Effects Of Low-dose Dopamine On Acid-base Balance In Patients Undergoing Gastrointestinal Surgery During General Anesthesia

Objective To investigate the effects of low-dose dopamine on acid-base balance in patients undergoing gastrointestinal surgery during general anesthesia.Methods Sixty patients with ASA physical status I? III, male or female, aged 18 ? 65 years, scheduled for elective gastrointestinal surgery, were randomized into two groups: control group?Group C, n=30? and dopamine group?Group D, n=30?. Group C was not given infusion of dopamine during the operation, while Group D received continuous infusion of low-dose dopamine 1?2?g·kg^-1·min^-1 by micro pump via internal jugular vein after anesthesia induction until the end of surgery. The two groups both adopted intravenous anesthesia, and the ways of anesthesia induction and maintenance were identical. The changes of arterial blood gas indexes?p H, BE, HCO₃^-, PaCO₂?, Lac, HR, MAP, CVP, BIS and axillary temperature were recorded before anesthesia induction?T₀?, 1 hour?T₁?, 2 hours?T₂? and 3 hours?T₃? after anesthesia induction, and 30 min after the operation?T₄?. The urine output, volume of blood loss, crystal, colloid, blood transfusions, and case-times of ephedrine, urapidil, atropine and sodium bicarbonate injection during the operation were recorded.Results?1? There was no significant difference in general information between the two groups of patients?P> 0.05?.?2? Comparison of arterial blood gas indexes and arterial blood lactic acid between the two groups: inter-group comparison showed that p H, BE and HCO₃^-were higher and Lac was lower at T₁?T₄ in Group D than Group C?P< 0.05?. Comparison of p H, BE, HCO₃^-and Lac at T₀ between the two groups: the differences in PaCO₂ at T₀?T₄ between the two groups were not statistically significant?P > 0.05?. Intra-group comparison showed that p H, BE and HCO₃^-were lower and CVP was higher at T₁?T₄ than T₀ in both groups, and the changes were more significant in Group C than Group D?P<0.05?; the differences in PaCO₂ at T₁?T₄ between the two groups were not statistically significant?P> 0.05?.?3? Comparison of HR, MAP and CVP between the two groups: inter-group comparison showed that MAP was higher at T₁?T₄ in Group D than Group C?P< 0.05?, while CVP was lower at T₃?T₄ in Group D than Group C?P < 0.05?. Comparison of HR at T₀? T₄ between the two groups: inter-group comparison showed that there were no statistically significant differences in MAP at T₀ and CVP at T₀?T₂ between the two groups?P> 0.05?. Intra-group comparison showed that MAP was lower and CVP was higher at T₁?T₄ than T₀ in both groups, and the changes were more significant in Group C than Group D?P< 0.05?; HR was lower at T₂?T₃ in both groups?P< 0.05?, and HR was also lower at T₁ and T₄, but the differences were not statistically significant?P>0.05?.?4? Comparison of BIS and axillary temperature between the two groups: the differences in BIS and axillary temperature at T₀?T₄ between the two groups were not statistically significant?P> 0.05?.?5? Comparison of fluid intake and output and medications between the two groups during the operation: the urine output was increased more significantly in Group D than Group C?P< 0.05?, while the case-times of ephedrine and sodium bicarbonate injection were reduced in Group D compared with Group C?P< 0.05?. Comparison of intraoperative volume of blood loss, crystal, colloid and blood transfusions and case-times of urapidil and atropine between the two groups showed no statistically significant differences?P> 0.05?.Conclusion Low-dose dopamine can increase urine output, reduce arterial blood lactic acid levels, contribute to acid-base balance stability and keep hemodynamics stable in patients undergoing gastrointestinal surgery during general anesthesia.