Liver blood flow during cardiac surgery

OBJECTIVE: Impairment of liver blood flow and, therefore, potentially liver function, has important short-term consequences because of the liver's key metabolic importance and role in drug metabolism. The objective of this study was to quantify the effect of cardiac surgery on liver blood flow from before the induction of anaesthesia to 24 hours postoperatively. METHOD: Ten patients with no history of liver impairment, moderate or good left ventricular function, and undergoing routine hypothermic coronary artery bypass graft surgery, were entered into the study. Liver blood flow was determined by the clearance of indocyanine green (ICG), expressed as a percentage disappearance rate (PDR). RESULTS: The mean baseline percentage disappearence rate (PDR) of indocyanine green (ICG) was 19.84 +/- 4.47%/min. This increased marginally to 20.42 +/- 6.67%/min following the induction of anaesthesia, but after 15 min of cardiopulmonary bypass, the PDR fell to 13.51 +/- 3.69%/min; this was significantly lower than all other PDRs measured throughout the study. Prior to extubation, the PDR increased again to 20.01 +/- 3.72%/ min, and this level was maintained at 12 hours (PDR 20.32 +/- 3.53%min) and 24 hours (PDR 20.51 +/- 2.27%/min). CONCLUSION: The induction of anaesthesia and positive pressure ventilation do not affect liver blood flow. Cardiopulmonary bypass at 30 degrees C is associated with a significant reduction in liver blood flow, which returns to normal within 4-6 hours of surgery and remains normal for up to 24 hours after surgery.     

Role of entropy-based neuromonitoring during cardiac surgery

The paper deals with a role of spectral entropy-based neuromonitoring at cardiac surgery. Eighty cardiosurgical patients were examined. The depth of entropy-based anesthesia was monitored in all the patients. The patients enrolled into the study were divided into 2 groups. Anesthesia was carried out in the study group (n=40), by taking into account entropic parameters, and in the control group (n=40) on clinical grounds. Information on entropic parameters in this group was accessible only to an investigator and inaccessible to an anesthesiologist who had made anesthesia. The results of the study indicated that entropy-based neuromonitoring permits more controllable and predictable anesthesia to be achieved, makes an individual adjustment of the doses of sedatives easier for each patient, at the induction of anesthesia particularly, enables hypo- and hyperhypnotic episodes to be timely revealed, thus reducing the frequency of hypo- and hyperdynamic reactions by 2.4 times.     

Noninvasive cardiac output assessment during heart surgery

Objective. To evaluate the reliability of a new noninvasivemethod for the assessment of cardiac output with the partial carbondioxide rebreathing technique. Methods. This technique wasapplied to patients undergoing heart surgery. Values of cardiac indexobtained with this equipment were compared with the artero-venousCO₂ gradient, a reliable index of cardiovascular status.Positive and negative predictive values of the test were assessed.Results. A total of 21 simultaneous measurement of the cardiacindex and of the artero-venous CO₂ gradient were obtained.The positive predictive value of the test was 67% while thenegative predictive value was 100%, indicating that a normalvalue of cardiac index recorded with the rebreathing technique predictswith a good reliability a normal cardiovascular state.Conclusions. Working through a series of mathematical algorithms,accuracy in the computation of cardiac output can be decreased with thisequipment; however, this limitation seems to be outweighed by thesimplicity and non-invasive nature of the methods.     

直视微创心脏小切口手术的护理配合

目的总结直视微创心脏小切口手术的护理配合要点。方法对271例患者实施直视微创心脏小切口手术,做好手术配合并实施相应的护理。结果患者手术顺利,平均体外循环时间（117.3±47．1）min,主动脉阻断时间（82．6±32．1）min。无术后并发症发生,均痊愈出院,住院时间（6．8±2．6）d。围术期及出院后无1例死亡。结论直视微创心脏手术的近期手术效果良好,手术安全性高。术前做好患者配合手术的健康指导,术中做好手术配合是手术成功的重要措施。     

Sleep during hospitalization and recovery after cardiac surgery

Sleep disturbance is common in patients undergoing cardiac surgery and has been recognized for more than 30 years. Research findings suggest that sleep disturbance is a multifactorial process that has many correlates in these patients and persists from the presurgical period throughout recovery. A growing body of literature suggests the importance of sleep for function and well-being of these patients. The research literature is synthesized and implications for future research and practice are discussed.     

