ECMELLA as a bridge to heart transplantation in refractory ventricular fibrillation: A case report.

Background: Extracorporeal membrane oxygenation (ECMO) is an effective cardiorespiratory support technique in refractory cardiac arrest (CA). In patients under veno-arterial ECMO, the use of an Impella device, a microaxial pump inserted percutaneously, is a valuable strategy through a left ventricular unloading approach. ECMELLA, a combination of ECMO with Impella, seems to be a promising method to support end-organ perfusion while unloading the left ventricle. Case summary: The present case report describes the clinical course of a patient with ischemic and dilated cardiomyopathy who presented with refractory ventricular fibrillation (VF) leading to CA in the late postmyocardial infarction (MI) period, and who was successfully treated with ECMO and IMPELLA as a bridge to heart transplantation. Discussion: In the case of CA on VF refractory to conventional resuscitation maneuvers, early extracorporeal cardiopulmonary resuscitation (ECPR) associated with an Impella seems to be the best strategy. It provides organ perfusion, left ventricular unloading, and ability for neurological evaluation and VF catheter ablation before allowing heart transplantation. It is the treatment of choice in cases of end-stage ischaemic cardiomyopathy and recurrent malignant arrhythmias.

[Cardiac surgery in the time of COVID19 - A narrative of three very unusual cases and lessons learned]. / Chirurgie cardiaque au temps du Covid-19 - Récit de trois cas très inhabituels et leçons retenues.

COVID19 altered and impacted medical and surgical practice around the world. Standard of care and routine procedures are disrupted. Majors shift in personnel, and ad hoc new team as well as delocalization and working with new infrastructures are further challenges to be dealt with. This review of three very unusual scenarios illustrates pitfalls and dangers harbored in the re-shaped landscape of COVID19 exemplifying the narrow path bridging from the medical and surgical comfort zone to uncharted territory and eventually leading to collateral damage.

Le Covid-19 a profondément modifié et sévèrement impacté les pratiques médicales et chirurgicales à long terme. Les standards de prise en charge et les procédures de routine sont altérés, voire perturbés. Des mutations majeures au niveau du personnel et des équipes de même que la délocalisation ou le travail avec de nouvelles infrastructures sont autant de défis à relever, encore aujourd'hui. Trois scénarios inhabituels illustrent les pièges et les dangers qui se cachent dans le paysage marqué par le Covid-19. Ces exemples démontrent la marge étroite entre la zone de confort médicale et chirurgicale classique et l'appréhension d'une situation inhabituelle qui risque d'entraîner des dommages collatéraux pour les patients.

Coronavirus disease 2019-associated coronary endotheliitis and thrombotic microangiopathy causing cardiogenic shock: a case report.

Background: Coronavirus disease 2019 (COVID-19) primarily affects the respiratory tract but serious cardiovascular complications have been reported. Up to one-third of patients admitted to the intensive care unit may develop an acute myocardial injury, characterized by cardiac troponin elevation. However, the pathology underlying COVID-19-associated myocardial injury has rarely been reported. Case summary: Three days after being diagnosed for a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, a 52-year-old woman without a notable past medical history developed cardiogenic shock with severely reduced left ventricular ejection fraction (LVEF) at 25%. Coronary angiography was normal. Endomyocardial biopsy demonstrated coronary endotheliitis with multiple microvascular thromboses but no lymphocytic infiltrate and a negative polymerase chain reaction for SARS-CoV-2. The patient was implanted with a short-term LV assist device (Impella CP®, Abiomed, Aachen, Germany) and treated with therapeutic anticoagulation. She suffered from concomitant respiratory failure that required 14 days of orotracheal intubation, 10 days of dexamethasone, and broad-spectrum antibiotics. Clinical outcome was favourable with weaning of the Impella device after 6 days and full recovery of LVEF (65%) at 30 days. Cardiac magnetic resonance performed at Day 30 showed no evidence of myocarditis or scars and confirmed the normalization of LVEF. Discussion: This case highlights how COVID-19-associated coronary endotheliitis and thrombotic microangiopathy, in the absence of myocarditis, may induce transient severe LV dysfunction and cardiogenic shock.

