nutritional support is essential for patients undergoing major surgery , and nutritional therapies such as total parenteral nutrition or enteral nutrition are integral to the management of these patients .
however , surgery causes a state of insulin resistance , and changes in glucose metabolism occur after surgery , and overfeeding with high loads of carbohydrates has been associated with clinical complications .
therefore , knowledge of the optimal energy requirements is very important in the nutritional management of the patients undergoing surgery .
an evaluation of the energy requirements of patients undergoing surgery is critical in planning optimal nutritional therapy .
typically , the total energy of the parenteral or enteral nutrition is determined by using the predicted resting expenditure ( pree ) calculated by the harris - benedict equation , and the total energy requirement is calculated by the pree  activity factor  stress factor . on the other hand ,
there have been several studies reporting that the energy expenditure of patients undergoing surgery changes to a hyper - metabolic status .
however , there have not been any reports on the energy metabolism of patients undergoing a pancreatoduodenectomy .
currently , the pylorus - preserving pancreatoduodenectomy ( pppd ) is generally accepted as the preferred procedure for pancreatic head cancer or bile duct tumors . in this study , we evaluated the change in the energy metabolism of patients undergoing pppd , and determined the optimal energy requirements for their nutritional management .
twelve patients with bile duct cancer or pancreatic tumors ( 5 women and 7 men , median age 70.1 years old ) were enrolled in this study .
the patients were admitted to the gastrointestinal surgery unit of shiga university of medical science hospital .
four patients had pancreatic cancers , 6 patients had bile duct carcinomas , and 2 patients had intraductal papillary mucinous neoplasms ( ipmn ) .
parenteral nutrition was started before surgery in three patients , and parenteral nutrition and enteral nutrition were started on postoperative day ( pod ) 1 in other patients .
the total energy of the parenteral nutrition ( tpn ) , enteral nutrition ( en ) and oral diet was 33.2    7.6  kcal
/ kg / day before surgery , 29.5    7.8  kcal / kg / day on pod 7 and 24.3   8.4  kcal / kg / day on pod 14 .
the mrees and non protein respiratory quotients ( nprq ) were measured by computed open - circuit indirect calorimetry ( ae-300s ; minato medical science co. , osaka , japan ) .
indirect calorimetry ( ic ) was performed in the hospital room on the morning after a 10-h overnight fast before surgery .
however , the infusion of parenteral nutrition was maintained on pod 7 and pod 14 .
the period flow and gas calibration were performed prior to all measurements . after resting for a minimum of 30  min ,
after equilibrium was reached for 10  min , the respiratory exchange was performed continuously over 30  min .
the mree was calculated from the oxygen consumption ( vo2 ) and carbon dioxide production ( vco2 ) by the weir equation .
: mree  =  ( 3.94    vo2  +  1.11    vco2 )    1.44 measurement of the non protein rq was calculated as rq  =  vco2/vo2 .
the measured mree was then compared with the pree ( predicted resting energy expenditure ) calculated by the harris and benedict equation . :
men : pree  =  66.47  +  13.75    w [ weight ( kg ) ]  +  5.0    h [ height ( cm ) ]    6.75    a [ age ( year ) ] . women : pree  =  665.09  +  9.56    w [ weight ( kg ) ]  +  1.84    h [ height ( cm ) ]    4.67    a [ age ( year ) ] .
the results are presented as mean    sd , and a p value < 0.05 was considered to be statistically significant .
twelve patients with bile duct cancer or pancreatic tumors ( 5 women and 7 men , median age 70.1 years old ) were enrolled in this study .
the patients were admitted to the gastrointestinal surgery unit of shiga university of medical science hospital .
four patients had pancreatic cancers , 6 patients had bile duct carcinomas , and 2 patients had intraductal papillary mucinous neoplasms ( ipmn ) .
parenteral nutrition was started before surgery in three patients , and parenteral nutrition and enteral nutrition were started on postoperative day ( pod ) 1 in other patients .
the total energy of the parenteral nutrition ( tpn ) , enteral nutrition ( en ) and oral diet was 33.2    7.6  kcal
/ kg / day before surgery , 29.5    7.8  kcal / kg / day on pod 7 and 24.3   8.4  kcal / kg / day on pod 14 .
