Martin Gleim

The stability of mixtures of morphine hydrochloride, bupivacaine hydrochloride, and clonidine hydrochloride in portable pump reservoirs for the management of chronic pain syndromes

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.

Diagnostik und Therapie des sympathisch unterhaltenen Schmerzes

ZusammenfassungDer „sympathisch unterhaltene Schmerz” (SMP) ist ein Symptom mit variabler Ausprägung und Häufigkeit mit verschiedenen Schmerzerkrankungen (u.a. CRPS, Zoster- und posttraumatische Neuralgie), das in einen vom Sympathikus unabhängigen Schmerz (SIP) übergehen kann. Ein SMP kann nicht durch klinische Merkmale, sondern nur durch die Analgesie nach einer Sympathikusblockade verifiziert werden. Die Interventionsverfahren (Grenzstrangblockade, IVRS, GLOA) unterscheiden sich hinsichtlich ihrer diagnostischen Sensitivität und Spezifität und der therapeutischen Effektivität. Das Risiko einer falsch-positiven Diagnose eines SMP wird durch optimale Technik und differenzierte Dokumentation, das einer Fehldiagnose eines SIP nur durch aufwendiges Monitoring (Messung sympathischer Reflexe) verringert. Es werden ein Modell für den Pathomechanismus, das die klinische Symptomatik in bislang experimentell begründete Hypothesen integrieren soll, sowie Algorithmen für die Diagnostik und die Therapie des SMP diskutiert.AbstractThe 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.

Lumbar neurolytic sympathetic blockades provide immediate and long-lasting improvement of painless walking distance and muscle metabolism in patients with severe peripheral vascular disease

Thirty patients with angiographically proven peripheral vascular disease (PVD) and intermittent claudication were treated with percutaneous lumbar neurolytic sympathetic blockade (NSB) using 1.5 mL ethanol 95%. Claudication had been progressive in all patients during conservative treatment. Median (range) painless walking distance increased from 95 (10-200) meters (m) before to 355 (25-1003) m immediately after NSB. Further improvement was seen during the 1-year follow-up, with two exceptions: one patient lost a leg after acute arterial embolism and another patient deteriorated after 6 months. In the latter case, a second NSB improved the walking distance again. One case of transient mild neuralgia of the L3 dermatome occurred. 31P-magnetic resonance investigations of the calf muscles before, during, and after a treadmill exercise were performed in seven patients: 1 week after NSB, the postexercise recovery of phosphocreatine was accelerated in all patients compared to the pre-NSB values. The accelerated recovery suggests an improved post-ischemic metabolic situation after chemical sympathectomy.