Reproducibility of twitch and sniff transdiaphragmatic pressures.
Twitch transdiaphragmatic pressure (Tw Pdi) measured with magnetic stimulation of the phrenic nerve is used to follow up patients and to assess the effect of clinical treatments on diaphragm function. However the reproducibility of Tw Pdi on different occasions has been little studied. We investigated 32 normal subjects, measuring Tw Pdi elicited by bilateral magnetic stimulation of the phrenic nerves on two to 14 occasions. Sniff transdiaphragmatic pressure (sniff Pdi) was also measured. The mean value of Tw Pdi and sniff Pdi were 28+/-5 and 134+/-24 cm H(2)O, respectively. The within subjects coefficient of variation was 11% for both Tw Pdi and sniff Pdi. We conclude that there is a variability of Tw Pdi and the variability of Tw Pdi is the same as that of sniff Pdi.
Department of Respiratory Medicine and Allergy, Respiratory Muscle Laboratory, Guy's, King's and St Thomas' School of Medicine, King's College Hospital, Bessemer Road, London SE5 9PJ, UK. yuanming.luo@kcl.ac.uk
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Luo
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Hart
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Mustfa
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Man
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Rafferty
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Polkey
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Moxham
D003964:Diaphragm / Q000294:innervation / Q000502:physiology*; D004558:Electric Stimulation / Q000379:methods; D055590:Electromagnetic Phenomena; D006801:Humans; D007320:Inspiratory Capacity; D009119:Muscle Contraction / Q000502:physiology; D010791:Phrenic Nerve / Q000502:physiology*; D011312:Pressure; D015203:Reproducibility of Results; D012119:Respiration; D012680:Sensitivity and Specificity