Xenon anaesthesia for patients undergoing off-pump coronary artery bypass graft surgery: a prospective randomized controlled pilot trial.

BACKGROUND: Off-pump coronary artery bypass (OPCAB) surgery carries a high risk for haemodynamic instability and perioperative organ injury. Favourable haemodynamic effects and organ-protective properties could render xenon an attractive anaesthetic for OPCAB surgery. The primary aim of this study was to assess whether xenon anaesthesia for OPCAB surgery is non-inferior to sevoflurane anaesthesia with regard to intraoperative vasopressor requirements. METHODS: Forty-two patients undergoing elective OPCAB surgery were enrolled in this prospective, single-blind, randomized controlled pilot trial. Patients were randomized to either xenon (50-60 vol%) or sevoflurane (1.1-1.4 vol%) anaesthesia. Primary outcome was intraoperative noradrenaline requirements necessary to achieve predefined haemodynamic goals. Secondary outcomes included safety variables such as the occurrence of adverse events (intraoperatively and during a 6-month follow-up after surgery) and the perioperative cardiorespiratory and inflammatory profile. RESULTS: Baseline and intraoperative data did not differ between groups. Xenon was non-inferior to sevoflurane, as xenon patients required significantly less noradrenaline intraoperatively to achieve the predefined haemodynamic goals {geometric mean 428 [95% confidence interval (CI) 312, 588] vs 1702 [1267, 2285] µg, P<0.0001}. No differences were found for safety. Significantly more sevoflurane patients developed postoperative delirium (POD) (hazard ratio 4.2, P=0.044). The average arterial pressure was lower in the sevoflurane group {median75 [interquartile range (IQR) 6] vs 72 [4] mmHg, P=0.002}. No differences were found for other haemodynamic parameters, the respiratory profile and the perioperative release of inflammatory cytokines, troponin T, serum protein S-100ß and erythropoietin. CONCLUSIONS: Compared with sevoflurane, xenon anaesthesia allows a significant reduction in vasopressor administration in OPCAB surgery. Moreover, xenon anaesthesia was associated with a lower risk for POD, a finding that has to be confirmed in larger studies. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT01757106) and EudraCT (2012-002316-12).

A randomised controlled trial of intravenous dexamethasone combined with interscalene brachial plexus blockade for shoulder surgery.

We recruited patients scheduled for shoulder rotator cuff repair or subacromial decompression under general anaesthesia and interscalene brachial plexus blockade (30 ml ropivacaine 0.5%). We allocated 240 participants into four groups of 60 that were given pre-operative saline 0.9% or dexamethasone 1.25 mg, 2.5 mg or 10 mg, intravenously. We recorded outcomes for 48 h. The median (IQR [range]) time to first postoperative analgesic request after saline was 12.2 (11.0-14.1 [1.8-48]) h, which was extended by intravenous dexamethasone 2.5 mg and 10 mg to 17.4 (14.9-21.5 [7.2-48]) h, p < 0.0001, and 20.1 (17.2-24.3 [1.3-48]) h, p < 0.0001, respectively, but not by dexamethasone 1.25 mg, 14.0 (12.1-17.7 [2.1-48]) h, p = 0.05. Postoperative analgesia was given sooner after rotator cuff repair than subacromial decompression, hazard ratio (95% CI) 2.2 (1.6-3.0), p < 0.0001, but later in older participants, hazard ratio (95% CI) 0.98 (0.97-0.99) per year, p < 0.0001.

The relationship between superior vena cava diameter and collapsibility and central venous pressure.

The aim of this study was to assess the relationship between superior vena cava (SVC) diameter, collapsibility and central venous pressure (CVP) in cardiac surgical patients. SVC maximum and minimum diameters, plus collapsibility with ventilation, were measured with transoesophageal echocardiography in the mid-oesophageal bicaval view with M-mode. Simultaneously, CVP was measured via the right atrial port of a pulmonary artery catheter. Measurements were possible in 91 out of 92 patients. The median CVP was 10 mmHg with a range of 2 to 19 mmHg. There was a weak, but statistically significant, correlation between CVP and SVC collapsibility index (r=-0.21, P=0.049). There was no statistically significant correlation between maximum SVC diameter and CVP. Maximum SVC diameter was statistically significantly correlated with weight (Pearson's r=0.28, P=0.008). There was no statistically significant correlation between CVP and age or body dimensions. Our findings indicate that SVC diameter and collapsibility are easily measured with transoesophageal echocardiography but do not reliably reflect CVP in anaesthetised cardiac surgical patients.

