Reliability of Passive Leg Raising, Stroke Volume Variation and Pulse Pressure Variation to Predict Fluid Responsiveness During Weaning From Mechanical Ventilation After Cardiac Surgery: A Prospective, Observational Study.

OBJECTIVE: During assisted ventilation and spontaneous breathing, functional haemodynamic parameters, including stroke volume variation (SVV) and pulse pressure variation (PPV), are of limited value to predict fluid responsiveness, and the passive leg raising (PLR) manoeuvre has been advocated as a surrogate method. We aimed to study the predictive value of SVV, PPV and PLR for fluid responsiveness during weaning from mechanical ventilation after cardiac surgery. METHODS: Haemodynamic variables and fluid responsiveness were assessed in 34 patients. Upon arrival at the intensive care unit, measurements were performed during continuous mandatory ventilation (CMV) and spontaneous breathing with pressure support (PSV) and after extubation (SPONT). The prediction of a positive fluid responsiveness (defined as stroke volume increase >15% after fluid administration) was tested by calculating the specific receiver operating characteristic (ROC) curves. RESULTS: A significant increase in stroke volumes was observed during CMV, PSV and SPONT after fluid administration. There were 19 fluid responders (55.9%) during CMV, with 22 (64.7%) and 13 (40.6%) during PSV and SPONT, respectively. The predictive value for a positive fluid responsiveness (area under the ROC curve) for SVV was 0.88, 0.70 and 0.56; was 0.83, 0.69 and 0.48 for PPV; was 0.72, 0.74 and 0.70 for PLR during CMV, PSV and SPONT, respectively. CONCLUSION: During mechanical ventilation, adequate prediction of fluid responsiveness using SVV and PPV was observed. However, during spontaneous breathing, the reliability of SVV and PPV was poor. In this period, PLR as a surrogate was able to predict fluid responsiveness better than SVV or PPV but was less reliable than previously reported.

Accuracy, Precision, and Trending of 4 Pulse Wave Analysis Techniques in the Postoperative Period.

OBJECTIVE: The aim of this study was to analyze the accuracy, precision, and trending ability of the following 4 pulse wave analysis devices to measure continuous cardiac output: PiCCO2 ([PCCO]; Pulsion Medical System, Munich, Germany); LiDCORapid ([LCCO]; LiDCO Ltd, London, UK); FloTrac/Vigileo ([FCCO]; Edwards Lifesciences, Irvine, CA); and Nexfin ([NCCO]; BMEYE, Amsterdam, The Netherlands). DESIGN: Prospective, observational clinical study. SETTING: Intensive care unit of a single-center, teaching hospital. PARTICIPANTS: The study comprised 22 adult patients after elective coronary artery bypass surgery. INTERVENTIONS: Three measurement cycles were performed in all patient durings their immediate postoperative intensive care stay before and after fluid loading. Hemodynamic measurements were performed 5 minutes before and immediately after the administration of 500 mL colloidal fluid over 20 minutes. MEASUREMENTS AND MAIN RESULTS: PCCO, LCCO, FCCO, and NCCO were assessed and compared with cardiac output derived from intermittent transpulmonary thermodilution (ICO). One hundred thirty-two matched sets of data were available for analysis. Bland-Altman analysis using linear mixed effects models with random effects for patient and trial revealed a mean bias ±2 standard deviation (%error) of -0.86 ± 1.41 L/min (34.9%) for PCCO-ICO, -0.26 ± 2.81 L/min (46.3%) for LCCO-ICO, -0.28 ± 2.39 L/min (43.7%) for FCCO-ICO, and -0.93 ± 2.25 L/min (34.6%) for NCCO-ICO. Bland-Altman plots without adjustment for repeated measurements and replicates yielded considerably larger limits of agreement. Trend analysis for all techniques did not meet criteria for acceptable performance. CONCLUSIONS: All 4 tested devices using pulse wave analysis for measuring cardiac output failed to meet current criteria for meaningful and adequate accuracy, precision, and trending ability in cardiac output monitoring.

