What role does the right side of the heart play in circulation?
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Right ventricular failure (RVF) is an underestimated problem in intensive care. This review explores the physiology and pathophysiology of right ventricular function and the pulmonary circulation. When RVF is secondary to an acute increase in afterload, the picture is one of acute cor pulmonale, as occurs in the context of acute respiratory distress syndrome, pulmonary embolism and sepsis. RVF can also be caused by right myocardial dysfunction. Pulmonary arterial catheterization and echocardiography are discussed in terms of their roles in diagnosis and treatment. Treatments include options to reduce right ventricular afterload, specific pulmonary vasodilators and inotropes. (+info)
Alveolar hypoventilation and hyperosmnia in myotonic dystrophy.
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A case of myotonic dystrophy accompanied by alveolar hypoventilation and hypersomnia is presented. Radiological studies and EMG examination of the intercostal muscles demonstrated that the respiratory muscles were affected by the disease, while polygraphic recordings showed that the alveolar hypoventilation and pulmonary hypertension worsened during sleep. The hypersomnia preceded the appearance of clinical signs of the muscular disease by many years and persisted even after treatment when the blood gas analysis values were greatly improved. During both diurnal and nocturnal sleep, the patient frequently fell asleep directly into a REM stage. The possibility is discussed that, concomitant with the respiratory musculature involvement, there is an alteration in the central nervous system in myotonic dystrophy which is at least partially responsible for both the alveolar hypoventilation and the hypersomnia. (+info)
Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive. (+info)
Hyperleptinaemia, respiratory drive and hypercapnic response in obese patients.
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Leptin is a powerful stimulant of ventilation in rodents. In humans, resistance to leptin has been consistently associated with obesity. Raised leptin levels have been reported in subjects with sleep apnoea or obesity-hypoventilation syndrome. The aim of the present study was to assess, by multivariate analysis, the possible association between respiratory centre impairment and levels of serum leptin. In total, 364 obese subjects (body mass index >or=30 kg.m(-2)) underwent the following tests: sleep studies, respiratory function tests, baseline and hypercapnic response (mouth occlusion pressure (P(0.1)), minute ventilation), fasting leptin levels, body composition and anthropometric measures. Subjects with airways obstruction on spirometry were excluded. Out of the 346 subjects undergoing testing, 245 were included in the current analysis. Lung volumes, age, log leptin levels, end-tidal carbon dioxide tension, percentage body fat and minimal nocturnal saturation were predictors for baseline P(0.1). The hypercapnic response test was performed by 186 subjects; log leptin levels were predictors for hypercapnic response in males, but not in females. Hyperleptinaemia is associated with a reduction in respiratory drive and hypercapnic response, irrespective of the amount of body fat. These data suggest the extension of leptin resistance to the respiratory centre. (+info)
Methylene blue for clinical anaphylaxis treatment: a case report.
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CONTEXT AND OBJECTIVE: Nitric oxide has a pathophysiological role in modulating systemic changes associated with anaphylaxis. Nitric oxide synthase inhibitors may exacerbate bronchospasm in anaphylaxis and worsen clinical conditions, with limited roles in anaphylactic shock treatment. The aim here was to report an anaphylaxis case (not anaphylactic shock), reversed by methylene blue (MB), a guanylyl cyclase inhibitor. CASE REPORT: A 23-year-old female suddenly presented urticaria and pruritus, initially on her face and arms, then over her whole body. Oral antihistamine was administered initially, but without improvement in symptoms and signs until intravenous methylprednisolone 500 mg. Recurrence occurred after two hours, plus vomiting. Associated upper respiratory distress, pulmonary sibilance, laryngeal stridor and facial angioedema (including erythema and lip edema) marked the evolution. At sites with severe pruritus, petechial lesions were observed. The clinical situation worsened, with dyspnea, tachypnea, peroral cyanosis, laryngeal edema with severe expiratory dyspnea and deepening unconsciousness. Conventional treatment was ineffective. Intubation and ventilatory support were then considered, because of severe hypoventilation. But, before doing that, based on our previous experience, 1.5 mg/kg (120 mg) bolus of 4% MB was infused, followed by one hour of continuous infusion of another 120 mg diluted in dextrose 5% in water. Following the initial intravenous MB dose, the clinical situation reversed completely in less than 20 minutes, thereby avoiding tracheal intubation. CONCLUSION: Although the nitric oxide hypothesis for MB effectiveness discussed here remains unproven, our intention was to share our accumulated cohort experience, which strongly suggests MB is a lifesaving treatment for anaphylactic shock and/or anaphylaxis and other vasoplegic conditions. (+info)
Chronic respiratory failure in patients with neuromuscular diseases: diagnosis and treatment.
