Multicenter Evaluation of the Quantra QPlus System in Adult Patients Undergoing Major Surgical Procedures.

BACKGROUND: The management of perioperative bleeding and the optimization of the available therapies are subjects of significant clinical interest. Clinical guidelines recommend the use of whole blood viscoelastic testing devices to target the utilization of blood products during major surgical procedures. The Quantra QPlus System is a new cartridge-based viscoelastic testing device based on an innovative ultrasound technology. The aim of this study was to evaluate this new system in a surgical population. METHODS: Two hundred seventy-seven adult subjects were enrolled in a multicenter, prospective observational study consisting primarily of patients undergoing cardiac and major orthopedic surgeries. Samples were obtained at multiple time points for testing on the Quantra QPlus System, the rotational thromboelastometry (ROTEM) delta, and standard coagulation tests. Quantra measurements included Clot Time (CT), Heparinase Clot Time (CTH), Clot Time Ratio (CTR), Clot Stiffness (CS), Fibrinogen (FCS), and Platelet (PCS) Contributions to CS. Data analyses included assessment of the concordance of Quantra parameters with a series of clinical composite indexes formed on the basis of standard coagulation tests in 3 domains representing increased, decreased, and normal/subclinical coagulation function. Linear regression and receiver operator characteristic (ROC) analyses of Quantra parameters with corresponding parameters from ROTEM assays were also performed. RESULTS: The accuracy (overall percent agreement or ratio of true positives and true negatives over the entire population) between the Quantra and the composite indexes was between 72% and 98% depending on the specific parameter. Linear regression analysis indicated that the correlation between ROTEM delta and Quantra was very strong with r values ranging between 0.84 and 0.89. Results from ROC analysis demonstrated sensitivities and specificities in the 80%-90% range when QPlus parameters were used to discriminate ROTEM threshold values currently used in goal-directed treatment algorithms. CONCLUSIONS: This study demonstrated that the Quantra QPlus System is strongly correlated with a well-established viscoelastic testing device and its parameters effectively represent the results from multiple standard laboratory assays. The Quantra has been designed to operate at the point of care with the potential to provide rapid and comprehensive results to aid in the management of coagulopathic patients.

Comparison of Coagulation Parameters in Arterial and Venous Blood in Cardiac Surgery Measured Using the Quantra System.

OBJECTIVE: Perioperative coagulation testing often is performed with arterial samples even though device reference ranges typically are established in venous samples. Although limited studies exist comparing coagulation parameters across sampling sites, viscoelastic testing devices have demonstrated some differences. The objective of this study was to compare coagulation parameters determined using the Quantra System for venous and arterial samples. DESIGN: Prospective, observational study. SETTING: Tertiary care university hospital. PARTICIPANTS: The study comprised 30 adult patients undergoing cardiac surgery. INTERVENTIONS: Paired arterial and venous samples were obtained at 2 of the following time points: baseline, during bypass, or after protamine reversal of heparin. Quantra measurements included Clot Time (CT), Heparinase Clot Time (CTH), Clot Time Ratio (CTR), Clot Stiffness (CS), and Fibrinogen (FCS) and Platelet (PCS) Contributions to clot stiffness. MEASUREMENTS AND MAIN RESULTS: The relationship and agreement between matched data pairs were established and statistical analysis was performed via paired t tests. CTR, CS, FCS, and PCS were unaffected by the sampling site, whereas CT and CTH demonstrated statistically significant differences between arterial and venous samples (p < 0.001). Arterial clot times were prolonged relative to the venous ones with a mean percent error of 14.2 % and 11.9 %, respectively. These results are in general agreement with those reported for other viscoelastic testing devices. CONCLUSIONS: This study demonstrates that Quantra clot stiffness-based parameters (CS, FCS, PCS) are unaffected by sampling site, whereas the clot time parameters (CT and CTH) show good correlation in the presence of a bias. CTR, a ratio of CT and CTH, also is unaffected.

Delayed Anaphylaxis to Mammalian Meat Following Tick Exposure and Its Impact on Anesthetic Management for Cardiac Surgery: A Case Report.

Hypersensitivity reactions to mammalian meat following tick exposure are increasing in prevalence and provide a unique challenge to anesthesiologists. The reactions, including anaphylaxis, are delayed and therefore may not be easily recognized and treated. The risk is especially high in cardiac surgery, where several potential triggers, including biological valves as well as heparin, are used frequently. In the presence of such hypersensitivity, prophylactic measures including preoperative testing and pharmacologic prophylaxis may be useful in modulating the immune response such that triggering agents may be used relatively safely. We present 3 patients with previous sensitization to meat protein following a tick bite with known allergic reactions to mammalian meat who presented for cardiac surgery involving exposure to potential allergens and discuss the perioperative management including possible prevention.

