Jialin Xing

Superior vena cava drainage improves upper body oxygenation during veno-arterial extracorporeal membrane oxygenation in sheep

IntroductionDifferential hypoxia is a pivotal problem in patients with femoral veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) support. Despite recognition of differential hypoxia and attempts to deliver more oxygenated blood to the upper body, the mechanism of differential hypoxia as well as prevention strategies have not been well investigated.MethodsWe used a sheep model of acute respiratory failure that was supported with femoral VA ECMO from the inferior vena cava to the femoral artery (IVC-FA), ECMO from the superior vena cava to the FA (SVC-FA), ECMO from the IVC to the carotid artery (IVC-CA) and ECMO with an additional return cannula to the internal jugular vein based on the femoral VA ECMO (FA-IJV). Angiography and blood gas analyses were performed.ResultsWith IVC-FA, blood oxygen saturation (SO2) of the IVC (83.6 ± 0.8%) was higher than that of the SVC (40.3 ± 1.0%). Oxygen-rich blood was drained back to the ECMO circuit and poorly oxygenated blood in the SVC entered the right atrium (RA). SVC-FA achieved oxygen-rich blood return from the IVC to the RA without shifting the arterial cannulation. Subsequently, SO2 of the SVC and the pulmonary artery increased (70.4 ± 1.0% and 73.4 ± 1.1%, respectively). Compared with IVC-FA, a lesser difference in venous oxygen return and attenuated differential hypoxia were observed with IVC-CA and FA-IJV.ConclusionsDifferential venous oxygen return is a key factor in the etiology of differential hypoxia in VA ECMO. With knowledge of this mechanism, we can apply better cannula configurations in clinical practice.

The myocardial protective effect of adenosine as an adjunct to intermittent blood cardioplegia during open heart surgery

BACKGROUND Although adenosine (ADO) has been shown to have beneficial effects against tissue injury after myocardial ischaemia, the controversy still remains regarding the optimal timing, dose, temperature, method of ADO administration and duration of exposure to the drug. This study investigates the cardioprotective effect of exogenous ADO pretreatment as an adjunct to 1 mmol l(-1) ADO cold (12 degrees C) blood cardioplegia during heart valve replacement surgery. MATERIALS AND METHODS Thirty patients with rheumatic heart valve disease undergoing heart valve replacement operations were randomly assigned to two groups: group C (n=15) and group A (n=15). Patients in group C were the control group and received antegrade cold (12 degrees C) high-potassium ([K(+)]=20 mol l(-1)) institute blood cardioplegia. The patients in group A received 10-min 100 microgkg(-1)min(-1) ADO pretreatment before application of the aortic cross-clamp and antegrade 1 mmol l(-1) adenosine high-potassium ([K(+)]=20 mol l(-1)) cold (12 degrees C) blood cardioplegia. Clinical outcomes were observed before, during and after the operation. Plasma level markers of myocardial damage: cardiac Troponin I (cTnI), creatine kinase (CK-MB) and inflammatory factors (interleukin (IL)-6 and IL-8) were obtained from serial venous blood samples after induction, 5 min after cross-clamp of aorta, 10 min after clamp-off, 1h after return to ICU and postoperatively 24 h and 48 h. Right atrial samples were harvested before cross-clamp and after clamp-off. RESULTS Heart valve replacement was successful in all patients. There were no differences regarding operative parameters in the two groups. Time to arrest (during cardiolegia perfusion electrocardiography (ECG) change to a line) was shorter in group A compared to group C (19.9+/-4.6s vs 29.3+/-10.6s; p=0.03). Group A also had lower cTnI and IL-8 levels (p=0.03) at 10 min after aortic declamping, and lower IL-6 (p=0.04) at 24h postoperatively as well. Ultrastructural changes were slighter in group A than group C after clamp-off. Compared to group C, post-reperfusion biopsies in group A displayed only slight overall ultrastructural changes, and scored significantly better on mitochondrial damage (group A 2.23+/-0.65 vs group C 2.85+/-0.66) (p=0.04). CONCLUSION Compared with simple cold blood cardioplegia in heart valve replacement patients, ADO pretreatment as an adjunct to 1 mmol l(-1) ADO cold blood cardioplegia may reduce cTnI, IL-6 and IL-8 release, resulting in reduced myocardial injury in ultrastructure after surgery.

