Effect of Low Tidal Volume Ventilation in Improving Oxygenation and Thus Reducing Acute Lung Injury in the Cardiac Surgical Patient

Effect of Low Tidal Volume Ventilation in Improving Oxygenation and Thus Reducing Acute Lung Injury in the Cardiac Surgical Patient

We propose that as low tidal volume ventilation has proven to be beneficial in patients with established ARDS it may have a role in preventing the onset of acute lung injury in the cardiac surgical population. Institution of low tidal volume ventilation in the operating room may reduce the release of the cytokines and interleukins that have been known to contribute to the development of acute lung injury. In this study, we propose that the institution of low tidal volume ventilation in the operating room will reduce the incidence of acute lung injury. Measurement of PaO2 to FiO2 ratio twenty four and forty eight hours post operatively will help determine if there is a difference in oxygenation between the two groups. Chest X-ray findings, time to extubation and length of ICU stay will also determine if there is a role for low tidal volume ventilation in the operating room. We will also attempt to establish a causative mechanism by measuring plasma levels of cytokines known to be associated with the development of ARDS.

Methods- A single center randomized controlled trial was undertaken in 149 patients comparing ventilation with 6 ml/kg TV to ventilation with 10 ml/kg TV in patients undergoing elective cardiac surgery. Study ventilator settings were applied immediately after induction of anesthesia and continued throughout surgery and the subsequent Intensive Care Unit stay. The primary endpoint of the study was time to extubation. Secondary endpoints included the proportion of patients extubated at 6 hours, indices of lung mechanics and gas exchange as well as patient clinical outcomes.

Inclusion Criteria:

• Patients coming in for cardiac surgical procedures will be recruited into the study.
• Both men and women will be recruited into the study.
• All patients over the age of 18 will be recruited into the study.
• Discussion between the surgeon and the primary investigator will happen prior to approaching the patient to obtain informed consent.

Exclusion Criteria:

• Patients with preexisting respiratory failure and active infection will be excluded from the study.
• Patients undergoing one lung ventilation during surgery will be excluded from the study.
• Patients undergoing emergency cardiac surgery will be excluded from the study.