Baseline Characteristics
A total of 70 patients were initially recruited for the study. Of these patients, 60 completed the study and were included in the statistical analysis finally. Ten patients were ineligible because they did not meet the inclusion criteria or dropped out (Fig. 1). The baseline clinical data of the two groups are summarized in Table 1. There was no significant difference between the two groups in gender, age, BMI, comorbidities, ASA and Charlson index (all p > 0.05).
Characteristics
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
Table 1
Baseline characteristics of the patients.
Age (yr)
|
70.3 ± 6.5
|
71.0 ± 6.2
|
0.686 ϕ
|
Sex, male, n (%)
|
22 (73.3)
|
21 (70)
|
0.774 $
|
Weight (kg)
|
59.4 ± 7.3
|
58.2 ± 10.2
|
0.582 ϕ
|
Height (cm)
|
164.7 ± 6.2
|
163.9 ± 7.6
|
0.632 ϕ
|
BMI (kg/m2)
|
22.0 (19.6, 23.5)
|
21.6 (18.7, 24.4)
|
0.636 ¥
|
Ideal body weight (kg)
|
62.3 ± 5.6
|
61.0 ± 7.2
|
0.425 ϕ
|
ASA physical status, n (%)
|
|
|
0.292 $
|
II
|
10 (33.3)
|
14 (46.7)
|
|
III
|
20 (66.7)
|
16 (53.3)
|
|
Charlson index
|
6(5, 7)
|
6(5, 7)
|
0.694 ¥
|
Type of surgery, n (%)
|
|
|
1.000 #
|
Gastrectomy
|
21 (70)
|
21 (70)
|
|
Colon surgery
|
3 (10)
|
3 (10)
|
|
Rectal surgery
|
6 (20)
|
6 (20)
|
|
Comorbidity, n (%)
|
|
|
|
Cancer
|
30 (100)
|
30 (100)
|
1.000 #
|
Hypertension
|
10 (33.3)
|
12 (40)
|
0.592 $
|
Diabetes
|
6 (20)
|
5 (16.7)
|
0.739 $
|
Cardiovascular
|
2 (6.7)
|
1 (3.3)
|
1.000 $
|
Neurologic
|
4 (13.3)
|
4 (13.3)
|
1.000 $
|
Respiratory
|
2 (6.7)
|
4 (13.3)
|
0.667 $
|
Kidney
|
4 (13.3)
|
0 (0)
|
0.121 #
|
Liver
|
2 (6.7)
|
4 (13.3)
|
0.667 $
|
Hemoglobin, g/L
|
11.6 (10.1, 12.4)
|
10.5 (9.1, 11.9)
|
0.074 ¥
|
Note: Values are expressed as mean ± SD, medium (IQR), or number (%). ϕ Independent t test was used. ¥ Mann–Whitney U test was used. $ Pearson χ 2 test was used. # Fisher's exact test was used. |
Abbreviations: BMI, body mass index. ASA, American Society of Anesthesiologists.
Intraoperative parameters
As shown in Table 2, the duration of operation, anesthesia, mechanical ventilation and PACU between the two groups were comparable. Likewise, total fluid replacement, urine volume, dosage of propofol and remifentanil, and utilization rate of vasoactive drugs were not different between the two groups(all p>0.05).
Table 2. Intraoperative parameters.
