Can chronic prescribed use of lithium carbonate in an 85 year old elderly patient being treated for bi-polar disorder/depression for past five years coupled with recent prescription of coumadin (within the past 2 months) cause lithium toxicity manifested by delirium symptoms in the elderly patient, as well as very low heart rate? Delirium in this instance manifested as inability to communicate & sudden onset of just muttering and moaning within a week's timeframe, after previously being able to effectively communicate with caretakers by talking.