Cardiac output and cerebral blood flow during carotid surgery in regional versus general anesthesia: A prospective randomized controlled study.

OBJECTIVE: Carotid endarterectomy (CEA) is a preventive procedure aimed at decreasing the subsequent risk of fatal or disabling stroke in patients with significant carotid stenosis. It is well-known that carotid surgery under ultrasound-guided regional anesthesia (US-RA) causes a significant increase in blood pressure, heart rate and stress hormone levels owing to increased sympathetic activity. However, little is known about the effects on cardiac output (CO), cardiac index (CI), and cerebral blood flow (CBF) under US-RA as compared with general anesthesia (GA). METHODS: Patients scheduled for CEA were randomized prospectively to receive US-RA (n = 37) or GA (n = 41). The primary end point was the change in CI after induction of anesthesia and the change from baseline over time at four different times during the entire procedure in the respective randomized US-RA and GA groups. In addition to systolic blood pressure and heart rate, we also recorded peak systolic velocity, end-diastolic velocity, and minimum diastolic velocity as seen from transcranial Doppler ultrasound examination, as well as regional cerebral oxygenation (rSO2) as seen from near-infrared refracted spectroscopy to evaluate cerebral blood flow. RESULTS: In the US-RA group, the CI increased after induction of anesthesia (3.7 ± 0.8 L/min/m2) and remained constant until the end of the procedure. In the GA group CI was significantly lower (2.4 ± 0.6 L/min/m2; P < .001). After induction of anesthesia, the rSO2 remained constant in the GA group on both the ipsilateral (63 ± 9 rSO2) and the contralateral (65 ± 7 rSO2) sides; in contrast, it significantly increased in the US-RA group (ipsilateral 72 ± 8 rSO2; P < .001; contralateral 72 ± 6 rSO2; P < .001). The transcranial Doppler ultrasound parameters (peak systolic velocity, end-diastolic velocity, and minimum diastolic velocity) did not differ between the US-RA and the GA group. The clinical outcome was similarly favorable for both groups. CONCLUSIONS: CI was maintained near baseline values throughout the procedure during US-RA, whereas a significant decrease in CI values was observed during CEA under GA. Near-infrared refracted spectroscopy values, reflecting blood flow in small vessels, were higher in US-RA patients than in those with GA. These differences did not influence clinical outcome.

Administration of fibrinogen concentrate combined with prothrombin complex maintains hemostasis in children undergoing congenital heart repair (a long-term propensity score-matched study).

BACKGROUND: Bleeding is a common problem in children with congenital heart disease undergoing major cardiac surgery requiring cardiopulmonary bypass (CPB). Little is known about optimal management with blood products. OBJECTIVE: To investigate clinical outcome and hemostatic effects of fibrinogen concentrate (FC) in combination with prothrombin complex concentrate (PCC) versus standard treatment with fresh frozen plasma (FFP) in children undergoing cardiac surgery. METHODS: For this single-institution cohort study, data on 525 children were analyzed. Propensity score matching in 210 children was applied to reduce the impact of various baseline characteristics. RESULTS: Three children treated with FC/PCC developed surgical site bleeding requiring surgical revision. One child developed central venous line-related thrombosis. Blood loss through chest tube drainage was independent of FC/PCC. Coagulation abnormalities were not present in any of these children. Time to extubation and ICU stay did not differ. In the FC/PCC group, children received (median, Q1, Q3) 52 mg/kg (32, 83) FC and 28IU/kg (13, 44) PCC. Fibrinogen concentration was comparable at baseline. On admission to the ICU, fibrinogen was higher in children receiving FC/PCC, namely, 232 mg/dL (196, 280), than in children receiving FFP (186 mg/dL, 149, 224; P < .001). On discharge from the ICU, values did not differ ((FC/PCC 416 mg/dL (288, 501)), non-FC/PCC 418 mg/dL (272, 585; P = 1.000)). CONCLUSION: FC/PCC was well tolerated and permitted hemostasis to be maintained, even in the very young. We were not able to detect a signal for inferiority of this treatment. We conclude that FC/PCC can safely replace FFP.

