Effects Of The Application Of Tourniquet And Fluid Therapy On Heamodynamics And Metabolism During Operations On Lower Extremity By Combined Spinal And Epidural Anesthesia

Objective To investigate the effects of tourniquet inflation-deflation andfluid therapy on hemodynamics and metabolism of patients undergoinglower extremity orthopedic surgery by combined spinal-epidural anesthesia(CSEA), and compare the benefits and defects of acetated Ringer'ssolution (Plasma-Lyte A) (AR) and lactated Ringer's solution (LR) onmaintaining stability of metabolism of electrolytes and lactate and acid-basebalance during the operation.Methods Thirty ASAâ… -â…¡patients of both sexes (23 males, 7 females)aged 17～63 yes weighing 50～99 kg undergoing lower extremity orthopedicsurgery needing the application of tourniquet were randomly allocated toone of two groups (n=15 each): group A received AR; group L received LR.The crystalloid was infused at a rate of 10ml·kg^-1·h^-1 after the patientsentering the operation rooms; The Polygeline Injection was infused at a rateof 15-20ml·kg·h^-1 in the first 30min after spinal anesthesia; and then thecrystalloid was infused at a rate of 10ml·kg^-1·h^-1. The Polygeline Injectionwas infused at a rate of 20-25ml·kg^-1·h^-1 in the first 30min in the first10min after the release of tourniquet; and then the crystalloid was infusedbased on the amount of blood loss. The SBP, DBP and HR were measuredbefore tourniquet inflation (T0 baseline) and 30,60,90min after tourniquetinflation (INF) (TI30,TI60,TI90) and 1,3,5,10,30min after tourniquetdeflation (DEF) (TD1,TD3,TD5,TD10,TD30). The arterial blood gas lactateconcentration, electrolyte and blood routine were measured at T0,TD5,TD10 and TD30.Results During tourniquet INF,SBP and HR did not changed (P＞0.05),whereas DBP was higher at TI90 than at T0 (group A P＜0.05, group LP＜0.01). After tourniquet DEF,SBP and DBP decreased at 1 and 3 min, andHR increased at 1,3 and 5 min. PaO₂ decreased at 5 and 10 min (TD5P＜0.01, TD10 P＜0.05), and PaCO₂ increased at 5 min (P＜0.01). pH andBE decreased significantly at 5 and 10 min (P＜0.01), and HCO₃^- decreasedonly at 5 min (group A P＜0.05, group L P＜0.01). P₅₀ increased at 5 min(Group A P＜0.01, group L P＜0.05). Arterial blood lactate levels andserum potassium levels were significantly increased at all time-points(P＜0.01). Hemoglobin and hematocrit were decreased at all time-points(P＜0.01). Serum calcium concentration and chlorine concentration ofgroup A was lower at TD30 than the baseline level at T0 (P＜0.01). Serumsodium concentration of group L was lower at TD10 and TD30 than thebaseline level at T0 (TD10P＜0.05,TD30 P＜0.01). Serum chlorineconcentration of LR group was significantly higher at all time-points thanthe baseline level at T0 (P＜0.01). After tourniquet DEF, PaO₂, BE andHCO₃^- of group L decreased more significantly at 5min than that of group A(P＜0.05). pH of group L decreased more significantly at 5,10min than thatof group A (P＜0.01). Arterial blood lactate levels increased moresignificantly at all time-points than that of group A (TD5 and TD 10 P＜0.01,TD30 P＜0.05).Conclusion Adequate analgesia and timely and effective administrationof local anesthetic to the epidural space under CSEA can avoid tourniquetpain which may be caused by the regresses of sensory block level, and inconsequence CSEA is possible to avoid the significant increase of bloodpressure during the inflation of tourniquet. The compensation ability to thehypercapnia is better and the recovery of metabolic variables are morequickly in CSEA when compared to general anesthesia withmechanically-controlled ventilation. So CSEA is available for most people. During the lower extremity orthopedic surgery using a tourniquet,combined application of crystalloid/colloid and appropriate adjustment tothe speed of fluid infusion according to the anesthetic and operative processand the outcome of monitor can maintain steady hemodynamic state duringthe induction and maintain of anesthesia and the tourniquet INF/DEF,ensure the metabolic balance of the tissues and organs, and have a certainvolume expansion and hemodilution effects.Plasma-Lyte A have more powerful acidoresistant capabilitycompared with lactated Ringer's solution, so it is more suitable for thelower extremity orthopedic surgery using a tourniquet for a long time, makethe patients have more compensation ability to the metabolic acidosis whichis caused by the application of tourniquet, and have superiority to stabilizethe physiological internal environment.