Variables
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
Surgery duration (min)
|
130.5 (120,160)
|
128.5 (120, 170)
|
0.899 ¥
|
Anesthesia duration (min)
|
157.5 (140, 180)
|
150 (138, 185)
|
0.673 ¥
|
Mechanical ventilation time (min)
|
179.5 (166.5, 212.5)
|
175 (155, 214)
|
0.784 ¥
|
PACU (min)
|
45 (35, 60)
|
49.5 (43, 57.25)
|
0.481 ¥
|
Cumulative fluid volume (ml)
|
1850 (1675, 2125)
|
1750 (1600, 1925)
|
0.152 ¥
|
Urine volume (ml)
|
225 (200, 425)
|
200 (137.5, 300)
|
0.129 ¥
|
Propofol (mg)
|
583.6 (472,742.4)
|
571.4 (488.7, 749.7)
|
0.923 ¥
|
Remifentanil (ug)
|
1129.5 ± 389.0
|
1228.2 ± 373.4
|
0.321 ϕ
|
Patients requiring vasopressors, n (%)
|
11 (36.7)
|
12 (40)
|
0.791 $
|
Ephedrine
|
8 (26.7)
|
7 (23.3)
|
0.766 $
|
Phenylephrine
|
4 (13.3)
|
8 (26.7)
|
0.333 $
|
Noradrenaline
|
0 (0)
|
1 (3.3)
|
1.000 #
|
Note: Values are expressed as mean ± SD, medium (IQR), or number. ϕ Independent t test was used. ¥ Mann–Whitney U test was used. $ Pearson χ 2 test was used. # Fisher's exact test was used.
Abbreviations: PACU, post-anesthesia care unit.
Primary Outcomes
There was no statistical difference in lactate level between the two groups before fluid therapy. After infusion, lactate level in the LRS group increased while decreased in the BRS group, and the difference between the two groups was statistically significant at 1 hour after the start of surgery and at the end of operation (p<0.05). Additionally, the incidence of hyperlactacemia occurred in 3.3% (1/30) of the patients in the BRS group versus 40.0% (12/30) of the LRS patients (Table 3, Figure 2).
Table 3. Primary outcomes.
Time
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
Lactate
|
mmol/L
|
|
< 0.001
|
T0
|
1.58 ± 0.61
|
1.47 ± 0.50
|
0.446
|
T1
|
1.19 ± 0.35* #
|
1.85 ± 0.60* #
|
< 0.001
|
T2
|
1.00 ± 0.30* #
|
1.89 ± 0.49* #
|
< 0.001
|
Hyperlactacemia, n (%)
|
1 (3.3)
|
12 (40.0)
|
0.002
|
Note: Values are expressed as mean ± SD or number (%). Bonferroni’s post hoc test was performed for each time point.
Abbreviations: T0, before fluid therapy. T1, 1 hour after the start of surgery. T2, end of the surgery.
# stands for differences between groups, * stands for between-group differences in baseline.
Secondary outcomes
Other arterial blood gas analysis parameters including pH, bicarbonate and BE concentration had no statistical significance at any time points and were within the normal range, so as the hemodynamics (all p>0.05, Table 4).
Patients had similar plasma biochemical parameters (Na+, K+, Mg2+, ALB, TBIL, ALT and AST) between the two groups before infusion (all p >0.05). Of note, AST and ALT increased in the LRS group over 24 h after fluid resuscitation than before (Table 5).
In terms of postoperative gastrointestinal function recovery, the difference was not significant between the two groups (p>0.05). Four (13.3%) versus ten (33.3%) patients developed major complications in the BRS group and LRS group, respectively (p = 0.127). In the LRS group, 1 patient developed multiple major complications died on the 30th day after surgery, 2 patients with two complications, one with pneumonia and stroke, and the other with anastomotic fistula and peritonitis, while 1 patient with anastomotic fistula and stroke in the BRS group, all recovery after treatment. And the major complications in the BRS group mainly occurred one week after surgery, while in the LRS group may occur within two weeks after surgery (Figure 3). As for minor complications, the incidence of wound bleeding and new impaired liver function in the BRS group was significantly lower than that in the LRS group, and the incidence of paralytic ileus was high in both groups. Moreover, preoperative hemoglobin and albumin showed no difference before inclusion, but intraoperative and postoperative total amount of red blood cells and albumin infusion was statistically lower in BRS group( p<0.05). Length of stay in hospital was 9 days (8-11.25) in the BRS group and 11.5 days (9-15.25) in the LRS group (p = 0.012, Table 6).
Table 4. PH, bicarbonate, BE, MAP, HR, SVV were compared between the two groups at different time points.