Do ScvO2 variations induced by passive leg raising predict fluid responsiveness? A prospective study.

OBJECTIVE: The present study investigates whether ScvO2 variations induced by passive leg raising (PLR) are able to predict fluid responsiveness (FR) in mechanically ventilated patients. DESIGN: A monocentric prospective clinical study. SETTING: An intensive care division in a tertiary hospital. PATIENTS: The inclusion criteria were elective postoperative cardiac surgery patients who were over 18 years old, deeply sedated, mechanically ventilated and needed volume expansion (VE). Fluid responders (R) were defined as patients who increased their left ventricular outflow tract velocity time integral (VTI) ≥15% after VE. INTERVENTION: In patients included in this study, continuous ScvO2  monitoring (CeVOX device, Pulsion Medical Systems) and VTI (transthoracic echocardiography) were measured simultaneously before and during a PLR test and before and after VE (with 500 ml of saline). MEASUREMENTS AND MAIN RESULTS: Thirty-three consecutive patients were included in this study. In 15 patients with a positive PLR test (increase in VTI ≥15%), ScvO2 increased during PLR by 9 ± 4%. In the 18 patients with a negative PLR test, ScvO2 did not significantly change during PLR. VE increased ScvO2 by 9 ± 6% and 2 ± 4% in responders and nonresponders, respectively. If ScvO2 increased by >4% during the PLR test, then a positive VTI response (≥15%) was diagnosed with a sensitivity of 93% (68-99%) and a specificity of 94% (63-99%) (Area under the receiver operating characteristic curve 0.92 ± 0.58, p < 0.05). Moreover, ScvO2 variations were able to distinguish responders to VE from nonresponders to VE with a sensitivity of 87% (68-99%) and a specificity of 89% (63-99%) (Area under the receiver operating characteristic curve 0.89 ± 0.07, p < 0.05). CONCLUSIONS: ScvO2 variation induced by PLR is a reliable, minimally invasive parameter for predicting FR at the postoperative cardiac surgery bedside of mechanically ventilated, critically ill patients.

Pathophysiology of COVID-19: Everywhere You Look You Will See ACE2!

Angiotensin converting enzyme 2 (ACE2) seems to be a central actor in the pathophysiology of SARS-Cov-2 infection. First, it acts as the receptor for the virus and permits its attachment to cells expressing ACE2. Second, the relative deficiency of ACE2 during infection could be linked to several clinical features encountered during the disease, like ARDS and coagulation abnormalities. This study explores the strong link between ACE2 and the majority of risk factors for the severe evolution of COVID-19. It seems that all these risks factors are linked to an increased level of ACE2 and/or imbalance in ACE/ACE2.

Burkitt lymphoma and lactic acidosis: A case report and review of the literature.

Type A lactic acidosis is a potentially life-threatening complication in critically ill patients and is the hallmark of a shock state as a result of tissue hypoperfusion and dysoxia. Type B lactic acidosis results from mechanisms other than dysoxia and is a rare condition in patients with solid tumors or hematological malignancies. We present a case of a 60-year-old man with lactic acidosis who was found to have a Burkitt lymphoma related to a posttransplant lymphoproliferative disorder. Lactagenic cancers are characterized by increased aerobic glycolysis and excessive lactate formation, a phenomenon described by Warburg in 1923 that is correlated with cancer aggressiveness and poor survival. There is increased glucose utilization with the purpose of lactagenesis under fully oxygenated conditions, as lactate seems to be a potent signaling molecule for angiogenesis, immune escape, cell migration, metastasis and self-sufficient metabolism, which are five essential steps of carcinogenesis. Type B lactic acidosis in association with malignancies carries an extremely poor prognosis. Currently, effective chemotherapy seems to be the only hope for survival.

Respiratory changes in subclavian vein diameters predicts fluid responsiveness in intensive care patients: a pilot study.

