Effect of infusion and withdrawl of glucose and insulin on gas exchange in injured ventilated patients.
OBJECTIVE
To evaluate the effect induced on gas exchange and on urea excretion by glucose and insulin infusion in injured patients. The magnitude and time necessary for the full development of the metabolic effect were investigated.


METHODS
Six injured patients were investigated. During the first 24 hours, the fasting period, patients received 1 mg/kg*min of glucose; during the second 24 hours, the treatment period, infusion was increased to about the 95% of the energy production rate; during the last 8 hours, (stop period) the infusion rate was again set to 1 mg/kg*min. Gas exchange was determined in two consecutive 12-hour series, for 30 minutes every hour, either during a stabilized treatment or after its variation. Urea excretion was determinated on 4-hour samples.


RESULTS
With respect to the fasting period, during the last 4 hours of the treatment period, the energy production rate did not vary; urea excretion (-25%) and oxygen consumption (-9%) decreased significantly. Carbon dioxide production (+16%), total respiratory quotient, and minute ventilation (+5%) increased significantly. Carbon dioxide production varied linearly with time (glucose infusion +1.74 mL/min*m2*h, P < .05; glucose withdrawal -1.89 mL/min*m2*h, P < .01). Minute ventilation decreased only during the withdrawal period by 65 mL/min*m2*h (P < .05).


CONCLUSIONS
The infusion of glucose and insulin, in an amount slightly lower than the metabolic expenditure, leads to a consistently reduced amino acid catabolism and to a decreased oxygen consumption, without affecting energy requirements. Although it leads to an increase of carbon dioxide production, the measured change is so small and slow that it is not harmful unless there is severe respiratory insufficiency.
Radrizzani
D
D
Intensive Care Unit E. VECLA, IRCCS Ospedale Maggiore di Milano, Italy.
Iapichino
G
G
Colombo
A
A
Codazzi
D
D
Pasetti
G
G
Ronzoni
G
G
Savioli
M
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D003422:Critical Care; D004734:Energy Metabolism / Q000187:drug effects; D005215:Fasting / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D006801:Humans; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011659:Pulmonary Gas Exchange / Q000187:drug effects*; D012121:Respiration, Artificial; D013997:Time Factors; D014947:Wounds and Injuries / Q000378:metabolism / Q000628:therapy*
D007328:Insulin; D005947:Glucose