Methods of determining tissue viability

Abstract

A method of performing a surgical procedure includes generating an infrared image of tissue using a thermographic camera, analyzing the infrared images to determine blood flow characteristics of the tissue, and resecting a portion of the tissue determined to have abnormal blood flow characteristics.

What is claimed is: 
     
         1 . A method of performing a surgical procedure, comprising:
 generating an infrared image of subject tissue of a patient using a thermographic camera;   analyzing the infrared image to determine blood flow characteristics of the subject tissue; and   resecting a portion of the subject tissue determined to have abnormal blood flow characteristics.   
     
     
         2 . The method according to  claim 1 , further comprising stapling the subject tissue upon determining that the subject tissue has normal blood flow characteristics. 
     
     
         3 . The method according to  claim 1 , further comprising comparing the infrared image of the subject tissue with an infrared image of healthy tissue to determine whether the subject tissue exhibits normal blood flow characteristics. 
     
     
         4 . The method according to  claim 1 , further comprising:
 generating an infrared image of tissue known to be healthy using the thermographic camera; and   comparing the infrared image of the tissue known to be healthy with the infrared image of the subject tissue to determine whether the subject tissue exhibits normal blood flow characteristics.   
     
     
         5 . The method according to  claim 1 , wherein the thermographic camera is a thermographic endoscope. 
     
     
         6 . The method according to  claim 1 , wherein analyzing the infrared image to determine blood flow characteristics of the subject tissue includes determining a rate at which the subject tissue returns to a baseline temperature from a temperature below the baseline temperature. 
     
     
         7 . The method according to  claim 6 , further comprising reducing a temperature of the subject tissue from the baseline temperature to the temperature below the baseline temperature by contacting the subject tissue with pre-chilled tissue contacting surfaces of a tissue grasper. 
     
     
         8 . The method according to  claim 1 , further comprising determining a local perfusion pressure of the subject tissue by applying pressure to the subject tissue using a tissue grasper. 
     
     
         9 . The method according to  claim 8 , further comprising:
 determining a systemic blood pressure of the patient;   calculating a first index using the determined local perfusion pressure and the determined systemic blood pressure; and   determining viability of the subject tissue based on the first index and the determined blood flow characteristics of the subject tissue.   
     
     
         10 . The method according to  claim 1 , wherein the subject tissue is a pair of bowel segments. 
     
     
         11 . The method according to  claim 10 , further comprising determining that ends of the pair of bowel segments have normal blood flow characteristics. 
     
     
         12 . The method according to  claim 11 , further comprising stapling the ends of the pair of bowel segments to reconnect the pair of bowel segments after determining that the ends of the pair of bowel segments have normal blood flow characteristics. 
     
     
         13 . The method according to  claim 12 , wherein determining that the ends of the pair of bowel segments have normal blood flow characteristics includes analyzing the infrared image to determine whether the ends of the pair of bowel segments exhibit normal heat distribution characteristics. 
     
     
         14 . A method of performing a surgical procedure, comprising:
 applying pressure to a subject tissue;   removing the pressure applied to the subject tissue;   generating an infrared image of the subject tissue using a thermographic camera after removing the pressure applied to the subject tissue;   observing a rate at which the subject tissue increases in temperature using the infrared image; and   determining whether the subject tissue increases in temperature at a rate associated with healthy tissue.   
     
     
         15 . The method according to  claim 14 , further comprising resecting a portion of the subject tissue that increases in temperature at a rate associated with unhealthy tissue. 
     
     
         16 . The method according to  claim 14 , further comprising stapling the subject tissue upon determining that the subject tissue increases in temperature at the rate associated with healthy tissue. 
     
     
         17 . The method according to  claim 14 , further comprising reducing a temperature of the subject tissue prior to generating the infrared image of the subject tissue. 
     
     
         18 . The method according to  claim 17 , wherein the pressure is applied to the subject tissue using a tissue grasper and the temperature of the subject tissue is reduced by contacting the subject tissue with pre-chilled tissue-contacting surfaces of the tissue grasper. 
     
     
         19 . The method according to  claim 14 , wherein the subject tissue is a pair of bowel segments, the method further comprising resecting a portion of at least one of the pair of bowel segments upon determining that the portion of at least one of the pair of bowel segments increases in temperature at the rate associated with unhealthy tissue. 
     
     
         20 . The method according to  claim 19 , further comprising stapling ends of the pair of bowel segments to reconnect the pair of bowel segments upon determining that the ends of the pair of bowel segments increase in temperature at the rate associated with healthy tissue.