Mauro Cotza

Surgical Reexploration After Cardiac Operations: Why a Worse Outcome?

BACKGROUND Surgical reexploration due to postoperative bleeding occurs in 2% to 6% of cardiac surgical patients and is accompanied by increased morbidity and mortality. In this study, we addressed the postoperative course of patients needing surgical reexploration, with specific respect to the timing of reexploration and the transfusional needs as determinants of morbidity and mortality. METHODS This was a retrospective study of 232 patients having undergone surgical reexploration owing to postoperative bleeding after cardiac operations, compared with a control, propensity-matched group. RESULTS Patients in the surgical reexploration group had greater morbidity (low cardiac output, acute renal failure, sepsis) and longer mechanical ventilation time and intensive care unit stay than did control patients, and a significantly higher mortality rate (14.2% versus 3.4%, p = 0.001). The timing of surgical reexploration was not associated with morbidity or mortality. The amount of packed red cells transfused was significantly associated with increased morbidity (acute renal failure, low cardiac output syndrome, sepsis), with mechanical ventilation time and intensive care unit stay, and with the mortality rate (0.25% increase for each unit transfused). CONCLUSIONS The main determinant of morbidity and mortality for patients requiring a surgical reexploration after cardiac operations is the amount of packed red cells transfused. Delaying the timing of reexploration may represent a risk factor only when the delay creates the need for an excessive use of allogeneic blood products, or in the presence of clinical signs of cardiac tamponade.

Different patterns of heparin resistance: therapeutic implications.

Heparin resistance (HR) during cardiac operations is a common feature. Its aetiology often recognizes a decrease in circulating antithrombin III (AT III) due to a preoperative heparin treatment. Nevertheless, some papers highlighted the existence of HR in patients with normal values of AT III. This paper was designed in order to identify this subgroup of AT III-independent heparin-resistant patients. Five hundred consecutive patients scheduled for coronary revascularization with cardiopulmonary bypass were enrolled in this prospective trial. HR was identified in 104 (20.8%) patients. Thirty-six of them (7.2% of the total population) had a preoperative AT III activity ≥100%, and were defined as AT III-independent heparin-resistant patients. This subgroup significantly differs from the AT III-dependent heparin-resistant group being affected by a less severe degree of HR and including less patients pretreated with heparin. Unlike the other heparin-resistant patients, these subjects do not respond to AT III supplementation aimed at reaching supranormal AT III activity values.

Determinants of antithrombin consumption in cardiac operations requiring cardiopulmonary bypass

Antithrombin (AT) is a natural anticoagulant that is consumed during cardiac operations with cardiopulmonary bypass (CPB). This study is an observational trial aimed at identifying the factors determining the magnitude of the AT consumption during cardiac operations. Two hundred and fifty consecutive adult patients undergoing cardiac operations with CPB were admitted to the study. Preoperative and intraoperative variables were tested with respect to their role in determining AT activity at the end of the operation. At a univariate analysis, eight predictors of AT activity at the end of the operation have been identified: preoperative AT activity; age; diabetes on medication; preoperative haematocrit value; preoperative dialysis; combined operation; CPB duration; lowest temperature on CPB. A multivariate predictive model was created, and five factors remained as independent predictors of AT activity at the end of the operation: preoperative AT activity (p = 0.001); age (p = 0.015); combined operation (p = 0.014); diabetes (p = 0.013) and CPB duration (p = 0.001). On this basis, predictive tables of AT consumption have been established for different combinations of risk factors.

Effects of priming volume reduction on allogeneic red blood cell transfusions and renal outcome after heart surgery

Introduction: Excessive hemodilution during cardiopulmonary bypass (CPB) is associated with an increased rate of red blood cell (RBC) transfusion and acute kidney injury (AKI). Minimization of the oxygenator priming volume is a measure to contain hemodilution. In this study, we evaluated the new oxygenator, Sorin Inspire 6™, with respect to its ability to limit hemodilution, RBC transfusion rate and postoperative AKI rate. Methods: A retrospective study on a consecutive series of 1,724 adult patients receiving heart surgery with CPB. Patients treated with the Inspire 6™ were assigned to the low priming volume oxygenator (LPVO) group (N=383) and patients treated with conventional oxygenators to the conventional group (N=1,341). Dynamic priming volume, time course of the hematocrit, RBC transfusions and AKI rate were compared between the groups. Results: Priming volume was significantly (p=0.001) lower in the LPVO group (624±113 mL) vs. the conventional group (775±150 mL), with higher values of hematocrit during and after CPB. After correction for other confounders, patients in the LPVO group had a significantly lower RBC transfusion rate (odds ratio 0.68, 95% confidence interval 0.52-0.90, p=0.006) and AKI rate (odds ratio 0.55, 95% confidence interval 0.32-0.93, p=0.032). Conclusion: The Inspire 6™ oxygenator allows a significant containment of hemodilution during CPB, reducing the risk of RBC transfusions and postoperative AKI.