The utility of transoesophageal echocardiography for estimating right ventricular systolic pressure.

With the reduction in use of the pulmonary artery catheter, alternative methods of pulmonary pressure estimation are required. The use of echocardiographically-derived right ventricular systolic pressure has recently been questioned, but this technique has not been validated in anaesthetised surgical patients with transoesophageal echocardiography. One hundred measurements of right ventricular systolic pressure with transoesophageal echocardiography were compared with the pulmonary artery systolic pressure obtained simultaneously from a pulmonary artery catheter in patients undergoing cardiac surgery. Simultaneous right ventricular systolic pressure and pulmonary artery systolic pressure measurements were possible in all patients, and these measurements were strongly correlated (r = 0.98, p < 0.001), with minimal bias and narrow limits of agreement (approximately -5 to +5 mmHg), across a broad range of pulmonary pressures. Measurement of right ventricular systolic pressure using tranoesophageal echocardiography is readily achievable and closely correlates with pulmonary artery systolic pressure, with minimal bias, in cardiac surgical patients undergoing general anaesthesia and positive pressure mechanical ventilation of the lungs.

Junctional ectopic tachycardia after congenital heart surgery.

PURPOSE: In this literature review, we try to give anesthesiologists a better understanding about Junctional Ectopic Tachycardia (JET), a narrow complex tachycardia that frequently occurs during and after surgery for congenital heart disease. SOURCE: Information was found in the databases of Pubmed, Science Direct, Medline and the Cochrane Library, by using the mesh terms "Tachycardia, Ectopic Junctional", combined with "Diagnosis", "Etiology", "Physiopathology", "Complications" and "Therapy". The publication date of the articles ranged from 1990 to 2012. PRINCIPAL FINDINGS: Risk factors for the development JET are surgery near the AV node, a duration of cardiopulmonary bypass longer than 90 minutes, young age, the use of inotropic drugs and hypomagnesaemia. The diagnosis of Junctional Ectopic Tachycardia can be made on a 12-lead ECG, demonstrating a narrow-complex tachycardia with inverted P-waves and VA dissociation. Adenosine administration and an atrial electrocardiogram can help to confirm the diagnosis. If JET has a minimal impact on the hemodynamic status of the patient, risk factors should be avoided and the adrenergic tonus should be reduced. Hemodynamic unstable JET can be treated by amiodarone, hypothermia and pacing. Extracorporeal membrane oxygenation (ECMO) and radiofrequency or cryoablation are treatment options for life-threatening and resistant JET. CONCLUSION: JET is the most frequent arrhythmia during and after congenital cardiac surgery. The ECG is the only available method to diagnose JET, demonstrating inverted P-waves and VA-dissociation. Amiodarone seems to be the most effective treatment option, because it can restore sinus rhythm and reduces the JET rate.

I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a single-shot interscalene block with ropivacaine for shoulder surgery: a prospective, randomized, placebo-controlled study.

BACKGROUND: Interscalene brachial plexus block (ISB) provides excellent, but time-limited analgesia. Dexamethasone added to local anaesthetics prolongs the duration of a single-shot ISB. However, systemic glucocorticoids also improve postoperative analgesia. The hypothesis was tested that perineural and i.v. dexamethasone would have an equivalent effect on prolonging analgesic duration of an ISB. METHODS: We performed a prospective, double blind, randomized, placebo-controlled study. Patients presenting for arthroscopic shoulder surgery with an ISB were randomized into three groups: ropivacaine 0.5% (R); ropivacaine 0.5% and dexamethasone 10 mg (RD); and ropivacaine 0.5% with i.v. dexamethasone 10 mg (RDiv). The primary outcome was the duration of analgesia, defined as the time between performance of the block and the first analgesic request. Standard hypothesis tests (t-test, Mann-Whitney U-test) were used to compare treatment groups. The primary outcome was analysed by Kaplan-Meier survival analysis with a log-rank test and Cox's proportional hazards regression. RESULTS: One hundred and fifty patients were included after obtaining ethical committee approval and patient informed consent. The median time of a sensory block was equivalent for perineural and i.v. dexamethasone: 1405 min (IQR 1015-1710) and 1275 min (IQR 1095-2035) for RD and RDiv, respectively. There was a significant difference between the ropivacaine group: 757 min (IQR 635-910) and the dexamethasone groups (P<0.0001). CONCLUSIONS: I.V. dexamethasone is equivalent to perineural dexamethasone in prolonging the analgesic duration of a single-shot ISB with ropivacaine. As dexamethasone is not licensed for perineural use, clinicians should consider i.v. administration of dexamethasone to achieve an increased duration of ISB.

