Indirect calorimeter for medical applications

A ventilator system adapted to be placed in fluid communication with an airway of a patient comprising:

• a supply of inhalation respiratory gas;
• a respiratory conduit providing a flow pathway for an inhalation and exhalation respiratory gas flowing therethrough;
• an inlet conduit operatively connected between the supply of respiratory gas and the respiratory conduit for directing an inhalation respiratory gas to the patient;
• a return conduit operatively connected between the supply of inhalation respiratory gas and the ventilator, for returning exhalation respiratory gas to the supply of respiratory gas;
• a valve disposed between the inlet conduit, respiratory conduit and outlet conduit for controlling the flow of gas to each of the conduits;
• a respiratory gas analyzer operatively positioned in the patient's airway, wherein the respiratory gas analyzer includes a disposable flow module having a flow path operatively connected to a non-disposable electronics module;
• an ultrasonic flow sensor in fluid communication with the flow path for detecting gas flow volume in the flow path;
• and
• a gas component sensor in fluid communication with the flow path for detecting gas component concentration levels in the flow path, wherein the electronics module uses the gas flow volume and gas component concentration level to determine a metabolic rate of the patient.

A system for providing intravenous feeding to a person connected to a ventilator, the method comprising:

• a ventilator system, having a holder adapted to receive a flow module;
• an indirect calorimeter, comprising a non-disposable electronics module and a disposable flow module, the flow module enclosing a flow path, the flow module being placed within the holder of the ventilator system so that gases respired by the person pass through the flow path;
• an intravenous feeding unit, the unit comprising a source of intravenous food, a delivery tube for delivering the food to the person, and a pump adapted to pump intravenous food from the source along the delivery tube at a controlled pump rate;
• and
• a communications link between the indirect calorimeter and the infusion pump, so as to modify the controlled pump rate of food to the person according to data provided by the indirect calorimeter.

A ventilator system adapted to be placed in fluid communication with an airway of a patient comprising:

• a supply of inhalation respiratory gases;
• a respiratory conduit providing a flow pathway for an inhalation and exhalation respiratory gas flowing therethrough;
• a flow module holder located within the conduit;
• and
• a respiratory gas analyzer, the analyzer comprising:
• a flow module, adapted to be placed within the flow module holder in the conduit, so that the inhalation and exhalation respiratory gases pass through a flow path of the flow module, the flow module containing a flow rate sensor for determining a flow rate of the inhalation and exhalation respiratory gases, wherein the flow module is disposed in the airway of the patient and includes a generally cylindrical housing enclosing the flow path, a pair of ultrasonic transducers positioned to transmit and receive ultrasonic pulses along a direction having a direction component along the flow path, a flexible tube disposed between the flow module and a valve unit, and a capnometer in the exhalation conduit for measuring a volume of carbon dioxide in the exhaled respiratory gas, and
• an electronics module, adapted to be connected to the flow module, and adapted to calculate a respiratory parameter using the determined flow rate of the inhalation and exhalation respiratory gases flowing through the flow path.

A ventilator system for assisting a patient in breathing comprising:

• a supply of inhalation respiratory gases;
• a respiratory conduit providing a flow pathway for an inhalation and exhalation respiratory gas flowing therethrough between said supply of inhalation respiratory gases and the patient;
• a valve disposed within said respiratory conduit for controlling the flow of inhalation and exhalation respiratory gases;
• a flow module holder located within the conduit between said valve and the patient;
• a gas component sensor, sensitive to a respiratory gas component, operable so as to provide a signal correlated with an instantaneous concentration of a respiratory gas component;
• and
• a respiratory gas analyzer located between said valve and the patient, the analyzer comprising:
• a flow module, adapted to be placed within the flow module holder in the conduit, so that the inhalation and exhalation respiratory gases pass through a flow path of the flow module, the flow module containing a flow rate sensor disposed in the flow path of the flow module for determining a flow rate of the inhalation and exhalation respiratory gases, and
• an electronics module, adapted to be integrally connected to the flow module, and adapted to calculate a respiratory parameter using the determined flow rate of the inhalation and exhalation respiratory gases flowing through the flow path.