Gunther Weitz

Endotoxemia causes central downregulation of sympathetic vasomotor tone in healthy humans

Experimental endotoxemia as a model of the initial septic response affects the autonomic nervous system with profound cardiovascular sequelae. Whether the postsynaptic sympathoneural activity to the muscle vascular bed is altered in the early septic phase remains to be determined. The present study aimed to elucidate the early effects of LPS on muscle sympathetic nerve activity (MSNA) and cardiovascular regulation in healthy humans. Young, healthy volunteers randomly received either an LPS bolus (4 ng/kg body wt, n = 11) or placebo (saline; n = 7). Experimental baroreflex assessment (baseline measurements followed by infusion of vasoactive drugs nitroprusside/phenylephrine) was done prior to and 90 min following LPS or placebo challenge. MSNA, heart rate, blood pressure, and blood levels of catecholamines, TNF-alpha and IL-6 were measured sequentially. Endotoxin but not placebo-induced flu-like symptoms and elevated cytokine levels. In contrast to placebo, LPS significantly suppressed MSNA burst frequency 90 min after injection [mean +/- SE: 12.1 +/- 2.9 vs. 27.5 +/- 3.3 burst/min (post- vs. pre-LPS); P < 0.005] but increased heart rate [78.4 +/- 3.1 vs. 60.6 +/- 2.0 beats/min (post- vs. pre-LPS); P < 0.001]. Baseline blood pressure was not altered, but baroreflex testing demonstrated a blunted MSNA response and uncoupling of heart rate modulation to blood pressure changes in the endotoxin group. We conclude that endotoxin challenge in healthy humans has rapid suppressive effects on postsynaptic sympathetic nerve activity to the muscle vascular bed and alters baroreflex function which may contribute to the untoward cardiovascular effects of sepsis.

Automated continuous chest compression for in-hospital cardiopulmonary resuscitation of patients with pulseless electrical activity: A report of five cases

Of patients with in-hospital cardiac arrest, those with pulseless electrical activity (PEA) have the worst outcome. Especially in these patients effective chest compressions according to the guidelines may be the key strategy to improve survival. Recently, a novel automatic mechanical chest compression device (LUCAS-CPR) has been shown to ensure effective continuous compressions without interruption during transport, diagnostic procedures and in the catheter laboratory, and may thus significantly improve outcome after resuscitation of in-hospital cardiac arrest. We report here on the first five well documented cases of in-hospital resuscitation of PEA using the LUCAS-CPR compression device.

Continuous mechanical chest compression during in-hospital cardiopulmonary resuscitation of patients with pulseless electrical activity

UNLABELLED Survival after in-hospital pulseless electrical activity (PEA) cardiac arrest is poor and has not changed during the last 10 years. Effective chest compressions may improve survival after PEA. We investigated whether a mechanical device (LUCAS™-CPR) can ensure chest compressions during cardiac arrest according to guidelines and without interruption during transport, diagnostic procedures and in the catheter laboratory. METHODS We studied mechanical chest compression in 28 patients with PEA (pulmonary embolism (PE) n=14; cardiogenic shock/acute myocardial infarction; n=9; severe hyperkalemia; n=2; sustained ventricular arrhythmias/electrical storm; n=3) in a university hospital setting. RESULTS During or immediately after CPR, 21 patients underwent coronary angiography and or pulmonary angiography. Successful return of a spontaneous circulation (ROSC) was achieved in 27 out of the 28 patients. Ten patients died within the first hour and three patients died within 24h after CPR. A total of 14 patients survived and were discharged from hospital (13 without significant neurological deficit). Interestingly, six patients with PE did not have thrombolytic therapy due to contraindications. CT-angiography findings in these patients showed fragmentation of the thrombus suggesting thrombus breakdown as an additional effect of mechanical chest compressions. No patients exhibited any life-threatening device-related complications. CONCLUSION Continuous chest compression with an automatic mechanical device is feasible, safe, and might improve outcomes after in-hospital-resuscitation of PEA. Patients with PE may benefit from effective continuous chest compression, probably due to thrombus fragmentation and increased pulmonary artery blood flow.

