Hypokalemia and Hyperkalemia in Infants and Children: Pathophysiology and Treatment

Potassium is the second most abundant cation in the body. About 98% of potassium is intracellular and that is particularly in the skeletal muscle. Electrical disturbances associated with disorders of potassium homeostasis are a function of both the extracellular and intracellular potassium concentrations. Clinical disorders of potassium homeostasis occur with some regularity, especially in hospitalized patients receiving many medications. This article will review the pathophysiology of potassium homeostasis, symptoms, causes, and treatment of hypo- and hyperkalemia.     

Fetal brady- and tachyarrhythmias: new and accepted diagnostic and treatment methods

Sustained bradyarrhythmias are typically the result of symptomatic sinus bradycardia, atrial bigeminy or complete atrioventricular (AV) block. Fetal tachyarrhythmias relate to sinus tachycardia, atrial flutter and supraventricular tachycardia as the main aetiology. Ultrasound is essential to understand the underlying arrhythmia mechanism, to study the impact on cardiac function, to exclude cardiac defects or tumours, and to survey the fetal heart rate and well-being, e.g. during anti-arrhythmic treatment. Based on retrospective studies, several more or less safe, effective and well-tolerated anti-arrhythmic agents are currently available for the treatment of atrial and supraventricular tachycardia. Isolated congenital complete AV block is mainly related to maternal anti-Ro/La auto-antibodies. The rationale to treat a fetus at this irreversible stage of AV nodal damage is primarily to mitigate or prevent concomitant myocardial inflammation and to augment cardiac output. A recently published study demonstrated a significant improved outcome with transmaternal dexamethasone and β-stimulation.     

Sleep and obesity in children and adolescents

The purpose of this review is to provide a comprehensive update of epidemiologic studies that have assessed the association between sleep and obesity risk. Data suggest that short sleep is associated with an increased risk for being or becoming overweight/obese or having increased body fat. Late bedtimes are also a risk factor for overweight/obesity. Findings also suggest that changes in eating pathways may lead to increased body fat. Future experimental studies are needed to enhance our understanding of the underlying mechanisms through which sleep may play a role in the development and maintenance of childhood obesity.     

HIV infection and maternal and child health

During the last three years, there had been several publications from USA and Africa, highlighting maternal and child health problems in HIV infection. Available data suggest that pregnancy might accelerate progression of HIV infection in the mother. About 50% of infants born to HIV infected mothers are likely to be infected at birth or in the neonatal period. Nearly half of the infected infants die before two years of age. HIV infection in childhood following transfusion of blood from HIV infected donor has been reported. There had been speculations on the possible role of improperly sterilised syringes and needles in transmission of HIV infection in Africa. The available guideline drawn by national (Centre for Disease Control, Atlanta,USA) and international (WHO) agencies regarding provision of MCH care to HIV infected individuals and in situations where information on HIV infection status of the person is not known are reviewed, with special reference to the situation in developing countries like India.     

镇痛镇静治疗的发展历史与现状

疼痛和焦虑等是ICU患者常见的不良感受.现代医学已越来越认识到提高危重患者治疗舒适性的重要性.镇痛镇静治疗日趋受到重视并不断完善,已成为ICU等多学科综合治疗的重要组成部分.该文仅就古今中外镇痛镇静治疗的发展历史、国内外ICU镇痛镇静治疗现状、儿童与成人的区别等几个方面进行介绍.     

Neuromuscular function and balance of prepubertal and pubertal blind and sighted boys

Aim : To compare the neuromuscular function and balance of blind prepuberty- and puberty-aged boys to those with normal sight. Methods : Thirty-three prepubertal (aged 9–13 y) and pubertal (aged 15–18 y) blind and sighted boys were tested for muscle mass thickness, electromyography and maximal isometric strength, dynamic explosive actions, and balance. Results : There was no difference in the muscle mass thickness, maximal strength or vertical jump between the blind and sighted boys. However, fitness-ball throwing and five-jump distances were significantly shorter in both blind groups compared to the sighted groups. One-leg stance of the prepuberty-aged sighted boys was 109 (67) s and in blind boys 32 (12) s, and in the puberty-aged boys 120 (57) s and 31 (8) s, respectively. When vision was blocked in the sighted boys, differences between the blind and sighted boys disappeared.
Conclusion : The results showed comparable performance between prepubertal and pubertal blind and sighted boys in the static physical fitness tests. However, balance and performance in dynamic multi-joint tests did not improve similarly in the blind groups compared to sighted groups, indicating that maturation, learning and experience by themselves cannot compensate for the loss of sight.     