Sickle cell anaemia and the consequences on the anaesthetic management of cardiac surgery.

A review of the available literature on genetics and pathophysiology of Sickle Cell Anaemia was performed with special emphasis on the intraoperative management during cardiac surgery. Hypoxia, acidosis and hypothermia have been identified as independent sickling provoking factors. Although no official guidelines on transfusion for Sickle Cell patients have been published, useful directives on preoperative transfusion could be derived from available data. Additionally, we bundled and reviewed the published expertise in the management of cardiopulmonary bypass and the necessity of hypothermia during cardiac surgery in Sickle Cell patients. Our conclusion is that the available data in case reports and case series on cardiac surgery in case of Sickle Cell Anaemia suggest a necessary preoperative or on bypass blood transfusion to guarantee an uncomplicated course of cardiopulmonary bypass and hypothermia.

Differential effects of lumbar and thoracic epidural anaesthesia on the haemodynamic response to acute right ventricular pressure overload.

BACKGROUND: The safety of epidural anaesthesia in patients at risk for right ventricular pressure overload remains controversial. We compared the haemodynamic effects of vascular and cardiac autonomic nerve block, induced by selective lumbar (LEA) and high thoracic epidural anaesthesia (TEA), respectively, in an animal model subjected to controlled acute right ventricular pressure overload. METHODS: Eighteen pigs were instrumented with epidural catheters at the thoracic (T) and lumbar (L) level and received separate injections at T2 (1 ml) and L3 (4 ml) with saline (s) or bupivacaine 0.5% (b). Three groups of six animals were studied: (i) a control group (Ls+Ts), (ii) LEA group (Lb+Ts), and (iii) TEA group (Ls+Tb). Haemodynamic measurements including biventricular pressure-volumetry were performed. Right ventricular afterload was then increased by inflating a pulmonary artery (PA) balloon. Measurements were repeated after 30 min of sustained right ventricular afterload increase. RESULTS: LEA decreased systemic vascular resistance (SVR) and did not affect ventricular function. TEA had minor effects on SVR but decreased left ventricular contractility while baseline right ventricular function was not affected. Control and LEA-treated animals responded similarly to a PA balloon occlusion with an increase in right ventricular contractility and heart rate. Animals pretreated with a TEA did not show this positive inotropic response and developed low cardiac output in the presence of right ventricular pressure overload. CONCLUSIONS: In contrast to LEA, TEA reduced the haemodynamic tolerance to PA balloon occlusion by inhibiting the right ventricular positive inotropic response to acute pressure overload.

In vitro, in vivo and numerical assessment of the working principle of the truCCOMS continuous cardiac output catheter system.

The truCCOMS cardiac output monitor system provides a continuous and instantaneous measurement of cardiac output, derived from the amount of energy required for heating a filament to maintain a fixed 2 degrees C blood temperature difference between two thermistors located distally on a pulmonary artery catheter. Clinical studies, however, reported relatively poor accuracy of the cardiac output estimation, possibly due to linearly assumed power-cardiac output relationship used for calibration of the catheters. We experimentally studied the shape of the truCCOMS calibration relationship (i) in a hydraulic bench model of the right heart and (ii) in vivo intact animal model. The results showed a nonlinear relationship between the power input into the heating element and the cardiac output; which could satisfactorily be described with an exponential relationship. Comparison of the performance of the same catheters in vitro and in vivo showed that the in vitro determined calibration relationship should not be used for in vivo measurements. Finally, we also simulated the working principle of the catheter using a simplified numerical model of the blood flow and heat transfer around the catheter. The computed results also suggested a pronounced nonlinear relationship between power and cardiac output in pulsatile conditions. We conclude that the observed over- and underestimation of high- and low flows, respectively, by the current truCCOMS system is likely to arise from its linear calibration relationship. An appropriate calibration scheme accounting for the intrinsic nonlinear power-cardiac output relationship and the difference between in vitro and in vivo conditions should improve the clinical performance of the system.

