TRANSDIAPHRAGMATIC PRESSURE IN YOUNG-ADULT SINGAPOREAN SUBJECTS - NORMAL VALUES AND A COMPARISON BETWEEN DIFFERENT RESPIRATORY MANEUVERS

Background: Most published normal values for transdiaphragmatic pressu re (Pdi) have been from Caucasian subjects and there is no universal a greement regarding the most appropriate manoeuvre for assessing Pdi. A ims: The aims of our study were to obtain normal values and to compare the different manoeuvres used to assess Pdi in normal young Singapore an adults. Methods: Twenty-four normal subjects (23 Chinese, one India n) were studied by measuring Pdi during maximal sniffs from functional residual capacity (sniff Pdi), maximal inspiration to total lung capa city (Pdi TLC) and maximal static inspiratory efforts from residual vo lume (Pdi PImax). Results: Mean values +/- SD for sniff Pdi, Pdi TLC a nd Pdi PImax were 101.8 +/- 31.7, 46.8 +/- 26.4 and 83.5 +/- 35.5 cm H 2O respectively. Sniff Pdi was significantly higher than Pdi TLC (p < 0.001) and Pdi PImax (p = 0.005). Pdi PImax was significantly higher t han Pdi TLC (p < 0.001). Males had significantly higher values for sni ff Pdi (p = 0.026) and Pdi PImax (p = 0.022) than females. There was a significant correlation between the different methods of recording Pd i. Sniff Pdi had the highest values, least between- and within-subject variation and most consistent pattern of respiratory muscle recruitme nt with the lowest proportion of negative gastric pressure (Pg) values (p<0.001). Conclusions: Therefore, sniff Pdi may be better than Pdi T LC and Pdi PImax in assessing diaphragm function. Also, our subjects s eemed to have lower sniff Pdi and Pdi PImax, and higher Pdi TLC compar ed with Caucasian subjects.