Modulation of Ventricular Repolarization in Patients with Transient Left Ventricular Apical Ballooning: A Case Control Study

Objective: Even though diffuse T wave inversion and prolongation of the QT interval in the surface electrocardiogram (ECG) have been consistently reported in patients with transient stress‐induced left ventricular apical ballooning (AB), ventricular repolarization has not yet been systematically investigated in this clinical entity.

Changes in Heart Rate, Heart Rate Variability, and Heart Rate Turbulence during Evolving Reperfused Myocardial Infarction

Depressed cardiac parasympathetic activity is associated with electrical instability and adverse outcomes after myocardial infarction (MI). Heart rate turbulence (HRT), reflecting reflex vagal activity, and heart rate variability (HRV), reflecting tonic autonomic variations are both reduced in the subacute phase of MI. However, the evolution of these components of cardiac autonomic control between subacute and chronic phase of MI has not been defined. We prospectively studied 100 consecutive patients with a recent first MI with ST‐segment elevation, who underwent successful direct percutaneous coronary interventions. Beta‐adrenergic blockers and angiotensin‐converting enzyme (ACE) inhibitors were administered according to the state‐of‐the‐art medical practice guidelines. HRT and HRV were measured from 24‐hour ambulatory electrocardiographic recordings 10 days and 12 months after the index MI. There was no significant difference in mean RR interval between the subacute and chronic phase of MI (875 ± 145 versus 859 ± 122 ms). Indices of HRV increased significantly during the observation period (SDNN: from 88.8 ± 26.8 to 116.0 ± 35.7 ms, P < 0.001; SDNNi: from 37.9 ± 15.9 to 46.0 ± 16.3 ms, P < 0.001; SDANN: from 79.6 ± 34.7 to 105.6 ± 35.4 ms, P < 0.001). In contrast, there were no significant changes in indices of HRT (turbulence onset: from −0.008 ± 0.022 to −0.012 ± 0.025%; turbulence slope: from 7.78 ± 5.9 to 8.06 ± 6.8 ms/beat). In contrast to reflex autonomic activity, there was a significant recovery of tonic autonomic activity within 12 months after MI. These different patterns of recovery of reflex versus tonic cardiac autonomic control after MI need to be considered when risk stratifying post‐MI patients.

Question-writing as a learning tool for students – outcomes from curricular exams

BackgroundWriting exam questions can be a valuable learning tool. We asked students to construct multiple choice questions for curricular exams in Internal Medicine. The questions for the particular exams were chosen from a pool of at least 300 student-written questions. The uncorrected pool was accessible to all students. We studied the influence of this approach on the students’ learning habits and their test results. We hypothesized that creating a pool of their own questions for the exams could encourage students to discuss the learning material.MethodsAll students had to pass 4 exams in 7 fields of Internal Medicine. Three exams were comprised of 20 questions, and we applied the new method in one of these exams. The fourth exam was comprised of 30 questions, 15 of which were chosen from a students’ pool. After all exams had been completed we asked the students to fill in a web-based questionnaire on their learning habits and their views on the new approach. The test-results were compared to the results of the lecturers’ questions that defined high and low performing students.ResultsA total of 102 students completed all four exams in a row, 68 of whom filled in the questionnaire. Low performing students achieved significantly better results in the students’ questions. There was no difference in the number of constructed questions between both groups of students. The new method did not promote group work significantly. However, high performing students stated a stronger wish to be rewarded by good performance.ConclusionsCreating a curricular exam by choosing questions from a pool constructed by students did not influence the learning habits significantly and favored low performing students. Since the high performing students sought to be rewarded for their efforts, we do not consider the approach applied in our study to be appropriate.

Detrimental effect of high volume fluid administration in acute pancreatitis - a retrospective analysis of 391 patients.