Hemodilution on Cardiopulmonary Bypass as a Determinant of Early Postoperative Hyperlactatemia

Objective The nadir hematocrit (HCT) on cardiopulmonary bypass (CPB) is a recognized independent risk factor for major morbidity and mortality in cardiac surgery. The main interpretation is that low levels of HCT on CPB result in a poor oxygen delivery and dysoxia of end organs. Hyperlactatemia (HL) is a marker of dysoxic metabolism, and is associated with bad outcomes in cardiac surgery. This study explores the relationship between nadir HCT on CPB and early postoperative HL. Design Retrospective study on 3,851 consecutive patients. Measurements and Main Results Nadir HCT on CPB and other potential confounders were explored for association with blood lactate levels at the arrival in the Intensive Care Unit (ICU), and with the presence of moderate (2.1 – 6.0 mMol/L) or severe (> 6.0 mMol/L) HL. Nadir HCT on CPB demonstrated a significant negative association with blood lactate levels at the arrival in the ICU. After adjustment for the other confounders, the nadir HCT on CPB remained independently associated with moderate (odds ratio 0.96, 95% confidence interval 0.94-0.99) and severe HL (odds ratio 0.91, 95% confidence interval 0.86-0.97). Moderate and severe HL were significantly associated with increased morbidity and mortality. Conclusions Hemodilution on CPB is an independent determinant of HL. This association, more evident for severe HL, strengthens the hypothesis that a poor oxygen delivery on CPB with consequent organ ischemia is the mechanism leading to hemodilution-associated bad outcomes.

Heparin-like effect in postcardiotomy extracorporeal membrane oxygenation patients

IntroductionUnfractionated heparin (UFH) is the anticoagulant of choice for extracorporeal membrane oxygenation (ECMO), but bivalirudin can be used as an alternative. The purpose of the present study is to investigate the existence of a heparin-like effect (HLE) during heparin-free ECMO.MethodsThis is a retrospective study on patients treated with ECMO and receiving bivalirudin as the sole anticoagulant. Thromboelastography (TEG) tests with and without heparinase were recorded during the ECMO duration. A total of 41 patients (22 pediatrics and 19 adults) treated with ECMO after cardiac surgery procedures and receiving only bivalirudin-based anticoagulation were studied. Based on the presence of a different reaction time (R-time) between the TEG test with heparinase or without heparinase we defined the presence of a HLE. Survival to hospital discharge, liver failure, sepsis, bleeding and transfusion rate were analyzed for association with HLE with univariate tests.ResultsHLE was detected in 56.1% of the patients. R-times were significantly shorter in tests done with heparinase versus without heparinase during the first seven days on ECMO. Patients with HLE had a significantly (P = 0.046) higher rate of sepsis (30%) than patients without HLE (5.6%) at a Pearsons chi-square test.ConclusionsA heparin-like effect is common during ECMO, and most likely due to a release of heparinoids from the glycocalyx and the mast cells, as a consequence of sepsis or of the systemic inflammatory reaction triggered by the contact of blood with foreign surfaces.

Gabexate mesilate and antithrombin III for intraoperative anticoagulation in heparin pretreated patients

Thirty patients scheduled for elective myocardial revascularization and having undergone preoperative heparin treatment have been admitted to this prospective, randomized study. The aim of the study was to test two different strategies for preserving circulating antithrombin III (AT-III) during cardiopulmonary bypass. Patients in the control group (group C, n = 10) were treated with a standard heparinization (300 IU/kg). Patients in group A (n = 10) received the same management plus two doses of purified antithrombin III (1000 IU each). Patients in group GA received 200 IU/kg heparin and a continuous infusion of heparin (100 IU/kg/h) and gabexate mesilate (2 mg/kg/h) plus the same dose of antithrombin III as group A. Both group A and group GA demonstrated a preservation of circulating AT-III when compared to group C; this effect was more pronounced in group GA. The total heparin dosage was less in group GA than in groups A and C. Purified AT-III administration is recommended in heparin pretreated patients; the addition of gabexate mesilate to this protocol decreases the heparin requirement and increases the AT-III preservation.

Modern ECMO: why an ECMO programme in a tertiary care hospital

Extracorporeal Membrane Oxygenation (ECMO) represents a useful tool to support the lungs and the heart when all conventional therapies failed and the patients are at risk of death. While the Extracorporeal Life Support Organization (ELSO) collects data from different institutions that joined the Registry and reports overall outcome, individual centres often collide with results below expectations, either in adults and in paediatric population. Some authors suggest that poor outcomes could be overcome with a programme dedicated to ECMO, with specialized professionals adequately trained on ECMO and with a consistent number of procedures. In 2012, The IRCCS PSD ECMO Programme was instituted with the specific aim of achieving better results than hitherto obtained. After only 1 year of activity, the results justified the programme, with a better survival rate for each group investigated, particularly in adults, but surprisingly in paediatrics too, where the results were better than what reported by ELSO. Although the number of patients treated with ECMO is still growing up, the effects of the ECMO programme continue to exert a positive action on outcome even now. The present article reports data on survival, blood loss, and blood consumption during ECMO in the last few years at our institution.

Carbon dioxide production during cardiopulmonary bypass: pathophysiology, measure and clinical relevance:

Carbon dioxide production during cardiopulmonary bypass derives from both the aerobic metabolism and the buffering of lactic acid produced by tissues under anaerobic conditions. Therefore, carbon dioxide removal monitoring is an important measure of the adequacy of perfusion and oxygen delivery. However, routine monitoring of carbon dioxide removal is not widely applied. The present article reviews the main physiological and pathophysiological sources of carbon dioxide, the available techniques to assess carbon dioxide production and removal and the clinically relevant applications of carbon dioxide-related variables as markers of the adequacy of perfusion during cardiopulmonary bypass.