Christoph Bürki

Inhaled nitric oxide versus intravenous vasodilators in severe pulmonary hypertension after cardiac surgery

UNLABELLED Inhaled nitric oxide (iNO) is superior to i.v. vasodilators for treatment of pulmonary hypertension (PH) after cardiac surgery, but iNO is a potentially toxic gas, and patient subsets who benefit from iNO are not yet clearly defined. We administered iNO 40 ppm, prostaglandin E1 (PGE1) 0.1 microg x kg(-1) min(-1), and nitroglycerin (NTG) 3 to 5 microg x kg(-1) min(-1), in a randomized crossover study to 14 adult patients with severe PH after cardiac surgery. iNO, PGE1, and NTG were of similar efficacy in reducing pulmonary vascular resistance (P = 0.003). iNO induced selective pulmonary vasodilation, while PGE1 and NTG had significant concomitant systemic vasodilatory effects. iNO led to an increase in cardiac index (CI) (P = 0.012), and PGE1 increased CI (P = 0.006) and right ventricular (RV) ejection fraction (P = 0.015), while NTG had no effect on CI and RV performance. After study completion, patients continued with PGE1 administration with favorable in-hospital outcome. We conclude that PH per se, even if severe, does not necessarily imply postoperative RV dysfunction, and selective pulmonary vasodilation with iNO may not be superior to PGE1 with regard to CI and RV performance. IMPLICATIONS In a prospective, randomized crossover study of inhaled nitric oxide (iNO) versus IV vasodilators, performed in adult patients with severe pulmonary hypertension but preserved right ventricular function after cardiac surgery, iNO was not superior to IV prostaglandin E1 with regard to cardiac index and right ventricular performance. Considering the potential toxicity of iNO, better definition of patient subsets with a positive benefit/risk ratio is warranted.

Severe Congenital Heart Defects Are Associated with Global Reduction of Neonatal Brain Volumes

OBJECTIVES To determine neonatal global and regional brain volumes in infants with congenital heart disease (CHD) in comparison with healthy controls and to determine brain growth. STUDY DESIGN Prospective cohort study in infants undergoing open-heart surgery for complex CHD. Global and regional volumetric measurements on preoperative cerebral magnetic resonance imaging were manually segmented in children without overt brain lesions. RESULTS Preoperative brain volumetry of 19 patients demonstrates reduction in total and regional brain volumes, without any specific regional predilection compared with 19 healthy control infants (total brain volume reduction: 21%, regional brain volume reduction 8%-28%, all P < .001). CONCLUSIONS Infants with CHD undergoing bypass surgery have smaller brain volumes prior to surgery without a specific regional predilection. This suggests a fetal origin of reduced brain growth.

Pediatric heart transplantation

Pediatric heart transplantation (pHTx) represents a small (14%) but very important and particular part in the field of cardiac transplantation. This treatment has lifelong impact on children. To achieve the best short and especially long-term survival with adequate quality of life, which is of crucial importance for this young patient population, one has to realize and understand the differences with adult HTx. Indication for transplantation, waitlist management including ABO incompatible (ABOi) transplantation and immunosuppression differ. Although young transplant recipients are ultimately likely to be considered for re-transplantation. One has to distinguish between myopathy and complex congenital heart disease (CHD). The differences in anatomy and physiology make the surgical procedure much more complex and create unique challenges. These recipients need a well-organized and educated team with pediatric cardiologists and intensivists, including a high skilled surgeon, which is dedicated to pHTx. Therefore, these types of transplants are best concentrated in specialized centers to achieve promising outcome.

