PGI2) increases erythrocyte deformability (1). The antagonistic action between prostacyclin released by vessel walls and products of platelet metabolism being well known, we discuss possible mechanisms of this effect and pathophysiological relevance of our results.