Effects of different modes of cardiopulmonary bypass in patients undergoing cardiac surgery

1. Approved 01/03/2024, Komisiji Republike Slovenije za medicinsko etiko (KME RS) (Štefanova ulica 5, Ljubljana, 1000, Slovenia; +386 (0)1478 69 06; kme.mz@gov.si), ref: 0120-33/2024-2711-3

2. Approved 28/02/2023, Klinicki bolnicki centar Rijeka, Eticko povjerenstvo (Kresimirova 42, Rijeka, 51000, Croatia; +385 (0)51658808; pravna-ivanaa@kbc-rijeka.hr), ref: 2170-29-02/1-23-2

1. Endothelial dysfunction: peak plasma syndecan-1 level measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB.
2. Inflammation: peak plasma IL-6/IL-10 ratio measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB.
3. Oxidative stress: peak plasma malondialdehyde (MDA) measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB.
4. Microcirculation: perfused vessel density (variable of diffusive capacity) measured with GlycoCheck at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB.
5. Clinical outcomes: peak lactate levels measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB.

1. Other markers of endothelial dysfunction, all measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB:
1.1. Heparan sulphate
1.2. Angiopoetin Ang-1 and angiopoetin Ang-2 and Ang-2/Ang-1 ratio
1.3. Endokan
1.4. Syndecan-4
1.5. Glypican-1
1.6. Hyaluronic acid
1.7. Orosomucoid
1.8. Fractalkine
1.9. Von Willebrand factor
1.10. Vascular endothelial growth factor (VEGF)
2. Other markers of inflammation, all measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB:
2.1. IL-6/IL-10 patterns
2.2. IL-10
2.3. IL-6
2.4. IL-5
2.5. IL-16
2.6. IL-8
2.7. MMP-9
2.8. MMP-13
2.9. IL-1β
2.10. IL-7
2.11. IL-17
2.12. IL-18
2.13. IL-18BP

3. Other markers of oxidative stress, all measured with ELISA at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB:
3.1. Reactive oxygen species
3.2. Reactive nitrogen species

4. Other microcirculatory parameters, all measured with GlycoCheck at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB:
4.1. Convective blood flow: proportion of perfused vessels (proportion of perfused vessels = perfused vessel density/total vessel density)
4.2. Variables of diffusive capacity: Total vessel density and De Backer score
4.3. Variable of heterogeneity: Heterogeneity index
4.4. Variable of glycocalyx: Perfused boundary region

5. Clinical outcomes:
Vascular (extracted from patients’ medical records for all):
1. Total dose of NA administered intraoperatively and in ICU until the first discharge or up to 66 h after the end of CPB (mcg/kg)
2. Total dose of V administered intraoperatively and in ICU (IE) until the first discharge or up to 66 h after the end of CPB
3. NA and V maximum rate intraoperatively and in ICU (mcg/kg/min // IE/h) until the first discharge or up to 66 h after the end of CPB
4. NA and V duration of treatment since the end of CPB until the first discharge from ICU or up to 66 h after the end of CPB
5. Frequency of vasoplegic syndrome: defined as MAP lower than 65 mmHg despite preload optimization requiring norepinephrine infusion for more than 4 hours after CPB
6. Fluid administration and fluid balance, defined as for ICU and HDU ([total fluid intake/24h] to blood loss + urine output/ 24h) (mL) and in OR ([total fluid intake anaesthesia + perfusionist/end of surgery] to blood loss + urine output/end of surgery) up to 66 h after the end of CPB
7. Incidence and extent of fluid overload defined as fluid balance > 5% = [fluid intake (L) - fluid output (L)]/body weight (kg) × 100%
8. Patients requiring vasodilator infusion intraoperatively and in ICU up to 66 h after the end of CPB (n, %)
9. NA equivavelents intraoperatively and in ICU (mcg/kg/min) until the first discharge or up to 66 h after the end of CPB

Heart:
1. Patients requiring any inotropic support intraoperatively and in ICU until the first discharge or up to 66 hours after CPB (n, %) [extracted from patients’ medical records]
2. Total dose of inotropes administered intraoperatively and in ICU (IE) until the first discharge or up to 66 h after the end of CPB [extracted from patients’ medical records]
3. Peak hsTnI (ng/L), measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
4. Peak heart-type fatty-acid binding protein, ELISA, measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
5. Peak NT-proBNP (ng/L), measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
6. New-onset atrial fibrillation (n, %) in ICU and in HDU up to 7 days after the end of CPB [extracted from patients’ medical records]
7. Type 5 myocardial infarction : biomarker values above five times the 99th percentile of the normal reference range during the initial 72 hrs following CABG + new pathological Q-waves or new LBBB, or angiographically documented new graft or native coronary artery occlusion, or imaging evidence of new loss of viable myocardium [extracted from patients’ medical records]

