The Effects On Oxygen Delivery-consumption Balance Of Suxamethonium And Rocuronium During The Induction Of Anesthesia In The Elderly

Object:Some studies indicate that suxamethonium can increase the oxygen consumption of brain, and easier cause the brain oxygen delivery-consumption unbalance. Rocuronium dose not cause it. But there is no study of the effects for body oxygen delivery-consumption balance of them, especially in rapid sequence induction phase.Because the reasons of age, the organs of body appear retrograde degeneration in the elderly, the tissues oxygen storage decreased and easier cause oxygen delivery-consumption unbalance during anesthesia period. Oxygen delivery-consumption unbalance can increase the ratio of complication and mortality in per-operative period, so it is important in maintaining the oxygen delivery-consumption balance of senile patient. The rapid sequence induction has more chance to disturb the physiological mechanism of senile patient, and must pay attention to oxygen delivery-consumption balance of the elderly. So it has magnitude sense in select the appropriate neuromuscular blocking agent to maintain the oxygen delivery-consumption balance of senile patient.Mixed venous oxygen saturation (SVO2) and concentration of lactic acid (Lac) are reliable and sensitive indexes to the changes of body oxygen delivery-consumption balance, combine analyze them can reflect the change of tissues oxygen intaking. SvC>2 was affected by the relation of body oxygen delivery-consumption, cardiac output, hemoglobin concentration (Hb) and so on. SvO2 upward means the body oxygen delivery increased and (or) oxygen consumption decreased, it downward means the body oxygen delivery decreased and (or) oxygen consumption increased. Lactic acid is the outcome of tissues cells anaerobic metabolism, and it is an index imaging anaerobic metabolism. Lac upward means anaerobic metabolism enhance and downward means reduce. Some studies have proved the pertinence of right atrial blood oxygen saturation (RASyC^) and SvC>2 is very nice. Davies GG detected with 464 paired data in swine that the difference between the overall means of RASyO2 and SvO2 was 0.91% with a standard error of the estimate of 4.7%, a regression equation is RASvO2 = 0.94 SvO2 + 2.1, and a correlation coefficient is 0.94. The changes of RASyC^ can credibility reflect the change of SVO2. Therefore, we can make use of RASvO2 and Lac to reflect the change currents of body oxygen delivery-consumption balance.This investigation simulates the rapid sequence induction phase of the eldly, observes the variety of blood-gas indexes and the concentrations of lactic acid of right atrial blood that effect by suxamethonium and rocuronium, discuss the influence of body oxygen delivery-consumption balance, guide the choose of neuromuscular blocking agent in general anesthesia rapid sequence induction phase. Method:1. Case selection and grouping: 36 senile patients, 60 to 70 years, ASA I or II and no disease of heart, lung, brain, liver and kidney, distribute randomly into three groups: suxamethonium group (S group, n=12), rocuronium group (R group, n=12)and control group (C group, n=12). Register gender, age, weight and hemoglobin concentration of 36 patients.2. Anesthesia method and measure: Routine prohibit drink and food at 12 hours pre-operative and intramuscular diazepam 10 mg and atropine 0.5 mg at 30-minute pre-operative for all of patients. All of patients intravenous drip Ringer's solution, the drip transfusion velocity is lOml/min.Then place BRAUN central venous catheters via right internal jugular vein with local anesthesia and use the right atrial electrocardiography-guided technique to confirm the location of the catheter tip within the right atrium (after the upright P wave become large and tine, then readvance 0.5cm-1.0cm and P wave become light biphasic). Note the depth of central venous catheter and perfect moor it to collect blood sample subsequently. The induction of anesthesia start after 30 minutes of intravenous drip and use fentanyl 2ug/kg and propofol 2mg/kg for inducement. After consciousness disappeared and respiration is restrained, close veil tightly and ventilate to get rid of nitrogen and fill in oxygen, tidal