the investigators will pursue two specific aims: (1) to monitor the extent of heme oxygenase induction (by measuring endogenous CO production) in relationship to the extent of hepatic resection (2) to assess the production of CO in patients following liver resection and correlate these findings to the rate of liver regeneration and liver function.

Inclusion Criteria:

• Patient plans to have partial liver resection for primary liver pathology or metastatic disease
• Patient is able to comprehend and willing to sign the written consent form

Exclusion Criteria:

• Patients < 18 years
• Patients identified as members of a vulnerable population, except women of child bearing potential with negative pregnancy test