Comparison of low molecular weight hydroxyethyl starch and human albumin as priming solutions in children undergoing cardiac surgery

Human albumin is the conventional cardiopulmonary bypass circuit primer. However, it has high manufacturing costs. Crystalloid and colloid solutions have been developed as alternatives, including a new generation of non-ionic hydroxyethyl starch (HES). The efficacy of hydroxyethyl starch with a 130 molecular weight and substitution degree of 0.4 (hydroxyethyl starch 130/0.4) was compared with human albumin for use in cardiopulmonary bypass surgery in American Society of Anesthesiologists’ grade I-II pediatric congenital heart disease patients. Efficacy was evaluated by comparing perioperative hemodynamic parameters, including plasma colloid osmotic pressure, renal function, blood loss, allogeneic blood volumes and plasma volume substitution. The hydroxyethyl starch group exhibited significantly higher preoperative colloid osmotic pressure (p<0.01) and significantly lower operative renal function and postoperative allogeneic blood volumes than the human albumin group. No significant differences were observed in serum creatinine, glucose, hematocrit or lactic acid levels (p>0.05). Our results indicate that hydroxyethyl starch may be a viable alternative to human albumin in pediatric patients undergoing relatively simple cardiopulmonary bypass surgeries.

Preoperative intra-aortic balloon pump improves the clinical outcomes of off-pump coronary artery bypass grafting in left ventricular dysfunction patients.

Severe left ventricular (LV) dysfunction patients undergoing off-pump coronary artery bypass grafting (OPCAB) are often associated with a higher mortality. The efficacy and safety of the preoperative prophylactic intra-aortic balloon pump (IABP) insertion is not well established. 416 consecutive patients with severe LV dysfunction (ejection fraction ≤35%) undergoing isolated OPCAB were enrolled in a retrospective observational study. 191 patients was enrolled in the IABP group; the remaining 225 patients was in control group. A total of 129 pairs of patients were propensity-score matched. No significant differences in demographic and preoperative risk factors were found between the two groups. The postoperative 30-day mortality occurred more frequently in the control group compared with the IABP group (8.5% vs. 1.6%, p = 0.02). There was a significant reduction of low cardiac output syndrome in the IABP group compared with the control group (14% vs. 6.2%, p = 0.04). Prolonged mechanical ventilation (≥48 h) occurred more frequently in the control group (34.9% vs. 20.9%, p = 0.02). IABP also decreased the postoperative length of stay. Preoperative IABP was associated with a lower 30-day mortality, suggesting that it is effective in patients with severe LV dysfunction undergoing OPCAB.

Veno‐Arterial Extracorporeal Membrane Oxygenation Support in Patients Undergoing Aortic Surgery

Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is an option for mechanical support for patients with postcardiotomy cardiogenic shock (PCS). However, the use of VA-ECMO in patients suffering from aortic disease with PCS has not been greatly reported. This is a retrospective review of adult patients undergoing aortic surgery who received VA-ECMO support to treat refractory PCS from August 2009 to May 2016. A total of 36 patients who underwent aortic surgery with VA-ECMO support for refractory PCS were included. Preoperative, perioperative, and postoperative variables were assessed and analyzed for possible correlation with in-hospital mortality. After a mean duration of 3.6 ± 2.9 days, 24 patients (67%) were weaned off VA-ECMO, and 18 patients (50%) were discharged from the hospital. The overall in-hospital mortality was 50%. The main cause of death was multiple organ dysfunction. The survivors had a lower level of preoperative creatine kinase-MB (CK-MB), a higher rate of antegrade cannulation, and a lower lactate level at 12 h, respectively. Relevant factors for in-hospital mortality were retrograde-flow cannulation (odds ratio [OR], 2.49), peak lactate levels greater than 20 mmol/L (OR, 5.0), and preoperative CK-MB greater than 100 IU/L (OR, 6.40). Antegrade cannulation may provide better perfusion and should be emphasized to improve outcomes. Additionally, levels of peak serum lactate and preoperative CK-MB may be relevant factors for in-hospital mortality in aortic patients with PCS.

