HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 98/1/274    most recent 01380.2003v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Singh, B. Articles by Finucane, K. E. Search for Related Content PubMed PubMed Citation Articles by Singh, B. Articles by Finucane, K. E.

Diaphragm electromyogram root mean square response to hypercapnia and its intersubject and day-to-day variation

¹Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, ²West Australian Sleep Disorders Research Institute, QEII Medical Centre, and ³Department of Physiology, University of Western Australia, Nedlands, Western Australia, Australia

Submitted 22 December 2003 ; accepted in final form 31 August 2004

Diaphragm activation can be quantified by measuring the root mean square of crural EMG (RMSdi) (Beck J, Sinderby C, Lindstrom L, and Grassino A, J Appl Physiol 85: 1123–1134, 1998). To examine intersubject and day-to-day variation in the RMSdi-PCO₂ relationship, end-tidal PCO₂, minute ventilation (E), respiratory frequency (f_B), and RMSdi were measured in seven healthy subjects on two occasions during steady-state ventilation at seven levels of inspired O₂ fraction (FI_CO2) from 0 to 0.08 in random order. RMSdi was measured with a multielectrode esophageal catheter and controlled for signal contamination and diaphragm position. RMSdi was normalized for values obtained during quiet breathing at functional residual capacity, at FI_CO2 of 0.04, and during an inspiratory capacity maneuver (RMSdi%max) as well as ECG R-wave amplitude at functional residual capacity (RMSdi/ECG_R), f_B, and thickness of the costal diaphragm measured by ultrasound. RMSdi increased linearly with PCO₂ (mean r² = 0.83 ± 0.10); at the highest FI_CO2, RMSdi%max was 40.2 ± 11.6%. Relative to the intersubject variation in the E-PCO₂ relationship, intersubject variations in the slopes and intercepts of the RMSdi-PCO₂ relationships were 1.7 and 1.8 times, respectively, and RMSdi%max-PCO₂ relationships 0.9 and 1.3 times, respectively, and were unrelated to f_B and diaphragm thickness. Relative to the day-to-day variation in the E-PCO₂ relationship, day-to-day variation in the slopes and intercepts of the RMSdi-PCO₂ relationships were 2.8 and 4.4 times, respectively, and RMSdi/ECG_R-PCO₂ relationships 1.3 and 2.2 times, respectively. It was concluded that the RMSdi-PCO₂ relationship measures chemosensitivity and is best compared between subjects via RMSdi%max and on separate occasions in the same subject via RMSdi/ECG_R.

diaphragm activation; esophageal catheter; normalization; electrocardiogram

This article has been cited by other articles:

				K. E. Finucane, J. A. Panizza, and B. Singh Efficiency of the normal human diaphragm with hyperinflation J Appl Physiol, October 1, 2005; 99(4): 1402 - 1411. [Abstract] [Full Text] [PDF]