IN-SITU CONTROL OF CARDIOTOMY SUCTION REDUCES BLOOD TRAUMA

Cardiotomy suction is known for its deleterious effects on formed and unformed blood elements. The authors investigated an ''intelligent'' r emote controlled automatic suction system. A suction cannula with an o ptic sensor at its tip was connected to a special closed cardiotomy re servoir. Contact with blood immediately generated a reservoir vacuum f rom 0 to -100 mmHg, permitting aspiration until the blood was no longe r detected (automatic shut off). flood trauma was evaluated in a bovin e model, comparing the automatic suction system vs standard continuous aspiration (control) adjusted to -100 mmHg. After full systemic hepar inization, five calves (weight, 62.5 +/- 4.4 kg) for the automatic suc tion system group, and four (weight, 62.8 +/- 5.1 kg) for the control group, were equipped with a jugular cannula connected via a roller pum p to the cardiotomy reservoir. Through a small thoracotomy, a standard ized hole was created in the right atrium, allowing for a blood loss o f approximate to 400 ml/min. The suction cannula was placed into the c hest cavity in a fixed position. Blood samples were drawn at regular i ntervals for cell count and chemistry. Lactate dehydrogenase values, f or the automatic suction system and the control groups, respectively, expressed as percent of baseline value, were 88 +/- 14 vs 116 +/- 22 a fter 1 hr; 94 +/- 16 vs 123 +/- 23 after 2 hr; and 97 +/- 19 vs 140 +/ - 48 after 3 hr (p < 0.05). Values for free hemoglobin in plasma (perc ent of baseline value), for the automatic suction system and the contr ol groups, respectively, were 102 +/- 18 vs 200 +/- 69 after 1 hr; 98 +/- 29 vs 163 +/- 37 after 2 hr; and 94 +/- 37 vs 179 +/- 42 after 3 h r (p < 0.05). Compared with a standard continuous aspiration system, i n situ regulation of suction significantly reduces blood trauma.