Guided vs. non-guided insertion of Ambu AuraGain™ in edentulous patients.

BACKGROUND: Supraglottic airway devices perform more poorly and have lower oropharyngeal leak pressure in edentulous patients than in patients with teeth. The Ambu Aura Gain is a newer second generation supraglottic airway device. OBJECTIVE: This randomized clinical trial assessed the oropharyngeal leak pressure in edentulous patients using the Ambu Aura Gain with a gastric tube for insertion guidance and without insertion guidance. MATERIAL AND METHODS: Patients with ASA (American Society of Anesthesiology) physical status I-III were recruited. Primary outcome was oropharyngeal leak pressure after insertion. Secondary outcome parameters were oropharyngeal leak pressure 15 min and 30 min after insertion, insertion time, insertion attempts and glottis view through flexible fiberscope. RESULTS: In this study 72 patients aged between 51 and 90 years (mean 73 years) were randomly allocated to the "with guidance" (n = 36) or the "without guidance" group (n = 36). Mean (SD) oropharyngeal leak pressure in "with guidance" and "without guidance" group was 24 cm H2O and 24 cm H2O (ns), respectively. A difference was found in mean insertion time with guidance versus without guidance group 52 s (45 s) vs. 26 s (15 s) (p < 0.001). No difference was found in any of the other secondary outcome parameters. CONCLUSION: A guided insertion technique does not improve oropharyngeal leak pressure of the Ambu AuraGain™ in edentulous patients. As the only difference is an increase in insertion time this technique is of no benefit for this population.

Functional Recovery of a Human Neonatal Heart After Severe Myocardial Infarction.

RATIONALE: Cardiac remodeling and subsequent heart failure remain critical issues after myocardial infarction despite improved treatment and reperfusion strategies. Recently, cardiac regeneration has been demonstrated in fish and newborn mice after apex resection or cardiac infarctions. Two key issues remain to translate findings in model organisms to future therapies in humans: what is the mechanism and can cardiac regeneration indeed occur in newborn humans? OBJECTIVE: To assess whether human neonatal hearts can functionally recover after myocardial infarction. METHODS AND RESULTS: Here, we report the case of a newborn child having a severe myocardial infarction due to coronary artery occlusion. The child developed massive cardiac damage as defined by serum markers for cardiomyocyte cell death, electrocardiograms, echocardiography, and cardiac angiography. Remarkably, within weeks after the initial ischemic insult, we observed functional cardiac recovery, which translated into long-term normal heart function. CONCLUSIONS: These data indicate that, similar to neonatal rodents, newborn humans might have the intrinsic capacity to repair myocardial damage and completely recover cardiac function.

Prolonged extracorporeal membrane oxygenation for pediatric necrotizing pneumonia due to Streptococcus pneumonia and influenza H1N1 co-infection: how long should we wait for native lung recovery?

Most children with severe respiratory failure require extracorporeal membrane oxygenation (ECMO) for 7-10 days. However, some may need prolonged duration ECMO (> 14 days). To date, no consensus exists on how long to wait for native lung recovery. Here we report the case of a 3-year-old boy who developed severe necrotizing pneumonia requiring venovenous (VV) ECMO after 19 days of mechanical ventilation. In the first 4 weeks of his ECMO run, he showed no lung aeration, requiring total extracorporeal support. However, after we started strategies for promoting lung recovery such as daily prone positioning and regular use of toilet bronchoscopy and inhalative DNAse to clear secretions, by week five his tidal volumes gradually increased and he was successfully decannulated after 43 days. Moreover, we decided not to proceed to a surgical removal of the necrotic lung area. At present, he is 1-year post discharge and has fully recovered. This report shows that unexpected native lung recovery is possible even after prolonged loss of lung function and that a previous healthy lung can recover from apparent irreversible lung injury.

Predicting Transfusion Requirements During Extracorporeal Membrane Oxygenation.

