Method and system for measuring pulmonary artery circulation information

Abstract

Minimally invasive systems and methods are described for measuring pulmonary circulation information from the pulmonary arteries. A transbronchial Doppler ultrasound catheter is advanced through the airways and in the vicinity of the pulmonary artery. Doppler ultrasound energy is sent through the airway wall and across the pulmonary artery to obtain velocity information of blood flowing through the artery. The velocity information is used to compute pulmonary circulation information including but not limited to flowrate.

What is claimed is: 
     
         1 . A transbronchial method for the automated determination of an instantaneous volume flow rate within a blood vessel of a patient, the method comprising:
 processing, with a signal processing unit, signals obtained by an ultrasound transducer of a transbronchial catheter positioned inside an airway of a lung, the ultrasound transducer being positioned in the vicinity of the blood vessel of the patient; and   analyzing, with a processor, the processed signals to determine the instantaneous volume flow rate within the blood vessel of the patient.   
     
     
         2 . The method of  claim 1 , wherein the determination of the instantaneous volume flow rate within the blood vessel of the patient is performed without directly measuring a diameter of the blood vessel of the patient. 
     
     
         3 . The method of  claim 1 , wherein the blood vessel is a pulmonary artery of the patient. 
     
     
         4 . The method of  claim 1 , wherein the processor is integral with the signal processing unit. 
     
     
         5 . The method of  claim 4 , wherein the signal processing unit is a Doppler signal processing unit. 
     
     
         6 . The method of  claim 1 , wherein the transbronchial catheter is a Doppler transbronchial catheter and the ultrasound transducer is a Doppler ultrasound transducer. 
     
     
         7 . The method of  claim 1 , wherein the determination of the instantaneous volume flow rate is further based on a diametric limit of the blood vessel that is identified using at least some of the processed signals. 
     
     
         8 . The method of  claim 1 , wherein the determination of the instantaneous volume flow rate includes performing a summation of a plurality of flow rates across discrete area cross sections, and at least some of the discrete area cross sections are within the blood vessel. 
     
     
         9 . The method of  claim 8 , wherein the summation ceases when calculations for the instantaneous volume flow rate no longer increase in value or when a rate of increase of the instantaneous volume flow rate falls below a predetermined threshold. 
     
     
         10 . The method of  claim 8 , wherein the summation comprises a plurality of iterations corresponding to the plurality of flow rates, and wherein the determined instantaneous volume flow rate is calculated in a last iteration of the plurality of iterations. 
     
     
         11 . A medical system for determining an instantaneous volume flow rate within a blood vessel of a patient, the system comprising:
 a transbronchial catheter having an ultrasound transducer, the ultrasound transducer configured to obtain signals when the transbronchial catheter is positioned inside an airway of a lung of the patient and the ultrasound transducer is positioned in the vicinity of the blood vessel of the patient;   a signal processing unit that processes the signals obtained by the ultrasound transducer of the transbronchial catheter, and   a processor that analyzes the processed signals to determine the instantaneous volume flow rate within the blood vessel of the patient.   
     
     
         12 . The system of  claim 11 , wherein the processor determines the instantaneous volume flow rate within the blood vessel of the patient without using a diameter measurement of the blood vessel of the patient. 
     
     
         13 . The system of  claim 11 , wherein the blood vessel is a pulmonary artery of the patient. 
     
     
         14 . The system of  claim 11 , wherein the processor is integral with the signal processing unit. 
     
     
         15 . The system of  claim 14 , wherein the signal processing unit is a Doppler signal processing unit. 
     
     
         16 . The system of  claim 11 , wherein the transbronchial catheter is a Doppler transbronchial catheter and the ultrasound transducer is a Doppler ultrasound transducer. 
     
     
         17 . The system of  claim 11 , wherein the processor determines the instantaneous volume flow rate using a diametric limit of the blood vessel that is identified using at least some of the processed signals. 
     
     
         18 . The system of  claim 11 , wherein the processor determines the instantaneous volume flow rate by performing a summation of a plurality of flow rates across discrete area cross sections, and at least some of the discrete area cross sections are within the blood vessel. 
     
     
         19 . The system of  claim 18 , wherein the processor ceases the summation when calculations for the instantaneous volume flow rate no longer increase in value or when a rate of increase of the instantaneous volume flow rate falls below a predetermined threshold. 
     
     
         20 . The system of  claim 18 , wherein the summation comprises a plurality of iterations corresponding to the plurality of flow rates, and wherein the processor determines the instantaneous volume flow rate based on a last iteration of the plurality of iterations.