Influence of methazolamide on the human control of breathing: A comparison to acetazolamide.

New Findings: What is the central question of this study? Acetazolamide and methazolamide both reduce hypoxic pulmonary vasoconstriction equally, but methazolamide does not impair skeletal muscle function. The effect of methazolamide on respiratory control in humans is not yet known. What is the main finding and its importance? Similar to acetazolamide after chronic oral administration, methazolamide causes a metabolic acidosis and shifts the ventilatory CO response curve leftwards without reducing O sensitivity.

Attenuation of human hypoxic pulmonary vasoconstriction by acetazolamide and methazolamide.

Acetazolamide (AZ), a carbonic anhydrase inhibitor used for preventing altitude illness attenuates hypoxic pulmonary vasoconstriction (HPV) while improving oxygenation. Methazolamide (MZ), an analog of acetazolamide, is more lipophilic, has a longer half-life, and activates a major antioxidant transcription factor. However, its influence on the hypoxic pulmonary response in humans is unknown.

Effect of acetazolamide and methazolamide on diaphragm and dorsiflexor fatigue: a randomized controlled trial.

Acetazolamide, a carbonic anhydrase (CA) inhibitor used clinically and to prevent acute mountain sickness, worsens skeletal muscle fatigue in animals and humans. In animals, methazolamide, a methylated analog of acetazolamide and an equally potent CA inhibitor, reportedly exacerbates fatigue less than acetazolamide. Accordingly, we sought to determine, in humans, if methazolamide would attenuate diaphragm and dorsiflexor fatigue compared with acetazolamide.

Exercise-induced quadriceps muscle fatigue in men and women: effects of arterial oxygen content and respiratory muscle work.

Key Points: High work of breathing and exercise-induced arterial hypoxaemia (EIAH) can decrease O delivery and exacerbate exercise-induced quadriceps fatigue in healthy men. Women have a higher work of breathing during exercise, dedicate a greater fraction of whole-body V̇O2 towards their respiratory muscles and develop EIAH. Despite a greater reduction in men's work of breathing, the attenuation of quadriceps fatigue was similar between the sexes.

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients.

Differences in the absolute flow and volume of maximal expiratory flow-volume (MEFV) curves have been studied extensively in health and disease. However, the shapes of MEFV curves have received less attention. We questioned if the MEFV curve shape was associated with (i) expiratory flow limitation (EFL) in health and (ii) changes in bronchial caliber in asthmatics.

Quantifying the shape of the maximal expiratory flow-volume curve in mild COPD.

Maximal expiratory flow-volume (MEFV) curve evaluation using absolute and percent predicted values of flow and volume are used to diagnose respiratory disease, but the shape of the curve is rarely used. Three mathematical methods were used to quantify shape of MEFV curves in subjects with mild COPD (n=19) and matched healthy controls (n=15). Those with mild COPD had a significantly greater slope-ratio (SR) (1.

Hypoxia, not pulmonary vascular pressure, induces blood flow through intrapulmonary arteriovenous anastomoses.

Key Points: Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) is increased by acute hypoxia during rest by unknown mechanisms. Oral administration of acetazolamide blunts the pulmonary vascular pressure response to acute hypoxia, thus permitting the observation of IPAVA blood flow with minimal pulmonary pressure change. Hypoxic pulmonary vasoconstriction was attenuated in humans following acetazolamide administration and partially restored with bicarbonate infusion, indicating that the effects of acetazolamide on hypoxic pulmonary vasoconstriction may involve an interaction between arterial pH and PCO2.

Tracheal Epstein-Barr virus-associated smooth muscle tumour in an HIV-positive patient.

Epstein-Barr virus-related smooth muscle tumours (EBV-SMTs) are a rare but well recognized non-AIDS-defining malignancy that can also be found in several other immunosuppressed states. Pulmonary involvement of EBV-SMTs is not uncommon, but it can present with multifocal lesions in any anatomical site. The present article describes an HIV-positive woman with dyspnea who was found to have a large tracheal EBV-SMT.

Dyspnea due to pulmonary vessel arteritis.

Pulmonary arteritis is a rare cause of pulmonary hypertension. Causes of pulmonary arteritis can be divided into primary and secondary, as well as classified according to vessel size. Only large vessel vasculitis is associated with pulmonary hypertension; primary forms include Takayasu arteritis and giant cell arteritis.

Exercise-induced arterial hypoxemia is unaffected by intense physical training: a case report.

Exercise-induced arterial hypoxemia (EIAH) occurs in some healthy humans at sea-level, whereby the most aerobically trained individuals develop the most severe hypoxemia. A female competitive runner completed 2 maximal exercise tests. Maximal oxygen consumption increased by 15% between testing days, but the degree of hypoxemia remained similar (PaO2, SaO2; 82 and 80 mm Hg; 93.

Systematic review of non-invasive positive pressure ventilation for chronic respiratory failure.

Background: This systematic review examined the effect of non-invasive positive pressure ventilation (NIPPV) on patient reported outcomes (PROs) and survival for individuals with or at risk of chronic respiratory failure (CRF).

Methods: Randomised controlled trials (RCTs) and prospective non-randomised studies in those treated with NIPPV for CRF were identified from electronic databases, reference lists and grey literature. Diagnostic groups included in the review were amyotrophic lateral sclerosis/motor neuron disease (ALS/MND), Duchenne muscular dystrophy (DMD), restrictive thoracic disease (RTD) and obesity hypoventilation syndrome (OHS).

Ulcerative tracheobronchitis due to Aspergillus.

Aspergillus ulcerative tracheobronchitis is a life-threatening form of invasive aspergillosis and is seldom seen in patients without underlying an immunocompromised state. Bronchoscopists must be familiar with this entity and consider Aspergillus ulcerative tracheobronchitis whenever mucosal erosions are seen, especially when unconventional risk factors such as intensive care unit admission and short-term glucocorticoid therapy are present. We present a case of invasive Aspergillus causing widespread ulcerative tracheobronchitis in a 39-year-old man with an asthma exacerbation requiring intensive care unit admission.

Exercise-induced arterial hypoxaemia and the mechanics of breathing in healthy young women.

The purpose of this study was to characterize exercise-induced arterial hypoxaemia (EIAH), pulmonary gas exchange and respiratory mechanics during exercise, in young healthy women. We defined EIAH as a >10 mmHg decrease in arterial oxygen tension ( ) during exercise compared to rest. We used a heliox inspirate to test the hypothesis that mechanical constraints contribute to EIAH.

Repeated exercise-induced arterial hypoxemia in a healthy untrained woman.

A healthy 36-year-old untrained (maximal oxygen consumption (V(O2max)): 39 mL/kg/min) woman completed multiple graded exercise tests on a treadmill. Temperature-corrected arterial blood samples were obtained in addition to esophageal pressure. Significant hypoxemia (-13 mm Hg arterial oxygen tension decrease) and arterial oxyhemoglobin desaturation (-6% decrease) was observed relative to rest and occurred during submaximal exercise and worsened at maximal intensities.

Effect of different single-session educational modalities on improving medical students' ability to demonstrate proper pressurized metered dose inhaler technique.

Objective: Pressurized metered dose inhalers (pMDIs) remain important therapeutic options for obstructive lung diseases. The ability to instruct and evaluate inhaler technique is a crucial skill that all medical professionals should possess; unfortunately, many professionals lack proficiency with pMDIs. We aimed to determine if brief education interventions of differing modalities can positively affect medical students' skills over the long term.