Lack or eligible patients.

This study is designed to provide preliminary data to determine if concentrations of piperacillin/tazobactam change in patients with severe respiratory failure receiving extracorporeal membrane oxygenation (ECMO). The investigators hypothesize that patients will have significant changes in concentration measurements, specifically an increased clearance rate and increased volume of distribution, during ECMO as compared to critically ill patients.

In a healthy patient, the lungs provide oxygen to the blood and remove carbon dioxide. However, in patients with severe lung failure, blood may not adequately be delivered to the lungs, or the lungs may not adequately supply blood with oxygen. In this case, patients may require assistance from a machine to help provide this oxygen. Extracorporeal membrane oxygenation (ECMO) is a device that acts as an artificial lung, allowing the patient to recover from their illness. Patients receiving support from ECMO are often put in a medically induced coma while their lungs heal. Certain drugs may stick to the internal surfaces of the machine; therefore leading to decreased concentrations. Patients receiving ECMO often require antimicrobials to treat severe infections. However, little data exist concerning the likely changes in drug concentrations from drug circuit interactions in adult patients receiving ECMO.

Inclusion Criteria:

• Patients 18 years of age or older
• Initiated on VV ECMO for acute respiratory distress syndrome
• Receiving piperacillin/tazobactam

Exclusion Criteria:

• Pregnancy
• Massive blood transfusion (10 units or more of of PRBC) within a 24-hour period
• Prisoners

All adult patients receiving VV ECMO for acute respiratory distress syndrome will be assessed for inclusion into the study.