Impact of city police layperson education and equipment with automatic external defibrillators on patient outcome after out of hospital cardiac arrest.

INTRODUCTION: Out of hospital cardiac arrest (OHCA) occurs frequently and the outcome is often dismal. Early defibrillation saves lives and brain function in OHCA. The Zurich city police (STAPO) forces were instructed and equipped to provide basic life support (BLS) and to use an AED in 2009. METHODS: Retrospective observational study comparing period 1 (P1) 2004-2009 before equipping and training of the STAPO and period 2 (P2) 2010-2015 after the implementation. Patients suffering from OHCA of cardiac or presumed cardiac origin in the city of Zurich undergoing CPR by EMS in P1 (n=709) and P2 (n=684) were included. Intervention periods and outcome were compared between the periods. Outcome variables were adjusted for patient age and gender, witnessed status, and defibrillation by the EMS, STAPO, layperson or no defibrillation. RESULTS: In P2, CPR was started by the STAPO in a median of 8 (IQR 6-9) minutes after the arrest and thus significantly earlier (median 3min) than by the EMS (p<0.001). STAPO performed the first defibrillation in a median of 9 (IQR 8-10) minutes and thus significantly earlier (median 6min) than the EMS (p<0.001). Outcome improved significantly in P2: proportion of patients with return of spontaneous circulation (ROSC, P2 35.8%, P1 24.0%, OR 1.8, 95% CI 1.4-2.2, p<0.001), hospital admission (P2 32.2%, P1 21.4%, OR 1.7, 95% CI 1.4-2.2, p<0.001) and survival to hospital discharge (P2 13.6%, P1 6.9%, OR 2.1 95% CI 1.5-3.0, p<0.001). If the patient was firstly defibrillated by the STAPO, ROSC (STAPO 74.4%, adj. OR 2.6, 95% CI 1.3-5.4, p=0.010) and hospital admission (STAPO 72.1%, adj. OR 2.8, 95% CI 1.4-5.6, p=0.005) was higher compared to patients firstly defibrillated by the EMS. Survival to hospital discharge (STAPO 30.2%, adj. OR 1.4, 95% CI 0.7-2.9, p=0.38) was unchanged. CONCLUSION: Dispatching BLS trained and AED equipped police forces results in earlier and more successful resuscitation of OHCA victims, leading to higher proportions of patients with ROSC, hospital admission and survival to hospital discharge.

Extracorporeal Membrane Oxygenation for Treatment of Acute Inverted Takotsubo-Like Cardiomyopathy From Hemorrhagic Pheochromocytoma in Late Pregnancy.

We describe the first case of a pregnant woman presenting with an acute inverted takotsubo-like cardiomyopathy caused by a postpartum diagnosed hemorrhagic pheochromocytoma, successfully treated with percutaneous venoarterial extracorporeal membrane oxygenation (va-ECMO). During admission, an emergency cesarean delivery had to be performed. The fetus needed resuscitation for 5 minutes. The mother was successfully resuscitated and treated with percutaneous va-ECMO for 7 days. Despite advances in diagnostic techniques during the past decade, in many cases, pheochromocytoma in pregnancy is still missed. This results in a maternal and fetal mortality rate of up to 30% in both.

The length of stay in the post-anaesthesia care unit correlates with pain intensity, nausea and vomiting on arrival.