Kidney:
1. Urine output intraoperatively (mL/kg/h), in ICU (mL/kg/h) and in HDU (mL/kg/h) [extracted from patients’ medical records]
2. Peak creatinine and maximum change in creatinine from pre-operative (μmol/L), measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
3. Peak urea (mmol/L), measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
4. Creatinine clearance (mL/min), measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
5. Furosemide dose (mg) in ICU and in HDU up to 66 h after the end of CPB [extracted from patients’ medical records]
6. Renal replacement therapy up to 66 h after the end of CPB (n, %) [extracted from patients’ medical records]
7. AKI presence and stage by Kidney Disease Improving Global Outcomes (KDIGO) criteria: stage 1 is defined as an increase in serum creatinine (SCr) by ≥26.5 μmol/L or an increase in SCr to ≥1.5 times baseline, or urine output < 0.5 mL/kg/h for 6−12 h. AKI stage 2 is defined as an increase in SCr to ≥2.0–2.9 times the baseline, or urine output < 0.5  mL/kg/h for ≥12 h. AKI stage 3 is defined as an SCr of up to 3.0 times the baseline or SCr increased to ≥354 μmol/L or the initiation of renal replacement therapy or urine output <0.3 mL/kg/h for ≥24 h or anuria for ≥12 h.

Lungs:
1. Time of mechanical ventilation (intubation to extubation) until the first discharge from ICU or up to 66 h after the end of CPB (extracted from patients’ medical records)
2. Time to extubation from the end of surgery until the first discharge from ICU or up to 66 h after the end of CPB (extracted from patients’ medical records)
3. (Lowest) PaO2/FiO2 level measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB

Liver (all measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB [i.e., the next morning following surgery], 42 hours after CPB and 66 hours after CPB):
1. Concentration of ALT (μkat/L)
2. Concentration of AST (μkat/L)
3. INR
4. Bilirubin μmol/L
5. Concentration of GGT (μkat/L)

Other:
1. Peak CRP (mg/L) measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
2. Peak PCT (μg/L) measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
3. Peak leucocytes count (109 cells per L) measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
4. Lowest BE measured at baseline, 45 minutes after aortic cross-clamp, 2 hours after CPB, 6 hours after CPB, 18 hours after CPB (i.e., the next morning following surgery), 42 hours after CPB and 66 hours after CPB
5. Total heparin given during CPB (IE/kg)
6. Substitution of blood products intraoperatively and up to 66 hours after CPB (total number of packs and volume)
7. Chest tube drainage up to 66 hours after CPB
8. Hemostatic reoperation frequency within 7 days (n, %)
9. Duration of ICU stay
10. Duration of hospital stay

Major complications:
1. Occurrence of major adverse cardiovascular events (MACCE) within the 7 days following cardiac surgery. The criteria for MACCE required the occurrence of at least one outcome among the following: in-hospital mortality, successful resuscitated cardiac arrest, stroke, acute kidney injury, and mesenteric ischemia.
2. Stroke was defined as an embolic, thrombotic, or hemorrhagic cerebral event with persistent residual motor, sensory, or cognitive dysfunction (e.g., hemiplegia, hemiparesis, aphasia, sensory deficit, impaired memory) diagnosed by brain computed tomography scan
3. Additional complications: homeostatic revision surgery, deep sternal wound infection, superficial wound infection

Subgroup analyses:
1. The researchers will split the patients into two groups based on the duration of ACC: the shorter duration group will be compared to the longer duration (50:50 in each group)
2. They will split the patients into two groups based on the elevated AKI risk preoperatively: elevated AKI risk is defined by a score of ≥1.5 points using the following risk score: pre-operative haemoglobin <130 g.l-1 (2 points); pre-operative creatinine >100 μmol.l- 1 (2 points); age >70 years (1.5 points), BMI >30 kg.m-2 (1.5 points) and New York Heart Association (NYHA) status 4 (1.5 points)

CORRELATIONS and ASSOCIATIONS (univariate and multivariable logistic regression analyses) between the collected variables.