ISSN: 0970-938X (Print) | 0976-1683 (Electronic)

Biomedical Research

An International Journal of Medical Sciences

Abstract

Minimum effective concentration for the inhibitory effect of remifentanil on circulatory response due to pneumoperitoneum during laparoscopic surgery in elderly patients

Objective: To find the minimum effective concentration required by remifentanil to inhibit circulatory response due to pneumoperitoneum during laparoscopic surgery in elderly patients.

Methods: ASA grade I/II patients aged 65-80 years old who received elective laparoscopic colon surgery were selected. All patients received Target-Controlled Infusion (TCI) of propofol, with a target plasma concentration of 3.5 μg/ml. They were administrated with 0.9 mg/kg rocuronium after loss of consciousness, inserted with laryngeal mask 2 minutes later and given plasma TCI with remifentanil before the start of surgery to determine its concentration using the sequential method. If mean arterial pressure and/or heart rate of a previous patient increased by >20% within five minutes after pneumoperitoneum compared with before pneumoperitoneum, the current patient was administered with remifentanil at a higher concentration. If the values increased by <20% within five minutes, the current patient was a lower concentration of remifentanil. The target concentration ratio of adjacent effect-site compartments was 1.2. The TCI target plasma concentration (EC50) of remifentanil for inhibiting the hemodynamic fluctuations of 50% of elderly patients after pneumoperitoneum was calculated using the sequential method.

Results: With the sequential method, EC50 of remifentanil for suppressing the hemodynamic response to laparoscopic pneumoperitoneum was 2.67 ng/ml and the 95% confidence interval was 2.61-2.72 ng/ml.

Conclusion: In combination with propofol during TCI, remifentanil at the target plasma concentration of 2.67 ng/ml can inhibit 50% of elderly patients from circulatory fluctuations caused by laparoscopic pneumoperitoneum.


Author(s): Shaohua Liu, Ming Tian

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