The present pilot study investigated whether respiratory variation in subclavian vein (SCV) diameters correlates with fluid responsiveness in mechanically ventilated patients. Monocentric, prospective clinical study on fluid responsiveness in adult sedated, mechanically ventilated ICU patient, monitored with the PiCCO™ system (Pulsion Medical System, Germany), and requiring a fluid challenge (FC). A 10-min fluid bolus of 500 mL of 0.9% saline was administered. Cardiac output (CO) and dynamic parameters [stroke volume variation (SVV) and pulse pressure variation (PPV)] measured by transpulmonary thermodilution and pulse contour analysis (PiCCO™) as well as classical hemodynamic parameters were recorded at baseline and after FC. Fluid responsiveness was described as an increase in CO of ≥ 15%. Ultrasound measurements obtained in the subclavian long-axis view were used to calculate the SCVvariability index. A cut-off value for SCV variation for the prediction of fluid responsiveness was determined using receiver operating curve (ROC) analysis. Nine of 20 FCs (45%) induced an increase in CO of ≥ 15%. At baseline, the SCVvariability index was greater in responders than in non-responders (34.0 ± 21.4 vs. 9.0 ± 5.5; p = 0.0005). Diagnostic performance for the SCVvariability index revealed a cut-off value of 14 with a sensitivity of 100% [Confidence interval (CI) 95% (90; 100)] and a specificity of 82% [CI 95% (48; 98)] for the prediction of fluid responsiveness. Other parameters, such as SVV and PPV, could not predict fluid responsiveness. The correlation coefficient between CO variation and the SCVvariability index was 0.73 (p < 0.001). The SCVvariability index was a reliable, non-invasive parameter for the prediction of fluid responsiveness at the bedside of mechanically ventilated, critically ill patients in this pilot study.

Effects of acute hemorrhage on intrapulmonary shunt in a pig model of acute respiratory distress-like syndrome.

BACKGROUND: In acute respiratory distress syndrome (ARDS), gas exchange and respiratory system mechanics (compliance) are severely impaired. Besides ventilatory parameters, the degree of respiratory abnormality can be influenced by the circulatory state. This study investigated the influence of acute hypovolemia on the respiratory system. METHODS: We performed a secondary analysis of a previous study including 8 pigs with ARDS-like syndrome induced by lung lavage and surfactant depletion method (ARDS group) and 10 mechanically ventilated pigs with no intervention (CTRL group). Animals of both groups were subjected to hemorrhage and retransfusion successively. We reanalyzed the effect of acute blood volume variations on intrapulmonary shunt (shunt), arterial oxygenation (PaO2:FiO2), global oxygen delivery (DO2) and respiratory system compliance (Crs). RESULTS: In the ARDS group, after hemorrhage, shunt decreased (-28 +/- 3.5 % (p < 0.001)), respiratory system compliance (Crs) increased (+5.1 +/- 1.0 ml/cm H2O (p < 0.001)) moreover, there was a concurrent increase in PaO2:FiO2 (+113 +/- 19.1 mmHg; p < 0.001) but this did not prevent a reduction in DO2 (-317 +/- 49.8 ml/min; p < 0.001). Following retransfusion, shunt and Crs return towards pre-hemorrhage values. Similar changes, but of smaller magnitude were observed in the CTRL group, except that no significant changes in oxygenation occurred. CONCLUSIONS: The present analysis suggests that an acute decrease in blood volume results in a decrease in shunt with a parallel improvement in arterial oxygenation and an increase in Crs during ARDS-like syndrome. Our results strengthen the importance to integrate the circulatory condition in the analysis of the state of the respiratory system. However, the translation of this physiological model in a clinical perspective is not straightforward because our model of acute and severe hemorrhage is not strictly equivalent to a progressive hypovolemia, as could be obtained in ICU by diuretic. Furthermore, the present model does not consider the impact of blood loss induced decrease of DO2 on other vital organs function. TRIAL REGISTRATION: 'Not applicable'.

ShockOmics: multiscale approach to the identification of molecular biomarkers in acute heart failure induced by shock.

