Current Pediatric Reviews - Volume 2, Issue 3, 2006

Adequate functional residual capacity (FRC) is difficult to create with manual ventilation in very preterm infants and carries a high risk for creating lung damage. International guidelines for neonatal resuscitation do not provide ventilation guidelines for very preterm infants despite evidence that a different approach may be warranted. Peak inspiratory pressures (PIPs) generated with bag and mask ventilation are usually insufficient to open up the lung or unintentionally excessive. The long time constant of the fluid-filled immature lung can be overcome by delivering a prolonged inflation at a lower PIP, followed by application of positive end-expiratory pressure (PEEP) to maintain FRC after lung recruitment. To minimize the damage provoked by manual ventilation a consistent PIP, adequate PEEP and prolonged inflation have to be guaranteed. A mechanical pressure-limited T-piece resuscitator is the only device that meets these requirements. Leakage between mask and face is prevented by using the nasopharyngeal route. After resuscitation, FRC can be preserved by starting nasal continuous positive airway pressure (nCPAP) in the delivery room, which will reduce the need for intubation and mechanical ventilation. This review discusses the accumulated data supporting these recommendations.

The carotid bodies are the main peripheral oxygen sensors involved in cardio-respiratory control under normoxic and hypoxic conditions. The present review briefly describes carotid body function during "normal" development and then presents recent results showing how environmental factors affect the trajectory of these developmental processes. This review then focuses on data obtained from our laboratories, which emphasise the shortterm modulation and long-term consequences of perinatal stress such as premature deprivation of placental steroids and neonatal disruption of mother-infant interactions on carotid body development and function. Our current data suggest that disturbances related to early deprivation of placental steroids, as it occurs with premature delivery, disrupt respiratory chemoreflexes attributed mainly to chemoreceptor cells' ability to respond to changes in oxygen levels during early life. Conversely, stress related to interference with normal mother-pup interactions during the neonatal period induces changes in carotid body function that persist well into adulthood. In both cases, changes in carotid body function are related (at least in part) to significant modification of dopaminergic neurotransmission within the carotid body as suggested by treatment-related changes in dopamine D2 receptor gene expression level. Together, these data suggest that these environmental factors predispose to the occurrence of respiratory disease associated with respiratory control dysfunction such as sleep-disordered breathing during infancy.

Blood pressure is the direct product of cardiac output and total peripheral resistance. Cardiac output is regulated by preload, myocardium contractility and heart rate, while total peripheral resistance depends on afterload and vessel elasticity. The maintenance of blood pressure within normal limits is influenced by neural, humoral and local control mechanisms, which have extensive and complex interactions, making difficult an individual analysis. Thus, isolated or combined disarrangements in these mechanisms can lead to the development of hypertension. Neural blood pressure regulation mainly depends on lower brain stem centers of cardiovascular control and the autonomous nervous system, integrating the cardiovascular reflexes. In regard to humoral mechanisms, several substances/ systems contribute for increasing blood pressure (Angiotensin II, circulating cathecolamines), while others can play a counterregulatory role [Angiotensin-(1-7), kallikrein-kinin system and natriuretic peptides]. Moreover, local factors, such as nitric oxide and endothelins, act as determinants of vascular resistance and as systemic or local modifiers of neural and humoral mechanisms. Recently, research has begun to disclose the mechanisms related to blood pressure regulation at cellular and molecular level. In this review, we discussed experimental and clinical evidence relating to regulatory mechanisms probably involved in the pathophysiology of arterial hypertension with insights from pediatric studies.

Assessment of renal function is important. The gold-standard marker is glomerular filtration rate (GFR) measured by inulin clearance normalized to a standard body surface area of 1.73 m2. Inulin, no longer available in North America, has been replaced by nuclear medicine tests such as 51Cr EDTA, 99mTc DTPA and iothalamate clearances. The use of serum creatinine as a surrogate endogenous marker is hampered by height, gender and muscle mass variability,substantial tubular secretion in advanced renal failure and non-standardized measurements. The limitations of creatinine can be reduced when applying height/creatinine ratios with gender and age-dependent constants that have to be established for each center. The small molecular weight protein cystatin CysC shows a significantly better diagnostic performance for the detection of impaired GFR than serum creatinine. It also does not undergo tubular secretion in chronic renal failure, nor does it show significant non-renal elimination. Its concentration falls in the first year of life with the rise of GFR and remains constant thereafter until 60 years of age in both sexes. GFR can be estimated reliably with a recently published formula without the need for any additional anthropological data. CysC allows for reliable estimation of GFR in children.