the mrees and non protein respiratory quotients ( nprq ) were measured by computed open - circuit indirect calorimetry ( ae-300s ; minato medical science co. , osaka , japan ) .
indirect calorimetry ( ic ) was performed in the hospital room on the morning after a 10-h overnight fast before surgery .
however , the infusion of parenteral nutrition was maintained on pod 7 and pod 14 .
the period flow and gas calibration were performed prior to all measurements . after resting for a minimum of 30  min ,
after equilibrium was reached for 10  min , the respiratory exchange was performed continuously over 30  min .
the mree was calculated from the oxygen consumption ( vo2 ) and carbon dioxide production ( vco2 ) by the weir equation .
: mree  =  ( 3.94    vo2  +  1.11    vco2 )    1.44 measurement of the non protein rq was calculated as rq  =  vco2/vo2 .
the measured mree was then compared with the pree ( predicted resting energy expenditure ) calculated by the harris and benedict equation . :
men : pree  =  66.47  +  13.75    w [ weight ( kg ) ]  +  5.0    h [ height ( cm ) ]    6.75    a [ age ( year ) ] . women : pree  =  665.09  +  9.56    w [ weight ( kg ) ]  +  1.84    h [ height ( cm ) ]    4.67    a [ age ( year ) ] .
the results are presented as mean    sd , and a p value < 0.05 was considered to be statistically significant .
the bmi of these patients was 21.4    3.8  kg / m , and the average total protein , serum albumin , total cholesterol , prealbumin and retinol - binding protein levels were normal .
the mree in these patients determined by indirect calorimetry before the surgery was 1198.0    191.7  kcal / day . on the other hand ,
the pree calculated by the harris - benedict equation was 1174.5    175.2  kcal / day .
there was a positive correlation between the pree and mree ( p<0.05 ) ( fig .  1 ) .
the mree / body weight measured before the operation was almost the same as the pree / body weight ( mree
: 22.4    3.9 kcal / kg / day vs pree : 21.7    2.0  kcal / kg / day ) , and the mree / pree ratio , which reflects the stress factor , was 1.02    0.11 .
there were no significant differences among mrees of the patients with pancreas cancer , bile duct carcinoma and ipmn .
the mree / body weight of these patients was almost the same as that of the controls reported previously .
the nprq of these patients measured by indirect calorimetry before surgery was 0.87    0.06 , and was almost the same as that of the controls reported previously .
as shown in fig .  2 , a significant increase in energy expenditure was observed after pppd .
the mree of the patients undergoing a pppd was 25.7    3.5  kcal / kg / day on pod 7 and 25.4    4.9  kcal
the mree / pree ratio was 1.16    0.14 on pod 7 , and 1.16    0.18 on pod 14 respectively .
however , the nprq did not change significantly during the perioperative period ( fig .  3 ) .
this is the first report on the resting energy expenditure in patients undergoing a pppd . in this study
, we showed that the mree measured by ic in patients with bile duct carcinomas or pancreatic tumors was not elevated before surgery .
their mree was the same as the pree calculated by harris - benedict equation , and was the same as the mree of healthy controls .
previous studies have suggested that the mree may be elevated in patients with specific types of tumors .
it has been reported that patients with lung cancers or sarcomas have increased energy expenditure .
falconer et al . also reported that the ree was significantly elevated in pancreatic cancer patients who were losing weight .
this elevated ree was reported to be associated with some proinflammatory cytokines such as il-6 or tnf-. a progressive increase in tumor size is associated with an increase in oxygen consumption . in our study , however , the patients with bile duct cancer or pancreatic tumors enrolled in this study had an operative indication for pppd , and hence cachexic patients were not included in this study .
the bmis and other nutritional parameters of these patients were within the normal range , and had a good nutritional condition .
this must be the reason why the preoperative ree in these patients was not elevated in this study .
the resting energy expenditure ( pree ) , calculated by the harris - benedict equation , has been widely used to evaluate the energy status of patients .
theoretically , the pree is expected to be equal to the mree in healthy humans , and the mree / pree ratio is a marker for a hyper - metabolic status . in this study ,
the mree was increased after pppd , and was significantly higher than the pree , and was also higher than the preoperative mree ( p<0.05 ) .
