The short answer is no; you have to have the patient's signature on the NPP to show that you have been given permission to share their PHI with their insurance and electronic clearinghouses - you could be setting yourself up for trouble if not. You can make a reasonable attempt to get it after the fact, and document your efforts, though...see this article from HHS about it:
"•Covered Direct Treatment Providers must also: ◦Provide the notice to the individual no later than the date of first service delivery (after the April 14, 2003 compliance date of the Privacy Rule) and, except in an emergency treatment situation, make a good faith effort to obtain the individual's written acknowledgment of receipt of the notice. If an acknowledgment cannot be obtained, the provider must document his or her efforts to obtain the acknowledgment and the reason why it was not obtained.
◦When first service delivery to an individual is provided over the Internet, through e-mail, or otherwise electronically, the provider must send an electronic notice automatically and contemporaneously in response to the individual's first request for service. The provider must make a good faith effort to obtain a return receipt or other transmission from the individual in response to receiving the notice.
◦In an emergency treatment situation, provide the notice as soon as it is reasonably practicable to do so after the emergency situation has ended. In these situations, providers are not required to make a good faith effort to obtain a written acknowledgment from individuals.
◦Make the latest notice (i.e., the one that reflects any changes in privacy policies) available at the provider's office or facility for individuals to request to take with them, and post it in a clear and prominent location at the facility.
•A covered entity may e-mail the notice to an individual if the individual agrees to receive an electronic notice. See 45 CFR 164.520(c) for the specific requirements for providing the notice."
http://www.hhs.gov/ocr/privacy/hipaa/understanding/coveredentities/notice.html