BACKGROUND: The benefit of the post-anaesthesia care unit (PACU) with respect to an early detection of postoperative complications is beyond dispute. From a patient perspective, prevention and optimal management of pain, nausea and vomiting (PONV) are also of utmost importance. The aims of the study were therefore to prospectively measure pain and PONV on arrival to the PACU and before discharge and to determine the relationship of pain and PONV to the length of stay in the PACU. METHODS: Postoperative pain was assessed over 30 months using a numeric rating scale on admittance to the PACU and before discharge; in addition, PONV was recorded. Statistical analysis was done considering gender, age, American Society of Anesthesiologists (ASA) classification, surgical speciality, anaesthesia technique, duration of anaesthesia, intensity of nursing and length of stay. RESULTS: Data of 12,179 patients were available for analysis. The average length of stay in the PACU was 5.7 ± 5.9 h, whereas regular PACU patients stayed for 3.2 ± 1.9 h and more complex IMC patients stayed for 15.1 ± 6.0 h. On admittance, 27% of patients were in pain and the number decreased to 13% before discharge; 3% experienced PONV. Risk factors for increased pain determined by multivariate analysis were female gender; higher ASA classification; general, cardiac and orthopaedic surgery and prolonged case duration. In more complex IMC patients, pain scores were higher on arrival but dropped to similar levels before discharge compared to regular PACU patients. Female gender and postoperative pain were risk factors for postoperative vomiting. Pain and PONV on arrival correlated with length of stay in the PACU. Pain- or PONV-free patients stayed almost half of the time in the PACU compared to patients with severe pain or vomiting on arrival. CONCLUSIONS: The majority of PACU patients had good pain control, both on admittance and before discharge, and the overall incidence of PONV was low. Managing patients in the PACU could achieve a significant reduction of pain and PONV. The level of pain and presence of PONV on admittance to the PACU correlate with and act as predictors for increased length of PACU stay.

[New aspects of minimally invasive cardiac output monitoring]. / Hämodynamisches Monitoring - Neue Aspekte des minimalinvasiven Herzzeitvolumen-Monitorings.

The variety of minimally invasive cardiac output (CO) monitoring devices is growing rendering it difficult to keep track of new developments. In this article technical principles, limitations and validation procedures considering new aspects are reviewed. An integrated approach for their use is proposed since no single device can comply with all clinical needs. CO should be interpreted in combination with clinical information and other hemodynamic parameters. It's evident that not the monitor per se, but only the protocol / therapy based on the hemodynamic data can improve patients outcome.

Discrimination of healthy and glaucomatous eyes based on the ocular pulse amplitude: a diagnostic case-control study.

By measuring the ocular pulse amplitude (OPA), the dynamic contour tonometer (DCT) assesses intraocular pressure (IOP). Hypothesizing that OPA is characteristic for the IOP when considered with the systemic arterial blood pressure, we assumed the ratio of ocular and arterial pulsation amplitudes is larger in glaucoma patients. Bi-ocular DCT-OPA assessment was synchronized with arterial pulsations using Finapres® technology, thereby enabling blood pressure determination for each corresponding IOP value every 0.01 s for 12 s. Based on measurements and calculations in 10 healthy subjects and 11 glaucoma patients, we conclude that the ratio of the OPA and blood pressure variances is a strong glaucoma diagnostic indicator, thereby justifying further investigation.

Perioperative assessment of platelet function in patients under antiplatelet therapy.

Platelets play a central role in primary hemostasis. Analysis of platelet function is therefore a cornerstone in the global assessment of the coagulation status in the perioperative setting, primarily in patients receiving antiplatelet medication, such as cyclooxygenase-1 inhibitors, adenosine diphosphate antagonists and glycoprotein IIb/IIIa inhibitors. In these patients, knowledge of residual platelet function is highly warranted in order to maintain an optimal and individual balance perioperatively between platelet function and inhibition - that is, bleeding and thrombosis. Traditional laboratory-based assays, such as light-transmission aggregometry and flow cytometry, are the clinical standards of platelet function testing today. Light-transmission aggregometry is one of the most widely used tests to identify and diagnose defects in platelet function. The majority of the conventional laboratory-based techniques are labor intensive, costly and time consuming, and require a high degree of experience and expertise to perform and interpret. Therefore, new automated technologies have been developed to measure platelet function more rapidly and easily, and several techniques can be used at the bedside, including whole blood aggregometry, high shear-induced platelet function assessment or viscoelastic measurement techniques. All methods assessing platelet function are summarized and their limitations are discussed in this article, emphasizing their perioperative use.

