U.S. Patent No. 4909259-Method and Apparatus for Determining the Metabolic Rate Ratio
- U.S. Patent No: 4909259
- Issued on: March 21, 1990
- Category: Metabolic Rate Ratio
Tehrani, Fleur T., U.S. Patent No. 4909259, Method and Apparatus for Determining the Metabolic Rate Ratio, issued on March 21, 1990.
Abstract
An apparatus and method determine the metabolic rate ratio (MRR) of a patient from data indicative of (a) oxygen and carbon dioxide concentrations of the patient, and (b) cardiac function of the patient. The cardiac function data may be either heart rate and stroke volume of the patient, or cardiac output data from a cardiac output monitor that noninvasively and continuously monitors cardiac output. A CO2 analyzer and either an O2 analyzer or a pulse oximeter may be employed to provide the oxygen and carbon dioxide concentration data. Heart rate data is provided by either a pulse monitor or is obtained from the patient’s ECG. The present invention permits the measurement of MRR at any level of patient activity as well as during transitions inactivity.
Description
The present invention relates to a method and apparatus for determining a patient’s metabolic rate ratio. More particularly, the present invention relates to a method and apparatus for determining a patient’s metabolic rate ratio from (1) data indicative of carbon dioxide and oxygen pressures of the patient’s arterial blood and (2) data indicative of either (a) the patient’s heart rate and stroke volume, or (b) the patient’s cardiac output if monitored noninvasively and continuously.
Background of the Invention
Devices for determining the metabolic rate of a patient are generally known in the art. Known devices measure the patient’s oxygen uptake by one means or another to provide a measure of metabolic rate. For example, U.S. Pat. No. 4,572,208, discloses a method and apparatus that measures oxygen uptake as an indicator of metabolic rate. Oxygen uptake can be measured: on a breath-by-breath basis, as taught by U.S. Pat. No. 4,368,740; by introducing a known amount of an inert gas (i.e., helium) into the patient’s airways, as taught by U.S. Pat. No. 4,221,224; or by using an airtight system for patients under artificial respiration, as taught by U.S. Pat. No. 4,753,245.