the mree / pree , which reflects the stress factor , was elevated to 1.16 on pod 7 and pod 14 . from these results
, it is apparent that the stress factor for bile duct cancer or pancreatic tumors surgery should be 1.2 in patients without major complications .
surgical trauma is generally considered to produce an increase in energy metabolism , and surgical stress , as well as burns or sepsis , causes an increase in the mree .
systemic inflammatory response syndrome ( sirs ) describes a clinical response arising from a non - specific origin .
the elevated mree after surgery was associated with operative sirs , and the mree was further increased in patients with infectious complications .
previously , it has been reported that the ree was significantly increased after abdominal surgery , and tpn therapy consisting 45  kcal / kg day was optimal for these patients .
this means that measurement of energy requirement can be calculated by the pree  1.75 .
1.752.0  kcal / day should be optimal for tpn in the patients undergoing major surgery .
however , federix et al . showed a 10% increase in the mree in patients undergoing gastrointestinal surgery without major complication .
shaw et al . also reported that the infusion of 110% of ree may be suitable for tpn in patients with gastrointestinal surgery .
our results showed that the mree was almost 25.5  kcal / kg / day just after pppd surgery , and the mree / pree ratio was 1.16 on pod 7 and pod 14 .
the measurement of energy requirement is very critical for nutritional management in patients undergoing major surgery such as pancreatic cancer or esophageal cancer , because over feeding has been associated with some clinical complications . from our findings ,
the stress factor of patients undergoing pppd should be set at 1.2 in patients without major complications .
this factor was compatible to that of patients undergoing esophageal cancer surgery reported by sato et al .
although one would be more likely to find stress - induced hypermetabolism on the earlier postoperative days , the increase in the mree of patients undergoing an esophagectomy was almost the same as during the first seven days . recently
in particular , infection control has been advanced , and may prevent infection induced sirs in the patients undergoing major surgery . in this study , a significant change in the nprq after pppd was not observed . in previous reports ,
this fact means that the energy substrate of the remnant liver is principally fatty acids rather than glucose after a liver resection . in patients undergoing pppd , however ,
glucose is mainly utilized after the surgery as well as in patients undergoing an esophagectomy . in conclusion , patients undergoing pppd have a hyper - metabolic status just after surgery , and the mree / pree ratio was significantly increased to 1.16 . from our results , the daily energy requirements for patients undergoing pppd are recommended at 30  kcal / body weight ( mree 25.7  kcal    3.5  kcal / kg
 we measured the energy expenditure weekly in patients undergoing a pylorus preserving pancreatoduodenectomy for bile duct cancer or pancreatic tumors . 
 twelve patients ( 5 women and 7 men ; mean age 70.1 years ) were enrolled in this study , and their resting energy expenditure levels were determined by indirect calorimetry . in these patients , a significant correlation was observed between the measured resting energy expenditures and the predicted resting energy expenditures calculated by the harris - benedict equation . 
 the resting energy expenditures measured before surgery were almost the same as the predicted resting energy expenditures ( measured resting energy expenditure : 22.4    3.9  kcal / kg / day vs predicted resting energy expenditure : 21.7    2.0  kcal / kg / day ) . 
 the measured resting energy expenditure / predicted resting energy expenditure ratio , which reflects the stress factor , was 1.02    0.10 . 
 after the pylorus preserving pancreatoduodenectomy , a significant increase in energy expenditure was observed , and the measured resting energy expenditure was 25.7    3.5  kcal / kg / day on postoperative day 7 and 25.4    4.9  kcal / kg / day on postoperative day 14 . 
 the measured resting energy expenditure / predicted resting energy expenditure ratio was 1.16    0.14 on postoperative day 7 , and 1.16    0.18 on postoperative day 14 respectively . in conclusion , patients undergoing a pylorus preserving pancreatoduodenectomy showed a hyper - metabolic status as evaluated by their measured resting energy expenditure / predicted resting energy expenditure ratio . from our observations , we recommend that nutritional management based on 30  kcal / body weight / day ( calculated by the measured resting energy expenditureactivity factor 1.21.3 ) may be optimal for patients undergoing a pylorus preserving pancreatoduodenectomy . 
Introduction
Subjects and Methods
Patients
Indirect calorimetry
Statistical analyses
Results
Discussion