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. 2018 Aug 21;2018(8):CD012317. doi: 10.1002/14651858.CD012317.pub2

Tanaka 2017.

Methods RCT, parallel design, single‐centre
Participants Total number of randomized participants: 100
Inclusion criteria

  1. > 65 years of age, scheduled for TKA, ASA II or III, BMI > 30 kg/m2


Exclusion criteria

  1. Refusal of or failure of regional block

  2. Pre‐existing neurocognitive disorders (MMSE ≤ 23)

  3. Known intolerance to any of drugs used in the study


Type of surgery: total knee arthroplasty
Baseline characteristics
TIVA group

  1. Age, mean (SD): 71 (± 5.8) years (taken from clinical trials register documents)

  2. Gender, M/F: 16/34 (taken from clinical trials register documents)

  3. ASA grade: ASA II: 22; ASA III: 23 (calculated from study report for 45 participants)


Inhalational maintenance group

  1. Age, mean (SD): 70 (± 4.0) years (taken from clinical trials register documents)

  2. Gender, M/F: 29/21 (taken from clinical trials register documents)

  3. ASA grade: ASA II: 26; ASA III: 19 (calculated from study report for 45 participants)


Country: US
Setting: hospital
Interventions TIVA group
Participants: n = 50; 11 losses (3 withdrawn; other reasons include early hospital discharge, oversedation, respiratory distress, PONV, and pain ‐ not reported by group); 39 analysed
Induction details: femoral nerve block with initial bolus of 30 mL 0.25% ropivacaine as well as placement of indwelling catheter. Sedation with fentanyl and midazolam provided for femoral nerve block at discretion of regional anaesthesia team. Induction with propofol 1 mg/kg, fentanyl 1 µg/kg to 2 µg/kg, rocuronium 0.4 mg/kg, all dosed according to lean body weight
Maintenance details: propofol. Use of Sedline to maintain PSI 30 to 50
Other information: after surgery, a continuous infusion of 0.2% ropivacaine at 6 mL/hour was initiated in recovery room and adjusted to maximum of 10 mL/hour for next 48 hours. PCA device to administer IV hydromorphone with standardized dosing and lock‐out period
Inhalational maintenance groups
Participants: n = 50; 10 losses (1 withdrawn; other reasons include early hospital discharge, oversedation, respiratory distress, PONV, and pain ‐ not reported by group); 40 analysed
Induction details: femoral nerve block with initial bolus of 30 mL 0.25% ropivacaine as well as placement of indwelling catheter. Sedation with fentanyl and midazolam provided for femoral nerve block at discretion of regional anaesthesia team. Induction with propofol 1 mg/kg, fentanyl 1 µg/kg to 2 µg/kg, rocuronium 0.4 mg/kg, all dosed according to lean body weight
Maintenance details: desflurane. Use of Sedline to maintain PSI 30 to 50
Other information: after surgery, a continuous infusion of 0.2% ropivacaine at 6 mL/hour was initiated in recovery room and adjusted to maximum of 10 mL/hour for next 48 hours. PCA device to administer IV hydromorphone with standardized dosing and lock‐out period
Outcomes

  1. Postoperative delirium (using CAM) at baseline 1, 6, 24 and 48 hours after surgery

  2. Cognitive function (20% decrease from baseline to indicate cognitive decline) using DSST (day 1), Digit Span (day 2), and Trail Making Test (part A and part B; day 2)

  3. Wake‐up times

  4. Length of stay in PACU

  5. Pain scores

  6. PONV


Note: we interpreted bar charts provided by study authors (from email communication) for cognitive function tests. In meta‐analysis, we used data for Trail Making part A.
Notes Funding/declarations of interest: research grant from Baxter Healthcare Corporation
Study dates: October 2010 to August 2014
Note: all participants are obese
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk Use of computer‐generated random numbers
Allocation concealment (selection bias) Unclear risk No details
Blinding of participants and personnel (performance bias) 
 All outcomes High risk Not feasible to blind anaesthetists to intervention groups
Blinding of outcome assessment (detection bias) 
 All outcomes Low risk Nurses who administered CAM assessment were blinded
Incomplete outcome data (attrition bias) 
 All outcomes High risk Study authors do not report reasons for losses by each group, and data is reported inconsistently between clinical trials register documents and published study report. Overall losses are high
Selective reporting (reporting bias) High risk Retrospectively registered with clinical trials register (NCT01270620). Not feasible to assess risk of selective reporting bias from this document. However, we noted that MMSE was an outcome in the methods section of the published report but was not reported in results. In addition, we noted a difference in data for postoperative delirium, and length of stay was reported for a different number of participants. Overall, we judged risk of selective reporting bias as high
Other bias Unclear risk We noted a difference in gender balance between groups; unclear if this is clinically important