A compact, on-airway, respiratory gas analyzer for performing pulmonary function tests incorporates an IR spectroscopy light guide having a curved, rather than linear, sample chamber that lies transverse to a direction of respiratory gas flow. Cooperating with the sample chamber is an impact plate that functions to steer respiratory and test gases impinging on the impact plate into the curved sample chamber. A source of IR energy is at one end of the sample chamber and an electro-optical sensor responsive to IR energy is disposed at an opposite end of the chamber. The respiratory gas analyzer also includes gas flow paths and valving for carrying out lung capacity and lung diffusion tests.

The present invention discloses a method to determine the lung clearance index (LCI) or other indices of ventilation inhomogeneity of the lungs by combining two pulmonary gas exchange techniques; Inert gas rebreathing (IGR) is used for rapid wash-in of the inert tracer gas and this is followed by multiple-breath wash-out (MBW). The functional residual capacity (FRC) can either be determined from the tracer gas concentration and the gas flow inhaled and exhaled during multiple-breath wash-out or by gas analysis alone from the inert gas rebreathing. The cumulative expired volume (V.sub.CE) required to clear the inert tracer gas from the lungs is determined from the multiple-breath wash-out, and LCI is calculated as the ratio between V.sub.CE and FRC. The advantages of the method are i) significant reduction of required test time, ii) significant reduction of consumed gas mixture for wash-in of tracer gas, iii) potential for further reduction of the use of tracer gas, and iv) potential for more accurate determination of the FRC by gas dilution alone. Furthermore the present invention relates to a corresponding system and computer-readable medium.

A compact, on-airway, respiratory gas analyzer for performing pulmonary function tests incorporates an IR spectroscopy light guide having a curved, rather than linear, sample chamber that lies transverse to a direction of respiratory gas flow. Cooperating with the sample chamber is an impact plate that functions to steer respiratory and test gases impinging on the impact plate into the curved sample chamber. A source of IR energy is at one end of the sample chamber and an electro-optical sensor responsive to IR energy is disposed at an opposite end of the chamber. The respiratory gas analyzer also includes gas flow paths and valving for carrying out lung capacity and lung diffusion tests.

The disclosure is directed to intrapleural air leak detection and monitoring. According to various embodiments of the disclosure, an air leak may be detected utilizing at least one sensor to determine whether fluid extracted from a pleural cavity of a patient includes carbon dioxide and/or a second substance. The second substance may be a foreign substance inhaled by the patient to confirm presence of the air leak. The air leak may be further monitored over a period of time by collecting temporally successive measurements associated with detected concentrations of carbon dioxide. Therefore, tissue damage and recovery may be assessed according to objectively collected criteria.

The invention provides a save and non-invasive alternative to the traditional modified Evans blue dye test for dysphagia in intubated patients. The method employs direct application of dye to the tongue, in combination with a tracheal tube that provides suction in the subglottal region above the cuff. By keeping the cuff inflated, the aspiration of food and liquid, as used in the traditional test, is avoided entirely.

The disclosure is directed to intrapleural air leak detection and monitoring. According to various embodiments of the disclosure, an air leak may be detected utilizing at least one sensor to determine whether fluid extracted from a pleural cavity of a patient includes carbon dioxide and/or a second substance. The second substance may be a foreign substance inhaled by the patient to confirm presence of the air leak. The air leak may be further monitored over a period of time by collecting temporally successive measurements associated with detected concentrations of carbon dioxide. Therefore, tissue damage and recovery may be assessed according to objectively collected criteria.

Systems and methods for generating MRI images of the lungs and/or airways of a subject using a medical grade gas mixture comprises between about 20-79% inert perfluorinated gas and oxygen gas. The images are generated using acquired .sup.19F magnetic resonance image (MRI) signal data associated with the perfluorinated gas and oxygen mixture.

Methods, devices, and systems are disclosed for implementing a fully quantitative non-injectable contrast proton MRI technique to measure spatial ventilation-perfusion (VA/Q) matching and spatial distribution of ventilation and perfusion. In one aspect, a method using MRI to characterize ventilation and perfusion in a lung includes acquiring an MR image of the lung having MR data in a voxel and obtaining a breathing frequency parameter, determining a water density value, a specific ventilation value, and a perfusion value in at least one voxel of the MR image based on the MR data and using the water density value to determine an air content value, and determining a ventilation-perfusion ratio value that is the product of the specific ventilation value, the air content value, the inverse of the perfusion value, and the breathing frequency.

A method for measuring energy malnutrition in a liver disease test subject, a method for determining whether a liver disease test subject is in an energy malnutrition state, a method for determining the necessity of nutrition therapy for a liver disease test subject having energy malnutrition, a composition usable in these methods, and the like are provided. The method for measuring energy malnutrition in a liver disease test subject includes the steps of collecting expired air containing labeled carbon dioxide that is generated in the body of a liver disease test subject by being converted from a composition containing, as an active ingredient, glucose labeled with at least one isotope C; and determining the ratio of labeled CO.sub.2 amount to unlabeled CO.sub.2 amount, or the ratio of labeled CO.sub.2 amount to total CO.sub.2 amount in expired air.

An intubation device is provided. An intubation device comprises a movable guide configured to guide an insertion of an endotracheal tube into a trachea of a patient, the guide having a guide extension and a guide tip; an external trachea identifier source external to the trachea and disposed on the patient during an intubation, wherein the trachea identifier source generates and transmits a signal; at least one trachea condition sensor disposed on the guide tip to detect the signal generated by the trachea identifier source; and a guide control device operatively coupled to the guide, the guide control device configured to move the guide into the trachea in response to the detected signal.