Inflammatory response in ventilated left and collapsed right lungs, serum and pleural fluid, in transthoracic esophagectomy for cancer.

INTRODUCTION: Open, right-sided, transthoracic esophagectomy with one-lung ventilation (OLV) triggers a massive inflammatory reaction. The influence of the OLV on the inflammatory cascade is unclear. Data on the inflammatory response in the ventilated left and collapsed right lung, respectively, are scarce. The aim of this study was to analyze this reaction in bronchoalveolar lavage (BAL) fluid from both lungs, the right pleural space and the peripheral blood, and to study its time course. METHODS: Concentrations of interleukin (IL)-6, IL-8, IL-10 and IL-1RA in the BAL fluids from the right and left lungs, respectively, in the peripheral blood and in the right pleural space in patients undergoing transthoracic esophagectomy for cancer, were determined using enzyme-linked immunosorbent assays in 29 patients. RESULTS: Assay of the pro-inflammatory cytokines in the bilateral BAL fluids showed significantly higher concentrations in the ventilated left lung at the time of extubation. The anti-inflammatory response was only seen with respect to IL-1RA, but not IL-10, and was mostly restricted to the ventilated left lung. In the blood, only IL-6, IL-10 and IL-1RA increased, whereas IL-8 showed little change. The response was already observed at the end of surgery, indicating a rapid reaction to the surgical and anesthetic trauma. In the pleural fluid, all cytokine concentrations increased, and the highest values were detected on day one post-surgery, and decreased thereafter. Pulmonary complications or anastomotic leakage were not related to the cytokine concentrations. CONCLUSION: Both the ventilated left and the collapsed right lung showed an inflammatory response. The response was more pronounced on the ventilated left side and the time courses were significantly different. In the blood, the pro-inflammatory IL-6 and both anti-inflammatory cytokines increased early on. All cytokines increased in the pleural cavity. The findings underline the complexity of the inflammatory reaction associated with OLV in transthoracic esophagectomy.

Uncalibrated radial and femoral arterial pressure waveform analysis for continuous cardiac output measurement: an evaluation in cardiac surgery patients.

OBJECTIVES: Arterial pressure waveform analysis is a less invasive alternative to the pulmonary artery catheter for continuous cardiac output (CO) measurement. Uncalibrated and calibrated systems are actually available (ie, the FloTrac/Vigileo system [Edwards Lifesciences, Irvine, CA] and the PiCCOplus system [Pulsion Medical Systems, Munich, Germany]). According to the FloTrac/Vigileo manufacturer, reliable measurements can be performed using any existing arterial catheter. The aim of this study was to evaluate CO determined by the FloTrac/Vigileo system using a radial (FCO(radial)) and femoral arterial catheter (FCO(femoral)) as well as the PiCCOplus system (PCO). Intermittent pulmonary artery thermodilution (ICO) was used as primary reference technique. DESIGN: A prospective clinical study. SETTING: A teaching hospital, single center. PARTICIPANTS: Twenty-six cardiac surgery patients. INTERVENTIONS: Perioperative CO measurements. MEASUREMENTS AND MAIN RESULTS: CO was assessed at predefined measurement points. FCO(radial), FCO(femoral), and PCO were recorded after the induction of anesthesia, after sternotomy, at skin closure, after intensive care unit transfer, and during intensive care unit stay 12 and 24 hours after study initiation. ICO was determined as the mean of 3 bolus injections. Bland-Altman analysis revealed comparable mean bias and limits of agreement for FCO(radial), FCO(femoral), and PCO when compared with ICO. There was a decreased agreement for all devices in the postoperative period. However, a consistently close agreement was observed for the direct comparison between FCO(radial) and FCO(femoral). CONCLUSIONS: Performance of the FloTrac/Vigileo system via radial as well as femoral access and the PiCCOplus monitoring for cardiac output measurement were comparable when tested against intermittent thermodilution in cardiac surgery patients.

