An advance medical directive gives instructions on the kind of medical care you would like to receive should you become unable to express your wishes yourself, and it often designates someone to make medical decisions for you. This is an extremely important document – but it won’t be of much value in an emergency if it’s tucked away in a safe deposit box or in a file cabinet where no one can easily find it.

It’s a good idea to carry a card in your wallet or purse saying that you have a directive, and how medical personnel can access it.

For instance, if you routinely carry a cell phone or tablet with you, you could upload your directive as a file on your device.

If you don’t typically carry such a device, but you have a child who does, you could ask the child to upload it to his or her phone or tablet. Your card could instruct medical personnel to contact your child. Your child would then be able to e-mail the directive to the doctors – even if the child is thousands of miles away at the time.

There are a growing number of software programs, apps and cloud-based options that offer to store health care and legal documents and make them available in an emergency. Also, about a dozen states have established online registries for advance directives.

But the most important step is to have an advance directive in the first place. Most Americans still don’t – and that can create agonizing quandaries for loved ones in a crisis.