IJCS | Volume 33, Nº3, May / June 2020

239 Table 3 - The volume of post-surgery bleeding from the thoracic drain Bovine UH treated N = 204 Porcine UH treated N = 65 Total N = 269 Externalized blood volume in 2h (mL) Median (min–max) 50.0 (0.0–2,350.0) 0.0 (0.0–1,400.0) 50.0 (0.0–2,350.0) Q1–Q3 0.0–150.0 0.0–50.0 0.0–100.0 Externalized blood volume in 12h (mL) Median (min–max) 250.0 (0.0–9,650.0) 250.0 (0.0–3,000.0) 250.0 (0.0–9,650.0) Q1–Q3 150.0–500.0 100.0–450.0 150.0–500.0 Externalized blood volume in 24h (mL) Median (min–max) 545.0 (0.0–3,150.0) 400.0 (50.0–3,950.0) 510.0 (0.0–3,950.0) Q1–Q3 300.0–800.0 300.0–750.0 300.0–800.0 Postoperative externalized blood volume Median (range) 695.0 (0.0–3,350.0) 800.0 (50.0–4,525.0) 700.0 (0.0–4,525.0) Q1–Q3 425.0–1,012.5 400.0–1,100.0 400.0–1,050.0 Quantitative variables as median (minimum-maximum values) and interquartile range. Q1: percentile 25%; Q3: percentile 75%. Postoperative period: 24-hour period beginning at 7 o’clock in the morning of the day following the day of surgery. Source: prepared by the authors. Table 4 - Activated clotting time (ACT) values Bovine UH treated N = 204 Porcine UH treated N = 65 ACT at baseline Median (min–max) 137.0 (66.0–470.0) 140.5 (80.0–.0) Pre-ECC Median (min–max) 803.0 (324.0–2,000.0) 693.0 (440.0–2,000.0) ECC: 1 st hour dose Median (min–max) 620.0 (155.0–1,800.0) 585.0 (126.0–1,100.0) ECC: 2 nd hour dose Median (min–max) 591.0 (392.0–991.0) 1365.0 (150.0–2,000.0) ECC: 3 rd hour dose Median (min–max) 638.5 (392.0–885.0) 513.0 (489.0–537.0) ACT after protamine Median (min–max) 149.5 (63.0–307.0) 154.0 (95.0–460.0) Results are shown in seconds. Median (minimum–maximum). ACT: Activated clotting time. ECC: extracorporeal circulation. Source: prepared by the authors. Lima et al. Unfractionated bovine heparin safety Int J Cardiovasc Sci. 2020; 33(3):235-242 Original Article mortality, among other complications. 14 Heparin- induced thrombocytopenia is also a severe adverse effect, occurring in 5 to 7 days after continuous use of the drug, increasing the risk of thrombotic phenomena. 15 Therefore, heparin safety must be well established. In this preliminary, descriptive, exploratory, retrospective investigation, thrombocytopenia was the most frequent blood dyscrasia found after surgery using bovine UFH. Postoperative thrombocytopenia in cardiovascular surgery with ECC is expected and usually temporary. 16 Apart from ECC, it can be related to multiple factors including the patient’s age, previous predisposition, surgery duration, type of surgery, need for reoperation, intraoperative and postoperative blood loss, heparin dose, heparin reversibility, hypothermia, circulatory arrest, and low cardiac output. 16,17 Heparin- induced thrombocytopenia is also a possibility, but it needs laboratory confirmation with the presence of heparin-dependent cell-activating anti-PF4/heparin antibodies. 18 In our study, patients undergoing more complicated and prolonged surgery presented blood dyscrasia with bovine UFH, with a higher risk of bleeding, such as Bentall- and D’ Bono surgery (aortic root reconstruction with valve tube and replantation of coronary ostia), two coronary artery bypass grafting surgeries, mitral-aortic valve replacement with coronary artery bypass grafting, mitral-aortic valve replacement, and aortic valve replacement. The literature reports that the duration of ECC is directly related to the risks. 1,16,19,20 The main comorbidity in cardiac surgery is postoperative bleeding. 20 Published results are highly variable as to what is considered an “acceptable” volume of postoperative bleeding. Miana et al., 20 consider 150 mL/hour to be significant postoperative bleeding. 20 According to the Kirklin/Barratt-Boyes table, 21 maximum drainage of 500 ml is allowed in the first hour, 800 ml in