pre-CPB Period Research Articles

Determination of Early Diagnostic Biomarkers of Renal Dysfunction After Cardiopulmonary Bypass: miR-21 and miR10a Mediated Postoperative Inflammation

Objective: Acute renal failure (ARF) prevalence is high among patients who undergo cardiopulmonary bypass (CPB), and this condition can only be diagnosed via serum creatinine level (sCr) conventionally within 48 hours. Therefore, we need early novel diagnosis biomarkers to start preventive treatment of ARF. For that reason, we aimed to analyze if plasma miR-21 derived from heart, correlates with kidney- enriched miR-10a during inflammatory IL-6, IL-1β, and TNF-α response in terms of acute renal failure 30 minutes after CPB.
 Methods: Patients (n=46, Female:8 and Male:38), aged 61.08±9.41, who underwent CPB surgery were included. Blood samples were collected during the pre – and post-CPB (30 minutes after CPB). Demographic data of all cases were collected. Quantification of expression levels of miR-21 and miR-10a was done via quantitative PCR (qPCR). Determination of plasma concentration of relevant cytokines, IL-6, IL-1β, and TNF-α was done via ELISA.
 Results: The circulating level of miR-21 during post-CPB period (-11.78±6.98) was significantly higher (p≤0.05) than pre-CPB period (-6.55±7.11), but there was no significant change (p>0.05) in the circulating level of miR-10a between pre – (-12.22±3.55) and post-CPB (-11.60±3.36) periods. When we compared the mean ΔΔCt values of miR-21 and miR-10a, downregulation was observed in the expression level of miR-10a (0.62±3.77) whilst the expression level of miR-21 (-5.22±7.25) was upregulated (p≤0.05). The levels of plasma concentration of IL-6 (2.74±2.50 ng/l) and TNF-α (83.63±9.33 ng/l) were increased during post-CPB period (both were ***p

Reliability of the Minto model for target-controlled infusion of remifentanil during cardiac surgery with cardiopulmonary bypass

BackgroundThe Minto pharmacokinetic model is used for target-controlled infusion of remifentanil. The reliability of this model has never been evaluated during normothermic cardiac surgery with cardiopulmonary bypass (CPB). The aim of this study was to assess the predictive performance of the model during CPB to determine its reliability during cardiac surgery. MethodsThis was a single-centre observational study. Arterial blood samples were drawn at five time points: T1, after tracheal intubation; T2, immediately before CPB; T3, 10 min after starting CPB; T4, 45 min after starting CPB; T5, 10 min after weaning off CPB. Prediction error (PE) and absolute prediction error (APE) were calculated for each sample and used to determine median prediction error (MDPE) and median absolute prediction error (MDAPE) per patient. Risk factors for APE >30% were assessed using multivariable analysis. Results are presented as medians with inter-quartile ranges. ResultsFifty-eight patients with 283 blood samples (110 during CPB) were included. In the pre-CPB period, MDPE and MDAPE were –17.3 [–32.9 to 2.3] and 24.6 [12–37.7]%, whereas during CPB, they were –1.8 [–15.6 to 11.1] and 14.0 [6.74–27.1]%, respectively. There was no statistically significant difference between measured and predicted remifentanil plasma concentrations during CPB. Age, preoperative albumin concentrations, temperature, and haemodilution were not independently associated with MDAPE >30%. ConclusionsThe Minto model accurately predicts plasma remifentanil concentrations during cardiac surgery with CPB. Clinical trial registration2017-A03153-50.

Age Difference of the Relationship Between Cerebral Oxygen Saturation and Physiological Parameters in Pediatric Cardiac Surgery with Cardiopulmonary Bypass: Analysis Using the Random-Effects Model.

