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. Author manuscript; available in PMC: 2010 Oct 1.
Published in final edited form as: Anesth Analg. 2009 Oct;109(4):1209–1218. doi: 10.1213/ane.0b013e3181b0fc70

Figure 3.

Figure 3

An example of the nasal pressure (Pn) vs. maximum inspiratory airflow (VImax) relationships in one female subject (ID = p) and one male subject (ID = M) during passive and active conditions. Upstream resistance (RUS) was defined as the reciprocal of slope of the relationship between VImax and PN, and critical closing pressure (PCRIT) as the x intercept of the regression line. In the passive state for subject - p, PCRIT = −5.7 cmH2O (open triangle) and RUS = 22.2 cmH2O/L/sec. In the active state, PCRIT = −12.0 cmH2O (solid triangle) and RUS = 24.9 cmH2O/L/sec. Similarly for subject M, In the passive state, PCRIT = −7.9 cmH2O (open circle) and RUS = 31.4 cmH2O/L/sec, whereas in the active state, PCRIT = −9.7 cmH2O and RUS = 34.3 cmH2O/L/sec (solid circle). There was a larger increase in difference between the passive and active PCRIT values in subject p, representing a greater improvement in collapsibility in the activated state, compared to subject M.