Impact of Anesthesia Maintenance Methods on Incidence of Postoperative Delirium
Condition: Delirium; Postoperative Complications; Postoperative Cognitive Dysfunction
MeSH terms: Delirium; Emergence Delirium; Postoperative Complications; Postoperative Cognitive Complications; Cognitive Dysfunction
Study type: Interventional

Summary: 
      Surgery is one of the major treatment methods for patients with malignant tumor. And, alone
      with ageing process, more and more elderly patients undergo surgery for malignant tumor.
      Evidence emerges that choice of anesthetics, i.e., either inhalational or intravenous
      anesthetics, may influence the outcome of elderly patients undergoing cancer surgery.
      Delirium is a commonly occurred early postoperative cognitive complication in the elderly,
      and its occurrence is associated with the worsening outcomes. Choice anesthetics may
      influence the occurrence of postoperative delirium. However, evidence in this aspect is
      conflicting.
    

Detailed description: 
      It is estimated that 234.2 million major surgical procedures are undertaken every year
      worldwide. Surgery is one of the major treatment methods for patients with malignant tumor.
      And, alone with ageing process, more and more elderly patients undergo surgery for malignant
      tumor. Evidence emerges that choice of anesthetics, i.e., either inhalational or intravenous
      anesthetics, may influence the outcome of elderly patients undergoing cancer surgery.

      Delirium is a commonly occurred cognitive complication in elderly patients after surgery. The
      occurrence of delirium is associated with the worsening outcomes, including increased
      morbidity and mortality, prolonged hospital stay, elevated medical care cost, and declined
      cognitive function. High age, major surgery, and critical illness are major risk factors of
      postoperative delirium (POD). However, the relationship between use of general anesthetics
      and occurrence of delirium cannot be excluded.

      There are studies that compared the effects of two kinds of anesthetics on the cognitive
      outcomes after surgery. In the study of Nishikawa et al., 50 elderly (≥ 65 years) patients
      undergoing long-duration laparoscope-assisted surgery randomly received sevoflurane or
      propofol anesthesia. The results showed that, although the incidence of POD was not
      significantly different between the two groups, the delirium rating scale (DRS) score was
      significantly lower in the sevoflurane group than in the propofol group at postoperative days
      2-3 (P = 0.007 and 0.002, respectively). In the study of Schoen et al., 128 patients
      undergoing on-pump cardiac surgery were randomized into two groups. The results showed that
      early postoperative cognitive function was significantly better in sevoflurane group than in
      the propofol group, especially in those who experienced cerebral desaturation during surgery.

      On the other hand, some studies reported contrary results. In a large sample size study of
      2000 patients undergoing general anesthesia, patients carrying ApoE4 epsilon 4 allele were
      more likely to develop early postoperative cognitive decline after inhalational anesthesia
      (odd ratio 3.31, 95% confidence interval 1.25-6.39, P < 0.05), but not after intravenous
      anesthesia (odd ratio 0.93, 95% confidence interval 0.37-2.39, P > 0.05). In a randomized
      control trail of 44 patients undergoing carotid endarterectomy, the mini-mental state
      examination (MMSE) score was significantly higher, whereas blood S100B concentration was
      significantly lower in the propofol group than in the sevoflurane group at 24 hours after
      surgery. In the study of Tang et al., 200 elderly (≥ 60 years) patients with mild cognitive
      impairment who planned to undergo radical rectal resection randomly received either
      sevoflurane or propofol anesthesia. The results showed that, although there was no difference
      in the incidence of cognitive dysfunction at 7 days after surgery, the negative cognitive
      effects was more severe after sevoflurane anesthesia than after propofol anesthesia (P =
      0.01).

      It seems that more evidence suggests the harmful cognitive effects of inhalational
      anesthetics. However, care must be taken when explaining these results: (1) target patients
      population were different; (2) sample size were small in the majority of studies; (3) the
      diagnostic criteria of cognitive complications were different, make it hard to do
      meta-analysis; (4) the clinical significance the of early postoperative cognitive
      complication remains to be elucidated.
    

Intervention name(s): Sevoflurane; Propofol
Intervention type(s): Drug; Drug
Intervention description(s): Sevoflurane will be administered by inhalation for anesthesia maintenance. The concentration of inhaled sevoflurane will be adjusted to maintain the bispectral index (BIS) value between 40 and 60. Analgesia will be supplemented with remifentanil (administered by continuous infusion), sufentanil (administered by intermittent injection/continuous infusion), or fentanyl (administered by intermittent injection).
Towards the end of surgery, sevoflurane inhalational concentration will be decreased and fentanyl/sufentanil will be administered when necessary. Sevoflurane inhalation will be stopped at the end of surgery.; Propofol will be administered by intravenous infusion for anesthesia maintenance. The infusion rate of propofol will be adjusted to maintain the BIS value between 40 and 60. Analgesia will be supplemented with remifentanil (administered by continuous infusion), sufentanil (administered by intermittent injection/continuous infusion), or fentanyl (administered by intermittent injection).
Towards the end of surgery, propofol infusion rate will be decreased and fentanyl/sufentanil will be administered when necessary. Propofol infusion will be stopped at the end of surgery.
Other intervention name(s): Sevoflurane for inhalation; Propofol for injection
Intervention MeSH terms: Propofol; Sevoflurane
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Sevoflurane; Propofol; Aged; Neoplasm; Surgical Procedure, Operative; Delirium; Postoperative Complications; Postoperative Cognitive Dysfunction