The PediaSat continuous central SvO2 monitoring system does not reliably indicate state or course of central venous oxygenation

Background and objective The present study compares the accuracy of a new continuous venous oxygenation monitoring system (PediaSat Oximetry Catheter) with laboratory blood oximetry in paediatric surgical patients. Methods Children and adolescents undergoing cardiac, orthopaedic or craniofacial surgery with major blood loss were included. A 4.5 Fr two-lumen or 5.5 Fr three-lumen central venous oximetry catheter (SPediaSatcvO2) was inserted preoperatively into the superior vena cava. After in-vivo calibration of the PediaSat system, repeated blood samples were obtained from the distal port of the venous catheter and oximetrically analysed for haemoglobin and central venous oxygen saturation (SCO-OXcvO2). Central venous oxygen saturation values measured by the PediaSat (SPediaSatcvO2) were compared with co-oximetry (SCO-OXcvO2) values from the simultaneously taken blood samples by Bland–Altman and simple regression analyses. Results Overall, 142 data pairs from 27 patients, aged from 0.6 to 19.0 years (median 5.3 years) were analysed. SPediaSatcvO2 and SCO-OXcvO2 values ranged from 57 to 98% and from 57.1 to 95.8%, respectively. Correlation between SPediaSatcvO2 and SCO-OXcvO2 was poor with r2 equal to 0.28 (P < 0.0001). SPediaSatcvO2 overestimated SCO-OXcvO2 (mean bias +2.6%), but limits of agreement (±2 SD of bias) were unacceptably high (−14.4/+19.6%). Sensitivity and specificity of SPediaSatcvO2 to indicate a fall or rise of SCO-OXcvO2 between two subsequent measurements were only 0.42 and 0.24, respectively. Conclusion In paediatric and adolescent patients undergoing major surgery, the PediaSat system did not reliably reflect SCO-OXcvO2 values and cannot replace repeated invasive ScvO2 assessments in the clinically relevant range of ScvO2.

Measurement of Activated Coagulation Time in Children: Evaluation of the Blood-Saving Kaolin i-STAT Activated Coagulation Time Technique in Pediatric Cardiac Anesthesia

OBJECTIVE To compare the activated coagulation times (ACTs) measured with the blood-saving kaolin i-STAT 1 ACT technique (Abbott Point of Care Inc, Princeton, NJ) with ACTs obtained from the widely used ACTR II device (Medtronic, Inc, Minneapolis, MN) in children undergoing cardiac surgery. DESIGN A prospective, observational single-center study. PARTICIPANTS Forty-four pediatric cardiac surgery patients. INTERVENTION Surgery was performed with cardiopulmonary bypass (CPB) necessitating heparinization. METHODS AND MAIN RESULTS ACTs measured on the i-STAT 1 device (2 × 95 μL) were compared with those obtained from the Medtronic ACTR II device (2 × 0.5 mL). Blood samples were drawn before, during, and after heparinization for CPB and paired for statistical analysis. The 2 techniques were compared using simple and multiregression analyses and the Bland-Altman method. In total, 179 intrarater and 142 interrater data pairs were analyzed. The intrarater reliability of the 2 devices was good, with a mean bias and limits of agreement of +2.0 and -55.5/+59.5 seconds for the Medtronic ACTR II and +0.5 and -59.9/+60.9 seconds for the i-STAT 1. An interrater reliability analysis of the mean of simultaneously measured ACT of the Medtronic ACTR II and both i-STAT 1 devices yielded a mean bias of -5.3 seconds and limits of agreement of -210.1/+199.5 seconds. A comparison of the higher of the paired ACT values from both devices showed similar results. After the removal of heparin, the i-STAT 1s ACT values became significantly lower than those measured on the Medtronic ACTR II (p < 0.001). Simple and multiregression analyses revealed that base excess independently influenced the mean bias of the ACT values from the Medtronic ACTR II (p = 0.037) and i-STAT 1 devices (p = 0.036). CONCLUSION The kaolin i-STAT 1 ACT technique agreed well with the Medtronic ACTR II technique during the nonheparinized phase that preceded CPB. The overall agreement between the ACT obtained from the 2 devices was poor. The routine use of i-STAT 1 measured ACT values cannot be recommended as a reliable alternative to the Medtronic ACTR II.

