The Effects Of Ropivacaine Administered Epidurally On Neuromuscular Blockade Of Cisatracurium In Geriatric Patients

ObjectiveThe objective of this subject is to observe the effects of ropivacaine administered epidurally on the neuromuscular blockade of cisatracuruim in the elderly patients, and provide the evidence for clinical medication.MethodsFifty patients aged 60~85years, ASA gradeⅠ~Ⅲ, scheduled for elective non-laparoscopic abdominal surgery with combined general and epidural anesthesia were enrolled. All the patients were distributed into GEA group and GA group randomly according to whether administered ropivacaine epidurally.All the patients were premedicated with scopolamine 0.3mg i.m. 30 min before entering the operation room. On arrival at the operating room, vital signs of the patients were monitored. Lactated Ringer's solution was infused intravenously at a rate of 7~10 ml·kg-1·h-1 via a cannula in the left fore arm. With the left lateral decubitus position, epidural puncture was performed at T10-11 intervertebral space routinely. The epidural catheter was inserted and introduced 3cm cephalad. A dose of 3 ml of 0.75% ropivacaine was given as a test dose in the patients of GEA group. After tested the sensory level to ruled out that the catheter was at the subarachnoid cavity, the patients in GEA group received a loading dose of 0.75% ropivacaine to maintian the maxlmum of the sensory level stayed at T6. A supplementary dose of 3~5ml of 0.75% ropivacaine was given about 60min after the bolus every 60~80min. The same volume of saline as ropivacaine in GEA groups was given in the GA group.General anaesthesia induction was started with midazolam 0.06 mg·kg-1, fentanyl 4μg·kg-1, etomidate 0.2mg·kg-1 sequentially 15min after administration of the loading dose of ropivacaine. After loss of consciousness of the patients, TOF-Wacth SX acceleromyography was used to calibation and set the control value. Intubation was performed when the T1 was lower than 5%Tc. A propofol infusion at the rate of 3~8 mg·kg-1·h-1 and a sufentanil infusion at the rate of 0.2~1μg·kg-1·h-1 by the microinfusion pump was followed to maintain BIS value was between 40~50. The SBP and HR fluctuations in the basic value of 20%. When T1 had recovered to 25%Tc, the infusion of cisatracurium was started at the rate of 3μg·kg-1·min-1. The infusion rate was adjusted gradually 0.1~0.2μg·kg-1·min-1 up and down every time to maintain T1 stayed at the neuromuscular block level of 10%Tc. The infusion of sufentanil was stopped 20min before the termination of the surgery. The infusion of cisatracurium was stopped at the closure of abdominal cavity. Propofol was stopped infusing at the termination of the surgery.The following variables were observed, including some general indicators : hemodynamics, dosages of each drug, intubation conditions and adverse reaction; the indicators measuring the neuromuscular blockade for the bolus dose of cis-atracurium:⑴Lag Time (sec) from the time of bolus injection of cis-atracurium to the beginning of depression of T1;⑵Onset Time (sec) from the injection of cis-atracurium to maximum depression of T1;⑶Peak Time (min) from the maximum depression to T1 recover to 5%Tc;⑷Clinical Duration (min) from the bolus injection of cisatracurium to spontanous recovery of T1 25%Tc; and the recovery indicators for the maintaining dose of cis-atracurium:⑸recovery index (min) time required for spontanous recovery of T1 from 25% to recovery 75%;⑹spontaneous recovery time(min), from the discontinuation of cisatracurium to TOFR recovery to 0.25, 0.5, 0.7 and 0.9.Results1. There was no significant difference in the age, height, weight, BMI, proportion of sex and ASA grade, quantity of bleeding between groups. The duration of anaesthesia and surgery did not differ significantly between groups.2. The value of MAP and HR before intubation were significantly lower than the value before anaesthesia between the two groups (p<0.01 for the comparison of MAP, p<0.05 for the comparision of HR ). The value of MAP and HR at 3min after intubation were significantly higher than the value before intubation in both two groups (p<0.01 for the comparison of MAP, p<0.05 for the comparision of HR ) . The value of MAP and HR at each time did not differ between the two groups.3. The following differences of the neuromuscular blockade had been discovered, including: the lag time was 105.9±20.1sec and 97.1±17.10sec in the GEA group and GA group respectively, and did not differ between the two groups (p> 0.05). The onset time was 322.9±47.6 sec and 298.6±41.2 sec in the GEA group and GA group respectively, and did not differ between the two groups (p> 0.05). However, the peak time in the GEA group(42.8±7.5min) was significantly longer than that of the GA group (33.8±6.3min) (p<0.01). Also, the clinical duration in the GEA group (62.6±8.3min) was significantly longer than that of the GA group(54.8±6.9min) (p<0.01).4. The spontaneous time from the discontinuation of cisatracurium to TOFR recovery to 0.25 , 0.5 , 0.7 and 0.9 was 17.7±3.9min,27.2±4.5min,36.2±5.2min,45.1±6.5min for the GEA group respectively. The spontaneous time from the discontinuation of cisatracurium to TOFR recovery to 0.25 , 0.5 , 0.7 and 0.9 was 15.8±2.6 min,25.5±4.3 min,33.4±5.3min,42.3±7.2 min respectively. There was no differance in each time between GEA group and GA group (p> 0.05). The recover index was 16.7±3.2min in the GEA group and 14.7±1.9 min in the GA group, and did not differ between the two groups(p> 0.05).5. The duration of infusion in the GEA group (89.5±12.9min) was significantly shorter than the duration in the GA group (100.7±14.2min) (p<0.05). The total dosage of cisatracurium in the GEA group (7.91±1.82mg) was significantly lower than the dosage of cisatracurium in the GA group (10.68±2.74 mg) (p<0.05). The average infusion rate of cisatracurium every hour in the GEA group(0.096 mg·kg-1·h-1) was slower than the rate in the GA group (0.109 mg·kg-1·h-1) (p<0.05).6. The requirement of propofol for anaesthesia maintenance was significantly lower in the GEA group (4.17±0.42mg·kg-1·h-1) than that in the GA group (5.21±0.40 mg·kg-1·h-1) (p<0.01). The requirement of sufentanil for anaesthesia maintenance was significantly lower in the GEA group(0.27±0.029μg·kg-1·h-1) than in the GA group (0.32±0.033μg·kg-1·h-1) (p<0.05). The loading dose of 0.75% ropivacaine in the GEA group was 11.1±0.92ml, while the supplementary dose was 8.9±1.86ml.Conclusion1. Routine loading dose of ropivacaine administered epidurally does not influence the onset time of the dose 3×ED95 of cisaracurium, while delays the recovery of the neuromuscular blokcade of this dose of cisatracurium in the elderly patients.2. Routine supplementary dose of ropivacaine administered epidurally does not delay the recovery of cisatracurium when infused to maintain the same neuromuscular blocking level, while reduces the requirement of cisatracurium.3. It is recommended that the monitoring of neuromuscular funtion should be reinforced when cGEA was used in the elderly patients, and adjust the dosage of NMBAs according to the results of the monitoring.