Assessment of cardiac output changes using a modified FloTrac/Vigileo algorithm in cardiac surgery patients.

INTRODUCTION: The FloTrac/Vigileo (Edwards Lifesciences, Irvine, CA, USA) allows pulse pressure-derived cardiac output measurement without external calibration. Software modifications were performed in order to eliminate initially observed deficits. The aim of this study was to assess changes in cardiac output determined by the FloTrac/Vigileo system (FCO) with an initially released (FCOA) and a modified (FCOB) software version, as well as changes in cardiac output from the PiCCOplus system (PCO; Pulsion Medical Systems, Munich, Germany). Both devices were compared with cardiac output measured by intermittent thermodilution (ICO). METHODS: Cardiac output measurements were performed in patients after elective cardiac surgery. Two sets of data (A and B) were obtained using FCOA and FCOB in 50 patients. After calibration of the PiCCOplus system, triplicate FCO and PCO values were recorded and ICO was determined in the supine position and cardiac output changes due to body positioning were recorded 15 minutes later (30 degrees head-up, 30 degrees head-down, supine). Student's t test, analysis of variance and Bland-Altman analysis were calculated. RESULTS: Significant changes of FCO, PCO and ICO induced by body positioning were observed in both data sets. For set A, DeltaFCOA was significantly larger than DeltaICO induced by positioning the head down. For set B, there were no significant differences between DeltaFCOB and DeltaICO. For set A, increased limits of agreement were found for FCOA-ICO when compared with PCO-ICO. For set B, mean bias and limits of agreement were comparable for FCOB-ICO and PCO-ICO. CONCLUSIONS: The modification of the FloTrac/Vigileo system resulted in an improved performance in order to reliably assess cardiac output and track the related changes in patients after cardiac surgery.

A fulminant malignant hyperthermia episode in a patient with ryanodine receptor gene mutation p.Tyr522Ser.

A 37-yr-old patient scheduled for elective bursectomy developed fulminant malignant hyperthermia (MH) under sevoflurane anesthesia. The first sign was a dramatic increase in end-tidal CO(2). Symptomatic and specific therapy was rapidly instituted. Postoperative rhabdomyolysis was treated with veno-venous hemofiltration. The patient rejected open muscle biopsy for in vitro contracture testing. Therefore, molecular testing was performed. An infrequent MH causative mutation was identified on the ryanodine receptor gene. This case report confirms the causative nature of this mutation. It also shows that molecular genetic investigation may be as appropriate as in vitro contracture testing to confirm the diagnosis after a clinical episode of MH.

Monitoring recombinant factor VIIa treatment: efficacy depends on high levels of fibrinogen in a model of severe dilutional coagulopathy.

OBJECTIVES: Recombinant activated factor VII (rFVIIa) is increasingly being given to treat massive bleeding. However, there is no clear guidance on which patients are suitable for treatment and how the effects of treatment should be monitored. The aim of this in vitro study was to assess the coagulation status of severely hemodiluted blood samples before and after treatment with therapeutic doses of rFVIIa and/or fibrinogen with 2 viscoelastic point-of-care coagulation analyzers: ROTEM (Pentapharm GmbH, Munich, Germany) and Sonoclot (Sienco Inc, Arvada, CO). DESIGN: Laboratory study. SETTING: Research coagulation laboratory. PARTICIPANTS: Ten healthy male volunteers without hereditary or acquired coagulation disorders. INTERVENTIONS: Blood samples were obtained. After severe hemodilution with albumin 5%, therapeutic doses of rFVIIa and/or fibrinogen were added, and the coagulation status was assessed with new 1:1,000 diluted tissue factor-activated tests from ROTEM and Sonoclot. MEASUREMENTS AND MAIN RESULTS: The administration of therapeutic doses of rFVIIa to hemodiluted samples shortened the initiation phase of coagulation only. Isolated fibrinogen administration to physiologic levels improved both the initiation of coagulation as well as clot formation and strength. Combined fibrinogen and rFVIIa administration further improved both effects. CONCLUSIONS: ROTEM and Sonoclot were able to monitor the effects of rFVIIa and fibrinogen administration with 1:1,000 diluted tissue factor-activated tests. The efficacy of rFVIIa was largely dependent on the presence of high levels of fibrinogen in reversing this severe dilutional coagulopathy.