Echocardiographic assessment of left ventricular untwist rate: comparison of tissue Doppler and speckle tracking methodologies.

AIMS: The study was designed to test the influence of the temporal resolution, at which tissue Doppler imaging (TDI) and speckle tracking imaging (STI) operate, on the accurate assessment of left ventricular (LV) untwist rate (UR). METHODS AND RESULTS: Echo imaging and invasive LV pressure measurements were performed during right atrial (RA) pacing and dobutamine challenge in eight pigs. LV torsion and torsional rate profiles were analysed from grey scale and tissue Doppler data (apical and basal short axis) at frame rates of 82 +/- 17 and 183 +/- 14 Hz, respectively. Temporal subsampling of TDI data sets was performed at 82 +/- 6 Hz in order to mimic the mean temporal resolution of STI and the LV torsional curves were again extracted. At rest, LV UR values were comparable for both imaging techniques. However, during dobutamine stimulation, TDI estimated peak UR was predominantly higher than UR measured by STI (-112.1 +/- 64.5 degrees /s vs. -75.5 +/- 31.4 degrees /s, P < 0.05). The similarity of LV UR measurements with respect to the STI/TDI data was examined by a Bland-Altman analysis. CONCLUSION: Although both methods regarding LV UR correlated well, these methods cannot be interchanged. STI showed a bias to underestimate UR at high values.

Load-sensitivity of regional tissue deformation in the right ventricle: isovolumic versus ejection-phase indices of contractility.

OBJECTIVE: Doppler myocardial imaging is increasingly being used to evaluate regional and global cardiac function. Quantitative measurements of tissue deformation obtained during ejection as well as isovolumic contraction have been proposed as new indices of contractility; however, their load-sensitivity remains a matter of controversy. Maximum strain rate (SR(max)) and isovolumic strain acceleration (ISA(max)) were compared with regard to sensitivity for inotropic state, heart rate and loading conditions in the right ventricle (RV), using pressure-volume analysis as the reference method. DESIGN: Prospective animal study. SETTING: University hospital laboratory. INTERVENTIONS: RV contractility was measured at baseline, after inotropic modulation with esmolol and dobutamine, at different atrial pacing rates and during controlled alterations of RV preload and afterload. MAIN OUTCOME MEASURES: RV contractility was assessed with the slope (Mw) of preload recruitable stroke work and longitudinal SR(max) and ISA(max). RESULTS: SR(max) and ISA(max) reflected the drug-induced changes in contractility, while only ISA(max) increased with higher pacing rates. Acute lowering of RV preload did not affect either of the indices studied. In contrast, an increase in RV afterload consistently decreased SR(max) (from 1.05 (SD 0.41) to 0.73 (SD 0.26) s(-1),p = 0.03) but had variable effects on ISA(max) and Mw. However, a significant correlation was found between proportional changes in ISA(max) and Mw during high-afterload conditions (r2 = 0.89, p = 0.005). CONCLUSIONS: Both SR(max) and ISA(max) reflected changes in RV contractility. ISA(max) was less sensitive to changes in RV afterload than SR(max) and may therefore be a more robust index of global RV contractility.

Accuracy of cardiac output measurements with pulse contour analysis (PulseCO) and Doppler echocardiography during off-pump coronary artery bypass grafting.