OBJECTIVE: Patients requiring extracorporeal membrane oxygenation (ECMO) have a well-known bleeding risk and the potential for experiencing possibly fatal thromboembolic complications. Risk factors and predictors of transfusion requirements during ECMO support remain uncertain. The authors hypothesized that compromised organ function immediately before ECMO support will influence transfusion requirements. DESIGN: A prospective observational study. SETTING: A tertiary, single-institutional university hospital. PARTICIPANTS: The study included 40 adult patients requiring ECMO for intractable cardiac and respiratory failure between July 2010 and December 2012. Blood samples were taken before initiation of ECMO (baseline), after 24 and 48 hours on ECMO, and 24 hours after termination of ECMO. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Independent of veno-arterial or veno-venous support, 26% of patients required≥2 packed red blood cells per day (PRBC/d) and 74% of patients required<2 PRBC/d during ECMO. Requirements of≥2 PRBC/d during ECMO support were associated with higher creatinine levels and lower prothrombin times (PT, %) at baseline and with impaired platelet function after 24 hours on ECMO. Platelet function, activated by thrombin receptor-activating peptide stimulation, decreased by 30% to 40% over time on ECMO. Receiver operating characteristic curve analysis showed cut-off values for creatinine of 1.49 mg/dL (sensitivity 70%, specificity 70%; area under the curve [AUC] 0.76, 95% confidence interval [CI] 0.58-0.94), for PT of 48% (sensitivity 80%, specificity 59%; AUC 0.69, 95% CI 0.50-0.87), and for thrombin receptor-activating peptide (TRAP) 32 U (sensitivity 90%, specificity 68%; AUC 0.76, 95% CI 0.59-0.93). CONCLUSIONS: The results of this study demonstrated that increased creatinine levels and lower PT before ECMO and secondary impaired platelet function significantly increased transfusion requirement.

Ultrasound-guided regional anesthesia for carotid endarterectomy induces early hemodynamic and stress hormone changes.

OBJECTIVE: Locoregional anesthesia is an effective method for evaluating cerebral function during carotid endarterectomy (CEA). Landmark-guided regional anesthesia (RA) is currently used for CEA and can provoke substantial perioperative hypertension. Ultrasound-guided RA (US-RA) is a new method for performing RA in CEA; however, the effect on sympathetic activity and blood pressure is uncertain. This study assessed early sympathetic activity during CEA in US-RA compared with general anesthesia (GA). METHODS: Patients were prospectively randomized to receive US-RA (n = 32) or GA (n = 28) for CEA. The primary end point was the change in systolic arterial blood pressure after induction of anesthesia (just before starting surgery) comparing US-RA with GA. We also recorded heart rate and analyzed concentrations of plasma blood hormones, including cortisol, metanephrine, and normetanephrine at five different times. Creatinine kinase, troponin I, and N-terminal pro-B-type natriuretic peptide were analyzed to detect potential changes in cardiac biomarkers during the procedure. RESULTS: Systolic arterial blood pressure (mean ± standard deviation) increased significantly in US-RA patients compared with GA patients even before surgery was initiated (180 ± 26 mm Hg vs 109 ± 24 mm Hg; P < .001), then remained elevated during the entire surgery and returned to baseline values 1 hour after admission to the postoperative anesthesia care unit. Heart rate (US-RA: 78 ± 16 beats/min, GA: 52 ± 12 beats/min; P < .001) and cortisol levels (US-RA: 155 ± 97 µg/L, GA: 99 ± 43 µg/L; P = .006) were also significantly higher in the US-RA group after induction of anesthesia. Other values did not differ. CONCLUSIONS: The US-RA technique for CEA induces temporary intraoperative hypertension and an increase in stress hormone levels. Nevertheless, US-RA is a feasible, effective, and safe form of locoregional for CEA that enables targeted placement of low volumes of local anesthesia under direct visualization.

Extracorporeal membrane oxygenation induces short-term loss of high-molecular-weight von Willebrand factor multimers.

