Please see this caution for hospital staff, carers and families:

Ecig Charging and Oxygen - Warning for Hospitals and Carers

Note that ecig use with oxygen has not by itself caused any incident - but recharging an eGo type unit has, due to the fires that these units suffer from while on charge. Because of this, ecigs must not be recharged in any room where oxygen is available.

Do not allow oxygen-using patients to recharge their ecig in the same room and especially not on the bedside table.