Hope it all goes very smoothly.
I have only seen one block too high and it was a woman who was birthing vaginally and had an epidural. It went up to the lungs and we had to call the anethetist whom had to stay for the duration of the block with the resus trolley ready to go. She had alot of respiratory depression but wasn't intubated. It took hours for the block to wear off where the risk was gone for a respiratory arrest.
I have not seen a problem with a spinal in theatre only the one woman. When it happens (only seen it once in 6years) its pretty scary.