BACKGROUND: High-molecular-weight (HMW) von Willebrand factor (vWF) multimers are crucial for primary hemostasis. Increased shear stress from ventricular assist devices can provoke premature degradation of HMW vWF multimers. Whether similar loss of vWF multimers occurs during extracorporeal membrane oxygenation (ECMO) is not clear. METHODS: We conducted a prospective observational study in a clinical cohort of patients who required ECMO for intractable cardiac and/or respiratory failure. The primary end point was the quantity and quality of HMW vWF multimer bands before, during, and after ECMO support. To investigate further changes in primary hemostasis, we also measured vWF antigen activity (vWF:Ag), vWF ristocetin cofactor activity (vWF:RCo), and factor VIII in 38 patients who required ECMO support before initiation of ECMO (baseline), after 24 and 48 hours on ECMO, and 24 hours after termination of ECMO therapy. RESULTS: Compared with baseline, vWF:Ag and vWF:RCo decreased after 24 hours of ECMO (mean ± SD, vWF:Ag, 307% ± 152% to 261% ± 138%, P = 0.002; vWF:RCo 282% ± 145% to 157% ± 103%, P < 0.0001) and remained lower during ongoing support (vWF:Ag 265% ± 128%, P = 0.025; vWF:RCo 163% ± 94%, P < 0.0001). After termination of ECMO, vWF:Ag was greater than baseline (359% ± 131%, P = 0.004) and vWF:RCo was similar to baseline levels (338% ± 142%, P = 0.046). Compared with baseline, the calculated vWF:RCo/vWF:Ag ratio decreased after 24 hours on support (0.96 ± 0.23 to 0.61 ± 0.17, P ≤ 0.0001) and remained lower during 48 hours on ECMO (0.63 ± 0.18, P ≤ 0.0001). After termination of ECMO support (0.94 ± 0.19, P = 0.437), values rapidly returned to baseline. The number of HMW vWF multimers (n) decreased from baseline after 24 hours on ECMO (21 ± 1.4 to 14 ± 1.8, P ≤ 0.0001) and after 48 hours on ECMO (15 ± 2.1, P ≤ 0.0001). Twenty-four hours after termination of ECMO support, HMW vWF multimeric pattern had returned to baseline values (21 ± 1.8, P = 0.551). CONCLUSIONS: Loss of HMW vWF multimer bands occurred in patients undergoing ECMO support and resolved after the termination of ECMO. Although not detectable with coagulation screening tests, a vWF:RCo/vWF:Ag ratio <0.7 during ECMO was highly indicative for loss of HMW vWF multimers. Our findings may at least in part explain increased bleeding tendency during ECMO therapy. Administration of vWF concentrates may support restoration of primary hemostasis in patients with relevant bleeding during ECMO support.

Hemorrhagic Shock: Blood Marker Sequencing and Pulmonary Gas Exchange.

BACKGROUND: The early identification of internal hemorrhage in critically ill patients may be difficult. Besides circulatory parameters, hemoglobin and lactate concentration, metabolic acidosis and hyperglycemia serve as laboratory markers for bleeding. In this experiment, we examined pulmonary gas exchange in a porcine model of hemorrhagic shock. Moreover, we sought to investigate if a chronological order of appearance regarding hemoglobin, lactatemia, standard base excess/deficit (SBED) and hyperglycemia exists in early severe hemorrhage. METHODS: In this prospective, laboratory study, twelve anesthetized pigs were randomly allocated to exsanguination or a control group. Animals in the exsanguination group (n = 6) endured a 65% blood loss over 20 min. No intravenous fluids were administered. Measurements were taken before, immediately after, and at 60 min after the completed exsanguination. Measurements included pulmonary and systemic hemodynamic variables, hemoglobin concentration, lactate, base excess (SBED), glucose concentration, arterial blood gases, and a multiple inert gas assessment of pulmonary function. RESULTS: At baseline, variables were comparable. Immediately after exsanguination, lactate and blood glucose were increased (p = 0.001). The arterial partial pressure of oxygen was increased at 60 min after exsanguination (p = 0.04) owing to a decrease in intrapulmonary right-to-left shunt and less ventilation-perfusion inequality. SBED was different to the control only at 60 min post bleeding (p < 0.001). Hemoglobin concentration did not change at any time (p = 0.97 and p = 0.14). CONCLUSIONS: In experimental shock, markers of blood loss became positive in chronological order: lactate and blood glucose concentrations were raised immediately after blood loss, while changes in SBED lagged behind and became significant one hour later. Pulmonary gas exchange is improved in shock.

