<prompt> Which of the following produces the least damage to blood elementsDisc oxygenatorMembrane oxygenatorBubble oxygenatorScreen oxygenator  <response>: B i.e. Membrane Oxygenator Membranous pump oxygenators produce least damage to blood elements RBCs, WBCs, plateletsQ and cause least denaturation of proteins. They have improved the efficiency of gas exchange while minimizing the trauma to blood elements. Due to these advantages membrane oxygenators have largely replaced bubble oxygenators. Oxygenators are devices used in cardiopulmonary bypass surgeries. Currently only two types of oxygenators -Membranous bubble oxygenators are in use. Membranous oxygenators imitate the natural lung by interspersing a thin membrane between gas and blood phases. This eliminates gaseous micro emboli formation minimizes blood element trauma. Hematological advantages of membranous oxygenator vs bubble oxygenators are - less trauma to RBC, WBC, platelet less protein denaturation. Due to these advantages membranous oxygenators have largely replaced bubble oxygenators. Disc oxygenators veical screen oxygenators were used in past. 