BACKGROUND: The ShockOmics study (ClinicalTrials.gov identifier NCT02141607) is a multicenter prospective observational trial aimed at identifying new biomarkers of acute heart failure in circulatory shock, by means of a multiscale analysis of blood samples and hemodynamic data from subjects with circulatory shock. METHODS AND DESIGN: Ninety septic shock and cardiogenic shock patients will be recruited in three intensive care units (ICU) (Hôpital Erasme, Université Libre de Bruxelles, Belgium; Hospital Universitari Mutua Terrassa, Spain; Hôpitaux Universitaires de Genève, Switzerland). Hemodynamic signals will be recorded every day for up to seven days from shock diagnosis (time T0). Clinical data and blood samples will be collected for analysis at: i) T1 < 16 h from T0; ii) T2 = 48 h after T0; iii) T3 = day 7 or before discharge or before discontinuation of therapy in case of fatal outcome; iv) T4 = day 100. The inclusion criteria are: shock, Sequential Organ Failure Assessment (SOFA) score > 5 and lactate levels ≥ 2 mmol/L. The exclusion criteria are: expected death within 24 h since ICU admission; > 4 units of red blood cells or >1 fresh frozen plasma transfused; active hematological malignancy; metastatic cancer; chronic immunodepression; pre-existing end stage renal disease requiring renal replacement therapy; recent cardiac surgery; Child-Pugh C cirrhosis; terminal illness. Enrollment will be preceded by the signature of the Informed Consent by the patient or his/her relatives and by the physician in charge. Three non-shock control groups will be included in the study: a) healthy blood donors (n = 5); b) septic patients (n = 10); c) acute myocardial infarction or patients with prolonged acute arrhythmia (n = 10). The hemodynamic data will be downloaded from the ICU monitors by means of dedicated software. The blood samples will be utilized for transcriptomics, proteomics and metabolomics ("-omics") analyses. DISCUSSION: ShockOmics will provide new insights into the pathophysiological mechanisms underlying shock as well as new biomarkers for the timely diagnosis of cardiac dysfunction in shock and quantitative indices for assisting the therapeutic management of shock patients.

Impact of early haemodynamic goal-directed therapy in patients undergoing emergency surgery: an open prospective, randomised trial.

Haemodynamic goal-directed therapies (GDT) may improve outcome following elective major surgery. So far, few data exist regarding haemodynamic optimization during emergency surgery. In this randomized, controlled trial, 50 surgical patients with hypovolemic or septic conditions were enrolled and we compared two algorithms of GDTs based either on conventional parameters and pressure pulse variation (control group) or on cardiac index, global end-diastolic volume index and stroke volume variation as derived from the PiCCO monitoring system (optimized group). Postoperative outcome was estimated by a composite index including major complications and by the Sequential Organ Failure Assessment (SOFA) Score within the first 3 days after surgery (POD1, POD2 and POD3). Data from 43 patients were analyzed (control group, N = 23; optimized group, N = 20). Similar amounts of fluid were given in the two groups. Intraoperatively, dobutamine was given in 45 % optimized patients but in no control patients. Major complications occurred more frequently in the optimized group [19 (95 %) versus 10 (40 %) in the control group, P < 0.001]. Likewise, SOFA scores were higher in the optimized group on POD1 (10.2 ± 2.5 versus 6.6 ± 2.2 in the control group, P = 0.001), POD2 (8.4 ± 2.6 vs 5.0 ± 2.4 in the control group, P = 0.002) and POD 3 (5.2 ± 3.6 and 2.2 ± 1.3 in the control group, P = 0.01). There was no significant difference in hospital mortality (13 % in the control group and 25 % in the optimized group). Haemodynamic optimization based on volumetric and flow PiCCO-derived parameters was associated with a less favorable postoperative outcome compared with a conventional GDT protocol during emergency surgery.

Successful heart transplantation after prolonged cardiac arrest and extracorporeal life support in organ donor-a case report.

BACKGROUND: Although heart transplantation is a successful therapy for patients suffering from end-stage heart failure, the therapeutic is limited by the lack of organs. Donor cardiac arrest is a classic hindrance to heart retrieval as it raises issues on post-transplant outcomes. CASE PRESENTATION: The present case reports a successful heart transplantation after prolonged donor cardiac arrest (total lowflow time of 95 minutes) due to anaphylactic shock necessitating extracorporeal life support. We further provide an overview of the current evidence and outcomes of heart transplantation in cases of donor cardiac arrest. CONCLUSION: Providing that donor and recipient criteria are respected, donor cardiac arrest does not seem to be an adverse predictor in heart transplantation.

