Paolo Persona

Comparison of two methods for cardiac output measurement in critically ill patients

BACKGROUND The aim of recent haemodynamic monitoring has been to obtain continuous and reliable measures of cardiac output (CO) and indices of preload responsiveness. Many of these methods are based on the arterial pressure waveform analysis. The aim of our study was to assess the accuracy of CO measurements obtained by FloTrac/Vigileo, software version 1.07 and the new version 1.10 (Edwards Lifesciences LLC, Irvine, CA, USA), compared with CO measurements obtained by bolus thermodilution by pulmonary artery catheterization (PAC) in the intensive care setting. METHODS In 21 critically ill patients (enrolled in two University Hospitals), requiring invasive haemodynamic monitoring, PAC and FloTrac/Vigileo transducers connected to the arterial pressure line were placed. Simultaneous measurements of CO by two methods (FloTrac/Vigileo and thermodilution) were obtained three times a day for 3 consecutive days, when possible. The level of concordance between the two methods was assessed by the procedure suggested by Bland and Altman. RESULTS One hundred and forty-one pairs of measurements (provided by thermodilution and by both 1.07 and 1.10 FloTrac/Vigileo versions) were obtained in 21 patients (seven of them were trauma patients) with a mean (sd) age of 59 (16) yr. The Pearson product moment coefficient was 0.62 (P<0.001). The bias was -0.18 litre min(-1). The limits of agreement were 4.54 and -4.90 litre min(-1), respectively. CONCLUSIONS Our data show a poor level of concordance between measures provided by the two methods. We found an underestimation of CO values measured with the 1.07 software version of FloTrac for supranormal values of CO. The new software (1.10) has been improved in order to correct this bias; however, its reliability is still poor. On the basis of our data, we can therefore conclude that both software versions of FloTrac/Vigileo did not still provide reliable estimation of CO in our intensive care unit setting.

Comparison Between Doppler-echocardiography and Uncalibrated Pulse Contour Method for Cardiac Output Measurement: A Multicenter Observational Study*

Objectives: Echocardiography and pulse contour methods allow, respectively, noninvasive and less invasive cardiac output estimation. The aim of the present study was to compare Doppler echocardiography with the pulse contour method MostCare for cardiac output estimation in a large and nonselected critically ill population. Design: A prospective multicenter observational comparison study. Setting: The study was conducted in 15 European medicosurgical ICUs. Patients: We assessed cardiac output in 400 patients in whom an echocardiographic evaluation was performed as a routine need or for cardiocirculatory assessment. Interventions: None. Measurements and Main Results: One echocardiographic cardiac output measurement was compared with the corresponding MostCare cardiac output value per patient, considering different ICU admission categories and clinical conditions. For statistical analysis, we used Bland-Altman and linear regression analyses. To assess heterogeneity in results of individual centers, Cochran Q, and the I 2 statistics were applied. A total of 400 paired echocardiographic cardiac output and MostCare cardiac output measures were compared. MostCare cardiac output values ranged from 1.95 to 9.90 L/min, and echocardiographic cardiac output ranged from 1.82 to 9.75 L/min. A significant correlation was found between echocardiographic cardiac output and MostCare cardiac output (r = 0.85; p < 0.0001). Among the different ICUs, the mean bias between echocardiographic cardiac output and MostCare cardiac output ranged from –0.40 to 0.45 L/min, and the percentage error ranged from 13.2% to 47.2%. Overall, the mean bias was –0.03 L/min, with 95% limits of agreement of –1.54 to 1.47 L/min and a relative percentage error of 30.1%. The percentage error was 24% in the sepsis category, 26% in the trauma category, 30% in the surgical category, and 33% in the medical admission category. The final overall percentage error was 27.3% with a 95% CI of 22.2–32.4%. Conclusions: Our results suggest that MostCare could be an alternative to echocardiography to assess cardiac output in ICU patients with a large spectrum of clinical conditions.

Non-invasive ventilation in prone position for refractory hypoxemia after bilateral lung transplantation

Abstract:  Temporary graft dysfunction with gas exchange abnormalities is a common finding during the postoperative course of a lung transplant and is often determined by the post‐reimplantation syndrome. Supportive measures including oxygen by mask, inotropes, diuretics, and pulmonary vasodilators are usually effective in non‐severe post‐reimplantation syndromes. However, in less‐responsive clinical pictures, tracheal intubation with positive pressure ventilation, or non‐invasive positive pressure ventilation (NIV), is necessary. We report on the clinical course of two patients suffering from refractory hypoxemia due to post‐reimplantation syndrome treated with NIV in the prone and Trendelenburg positions. NIV was well tolerated and led to resolution of atelectactic areas and dishomogeneous lung infiltrates. Repeated turning from supine to prone under non invasive ventilation determined a stable improvement of gas exchange and prevented a more invasive approach. Even though NIV in the prone position has not yet entered into clinical practice, it could be an interesting option to achieve a better match between ventilation and perfusion. This technique, which we successfully applied in lung transplantation, can be easily extended to other lung diseases with non‐recruitable dorso‐basal areas.

