Figure 1
From: Diaphragm weakness in mechanically ventilated critically ill patients
Transdiaphragmatic twitch pressure: measured levels and physician estimates. (A) Transdiaphragmatic twitch pressure (PdiTw) levels for the 57 subjects included in the analysis. Each symbol represents a single subject and plots the PdiTw level obtained in response to stimulation of the phrenic nerves with 95% of maximum magnetic field strength (y axis) against the PdiTw obtained in response to stimulation of the phrenic nerves with 100% of maximum magnetic field strength (x axis). All data cluster along the line of identity, indicating that supramaximal stimulation was achieved during 100% magnetic field stimulation. If supramaximal conditions had not been achieved, data points would have fallen to the right of the line of identity. (B) Measured PdiTw levels compared with levels predicted for each subject by their attending physicians; each symbol represents data from a single patient. Red symbols below the line (46 out of 51 determinations) indicate determinations for which physicians overestimated diaphragm strength (that is, PdiTw).