Loss or Dilution-A New Diagnostic Method to Assess the Impact of Dilution on Standard Laboratory Parameters.

Intraoperative fluid therapy is regularly used in patients undergoing cardiac surgery procedures with cardiopulmonary bypass (CPB). Although fluid administration has several advantages, it unavoidably leads to hemodilution. The hemodilution may further influence the interpretation of concentration-based laboratory parameters like hemoglobin (Hgb), platelet count (PLT) or prothrombin time (PT). These all parameters are commonly used to guide blood product substitution. To assess the impact of dilution on these values, we performed a prospective observational study in 174 patients undergoing elective cardiac surgery. We calculated the total blood volume according to Nadler's formula, and fluid therapy was correlated with a newly developed dilution coefficient formula at the end of CPB. Intravenously applied fluids were measured from the beginning of the anesthesia (baseline, T0) and 15 min after the end of protamine infusion (end of CPB, T1). The amount of the administered volume (crystalloids or colloids) was calculated according to the percentage of the intravascular fluid effect, and intraoperative diuresis was further subtracted. The median blood volume increased by 148% in all patients at T1 compared to the calculated total blood volume at T0. This led to a dilution-dependent decrease of 38% in all three parameters (Hgb 24%, corrCoeff = 0.53; PLT 41%, corrCoeff = 0.68; PT 44%, corrCoeff = 0.54). The dilution-correlated decrease was significant for all parameters (p < 0.001), and the effect was independent from the duration of CPB. We conclude that the presented calculation-based approach could provide important information regarding actual laboratory parameters and may help in the guidance of the blood product substitution and potential transfusion thresholds. Further research on the impact of dilution and related decision-making for blood product substitution, including its impact on morbidity and mortality, is warranted.

The Pulmonary Artery Catheter in the Perioperative Setting: Should It Still Be Used?

The pulmonary artery catheter (PAC) was introduced into clinical practice in the 1970s and was initially used to monitor patients with acute myocardial infarctions. The indications for using the PAC quickly expanded to critically ill patients in the intensive care unit as well as in the perioperative setting in patients undergoing major cardiac and noncardiac surgery. The utilization of the PAC is surrounded by multiple controversies, with literature claiming its benefits in the perioperative setting, and other publications showing no benefit. The right interpretation of the hemodynamic parameters measured by the PAC and its clinical implications are of the utmost essence in order to guide a specific therapy. Even though clinical trials have not shown a reduction in mortality with the use of the PAC, it still remains a valuable tool in a wide variety of clinical settings. In general, the right selection of the patient population (high-risk patients with or without hemodynamic instability undergoing high-risk procedures) as well as the right clinical setting (centers with experience and expertise) are essential in order for the patient to benefit most from PAC use.

How mechanical circulatory support helps not to need it--new strategies in pediatric heart failure.