Percutaneous Aortic Balloon Valvuloplasty and Intracardiac Adrenaline in Electromechanical Dissociation as Bridge to Transcatheter Aortic Valve Implantation.

This report describes an emergent balloon aortic valvuloplasty (BAV) procedure performed under cardiopulmonary resuscitation in a 79-year-old man with severe symptomatic aortic stenosis (mean gradient 78 mm Hg, valve area 0.71 cm, and left ventricular ejection fraction 40%) awaiting surgery and who was admitted for heart failure rapidly evolving to cardiogenic shock and multiorgan failure. Decision was made to perform emergent BAV. After crossing the valve with a 6 French catheter, the patient developed an electromechanical dissociation confirmed at transesophageal echocardiography and cardiac arrest. Manual chest compressions were initiated along with the application of high doses of intravenous adrenaline, and BAV was performed under ongoing resuscitation. Despite BAV, transoesophageal echocardiography demonstrated no cardiac activity. At this point, it was decided to advance a pigtail catheter over the wire already in place in the left ventricle and to inject intracardiac adrenaline (1 mg, followed by 5 mg). Left ventricular contraction progressively resumed and, in the absence of aortic regurgitation, an intraaortic balloon pump was inserted. The patient could be weaned from intraaortic balloon pump and vasopressors on day 1, extubated on day 6, and recovered from multiorgan failure. In the absence of neurologic deficits, he underwent uneventful transcatheter aortic valve implantation on day 12 and was discharged to a cardiac rehabilitation program on day 30. At 3-month follow-up, he reported dyspnea NYHA class II as the only symptom.This case shows that severe aortic stenosis leading to electromechanical dissociation may be treated by emergent BAV and intracardiac administration of high-dose adrenaline. Intracardiac adrenaline may be considered in case of refractory electromechanical dissociation occurring in the cardiac catheterization laboratory.

Influence of intra-abdominal pressure on the specificity of pulse pressure variations to predict fluid responsiveness.

BACKGROUND: The positive predictive value of pulse pressure variations (ΔPP) to discriminate patients who should respond to volume expansion (VE) may be altered in mechanically ventilated patients. Our goal was to determine whether intra-abdominal pressure (IAP) measurements could discriminate patients with true-positive ΔPP values versus patients with false-positive ΔPP values. METHODS: We designed a prospective pathophysiologic study in a mixed intensive care unit of a university hospital. Sixteen mechanically ventilated patients with hypotension (SAP, <90 mm Hg) and with ΔPP of 13% or more were included. Cardiac output was assessed using Doppler echocardiography before and after VE; IAP was measured using the bladder pressure method. Patients were classified into two groups according to their response to a standardized VE (500 mL of NaCl 0.9%): responders (≥15% increase in cardiac output) and nonresponders. RESULTS: Nine patients (57%) were responders, and seven patients (43%) were nonresponders. Before VE, IAP was statistically higher in nonresponders (15 [11-22] mm Hg vs. 9 [6.5-11] mm Hg; p = 0.008). The area under the curve of the receiver operating characteristic curve was 0.9 ± 0.08. In patients with ΔPP of 13% or more, an IAP cutoff value of 10.5 mm Hg discriminated between responders and nonresponders with a sensitivity of 100% (59-100%) and a specificity of 78% (40-97%). CONCLUSION: An increase in IAP of more than 10.5 mm Hg can decrease the positive predictive value of ΔPP. Hence, in patients prone to present abnormal IAP values, IAP should be measured before performing VE directed by the ΔPP marker. LEVEL OF EVIDENCE: Diagnostic study, level II.

Impact of epinephrine and norepinephrine on two dynamic indices in a porcine hemorrhagic shock model.