Cerebral oximetry during cardiac surgery under extracorporeal circulation

The time course of changes in rSO2 were studied in 58 patients during the uncomplicated course of cardiac operations under extracorporeal circulation (EC) and moderate hypothermia. rSO2 was also compared with central hemodynamic parameters, bioelectrical cerebral activity, and hemoglobin oxygen saturation of the bulb of the internal jugular vein (jbSO2). In the pre- and postperfusion period there was a significant correlation of rSO2 and jbSO2 (p = 0.01), yet with a low correlation coefficient (r = 0.348). During EC, no correlation was found between rSO2 and jbSO2 (p = 0.09, r = 0.386). Changes in rSO2, blood pressure, EEC, body temperature were analyzed in 2 groups of patients at the stages of an operation under EC. Group 1 comprised patients with cardiac valvular apparatus lesions and Group 2 included those with coronary heart disease who differed not only in age, but also in the history of mainly cerebrovascular atherosclerotic lesions, hypertensive disease, myocardial infarction, etc. In patients from both groups, a reduction in rSO2 occurred at the beginning of EC and at the maximum of cooling. But if in Group 1 patients, the significant reductions in rSO2 at the beginning of EC coincided both with that in mean blood pressure (BPmean), as compared to the baseline values (from 75.55 +/- 10.68 to 66.5 +/- 11.73 mm Hg, p = 0.01), and with the change in the frequency spectrum of EEC (a decrease in the frequency of the right edge, as compared to the baseline values, from 20.77 +/- 1.44 to 19.58 +/- 1.14 Hz, p = 0.01), in Group 2 patients, all significant decreases in rSO2 were accompanied only by a significant reduction in BPmean, but without changes in the frequency spectrum of EEG. It should be noted that over the uncomplicated course of an operation all changes in rSO2 were in the normal range of age-related values.     

Blood transfusions recruit the microcirculation during cardiac surgery

BACKGROUND: Perioperative red blood cell transfusions are commonly used in patients undergoing cardiac surgery to correct anemia caused by blood loss and hemodilution associated with cardiopulmonary bypass circulation. The aim of this investigation was to test the hypothesis that blood transfusion has beneficial effects on sublingual microcirculatory density, perfusion, and oxygenation. To this end, sidestream dark field (SDF) imaging and spectrophotometry were applied sublingually before and after blood transfusion during cardiac surgery. STUDY DESIGN AND METHODS: Twenty‐four adult patients undergoing on‐pump cardiac surgery, including coronary artery bypass grafting, cardiac‐valve surgery, or a combination of these two procedures, were included consecutively in this prospective, observational study. Sublingual microcirculatory density and perfusion were assessed using SDF imaging in 12 patients (Group A). Sublingual reflectance spectrophotometry was applied in 12 patients (Group B) to monitor microcirculatory oxygenation and hemoglobin (Hb) concentration. RESULTS: Blood transfusion caused an increase in systemic Hb concentration (p < 0.01) and hematocrit (p < 0.01). At the microcirculatory level, blood transfusion resulted in increased microcirculatory density (from 10.5 ± 1.2 to 12.9 ± 1.2 mm capillary/mm² tissue, p < 0.01) as shown using SDF imaging. In concert with the SDF measurements, spectrophotometry showed that microcirculatory Hb content increased from 61.4 ± 5.9 to 70.0 ± 4.7 AU (p < 0.01) and that microcirculatory Hb oxygen saturation increased from 65.6 ± 8.3% to 68.6 ± 8.4% (p = 0.06). CONCLUSION: In this study we have shown that blood transfusion: 1) improves the systemic circulation and oxygen‐carrying capacity, 2) improves sublingual microcirculatory density but not perfusion velocity, and 3) improves microcirculatory oxygen saturation.     