Recently, monitoring of cerebral oxygen saturation (ScO2) has become widespread in pediatric cardiac surgery. Our previous study reported that mean blood pressure (mBP) was the major contributor to ScO2 throughout cardiac surgery with cardiopulmonary bypass (CPB) in children weighing under 10kg. We speculated that this result might be attributable to incomplete cerebral autoregulation in such young children. Accordingly, our hypothesis is that the relationship between ScO2 and the physiological parameters may change according to the growth of the children. ScO2 was measured with an INVOS 5100C (Somanetics, Troy, MI). Random-effects analysis was employed with ScO2 as a dependent variable, and seven physiological parameters (mBP, central venous pressure, nasopharyngeal temperature, SaO2, hematocrit, PaCO2, and pH) were entered as independent covariates. The analysis was performed during the pre-CPB, CPB, and post-CPB periods by dividing the patients into two groups: infants (Infant Group) and children who were more than 1year old (Child Group). The Infant and Child Groups consisted of 28 and 21 patients. In the random-effects analysis, mBP was the major contributor to ScO2 during CPB in both groups. During the pre-CPB period, the effect of mBP was strongest in the Infant group. However, its effect was second to that of SaO2 in the Child Group. During the post-CPB period, SaO2 and mBP still affected ScO2 in the Infant group. However, the dominant contributors were unclear in the Child Group. Cerebral autoregulation may be immature in infants. In addition, it may be impaired during CPB even after 1 year of age.

The impact of urine flow on urine oxygen partial pressure monitoring during cardiac surgery.

Urine oxygen partial pressure (PuO2) may be useful for assessing acute kidney injury (AKI) risk. The primary purpose of this study was to quantify the ability of a novel urinary oxygen monitoring system to make real-time PuO2 measurements intraoperatively which depends on adequate urine flow. We hypothesized that PuO2 data could be acquired with enough temporal resolution to provide real-time information in both AKI and non-AKI patients. PuO2 and urine flow were analyzed in 86 cardiac surgery patients. PuO2 data associated with low (< 0.5 ml/kg/hr) or retrograde urine flow were discarded. Patients were excluded if > 70% of their data were discarded during the respective periods, i.e., during cardiopulmonary bypass (CPB), before CPB (pre-CPB), and after CPB (post-CPB). The length of intervals of discarded data were recorded for each patient. The median length of intervals of discarded data were compared between AKI and non-AKI patients and between surgical periods. There were more valid PuO2 data in CPB and post-CPB periods compared to the pre-CPB period (81% and 90% vs. 31% of patients included, respectively; p < 0.001 and p < 0.001). Most intervals of discarded data were < 3minutes during CPB (96%) and post-CPB (98%). The median length was < 25s during all periods and there was no significant difference in the group median length of discarded data intervals for AKI and non-AKI patients. PuO2 measurements were acquired with enough temporal resolution to demonstrate real-time PuO2 monitoring during CPB and the post-CPB period. NCT03335865, First Posted Date: Nov. 8th, 2017.

Intraoperative Transesophageal Echocardiography to Evaluate Pediatric Patients Undergoing Atrial Septal Defect Procedure

Introduction: Atrial septal defects (ASD) are a type of congenital heart disease that are characterized by a communication between the left atrium with the right atrium. Preoperative intraoperative transesophageal echocardiography (TEE) evaluates cardiac anatomy and function. The objective of this paper was to compare the use of intraoperative TEE in corrective surgeries for ASD in pediatric patients. Material and Methods: After approval by the local Ethics Committee for Research, a retrospective descriptive study was conducted in children aged 3 to 18 years who underwent an ASD repair between January 2011 and January 2015 divided in two groups: TEE group (n=24) and No-TEE group (n=28). Were assessed the demographic data, Qp/Qs ratio, pulmonary hipertension (PH), left ventricle ejection fraction (EF), and major clinical outcomes. Results: There were differences between the two groups in demographics data in age and wieght that were higher in the No-TEE group. There were no differences between the two groups in pulmonary infection, renal dysfunction, congestive heart failure, time of extubation in the ICU and intra-hospital mortality. There was 4% atrial arrhythmias in the TEE group and 0% in the No-TEE group (p=0.46). The No-TEE group showed more time to wean from CPB (35.1 ± 17.3 minutes vs 43.6 ± 27.2 minutes; p=0.01) and more time to release from ICU than TEE-group (42 ± 13.2 hours vs 58.9 ± 30.4 hours, p=0.01). Conclusions: We concluded that the use of intraoperative TEE is safe and economically feasible. It enables an assessment of cardiac anatomy and functions in the pre-CPB period and guide the weaning from CPB with lower time of CPB and ICU length stay than No-TEE group.

