Hmm, I had Lidocaine a few weeks before giving birth to my son for a tooth extraction (that could not wait as it was infected), and was told by the dentist that the dose will not harm the baby. Perhaps it is dose-dependent? I would probably just dump the first feeding, and not the second one...I guess it depends on how uncomfortable you are with your baby potentially being exposed to some of the drug, how much of the drug will still be in your system, how much will pass on into the milk, and how inconvenient or wasteful dumping the second pump will be (i.e. if you have low supply or other issues).
Here's one bit of info I found:
"Small amounts of lidocaine are excreted into breast milk (24). A 37-year-old, lactating woman was treated with intravenous lidocaine for acute onset ventricular arrhythmia secondary to chronic mitral valve prolapse. The woman had been nursing her 10-month-old infant up to the time of treatment. She was treated with lidocaine, 75 mg over 1 minute, followed by a continuous infusion of 2 mg/minute (23 g/kg/minute). A second 50-mg dose was given 5 minutes after the first bolus dose. The woman's serum lidocaine level 5 hours after initiation of therapy was 2 g/mL. The drug concentration in a milk sample, obtained 2 hours later when therapy was stopped, was 0.8 g/mL (40% of maternal serum). Although the infant was not allowed to nurse during and immediately following the mother's therapy, the potential for harm of the infant from exposure to lidocaine in breast milk is probably very low. The American Academy of Pediatrics considers lidocaine to be compatible with breast feeding (25)." (
http://drugsafetysite.com/lidocaine/)
