H. Stopfkuchen

Effects of dobutamine on left ventricular performance in newborns as determined by systolic time intervals

To evaluate the effects of dobutamine on myocardial function in newborns, left ventricular systolic time intervals (STI) — normalized pre-ejection period (PEPI), normalized left ventricular ejection time (LVETI) and pre-ejection period to left ventricular ejection time ratio (PEP/LVET) — were assessed by echocardiography in 18 newborns treated with dobutamine for clinically diagnosed heart failure. Examinations were performed prior to and 30 min after starting dobutamine infusion (7.5 or 10 μg/kg per min). Patients were assigned to two groups according to their PEP/LVET prior to dobutamine administration: group I (n=9) with pre-treatment PEP/LVET ≤ 0.35 and group II (n=9) with pre-treatment PEP/LVET > 0.35. While there was no change of STI in group I, dobutamine infusion resulted in a significant decrease in PEPI (from 102±4.8 to 87.8±4.2; mean ± SEM;P<0.01) and of PEP/LVET (from 0.56±0.05 to 0.45±0.05; mean ±SEM;P<0.01) and in a significant increase of LVETI (from 237.6±5.6 to 253.3±5.2; mean ±SEM;P<0.01) in group II. Heart rate increased significantly in both groups. Left ventricular end-diastolic dimension, also assessed by echocardiography, did not change in the eight studies performed. An increase in mean arterial pressure was found in three out of five newborns of group II and in one out of four patients in group I. It is concluded that dobutamine can improve cardiac performance in newborns with impaired left venfricular function. This effect is probably due to an improvement in myocardial contractility.

Continuous monitoring of mixed venous oxygen saturation in infants after cardiac surgery

Continuous mixed venous oxygen saturation SvO2c was measured in 16 infants immediately after cardiac surgery. A polyurethane 4F, dual channel catheter (Opticath, Modell U440, Oximetrix) with fiberoptic filaments was introduced into the pulmonary artery during cardiothoracic surgery. The catheters were left in place for an average of 67.5 h (range 27 h – 125 h) and there were no catheter-related complications. Correlation between continuous in vivo SvO2 values and in vitro values was satisfactory (r=0.85), whereas a correlation between SvO2c and arterial oxygen saturation (SaO2) was not found (r=0.07). The sampled arterial lactate values were inversely correlated to the simultaneously measured SvO2c, but the corelation coefficient was only r=-0.4. There was an inverse correlation between SvO2c and arteriovenous oxygen content difference (Ca−vDO2c) (r=-0.82), and a marked inverse correlation to the calculated oxygen utilization ratio (r=-0.97). Therefore SvO2c continuously reflects the overall balance between oxygen consumption and delivery, but the use of SvO2 as a predictor of blood lactate levels is unreliable. A further purpose of the present study was to demonstrate the clinical applications and to show the usefulness of SvO2c-monitoring; particularly as a surveillance and early warning system, as a guide for assessing therapy and its relevance in interpreting other monitored parameters. In our opinion continuous SvO2 measurement is a reliable and valuable indicator of cardiopulmonary function in the immediate post-operative period, even in infants with complicated repair of cardiac malformations.

Hemodynamic effects of dobutamine in children with cardiovascular failure.

The effect of dobutamine, a synthetic catecholamine, was studied in 12 patients aged one day to 14 years with low cardiac output syndromes.After initial stabilization of the patients dobutamine was administered by continuous infusion in a dosage of 7.5 or 10 μg/kg/min.Heart rate, cardiac output (using thermodilution technique and/or pulse contour method), mean systemic and mean pulmonary artery pressures were determined before and after the dobutamine infusion. Systemic and pulmonary vascular resistances, cardiac index and stroke volume index were calculated.Cardiac output and cardiac index increased significantly in every patient, whereas the heart rate changed only slightly, suggesting that the increase in cardiac output was mainly due to the alteration of stroke volume. The mean arterial pressure increased significantly, but the mean pulmonary artery pressure was unchanged. No side effects were observed during the dobutamine infusion. Dobutamine is a potent inotropic drug with limited chronotropic and peripheral vascular effects in newborns, infants and chidren.

