An apparatus for minimizing the risk of air embolism includes an instrument delivery member 2 having a gas outlet 38 for delivering gas into a patient's thoracic cavity. The gas is directed across an opening 48 in the instrument delivery member 2 to help retain the gas in the patient's thoracic cavity. The gas is preferably carbon dioxide which is more soluble in blood than air which will thereby decrease the likelihood of the patient receiving an embolism due to trapped air in the patient's heart and great vessels after surgery.