Koichi Suehiro

Systemic vascular resistance has an impact on the reliability of the Vigileo-FloTrac system in measuring cardiac output and tracking cardiac output changes

BACKGROUND The aim of this study was to examine the ability of the Vigileo-FloTrac system to measure cardiac output (CO) and track changes in CO induced by increased vasomotor tone, under different states of systemic vascular resistance (SVR). METHODS Forty patients undergoing cardiac surgery were enrolled. Haemodynamic variables including CO measured by the Vigileo-FloTrac system (version 3.02) (APCO), CO measured by a pulmonary artery catheter (ICO), and SVR index (SVRI) were recorded before (T1) and 2 min after (T2) phenylephrine administration (100 μg). Bland and Altman analysis was used to compare ICO and APCO at T1. We used four-quadrant plots and polar plots to compare the trending abilities between ICO and APCO. Patients were divided into three groups according to the SVRI value at T1, with low (<1200 dyn cm(-5) m(2)), normal (1200-2500 dyn cm(-5) m(2)), and high (>2500 dyn cm(-5) m(2)) SVRI states. RESULTS A total of 155 paired data were collected. The adjusted percentage error was 46.3%, 26.4%, and 61.4%, and the concordance rate between ΔICO and ΔAPCO was 67.5%, 28.8%, and 7.7% in the low, normal, and high SVRI state, respectively. The polar plot analysis showed that the mean angular bias was -22.3°, -46.0°, and -3.51°, and the radial limits of agreement were 70°, 85°, and 87°, in the low, normal, and high SVRI state, respectively. CONCLUSIONS These results indicate that the reliability of the Vigileo-FloTrac system to measure CO and track changes in CO induced by phenylephrine administration was not clinically acceptable.

Accuracy and precision of non-invasive cardiac output monitoring devices in perioperative medicine: a systematic review and meta-analysis†

Cardiac output (CO) measurement is crucial for the guidance of therapeutic decisions in critically ill and high-risk surgical patients. Newly developed completely non-invasive CO technologies are commercially available; however, their accuracy and precision have not recently been evaluated in a meta-analysis. We conducted a systematic search using PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science to review published data comparing CO measured by bolus thermodilution with commercially available non-invasive technologies including pulse wave transit time, non-invasive pulse contour analysis, thoracic electrical bioimpedance/bioreactance, and CO2 rebreathing. The non-invasive CO technology was considered acceptable if the pooled estimate of percentage error was <30%, as previously recommended. Using a random-effects model, sd, pooled mean bias, and mean percentage error were calculated. An I2 statistic was also used to evaluate the inter-study heterogeneity. A total of 37 studies (1543 patients) were included. Mean CO of both methods was 4.78 litres min−1. Bias was presented as the reference method minus the tested methods in 15 studies. Only six studies assessed the random error (repeatability) of the tested device. The overall random-effects pooled bias (limits of agreement) and the percentage error were −0,13 [−2.38 , 2.12] litres min−1 and 47%, respectively. Inter-study sensitivity heterogeneity was high (I2=83%, P<0.001). With a wide percentage error, completely non-invasive CO devices are not interchangeable with bolus thermodilution. Additional studies are warranted to demonstrate their role in improving the quality of care.

Goal-Directed fluid therapy with closed-loop assistance during moderate risk surgery using noninvasive cardiac output monitoring: A pilot study

BACKGROUND Goal directed fluid therapy (GDFT) has been shown to improve outcomes in moderate to high-risk surgery. However, most of the present GDFT protocols based on cardiac output optimization use invasive devices and the protocols may require significant practitioner attention and intervention to apply them accurately. The aim of this prospective pilot study was to evaluate the clinical feasibility of GDFT using a closed-loop fluid administration system with a non-invasive cardiac output monitoring device (Nexfin™, BMEYE, Amsterdam, Netherlands). METHODS Patients scheduled for elective moderate risk surgery under general anaesthesia were enrolled. The primary anaesthesia team managing the case selected GDFT targets using the controller interface and all patients received a baseline 3 ml kg(-1) h(-1) crystalloid infusion. Colloid solutions were delivered by the closed-loop system for intravascular volume expansion using data from the Nexfin™ monitor. Compliance with GDFT management was defined as acceptable when a patient spent more than 85% of the surgery time in a preload independent state (defined as pulse pressure variation <13%) or when average cardiac index during surgery was >2.5 litre min(-1) m(-2). RESULTS A total of 13 patients were included in the study group. All patients met the established criteria for delivery of GDFT for greater than 85% of case time. The median length of stay in the hospital was 5 [3-6] days. CONCLUSION In this pilot study, GDFT management using the closed-loop fluid administration system with a non-invasive CO monitoring device was feasible and maintained a high rate of protocol compliance. CLINICAL TRIAL REGISTRATION NCT02020863.