Assessment of stroke volume variation for prediction of fluid responsiveness using the modified FloTrac and PiCCOplus system.

INTRODUCTION: Stroke volume variation (SVV) has repeatedly been shown to be a reliable predictor of fluid responsiveness. Various devices allow automated clinical assessment of SVV. The aim of the present study was to compare prediction of fluid responsiveness using SVV, as determined by the FloTrac/Vigileo system and the PiCCOplus system. METHODS: In patients who had undergone elective cardiac surgery, SVVFloTrac was determined via radial FloTrac sensor, and SVVPiCCO and pulse pressure variation were assessed via a femoral PiCCO catheter. Stroke volume was assessed by transpulmonary thermodilution. All variables were recorded before and after a volume shift induced by a change in body positioning (from 30 degrees head-up position to 30 degrees head-down position). Pearson correlation, t-test, and Bland-Altman analysis were performed. Area under the curve was determined by plotting receiver operating characteristic curves for changes in stroke volume in excess of 25%. P < 0.05 was considered statistically significant. RESULTS: Body positioning resulted in a significant increase in stroke volume; SVVFloTrac and SVVPiCCO decreased significantly. Correlations of SVVFloTrac and SVVPiCCO with change in stroke volume were similar. There was no significant difference between the areas under the curve for SVVFloTrac and SVVPiCCO; the optimal threshold values given by the receiver operating characteristic curves were 9.6% for SVVFloTrac (sensitivity 91% and specificity 83%) and 12.1% for SVVPiCCO (sensitivity 87% and specificity 76%). There was a clinically acceptable agreement and strong correlation between SVVFloTrac and SVVPiCCO. CONCLUSION: SVVs assessed using the FloTrac/Vigileo and the PiCCOplus systems exhibited similar performances in terms of predicting fluid responsiveness. In comparison with SVVPiCCO, SVVFloTrac has a lower threshold value.

The accuracy of preload assessment by different transesophageal echocardiographic techniques in patients undergoing cardiac surgery.

OBJECTIVES: The aim of this study was to compare the following approaches to assess left ventricular preload by transesophageal echocardiography (TEE): left ventricular end-diastolic volume index (LVEDVI) determined by using the method of disc summation (LVEDVI(Md)) and left ventricular end-diastolic area index (LVEDAI) were compared with LVEDVI assessed by the modified Simpson formula (LVEDVI(Si)). Global end-diastolic volume index (GEDVI) and stroke volume index (SVI) measured by the PiCCO(plus) system (Pulsion Medical Systems, Munich, Germany) were used as TEE-independent reference variables. DESIGN: Prospective observational study. SETTING: Community hospital. PARTICIPANTS: Twenty-two patients undergoing elective cardiac surgery. INTERVENTIONS: After the induction of anesthesia, hemodynamic assessment by TEE and the PiCCO(plus) system was made 20 (T(1)) and 10 minutes (T(2)) before and 10 (T(3)) and 20 minutes (T(4)) after a fluid trial. At each time point, LVEDVI(Md), LVEDAI, LVEDVI(Si), GEDVI, and SVI were determined. MEASUREMENTS AND MAIN RESULTS: The fluid trial resulted in a significant increase of all preload variables measured at T(3). At T(4), all preload variables but LVEDVI(Md) showed a significant decrease. The mean bias +/- 2 SD for percent changes (Delta) of LVEDVI(Md) - DeltaLVEDVI(Si) was 1.5% +/- 59.0% and for DeltaLVEDAI - Delta LVEDVI(Si) 0.9% +/- 23.6%. The correlation between LVEDVI(Md) and LVEDVI(Si) was significantly weaker than between LVEDAI and LVEDVI(Si) (p < 0.001). Comparing TEE measurements with GEDVI and SVI, strong correlations were observed for LVEDAI and LVEDVI(Si) only. CONCLUSION: The method of disc summation cannot be recommended for preload assessment during a fluid challenge in cardiac surgery patients. By contrast, single-plane area measurements provided reliable information when compared with the application of the modified Simpson formula.

