Your question is about "Would it be kidnapping if I was injured and someone took me to a hospital without my consent", so I don't understand these other answers which say "it depends on the situation".
The key point is what you mean by "without my consent".
Good Samaritan laws are also relevant, which offer defenses to people who do things that would otherwise be unlawful when they are doing it with good intentions to help someone who they believe is injured or would become injured without their intervention.
The main things to consider are the degree of injury, which is a spectrum ranging from no injury at all to being dead, and whether the injured person is conscious.
Are you so injured that you are unconscious? In most jurisdictions, being unconscious is considered as you consenting to any actions which are done with the intent of giving you medical assistance, which is on a spectrum of saying "hey are you ok?" or shaking you in order to wake you up, all the way up to treatment including major surgery.
So by being unconscious it is usually automatically consent, but if you are awake and are refusing help or treatment, even if you could die if you didn't receive treatment, it would be easy to argue that you were not consenting and that any treatment/assistance etc was unlawful. This situation sometimes happens, and EMTs are often trained to wait until the person goes unconscious to then give them medical assistance/transport etc, but assisting someone before they go unconscious could still be argued as permissible, if the injured person was so distressed that they were unable to give/refuse consent, or at least if the assistor believed that to be the case.
This is why if someone has a major medical problem and is unconscious, hospitals can perform surgery on them without them signing a consent form. By being unconscious, it is considered that they are consenting to any necessary surgery to help them, even including amputation or other negative consequences. Conversely, if someone has a tattoo on their chest which says DO NOT RESUSCITATE (which is common), they will be considered not to consent, and will usually be left alone without life-saving assistance. Resuscitating/performing surgery on someone in this case can be cause for damages to the injured person, because it would have been clear that they did not consent to such assistance.