Comparison of SEER Sonorheometry With Rotational Thromboelastometry and Laboratory Parameters in Cardiac Surgery.

BACKGROUND: The Quantra Hemostasis Analyzer is a novel diagnostic device that uses an ultrasound-based technology, sonic estimation of elasticity via resonance (SEER) sonorheometry, to characterize the dynamic changes in viscoelastic properties of a blood sample during coagulation. Cardiac surgery utilizing cardiopulmonary bypass (CPB) is associated with a significant impact on the coagulation system and can result in perioperative coagulopathy. The aim of this study was to correlate SEER sonorheometry results to corresponding rotational thromboelastometry (ROTEM) and laboratory parameters obtained before, during, and after CPB. METHODS: The Quantra uses a multiwell cartridge that performs 4 independent measurements with different combination of reagents. The output test results include Clot Time, Clot Stiffness, Fibrinogen and Platelet Contribution, Clot Time Ratio, and Heparinase Clot Time. Clot Time was compared with ROTEM INTEM clotting time and the adjusted partial thromboplastin time. Clot Stiffness was compared with ROTEM EXTEM. The Fibrinogen Contribution to the Clot Stiffness was correlated to ROTEM FIBTEM as well as fibrinogen concentration by the Clauss method. The Platelet Contribution to Clot Stiffness was compared with absolute platelet count and ROTEM-determined clot elasticity attributable to platelets. RESULTS: Fifty-five patients undergoing elective cardiac surgery were enrolled in this prospective observational study. Clot Time exhibited good correlation with ROTEM INTEM clotting time (pre-CPB r = 0.84, post-CPB r = 0.65) and adjusted partial thromboplastin time (pre-CPB r = 0.72, post-CPB r = 0.89); however, the majority of values were within a narrow normal range. Clot Stiffness exhibited significant correlation with ROTEM EXTEM A10 throughout the course of the study in all samples (r = 0.84). Fibrinogen Contribution correlated strongly with FIBTEM A10 (r = 0.85), and moderately with the fibrinogen concentration (r = 0.73) determined with the Clauss assay. The Platelet Contribution to Clot Stiffness showed moderate correlation to absolute platelet counts (r = 0.48). However, the correlation between Platelet Contribution and ROTEM-determined clot elasticity attributable to platelets was stronger (r = 0.78) than platelet number. All of the correlation coefficients were statistically significant with P < .001. CONCLUSIONS: SEER sonorheometry demonstrates significant correlation with ROTEM for determining Clot Stiffness and assessing Fibrinogen Contribution. SEER sonorheometry results can provide valuable information about the coagulation status in patients undergoing cardiac surgery using CPB.

Pulmonary complications of cardiopulmonary bypass.

Pulmonary complications after the use of extracorporeal circulation are common, and they range from transient hypoxemia with altered gas exchange to acute respiratory distress syndrome (ARDS), with variable severity. Similar to other end-organ dysfunction after cardiac surgery with extracorporeal circulation, pulmonary complications are attributed to the inflammatory response, ischemia-reperfusion injury, and reactive oxygen species liberated as a result of cardiopulmonary bypass. Several factors common in cardiac surgery with extracorporeal circulation may worsen the risk of pulmonary complications including atelectasis, transfusion requirement, older age, heart failure, emergency surgery, and prolonged duration of bypass. There is no magic bullet to prevent or treat pulmonary complications, but supportive care with protective ventilation is important. Targets for the prevention of pulmonary complications include mechanical, surgical, and anesthetic interventions that aim to reduce the contact activation, systemic inflammatory response, leukocyte sequestration, and hemodilution associated with extracorporeal circulation.

Evaluation of prenatal hydronephrosis: novel criteria for predicting vesicoureteral reflux on ultrasonography.

