Hamilton acute pain service safety study: using root cause analysis to reduce the incidence of adverse events.

BACKGROUND: Although intravenous patient-controlled analgesia opioids and epidural analgesia offer improved analgesia for postoperative patients treated on an acute pain service, these modalities also expose patients to some risk of serious morbidity and even mortality. Root cause analysis, a process for identifying the causal factor(s) that underlie an adverse event, has the potential to identify and address system issues and thereby decrease the chance of recurrence of these complications. METHODS: This study was designed to compare the incidence of adverse events on an acute pain service in three hospitals, before and after the introduction of a formal root cause analysis process. The "before" cohort included all patients with pain from February 2002 to July 2007. The "after" cohort included all patients with pain from January 2009 to December 2009. RESULTS: A total of 35,384 patients were tracked over the 7 yr of this study. The after cohort showed significant reductions in the overall event rate (1.47 vs. 2.35% or 1 in 68 vs. 1 in 42, the rate of respiratory depression (0.41 vs. 0.71%), the rate of severe hypotension (0.78 vs. 1.34%), and the rate of patient-controlled analgesia pump programming errors (0.0 vs. 0.08%). Associated with these results, the incidence of severe pain increased from 6.5 to 10.5%. To achieve these results, 26 unique recommendations were made of which 23 being completed, 1 in progress, and 2 not completed. CONCLUSIONS: Formal root cause analysis was associated with an improvement in the safety of patients on a pain service. The process was effective in giving credibility to recommendations, but addressing all the action plans proved difficult with available resources.

Oxidation of the lignan nordihydroguaiaretic acid.

The naturally occurring antioxidant lignan nordihydroguaiaretic acid has been used in traditional medicine to treat a variety of conditions and more recently has been investigated for its anticancer and antimicrobial properties. Nordihydroguaiaretic acid has also been shown to cause kidney toxicity in rats and there is evidence to suggest that chronic nordihydroguaiaretic acid consumption may cause liver toxicity in humans. Nordihydroguaiaretic acid likely undergoes biotransformation to a reactive quinone species, either an ortho-quinone or a para-quinone methide, which is responsible for its toxicity. In an effort to probe the toxicity of nordihydroguaiaretic acid, we oxidized nordihydroguaiaretic acid with both chemical and enzymatic systems and trapped the resultant products with glutathione. The nordihydroguaiaretic acid-glutathione adducts were compared with the products found when nordihydroguaiaretic acid was incubated in rat hepatic microsomes in the presence of glutathione. Glutathione metabolites consistent with ortho-quinone formation were the only oxidation products observed. Control experiments in microsomes however suggested that a majority of the nordihydroguaiaretic acid ortho-quinone glutathione adducts were formed as the result of nordihydroguaiaretic acid autoxidation. We measured the rate of this autoxidation process over a range of pH values and determined that the autoxidation reaction is base-catalyzed. We suggest that caution must be exercised when using nordihydroguaiaretic acid in experiments above pH 7.4 as relatively little of the parent compound may be left in incubations longer than 3 h.