Clevidipine compared with nitroglycerin for blood pressure control in coronary artery bypass grafting: a randomized double-blind study

We tested the hypothesis that clevidipine, a rapidly acting dihydropyridine calcium channel blocker, is not inferior to nitroglycerin (NTG) in controlling blood pressure before cardiopulmonary bypass (CPB) during coronary artery bypass grafting (CABG). In this double-blind study from October 4, 2003 to April 26, 2004, 100 patients undergoing CABG with CPB were randomized at four centres to receive intravenous infusions of clevidipine (0.2-8μg·kg(-1)·min(-1)) or NTG (0.4μg·kg(-1)·min(-1) to a clinician-determined maximum dose rate) from induction of anesthesia through 12hr postoperatively. The study drug was titrated in the pre-CPB period with the aim of maintaining mean arterial pressure (MAP) within ±5mmHg of a clinician-predetermined target. The primary endpoint was the area under the curve (AUC) for the total time each patient's MAP was outside the target range from drug initiation to the start of CPB, normalized per hour (AUCMAP-D). The predefined non-inferiority criterion for the primary endpoint was a 95% confidence interval (CI) upper limit no greater than 1.50 for the geometric means ratio between clevidipine and NTG. Total mean [standard deviation (SD)] dose pre-bypass was 4.5 (4.7)mg for clevidipine and 6.9 (5.4)mg for NTG (P<0.05). The geometric mean AUCMAP-D for clevidipine was 283mmHg·min·hr(-1) (n=45) and for NTG was 292mmHg·min·hr(-1) (n=48); the geometric means ratio was 0.97 (95% CI 0.74 to 1.27). The geometric mean AUCMAP-D during aortic cannulation was 357.7mmHg·min·hr(-1) for clevidipine compared with 190.5mmHg·min·hr(-1) for NTG. Mean (SD) heart rate with clevidipine was 76.0 (13.8) beats·min(-1) compared with 81.5 (14.4) beats·min(-1) for NTG. There were no clinically important differences between groups in adverse events. During CABG, clevidipine was not inferior to NTG for blood pressure control pre-bypass.

Evaluation of closed‐loop anesthesia delivery for propofol anesthesia in pediatric cardiac surgery

The objective of this study was to compare the feasibility of closed-loop anesthesia delivery with manual control of propofol in pediatric patients during cardiac surgery. Forty ASA II-III children, undergoing elective cardiac surgery under cardiopulmonary bypass (CPB) in a tertiary care hospital, were randomized to receive propofol either through a closed-loop anesthesia delivery system (CL group) or through traditional manual control (manual group) to achieve a target BIS of 50. Patients were induced and subsequently maintained with a propofol infusion. The propofol usage and the efficacy of closed-loop system in controlling BIS within ±10 of the target were compared with that of manual control. The maintenance of BIS within ±10 of target and intraoperative hemodynamic stability were similar between the two groups. However, induction dose of propofol was less in the CL group (2.06±0.79mg·kg(-1) ) than the manual group (2.95±1.03mg·kg(-1) ) (P=0.006) with less overshoot of BIS during induction in the closed-loop group (P=0.007). Total propofol used in the off-CPB period was less in the CL group (6.29±2.48mg·kg(-1) h(-1) vs 7.82±2.1mg·kg(-1) h(-1) ) (P=0.037). Phenylephrine use in the pre-CPB period was more in the manual group (16.92±10.92μg·kg(-1) vs 5.79±5.98μg·kg(-1) ) (P=0.014). Manual group required a median of 18 (range 8-29) dose adjustments per hour, while the CL group required none. This study demonstrated the feasibility of closed-loop controlled propofol anesthesia in children, even in challenging procedures such as cardiac surgery. Closed-loop system needs further and larger evaluation to establish its safety and efficacy.