PURPOSE: Radiographic evaluation for prenatal hydronephrosis often includes voiding cystourethrography to ascertain whether vesicoureteral reflux is present. We sought to determine whether use of voiding cystourethrography could be limited to those patients at greatest risk for vesicoureteral reflux. We hypothesized that vesicoureteral reflux could be predicted by findings on renal/bladder ultrasonography of hydroureter, renal dysmorphia and/or duplication. MATERIALS AND METHODS: We reviewed the records of patients with prenatal hydronephrosis who underwent initial postnatal ultrasonography and voiding cystourethrography during a 3-year period. The presence of vesicoureteral reflux on voiding cystourethrogram was correlated to ultrasound findings, including hydronephrosis grade, presence of hydroureter, renal dysmorphia or duplication, with ultrasound considered positive for any of the latter 3 findings. RESULTS: Of 262 patients 47 (18%) had vesicoureteral reflux. Ultrasound was positive in 24 of 29 patients (83%) with high grade reflux and 12 of 18 (67%) with low grade reflux. If ultrasonography showed any of the 3 positive findings, the odds ratio of detecting vesicoureteral reflux was 8.07 (95% CI 3.86, 16.87). Using these criteria, among all cases of prenatal hydronephrosis 5 (2%) with high grade vesicoureteral reflux and 6 (2%) with low grade reflux would have been missed. Among the 47 cases of reflux overall 5 of 29 high grade (17%) and 6 of 18 low grade cases (33%) would have been missed. CONCLUSIONS: By using ultrasonography criteria of hydroureter, duplication and renal dysmorphia for patients with prenatal hydronephrosis, vesicoureteral reflux can be detected more specifically. Using our criteria, 165 of 262 voiding cystourethrograms (63%) could have been avoided in patients with prenatal hydronephrosis during a 3-year period. Reducing these evaluations may decrease risks regarding radiation exposure, family anxiety and health care costs.

Repeated neurological complications during dialysis - a case for echo?

A 65-year old woman presented with acute or chronic renal failure and signs of right heart failure. Renal replacement therapy­using a surgically placed dialysis catheter via the left jugular vein­was repeatedly complicated by altered flows of the dialysis unit, impaired consciousness, new onset of seizures and left-sided hemiparesis. The tip of the dialysis catheter was detected on transesophageal echocardiography within the lumen of the ascending aorta. Further imaging of the neck vessels demonstrated a primary placement of the catheter in the left common carotid artery. This incident underscores the value of ultrasound guidance for placement of intravascular catheters.

Effects of early inhaled epoprostenol therapy on pulmonary artery pressure and blood loss during LVAD placement.

OBJECTIVE: Several strategies have been used to reduce the incidence of right ventricular failure after left ventricular assist device (LVAD) placement, including pulmonary vasodilation. The inhaled prostacyclin, epoprostenol, selectively dilates the pulmonary vasculature of ventilated areas of the lung, but also has been shown to inhibit platelet aggregation.(1) The authors evaluated the impact of early initiation of epoprostenol administration during LVAD placement on pulmonary artery pressures, use of vasoactive drugs, and blood loss. DESIGN: Retrospective data review. SETTING: Single center, university hospital. PARTICIPANTS: A total of 37 consecutive patients undergoing LVAD (HeartMate II) placement were included. INTERVENTIONS: In the first group of 23 patients (group 1), inhaled epoprostenol was not initiated until weaning from cardiopulmonary bypass (CPB). In a subsequent group of 14 patients (group 2), inhaled epoprostenol was started shortly after induction of anesthesia and continued throughout and post-CPB. MEASUREMENTS: Mean and systolic pulmonary artery pressures (mPAP, sPAP), vasoactive drugs, as well as hemodynamic parameters, blood loss, and use of blood products were recorded at the following time points: Baseline (BL), pre-CPB, post-CPB, and during postoperative days (POD) 0, 1, and 2. Data are presented as mean±SD or median [25%, 75%]. RESULTS: Groups did not differ in demographic characteristics and comorbidities. BL sPAP (41±13 v 46±15 mmHg; p = 0.051) and mPAP (32±8 v 34±8 mmHg; p = 0.483) values were not different between the groups. Systolic and mPAP in group 1 were significantly lower in the postoperative period compared with BL (sPAP on POD 0: 34±6 mmHg; p<0.001; mPAP on POD 0, 1, and 2: 24±4 mmHg, 25±4 mmHg, 27±6 mmHg; p<0.001-0.003)). In contrast, in group 2, sPAP as well as mPAP were significantly lower during weaning from CPB (sPAP: 37±8; p = 0.002; mPAP: 28±5 mmHg; p = 0.016) as well as in the postoperative period (sPAP on POD 0, 1 and 2: 34±7, 35±7, and 37±10 mmHg; p<0.001-0.004; mPAP on POD 0, 1, and 2: 24±4 mmHg, 25±5 mmHg, 27±6 mmHg; p<0.001-0.006). Blood loss on postoperative day 0 was significantly lower in group 1 (1646 mL [1137, 2300] v 2915 mL [2335, 6155]; p = 0.006). Epoprostenol was a significant predictor of blood loss in the regression model (p<0.001) but did not predict a change in sPAP. CONCLUSIONS: Inhaled prostacyclin reduces sPAP and mPAP in the postoperative period after LVAD placement regardless of the timing of initiation. Early initiation seems to reduce sPAP as well as mPAP more effectively during the weaning process from CPB. However, early initiation is associated with an increased blood loss in the immediate postoperative period. The concept of preventively "bathing" the lung in prostacyclin should be evaluated critically in a prospective fashion to adequately examine this question.

