D. Bolliger

The accuracy of non-invasive carbon dioxide monitoring: A clinical evaluation of two transcutaneous systems

We determined the accuracy of two transcutaneous carbon dioxide monitoring systems (SenTec Digital Monitor with V‐Sign Sensor and TOSCA 500 with TOSCA Sensor 92) for the measurement of single values and trends in the arterial partial pressure of carbon dioxide in 122 adult patients during major surgery and in 50 adult patients in the intensive care unit. One or several paired measurements were performed in each patient. The first measurement was used to determine the accuracy of a single value of transcutaneous carbon dioxide; the difference between the first and the last measurements was used to analyse the accuracy and to track trends. We defined a 95% limit of agreement of ≤1u2003kPa as being clinically useful. There was insufficient agreement between transcutaneous carbon dioxide partial pressure values derived from the two systems and arterial carbon dioxide values for both single values and trends as defined by our suggested limit of agreement. We conclude that these systems cannot replace conventional blood gas analysis in the clinical setting studied.

Troponin T and B-Type Natriuretic Peptide After On-Pump Cardiac Surgery Prognostic Impact on 12-Month Mortality and Major Cardiac Events After Adjustment for Postoperative Complications

Background— The independent predictive value of troponin T (TNT) after on-pump cardiac surgery was established in several studies. However, adjustment was limited to preoperative risk factors without considering perioperative complications. Data on the prognostic value of postoperative B-type natriuretic peptide (BNP) are scarce. Our aim was to assess the independent value of TNT and BNP to predict 12-month outcome after cardiac surgery with adjustment for preoperative risk estimates and postoperative complications and to report risk stratification gains when considering the European System for Cardiac Operative Risk Evaluation (EuroSCORE) combined with postoperative biomarkers. Methods and Results— This prospective cohort study included consecutive patients undergoing on-pump cardiac surgery between 2007 and 2010. We evaluated postoperative TNT and BNP, the EuroSCORE, and postoperative complications as predictors of adverse events using Cox regression. The primary end point was death or major adverse cardiac events within 1 year after surgery. We calculated the net reclassification index of TNT and BNP in addition to the EuroSCORE. We enrolled 1559 patients, of whom 176 (11.3%) experienced an event. The adjusted hazard ratio of TNT >0.8 &mgr;g/L was 2.13 (95% confidence interval, 1.47–3.15) and of BNP >790 ng/L was 2.44 (95% confidence interval, 1.65–3.62). The net reclassification index of the addition of TNT and BNP to the EuroSCORE was 0.276 (95% confidence interval, 0.195–0.348). Conclusions— Postoperative TNT and BNP are strong predictors of 1-year events after on-pump cardiac surgery independent of preoperative risk factors and postoperative complications. Updating the preoperative EuroSCORE risk with postoperative TNT and BNP after surgery allows for improved prediction of 1-year death or major adverse cardiac events.

Perioperative administration of fibrinogen does not increase adverse cardiac and thromboembolic events after cardiac surgery

BACKGROUNDnAlthough infusion of fibrinogen concentrate is increasingly used in bleeding patients after cardiac surgery, safety data are scarce. We aimed to evaluate the effect of perioperative administration of fibrinogen concentrate on postoperative morbidity and mortality in patients undergoing cardiac surgery.nnnMETHODSnDuring a 2 yr study period, 991 patients underwent cardiac surgery at a single university centre and were eligible for propensity score (PS) matching. We matched 190 patients with perioperative infusion of fibrinogen concentrate (median dose 2 g) with 190 controls without fibrinogen administration. After PS matching, crude outcome was analysed. Further, a multivariate logistic regression including additional risk factors for adverse outcome was performed. The primary endpoint was a composite of mortality and the occurrence of major cardiac and thromboembolic events within 1 yr. Secondary outcomes included mortality after 30 days and 1 yr and the composite of mortality and adverse events after 30 days.nnnRESULTSnThe administration of fibrinogen concentrate was not associated with an increased risk for mortality and thromboembolic or cardiac events within 1 yr after cardiac surgery [unadjusted hazard ratio (HR) 0.91; 95% confidence interval (CI) 0.55-1.49; P=0.697]. When using multivariate logistic regression model, the HR for adverse outcome in patients with administration of fibrinogen concentrate was 0.57 (95% CI 0.25-1.17; P=0.101). Similarly, the administration of fibrinogen concentrate did not adversely affect the secondary outcomes when applying unadjusted and multivariate regression analyses.nnnCONCLUSIONSnOur study strongly suggests that the administration of fibrinogen concentrates at low dose is not associated with thromboembolic complications or adverse outcomes after cardiac surgery.

Intra-operative assessment of pulmonary artery pressure by transoesophageal echocardiography†

The clinical value of the estimation of systolic pulmonary artery pressure, based on Doppler assessment of peak tricuspid regurgitant velocity using transoesophageal echocardiography, is unclear. We studied 109 patients to evaluate the feasibility of obtaining adequate Doppler recordings, and compared Doppler estimates with values measured using a pulmonary artery catheter in a subset of 33 patients. Tricuspid regurgitation was evaluated at the mid‐oesophageal level at 0–120° using Doppler echocardiography. A Doppler signal was defined as adequate if there was a ≤ 20° alignment and a full envelope. Doppler estimates of systolic pulmonary artery pressure within 10 mmHg and 15% of the value recorded with the pulmonary artery catheter were considered to be in sufficient agreement. Adequate Doppler signals were obtained in 64/109 (59%) patients before and 54/103 (52%) after surgery. Doppler estimates by transoesophageal echocardiography were within 10 mmHg and 15% of values recorded with the pulmonary artery catheter in 28/33 (75%) patients and 22/31 (55%) patients, respectively. In 7 (21%) patients, the echocardiographic Doppler measurement exceeded the measured systolic pulmonary artery pressure by more than 30%. Our study indicates that estimation of the systolic pulmonary artery pressure using transoesophageal Doppler echocardiography is not a reliable and clinically useful method in anaesthetised patients undergoing mechanical ventilation.