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Neuromuscular diseases affect alveolar air exchange and therefore cause chronic respiratory failure. The onset of respiratory failure can be acute, as in traumas, or progressive (slow or rapid), as in amyotrophic lateral sclerosis, muscular dystrophies, diseases of the myoneural junction, etc. Respiratory muscle impairment also affects cough efficiency and, according to the current knowledge regarding the type of treatment available in Brazil to these patients, it can be said that the high rates of morbidity and mortality in these individuals are more often related to the fact that they cough inefficiently rather than to the fact that they ventilate poorly. In this review, with the objective of presenting the options of devices available to support and substitute for natural ventilation in patients with neuromuscular diseases, we have compiled a brief history of the evolution of orthopedic braces and prostheses used to aid respiration since the end of the 19th century. In addition, we highlight the elements that are fundamental to the diagnosis of alveolar hypoventilation and of failure of the protective cough mechanism: taking of a clinical history; determination of peak cough flow; measurement of maximal inspiratory and expiratory pressures; spirometry in two positions (sitting and supine); pulse oximetry; capnography; and polysomnography. Furthermore, the threshold values available in the literature for the use of nocturnal ventilatory support and for the extension of this support through the daytime period are presented. Moreover, the maneuvers used to increase cough efficiency, as well as the proper timing of their introduction, are discussed. (+info)
Rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation presenting in childhood.
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OBJECTIVE: The goal was to characterize the phenotype and potential candidate genes responsible for the syndrome of late-onset central hypoventilation with hypothalamic dysfunction. METHODS: Individuals with late-onset central hypoventilation with hypothalamic dysfunction who were referred to Rush University Medical Center for clinical or genetic assessment in the past 3 years were identified, and medical charts were reviewed to determine shared characteristics of the affected subjects. Blood was collected for genetic testing of candidate genes (PHOX2B, TRKB, and BDNF) and for high-resolution conventional G-banding, subtelomeric fluorescent in situ hybridization, and comparative genomic hybridization analysis. A subset of these children were studied in the Pediatric Respiratory Physiology Laboratory at Rush University Medical Center. RESULTS: Twenty-three children with what we are now naming rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation were identified. Comprehensive medical charts and blood for genetic testing were available for 15 children; respiratory physiology studies were performed at Rush University Medical Center on 9 children. The most characteristic manifestations were the presentation of rapid-onset obesity in the first 10 years of life (median age at onset: 3 years), followed by hypothalamic dysfunction and then onset of symptoms of autonomic dysregulation (median age at onset: 3.6 years) with later onset of alveolar hypoventilation (median age at onset: 6.2 years). Testing of candidate genes (PHOX2B, TRKB, and BDNF) revealed no mutations or rare variants. High-resolution chromosome analysis, comparative genomic hybridization, and subtelomeric fluorescent in situ hybridization results were negative for the 2 patients selected for those analyses. CONCLUSIONS: We provide a comprehensive description of the clinical spectrum of rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation in terms of timing and scope of symptoms, study of candidate genes, and screening for chromosomal deletions and duplications. Negative PHOX2B sequencing results demonstrate that this entity is distinct from congenital central hypoventilation syndrome. (+info)
Central hypoventilation with PHOX2B expansion mutation presenting in adulthood.
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Congenital central hypoventilation syndrome most commonly presents in neonates with sleep related hypoventilation; late onset cases have occurred up to the age of 10 years. It is associated with mutations in the PHOX2B gene, encoding a transcription factor involved in autonomic nervous system development. The case history is described of an adult who presented with chronic respiratory failure due to PHOX2B mutation-associated central hypoventilation and an impaired response to hypercapnia. (+info)