Improved Performance of the Fourth-Generation FloTrac/Vigileo System for Tracking Cardiac Output Changes

OBJECTIVES The aims of this study were to compare cardiac output (CO) measured by the new fourth-generation FloTrac™/Vigileo™ system (Version 4.00) (COFVS) with that measured by a pulmonary artery catheter (COREF), and to investigate the ability of COFVS to track CO changes induced by increased peripheral resistance. DESIGN Prospective study. SETTING University Hospital. PARTICIPANTS Twenty-three patients undergoing cardiac surgery. INTERVENTIONS Phenylephrine (100 µg) was administered. MEASUREMENTS AND MAIN RESULTS Hemodynamic variables, including CO(REF) and CO(FVS), were measured before and after phenylephrine administration. Bland-Altman analysis was used to assess the discrepancy between CO(REF) and CO(FVS). Four-quadrant plot and polar-plot analyses were utilized to evaluate the trending ability of CO(FVS) against CO(REF) after phenylephrine boluses. One hundred thirty-six hemodynamic interventions were performed. The bias shown by the Bland-Altman analysis was-0.66 L/min, and the percentage error was 55.4%. The bias was significantly correlated with the systemic vascular resistance index (SVRI) before phenylephrine administration (p<0.001, r(2) = 0.420). The concordance rate determined by four-quadrant plot analysis and the angular concordance rate calculated using polar-plot analysis were 87.0% and 83.0%, respectively. Additionally, this trending ability was not affected by SVRI state. CONCLUSIONS The trending ability of the new fourth-generation FloTrac™/Vigileo™ system after increased vasomotor tone was greatly improved compared with previous versions; however, the discrepancy of the new system in CO measurement was not clinically acceptable, as in previous versions. For clinical application in critically ill patients, this vasomotor tone-dependent disagreement must be decreased.

Relationship between noradrenaline release in the locus coeruleus and antiallodynic efficacy of analgesics in rats with painful diabetic neuropathy.

AIMS In animal models of neuropathic pain, the noradrenergic descending pain inhibitory pathways from the locus coeruleus (LC) may be suppressed. However, no study has investigated the correlation between noradrenaline (NA) release in the LC and efficacy of analgesics in rats with painful diabetic neuropathy. Using microdialysis and analysis of mechanical hypersensitivity, we investigated the correlation between NA release in the LC and efficacy of morphine, tramadol, and clomipramine in rats with diabetic mellitus (DM). MAIN METHODS In freely moving rats, basal NA concentrations in LC perfusate were quantitated 72 to 96 h after microdialysis probe implantation. Following intravenous administration of each drug, NA concentrations were expressed as a percentage of basal values. We concurrently measured the threshold to elicit a paw withdrawal response every 20 min for 80 min. KEY FINDINGS NA concentrations in the LC perfusate were significantly higher in the tramadol and clomipramine groups compared to the morphine group. Naloxone administration did not significantly affect NA concentrations. In the morphine group, NA release in the LC was not significantly correlated with the pain threshold. In contrast, in the tramadol and clomipramine groups, NA release in the LC was significantly correlated with the pain threshold. The correlation coefficient was higher in the clomipramine group than in the tramadol group. SIGNIFICANCE Our results suggest that the descending noradrenergic pathway can play an important role in analgesia for DM neuropathy and that there is a significant correlation between NA release in the LC and the efficacy of tramadol and clomipramine.

Perioperative management of a neonate with Cantrell syndrome.

