Sandra Rossi

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.

Disaturated-phosphatidylcholine and Surfactant protein-B turnover in human acute lung injury and in control patients

BackgroundPatients with Adult Respiratory Distress Syndrome (ARDS) and Acute Lung Injury (ALI) have low concentrations of disaturated-phosphatidylcholine and surfactant protein-B in bronchoalveolar lavage fluid. No information is available on their turnover.ObjectivesTo analyze disaturated-phosphatidylcholine and surfactant protein-B turnover in patients with ARDS/ALI and in human adults with normal lungs (controls).Methods2H2O as precursor of disaturated-phosphatidylcholine-palmitate and 113C-Leucine as precursor of surfactant protein-B were administered intravenously to 12 patients with ARDS/ALI and to 8 controls. Disaturated-phosphatidylcholine and surfactant protein-B were isolated from serial tracheal aspirates, and their fractional synthetic rate was derived from the 2H and 13C enrichment curves, obtained by gas chromatography mass spectrometry. Disaturated-phosphatidylcholine, surfactant protein-B, and protein concentrations in tracheal aspirates were also measured.Results1) Surfactant protein-B turned over at faster rate than disaturated-phosphatidylcholine both in ARDS/ALI patients and in controls. 2) In patients with ARDS/ALI the fractional synthesis rate of disaturated-phosphatidylcholine was 3.1 times higher than in controls (p < 0.01), while the fractional synthesis rate of surfactant protein-B was not different. 3) In ARDS/ALI patients the concentrations of disaturated-phosphatidylcholine and surfactant protein-B in tracheal aspirates were markedly and significantly reduced (17% and 40% of the control values respectively).Conclusions1) Disaturated-phosphatidylcholine and surfactant protein-B have a different turnover both in healthy and diseased lungs. 2) In ARDS/ALI the synthesis of these two surfactant components may be differently regulated.

Comparison of invasive and noninvasive positive pressure ventilation delivered by means of a helmet for weaning of patients from mechanical ventilation

PURPOSE The effectiveness of noninvasive positive pressure ventilation delivered by helmet (H-NPPV) as a weaning approach in patients with acute respiratory failure is unclear. PATIENTS AND METHODS We randomly and evenly assigned 64 patients intubated for acute respiratory failure to conventional weaning with invasive mechanical ventilation (IMV) or H-NPPV. The primary end point was a reduction in IMV duration by 6 days between the 2 groups. Secondary end points were the occurrence of ventilator-associated pneumonia and major complications, duration of mechanical ventilation and weaning, intensive care unit and hospital length of stay, and survival. RESULTS The mean duration of IMV was significantly reduced in the H-NPPV group compared with the IMV group (P<.0001), without significant difference in duration of weaning (P=.26) and total ventilatory support (P=.45). In the H-NPPV group, the incidence of major complications was less than the IMV group (P=.032). Compared with the H-NPPV group, the IMV group was associated with a greater incidence of VAP (P=.018) and an increased risk of nosocomial pneumonia (P=.049). The mortality rate was similar between the groups, with no significant difference in overall intensive care unit (P=.47) or hospital length of stay (P=.37). CONCLUSIONS H-NPPV was well tolerated and effective in patients who were difficult to wean.

High-frequency percussive ventilation: a new strategy for separation from extracorporeal membrane oxygenation.

We report the case of a 48-year-old woman who developed severe septic shock and lung injury after community-acquired pneumonia. She was supported on arteriovenous extracorporeal membrane oxygenation (ECMO) for 19 days. To facilitate decannulation and separation from ECMO, we began trials of high-frequency percussive ventilation (HFPV) using the volumetric diffusive respiration ventilator VDR-4 (Percussionaire Corp, Sandpoint, Idaho) for 4 consecutive days (1 before and 3 after). Decannulation was achieved successfully, and the patient was transferred to the floor 3 months later. During the 4 days of HFPV, the chest radiograph improved, as did gas exchange and clearance of pulmonary secretions. HFPV may be a promising strategy for improving lung recruitment and airway clearance during separation from ECMO in the critically ill patient.

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.

Images in Anesthesiology: Bronchopleural Fistula Caused by the Incorrect Placement of the Enteral Feeding Tube

<zdoi;10.1097/ALN.0000000000001137> Anesthesiology, V 125 • No 4 805 October 2016 T HE positioning of a nasoenteric feeding tube (NET) in critically ill patients is usually considered to be an easy and safe procedure, but it may be the cause of severe complications such as transbronchial intubation, pneumonia, esophageal perforation, pneumothorax, pulmonary hemorrhage, and intracranial placement.1 Computed tomography scans without contrast (fig. A and B) describe a tracheobronchial insertion of the NET, complicated by a bronchopleural fistula. A multiplanar reconstruction image (fig. A) shows the NET advancing beyond the tracheostomy tube into the right inferior bronchus (thin arrow) and an associated moderate right pleural effusion (big arrow). A volume rendering technique image (fig. B) highlights the aerated lungs (pink areas) and shows the NET penetrating through the lung, with its tip reaching the pleural space into the costophrenic recess (white arrow). According to the literature, tube placement errors vary from 1.3 to 50% in adults.2 The correct position should always be checked before feeding is started. Among the methods suggested for confirming the correct positioning of the NET, the most widely used are auscultation of borborygmus during air injection with examination of the visual characteristics of aspirate, chest radiograph, and evaluation of gastric content with measurement of the pH, bilirubin, pepsin, trypsin, and carbon dioxide.3 The National Patient Safety Agency guidelines highlight the unreliability of certain methods, but recommend testing with a pH indicator paper (pH between 1 and 5.5 as the safe range) and chest radiograph images as the first-line check.2