North American survey of the management of dural puncture occurring during labour epidural analgesia.

PURPOSE: To document the range and the most common strategies for the management of the parturient with inadvertent dural puncture (DP) during labour epidural analgesia. METHODS: A confidential survey form was mailed to 46 academic units in Canada and USA. The responses were compiled into Canadian, US and joint North American databases. RESULTS: Thirty-six centres (78%) responded, representing 137,250 annual deliveries. The reported incidence of DP was 0.04-6%. The most common initial response to DP was resiting the catheter at another level. Most centres made little change in routine practice regarding epidural top-ups and infusion rates after DP. Unrestricted mobilisation was advocated by 86% of centres following delivery; enhanced oral hydration was encouraged by 61%. Prophylactic epidural blood patch (PEBP) was recommended by 37% of centres, with twice as many US as Canadian centres doing so. In the presence of PDPH, EBP was offered most commonly at or within 24 hr of diagnosis. Complications were common after EBP: 86% of centres reported patch failures; 44% reported persistent headache after > or = 2 EBP. Despite this, centres remained optimistic about EBP success, quoting cure rates > 90% in 58% of centres. CONCLUSION: There is little difference between the practices reported by Canadian or US centres. The expressed optimism regarding the efficacy of EBP is not supported by the evidence available and may be unwarranted. More research is needed to define the issue better.

The effects of the phosphorothioate insecticide fenitrothion on mammalian cytochrome P450-dependent metabolism of estradiol.

Phosphorothioate insecticides, such as fenitrothion, are suicide substrates of cytochromes P450 (P450). These compounds undergo oxidative desulfuration by P450 resulting in the release and subsequent binding of atomic sulfur to the enzyme. Consequently, the P450-dependent metabolism of certain endogenous substrates could be inhibited by exposure to these insecticides. Formation of 2-hydroxyestradiol (2-OHE2), 4-hydroxyestradiol (4-OHE2), 16 alpha-hydroxyestrone (16 alpha-OHE1), and estriol in mammals occurs by P450-dependent hydroxylation of estradiol at various positions on the steroid nucleus. In the present study, pretreatment of male Swiss Webster mice with increasing doses of fenitrothion resulted in dose-dependent biphasic decreases in 2-OHE2 and 4-OHE2 production in mouse hepatic microsomes compared to control, with substantial decreases even at a dosage as low as 7 mg/kg. Fenitrothion pretreatment also resulted in dose-dependent biphasic increases in 16 alpha-OHE1 and estriol production, along with substantial increases in estrone formation, probably as a result of shunting from the inhibition of 2- and 4-hydroxylation. These data suggest that exposure to fenitrothion might alter estradiol metabolism by inhibition of certain P450 isozymes.