During the past 3 years, seven potential candidates for mechanical circulatory support (MCS) were treated at our center. Ultimately, only one of them needed MCS (extracorporeal membrane oxygenation [ECMO] for 16 days), although 5 years earlier, all would have been considered for MCS at our center. Seven consecutive patients were seen in this period: four toddlers (three suffering from fulminant myocarditis and one with dilated cardiomyopathy associated with spongy myocardium) and three adolescents (two with postmyocarditis cardiomyopathy and one with hypertrophic cardiomyopathy and severe restrictive dysfunction after an ischemic event with cardiopulmonary resuscitation [stunned heart]). All patients presented in acute cardiocirculatory decompensation. All were admitted to the intensive care unit (ICU); all but one were sedated and intubated. A combination of levosimendan, milrinone, and nesiritide was administered to all patients. Use of catecholamines was kept short (<48 h in six individuals). MCS (ECMO, Berlin Heart Excor Pediatric, and Heartware) was always available. MCS initiation was indicated in only one patient, who was developing progressive multiorgan failure (MOF). The three toddlers with myocarditis recovered with complete normalization of myocardial function within 6 months. The fourth toddler is still at the ICU while waiting for transplantation. The three adolescents were listed with high urgency for heart transplantation, and all received a graft within 3 weeks. The adolescent with the stunned heart developed progressive MOF and was successfully supported with ECMO until transplantation. All six patients with completed course were discharged home in New York Heart Association Heart Failure Functional Classification System I condition without neurological deficits. Combined use of levosimendan, milrinone, and nesiritide, avoidance of catecholamines as much as possible, and MCS as backup are the new strategies at our center. This cardioprotective approach gives excellent outcome at lower risk and better cost-effectiveness in our pediatric patients with acute heart failure. Pediatric trials are recommended to evaluate combined use of newer cardioprotective drugs.

Anesthesia-Induced Oxidative Stress: Are There Differences between Intravenous and Inhaled Anesthetics?

Agents used for the induction of anesthesia have been shown to either promote or mitigate oxidative stress. A fine balance between the presence of reactive oxygen species (ROS) and antioxidants is crucial for the proper normal functioning of the cell. A basal concentration of ROS is essential for the manifestation of cellular functions, whereas disproportionate levels of ROS cause damage to cellular macromolecules such as DNA, lipids, and proteins, eventually leading to necrosis and apoptosis. Increased ROS has been linked with numerous illnesses, such as cardiovascular, immune system, liver, and kidney, and has been shown to promote cancer and accelerate aging. Knowledge of the various pharmacologic agents that increase or reduce oxidative stress may promote a safer way of inducing anesthesia. Furthermore, surgery itself leads to increased ROS production and ischemia/reperfusion injury. Indeed, increased perioperative oxidative stress has been correlated with increased postoperative complications and prolonged recovery. Anesthesiologists care for patients during the whole spectrum of perioperative care and thus are in a unique position to deliver countermeasures to oxidative stress. Using preferentially an induction agent which reduces oxidative stress might lead to better clinical outcomes and fewer postoperative complications. Propofol has been shown in several studies to reduce oxidative stress, which reduces postoperative complications and leads to a faster recovery, and thus might represent the preferred induction agent in the right clinical setting.

Quality of life improvement after robotically assisted coronary artery bypass grafting.

OBJECTIVES: Coronary artery bypass grafting (CABG) is associated with long rehabilitation periods and slow quality of life (QOL) improvement. Totally endoscopic coronary artery bypass grafting (TECAB) can be performed using robotic technology and remote access perfusion. The aim of this study was to evaluate whether TECAB leads to accelerated QOL improvement as compared to standard CABG. METHODS: We included 120 patients who had received robotically assisted CABG, 56 of whom were operated on using standard sternotomy. These patients were compared to 55 patients who underwent the TECAB procedure and to 9 TECAB patients who required conversion to conventional sternotomy. QOL evaluation was performed before the operation and 1, 3 and 6 months after the procedure using the SF-36 health survey and a standardized questionnaire. RESULTS: All quality of life aspects improved significantly in all study patients. At 3 months, TECAB patients showed significantly better QOL scores related to bodily pain and physical health. Hospital stay and time to restoration of daily activities were significantly shorter. Converted patients experienced similar courses to sternotomy patients in terms of QOL. CONCLUSIONS: TECAB using robotic technology leads to improved physical health, shorter hospital stay and a more rapid restoration of daily activities. Conversion from TECAB to sternotomy does not lead to QOL impairment as compared to primary sternotomy.

Thromboembolic complications during weaning from right ventricular assist device support.