Heparin Concentration–Based Anticoagulation for Cardiac Surgery Fails to Reliably Predict Heparin Bolus Dose Requirements

Hemostasis management has evolved to include sophisticated point-of-care systems that provide individualized dosing through heparin concentration-based anticoagulation. The Hepcon HMS Plus system (Medtronic, Minneapolis, MN) estimates heparin dose, activated clotting time (ACT), and heparin dose response (HDR). However, the accuracy of this test has not been systematically evaluated in large cohorts. We examined institutional databases for all patients who underwent cardiac surgery with cardiopulmonary bypass (CPB) at our institution from February 2005 to July 2008. During this period, the Hepcon HMS Plus was used exclusively for assessment of heparin dosing and coagulation monitoring. Detailed demographic, surgical, laboratory, and heparin dosing data were recorded. ACT, calculated and measured HDR, and heparin concentrations were recorded. Performance of the Hepcon HMS Plus was assessed by comparison of actual and target ACT values and calculated and measured HDR. In 3880 patients undergoing cardiac surgery, heparin bolus dosing to a target ACT resulted in wide variation in the postheparin ACT (r(2) = 0.03). The postheparin ACT did not reach the target ACT threshold in 7.4%(i.e., when target ACT was 300 s) and 16.9% (i.e., when target ACT was 350 s) of patients. Similarly, the target heparin level calculated from the HDR did not correlate with the postbolus heparin level, with 18.5% of samples differing by more than 2 levels of the assay. Calculated and measured HDR were not linearly related at any heparin level. The Hepcon HMS Plus system poorly estimates heparin bolus requirements in the pre-CPB period. Further prospective studies are needed to elucidate what constitutes adequate anticoagulation for CPB and how clinicians can reliably and practically assess anticoagulation in the operating room.

Blood Concentrations of Enflurane Before, During, and After Hypothermic Cardiopulmonary Bypass

The purpose of this study was to determine blood concentrations of enflurane delivered via a membrane oxygenator during hypothermic cardiopulmonary bypass (CPB) with changes in the input enflurane concentration and temperature and to characterize the pharmacokinetics of enflurane washout during and after CPB. Blood enflurane concentrations were measured by gas chromatography before, during, and after CPB by using mean delivered enflurane concentrations of 0.5% v/v (group 1, n = 5), 0.8% (group 2, n = 7), and 1% (group 3, n = 14). The investigation was performed in a teaching hospital setting. Twenty-six patients undergoing cardiac surgery requiring hypothermic CPB. Variations in input enflurane concentration in different patients plus blood sampling from the arterial side of the circuit for enflurane assay. Median (25th and 75th percentiles) pre-CPB blood enflurane concentrations were 48 (25-50) mg/L, 52 (47-56) mg/L, and 115 (90-143) mg/L in groups 1 (0.5% v/v), 2 (0.8% v/v), and 3 (1% v/v), respectively. During hypothermia (28 degrees C) corresponding enflurane concentrations were 44 (31-53) mg/L, 56 (45-62) mg/L, and 145 (109-203) mg/L, respectively. For groups 1 and 2, there were no significant changes in blood enflurane compared with the corresponding pre-CPB value. However, for group 3, cooling resulted in a significant increase (p = 0.006) in blood enflurane. In all groups, enflurane concentrations after rewarming were similar to those in the pre-CPB period. It is concluded that exposure to enflurane concentrations greater than 0.8% during CPB can result in high blood concentrations.

