Apparatus and method for identifying FRC and PEEP characteristics

Abstract

A ventilator for ventilating a patient also assists a clinician in determining a suitable PEEP for the patient. For this purpose, a graph or tabular display of a series of different value PEEPs and corresponding functional residual capacities of the patient may be provided. Or, the relationship between lung compliance and a series of different values of PEEP may be provided. Or, the amount of the lung volume recruited / de-recruited at various levels of PEEP may be determined for use in selecting a desired PEEP. To this end, the functional residual capacity of the lungs is determined for a first PEEP level. The PEEP is then altered to a second level and a spirometry dynostatic curve of lung volume and pressure data is obtained. The lung volume on the dynostatic curve at a lung pressure corresponding to the first PEEP value is obtained. The difference between the functional residual capacity of the lungs at the first PEEP level and that determined from the dynostatic curve represents the lung volume recruited / de-recruited when changing between said first and second PEEPs.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] The present application claims the priority of U.S. Provisional Application No. 60 / 719,329, filed Sep. 21, 2005, and comprises a continuation-in-part of U.S. patent application Ser. No. 11 / 358,573, filed Feb. 21, 2006, which application also claims priority of U.S. Provisional Application No. 60 / 719,329.BACKGROUND AND SUMMARY [0002] The present invention relates to an apparatus and method for determining and displaying functional residual capacity data and other pulmonary parameters, such as positive end expiratory pressure (PEEP) data, for patients breathing with the aid of a mechanical ventilator, such as a critical care ventilator. The invention also determines and displays relationships between these and other parameters. [0003] Functional residual capacity (FRC) is the gas volume remaining in the lungs after unforced expiration or exhalation. Several methods are currently used to measure functional residual capacity. In the body ple...

AI Technical Summary

Benefits of technology

[0022] The apparatus and method of the present invention also determines and displays a showing of the amount of lung volume recruited or de-recruited as the PEEP is changed. This allows the clinician to distinguish between changes in functional residual capacity due to lung stretching or contracting and those arising from recruitment or de-recruitment.

Problems solved by technology

But in many cases, patients that could benefit from a determination of functional residual capacity are so seriously ill as to not be breathing spontaneously but by means of a mechanical ventilator, such as a critical care ventilator.

This circumstance has heretofore proven to be a significant impediment in obtaining functional residual capacity information from such patients.

Additionally, the patient's illness may also make it impossible or inadvisable to move the patient to a laboratory or into and out of a body box for the determination of functional residual capacity.

If this resistance cannot be overcome, the volume of such sacs are not included in the functional residual capacity of the patient's lungs.

However, setting the PEEP too high can cause excessive lung distension.

Either of these circumstances present the possibility of adverse consequences to the patient.

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