Influence of methylprednisolone on cytokine balance during cardiac surgery

OBJECTIVE: To determine the influence of methylprednisolone on the cytokine balance during cardiac surgery. DESIGN: Prospective, randomized, nonblinded study. SETTING: University hospital. PATIENTS: Twenty-one patients on cardiopulmonary bypass undergoing aortocoronary bypass surgery. INTERVENTIONS: According to a randomized sequence, the patients either received methylprednisolone (30 mg/kg) [corrected] before cardiopulmonary bypass and before declamping of the aorta (MPS group, n = 11) or received nothing (control group, n = 10). MEASUREMENTS AND MAIN RESULTS: Serum proinflammatory cytokines (interleukin [IL]-8, IL-6) and anti-inflammatory cytokines (IL-10, IL-1ra) were measured by enzyme-linked immunosorbent assays. Serum IL-6 and IL-8 concentrations in the control group (15.2 +/- 4.1 and 14.1 +/- 1.9 pg/mL, preoperatively) increased to 242 +/- 70.1 and 97.3 +/- 18.3 pg/mL at 60 mins after declamping of the aorta (p < .01, p < .01, respectively). The increases were greater than those from 2.5 +/- 0.6 and 2.5 +/- 0.5 pg/mL to 109.5 +/- 29.0 and 33 +/- 4.1 pg/mL in the MPS group for IL-6 and IL-8, respectively. Serum IL-10 concentrations increased significantly 60 mins after declamping of the aorta compared with its preoperative value in the two groups (the control group, from 1.0 +/- 0 to 537.9 +/- 61.7 pg/mL; the MPS group, from 0.3 +/- 0.2 to 654.9 +/- 24 pg/mL [p < .01, p < .01, respectively]). No difference was found between the two groups. Similarly, serum IL-1ra concentrations in the two groups increased the preoperative value in the control group from 304 +/- 120 to 44,374 +/- 14,631 pg/mL and in the MPS group from 616.5 +/- 109.6 to 35,598 +/- 9,074 pg/mL at 60 mins after declamping of the aorta (p < .01, p < .01, respectively). There was no difference between the two groups. CONCLUSIONS: Methylprednisolone reduces the production of IL-6 and IL-8 but not that of IL-10 and IL-1ra. These results suggest that one of the mechanisms of the cytoprotective effect of methylprednisolone may be to make changes in the proinflammatory and anti-inflammatory cytokine balance.     

Cardioplegic strategies to protect the hypertrophic heart during cardiac surgery

Cardioplegic arrest and cardiopulmonary bypass are key triggers of myocardial injury during aortic valve surgery. Cardioplegic ischaemic arrest is associated with disruption to metabolic and ionic homeostasis in cardiomyocytes. These changes predispose the heart to reperfusion injury caused by elevated intracellular reactive oxygen species and calcium. Cardiopulmonary bypass is associated with an inflammatory response that can generate systemic oxidative stress which, in turn, provokes further damage to the heart. Techniques of myocardial protection are routinely applied to all hearts, irrespective of their pathology, although different cardiomypathies respond differently to ischaemia and reperfusion injury. In particular, the efficacy of cardioprotective interventions used to protect the hypertrophic heart in patients with aortic valve disease remains controversial. This review will describe key cellular changes in hypertrophy, response to ischaemia and reperfusion and cardioplegic arrest and highlight the importance of optimising cardioprotective strategies to suit hypertrophic hearts.     

Clinical evaluation of a cutaneous zero-heat-flux thermometer during cardiac surgery

Journal of Clinical Monitoring and Computing - We evaluated the disposable non-invasive SpotOn? thermometer relying on the zero-heat-flux technology. We tested the hypothesis that this...     

Using cerebral oximetry to prevent adverse outcomes during cardiac surgery

We report a case of reduced cerebral oxygenation which had the possibility of leading to an adverse outcome if it had not been detected by the routine use of cerebral oximetry. This case study illustrates that an inadvertent re-adjustment of a single-stage venous cannula within the superior vena cava resulted only in the cerebral oximetry device alerting to a potential problem. All other monitoring devices remained within standard operating parameters, with no deviation throughout the duration of the incident.