Remifentanil does not impair left ventricular systolic and diastolic function in young healthy patients

BACKGROUNDnExperimental studies and investigations in patients with cardiac diseases suggest that opioids at clinical concentrations have no important direct effect on myocardial relaxation and contractility. In vivo data on the effect of remifentanil on myocardial function in humans are scarce. This study aimed to investigate the effects of remifentanil on left ventricular (LV) function in young healthy humans by transthoracic echocardiography (TTE). We hypothesized that remifentanil does not impair systolic, diastolic LV function, or both.nnnMETHODSnTwelve individuals (aged 18-48 yr) without any history or signs of cardiovascular disease and undergoing minor surgical procedures under general anaesthesia were studied. Echocardiographic examinations were performed in the spontaneously breathing subjects before (baseline) and during administration of remifentanil at a target effect-site concentration of 2 ng ml(-1) by target-controlled infusion. Analysis of systolic function focused on fractional area change (FAC). Analysis of diastolic function focused on peak early diastolic velocity of the mitral annulus (e) and on transmitral peak flow velocity (E).nnnRESULTSnRemifentanil infusion at a target concentration of 2 ng ml(-1) did not affect heart rate or arterial pressure. There was no evidence of systolic or diastolic dysfunction during remifentanil infusion, as the echocardiographic measure of systolic function (FAC) was similar to baseline, and measures of diastolic function remained unchanged (e) or improved slightly (E).nnnCONCLUSIONnContinuous infusion of remifentanil in a clinically relevant concentration did not affect systolic and diastolic LV function in young healthy subjects during spontaneous breathing as indicated by TTE.

Randomized clinical trial of moxonidine in patients undergoing major vascular surgery.

Myocardial ischaemia is the leading cause of perioperative morbidity and mortality after surgery in patients with coronary artery disease. The aim of this study was to evaluate the effects of moxonidine, a centrally acting sympatholytic agent, on perioperative myocardial ischaemia and 1‐year mortality in patients undergoing major vascular surgery.

The influence of pre-admission hypoglycaemic therapy on cardiac morbidity and mortality in type 2 diabetic patients undergoing major non-cardiac surgery: a prospective observational study*

It remains unclear whether type 2 diabetics treated with either insulin or oral hypoglycaemic agents have the same incidence of cardiac morbidity and mortality after major non‐cardiac surgery. We prospectively studied 360 type 2 diabetic patients undergoing major non‐cardiac surgery of which 105 were treated with insulin only, 171 were treated with oral hypoglycaemics only and 84 were treated with a combination of insulin and oral hypoglycaemics. All‐cause mortality after 30u2003days and after 12u2003months was highest in the insulin (10% and 26%) and lowest in the oral hypoglycaemics group (2% and 13%; p = 0.02 and 0.007, respectively). Insulin treatment was independently associated with increased mortality after 30u2003days (hazard ratio 3.93; 95% CI 1.22–12.64; pu2003=u20030.022) and 12u2003months (hazard ratio 2.03; 95% CI 1.16–3.58; pu2003=u20030.014) after multivariate adjustment for age, sex and the revised cardiac risk index (insulin treatment excluded). The increased mortality in insulin‐treated diabetic patients may be due to a more progressive disease state in these patients rather than the treatment modality itself.

Volatile anaesthetics and positive pressure ventilation reduce left atrial performance: a transthoracic echocardiographic study in young healthy adults

BACKGROUNDnAnimal and in vitro studies suggest that volatile anaesthetics affect left atrial (LA) performance. We hypothesized that human LA pump function and dimensions are altered by volatile anaesthetics in vivo.nnnMETHODSnWe performed transthoracic echocardiographic (TTE) measurements in 59 healthy subjects (aged 18-48 yr) undergoing minor surgery under general anaesthesia. The unpremedicated patients were randomly assigned to anaesthesia with sevoflurane, desflurane, or isoflurane. TTE examinations were performed at baseline and after induction of anaesthesia and upon placement of a laryngeal mask during spontaneous breathing. After changing to intermittent positive pressure ventilation (IPPV), an additional TTE was performed. The study focused on the velocity-time integral of late peak transmitral inflow velocity (AVTI) and maximum LA volume.nnnRESULTSnWe found no evidence for relevant differences in the effects of the three volatile anaesthetics. AVTI decreased significantly from 4.1 (1.2) cm at baseline to 3.2 (1.1) cm during spontaneous breathing of 1 minimum alveolar concentration of volatile anaesthetics. AVTI decreased further to 2.8 (1.0) cm after changing to IPPV. The maximum LA volume was 45.4 (18.6) cm(3) at baseline and remained unchanged during spontaneous breathing but decreased to 34.5 (16.7) cm(3) during IPPV. Other parameters of LA pump function and dimensions decreased similarly.nnnCONCLUSIONSnVolatile anaesthetics reduced active LA pump function in humans in vivo. Addition of IPPV decreased LA dimensions and further reduced LA pump function. Effects in vivo were less pronounced than previously found in in vitro and animal studies. Further studies are warranted to evaluate the clinical implications of these findings.nnnCLINICAL TRIAL REGISTRATIONnNCT0024451.