BACKGROUND Early fluid resuscitation is recommended for the therapy of acute pancreatitis in order to prevent complications. There are, however, no convincing data supporting this approach. METHODS We reviewed 391 consecutive cases of confirmed acute pancreatitis. Admitting physicians had been advised to administer an aggressive fluid resuscitation in the early phase of disease, if possible. We tested whether disease severity according to the revised Atlanta Classification, local complications, and maximum C-reactive protein levels were predictable by the initial volume therapy in logistic and linear regression models, respectively. We also determined which parameters on admission encouraged a more aggressive fluid resuscitation. RESULTS The recorded fluid administered within the first 24 h was 5300 [3760; 7100] ml (median [1st; 3rd quartile]). More aggressive volume therapy was associated with disease severity and a higher rate of local complications. There was a linear relationship between administered volume and the maximum C-reactive protein. The amount of administered fluid was significantly attributed to age, hematocrit, and white blood cell count on admission. When adjusted for these parameters the impact of administered volume on outcome was still present but attenuated. CONCLUSIONS We found detrimental effects of fluid therapy on major outcome parameters throughout the whole range of administered volume. More volume was administered in younger patients and in patients with evidence of hemoconcentration and inflammation. The adverse effects of volume therapy persisted after elimination of these parameters. Caution should therefore be advised with regards to volume therapy in patients with acute pancreatitis.

Differential effects of hydrocortisone on sympathetic and hemodynamic responses to sympathoexcitatory manoeuvres in men

Aim of the present study was to investigate the influence of hydrocortisone on muscle sympathetic nerve activity (MSNA) and hemodynamic parameters during different sympathoexcitatory manoeuvres in humans. The study focuses on the interaction of the hypothalamo-pituitary-adrenal system and the sympathetic nervous system. Hydrocortisone 100 mg or placebo was administered intravenously to eight young healthy subjects in a double-blind crossover design. After 6 h, blood pressure, heart rate and MSNA from the peroneal nerve were recorded at rest, during an arithmetic stress task, an apnea and a cold pressor test. Hydrocortisone treatment increased serum cortisol levels to the upper physiological range and suppressed basal levels of adrenocorticotropin. During mental stress, MSNA, heart rate and blood pressure levels were elevated independently of hydrocortisone pre-treatment. However, hydrocortisone induced a sustained increase in basal heart rate throughout the whole experiment. A stronger increase in diastolic blood pressure was observed during apnea and cold pressor test in the hydrocortisone experiments. MSNA or plasma catecholamines at rest or during the manoeuvres were not affected by hydrocortisone. The observed hydrocortisone effects may be due to an increased responsiveness of adrenergic receptors towards catecholamines or a central modulation of the baroreflex involving parasympathetic mechanisms. Further studies are needed to confirm that the increase in MSNA during mental stress does not depend on a concomitant activation of the hypothalamo-pituitary-adrenal system.

Differences between students and physicians in their entitlement towards procedural skills education--a needs assessment of skills training in internal medicine.

Objective: Procedural skills education has a high priority for medical students. However, it is not clear what kind of skills they consider important and whether their perception differs from the physicians’ view. Methods: We conducted a survey on 26 skills in internal medicine among medical students and physicians. Ninety-five fourth year and 62 final year students along with 67 physicians working in medical departments participated in the survey. A similar but smaller survey was completed earlier before the implementation of a skills training at the faculty. Results: Students generally preferred technically complex skills while, in contrast, physicians found “bed-side-skills” more important. The result was independent of the students’ participation in the skills training or of the physicians’ experience. A similar result was achieved in the smaller survey before the implementation of the skills training. Conclusion: Students and physicians significantly differ in their entitlement towards procedural skills education. This should be considered when educational strategies are being discussed.

Low Birth Weight and Increased Sympathetic Activity

To the Editor: In a recent study on twins, IJzerman et al1 report an association between low birth weight and a short pre-ejection period at rest and during stress tests. They interpret their findings as evidence for an increased sympathetic nervous activity in low birth weight subjects. These data elucidate an important aspect in the regulation of the sympathetic system in low birth weight subjects. However, on the background of a study of our group, which examined muscle sympathetic nerve activity (MSNA) in low birth weight singletons,2 the interpretation of the results may have to be modified. In our study, sympathetic neural activity to the muscle vascular bed was determined by specific intraneural measurement. Under resting conditions, MSNA was lower in low birth weight subjects as compared with a control group with normal birth weight. Baroreflex function was also examined and showed normal functional properties. Additionally, sympathoexcitatory maneuvers (inspiratory apnea …