Device for recording and graphic representation of pressure-volume curves

A device for recording and displaying a pressure-volume curve, wherein a gas stream is generated by a gas source under control of a control unit and conveyed via a hose to or from a patient, wherein a flow sensor determines the gas stream and the control unit computes and records an administered gas volume, wherein a pressure sensor determines a gas pressure and the control unit records the gas pressure and determines a pressure slope and determines a pressure-volume curve from the gas pressure and the administered gas volume and displays it on a display screen or stores it for a display, and wherein the control unit performs at least one of the following functions (a) to (d):

• (a) computing the pressure-volume curve for inspiration and/or expiration as a function of the gas stream and the pressure slope and computing and displaying steep portions or straight lines of the pressure-volume curve;
• (b) computing a lower inflection point and an upper inflection point and using the lower inflection point and the upper inflection point in the pressure-volume curve for the display of a straight line which is defined or delimited by the lower inflection point and the upper inflection point;
• (c) using a breath volume from a present or prior respiration to compute a pressure-volume curve j and determining pressures Pawj and/or 0.8 Pawj using a value of j;
• (d) recording a pressure-volume curve for an expiration or determining it, wherein the pressure slope is a negative pressure slope and at least one of the gas stream and the administered gas volume may be negative as well.