BACKGROUND: Pulse pressure variations (PPVs) and stroke volume variations (SVVs) are dynamic indices for predicting fluid responsiveness in intensive care unit patients. These hemodynamic markers underscore Frank-Starling law by which volume expansion increases cardiac output (CO). The aim of the present study was to evaluate the impact of the administration of catecholamines on PPV, SVV, and inferior vena cava flow (IVCF). METHODS: In this prospective, physiologic, animal study, hemodynamic parameters were measured in deeply sedated and mechanically ventilated pigs. Systemic hemodynamic and pressure-volume loops obtained by inferior vena cava occlusion were recorded. Measurements were collected during two conditions, that is, normovolemia and hypovolemia, generated by blood removal to obtain a mean arterial pressure value lower than 60 mm Hg. At each condition, CO, IVCF, SVV, and PPV were assessed by catheters and flow meters. Data were compared between the conditions normovolemia and hypovolemia before and after intravenous administrations of norepinephrine and epinephrine using a nonparametric Wilcoxon test. RESULTS: Eight pigs were anesthetized, mechanically ventilated, and equipped. Both norepinephrine and epinephrine significantly increased IVCF and decreased PPV and SVV, regardless of volemic conditions (p < 0.05). However, epinephrine was also able to significantly increase CO regardless of volemic conditions. CONCLUSION: The present study demonstrates that intravenous administrations of norepinephrine and epinephrine increase IVCF, whatever the volemic conditions are. The concomitant decreases in PPV and SVV corroborate the fact that catecholamine administration recruits unstressed blood volume. In this regard, understanding a decrease in PPV and SVV values, after catecholamine administration, as an obvious indication of a restored volemia could be an outright misinterpretation.

Respiratory change in ECG-wave amplitude is a reliable parameter to estimate intravascular volume status.

Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-wave amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-wave amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-wave amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-wave amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS amplitude (ECGmax) and minimal QRS amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."

Clinical review: management of weaning from cardiopulmonary bypass after cardiac surgery.

A sizable number of cardiac surgical patients are difficult to wean off cardiopulmonary bypass (CPB) as a result of structural or functional cardiac abnormalities, vasoplegic syndrome, or ventricular dysfunction. In these cases, therapeutic decisions have to be taken quickly for successful separation from CPB. Various crisis management scenarios can be anticipated which emphasizes the importance of basic knowledge in applied cardiovascular physiology, knowledge of pathophysiology of the surgical lesions as well as leadership, and communication between multiple team members in a high-stakes environment. Since the mid-90s, transoesophageal echocardiography has provided an opportunity to assess the completeness of surgery, to identify abnormal circulatory conditions, and to guide specific medical and surgical interventions. However, because of the lack of evidence-based guidelines, there is a large variability regarding the use of cardiovascular drugs and mechanical circulatory support at the time of weaning from the CPB. This review presents key features for risk stratification and risk modulation as well as a standardized physiological approach to achieve successful weaning from CPB.

Continuous cardiac output monitoring after cardiopulmonary bypass: a comparison with bolus thermodilution measurement.

OBJECTIVE: The interchangeability of continuous measurement of cardiac output (CO) with the traditional bolus method in patients after cardiopulmonary bypass (CPB) is uncertain. DESIGN: Prospective observational clinical study. SETTING: A 20-bed surgical ICU at a university hospital. PATIENTS: Fourteen deeply sedated, ventilated, post-cardiac surgery patients, all equipped with a pulmonary artery catheter. INTERVENTIONS: Six hours after the end of the CPB, 56 simultaneous bolus and continuous measurements were compared by a linear regression analysis and Bland-Altman analysis. Bolus CO was estimated by averaging triplicate injections of 10 ml room-temperature NaCl 0.9%, delivered randomly during the respiratory cycle. A stringent maximum difference of 0.55 l min(-1) (about 10% of the mean bolus measured) was considered as a clinically acceptable agreement between the two types of measurements. To be interchangeable the limits of agreement (+/-2 SD of the mean difference between the two methods) should not exceed the chosen acceptable difference. MEASUREMENTS AND RESULTS: Continuous was correlated with bolus CO, with a correlation coefficient of r(2)=0.68. (p<0.01). The Bland-Altman analysis demonstrated an objective mean bias of 0.33+/-0.6 l min(-1) (confidence interval of -0.87-1.58) with 34% of measured values falling outside of the clinically acceptable limits. CONCLUSION: Our results suggest that, in the first 6 h after CPB, continuous and bolus CO determinations are not interchangeable; one third of the values obtained by continuous CO fell outside the strict limits of clinically useful precision.