The CBO is required to analyze each bill as it is written, which allows them to drop the full context of a bill's costs. The following two links will provide you with information you need to understand why Obama and Pelosi's claims can only be acts of intentional deception.
The Real Arithmetic of Health Care Reform NYT by Former CBO Director Douglas Holz-Eakins
Letter from CBO Director Douglas Elmendorf on the combined effects
of HR 3590 (Senate HC bill just passed) HR 4872 (the "reconcilation" bill) and HR 3961 (Medicare Physicians Payment Reform Act of 2009) March 19, 2010
Also: The Lie of Fiscal Responsibility Reason March 22, 2010