Factors Affecting the Difference between Radial and Femoral Arterial Pressure after Cardiopulmonary Bypass in Patients Undergoing Valvular ReplacementFactors Affecting the Difference between Radial and Femoral Arterial Pressure after

Background: After cardiopulmonary bypass (CPB), the radial arterial pressure is often lower than that of the femoral artery. If this difference is overlooked, the patients might be treated with unnecessary vasoconstrictors or inotropes. However, the exact etiology or mechanism of this discrepancy is not known. If a patients group with the risk of a high pressure gradient after CPB could be predicted, the femoral arterial pressure from pre-CPB period might be monitored in order to not be inadequately managed after weaning from CPB. We studied the predicting factors of this phenomenon in patients undergoing a valvular replacement. Methods: One hundred patients undergoing valvular replacement were included in this study. The radial and femoral arterial pressures were measured in the same monitoring system during entire procedure of the operation. The radial to femoral arterial pressure ratio (R/F) was calculated. Demographic data and hemodynamic variables after induction of anesthesia were studied using correlation analysis to assess which data could be associated with R/F. A best predictive model was developed with stepwise multiple linear regression analysis Results: Correlation analysis showed that age, preoperative ejection fraction (EF), and cardiac index after induction were statistically significant. A predictive model was developed including age and preoperative EF. The regression equation is R/F = 86.249 - (0.294 age) + (0.329 preoperative EF). Conclusions: It could be predicted in the patients with old age or low preoperative ejection fraction that radial arterial pressure might be lower than that of femoral artery in a valvular replacement operation.

Does isoflurane optimize myocardial protection during cardiopulmonary bypass?

Objective: To investigate the possible myocardial protective effect of isoflurane during aortic cross-clamp and cardioplegic cardiac arrest in patients undergoing conventional coronary artery bypass graft surgery. Design: Prospective, randomized. Setting: University medical center. Participants: Forty-nine patients undergoing elective coronary artery bypass graft surgery divided into 2 groups: control group (n = 21) and isoflurane group (n = 28). Intervention: Isoflurane was administered in the pre-cardiopulmonary bypass (CPB) period to the isoflurane group. Measurements And Main Results: Hemodynamics and ST- segment variations were monitored in the pre-CPB period and after weaning from CPB in both groups. Incidence of reperfusion arrhythmias after release of aortic cross-clamp was compared. In the isoflurane group, the mean cardiac index after CPB was significantly higher than the pre-CPB value, whereas no difference between the 2 values was found in the control group. The higher cardiac index in the isoflurane group was associated with a lesser degree of ST- segment changes than in the control group. There was no significant difference between the 2 groups in the incidence of reperfusion arrhythmias after release of aortic cross-clamp. Conclusion: The present report suggests that administration of isoflurane before aortic cross-clamping in patients undergoing coronary artery bypass graft surgery may optimize the myocardial protective effect of cardioplegia. Isoflurane may be particularly advantageous whenever prolonged periods of aortic cross-clamping or inadequate delivery of cardioplegia is expected. Copyright © 2001 by W.B. Saunders Company

Measurement of Coronary Sinus Flow Using Transesophageal Echocardiography in patients Undergoing Coronary Artery Bypass Grafting

Study Objective: To measure coronary sinus blood flow during coronary artery bypass graft (CABG) with transesophageal echocardiography (TEE). Design: Prospective study. Setting: Elective cardiac surgery at a university hospital. Patients: Thirty-one ASA physical status III and IV adult patients free of significant coexisting disease and undergoing CABG. Intervention: We measured coronary sinus blood flow velocity by using TEE and hemodynamic variables, before and after cardiopulmonary bypass (CPB) and after CPB. Measurements and Main Results: We obtained a complete set of control measurements for 29 subjects (94%) and a complete set of post-CPB measurements in 28 patients (90%). In the normal group, peak velocity, and velocity time integral (VTI) of coronary sinus blood flow in the post-CPB period increased significantly compared with the pre-CPB period with CABG (n = 23). In the group of new regional wall motion abnormalities in the post-CPB period, peak velocity and VTI of coronary sinus blood flow in the post-CPB period did not increase significantly compared with the pre-CPB period by CABG (n = 5). Conclusions: We were able to measure the coronary sinus flow velocity by pulse-Doppler TEE during CABG. The peak velocity and VTI of coronary sinus blood flow in the post-CPB period increased significantly compared with in the pre-CPB period by CABG. The results of this preliminary study show the feasibility of clinical evaluation of CABG intraoperatively.