In-vitro evaluation of the PediaSat continuous central venous oxygenation monitoring system

Background and objective In-vitro performance of the PediaSat system for continuous monitoring of central venous oxygen saturation by spectrophotometry has been evaluated. Methods PediaSat continuous fibre-optic oximetry catheters were inserted in a black testing chamber, connected with an extracorporeal circuit and filled with human whole blood. Oxygen inflow into the cardiopulmonary bypass system was varied, and the testing chamber was perfused with blood flow of 1000 ml min−1. Oxygen saturation values measured by PediaSat (SPediaSatO2) were compared with cooximetry (SCO-OXO2) values from simultaneously taken blood samples by Bland–Altman and simple regression analyses. Results Fifty data pairs were obtained. SPediaSatO2 and SCO-OXO2 values ranged between 28–98 and 24.9–99.5%, respectively. Correlation between SPediSatO2 and SCO-OXO2 was high with an r2 value equal to 0.96 (P < 0.0001). Overall, SPediaSatO2 only slightly overestimated SCO-OXO2 (mean bias +2.9%), and limits of agreement (±2 SD of bias) were acceptable (−6.8/+12.6%). Sensitivity and specificity of the first differences of SPediaSatO2 and SCO-OXO2 were 1.0 and 0.92, respectively. Subgroup analysis of SCO-OXO2 values below 70% resulted in an overestimation by SPediaSatO2, with a mean bias of +5.2% and limits of agreement of −4.7 and +15.1%. Conclusion The current version of the PediaSat system does not reliably reflect SCO-OXO2 values below 70%, but it seems to be a useful tool providing an accurate trend of continuous central venous oxygen saturation.

Role of sevoflurane in organ protection during cardiac surgery in children: a randomized controlled trial.

OBJECTIVES The protective effects of volatile anaesthetics against ischaemia-reperfusion injury have been shown in vitro, but clinical studies have yielded variable results. We hypothesized that, in children, sevoflurane provides superior cardioprotection after cardiac surgery on cardiopulmonary bypass (CPB) compared with totally intravenous anaesthesia (TIVA). METHODS In this randomized controlled, single-centre study, 60 children with cyanotic and acyanotic heart defects undergoing elective cardiac surgery under CPB (RACHS-1 1-3) were randomized to sevoflurane or TIVA (midazolam <6 months of age, propofol >6 months of age). The primary end-point was the postoperative peak cardiac troponin I/T (cTnI/T). Perioperative cardiac function (as determined by brain-type natriuretic peptide, echocardiography and postoperative vasopressor/inotrope requirements), short-term clinical outcomes (duration of intubation, intensive care unit and hospital length of stay), postoperative inflammatory profile, and pulmonary, renal and liver function were defined as secondary end-points. Analysis of variance was used for statistical analysis. RESULTS There was no statistically significant difference in postoperative peak troponin values or any of the secondary end-points. In the subgroup of acyanotic patients under 6 months, sevoflurane led to significantly lower postoperative troponin levels compared with midazolam [reduction of 54% (95% confidence interval 29-71%, P = 0.002)], without any differences in secondary outcome parameters. CONCLUSIONS Sevoflurane did not provide superior myocardial protection in our general paediatric cardiac surgical population. In children under 6 months, however, sevoflurane might be beneficial in comparison with midazolam. The conditioning effects of sevoflurane in specific paediatric subgroups need to be further investigated.

Cardiac transplantation in a neonate-First case in Switzerland and European overview

Twenty‐four percent of pediatric heart transplantations (pHTx) are carried out in infants. Neonatal heart transplantation is both rarely performed and challenging. We report on a newborn baby girl suffering from cardiac failure due to a huge tumor (24×52 mm) within the free wall of the left ventricle (LV) and subtotal obstruction of the main left bronchus. Following a surgical tumor resection, a Berlin Heart EXCOR left ventricular assist device was implanted as the bridge to the transplantation. In spite of an organ donor/recipient mismatch of >200%, both heart transplantation and the postoperative course were successful. In addition to this case report, the authors also present data from a survey on performed infant and neonatal transplantations in Western Europe. As neonatal heart transplantation is a rare event in Europe, the authors think it is of crucial importance to share this limited experience. We discuss an alternative strategy—namely, palliative surgical correction using the Fontan pathway. The challenges of donor/recipient weight mismatch and the possibilities of overcoming infant donor organ shortage as a postoperative immunosuppressive regimen are discussed as well.