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In conclusion, both PLMA and LTS proved to be suitable for routine surgical procedures and proved to be superior to the OTC which cannot be recommended for routine use.

The physical and chemical stability of a combination of drugs commonly administered into the epidural or intrathecal space for the treatment of chronic pain was investigated. The concentrations of bupivacaine hydrochloride, morphine hydrochloride, and clonidine hydrochloride were measured using high performance liquid chromatography. The solutions were stored in reservoir bags for up to 90 days. No macroscopic or microbiological signs of precipitation, change in color, or contamination were observed, and pH remained stable. None of the three drugs declined in concentration during the observation period. A small increase in concentration of all three drugs did occur over time, most probably due to evaporation processes. In conclusion, no problems in physical or chemical stability are to be expected when combining morphine, bupivacaine, and/or clonidine for long-term epidural or intrathecal administration. In the case of clinically apparent loss of analgesic efficacy, other mechanisms should be considered.

SummaryWe have used the up-and-down allocation technique to assess the relative analgesic potencies of epidural ropivacaine alone and ropivacaine combined with sufentanil 0.75 mg.ml 21 in 42 women requesting epidural analgesia in the first stage of labour. Parturients were randomly allocated to one of the two epidural solutions in a double-blind manner. The concentration of local anaesthetic was determined by the response of the previous parturient: an effective concentration (pain # 10 mm on a 10-cm visual analogue pain score within 30 min) resulted in a 0.01% decrease in the concentration of ropivacaine for the next parturient, an ineffective concentration resulted in a 0.01% increase. Minimum local analgesic concentration of ropivacaine alone was 0.13% (95% CI 0.12±0.13%) compared with 0.09% (95% CI 0.08±0.1%) for ropivacaine with sufentanil (p , 0.00001).

The term "sympathetically maintained pain" (SMP) describes a symptom that might accompany a variety of diseases (CRPS, (post-) herpetic and post-injury neuralgia), which might transform into sympathetically independent pain (SIP) after some time. Patients with SMP present a bunch of disorders of the autonomic and sensory system, but the only reliable way to diagnose a pain as SMP is a positive response to an intervention at the sympathetic nervous system. Three ways of influencing the sympathetic system are commonly used: (a) local anesthetic sympathetic blockade (SB), (b) intravenous regional sympathectomy (IVRS) and (c) ganglionic local opioid application (GLOA). A review of current literature shows that SB has certain advantages in diagnostic sensitivity, whereas GLOA might be slightly superior in therapy of some diseases with longstanding pain history. Obviously, the therapeutic benefit of all interventions is complete independent of the accompanying autonomic disorder and of a blockade of efferent fibers. A new heuristic model of the SMP mechanism is presented, including both experimental and clinical data. For reducing the risks of false positive or negative diagnosis of SMP and SIP, a diagnostic algorithm is proposed. This includes optimizing the technique, changes of interventional measures, and adequate monitoring both of analgesia and as well of the extend of efferent sympathetic blockade (e.g. measurement of sympathetic reflexes). The treatment recommendations in patients with SMP vary in dependence of the kind of disease. In SMP, invasive measures play an important, but only limited role within the comprehensive treatment concept. As an example a three-stage, symptom-adapted treatment algorithm is demonstrated for CRPS, including also drug therapy, psychologic and physiotherapeutic approaches.