Malnutrition is highly prevalent in critically ill children. Several studies have recently reinforced the relationship between poor nutritional status and higher incidences of complications, mortality, length of hospital stay and costs. A variety of methods used for assessment of different components of energy expenditure has been validated and used in critically ill children. Although reference values derived from representative groups of healthy children and adolescents are now available, hypercatabolism along with hypometabolism or hypermetabolism is frequently seen in critically ill children. Methods for assessment of the different components of energy expenditure have been validated in critically ill children and adolescents. There are, however, significant disadvantages of the available tools and of the methodological aspects of assessment of energy expenditure in a pediatric intensive care setting. The combined use of these methods together with detailed analyses of body composition is recommended for future studies. Although, the evaluation of nutritional status is a broad topic that encompasses several clinical variables, in patients with acute critically illness measurements of energy expenditure are necessary.

Pain arising from the chest area creates anxiety in children and their parents, often leading to unnecessary activity restriction, school absences, and medical utilization. A thorough but pragmatic evaluation requires a grasp of the pathophysiology of several organ systems and an understanding of epidemiologic and behavioral patterns specific to children. Few symptoms in pediatrics test a clinician's skill more than chest pain. Though the etiology is frequently benign, it is often uncertain, and sprinkled among cases of chest pain are potentially fatal conditions. This review summarizes chest pain in children of all ages, with particular emphasis on adolescents. We review the organic causes including musculoskeletal trauma, strain and inflammation, respiratory conditions such as occult asthma, pneumonia and bronchitis, and the important role of esophageal disease. We discuss the relatively minor role of cardiac disease, but highlight the conditions that are vital to consider, such as arrhythmia, mitral valve disease, Kawasaki syndrome, Marfan syndrome, and cocaine use. Anxiety, depression, and other psychological factors often further complicate the presentation. A pediatrician's best tools are diagnostic acumen, which may be lifesaving, and supportive dialogue, to impart reassurance to a worried family. We explore the most common and most lethal causes by age, organ system, and predisposing illness. We review the neuroanatomic considerations important in visceral, chest wall, and mediastinal pain, and the sensation within the lung,airways, and pleurae. Lastly, we highlight pragmatic "take-home" tips for the clinician, most of which involve good history-taking and physical examination, but also include the utility of basic testing that can detect the rare cases of fatal cardiopulmonary disease.

The incidence of complicated parapneumonic effusions in children has been increasing over the past decade despite the increasing use of protein-conjugate vaccines against Streptococcus pneumoniae, the most common cause of complicated pneumonia in children in the developed world. Despite the fact that this condition is increasingly common in hospitalized children, the management of this condition remains controversial, in large part due to the small number of prospective, controlled trials evaluating therapies. This review will highlight the epidemiology, diagnosis and management of complicated parapneumonic effusions. The role for intrapleural fibrinolytic therapy and early videoassisted thorascopic surgery in the management of this condition will be emphasized as will the questions that need to be answered with future inquiry.

The purpose of this systematic review is to investigate back pain as a clinical presentation in childhood and adolescence providing the clinician with a comprehensive approach, which will enable for an early recognition of those spinal disorders in need of more aggressive medical intervention. The current literature suggests that young people have a fairly high incidence of non-specific back pain, which seems to be much more frequent than traditionally reported. In schoolchildren, low back pain is mainly associated with psychosocial factors and seems to be mostly benign and selflimiting, therefore, only occasionally requiring medical attention. However, young patients who seek medical assistance, have a higher incidence of organic conditions that can manifest with spinal pain as their predominant symptom. The evaluation of a child or adolescent presenting with back pain can be a challenging task and requires skilled clinical expertise and a high index of suspicion. The physician should have a carefully planned strategy for assessing the pediatric spine patient, which should be accurate, reliable, consistent, and easily reproducible in delineating spinal pathologies. This should include a detailed history, physical examination, radiographic imaging, and appropriate diagnostic laboratory studies. A specific diagnosis will be established in at least 50% of the patients. In certain cases, an exact diagnosis cannot be made, and it is always advisable to re-evaluate the child after a period of initial observation. By then more serious problems will advance and become more obvious while minor symptoms not linked to an underlying pathology will resolve spontaneously. The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or non-profit organization with which the authors are affiliated or associated.