Table 1 Cut off values for the diagnosis of weakness for each respiratory muscle test

Test	Sex	Calculation	Cut off(cm H₂O)	Rounded(cm H₂O)
Pimax	M	10.4–1.96 × 3.0 kPa	44.8	45
Pimax	F	7.2–1.96 × 2.1 kPa	31.6	30
Sniff Poes	M	105–1.96 × 26 cm H₂O	54.0	55
Sniff Poes	F	92–1.96 × 22 cm H₂O	48.9	50
Sniff Pnasal	M	0.91 × 55 cm H₂O	50.1	50
Sniff Pnasal	F	0.91 × 50 cm H₂O	45.5	45
Sniff Pdi	M	148–1.96 × 24 cm H₂O	101.0	100
Sniff Pdi	F	121–1.96 × 25 cm H₂O	72.0	70
Twitch Pdi	M & F	28–1.96 × 5 cm H₂O	18.2	18
Pemax	M	14.4–1.96 × 3.3 kPa	80.5	80
Pemax	F	9.1–1.96 × 1.6 kPa	61.1	60
Cough Pgas	M	214.4–1.96 × 42.2 cm H₂O	131.7	130
Cough Pgas	F	165.1–1.96 × 34.8 cm H₂O	96.9	95
Twitch T10	M & F	x = 1.6–1.96 × 0.20re-transformation: y = 10^x	16.1	16

Pimax, maximum inspiratory pressure; Poes, oesophageal pressure; Pnasal, nasal pressure; Pdi, transdiaphragmatic pressure, Pemax, maximum expiratory pressure; Pgas, gastric pressure.