We report on two patients who experienced life-threatening thromboembolic complications during prolonged weaning from Levitronix CentriMag right ventricular assist device support. Right ventricular assist device flow in both patients was reduced below 2 L/min for a period of 72 or 36 h to closely monitor patients' hemodynamics and echocardiography because the extent of right ventricular recovery was difficult to assess. Thrombus formation occurred despite adjusting the heparin dosage to achieve partial prothrombin time values between 60 and 70 s. Periods of reduced flow during Levitronix CentriMag support must be kept short, and an additional bolus dose of heparin should be considered.

Detection of protamine and heparin after termination of cardiopulmonary bypass by thrombelastometry (ROTEM): results of a pilot study.

BACKGROUND: Our goal of this study was to determine whether protamine's effects on coagulation can be detected and differentiated from those of heparin when using thrombelastometry (ROTEM). METHODS: To reverse the effects of heparin after cardiopulmonary bypass (CPB), 22 consecutive patients undergoing aortocoronary bypass graft surgery were included. According to clinical routine, all patients received a first dose of protamine calculated from the total amount of heparin given; additional protamine (70 U/kg) was administered to patients with activated clotting time (ACT) above baseline and clinical signs of diffuse bleeding. Simultaneously, routine ACT measurements, ROTEM assays (heparin-sensitive INTEM, and heparinase-containing HEPTEM test) and standard coagulation tests were performed, and the activity of coagulation factors as well as antifactor Xa activity measured. RESULTS: Administration of additional protamine (n = 16) resulted in a statistically significant increase in coagulation times on the intrinsically activated test (INTEM-CT), namely from (mean [+/-SD]) 219.8 (+/-19.1) s to 241.1 (+/-21.7) s (P < 0.001), and on the heparinase-containing test (HEPTEM-CT), namely from 210.2 (+/-19.9) s to 226.8 (+/-21.8) s (P < 0.001). These changes were not observed in patients receiving a single protamine dose (n = 6). The INTEM-CT:HEPTEM-CT ratio correctly identified 56 of the 58 samples as not containing residual heparin and correctly detected residual heparin in 3 of the only 6 samples showing elevated antifactor Xa values after CPB. CONCLUSION: Our preliminary data show that at termination of CPB administration of additional protamine results in a brief prolongation of coagulation times on the INTEM and HEPTEM test and that ROTEM might be useful in excluding residual heparin in cases showing prolonged ACT.

An assessment of cardiopulmonary bypass-induced changes in platelet function using whole blood and classical light transmission aggregometry: the results of a pilot study.

BACKGROUND: In this study, we explored whether antiplatelet medications impair whole blood impedance aggregometry after cardiac surgery and cardiopulmonary bypass (CPB) compared with classical light transmission aggregometry (LTA). METHODS: Multiplate (M) assays measuring changes in electrical resistance as aggregation units over time, and LTA assays (% aggregation) induced by collagen (COL), adenosine diphosphate (ADP), or arachidonic acid were performed simultaneously using arterial blood samples obtained before induction of anesthesia, 15 min and 3 h after neutralization of heparin in 70 consecutive patients scheduled for elective coronary artery bypass grafting. Patients in Group A (n = 48) discontinued intake of antiplatelet drugs for at least 7 days and served as controls, patients in Group B (n = 11) received aspirin 100 mg/d and those in Group C (n = 11) aspirin 100 mg/d and clopidogrel 75 mg/d (dual antiplatelet therapy) until the day before surgery. RESULTS: In patients without antiplatelet therapy, 15 min and 3 h after protamine a significant decrease in platelet aggregation was observed with all three agonists and both aggregation methods. In patients receiving aspirin alone, LTA-COL, LTA-ADP and M-ADP changed significantly over time, and ADP assays of both aggregation methods showed a significant decrease in platelet aggregation 15 min after protamine in patients receiving dual antiplatelet therapy. When calculating the areas under the receiver-operating characteristic curves for discrimination of antiplatelet agents, LTA-COL was able to discriminate between controls and patients receiving aspirin or dual antiplatelet therapy 15 min and 3 h after CPB and the M-ADP assay was able to discriminate between controls and patients receiving dual antiplatelet therapy 3 h after protamine. CONCLUSION: Whole blood and classical LTA performed with all commonly used agonists enable detection of CPB-induced changes in platelet aggregation in patients not taking antiplatelet medication, whereas in patients receiving antiplatelet therapy, ADP-induced antiplatelet assays are preferable for detecting CPB-induced impairment of platelet aggregation.