Induction and maintenance of anaesthesia with sevoflurane in comparison to high dose opioid during coronary artery bypass surgery

Induction and maintenance of anaesthesia with sevoflurane in comparison to high dose opioid during coronary artery bypass surgery

Effects of hypothermic and normothermic cardiopulmonary bypass on brain oxygenation

Background. In this study, we assessed the effects of normothermia and hypothermia during cardiopulmonary bypass (CPB) both on internal jugular venous oxygen saturation (SjvO2) and the regional cerebral oxygenation state (rSO2) estimated by near infrared spectroscopy (NIRS).Methods. Thirty patients scheduled for elective coronary artery bypass graft surgery (CABG) were randomly divided into two groups. Group 1 (n = 15) underwent surgery for normothermic (> 35°C) CPB, and group 2 (n = 15) underwent surgery for hypothermic (30°C) CPB, and alpha-stat regulation was applied. A 4.0-French fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor the SjvO2 value. To estimate the rSO2 state, a spectrophotometer probe was attached to the mid-forehead. SjvO2 and rSO2 values were then collected simultaneously using a computer.Results. Neither the cerebral desaturation time (duration during SjvO2 value below 50%), nor the ratio of the cerebral desaturation time to the total CPB time significantly differed (normothermic group: 18 ± 6 min, 15 ± 6%; hypothermic group: 17 ± 6 min, 13 ± 6%, respectively). The rSO2 value in the normothermic group decreased during the CPB period compared with the pre-CPB period. The rSO2 value in the hypothermic group did not change throughout the perioperative period.Conclusions. These findings suggest that near infrared spectroscopy might be sensitive enough to detect subtle changes in regional cerebral oxygenation.

Comparison of isoflurane and midazolam as hypnotic supplementation to moderately high-dose fentanyl during coronary artery bypass grafting: Effects on systemic hemodynamics and early postoperative recovery profile

Objective: The aim of this study was to compare isoflurane and midazolam as hypnotic adjuncts to moderately high-dose fentanyl during coronary artery bypass grafting (CABG) with regard to perioperative hemodynamics and early postoperative recovery profile. Design: Prospective open randomized clinical trial. Setting: Single university-affiliated medical center. Participants: Thirty patients scheduled for elective primary CABG were randomly divided into two groups receiving either isoflurane or midazolam as adjuncts to 50 μg/kg of fentanyl. Intervention: Anesthesia was induced with intravenous fentanyl, 10 μg/kg, and midazolam, 0.1 mg/kg, and maintained with either isoflurane, 0.6%, or midazolam, 0.1 mg/kg/ hour, in intravenous infusion. Before the sternotomy, all patients received 30 μg/kg of fentanyl. Midazolam and isoflurane were stopped at the start of cardiopulmonary bypass (CPB). At rewarming, all patients received fentanyl, 5 to 10 μg/kg, and either isoflurane, 0.6%, or midazolam, at a reduced rate of 0.05 mg/kg/h. Changes in systolic blood pressure of more than 20% from baseline were first treated with vasoactive drugs. Hypertension was corrected with ketanserin, 10 to 20 mg; hypotension with ephedrine, 5 mg. For a mean blood pressure of less than 50 mmHg during CPB phenylephrine, 0.25 to 0.5 mg, was administered. When hypotension persisted despite a vasopressor, the administration of midazolam or isoflurane was stopped. Postoperatively, the patients were mechanically ventilated overnight and sedated with intermittent doses of fentanyl, 0.15 mg, and midazolam, 5 mg. Measurements and Main Results: Routine five-lead electro-cardiogram (ECG) and invasive hemodynamic monitoring using a pulmonary artery catheter were performed. The mean dose of fentanyl was 3.9 mg in the midazolam group versus 3.6 mg in the isoflurane group. There were no significant perioperative differences between groups in cardiac output, filling, or pulmonary artery pressures. Systolic blood pressure from the initial incision to CPB was lower in the isoflurane group compared with the midazolam group. During this interval, ketanserin was required in nine patients from the midazolam group at a mean dose of 26 mg, compared with only one patient in the isoflurane group. During and after CPB, there was no difference in ketanserin and in vasopressive/inotropic agent requirements. Temporary cessation of midazolam was required in four patients, for a mean of 34 minutes; whereas isoflurane was stopped in 10 patients for 36 minutes, mostly in the post-CPB period. Time to awakening and to extubation in the midazolam group (217 minutes and 19.5 hours) and the isoflurane group (193 minutes and 18.2 hours) were comparable. Between intensive care unit (ICU) admission and extubation, the patients in the midazolam group received 0.89 mg of fentanyl and 36.5 mg of midazolam compared with 0.98 mg of fentanyl and 36.2 mg of midazolam in the isoflurane group. There was a tendency for a higher postoperative pulmonary shunt and more severely impaired oxygenation in the isoflurane group. Conclusion: Midazolam supplementation to fentanyl required more frequent antihypertensive escape during the pre-CPB period than isoflurane. However, more frequent cessation of isoflurane caused by hypotension was needed in the post-CPB period. No difference in awakening and ICU discharge was found.

