M. Filipovic

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.

Different effects of sevoflurane, desflurane, and isoflurane on early and late left ventricular diastolic function in young healthy adults

BACKGROUNDnKnowledge on the effects of volatile anaesthetics on left ventricular (LV) diastolic function in humans in vivo is limited. We tested the hypothesis that sevoflurane, desflurane, and isoflurane do not impair LV diastolic function in young healthy humans.nnnMETHODSnSixty otherwise healthy subjects (aged 18-48 yr) undergoing minor procedures under general anaesthesia were studied. After randomization for the anaesthetic, transthoracic echocardiographic examinations were performed at baseline and under anaesthesia with 1 minimum alveolar concentration (MAC) of the volatile anaesthetics during spontaneous breathing and intermittent positive pressure ventilation (IPPV). Peak early (E) and late (A) diastolic velocities of the mitral annulus were studied as the main echocardiographic indicators of diastolic function.nnnRESULTSnDuring anaesthesia with 1 MAC under spontaneous breathing, E increased with desflurane (P<0.001), was not significantly different with isoflurane (P=0.030), and decreased with sevoflurane (P=0.006). During IPPV, E was similar to baseline with desflurane (P=0.550), insignificantly decreased with isoflurane (P=0.029), and decreased with the sevoflurane group (P<0.001). In contrast, A was similarly reduced in all groups during spontaneous breathing without further changes during IPPV. Haemodynamic changes were comparable in all study groups.nnnCONCLUSIONSnThe findings of this in vivo study indicate that desflurane and isoflurane, and most likely sevoflurane, have no relevant direct negative effect on early diastolic relaxation in young healthy humans. In contrast, all three volatile anaesthetics appear to impair late diastolic LV filling during atrial contraction.

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.

Impact of loss of high-molecular-weight von Willebrand factor multimers on blood loss after aortic valve replacement

BACKGROUNDnSevere aortic stenosis is associated with loss of the largest von Willebrand factor (vWF) multimers, which could affect primary haemostasis. We hypothesized that the altered multimer structure with the loss of the largest multimers increases postoperative bleeding in patients undergoing aortic valve replacement.nnnMETHODSnWe prospectively included 60 subjects with severe aortic stenosis. Before and after aortic valve replacement, vWF antigen, activity, and multimer structure were determined and platelet function was measured by impedance aggregometry. Blood loss from mediastinal drainage and the use of blood and haemostatic products were evaluated perioperatively.nnnRESULTSnBefore operation, the altered multimer structure was present in 48 subjects (80%). Baseline characteristics and laboratory data were similar in all subjects. The median blood loss after 6 h was 250 (105-400) and 145 (85-240) ml in the groups with the altered and normal multimer structures, respectively (P=0.182). After 24 h, the cumulative loss was 495 (270-650) and 375 (310-600) ml in the groups with the altered and normal multimer structures, respectively (P=0.713). Multivariable analysis revealed no significant influence of multimer structure and platelet function on bleeding volumes after 6 and 24 h. After 24 h, there was no obvious difference in vWF antigen, activity, and multimer structure in subjects with and without the altered multimer structure before operation or in subjects with and without perioperative plasma transfusion.nnnCONCLUSIONSnThe altered vWF multimer structure before operation was not associated with increased bleeding after aortic valve replacement. Our findings might be explained by perioperative release of vWF and rapid recovery of the largest vWF multimers.

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.

Intra-operative myocardial ischaemia cannot be detected by analysis of transmitral inflow patterns in patients undergoing off-pump coronary surgery

Background and objective: Transmitral inflow patterns have been used for detection of myocardial ischaemia. However, its diagnostic value has not been tested in anaesthetized and mechanically ventilated patients undergoing coronary artery bypass graft surgery. Methods: Transmitral inflow patterns were studied by transoesophageal Doppler echocardiography in 43 patients undergoing coronary artery bypass graft surgery without cardiopulmonary bypass after opening of the sternum (baseline) and during grafting of the left anterior descending artery. Peak early (E) and peak late (A) transmitral velocities and their ratio (E/A) were recorded. Myocardial ischaemia was defined by standard criteria using two‐dimensional echocardiography and seven‐lead electrocardiogram. Results: Thirty‐one patients (64 ± 8 yr, 9 women) fulfilled the predefined inclusion criteria for analysis. During distal revascularization, 16 patients showed myocardial ischaemia and 15 did not. The use of vasoactive drugs, haemodynamic findings and transmitral inflow patterns were similar in both groups at baseline and during grafting. In the ischaemic group, E was 67.1 ± 13.9 cm s−1 at baseline and 69.5 ± 23.2 cm s−1 during grafting, and the E/A ratios were 1.3 ± 0.3 and 1.4 ± 0.9, respectively. In the non‐ischaemic group, E was 64.0 ± 17.1 cm s−1 at baseline and 60.9 ± 14.8 cm s−1 during grafting, and the E/A ratios were 1.4 ± 0.7 and 1.2 ± 0.3, respectively. Conclusions: Analysis of Doppler findings of transmitral inflow patterns did not allow for detection of myocardial ischaemia during surgical revascularization of the myocardium.

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.

Gastric rupture after bag-mask-ventilation.

A 42 year old woman underwent bronchoscopy with procedural propofol sedation. During the procedure, the patient suffered respiratory arrest, and bag-mask ventilation was initiated. During forced mask ventilation, abdominal distention occurred. Even after correct placement of an endotracheal and a nasogastric tube, high inspiratory pressures persisted. The abdominal CT scan revealed a high amount of intraperitoneal free air. An emergent laparotomy confirmed a stomach rupture. Immediately after opening of the peritoneal cavity, peak ventilatory pressures decreased. In this case forceful bag-mask ventilation led to air insufflation into the stomach, increasing gastric pressure, and consecutive stomach rupture.