Impact of High Frequency Ventilation During Coronary Anastomosis in Off Pump Coronary Artery Bypass.

Ventilatory protocol: Patients will be randomized to either the apnea group or the HFV group. In the HFV group the patients will be ventilated using a tidal volume of 1.5 ml per kg and a respiratory rate of 100 per minute for as long as the surgeon needs to perform the distal anastomosis of the coronaries.The same surgeon will perform all surgeries. In the Control group, ventilation will be stopped for the duration of the anastomosis as it's done currently. At all other times during the surgery, the ventilatory parameters will be adjusted to maintain a PaCO2 between 40 and 45 mmHg.

The anesthesia protocol for the off pump coronary artery bypass will be as follows: premedication will be left at the discretion of the anesthesiologist. In the operating room, the patient will be instrumented with a radial arterial line before induction. Induction will consist of a bolus of 1.0 mcg per Kg of Sufentanil. Anesthesia will be maintained with 1mcg per Kg per hour of Sufentanil. One per cent Isoflurane will be used as hemodynamic parameters allow. Rocuronium 0.7 mg per Kg will be used to facilitate endotracheal intubation. Following endotracheal intubation the patients will monitored with a pulmonary artery catheter and a femoral arterial line. A perfusionist will be on standby at all times for possible conversion to extracorporeal circulation.

Measures to effect:

Routine baseline laboratory investigations will be performed at admission of the patient to the ward.

Hemodynamic parameters: