Differential effects of repeated inspiratory and limb muscle loading on effort perception in patients with obstructive sleep apnea and healthy males.

Obstructive sleep apnea (OSA) is characterized by collapse of the upper airways during sleep. The contribution of alterations in effort perception is not understood. This study investigated the response of inspiratory and quadriceps muscles to repetitive loading on effort perception in OSA patients, pre and post continuous positive airway pressure (CPAP) treatment, and in healthy individuals. Twenty-one OSA patients and 40 healthy participants completed protocols for repetitive inspiratory and leg muscle loading combined with intermittent rating of perceived exertion (RPE 14-somewhat hard/hard) to assess effort sensitivity. Electromyography, inspiratory pressure and isometric force were measured. OSA patients reported higher fatiguability of respiratory and leg muscles than controls. OSA patients revealed lower effort sensitivity in the leg muscles compared with controls, while repetitive loading led to a decline in force production. In the respiratory system, OSA patients revealed similar effort sensitivity at baseline compared with controls, but a large reduction in effort sensitivity after loading. Baseline effort sensitivity was correlated with apnea-hypopnea index (AHI). After CPAP treatment, OSA patients revealed a decreased baseline effort sensitivity with a missing loading response. Effort sensitivity was differentially affected in the respiratory and leg systems with outcomes of CPAP treatment suggesting a full reversibility. Outcomes suggest that reversible adaptive response of effort perception in the respiratory system might contribute to the severity of OSA.

An act of balance: Interaction of central and peripheral chemosensitivity with inflammatory and anti-inflammatory factors in obstructive sleep apnoea.

OBJECTIVES: Central and peripheral chemosensitivity i.e. ventilatory response to CO2 and O2 are thought to be decisive for ventilatory control instability in obstructive sleep apnoea (OSA). Obesity is associated with chronic low level inflammation. Whether body mass related inflammatory and anti-inflammatory factors influencing peripheral and central chemosensitivity differentially is unclear. METHODS: Ventilatory response to hypercapnic-hyperoxic and hypercapnic-hypoxic gas mixtures in patients with OSA (n = 46) and healthy individuals (n = 45) was measured. C-reactive protein (CRP), leptin, adiponectin, and endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA) were measured in blood samples. RESULTS: Mediation analysis revealed that association of chemoresponse to CO2 with apnoea hypopnea index (AHI) was fully mediated by body mass index (BMI). Regression analysis showed that CRP and leptin levels explained ˜25% and ˜15% of the variance in central CO2 response, while 2-AG explained ˜42% of the variance in peripheral response to hypoxia. CONCLUSION: Inflammatory and anti-inflammatory factors could explain differential alterations in peripheral and central ventilatory chemoresponse in patients with OSA.

Divers revisited: The ventilatory response to carbon dioxide in experienced scuba divers.

PURPOSE: To investigate the ventilatory response to CO2 in hyperoxia, hypoxia, and during exercise amongst experienced scuba divers and matched controls. METHODS: Two studies were performed. The first investigated the CO2 sensitivity in rest and exercise using CO2 rebreathing in hyperoxia at a workload typical for diving with divers (n = 11) and controls (n = 11). The second study examined the respiratory drive of divers (n = 10) and controls (n = 10) whilst breathing four different gas mixtures balanced with N2 (ambient air; 25% O2/6% CO2; 13% O2; 13% O2/6% CO2) to assess the combined response to hypercapnia and moderate hypoxia. RESULTS: Exercise at a load typical for diving was found to have no effect on the ventilatory sensitivity to CO2 in divers (rest: 1.49 ± 0.33; exercise: 1.22 ± 0.55 [l/min × mmHg(-1)]) and controls (rest: 2.08 ± 0.71; exercise: 2.05 ± 0.98 [l/min × mmHg(-1)]) while differences in sensitivity remained between the groups. Inhalation of the four gas mixtures revealed the tested oxygen pressures caused no significant alteration in the ventilatory sensitivity to CO2 in divers and controls. CONCLUSIONS: Experienced divers possess a lower ventilatory response to CO2 which was not affected by exercise or the tested oxygen pressures suggesting a dominant adaptation of central CO2 sensitivity.

Coexistence of bronchiectasis and rheumatoid arthritis: revisited.

The presence of bronchiectasis (BR) in patients with rheumatoid arthritis (RA) has been recognized for many decades; nevertheless, little research has been undertaken in this area. It is important to recognize that BR coexistent with RA differs from the other types of BR. The purpose of this descriptive review was to delineate the epidemiology, etiology, risk factors, pulmonary function testing, imaging, prognosis and management of concomitant BR and RA. To inform our study we searched the PubMed, EMBASE, CINAHL, and MEDLINE databases, using combinations of the following key words: computed tomography, lung function tests, rheumatoid arthritis, bronchiectasis, biological agents, and interstitial lung disease. The number of published papers covering this topic is limited, but several relevant conclusions can be drawn. Patients with concomitant RA and BR have worse obstructive airways disease, increased susceptibility to recurrent pulmonary infections, faster lung function decline, and higher mortality, compared with subjects with either RA or BR alone. The use of disease-modifying anti-rheumatic drugs (both biological and non-biological) for RA in RA-BR patients imparts a further challenge in managing these patients. Although there are not any published guidelines on the management of coexisting RA-BR, we have attempted to provide such recommendations, based on the literature review and our experience.

So, they thought it was all over.

Non-tubercular mycobacteriae (NTM) are ubiquitous organisms found throughout the environment including soil and water. Incidence of NTM infection or isolation is increasing both in immunocompromised as well as immunocompetent patients and may present with a spectrum of disease similar to tuberculosis. The authors report cases of two patients with a background of cancer who presented with NTM infection mimicking lung cancer. The case report is followed by review of reported cases of NTM infections which presented similarly mimicking cancer. Based on their experience and the review of literature the authors recommend that all efforts should be made to obtain tissue for histology and acid fast bacilli examination in all cases which present with lung masses, nodules, bronchiectasis, air-space shadowing or cavity formation especially over a background of structural lung disease. Such cases should be kept under close clinical and radiological follow-up, as cancer and NTM infections can coexist.

An endobronchial lipoma: diagnosis remains a challenge.

Benign tumors of the endobronchial tree are rare, and among them endobronchial lipoma is the least common. It is histologically benign in character but may cause bronchial obstruction. We describe a case of a 68-year-old woman with an endobronchial lipoma arising in the left lower lobe bronchus who had been treated for frequent chest infections for the past 3 years.

Incidental finding of Castleman's disease in an asymptomatic young adult.

Castleman's disease (CD) is a rare lymphoproliferative disorder of unknown aetiology presenting with different clinical manifestations in young adults. There are two main types, unicentric occurring in a younger age group and multicentric occurring in older people. We report the case of 22-year-old man who initially presented with acute appendicitis. During his admission he had a routine chest radiograph which demonstrated a mass lesion, later diagnosed as Castleman's disease of hyaline vascular type. He underwent a right pneumonectomy for complete excision and made an unremarkable recovery.

Spontaneous infection of a stable mediastinal cystic mass: A case report.

Mediastinal cysts have an unpredictable course but can cause complications such as infection or local pressure effects. Persons with mediastinal cysts can be asymptomatic for many years or can develop symptoms as a result of complications of the cyst. There is a lack of consensus on the best approach to managing those patients without symptoms. In this case report, a 56 year old woman with an indolent mediastinal cyst initially managed conservatively suddenly developed symptoms suggestive of an infected mediastinal cyst requiring surgical resection.

Pneumocystis carinii pneumonia infection in a patient with known chronic mucocutaneous candidiasis.

Chronic mucocutaneous candidiasis is a disorder of the skin, nails or mucous membranes in the absence of another cause of the infection. It is also associated with autoimmune endocrinopathies in 40% of patients. It is thought to be due to a T-cell defect, although no precise mechanism has been elucidated. There have been two previous cases of Pneumocystis carinii pneumonia reported with this condition. We report a fatal case in a 34-year-old male.