Figure 1. Patient recruitment.

Figure 2. Number and percentage of diagnosed delirium pre-operatively and postoperatively in the two groups. For statistical significance, * indicates p ≤ 0.05.

Figure 3. Pre- and postoperative CRP between the two groups. For statistical significance, * indicates p ≤ 0.05. CRP, C-reactive protein.

Table 1. Patient characteristics.

Table 1. Patient characteristics.

Patient CharacteristicSham (n = 70)Hydrogen (n = 83)p_ValueAge (years) (mean ± SD)70.74 ± 5.3970.45 ± 5.200.73Sex (%) Male36(51%)37(44%)0.50Female34(49%)46(56%) Weight (kg) (mean ± SD)67.53 ± 11.8666.94 ± 12.420.77Height (cm) (mean ± SD)165.49 ± 7.99164.41 ± 8.120.41ASA (%) 0.39Ⅱ37(53%)37(44%) Ⅲ33(47%)46(56%) Hgb127.56 ± 14.47127.81 ± 16.070.92PLT215.5 ± 62.27230.06 ± 51.720.12ALB36.87 ± 4.1037.66 ± 3.800.22ALT19.79 ± 16.2218.01 ± 10.020.41AST20.09 ± 9.4518.67 ± 13.200.28GLU5.62 ± 1.355.45 ± 1.510.48Hypertension12(17%)10(12%)0.37Diabetes12(17%)10(12%)0.37

Table 2. Perioperative variables.

Table 2. Perioperative variables.

Sham (n = 70)Hydrogen (n = 83)p_ValueType of surgery orthopedic50(71%)53(63%) abdominal15(21%)18(22%) thoracic5(8%)12(15%) Duration of surgery (min) (mean ± SD)117.77 ± 84.48116.08 ± 50.510.88Total intra-operative infusion (ml) (mean ± SD)1391.43 ± 416.851389.16 ± 434.490.20Urine volume (ml) (mean ± SD)308.57 ± 256.50348.57 ± 287.970.37Bleeding volume (ml) (mean ± SD)154.14 ± 327.5083.72 ± 114.430.07Use of other analgesic during the first 7 postoperative days Morphine (n)1(1%)1(1%)0.90Morphine (mg)1010 Flurbiprofen axetil (n)24(34%)18(21%)0.08Flurbiprofen axetil (mg)104.17 ± 44.03100 ± 34.30.74

Table 3. Effectiveness outcomes.

Table 3. Effectiveness outcomes.

Sham (n = 70)Hydrogen (n = 83)p_ValuePrimary endpoint Overall incidence of delirium17(24%)(95% CI = 1.49 to 1.67)10(12%)(95% CI = 1.18 to 1.57)0.048 *Secondary endpoints Length of stay in the hospital after surgery (day)9.70 ± 2.189.23 ± 1.900.16All-cause 30-day mortality0(0%)0(0%) Prespecified analyses NRS for pain (score) First morning after surgery3.54 ± 1.774.08 ± 1.770.048 *Third morning after surgery2.15 ± 1.112.2 ± 1.100.82Seventh morning after surgery1.06 ± 0.991.08 ± 0.910.84NRS for sleep quality (score) First morning after surgery5.21 ± 1.845.24 ± 1.640.93Third morning after surgery6.11 ± 1.505.95 ± 1.530.50Seventh morning after surgery6.50 ± 1.436.41 ± 1.530.71Exploratory analyses Time to onset of delirium (day)2.29 ± 1.262.45 ± 1.210.74Duration of delirium (day)1.71 ± 0.691.36 ± 0.670.21Haloperidol treatment2(2.8%)3(3.6%)

Table 4. Postoperative adverse effect data.

Table 4. Postoperative adverse effect data.

Sham (n = 70)Hydrogen (n = 83)p_ValueSPO2_PACU < 92% (n)(%)2(3%)6(7%)0.23PONV (n)(%)5(7%)4(5%)0.55Headache (n)(%)0(0%)0(0%) Uroschesis (n)(%)0(0%)0(0%) Bradycardia (n)(%)0(0%)1(1%)0.36Hypotension (n)(%)2(3%)3(4%)0.80Hypertension (n)(%)2(3%)3(4%)0.80