On the mechanism of glucose release from the muscle of juvenile diabetics in acute insulin deficiency

In fifty-three healthy subjects and twenty-three juvenile diabetics the measurement of arterial and deep venous glucose concentrations showed that the substrate was taken up by the tissues of the forearm of all the healthy subjects and released from it in all the diabetic ones. In six of the diabetics glucose output was accelerated almost five-fold during the intrabrachial arterial administration of metaproterenol (1.62 nmol/min), indicating that basal glucose release from muscle may result from enhanced glycogenolysis during acute insulin deficiency. In line with this view a reduction of glucose uptake by muscle was observed in six healthy subjects receiving metaproterenol infusion. However, since the production of lactate by the forearm appeared to be smaller in the diabetics, the basal glucose output could also partly be due to impaired glycolysis. These data suggest that the glucose released from muscle during acute insulin deficiency may be of clinical importance, especially when the rate of glycogenolysis is further stimulated by, for example, enhanced catecholamine drive.     

Rate Response of a Closed-Loop Stimulation Pacing System to Changing Preload and Afterload Conditions

Closed-loop stimulation (CLS) is a new sensor concept for rate adaptive pacing measuring changes in the unipolar right ventricular impedance, which correlates to changes of the right ventricular contractility and reflects the autonomic nervous innervation of the heart. Some patients do not tolerate the CLS mode because of inappropriate tachycardia, mainly related to postural changes. This study tested if the rate response of the CLS sensor is influenced not only by myocardial contractility but also by rapid changes in right ventricular filling. In 12 patients (10 men, median age 77 years) with a Biotronik Inos²-CLS DDDR pacemaker and 14 controls (13 men, median age 59 years) head-up tilt and handgrip testing was performed to provoke rapid changes in pre- and afterload. Tilting the pacemaker patients resulted in a nonphysiological steep increase of the sensor rate (increase >20 beats/min, peak after 1 minute, return to baseline within 2–3 minutes), which was significantly different from the control group, showing only a slight rise in intrinsic heart rate immediately after tilting. Simultaneously to the rapid increase in sensor rate, the pacemaker patients showed a marked orthostatic decline of systolic blood pressure. During handgripping, heart rate and blood pressure curves were similar in both groups. In patients with this CLS pacemaker, rapid preload reduction during head-up tilting caused an overshooting sensor rate increase, reproducing the authors' clinical observation of postural pacemaker tachycardia in some patients. Consequently, they concluded that the rate response of the CLS pacing system can be inappropriately influenced by rapid shifts of blood volume, affecting right ventricular filling. (PACE 2003; 26[Pt. I]:1504–1510)     

Why a Large Tip Electrode Makes a Deeper Radiofrequency Lesion:

Increase in RF Lesion Depth with Larger Electrode. Introduction: Increasing electrode size allows an increase in radiofrequency lesion depth. The purpose of this study was to examine the roles of added electrode cooling and electrode-tissue interface area in producing deeper lesions. Methods and Results: In 10 dogs, the thigh muscle was exposed and superfused with heparinized blood. An 8-French catheter with 4- or 8-mm tip electrode was positioned against the muscle with a blood flow of 350 mL/min directed around the electrode. Radiofrequency current was delivered using four methods: (1) electrode perpendicular to the muscle, using variable voltage to maintain the electrode-tissue interface temperature at 60°C; (2) same except the surrounding blood was stationary; (3) perpendicular electrode position, maintaining tissue temperature (3.5-mm depth) at 90°C; and (4) electrode parallel to the muscle, maintaining tissue temperature at 90°C. Electrode-tissue interface temperature, tissue temperature (3.5- and 7.0-mm depths), and lesion size were compared between the 4- and 8-mm electrodes in each method. In Methods 1 and 2, the tissue temperatures and lesion depth were greater with the 8-mm electrode. These differences were smaller without blood flow, suggesting the improved convective cooling of the larger electrode resulted in greater power delivered to the tissue at the same electrode-tissue interface temperature. In Method 3 (same tissue current density), the electrode-tissue interface temperature was significantly lower with the 8-mm electrode. With parallel orientation and same tissue temperature at 3.5-mm depth (Method 4), the tissue temperature at 7.0-mm depth and lesion depth were greater with the 8-mm electrode, suggesting increased conductive heating due to larger volume of resistive heating because of the larger electrode-tissue interface area. Conclusion: With a larger electrode, both increased cooling and increased electrode-tissue interface area increase volume of resistive heating and lesion depth.     