Microcirculatory parameters after isotonic and hypertonic colloidal fluid resuscitation in acute hemorrhagic shock.

BACKGROUND: Volume resuscitation is one of the primary therapeutic goals in hemorrhagic shock, but data on microcirculatory effects of different colloidal fluid resuscitation regimen are sparse. We investigated sublingual mucosal microcirculatory parameters during hemorrhage and after fluid resuscitation with gelatin, hydroxyethyl starch, or hypertonic saline and hydroxyethyl starch in pigs. METHODS: To induce hemorrhagic shock, 60% of calculated blood volume was withdrawn. Microvascular blood flow was assessed by laser Doppler velocimetry. Microcirculatory hemoglobin oxygen saturation was measured with a tissue reflectance spectrophotometry, and side darkfield imaging was used to visualize the microcirculation and to quantify the flow quality. Systemic hemodynamic variables, systemic acid base and blood gas variables, and lactate measurements were recorded. Measurements were performed at baseline, after hemorrhage, and after fluid resuscitation with a fixed volume regimen. RESULTS: Systemic hemodynamic parameters returned or even exceeded to baseline values in all three groups after fluid resuscitation, but showed significantly higher filling pressures and cardiac output values in animals treated with isotonic colloids. Microcirculatory parameters determined in gelatin and hydroxyethyl starch resuscitated animals, and almost all parameters except microvascular hemoglobin oxygen saturation in animals treated with hypertonic saline and hydroxyethyl starch, were restored after treatment. DISCUSSION: Hemorrhaged pigs can be hemodynamically stabilized with either isotonic or hypertonic colloidal fluids. The main finding is an adequate restoration of sublingual microcirculatory blood flow and flow quality in all three study groups, but only gelatin and hydroxyethyl starch improved microvascular hemoglobin oxygen saturation, indicating some inadequate oxygen supply/demand ratio maybe due to a better restoration of systemic hemodynamics in isotonic colloidal resuscitated animals.

Fibrinogen in craniosynostosis surgery.

BACKGROUND: During craniosynostosis repair, massive blood loss, consumption and dilution of clotting factors often result in coagulopathy, for which cryoprecipitate, fresh frozen plasma (FFP), and platelets are recommended for treatment. However, cryoprecipitate is not available in most European countries, and the efficacy of FFP in correcting fibrinogen deficiency is limited. We report our experience with human fibrinogen concentrate (Hemocomplettan) used to improve impaired fibrinogen polymerization in children. METHODS: Results of routine coagulation tests, thrombelastometry (ROTEM), transfusion requirements, administration of fibrinogen concentrate, and data on the postoperative course of nine consecutive children undergoing major craniofacial surgery were retrospectively collected from anesthesia protocols, medical charts, laboratory and ROTEM databases. RESULTS: The nine children aged 12 (8, 22) mo (median [25th, 75th percentile]), weighing 9.5 (9, 10) kg had a calculated blood loss of 80 (49, 92)% of calculated blood volume during the surgery lasting 6.4 (4.5, 7.2) h. Impaired fibrinogen polymerization detected by ROTEM was the main problem underlying dilutional coagulopathy. In all cases, sufficient hemostasis was achieved without adverse effects by administering (if necessary), repeated doses of fibrinogen concentrates (each single dose 30 mg/kg) without FFP or platelet transfusions. All children were successfully weaned from mechanical ventilation within a few hours and were able to be discharged early from the Intensive Care Unit. CONCLUSIONS: Administration of fibrinogen concentrate effectively improves fibrinogen polymerization and total clot strength, which were the main underlying problems of dilutional coagulopathy in children undergoing craniosynostosis surgery.