Please select the eligibility criteria that correspond to the clinical trial below.
Title: Large, Randomised, Parallel-group, Controlled Trial, With Patients Randomly Allocated to Either N2O-containing (70% N2O in Oxygen [FiO2 0.3]) or N2O-free (70% Nitrogen in Oxygen [FiO2 0.3]).
Brief Summary: To investigate the safety of nitrous oxide (N2O) anaesthesia in patients with risk factors for coronary artery disease undergoing major surgery.


Options:
A: Inclusion Criteria:

* mentally competent patients undergoing cesarean section under spinal or epidural anesthesia

Exclusion Criteria:

* fever/chorioamnionitis; GBS positive on antibiotics; immunocompromised / HIV patients; on antibiotics for any reason; general anesthesia; age less than 18 years custody patients stat cesarean section
B: Inclusion Criteria:

* Adults ≥ 18 years of age.
* Chest pain for \< 12 hours
* ST-elevation Myocardial Infarction including either: 1) Persistent ST-segment elevation of ≥1mm in two contiguous limb leads; 2) ST-segment elevation of ≥ 2mm in two contiguous chest leads, or; 3) New left bundle branch block (LBBB) pattern.
* Able to be transported to a participating hospital

Exclusion Criteria:

* Hypoxia with oxygen saturation measured on pulse oximeter \< 94% with the patient breathing air
* Bronchospasm requiring nebulised salbutamol therapy using oxygen
* Altered conscious state
C: Inclusion Criteria:

1. Males and females, age 18 years and over
2. Planned general anaesthesia for surgery that includes a skin incision and expected to exceed two hours, and the patient is expected to be in hospital for at least three days

Exclusion Criteria:

1. Endoscopic or radiological procedures
2. Cardiac surgery
3. Marked impairment of gas-exchange (requiring Fi02\> 0.3)
4. Thoracic surgery requiring one-lung ventilation (requiring Fi02\> 0.3)
5. Specific circumstances where N2O is contraindicated (eg. volvulus, pulmonary hypertension, raised intracranial pressure)
6. Lack of provision of N2O.
D: Inclusion Criteria

1. Adult males and females age ≥ 45 years, undergoing noncardiac surgery and general anaesthesia expected to exceed two hours.
2. At increased risk of cardiac events, defined as any of

   1. history of coronary artery disease as defined by a history of any one of the following: i. angina ii. MI iii. segmental wall motion abnormality on echocardiography or a fixed defect on radionuclide imaging iv. a positive exercise stress test for cardiac ischaemia v. a positive radionuclide exercise, echocardiographic exercise, or pharmacological cardiovascular stress test for cardiac ischaemia vi. coronary revascularization (CABG or PTCA) vii. angiographic evidence of atherosclerotic stenosis \> 50% of the diameter of any coronary artery viii. ECG with pathological Q waves in two contiguous leads
   2. heart failure
   3. cerebrovascular disease thought due to atherothrombotic disease
   4. aortic or peripheral vascular disease
   5. or three or more of the following risk factors:

      * age ≥70 years
      * any history of congestive heart failure
      * diabetes and currently on an oral hypoglycaemic agent or insulin therapy
      * current treatment for hypertension
      * preoperative serum creatinine \>175 micro mol/L (\> 2.0 mg/dl)
      * current or previous high cholesterol ≥6.2 mmol/L (\> 240 mg/dl)
      * history of a transient ischemic attack (TIA) (i.e. a transient focal neurological deficit that lasted less than 24 hours and thought to be vascular in origin)
      * emergency/urgent surgery (i.e. surgery which must be undertaken within 24 hours of acute presentation to hospital)
      * high-risk type of surgery (i.e. intrathoracic or intraperitoneal)

Exclusion Criteria

1. having cardiac surgery
2. marked impairment of gas-exchange expected to require Fi02\> 0.5 intraoperatively
3. specific circumstances where N2O is contraindicated (eg. volvulus, pulmonary hypertension, raised intracranial pressure) or the anaesthetist plans to use supplemental oxygen (eg. colorectal surgery)
4. N2O unavailable for use.

Answer: D