Time
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
PH
|
|
|
0.582
|
T0
|
7.43 ± 0.07
|
7.45 ± 0.07
|
0.228
|
T1
|
7.39 ± 0.04*
|
7.39 ± 0.07*
|
0.963
|
T2
|
7.36 ± 0.04*
|
7.36 ± 0.05*
|
0.690
|
Bicarbonate
|
mmol/L
|
|
0.958
|
T0
|
24.9 ± 3.7
|
25.6 ± 3.1
|
0.465
|
T1
|
25.6 ± 2.6
|
25.3 ± 3.0
|
0.644
|
T2
|
25.6 ± 2.8
|
25.2 ± 2.8
|
0.569
|
BE
|
|
|
0.707
|
T0
|
0.52 ± 4.04
|
1.45 ± 2.98
|
0.317
|
T1
|
0.59 ± 2.39
|
0.05 ± 2.62*
|
0.408
|
T2
|
0.16 ± 2.42*
|
-0.93 ± 2.29*
|
0.077
|
MAP
|
mmHg
|
|
0.469
|
T0
|
96.3 ± 9.7
|
101.0 ± 15.1
|
0.157
|
T1
|
87.6 ± 12.7*
|
90.1 ± 16.8*
|
0.518
|
T2
|
97.2 ± 16.2
|
96.2 ± 18.9
|
0.821
|
HR
|
bmp
|
|
0.976
|
T0
|
73 ± 12
|
73 ± 14
|
0.881
|
T1
|
68 ± 12
|
65 ± 12*
|
0.373
|
T2
|
68 ± 13
|
71 ± 16
|
0.509
|
SVV
|
%
|
|
0.643
|
T0
|
12.61 ± 3.10
|
14.03 ± 2.96
|
0.783
|
T1
|
7.85 ± 3.70*
|
7.71 ± 2.63*
|
0.829
|
T2
|
7.49 ± 2.74*
|
6.92 ± 2.28*
|
0.651
|
Note: Values are expressed as mean ± SD or number (%). Bonferroni’s post hoc test was performed for each time point.
Abbreviations: T0, before fluid therapy. T1, 1 hour after the start of surgery. T2, end of the surgery.
# stands for differences between groups, * stands for between-group differences in baseline.
Table 5. Electrolytes levels and plasma biochemical parameters were compared between the two groups at different time points.
Time
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
Na+
|
mmol/L
|
|
0.619
|
T0
|
138.6 ± 5.1
|
137.3 ± 2.3
|
0.219
|
T3
|
135.8 ± 4.0*
|
136.3 ± 2.0
|
0.519
|
T4
|
136.1 ± 2.9*
|
135.8 ± 2.4*
|
0.609
|
K+
|
mmol/L
|
|
0.900
|
T0
|
3.92 ± 0.31
|
3.87± 0.35
|
0.600
|
T3
|
4.04 ± 0.31*
|
4.03 ± 0.29*
|
0.897
|
T4
|
4.11 ± 0.39*
|
4.14 ± 0.32*
|
0.779
|
Mg2+
|
mmol/L
|
|
0.441
|
T0
|
0.91 ± 0.07
|
0.91 ± 0.07
|
0.985
|
T3
|
0.89 ± 0.07
|
0.86 ± 0.08*
|
0.098
|
T4
|
0.93 ± 0.08
|
0.93 ± 0.08
|
0.861
|
ALB
|
g/L
|
|
0.825
|
T0
|
40.5 ± 8.4
|
40.4 ± 6.4
|
0.964
|
T3
|
32.3 ± 3.4*
|
33.4 ± 5.8*
|
0.376
|
T4
|
36.3 ± 4.1*
|
35.9 ± 3.5*
|
0.695
|
TBIL
|
umol/L
|
|
0.109
|
T0
|
12.5 ± 5.9
|
13.3 ± 5.1
|
0.564
|
T3
|
11.0 ± 6.0
|
13.6 ± 10.3
|
0.231
|
T4
|
13.2 ± 5.2
|
16.9 ± 10.2*
|
0.085
|
ALT
|
U/L
|
|
0.102
|
T0
|
16 ± 10
|
18 ± 13
|
0.404
|
T3
|
26 ± 24
|
38 ± 29*
|
0.082
|
T4
|
28 ± 21*
|
35 ± 33*
|
0.324
|
AST
|
U/L
|
|
0.242
|
T0
|
20 ± 10
|
21 ± 14
|
0.917
|
T3
|
31 ± 24
|
39 ± 29*
|
0.279
|
T4
|
24 ± 13
|
29 ± 21*
|
0.257
|
Note: Values are expressed as mean ± SD or number (%). Bonferroni’s post hoc test was performed for each time point.