Local anesthetic-induced inhibition of human neutrophil priming: the influence of structure, lipophilicity, and charge.

BACKGROUND AND OBJECTIVES: Local anesthetics (LAs) are widely known for inhibition of voltage-gated sodium channels underlying their antiarrhythmic and antinociceptive effects. However, LAs have significant immunomodulatory properties and were shown to affect human neutrophil functions independent of sodium-channel blockade. Previous studies suggest a highly selective interaction between LAs and the α-subunit of G protein-coupled receptors of the Gq/G11 family as underlying mechanism. Providing a detailed structure function analysis, this study aimed to determine the active parts within the LA molecule responsible for the effects on human neutrophil priming. METHODS: Human neutrophils were incubated with structurally different LAs for 60 minutes, followed by priming and activation using either platelet-activating factor or lysophosphatidic acid and N-formyl-methionyl-L-leucyl-L-phenylalanine. Superoxide anion generation was determined, using the cytochrome c reduction assay. RESULTS: Differences in priming inhibition of human neutrophils between LAs were smaller than expected, although significant. Ester-linked LAs blocked priming responses more effectively than did amide LAs. Furthermore, the inhibitory potency of LAs on priming decreased with an increase of their respective octanol-buffer coefficient, and inhibition did not correlate with sodium-channel-blocking potency. Charge was not crucially required for priming inhibition, yet it played a role in effect size. CONCLUSIONS: Local anesthetics significantly attenuated Gαq-protein-mediated neutrophil priming. The most potent inhibition was achieved by ester compounds, inversely correlated with their octanol-buffer coefficient, and enhanced by permanent charges within the LA molecule. No correlation to their potency of blocking sodium channels was found.

Systemic lidocaine decreases the Bispectral Index in the presence of midazolam, but not its absence.

STUDY OBJECTIVE: To evaluate the effects of intravenous (IV) lidocaine on the Bispectral Index (BIS) in the presence or absence of midazolam. DESIGN: Prospective, randomized, double-blinded, placebo-controlled clinical study. SETTING: Operating room of a university hospital. PATIENTS: 96 ASA physical status 1, 2, and 3 patients undergoing general anesthesia. INTERVENTIONS: Patients were assigned to one of 6 treatment groups to receive IV midazolam (0.03 mg/kg) or placebo, followed 5 minutes later by one of three IV preinduction doses of lidocaine: 0.5, 1.0, or 1.5 mg/kg. MEASUREMENTS: BIS values were recorded before administration of lidocaine and at 30-second intervals afterwards for three minutes. The primary endpoint was the average BIS level recorded. MAIN RESULTS: Baseline BIS values were lower in the midazolam group (94 ± 4 vs. 90 ± 7, P < 0.001). There was no significant decrease in BIS values in the placebo group for any of the three lidocaine doses. However, in the midazolam groups, significant decreases in BIS levels versus baseline values were measured. CONCLUSION: IV lidocaine decreases BIS in the presence of midazolam, suggesting that the effect of lidocaine on BIS is not direct, but rather results from modulation by midazolam.

The effect of the intrathoracic pressure regulator on hemodynamics and cardiac output.