Cantrell syndrome is a congenital malformation with a pentalogy characterized by defects involving the abdominal wall, lower sternum, anterior diaphragm, and diaphragmatic pericardium, as well as congenital cardiac anomalies. We recently managed anesthesia in a patient with this syndrome and herein report our experience. The patient was a 14-day-old male neonate, who had been diagnosed with Cantrell syndrome, including ventricular septal defect, left ventricular diverticulum, abdominal wall defect, omphalocele, and sternal hypoplasia. Surgical interventions to close the ventricular septal defect, resect the left ventricular diverticulum, and close the omphalocele were scheduled. After cardiac surgery, the hernial contents were returned to their original compartment and, subsequently, an attempt was made to suture the abdominal wall. However, blood pressure fell markedly and the attempt was discontinued. The chest was left open postoperatively and the patient was transferred to the intensive care unit (ICU), during which time circulatory and respiratory management was very complex. Issues requiring particular attention in the management of anesthesia for patients with this syndrome include complications of diverse cardiac malformations, pulmonary hypertension, pulmonary hypoplasia, and respiratory and circulatory failure associated with increased intraabdominal pressure due to primary closure of the omphalocele. Accordingly, extreme caution must be taken to restore respiratory and circulatory control.

The Vigileo-FloTracTM System: Arterial Waveform Analysis for Measuring Cardiac Output and Predicting Fluid Responsiveness: A Clinical Review

Surgical mortality rates range from 0.4% to 4%, with the occurrence of perioperative complications ranging from 3% to 17%. 2–5 These perioperative complications typically lead to an increase in the “unnecessary” days of hospitalization after surgery. Therefore, identifying high-risk patients and developing strategies aimed at decreasing perioperative complications are issues of great importance for anesthesiologists. Various interventions aimed at improving surgical outcomes have been examined by previous studies, including goal-directed therapy (GDT), 6–10 glycemic control, 11,12 and neuraxial blockade. 13–15 In a recent review, it has been suggested that interventions such as hemodynamic optimization, oxygen, glycemic control, and neuraxial anesthesia might decrease perioperative mortality. 16 Inadequate tissue perfusion has been indicated to be the strongest intraoperative predictor of perioperative complications. 17 For high-risk surgical patients, the main cause of perioperative mortality is more often related to inadequate tissue perfusion than to cardiac events. 18 Perioperative hemodynamic management can lead successfully to the optimization of cardiac output and ensure adequate oxygen delivery to the tissues; this has been shown to improve postoperative outcomes and reduce the length of the hospital stay. 7,10,19–23 In several studies that focused on cardiac output optimization, a cardiac output monitor was used to bring the patient to the plateau of the Frank-Starling curve. A pulmonary artery catheter (PAC) with intermittent thermodilution has been used as a clinical standard for cardiac output measurement. However, the use of invasive cardiac output monitoring has decreased, and, consequently, there has been an increased use of minimally invasive monitoring techniques in operating rooms and intensive care units (ICU). The term, “minimally invasive monitoring,” indicates any monitoring technique that is less invasive than, PAC; currently, minimally invasive monitoring techniques include the Vigileo-FloTrac TM system, PiCCO TM monitor, LiDCO TM system, transesophageal echocardiography, and pressure recording analytic method (PRAM). 24 The Vigileo-FloTrac TM system (Edwards LifeSciences, Irvine, CA) requires a proprietary transducer, which is attached to a standard radial or femoral arterial catheter and is connected to the Vigileo TM monitor. The Vigileo-FloTrac TM system requires no external calibration. For estimation of the cardiac output, the standard deviation (SD) of pulse pressure sampled in 20 seconds is related to normal stroke volume (SV) based on the patients’ demographic data (height, weight, age, and gender). Further, it also is correlated with a database that contains information regarding cardiac output measured using a PAC in various clinical settings. Vascular resistance and compliance are estimated by arterial waveform analysis. In the last 5 years, these cardiac output measurement algorithms have been improved repeatedly after conflicting data from early validation studies. Further software improvements have addressed the problem of limited accuracy under low systemic vascular resistance (SVR) states, and recent data have shown improvements in cardiac output measurement under these specific conditions. However, the accuracy of this system after acute SVR changes remains an issue of major concern. Some studies have raised questions about the validity of the data provided by the Vigileo-FloTrac TM system. 25,26 Therefore, the authors performed a review about the reliability of this system. The aim of this review was to provide data regarding the ability of the Vigileo-FloTrac TM system to measure cardiac output and track changes in cardiac output after hemodynamic interventions as well as to assess the reliability of stroke volume variation (SVV) measured by this system.

