Comparison of development of postoperative cognitive dysfunction using different methods of anesthesia in elderly patients

Abstract

Objective To compare the development of postoperative cognitive dysfunction (POCD) under total inhalation anesthesia with sevoflurane versus total intravenous anesthesia with propofol in elderly patients. Methods Sixty American Society of Anesthesiologists physical status Ⅱ or Ⅲ patients, aged 65-77 yr, weighing 43-78 kg, with preoperative Mini-Mental State Examination (MMSE) score≥25, scheduled for elective surgery for oral and maxillofacial carcinoma, were divided into 2 groups (n=30 each) using a random number table: total inhalation anesthesia with sevoflurane group (group S) and total intravenous anesthesia with propofol-based anesthesia group (group P). The patients were tracheally intubated under local infiltration anesthesia.In group S, anesthesia was induced with inhalation of 8% sevoflurane (oxygen flow rate 8 L/min), rocuronium 0.9 mg/kg was injected intravenously when the bispectral index (BIS) value reached 45, and the patients were mechanically ventilated; anesthesia was maintained with inhalation of sevoflurane with the end-tidal concentration of 2%-3%.In group P, anesthesia was induced with iv propofol 2 mg/kg and sufentanil 0.3 μg/kg, rocuronium 0.9 mg/kg was injected intravenously when the BIS value reached 45, and the patients were mechanically ventilated; anesthesia was maintained with target-controlled infusion of propofol (target plasma concentration 3-5 μg/ml) and remifentanil (target plasma concentration 3-5 ng/ml). In both groups, intermittent iv boluses of cisatracurium 0.04 mg/kg were given to maintain muscle relaxation during operation, and BIS value was maintained at 40-60 during operation.Before intubation (T1), immediately after onset of intubation (T2), at 10 min of intubation (T3), immediately after begninning of skin incision (T4), while operating on the base of tongue or sawing the lower jaw (T5), at the end of operation (T6) and on the morning of the postoperative day 1 (T7), blood samples from the elbow vein were collected for determination of plasma norepinephrine and epinephrine concentrations by high-performance liquid chromatography and electrochemistry.At T1-7 and on the morning of the postoperative day 3 (T8), blood samples from the elbow vein were collected for measurement of plasma cortisol concentrations by radioimmunoassay.MMSE was used to assess the cognitive function on the postoperative day 7.MMSE score < 24 was defined as POCD, and the occurrence of POCD was recorded. Results Compared with group S, the plasma concentrations of norepinephrine and epinephrine were significantly decreased at T4 and T5, the plasma cortisol concentration was significantly decreased at T4-7 (P 0.05). Conclusion Although the probability of the development of POCD is low when the two anesthetic methods are used, total intravenous anesthesia with propofol-based anesthesia induces a marked decrease in perioperative stress responses when compared with total inhalation anesthesia with sevoflurane. Key words: Anesthesia, intravenous; Anesthesia, inhalation; Propofol; Anesthetics, inhalations; Aged; Cognition disorders; Stress