Current Respiratory Medicine Reviews - Volume 7, Issue 2, 2011

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Full text available.

Standardized exercise testing has almost become a routine procedure in pediatrics. However, exercise testing should only be performed when indications and contraindications for the procedure have been considered and experienced staff and adequate equipment for testing and emergency measures are available. Most tests are conducted in children aged 5 years or older using a treadmill or a cycle ergometer. Various test protocols are available. Most often, protocols requiring a maximal effort are employed. Criteria for a valid maximal test are a plateau in oxygen uptake despite an increase in exercise intensity, a heart rate near the predicted maximum, and a high respiratory exchange ratio. In children with pulmonary or cardiac diseases, these established criteria may not be valid. Exercise testing can be used to diagnose exercise-induced adverse events such as exercise-induced arrhythmias or bronchial constriction, to clarify the cause of a limited exercise capacity, to identify risks associated with exertion such as arterial hypoxemia, and to monitor the progression of an underlying health condition as well as the effects of treatment.

Pulmonary complications are the most common causes of morbidity and mortality in the postoperative period after congenital heart surgery. In this review we discuss the diverse pathological mechanisms that contribute to these pulmonary complications. Both mechanical and gas exchange abnormalities result in increased ventilatory requirements, ICU stay and mortality. Parenchymal lung disease can be caused by a variety of conditions including nosocomial pneumonia, atelectasis and use of cardiopulmonary bypass. Direct surgical trauma to the respiratory system can result in diaphragmatic paralysis, chylothorax, subglottic stenosis or vocal cord paralysis. Disturbances in the pulmonary vasculature can also trigger complications including pulmonary embolism, plastic bronchitis and even pulmonary hypertensive crises in certain at risk populations. Close monitoring with early detection and treatment of complications often prevents prolonged ventilation and hospitalization, e.g., cases of chylothorax where early intervention is beneficial. However, the therapies used to manage some of these complications in the pediatric population are nonspecific and varied e.g., therapies for postoperative atelectasis or treatment of plastic bronchitis. There is a paucity of studies that directly address therapy for many of these complications and more randomized controlled trials in the pediatric population are needed.

Cardiopulmonary exercise testing (CPET) in pediatric patients differs in many aspects from the tests as performed in adults. Children's cardiopulmonary responses during exercise testing present different characteristics, particularly indices of respiratory gas exchange (e.g. oxygen uptake, ventilation and ventilatory efficiency), which are essential in interpreting hemodynamic data. Diseases that are associated with myocardial ischemia are very rare in children. Important indications for CPET in children are the evaluation of exercise capacity and the non-invasive identification of pathologic features. In this article we will review the methodology, and clinical concepts exercise testing and interpretation of respiratory gas-exchange during exercise in children with congenital heart disease.

The modern era of surgical palliation, perioperative strategies, and myocardial preservation has dramatically altered the long-term outcome for children with congenital heart disease. Even children surgically corrected for more complex heart disease are now surviving to ages where physical activity and sports participation are not only considered but encouraged by pediatric cardiologists secondary to the benefits of regular physical activity on cardiovascular risk factors. In this review, basic cardiovascular and pulmonary responses to exercise performance are reviewed. In addition, the interaction of the cardiovascular and pulmonary systems during exercise in children with simple and complex congenital heart disease is reviewed.

Cardio respiratory exercise testing provides an objective measurement of aerobic exercise capacity in patients with congenital heart disease. Many patients with congenital heart disease have decreased exercise capacity despite a lack of symptoms. Patients with simple lesions tend to have better exercise capacity than those with complex lesions, but individual variation exists. The reasons for this impairment in exercise capacity cannot be explained by ventricular dysfunction alone. Chronotropic impairment, disturbances of pulmonary function and deconditioning also play a key role. In patients with congenital heart disease, cardio respiratory exercise testing has prognostic value and could be important in deciding the need for re-interventions.