Anticoagulation with citrate for hemodiafiltration in an acute bleeding trauma

The correct management of acute kidney injury (AKI) in severe trauma patients still represents a major therapeutic challenge. Continuous veno-venous hemodiafiltration (CVVHDF) with high pore filter (HPF) and regional citrate anticoagulation has recently been proposed as a valid therapeutic option in patients with crash syndrome-related AKI and high hemorrhagic risk (1). Nonetheless, the results of this new approach on critical trauma patients are still largely unknown. We report the case of a patient with post-traumatic AKI, secondary to massive rhabdomyolysis, and uncontrolled active bleeding. The safety and the effectiveness of CVVHDF with citrate and its possible clinical implications in trauma patients are briefly discussed. A young woman involved in a car crash was referred to the trauma center of our hospital with a massive retroperitoneal hematoma due to rupture of the left hypogastric artery. An angiographic procedure to control the bleeding failed. She was admitted to the intensive care unit (ICU) where a diagnosis of massive ischemic rhabdomyolysis due to femoral artery flow reduction was established (myoglobin levels >100,000 ug/l). Blood tests showed severe lactic acidosis (pH 7.17, lactate 11.9 mmol/l), decreased hemoglobin (Hb 6.6 g/dl) and platelet levels (27 × 109/l). Despite aggressive management with mechanical ventilation, adequate volume expansion and hemodynamic support by norepinephrine (0.2 mcg/kg/min), the patient developed AKI. After consultation with nephrologists, continuous renal replacement therapy (CRRT), with HPF, was undertaken at Qb of 120 ml/min. CVVHDF-associated anticoagulation was based on the regional administration of 3 mmol citrate/l blood flow. During CVVHDF, the bleeding ceased and the hemodynamics improved. Serum albumin, calcium, magnesium, and phosphate were closely monitored and adjusted. Norepinephrine was discontinued from the third day and 2 units of PRBC were needed to maintain Hb level above 8 g/dl. After 5 days, CVVHDF was suspended and renal function normalized (Fig. 1). Concomitant acute bleeding and rhabdomyolysis are not infrequent in trauma patients (1) and the development of AKI represents an independent risk factor for mortality (2). The treatment of this condition usually requires intravascular volume expansion and forced diuresis (3), but sometimes CVVHDF is needed (4). In conclusion, CVVHDF with sodium citrate has been indicated as a valid therapeutic option for patients with AKI and high hemorrhagic risk. To the best of our knowledge, this case provides the first evidence of its utility even in patients with ongoing acute bleeding. Further studies are needed to confirm its usefulness and safety for the treatment of traumarelated renal failure.

Lung ultrasound as a monitoring tool in lung transplantation in rodents: a feasibility study

Background Orthotopic lung transplantation in rats has been developed as a model to study organ dysfunction, but available tools for monitoring the graft function are limited. In this study, lung ultrasound (LUS) is proposed as a new non-invasive monitoring tool in awake rodents. Methods LUS was applied to native and graft lung of six rats after left orthotopic transplantation. Rats were monitored with LUS while awake, patterns identified, images evaluated with a scoring system, intra- and inter-rater agreement was assessed and examination times analyzed. Results A total of 78 clips were recorded. The median quality score of LUS was 3.66/4 for left hemithorax and 3.71/4 for native right side. The intra-rater agreement was 0.53 and 0.65 and the inter-rater agreement was 0.61 (P<0.01). Median time to complete the examination was 233.0 seconds (IQR 142) for both lungs, lowered from 254.0 seconds (IQR 129.5) (first trimester of study) to 205.5 seconds (IQR 88.5) (second trimester of the study). Significant findings on LUS were confirmed on pathological examination. Conclusions LUS in awake rodents without shaving has been shown to be both feasible and safe and the images collected were of good quality and comparable to those obtained in anesthetized rats without bristles.

Simulation in Anaesthesia and Intensive Care

Simulation can be considered as an attempt to reproduce real or imaginary environments and systems to study the behaviours of the subjects and the consequences of their actions in real time. Anaesthesia seems to be an ideal field where simulation can offer advantages without risks. New concepts in medical education consider more structured and planned curricula and the need to gain and to maintain competence in all aspects of clinical practice. Some institutions as US FDA, American College of Surgeons (ACS), American Board of Anaesthesiologists (ABA) have already required a simulation-based training for some of their qualifications. Some errors are inevitable, but living errors in a simulation setting can allow participants to improve their emotional control and to have a better management of the situation if it happens again with live patients. A simulation project is an expensive project and a good manager must plan a financial draft to let a simulation centre to survive. The cost-effectiveness of a simulation-based medical educational programme must be considered in terms of improvement of clinical competence, patient safety and error reduction in the era of limited resources.