| 1. |
- Beck, J., et al.
(författare)
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Diaphragmatic function in advanced Duchenne muscular dystrophy
- 2006
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Ingår i: Neuromuscul Disord.. ; 16:3
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess diaphragm electrical activation and diaphragm strength in patients with advanced Duchenne muscular dystrophy during resting conditions. Eight patients with advanced Duchenne muscular dystrophy (age of 25+/-2 years) were studied during tidal breathing, maximal inspiratory capacity, maximal sniff inhalations, and magnetic stimulation of the phrenic nerves. Six patients were prescribed home mechanical ventilation (five non-invasive and one tracheotomy). Transdiaphragmatic pressure and diaphragm electrical activation were measured using an esophageal catheter. During tidal breathing (tidal volume 198+/-83ml, breathing frequency 25+/-7), inspiratory diaphragm electrical activation was clearly detectable in seven out of eight patients and was 12+/-7 times above the noise level, and represented 45+/-19% of the maximum diaphragm electrical activation. Mean inspiratory transdiaphragmatic pressure during tidal breathing was 1.5+/-1.2cmH(2)O, and during maximal sniff was 7.6+/-3.6cmH(2)O. Twitch transdiaphragmatic pressure deflections could not be detected. This study shows that despite near complete loss of diaphragm strength in advanced Duchenne muscular dystrophy, diaphragm electrical activation measured with an esophageal electrode array remains clearly detectable in all but one patient.
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| 2. |
- Hamnegård, Carl-Hugo, 1954
(författare)
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Andningsmuskelfunktion vid KOL
- 2006
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Ingår i: In: KOL Kroniskt obstruktiv lungsjukdom. Larsson K, ed.. ; Kapitel 3.5, s. 153-162
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Hamnegård, Carl-Hugo, 1954, et al.
(författare)
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Does undernutrition contribute to diaphragm weakness in patients with severe COPD?
- 2002
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Ingår i: Clinical Nutrition. ; 21:3, s. 239-243
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: The assumption that undernourishment contributes to diaphragm weakness in chronic obstructive pulmonary disease (COPD) remains unproven. METHODS: We, therefore, studied diaphragm strength, measured as transdiaphragmatic pressure during a maximal voluntary sniff (Sn P(di)) and cervical magnetic stimulation (Tw P(di)), in two groups of 10 patients with severe COPD. The groups had equally severe COPD as judged by FEV(1) and thoracic gas volume (V(tg)). The malnourished group had a mean body mass index (BMI) of 17.3 kg/m(2) compared with 27 kg/m(2) for the normally nourished group (mean difference -9.7 kg/m(2); 95% confidence intervals -6.8 to -12.6 kg/m(2),P <0.0001). RESULTS: There was no significant difference between Tw P(di) (mean difference 2.1 cm H(2)O; 95% CI-3 to + 7.4 cm H(2)O, P=0.39) or Sn P(di) (mean difference -2.4 cm H(2)O; 95% CI-21 cm H(2)O to +16 cm H(2)O,P =0.8). CONCLUSION: We conclude that undernourishment of the severity studied does not contribute to diaphragm weakness in severe COPD.
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| 4. |
- Hamnegård, Carl-Hugo, 1954, et al.
(författare)
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Effect of lung volume reduction surgery for emphysema on diaphragm function
- 2006
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Ingår i: Respir Physiol Neurobiol.. ; 150:2-3
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Tidskriftsartikel (refereegranskat)abstract
- Preoperative prediction of a successful outcome following lung volume reduction surgery (LVRS) for emphysema is imperfect. One mechanism could be improvement in respiratory muscle function yet controversy exists regarding the magnitude and mechanism of such an improvement. Therefore, we measured diaphragm strength in 18 patients before and after LVRS. Mean (S.D.) FRC fell from 6.53 to 5.40l (p=0.0001). Mean sniff transdiaphragmatic pressure increased from 76 to 87cmH(2)O (14%, p<0.03) and mean twitch transdiaphragmatic pressure (Tw Pdi) increased by 2.5cmH(2)O at 3 months (12%, p=0.03). There was a highly significant increase in twitch esophageal pressure (Tw Pes) (60%, p<0.0001), which was maintained at 12 months (46% increase, p=0.0004). No change was observed in quadriceps twitch tension in nine subjects in whom it was measured. After LVRS the ratio Tw Pes:Tw Pdi increased from 0.24 to 0.37 at 3 months (p=0.0003) and 0.36 at 12 months (p=008). Low values of Sn Pdi, Sn Pes, Tw Pes and a high RV/TLC ratio were the preoperative variables most predictive of improvement in shuttle walking distance. We conclude that LVRS improves diaphragm function primarily by alteration of lung volume. Patients with poor diaphragm function and high RV/TLC ratio preoperatively are most likely to benefit from the procedure.
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| 5. |
- Hamnegård, Carl-Hugo, 1954, et al.
(författare)
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Quadriceps strength assessed by magnetic stimulation of the femoral nerve in normal subjects
- 2004
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Ingår i: Clin Physiol Funct Imaging. ; 24:5
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Tidskriftsartikel (refereegranskat)abstract
- Summary Magnetic stimulation of the femoral nerve is a new technique for assessment of quadriceps strength by measurement of twitch tension (TwQ), a test that is independent of subject motivation. In this study, we sought to establish better define normal values by measurement of TwQ in 45 normal subjects. Supramaximal stimulation, as judged by TwQ, was achieved in 43 of 45 subjects at a mean of 90% of maximum stimulator output. The mean TwQ was 7.3 kilograms force (kgf) (SD 2.3) for women and 9.8 kgf (SD 2.5) for men. The mean maximal voluntary contraction (MVC) force was 48.0 kgf (SD 9.2) for women and 70.1 kgf (15.2) for men. The mean TwQ/MVC ratio was 0.15 for both women and men. Significant correlations were observed between TwQ and weight (r = 0.33, P<0.03) and height (r = 0.32, P<0.03) but these were weak and only partially explained observed variance. Our data confirm that magnetic femoral nerve stimulation is generally acceptable to naive subjects. Values are provided as a function of weight in normal subjects.
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| 6. |
- Hart, N., et al.
(författare)
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A novel clinical test of respiratory muscle endurance
- 2002
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Ingår i: Eur Respir J. ; 19:2
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Tidskriftsartikel (refereegranskat)abstract
- Impaired respiratory muscle endurance (RME) could reduce exercise tolerance and contribute to ventilatory failure. The aim of the present study was to develop a clinically-feasible method to measure RME using negative-pressure inspiratory-threshold loading. It was hypothesized that endurance time (tlim) could be predicted by normalizing oesophageal pressure-time product (PTP) per total breath cycle (PTPoes) for maximum oesophageal pressure (Poes,max); the load/capacity ratio. The corresponding mouth pressures, PTPmouth and Pmouth,max were also measured. The RME test was performed on 30 healthy subjects exposed to the same target pressure (70% of Poes,max). Eight patients with systemic sclerosis/interstitial lung disease were studied to assess the validity and acceptability of the technique. Normal subjects showed a wide intersubject variation in tlim (coefficient of variation, 69%), with a linear relationship demonstrated between log tlim and PTPoes/Poes,max (r=0.88). All patients with systemic sclerosis/interstitial lung disease had normal respiratory muscle strength, but six out of eight had a reduction in RME. In conclusion, endurance time can be predicted from the load/capacity ratio, over a range of breathing strategies; this relationship allows abnormal respiratory muscle endurance to be detected in patients. Oesophageal and mouth pressure showed a close correlation, thus suggesting that the test could be applied noninvasively.
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