Guiding Goal-Directed Therapy

Several studies have demonstrated that perioperative hemodynamic optimization (or “goal directed therapy”) using minimally invasive hemodynamic monitoring technologies has the ability to improve postoperative patients’ outcome with lower complication rates, shorter hospital lengths of stay, and lower cost of surgery. This specific concept of goal-directed therapy (GDT) uses perioperative cardiac output monitoring and manipulation of physiologic parameters (dynamic parameters of fluid responsiveness) to guide intravenous fluids and inotropic therapy with the goal of ensuring adequate tissue perfusion. Recently, the evidence related to the implementation of GDT strategies has been considered strong enough to allow for the creation of national recommendations in the UK, in France, and by the European Society of Anaesthesiology. The aims of the programs are to apply best practices to high-risk surgical patients and requires the participation of all clinicians involved in patients’ care. Considering the potential clinical and economic benefits of GDT protocols and the positive recommendations from influential scientific societies, more and more hospitals around the world have become interested in implementing hemodynamic optimization in their departments. This review provides the information about the evolution of hemodynamic monitoring from invasive to the more recent noninvasive devices, and how these devices can be used in the operating rooms through well-defined algorithms of GDT.

Anesthetic management using total intravenous anesthesia with remifentanil in a child with osteogenesis imperfecta.

In patients with osteogenesis imperfecta (OI), general anesthetic management should be carefully implemented in consideration of difficult intubation and the potential risks of cervical or mandibular fracture associated with tracheal intubation, bone fracture during postural changes, and respiratory dysfunction due to thoracic deformity. To prevent temperature elevation, moreover, many reports have recommended anesthetic management using total intravenous anesthesia (TIVA) rather than inhalation anesthetics, which contribute to temperature elevation. In an 8-year-old boy with type II (fatal type) OI (height, 81 cm; body weight, 12.4 kg), we performed general TIVA with remifentanil and propofol, using a laryngeal mask airway for airway management. All possible intra- and postoperative complications were effectively prevented, and the remifentanil requirement was high, as shown by a mean dose of 0.36 μg·kg−1·min−1.

Brain serotonin content regulates the manifestation of tramadol-induced seizures in rats: disparity between tramadol-induced seizure and serotonin syndrome.

Background:Tramadol-induced seizures might be pathologically associated with serotonin syndrome. Here, the authors investigated the relationship between serotonin and the seizure-inducing potential of tramadol. Methods:Two groups of rats received pretreatment to modulate brain levels of serotonin and one group was treated as a sham control (n = 6 per group). Serotonin modulation groups received either para-chlorophenylalanine or benserazide + 5-hydroxytryptophan. Serotonin, dopamine, and histamine levels in the posterior hypothalamus were then measured by microdialysis, while simultaneously infusing tramadol until seizure onset. In another experiment, seizure threshold with tramadol was investigated in rats intracerebroventricularly administered with either a serotonin receptor antagonist (methysergide) or saline (n = 6). Results:Pretreatment significantly affected seizure threshold and serotonin fluctuations. The threshold was lowered in para-chlorophenylalanine group and raised in benserazide + 5-hydroxytryptophan group (The mean ± SEM amount of tramadol needed to induce seizures; sham: 43.1 ± 4.2 mg/kg, para-chlorophenylalanine: 23.2 ± 2.8 mg/kg, benserazide + 5-hydroxytryptophan: 59.4 ± 16.5 mg/kg). Levels of serotonin at baseline, and their augmentation with tramadol infusion, were less in the para-chlorophenylalanine group and greater in the benserazide + 5-hydroxytryptophan group. Furthermore, seizure thresholds were negatively correlated with serotonin levels (correlation coefficient; 0.71, P < 0.01), while intracerebroventricular methysergide lowered the seizure threshold (P < 0.05 vs. saline). Conclusions:The authors determined that serotonin-reduced rats were predisposed to tramadol-induced seizures, and that serotonin concentrations were negatively associated with seizure thresholds. Moreover, serotonin receptor antagonism precipitated seizure manifestation, indicating that tramadol-induced seizures are distinct from serotonin syndrome.