Antithrombin III during cardiac surgery: effect on response of activated clotting time to heparin and relationship to markers of hemostatic activation.

This study was designed to determine if, and to what extent, antithrombin III (AT) levels affect the response of the activated clotting time (ACT) to heparin in concentrations used during cardiac surgery, and to characterize the relationship between AT levels and markers of activation of coagulation during cardiopulmonary bypass (CPB). After informed consent, blood specimens obtained from eight normal volunteers (Phase I) were used to measure the response of the kaolin and celite ACT to heparin after in vitro addition of AT (200 U/dL) and after dilution with AT-deficient plasma to yield AT concentrations of 20, 40, 60, 80, and 100 U/dL. In Phase II, blood specimens collected before the administration of heparin and prior to discontinuation of CPB, were used to measure the response of the kaolin ACT to heparin (preheparin only), AT concentration, and a battery of coagulation assays in 31 patients undergoing repeat or combined cardiac surgical procedures. In Phase I, strong linear relationships were observed between kaolin (slope = 1.04 AT - 2, r2 = 0.78) and celite (slope = 1.36 AT + 6, r2 = 0.77) ACT slopes and AT concentrations below 100 U/dL. In the pre-CPB period of Phase II, only factors V (partial r = -0.49) and VIII (partial r = -0.63) were independently associated with heparin-derived slope using multivariate analysis; an inverse relationship was observed between AT and fibrinopeptide A levels (r = -0.41) at the end of CPB. Our findings indicate that the responsiveness of whole blood (ACT) to heparin at the high concentrations used with CPB is progressively reduced when the AT concentration decreases below 80 U/dL. Because AT is variably, and sometimes extensively, reduced in many patients before and during CPB, AT supplementation in these patients might be useful in reducing excessive thrombin-mediated consumption of labile hemostatic blood components, excessive microvascular bleeding, and transfusion of blood products. Heparin, a drug with anticoagulant properties, is routinely given to patients undergoing cardiac surgery to prevent clot formation within the cardiopulmonary bypass circuit. However, when levels are reduced, heparin is not as effective. Findings within this study indicate that administration of antithrombin III may help to preserve the hemostatic system during cardiopulmonary bypass.

The use of the iSTAT portable analyzer in patients undergoing cardiopulmonary bypass.