BACKGROUND AND OBJECTIVE: During off-pump coronary bypass grafting, surgical manipulation and dislocation of the heart may cause cardiovascular instability. Monitoring of cardiac output facilitates intraoperative haemodynamic management but pulmonary artery catheters are often considered too invasive. Pulse contour analysis and transoesophageal echocardiography could serve as alternatives, but there is controversy about their accuracies. We validated pulse contour analysis using a standard radial arterial catheter (PulseCO) and aortic Doppler flowmetry with transoesophageal echocardiography in patients undergoing off-pump coronary bypass surgery. Pulmonary arterial thermodilution served as the reference technique. METHODS: In 20 patients undergoing off-pump coronary bypass, cardiac output was measured with bolus thermodilution (COTD), pulse contour analysis (COPC), and transoesophageal echocardiography (COecho) at fixed time intervals during the procedure. Data were compared using linear regression and Bland-Altman analysis. At the end of the procedure, dobutamine was infused at a rate of 2.5 microg kg(-1) min(-1) in six patients to study the agreement between methods in quantifying changes in cardiac output. RESULTS: Comparison between COPC and COTD showed a bias +/- limits of agreement of -0.03 +/- 1.30 L min(-1) (mean error 29%). Doppler echocardiography was not always feasible when the heart was displaced from the oesophagus and had lower accuracy: bias +/- limits of agreement vs. COTD was 0.45 +/- 1.93 (mean error 43%). Increases in cardiac output induced by dobutamine were well quantified both by pulse contour analysis (COPC = 0.76 x COTD + 0.58; r(2) = 0.65) and Doppler, although the latter tended to overestimate these changes (COecho = 1.58 x COTD - 0.13; r(2) = 0.53). CONCLUSIONS: Calibrated pulse contour analysis using the PulseCO system is an acceptable technique to measure cardiac output non-invasively in off-pump coronary bypass patients. Doppler echocardiography performs less well and is not always feasible with transoesophageal echocardiography when the heart is displaced.

Patient-controlled epidural analgesia following combined spinal-epidural analgesia in labour: the effects of adding a continuous epidural infusion.

Patient-controlled epidural analgesia (PCEA) is used to maintain epidural analgesia following initial intrathecal analgesia. This trial investigated whether a continuous background infusion with PCEA provides superior analgesia to PCEA alone among patients who received combined spinal-epidural (CSE) analgesia during labour Eighty parturients were randomized to either PCEA alone (PCEA) or PCEA with a background infusion of ropivacaine 0.15% with sufentanil 0.75 microg/ml at 2 ml/h (PCEA + CEI). PCEA settings were a bolus of 4 ml of the same analgesic solution with a lockout interval of 15 minutes. Significantly more patients in the PCEA group required at least one anaesthetist intervention for breakthrough pain (27 [71%] vs 10 [25%] in the PCEA + CEI group, P<0.05). Consumption of local anaesthetic (excluding manually administered boluses) was similar between the groups. If anaesthetist-administered boluses were included, more local anaesthetic was consumed by the PCEA group (47.1 +/- 19.4 mg vs 35.6 +/- 12.0 mg in the PCEA + CEI group, P<0.05). We conclude that PCEA with a background infusion provides effective analgesia with less anaesthetist workload and reduced local anaesthetic consumption as compared with PCEA without a background infusion.

Remifentanil for foetal immobilisation and maternal sedation during endoscopic treatment of twin-to-twin transfusion syndrome : a preliminary dose-finding study.

Twin to twin transfusion syndrome (TTTS) affects 10 to 15% of monochorionic twin pregnancies. Untreated, perinatal loss exceeds 80%, of which survivors have a great risk for long-term neurological disorders as psychomotor retardation or cerebral palsy. TTTS can be treated using foetoscopy and selective ablation of the twin-to-twin blood vessels under local or regional anaesthesia. However, local or regional anaesthesia does not always result in excellent maternal comfort, nor does it provide foetal immobilisation, necessary for optimal surgical conditions. Using a continuous infusion rate of remifentanil 0.1 microg/kg/min, perfect foetal immobilisation and excellent maternal sedation was achieved. Only mild respiratory acidosis was observed as a result of mild respiratory depression. In no mother apnoe occurred. All haemodynamic parameters, both foetal and maternal, remained stable during the procedure. Maternal sedation, respiratory depression and foetal immobilisation were quickly reversible following cessation of the remifentanil infusion.

Management of fetal pain during invasive fetal procedures. A review.

In recent years, fetal stress and analgesia draw more and more attention. Evidence that fetuses show a significant endocrinological and hemodynamical response to invasive stimuli, and that these responses can be blocked by analgesia, suggests that fetuses experience a stress response, even if this does not signify they experience "pain". Moreover, it is becoming increasingly clear that experiences of pain of a fetus will be "remembered" by the developing nervous system, perhaps for the entire life of the individual, which can probably lead to abnormal behavioural patterns or altered nociception. But up to now, the entire mechanism of fetal stress response and the optimal analgesic drug, dose and route of administration is not so clear.