Socioeconomic inequalities in the health of children and adolescents: A comparative study of the five Nordic countries

Background: Socioeconomic differences in health among adultsexist in the Nordic countries as well as in all other countrieswhere this has been examined. The present study examines whethersuch differences can also be found among children and adolescents,whether these differences vary between the Nordic countriesand whether they can be found in all age groups of childrenand adolescents. Methods: Questionnaires on health, well-beingand socioeconomic status (SES) were sent to parents of a randomsample of children aged 2–17 years, equally distributedbetween Denmark, Finland, Iceland, Norway and Sweden. The indicatorsof reported ill health were having one or more chronic diseases,frequent moderate or severe symptoms and short stature. Thesocioeconomic variables were education and occupation of bothparents and disposable family income. Logistic regression analysiswas used to measure the association between health and SES.Results: Parents in lower socioeconomic groups in all countriesreported more ill health for their children at all ages andtheir children more often belonged to the lowest decile in reportedheight. Sweden and Denmark on the whole showed larger inequalitiesthan the other three countries, but the difference between countrieswas small and varied according to the indicators of ill healthused. The size of the reported health inequalities did not varywith age: the differences were as marked among adolescents asamong younger children. Conclusions: Substantial inequalitiesin health according to SES can be found in childhood and adolescence,even in well-developed welfare states.     

Meaning in Life and Personal Growth among Pediatric Physicians and Nurses

This study examines the factors contributing to middle-aged widows' adaptation to their husbands' death due to physical illness, 1 to 5 years after the initial loss. Ninety-three widows and 93 married women, who served as controls, filled out questionnaires assessing their experience of stress and strain, their Sense of Coherence level, the social support they received, as well as measures of psychological and social adaptation. Results show that several years after their husbands' death, many widows still perceive life events and hassles as significantly more intense experiences than do their married counterparts. Moreover, they report a significantly lower Sense of Coherence, diminished social support and a lower level of mental health, as compared with married women. Multiple regression revealed that Sense of Coherence was the most significant contributor to adaptation variables, especially to mental health. Social support contributed significantly to the 2 social adaptation subscales. The discussion emphasizes the importance of Sense of Coherence to adaptation.     

Effects of norepinephrine on dynamic variables of fluid responsiveness during hemorrhage and after resuscitation in a pediatric porcine model

Background:  The effect of vasopressors on pulse pressure variation (PPV), stroke volume variation (SVV) and on the volumetric variable global end-diastolic volume (GEDV) during changing loading conditions is currently under debate. The aim of our study was to investigate the effect of norepinephrine (NE) on PPV, SVV and GEDV in a pediatric animal model of hemorrhage and resuscitation.
Methods:  Eight anesthetized piglets were studied at normovolemia, after stepwise blood withdrawal (25 ml·kg⁻¹), after infusion of NE to restore mean arterial pressure (MAP), after NE titration was stopped and shed blood was retransfused and finally again after NE titration. Stroke volume (SV) was measured using a thermodilution pulmonary artery catheter. GEDV was measured by transpulmonary thermodilution. PPV and SVV were monitored continuously by pulse contour analysis. In response to NE administration during hemorrhage, MAP significantly increased ( P  < 0.01), PPV significantly decreased ( P  = 0.02), whereas SVV, SV and GEDV remained unchanged. After retransfusion, SVV and GEDV significantly correlated with volume induced percentage change in SV. This significant correlation was reversed after NE administration for SVV and persisted for GEDV. In conclusion, NE administration significantly affected PPV and SVV, whereas the volumetric variable GEDV remained unchanged.     

Influence of anesthetic management on quality of magnetoencephalography scan data in pediatric patients: a case series

Background:  Magnetoencephalography (MEG) is increasingly used in the presurgical evaluation of pediatric seizure patients. Many pediatric patients require sedation or anesthesia to tolerate these exams. However, the available literature on anesthetic management in this population is very limited.
Methods:  We retrospectively reviewed the records of all patients who underwent MEG scanning at our institution with regard to the interaction of anesthetic management and quality of scan data.
Results:  High-dose propofol infusions (≥200 μg·kg⁻¹·min⁻¹) were associated with high frequency artifacts that interfered with the identification of epileptiform discharges. Lower-dose propofol infusions (≤100 μg·kg⁻¹·min⁻¹) did not produce artifacts but required co-administration of fentanyl to prevent patient motion. Dexmedetomidine infusions were not associated with signal artifacts and prevented patient motion very well in our initial patients and became our standard technique.
Conclusion:  In our experience, dexmedetomidine infusions are preferable to propofol-based techniques for pediatric MEG scans due to the absence of adverse effect on interictal activity.