How often should we perform arterial blood gas analysis during thoracoscopic surgery?

STUDY OBJECTIVES: To continuously measure arterial blood gases (ABGs), to calculate the percentage of anticipated changes over time, and to develop recommendations for sampling frequencies of arterial blood gases in patients undergoing thoracoscopic surgery. DESIGN: Prospective, observational clinical trial. SETTING: University hospital. PATIENTS: 43 consecutive elective patients undergoing thoracoscopic surgery with one-lung ventilation. INTERVENTIONS AND MEASUREMENTS: A Paratrend 7 probe for continuous arterial partial pressure of oxygen and arterial partial pressure of carbon dioxide measurement was introduced through a radial artery cannula in the awake patient before surgery. Data were collected throughout the procedure until patients left the operating room. Afterward, time courses of arterial blood gas values were transformed into frequency space by fast Fourier transform analysis, and the expected deviations in arterial blood gases were calculated over time. MAIN RESULTS: Forty-three consecutive patients undergoing thoracoscopic surgery were included, and arterial blood gas values were measured during a total of 141.5 h. Critical arterial partial pressure of oxygen values

Kaolin-based activated coagulation time measured by sonoclot in patients undergoing cardiopulmonary bypass.

OBJECTIVES: In vivo data for the kaolin-based ACT test from the Sonoclot Analyzer (SkACT, Sienco Inc, Arvada, CO) are lacking. The aim of this study was to compare SkACT with an established kaolin-based ACT from Hemochron (HkACT) and anti-Xa activity in patients undergoing cardiopulmonary bypass (CPB). DESIGN: Prospective observational study. SETTING: Community hospital. PARTICIPANTS: Fifty patients scheduled for elective cardiac surgery. INTERVENTIONS: Blood samples were taken before CPB at baseline (T0) and after heparinization (T1 and T2), on CPB after administration of aprotinin (5, 15, 30, 60 minutes; T3-T6), and at the end after protamine infusion (T7). MEASUREMENTS AND MAIN RESULTS: A total of 375 blood samples were analyzed. ACT measurements were comparable for SkACT and HkACT at each measurement time point. Overall bias +/- standard deviation between SkACT and HkACT was -19 +/- 75 seconds (-2.4% +/- 11.7%). Mean bias between SkACT and HkACT at each time point ranged from -35 to 3 seconds (-4.5% to 2.6%) and showed no statistical significance over time. Heparin sensitivity of SkACT and HkACT, defined as (ACT(Tx)-ACT(T0))/(anti-Xa(Tx)-anti-Xa(T0)), significantly increased for measurements during CPB (p < 0.001) but without significant difference between the 2 methods. Test variability was comparable for both ACT measurement techniques. Overall test variability was 7.5% +/- 7.4% for SkACT and 7.8% +/- 11% for HkACT. CONCLUSIONS: Accuracy and performance of SkACT and HkACT were comparable for heparin monitoring in patients undergoing CPB for elective cardiac surgery. However, both tests were affected significantly after initiating CPB and aprotinin infusion.