Abbreviations: T0, before fluid therapy.T3, one day after surgery. T4, one week after surgery. ALB, albumin. TBIL, total bilirubin. ALT, alanine transaminase. AST, aspartate aminotransferase.
# stands for difference between groups, * stands for between-group differences in baseline.
Table 6. Postoperative recovery profile.
Variables
|
BRS (n = 30)
|
LRS (n = 30)
|
p-value
|
Time (days)
|
|
|
|
Intestinal exhaust time
|
4 (3, 5)
|
4 (3, 5.25)
|
0.182 ¥
|
Defecating time
|
6 (4, 7)
|
5 (4, 6.25)
|
0.434 ¥
|
Soft diet time
|
6 (4.5, 7)
|
6 (5, 7)
|
0.642 ¥
|
Major complications, n (%)
|
4 (13.3)
|
10 (33.3)
|
0.127 $
|
Anastomotic leakage
|
1
|
5
|
0.197 $
|
Peritonitis
|
0
|
2
|
0.472 #
|
Sepsis
|
0
|
1
|
1.000 #
|
Reoperation
|
0
|
2
|
0.472 #
|
Pulmonary embolism
|
0
|
0
|
-
|
Pulmonary edema
|
0
|
0
|
-
|
Pneumonia
|
2
|
5
|
0.421 $
|
Deep venous thrombosis
|
1
|
0
|
1.000 #
|
Acute coronary syndrome
|
0
|
0
|
-
|
Arrhythmia
|
0
|
1
|
1.000 #
|
Stroke
|
1
|
1
|
1.000 $
|
Acute kidney injury
|
0
|
0
|
-
|
Mortality
|
0
|
1
|
1.000 #
|
Minor complications, n (%)
|
28 (93.3)
|
30 (100)
|
0.150 $
|
Superficial wound infection
|
0
|
0
|
-
|
Urinary and other infection
|
2
|
0
|
0.472 #
|
Paralytic ileus
|
26
|
27
|
1.000 $
|
Wound bleeding
|
3
|
11
|
0.033 $
|
Need for loop diuretics
|
0
|
0
|
-
|
POD
|
1
|
1
|
1.000 $
|
PONV
|
9
|
11
|
0.584 $
|
Cough and expectoration
|
8
|
14
|
0.108 $
|
Impaired liver function
|
5
|
15
|
0.006 $
|
Pruritus
|
1
|
2
|
0.472 $
|
Blood component transfusion, n (%)
|
16 (53.3)
|
22 (73.3)
|
0.108 $
|
RBC (units)
|
0 (0, 0)
|
0 (0, 3)
|
0.021 ¥
|
FFP (units)
|
0 (0, 0)
|
0 (0, 325)
|
0.102 ¥
|
ALB (g)
|
10 (0, 60)
|
35 (0, 80)
|
0.040 ¥
|
Length of hospital stay (days)
|
9 (8, 11.25)
|
11.5 (9, 15.25)
|
0.012 ¥
|
Note: Values are expressed as median (IQR) or number (%). ¥ Mann–Whitney U test was used. $ Pearson χ 2 test was used. # Fisher's exact test was used.
Abbreviations: POD, postoperative delirium. PONV, postoperative nausea and vomiting. RBC, red blood cells. FFP, fresh frozen plasma. ALB, albumin.
6