Effect of increasing mean arterial blood pressure on microcirculation in patients with cardiogenic shock supported by extracorporeal membrane oxygenation.

BACKGROUND Little is known about the effect of mean arterial blood pressure (MAP) augmentation on the microcirculation in cardiogenic-shock patients with peripheral veno-arterial extracorporeal membrane oxygenation (ECMO) support. We investigated the effect of increasing MAP on the microcirculation in cardiogenic-shock patients with ECMO support. METHODS A single-center prospective observational study under taken in ICU patients undergoing ECMO support for post-cardiotomy cardiogenic shock was carried out. Patients with MAP <60 mmHg treated with ECMO support were the study cohort. Inotropic and vasopressor agents (dopamine, dobutamine, norepinephrine or epinephrine) were administered to maintain the MAP at 60-90 mmHg. Hemodynamic and microcirculatory data were obtained at a baseline MAP of <60 mmHg and 1 h after target MAP was reached. As parameters of microcirculation, we measured thenar eminence tissue oxygenation (StO2) and its change during the vessel obstruction test and cerebral tissue oxygenation (rSO2) with near-infrared spectroscopy. RESULTS Seventeen patients were enrolled in the study. MAP of all patients increased and reached predefined therapeutic targets (52 [50-54.5] vs.74 [70-78.5] mmHg; p < 0.001). To obtain these targets, doses of inotropic agents were increased (inotrope score increased from 14 [15.5-28] μg/kg/min; p < 0.001). No obvious changes were observed in thenarmuscleStO2 and cerebral rSO2. Thenar muscle StO2 desaturation slope and resaturation slopes during the vessel obstruction test were also unchanged. CONCLUSIONS Increasing MAP from <60 mmHg to 60-90 mmHg did not affect microcirculation variables in cardiogenic-shock patients with ECMO support.

Clinical evaluation of five commercially available adult oxygenators in terms of pressure drop during normothermic and hypothermic cardiopulmonary bypass

BACKGROUND It is well documented that trans-membrane pressure drop (TMPD) of hollow-fiber membrane oxygenators (HFMO) may lead to hemolysis, damage to platelets, and systemic inflammatory response. The purpose of this study was to evaluate five commercially available adult oxygenators in terms of pressure drop during normothermic and hypothermic cardiopulmonary bypass (CPB). MATERIALS AND METHODS In a clinical setting, 5 different adult HFMOs were tested in terms of TMPDs. Forty patients scheduled for cardiac surgery were enrolled in the study and were divided into 5 groups according to the type of oxygenator used during CPB: group J (Maquet Quardox n=8), group A (Affinity NT n=8), group P (Polystan Safe Maxi n=8), group T (Terumo Capiox SX 18 n=8) and group C (COBE APEX-TM n=8). Clinical parameters were collected during CPB, including mean arterial pressure (MAP), pump flow, temperature, hematocrit, duration of CPB, cross-clamp time and bypass time. TMPDs of pre-oxygenator and post-oxygenator pressures were recorded at the start of systemic cooling (T1), 10 min after stable hypothermia at 30 degrees C (T2), and at termination of rewarming before the end of CPB (T3). RESULTS There were no significant differences among the 5 groups in pump-flow rate, temperature, hematocrit, and mean arterial pressure during CPB. TMPDs of group J were the lowest at different time-points (T1, 30.71 +/- 8.42mmHg; T2, 25.71 +/- 5.41 mmHg; T3, 27.42 +/- 13.01 mmHg). Compared to the other 3 groups (P, C and T groups), TMPDs of groups J and A at various time-points were lower (J group compared with the other three groups (p<0.001). Although TMPDs in groups A, P and T during hypothermia were higher than during normothermia and post-rewarming, there was no significant statistical difference (p> 0.05). CONCLUSIONS These results suggest that the HFMOs in groups J and A produced significantly lower TMPDs and pre- and post-oxygenator extracorporeal circuit pressures during normothermic and hypothermic CPB.