Dyskinetic and dystonic cerebral palsy and birth

Two hundred and nineteen cases of the dyskinetic and dystonic forms of cerebral palsy which were seen in the course of three decades at a single clinic have been analysed. Fifty-seven patients had kernicterus. In the remaining 162, 71% of whom were born at term, birthweight was below the expected mean in two-thirds. There was no relationship between birth weight, or abnormal birth, or asphyxia, and the ultimate clinical severity of the children. We conclude that abnormal birth and asphyxia are not direct causes of the cerebral damage, but are expressions of a pre-existing condition resulting in susceptibility to the stress of birth, whether it is normal or abnormal.     

Symptoms and signs differentiating croup and epiglottitis

Aim: To determine differentiating symptoms and signs of epiglottitis and laryngotracheobronchitis (croup). Methods: Contemporaneous interview of parents and clinical examination of children with acute upper airway obstruction presenting to the intensive care unit of a paediatric hospital. Results: Two hundred and three children were examined over a 40‐month period. One hundred and two had croup, of whom 49 had the diagnosis confirmed at intubation and another six by direct laryngeal inspection without intubation. One hundred and one had epiglottitis of whom 95 were diagnosed by direct inspection of the larynx at intubation, five by a lateral X‐ray of the neck and one on direct inspection without intubation. One child with epiglottitis died. Although both illnesses presented with stridor, the additional presence of drooling had a high sensitivity (0.79, 95% CI 0.70–0.86) and specificity (0.94, 95% CI 0.88–0.97) for epiglottitis while coughing had a high sensitivity (1.00, 95% CI 0.96–1.00) and high specificity (0.98, 95% CI 0.93–0.99) for croup. Coughing predicted croup but drooling predicted epiglottitis. Additional reliable signs of epiglottitis were a preference to sit, refusal to swallow and dysphagia. Thirty‐seven percent of children with epiglottitis and 16% with croup were treated as having another respiratory illness at least once before definitive diagnosis. Conclusions: Epiglottitis and croup are often confused because they share symptoms and signs including stridor. However, differentiation in early illness is possible by additional observation of coughing and absence of drooling in croup and by the additional observation of drooling with absence of coughing in epiglottitis.     

Pubertal growth and development and prenatal and lactational exposure to polychlorinated biphenyls and dichlorodiphenyl dichloroethene

OBJECTIVES: Polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethene (DDE) are ubiquitous toxic environmental contaminants. Prenatal and early life exposures affect pubertal events in experimental animals. We studied whether prenatal or lactational exposures to background levels of PCBs or DDE were associated with altered pubertal growth and development in humans.Study design: Follow-up of 594 children from an existing North Carolina cohort whose prenatal and lactational exposures had previously been measured. Height, weight, and stage of pubertal development were assessed through annual mail questionnaires. RESULTS: Height of boys at puberty increased with transplacental exposure to DDE, as did weight adjusted for height; adjusted means for those with the highest exposures (maternal concentration 4+ ppm fat) were 6.3 cm taller and 6.9 kg larger than those with the lowest (0 to 1 ppm). There was no effect on the ages at which pubertal stages were attained. Lactational exposures to DDE had no apparent effects; neither did transplacental or lactational exposure to PCBs. Girls with the highest transplacental PCB exposures were heavier for their heights than other girls by 5.4 kg, but differences were significant only if the analysis was restricted to white girls. CONCLUSIONS: Prenatal exposures at background levels may affect body size at puberty.     

Withholding and withdrawing artificial nutrition and hydration

Although the practice of withholding and withdrawing artificial nutrition and hydration (ANH) has become more common, it remains controversial, particularly in the paediatric setting. Decisions regarding ANH, along with other medical interventions, should be considered in the individual context of the child's overall plan of care. The purpose of the present practice point is to provide guidance for Canadian paediatric health care practitioners regarding when withholding or withdrawing ANH may be an ethically permissible option as part of a palliative care plan and to briefly address some pragmatic considerations.