To evaluate the utility of the iSTAT blood analyzer, a bedside device for hematocrit, sodium, potassium, and glucose measurement during cardiopulmonary bypass (CPB). Forty patients scheduled for elective CPB were evaluated prospectively. In addition to using the iSTAT analyzer, blood samples were analyzed at four time points: following induction of anesthetic, 10 min. after initiation of CPB, 60 min. after initiation of CPB, and following heparin neutralization by protamine. Blood glucose concentration was measured by the hospital laboratory using a Kodak Analyzer and by a glucose meter, electrolytes were evaluated by the Kodak Analyzer and BGE (a device which is commonly used for "satellite laboratory" determinations of electrolyte and blood gas results), and hematocrit samples were measured by the hospital laboratory using an NE 8,000 and a centrifuge. The means and standard deviations of the differences between the methods were calculated. The hematocrit values determined by the iSTAT machine, when adjusted for the level of total protein (according to manufacturer's directions), differed from the laboratory values by 0.53 +/- 1.46 percentage points. An alternative to measuring total protein and making the adjustment is simply adding 1% to the hematocrit in the pre-CPB period and 3% on-CPB or post-CPB, which we found to yield values that differed from the laboratory by 0.52 +/- 1.42 percentage points. For all four tests (hematocrit, sodium, potassium, and glucose) the iSTAT had a similar relationship to the laboratory values as did the other commonly used means (centrifuge, BGE, and glucose meter) of clinical evaluation. In summary, we found that in patients undergoing CPB, the iSTAT values agreed sufficiently well with standard laboratory values and that the iSTAT instrument can be relied upon for bedside measurements.

Hypotension Resistant to Therapy with alpha Receptor Agonists Complicating Cardiopulmonary Bypass

Hypotension Resistant to Therapy with alpha Receptor Agonists Complicating Cardiopulmonary Bypass

The Effects of Nitrous Oxide on Left Ventricular Systolic and Diastolic Performance Before and After Cardiopulmonary Bypass

We investigated the effects of nitrous oxide (N2 O) on central hemodynamics and left ventricular systolic and diastolic function in 25 patients undergoing coronary artery bypass surgery.All patients were receiving beta-blockers and had good left ventricular function. Global and regional systolic left ventricular performance and diastolic function were determined by computer-assisted analysis of transesophageal echocardiographic (TEE) images, and mitral Doppler flow profiles, respectively. The patients were anesthetized with fentanyl and ventilated with oxygen in air. Hemodynamic and TEE measurements were obtained before and after the introduction of N2 O in oxygen (60%/40%), before and after cardiopulmonary bypass (CPB). N2 O reduced mean arterial pressure, heart rate, stroke volume, and cardiac output both before and after CPB. Left ventricular global area ejection fraction (GAEF) was not changed by the introduction of N2 O, either before or after CPB. N2 O induced a significant change in regional wall motion after, but not before CPB, as assessed by the relationship between segmental area ejection fraction (SAEF) and GAEF. Analysis of the mitral flow profile indicated an increase in early diastolic relaxation in the pre-CPB period after introduction of N2 O, that was absent in the post-CPB period. We conclude that N2 O induces regional wall motion abnormalities and possibly diastolic dysfunction post-CPB. (Anesth Analg 1995;81:243-8)

The effects of nitrous oxide on left ventricular systolic and diastolic performance before and after cardiopulmonary bypass: evaluation by computer-assisted two-dimensional and Doppler echocardiography in patients undergoing coronary artery surgery.

We investigated the effects of nitrous oxide (N2O) on central hemodynamics and left ventricular systolic and diastolic function in 25 patients undergoing coronary artery bypass surgery. All patients were receiving beta-blockers and had good left ventricular function. Global and regional systolic left ventricular performance and diastolic function were determined by computer-assisted analysis of transesophageal echocardiographic (TEE) images, and mitral Doppler flow profiles, respectively. The patients were anesthetized with fentanyl and ventilated with oxygen in air. Hemodynamic and TEE measurements were obtained before and after the introduction of N2O in oxygen (60%/40%), before and after cardiopulmonary bypass (CPB). N2O reduced mean arterial pressure, heart rate, stroke volume, and cardiac output both before and after CPB. Left ventricular global area ejection fraction (GAEF) was not changed by the introduction of N2O, either before or after CPB. N2O induced a significant change in regional wall motion after, but not before CPB, as assessed by the relationship between segmental area ejection fraction (SAEF) and GAEF. Analysis of the mitral flow profile indicated an increase in early diastolic relaxation in the pre-CPB period after introduction of N2O, that was absent in the post-CPB period. We conclude that N2O induces regional wall motion abnormalities and possibly diastolic dysfunction post-CPB.