Analgesic efficacy of equimolar 50% nitrous oxide/oxygen gas premix (Kalinox®) as compared with a 5% eutectic mixture of lidocaine/prilocaine (EMLA®) in chronic leg ulcer debridement.

Chronic foot and leg ulcers are a common health problem worldwide. A mainstay of chronic ulcer therapy is sharp mechanical wound debridement requiring potent analgesia. In this prospective, controlled, single-centre, crossover design study, patients were assigned to either the administration of topical analgesia with 5% lidocaine/prilocaine cream or the inhalation of an analgesic 50% N2 O/O2 gas premix. Primary outcome parameter was level of pain at maximum wound depth during debridement as measured by a visual analogue scale. Secondary outcomes included level of pain after debridement, overall duration of treatment session, duration and completeness of debridement, and the patient's subjective perception of analgesic quality during debridement. Pain level increased from 0·60/0·94 (first/second debridement; baseline) to 1·76/2·50 (debridement) with 5% lidocaine/prilocaine and from 1·00/1·35 (baseline) to 3·95/3·29 (debridement) with 50% N2 O/O2 gas premix. Patient satisfaction was 90·48%/94·44% (first/second debridement) with topical 5% lidocaine/prilocaine analgesia and 90·48%/76·47% with the inhalation of 50% N2 O/O2 gas premix. Debridement was completed in a significantly higher percentage of 85·71%/88·89% (first/second debridement) with 5% lidocaine/prilocaine than with 50% N2 O/O2 gas premix (42·86%/58·82%) (odds ratio 6·7; P = 0·001). This study provides sound evidence that analgesia with topically administered 5% lidocaine/prilocaine cream is superior to the use of inhaled 50% N2 O/O2 gas premix in chronic leg ulcer debridement.

Perinatal neuroprotection by muscle relaxants against hypoxic-ischemic lesions: is it a possible hypothesis?

The incidence of neurological disabilities ascribable to hypoxia-ischemia in the perinatal period (HIPP) is rising. Glutamate plays a key role in the development of cerebral damage related to HIPP: it triggers the excitotoxic cascade by overactivating N-methyl-D-aspartate receptors (NMDA), implicated as important mediators of both learning and neuronal development. Laudanosine is the metabolite of the neuromuscular blocking drugs, atracurium and cisatracurium, administered as part of obstetric general anesthesia. In elective cesarean section, laudanosine may be found in the fetus with a mean umbilical vein concentration of 26 (range 6-60) ng ml(-1). At nM concentrations, laudanosine can activate alpha4beta2 nACh subtype receptors. Activation of alpha4beta2 nAChRs provided neuroprotection against NMDA excitotoxic cascade in a neonatal model. Taken together, experimental and clinical data widely indicate a potential neuroprotective role for laudanosine against perinatal brain lesions of hypoxic-ischemic origin. The clinical relevance is that administration of the neuromuscular blocking drugs atracurium and cisatracurium, administered as part of general anesthesia for cesarean section, could be potentially therapeutic in obstetric anesthesia. Therefore, we find laudanosine to be an attractive proposal for further studies in the prevention of neurological disabilities ascribable to perinatal injury related to hypoxia and ischemia.