Please select the eligibility criteria that correspond to the clinical trial below.
Title: Supplemental Perioperative Oxygen Reduces the Risk of Surgical Wound Infection: A Randomized, Double-blind Trial
Brief Summary: Supplemental perioperative oxygen has been reported to halve or double the risk of surgical wound infection. We tested the hypothesis that supplemental oxygen reduces infection risk following colorectal surgery. Colorectal surgery patients (n=300) were randomly assigned to 30% or 80% FiO2 intraoperatively and 6 hours postoperatively. Wound infections were diagnosed by blinded investigators using Centers for Disease Control criteria. Baseline patient characteristics, anesthetic management, and potential confounding factors were recorded. Wound infection rates were compared with chi-square analysis. Logistic regression identified the contribution of potential confounding factors. Surgical wound infection occurred in 24.4% of patients receiving 30% oxygen, but only 14.9% of those receiving 80% oxygen (P\<0.039). According to logistic regression, the relative risk of infection in patients given supplemental oxygen was 0.46 (P=0.035). Supplemental inspired oxygen reduced wound infection risk by roughly a factor of two. We thus recommend that supplemental oxygen be provided to patients undergoing colorectal surgery.


Options:
A: Inclusion Criteria:

* Age 18 years or older.
* Laparotomy, acute or elective. In case of gynaecological surgery only if malignancy is suspected (defined as risk of ovarian malignancy index \>200 or a specimen with atypical or neoplastic cells).

Exclusion Criteria:

* Other surgery within 30 days (except surgery in local anaesthesia).
* Chemotherapy within 3 months.
* Inability to give informed consent.
* Inability to keep oxygen saturation above 90% without supplemental oxygen (measured preoperatively by pulse oximetry).
B: Inclusion Criteria:

* Colon resection expected to last \>2 and \<6 hours

Exclusion Criteria:

* Bowel obstruction
* Fever
C: Inclusion Criteria:

* Elective colorectal resection,
* Patients having abdominal-peritoneal reconstructions were included, but not those scheduled for minor colon surgery (e.g., polypectomy, isolated colostomy) or laparoscopic surgery.

Exclusion Criteria:

* Exclusion criteria included expected surgery time of less than one hour, fever or existing signs of infection, diabetes mellitus (type I or II), HIV infection, weight loss exceeding 20% in the previous three months, serum albumin concentration \< 30 g/L, and a leukocyte count \<2500 cells/ml.
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: C