Physical performance in long-term survivors of acute leukaemia in childhood

Abstract The aim of this study was to assess the physical performance in long-term survivors of acute leukaemia in childhood and to evaluate the effects of anthracycline therapy. Electrocardiography, echocardiography and spiroergometry were carried out on 56 patients aged 9–28 years, of whom 44 patients had been treated with 15–483u2009mg/m2 doxorubicin (or equivalent). Acute leukaemia had been diagnosed 1.5–16 years earlier. Of the patients 75% reached normal maximal oxygen uptake, 69% normal oxygen uptake at the anaerobic threshold and 95% normal maximal work rate. Of the patients 75% achieved adequate values for maximal heart rate and 78% normal blood lactate concentration. No difference was seen between patients treated with and without anthracyclines.nConclusion The results of this study provide little evidence for cardiopulmonary impairment in long-term survivors of ALL. Both the cardiac function, as evaluated by ECG and echocardiography, and the physical performance in spiroergometry are normal in a large number of these patients. Anthracycline treatment does not appear to have a negative effect on these parameters.

Effects of dopamine infusion on plasma catecholamines in preterm and term newborn infants

Newborn infants (21 preterm and 13 term) received dopamine infusions at a low (2.5–3.4 μg/kg per min) and/or high (5–10 μg/kg per min) infusion rate and changes in plasma catecholamines were monitored. The mean baseline values for dopamine, noradrenaline and adrenaline were between 240 and 560, 125 and 144 and 62 and 82 pg/ml, respectively. During low-rate infusion of dopamine, there was a significant increase in plasma dopamine (20–100fold), noradrenaline (three- to five-fold) and adrenaline (threefold). Administration of dopamine at the high rate resulted in an even larger increase in the plasma catecholamines (dopamine, 100–300fold; noradrenaline, seven- to eightfold; adrenaline, four- to sixfold). In a double-log plot, there was a highly significant correlation between the plasma concentrations of dopamine and noradrenaline (r=0.77;P<0.001). In conclusion, infusion of dopamine in term and preterm newborn infants is accompanied by an enhanced sympatho-adrenal tone which may contribute to the cardiovascular effects of dopamine in these patients.

[Limits of the meaningfulness of intensive care medicine : Position paper of the Ethics Section of DIVI].

MedKlin IntensivmedNotfmed2016 ·111:486–492 DOI 10.1007/s00063-016-0202-8 Online publiziert: 25. Juli 2016

Therapy goal modification and therapy limit in intensive care medicine

Aufgabe des Arztes 1 ist es, unter Beachtung des Selbstbestimmungsrechtes des Patienten Leben zu erhalten, Gesundheit zu schützen und wieder herzustellen sowie Leiden zu lindern und Sterbenden bis zum Tod beizustehen. Der Medizin stehen dazu immer mehr und differenziertere Möglichkeiten zur Verfügung. Der Arzt hat im Rahmen seiner professionellen Verantwortung zu entscheiden, welche der vorhandenen Behandlungsmöglichkeiten indiziert sind. Bereits die Alternative, etwas tun zu können oder es zu unterlassen, zwingt in der konkreten Situation dazu, diese Entscheidung zu treffen. Auch wer abwartet, trifft eine Entscheidung. Die ärztliche Verpflichtung zur Lebenserhaltung besteht nicht in jedem Fall. Es können Therapiezieländerung und Therapiebegrenzung geboten sein. Die medizinische Indikation und der Wille des Patienten sind Grundvoraussetzungen bei der Festlegung der Diagnostik und der Therapie. Ärztliche Entscheidungen gründen sich auf medizinisches Wissen, ethische Prinzipien und sind eingebettet in juristische, soziokulturelle und ökonomische Rahmenbedingungen. Zu den wesentlichen ethischen Prinzipien, die zu beachten sind, zählen Menschenwürde, Autonomie, Fürsorge, Nicht-Schaden und Gerechtigkeit. Dieses Positionspapier möchte dem Arzt bei seinen individuell zu verantwortenden Entscheidungen eine Orientierungshilfe bieten. Spezielle ethische Fragen im Zusammenhang mit der pädiatrischen Intensivmedizin und der potenziellen postmortalen Organspende bleiben unberührt.

