Double blind double dummy of Intravenous Acetaminophen and oral acetaminophen placebo versus IV placebo versus oral acetaminophen in patients following cardiac surgery. The primary endpoint is development of Delirium during the post-operative stay.

The study is randomized, double-blinded, and multicentre. Enrollment includes patients 18 years or older who are going for aortocoronary bypass surgery, single valve, or bypass and single valve. The intervention is blinded IV acetaminophen and blinded oral active or placebo acetaminophen . The study will start with a pilot trial of 120 patients at 4 centers- 30 at each site, 15 per group. The pilot is a vanguard. If the pilot shows appropriate compliance with the protocol, reliable blinding and appropriate enrolment, the results will not be unblinded but rolled into the full study. Stratification will be by site and age < 60 or >= 60.

Inclusion Criteria:

• subjects > 18 years of age undergoing elective aortocoronary bypass, single valve replacement or single valve and aortocoronary bypass surgery

Exclusion Criteria:

• • Refusal by surgeon for inclusion of the patient

  • Requested late extubation by anesthesia or surgeon
  • Intra-aortic balloon pump
  • Sensitivity to acetaminophen
  • Pre-operative cognitive dysfunction
  • Psychiatric history with active treatment
  • Parkinson's disease
  • Alzheimer's disease
  • Medication for cognitive decline
  • History of recent seizures
  • Recent history of alcohol misuse
  • Creatinine clearance less than 30 ml/min

blinded medication with codes kept in the pharmacy