In a population of patients after successful heart surgery for congenital heart defects (CHD) might emerge noncardiac morbidities. Malfunction of the respiratory system (RS) including chest wall deformities (CWD) may represent risk for a long-term functional performance and QoL of these subjects. This review aims for the long-term (abnormal pulmonary hemodynamics prior to surgery) or short-term (e.g. thoracotomy) harmful impacts on the developing RS. CHD with redundant lung recoil may induce dramatic worsening of the mechanical properties of the RS. Despite successful repair of CHD harmful and successive adaptive processes may affect future development of the RS. Surgical treatment of CHD requires thoracic wall incision (median sternotomy or lateral thoracotomy), which currently with other perioperative impacts may represent unfavourable formation of CWD. Surprisingly, heart surgery itself does not lead either to an improvement or marked change in the severity or frequency of preoperative lung abnormalities (mostly lung volume restriction, hyperinflation, stiff lung or airway obstruction). Causes of RS dysfunction and CWD in patients after surgical repair of CHD are multifactorial. Therefore, a management of these abnormalities especially in adult and aged CHD is difficult. The early primary repair of CHD and recent interventional approaches (e.g., superior ministernotomy or usage of Amplatz occluder) may provide advantages regarding developing organ systems and prevent secondary changes of the heart and the RS. Further research should focus on individual factors in the development of CWD and postoperative respiratory changes. Long-term and/or probably permanent follow up of subjects after CHD repair is a must.

Background: There are ethical issues about randomizing individuals with obstructive sleep apnea-hypopnea syndrome (OSAHS) into groups that receive therapy and those that do not, which means that longitudinal studies are necessary. Objective: To evaluate the effectiveness of nasal continuous positive airway pressure (CPAP) therapy on cardiovascular outcomes in OSAHS patients and to discuss the use of OSAHS treatment. Design: A prospective, patient-based study using retrospective observational data was performed. Cox multivariate regression analysis was performed to determine the adjusted effect of CPAP-treatment on survival in cardiovascular events (CVE). Setting: Sleep Unit of Burgos, Spain. Patients: All 887 patients (791 men) with OSAHS were diagnosed by Polysomnography in the Sleep Unit, between 1997 and 2002. Intervention: CPAP-treatment versus non CPAP-treatment, according to Spanish Society of Pulmonary and Thoracic Surgery (SEPAR) criteria. Measurements: The cardiovascular disease data were obtained from hospital records. Results: The average follow-up period was 4.1 years. CPAP-treatment patients had a higher mean apnea-hypopnea index score than the untreated group (45.9 [Standard Deviation (SD): 28.2] versus 25.3 (SD: 17.8), respectively; P<0.001), as well as a higher Body Mass Index, Epworth and Arousals, but age and sex were similar in both groups. Cardiovascular disease was more common in the untreated group than in the CPAP-treated group during follow-up (3.0 versus 1.99 cardiovascular events/100 persons-years, respectively; P=0.1547). Upon multivariate analysis, age, sex, prior cardiovascular disease, diabetes mellitus and CPAP (hazard ratio= 0.519, 95% confidence interval: 0.288-0.935) remained as statistically significant predictors of survival in cardiovascular events. The mortality rate was greater in women than men. Conclusions: The data support a protective effect of CPAP therapy against cardiovascular disease in patients with OSAHS and different cardiovascular morbidity and mortality by gender. CPAP therapy shows a positive benefit/risk balance.

Increasing use of ultrasonography during pregnancy has uncovered a range of parenchymal lesions within the lung, some of which will, if left, be a cause of morbidity and occasional mortality. These include congenital cystic adenomatoid malformations (CCAM), bronchopulmonary sequestration (BPS), congenital lobar & segmental emphysema and bronchogenic cysts. Adverse antenatal features include mediastinal shift, caval obstruction, and (rarely) hydrops. This review aims to define current thoughts on these lesions and suggest appropriate management.

The identification of different phenotypes within chronic obstructive pulmonary diseases (COPD) can be important for identifying key mechanisms in the disease process and may help guide treatment plans. The term “phenotype”, first coined by the Danish botanist Wilhelm Johannsen in 1909, is defined as “the observable characteristics of an individual resulting from the interaction of its genotype with the environment”. Numerous prognostic factors have been identified in patients with COPD that might enable classification of such patients into different phenotypes. However, the complex networks of interrelationships between the clinical manifestations of COPD and its prognostic factors make phenotypic classification difficult. Recently, a series of composite multidimensional tools - such as the BODE, SAFE, CPI, and ADO indexes - have been developed to reflect the range of comorbidities and the complexity of underlying mechanisms associated with COPD. Another approach would lie in classification systems based on significant independent prognostic factors identified by multivariable analysis. This approach, however, has thus far failed to produce useful clinical diagnostic tools. Future strategies for phenotyping may include a comprehensive assessment of anatomicalclinical- functional prognostic factors in COPD. Incorporation of these factors may eventually broaden our understanding of COPD pathophysiology and may offer an opportunity to tailor treatment.