Evaluation of the Valve Area Underestimation by the Continuity Equation

During the last years, noninvasive determination of the aortic valve area by Doppler echocardiography using the continuity equation became popular. However, a systematic valve area underestimation of about 15% compared to invasive measurements using the Gorlin formula has been reported. The cause therefore is unknown. The purpose of this study was to evaluate whether the valve area underestimation by the Doppler method might be due to differences in the hydrodynamic background of both methods. This comparison is facilitated by the fact that the Gorlin formula is based on the continuity equation. Compared to the continuity equation, there are four changes within the Gorlin formula: (1) the additional use of a discharge coefficient, which leads to valve area overestimation by the factor 1.17; (2) neglect of the pre-stenotic velocity, causing further overestimation by the factor 1.036 (in mild stenosis this factor may be 1.18 and more); (3) the wrong calculation of the mean pressure drop, which leads to a mean change by the factor 0.95, and (4) the incorrect substitution of the height by the pressure drop in the derivation of the Gorlin formula causes underestimation by the factor 0.97. Combining these four factors results in valve area overestimation of the Gorlin formula compared to the continuity equation by the factor 1.12. This explains to a large extent the valve area underestimation by the continuity equation.

Recovery kinetics of heart rate and oxygen uptake in long-term survivors of acute leukemia in childhood

Analysis of the recovery period following physical exercise has gained importance in evaluating cardiopulmonary capacity, not only in athletes but also in patients with proven or suspected heart failure. The purpose of this study was to apply these methods to long-term survivors of acute lymphoblastic leukemia (ALL) in childhood, who are at risk of developing anthracycline-induced cardiomyopathy. Nine children (mean age 12xa0years) and 10 adults (mean age 24xa0years) were included in the study after treatment for childhood ALL. Recovery of oxygen uptake and heart rate following maximal spiroergometric exercise was compared to that in 29 trained and untrained age-matched controls. The change in oxygen uptake (ΔVO2) and heart rate (ΔHR) between maximal effort and 60xa0s of recovery did not differ significantly, either between children after oncological therapy (ΔVO2: 14.95xa0ml/kg, ΔHR: 35xa0bpm) and healthy children (ΔVO2: 15.85xa0ml/kg, ΔHR: 37xa0bpm), or between adult former oncological patients (ΔVO2: 13.1xa0ml/kg, ΔHR: 27xa0bpm) and untrained adults (ΔVO2: 15.7xa0ml/kg, ΔHR: 31xa0bpm). There was, however, a significant difference in ΔVO2 between trained adults (ΔVO2: 24.5xa0ml/kg) and both untrained adult controls (ΔVO2: 15.7xa0ml/kg, pu2009=u20090.004) and adult patients (ΔVO2: 13.1xa0ml/kg, pu2009=u20090.0002). This difference was not detected for heart rate. In conclusion, the recovery period did not reveal a discernible difference in cardiopulmonary capacity between former ALL patients and untrained age-matched controls. We did confirm that heart rate and oxygen uptake recovery serve as indicators of physical fitness.

The effect of nifedipine alone or combined with low dose acetylsalicylic acid on endotoxin-induced pulmonary hypertension in the piglet

Cardiovascular responses to the calcium antagonist nifedipine, alone and combined with low dose acetylsalicylic acid (ASA), were evaluated in a piglet model of endotoxin-induced pulmonary hypertension. All animals were anesthetized, paralyzed and mechanically ventilated. Cardiac output (CO), pulmonary artery pressure (PAP), aortic blood pressure (SAP), pulmonary capillary wedge pressure (PCWP), right strial pressure (RAPM) and arterial blood gases were measured before and after induction of pulmonary hypertension by E. coli endotoxin and after treatment. Results of treated groups were compared to a control group of piglets subjected to the same dose (0.15 μg/kg i.v.) of endotoxin. Control animals responded to a bolus injection of endotoxin within 15 min with an increase in mean PAP by 110%. Pulmonary vascular resistance (PVR) increased by 144%. Mean arterial pressure did not change significantly from baseline values. In animals treated with a single dose of 1 mg/kg ASA prior to endotoxin, the initial pulmonary response was not quantitatively different from control values, whereas ASA 20 mg/kg abolished the pulmonary vascular reaction. The increase of systemic vascular resistance (SVR) produced by endotoxin was aggravated by high dose ASA. In piglets treated with nifedipine (4 μg/kg/min) over 30 min after the application of endotoxin with and without additional infusion of nifedipine 60 min prior to endotoxin the PVR could be attenuated. The combination of nifedipine and low dose ASA showed synergistic effects compared to control. The increase of mean PAP was significantly reduced, the PVR remained in base-line range due to a marked elevation of cardiac output.