volume is lOml/kg, respiratory rate is 15 pre-minute and inspiratory time: expiratory time ratio is 1: 2. Then inject suxamethonium 2mg/kg in S group, rocuronium 0.6mg/kg in R group and no drug in C group by intravenation. Thereafter, stop ventilate 5 minutes simulate no ventilation in period of endotracheal intubation. Simultaneity, continue measure mean artery blood pressure (MAP), heart rate (HR), pulse oxygen saturation (SpO2) and electrocardiogram.3. Collect and measure blood sample: Six injectors, each abstract right atrium blood 2ml at pre- anesthesia (To), pre-injection of neuromuscular blocking agent (Ti) and post- injection of neuromuscular blocking agent lmin (T2), 2 min (T3), 3 min (T4), 5 min (T5). The injectors must be heparinized with heparin 125 unit before collect blood samples, and rubber must block syringe needle after the collection to avoid the coagulation and oxidation of blood samples. The blood samples must be measured theindex of blood-gas by Rapidlab 845 blood-gas analyzer and concentration of lactic acid by I-STAT blood-gas analyzer within 30 minutes.4. Statistical analysis: Using SPSS 10.0 (Statistical Package for Social Sciences 10.0) to analysis the data. Measurement data expressed with Mean ± Standard deviation (x+s). Main effect and interaction of each index use analysis of variance (ANOVA) of repeated measures data, interclass effect and interaction use ANOVA of single variable (one-way ANOVA) and do multiple comparisons among each time point. Count data use nonparametric test. P < 0.05 means statistically significant. Results:1. The sexuality, age, weight and hemoglobin concentration is no statistically significant among three groups (P > 0.05).2. The average depth of central venous catheters is 16.72+0.503cm.3. MAP. HRandSpO2:? The main effect and interaction of MAP> HR and SpO2 is no statistically significant among three groups (P > 0.05).(2) Interclass effect and interaction we can observe that MAP decreased significantly at Ti, T2, T3, T4, T5 compare with To. But compare with Ti, MAP and HR is no significant change at T2, T3, T4, T5.(3) All of the SpO2 over 90% at each time point in three groups.4. Blood-gas and concentration of lactic acid:(D The main effect and interaction of RASvO2, Lac, right atrial blood oxygen partial pressure (RAPvO2), right atrial blood carbon dioxide partial pressure (RAPvCO2) and pH is no statistically significant among three groups (P > 0.05).(2) Interclass effect and interaction we can observe that compare with Ti, RASvO2 and Lac increased significantly at T2, T3, T4 in S group (P < 0.05);RASvO2 increased significantly at T2 and Lac is no significant change in R group (P < 0.05);RASVO2 and Lac are no significant change in C group. RAPvCO2 increased significantly and pH decreased significantly at T2, T3, T4 and T5 compare with Ti (P < 0.05). Conclusion:1. For senile patients of ASA I or II, the effects of homodynamic are gentle by suxamethonium or rocuronium; the changes of homodynamic are caused by fentanyl and propofol during rapid sequence induction period.2. RASvO2, Lac and RAPVO2 are no significant change among three groups means either suxamethonium or rocuronium cannot cause evidence change of blood-gas index during rapid sequence induction period.3. Stop ventilate 5 minutes after get rid of nitrogen and fill in oxygen 1 minute cannot cause hypoxia of senile patients of ASA I or II, but the concentration of CO2 in blood increase significantly.4. Compare with Ti, RASVO2 and Lac increased significantly at T2, T3, T4 in S group, RASvC>2 increased significantly at T2 and Lac is no significant change in R group and RASvO2 and Lac are no significant change in C group. This means both suxamethonium and rocuronium can decrease body oxygen consumption of senile patients. But suxamethonium can enhance anaerobic metabolism of tissues, easier cause body oxygen delivery-consumption unbalance. Rocuronium also decrease body oxygen consumption, but cannot enhance anaerobic metabolism, is propitious to maintain the body oxygen delivery-consumption balance of senile patients.5. There is no significant relation between the changes of homodynamic and the decrease of body oxygen consumption caused by suxamethonium and rocuronium.