Compensatory Exercise Hyperventilation is Restored in the Morbidly Obese After Bariatric Surgery.

BACKGROUND: Morbidly obese individuals may have poor compensatory hyperventilation during exercise. The objective was to examine pulmonary gas exchange and the compensatory hyperventilatory response during exercise pre- and post-weight reduction surgery in obese subjects. METHODS: Fifteen patients (age = 39 +/- 8 years, body mass index = 47 +/- 6 kg/m(2)), with an excess weight of 69 +/- 17 kg, were recruited. Pulmonary function at rest was assessed and arterial-blood gases were sampled at rest and all levels of exercise pre- and 10 +/- 3 weeks postsurgery. RESULTS: There was a loss of excess weight 21 +/- 6 kg (p < 0.01). Waist and hip circumference decreased by 13 +/- 9 and 8 +/- 7 cm, respectively (p < 0.01). Prior to surgery, there was no compensatory hyperventilation between rest and peak exercise as arterial PCO(2) (PaCO(2)) remained unchanged (37+/- 3 mm Hg). However, postsurgery, there was compensatory hyperventilation as PaCO(2) decreased to 33 +/- 2 mm Hg at peak exercise (p < 0.01), with no change in peak oxygen consumption (VO(2peak) in L/min). Multiple linear regression revealed that the restored ventilatory response to exercise was most strongly associated with the reduction in overall fat mass (adjusted r (2) = 0.25; p = 0.03). Total weight loss of 21 kg induces adequate compensatory hyperventilation that begins to show at about 50% of VO(2peak), resulting in improved gas exchange at moderate to peak exercise intensities. CONCLUSION: Improvement in compensatory hyperventilation is most closely related to loss in overall fat mass.

Zavorsky GS, Kim DJ, Christou NV.

Department of Obstetrics, Gynecology and Women’s Health, School of Medicine, Saint Mary’s Health Center, Saint Louis University, 6420 Clayton Road, Room 290, Saint Louis, MO, 63117, USA, zavorsky@slu.edu.

Browser\’s Notes.

MRI appearance of muscle denervation.

Muscle denervation results from a variety of causes including trauma, neoplasia, neuropathies, infections, autoimmune processes and vasculitis. Traditionally, the diagnosis of muscle denervation was based on clinical examination and electromyography. Magnetic resonance imaging (MRI) offers a distinct advantage over electromyography, not only in diagnosing muscle denervation, but also in determining its aetiology. MRI demonstrates characteristic signal intensity patterns depending on the stage of muscle denervation. The acute and subacutely denervated muscle shows a high signal intensity pattern on fluid sensitive sequences and normal signal intensity on T1-weighted MRI images. In chronic denervation, muscle atrophy and fatty infiltration demonstrate high signal changes on T1-weighted sequences in association with volume loss. The purpose of this review is to summarise the MRI appearance of denervated muscle, with special emphasis on the signal intensity patterns in acute and subacute muscle denervation.

Kamath S, Venkatanarasimha N, Walsh MA, Hughes PM.

Department of Radiology, University Hospital of Wales, Heath Park, Cardiff, CF14 4XW, UK, kamathsridhar@yahoo.com.

[Ethics for beginners.]

Radbruch L.

Klinik für Palliativmedizin, RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Deutschland, LRadbruch@ukaachen.de.