The intrathoracic pressure regulator (ITPR) (CirQLator; Advanced Circulatory Systems Inc, Roseville, Minn) is a novel, noninvasive device intended to increase cardiac output and blood pressure in hypovolemic or cardiogenic shock by generating a continuous low-level intrathoracic vacuum in between positive pressure ventilations. Although there are robust data supporting the benefit of the ITPR in multiple animal models of shock, the device has not been used in humans.The goals of this study were to evaluate both the safety and efficacy of the ITPR in humans. Twenty patients undergoing coronary artery bypass graft surgery were enrolled in this phase 1 study. Intraoperative use of both pulmonary artery pressure monitoring and transesophageal echocardiography (TEE) was required for study inclusion. Hemodynamic variables as well as TEE measurements of left ventricular performance were collected at baseline and after the ITPR device was activated, before surgical incision. Thermodilution cardiac output increased significantly with the application of the ITPR (4.9 vs. 5.5 L/min; P = 0.017). Similarly, cardiac output was measured by TEE (5.1 vs. 5.7 L/min; P = 0.001).There were significant increases in pulmonary artery systolic blood pressures (35 vs. 38 mmHg; P G 0.001) and mean pulmonary artery pressures (24 vs. 26 mmHg; P = 0.008). There were no significant differences in systemic blood pressures, left ventricular volumes, stroke volume, or ejection fraction as measured by TEE. Using two different measurement techniques, application of the ITPR increased cardiac output in normovolemic anesthetized patients who underwent coronary artery bypass graft before sternotomy. These data suggest that the ITPR has the potential to safely and effectively increase cardiac output in humans.

HbA1c and diabetes predict perioperative hyperglycemia and glycemic variability in on-pump coronary artery bypass graft patients.

OBJECTIVE: Perioperative hyperglycemia and glycemic variability are considered independent predictors of morbidity and mortality in critically ill patients. The purpose of this study was to investigate the relation of HbA1c and/or a prior diagnosis of diabetes mellitus and intra- and postoperative hyperglycemia and glycemic variability. DESIGN: A retrospective data analysis from a single-center database. SETTING: A single university hospital. PARTICIPANTS: Diabetic and nondiabetic patients undergoing isolated on-pump coronary artery bypass graft (CABG) surgery. MEASUREMENTS: One hundred twenty patients undergoing isolated CABG surgery were evaluated. Glucose values were acquired pre-, intra-, and postoperatively on the day of surgery as well as on the first postoperative day. The extent of hyperglycemia within and between groups was compared using mean and maximum glucose values. As a measure of the patient's individual intra- and postoperative glucose variability, the standard deviation (SD) and the coefficient of variation (CV) of glucose values were calculated. Outcomes were analyzed using a multiple logistic regression model. RESULTS: Diabetics and/or patients with elevated HbA1c had higher postoperative glucose levels, a higher SD, and a higher CV of postoperative glucose values; however, higher glucose variability was not associated with higher rates of complication. Intraoperative glucose values and variation did not differ significantly between groups. Increased mean blood glucose values were associated with increased risk of infection. CONCLUSIONS: Diabetic status and/or elevated HbA1c are predictors of postoperative glucose variability and hyperglycemia in CABG surgery patients. However, in the intraoperative period, these groups show similar glycemic responses to operative stress.

Local anesthetic effects on human neutrophil priming and activation.

BACKGROUND: The anti-inflammatory effects of local anesthetics (LAs) are well documented. Local anesthetics in micromolar concentrations inhibit extracellular oxygen release in isolated neutrophils; the underlying mechanism seems to be an inhibition of leukocyte priming. It remains unclear, however, if first, these effects also can be observed in whole blood, and second, if the priming of other neutrophil functions is similarly attenuated by LAs. Furthermore, the effects of LAs on intracellular generation of oxidative species remain to be investigated. METHODS: Whole-blood samples from healthy volunteers were incubated for 0, 1, or 3 hrs with different concentrations (10 to 10 M) of either lidocaine, ropivacaine, QX314, or NaCl 0.9% as control. Dihydroethidium was added to quantify oxidative burst. Samples were primed with platelet-activating factor (PAF, 10 M) and/or activated with formyl-methyl-leucyl-phenylalanine (10 M) for 15 mins each. After staining for CD11b and lysis of erythrocytes, samples were analyzed by flow cytometry. RESULTS: Priming of leukocytes is a relevant mechanism in whole blood. Platelet-activating factor stimulates the priming of oxidative burst and CD11b expression. Lidocaine up to millimolar concentrations did not affect the PAF priming and formyl-methyl-leucyl-phenylalanine activation of oxidative burst. The priming of CD11b expression and the priming and activation of changes in cell morphology were significantly attenuated by lidocaine. CONCLUSIONS: The intracellular generation of reactive oxygen species remains largely unaffected by LAs in clinical concentrations. This suggests that the anti-inflammatory effects of LAs do not interfere with the host defense.