3.1 Baseline Data
We recruited 12 swine for this study while one swine in the control groups was excluded because major bleeding occurred during puncture due to carotid artery tortuosity. Eventually, eleven swine were included in the final sample. All the general physiological conditions were statistically similar between the two groups in T1, including weight (14.08±1.28kg VS 14.10±0.10kg, P=0.541), SP (121.17±11.51mmHg VS 118.40±12.34mmHg, P=0.710), DP (91.50±12.05mmHg VS 87.80±15.55mmHg, P=0.712), HR (80.83±6.11bpm VS 82.40±4.28bpm, P=0.642), abdominal aortic diameter (0.69±0.05cm VS 0.65±0.06cm, P=0.475), and the maximum depth of the anechoic zone in the abdominal cavity (0.07±0.08cm VS 0.12±0.13cm, P=0.230). Detailed statistics are reported in Table 1.
Table 1. Sample characteristics at baseline (Mean±SD).
Group
|
Number
|
Weight (kg)
|
Abdominal Aortic Diameter (cm)
|
Systolic Pressure (mmHg)
|
Diastolic Pressure (mmHg)
|
Heart Rate (bpm)
|
Maximum Depth of Anechoic Zone (cm)
|
Intervention group
|
6
|
14.08±1.28
|
0.69±0.05
|
121.17±11.51
|
91.50±12.05
|
80.83±6.11
|
0.07±0.08
|
Control group
|
5
|
14.10±0.10
|
0.65±0.06
|
118.40±12.34
|
87.80±15.55
|
82.40±4.28
|
0.12±0.13
|
T values
|
|
0.024
|
1.144
|
0.384
|
0.381
|
0.481
|
0.830
|
P values
|
|
0.541
|
0.475
|
0.710
|
0.712
|
0.642
|
0.230
|
3.2 Analyzing the factors in the intervention group
During the process to establish the model, hemorrhagic shock appeared in the intervention group after puncturing the right iliac artery. Including BP fell from 121.17±11.51mmHg at T1 to 83.00±16.64mmHg at T2 (P =0.000), DP fell from 91.50±12.05mmHg at T1 to 60.17±16.76mmHg at T2 (P =0.000), HR increased from 80.83±6.11bpm at T1 to 101.50±5.39bpm at T2 (P =0.000), and the maximum depth of anechoic zone in the abdominal cavity increased from 0.07±0.09cm at T1 to 2.32±0.25cm at T2 (P =0.000). After measurement was done at T2, we performed REBOA under portable ultrasound guidance. SP and DP increased to 97.17±11.92 mmHg (T2 vs T3, P =0.040) and 66.67±12.34mmHg ( T2 vs T3, P=0.214) at T3 respectively. HR and the maximum depth of the anechoic zone increased to 111.83±7.39bpm (T2 vs T3, P =0.001) and 3.10±0.41cm (T2 vs T3, P =0.001) at T3. Then, SP, DP, and HR became stable in T4 at 97.50±9.29mmHg (T3 vs T4, P =0.846), 67.67±10.78mmHg (T3 vs T4, P =0.518), and 113.83±5.49bpm (T3 vs T4, P =0.352), respectively. Yet the maximum depth of the anechoic zone in the abdominal cavity slightly increased to 3.50±0.36cm at T4 (T3 vs T4, P =0.000). Detailed statistics are reported in Tables 2 and 3.
3.3 Analyzing the factors in the control group
Hemorrhagic shock also appeared in the control group after establishing the model. BP fell from 118.40±12.34mmHg at T1 to 85.40±13.65mmHg at T2 (P =0.000), DP fell from 87.80±15.55mmHg at T1 to 56.20±7.40mmHg at T2 (P =0.004), HR increased from 82.40±4.28bpm at T1 to 103.20±3.70bpm at T2 (P =0.000), and the maximum depth of anechoic zone in the abdominal cavity increased from 0.12±0.13cm at T1 to 2.46±0.25cm at T2 (P =0.000). After performing extracorporeal compression by gauze locally, SP kept falling to 71.20±6.18mmHg at T3 (T2 vs T3, P =0.016), and then to 62.40±3.44 mmHg at T4 (T3 vs T4, P =0.003). Similarly, DP decreased to 43.80±5.63mmHg at T3 (T2 vs T3, P =0.000), and further to 35.00±3.39mmHg at T4 (T3 vs T4, P =0.001). HR increased significantly to 122.00±4.53bpm at T3 (T2 vs T3, P =0.000) and then to 132.40±3.98 bpm at T4 (T3 vs T4, P =0.000). The maximum depth of the anechoic zone kept increasing to 4.12±0.24cm at T3 (T2 vs T3, P =0.000) and further to 5.14±0.35cm at T4 (T3 vs T4, P =0.000). Detailed statistics are reported in Tables 2 and 3.
3.4 Analyzing the factors between groups
The RMANOVA of SP revealed a main effect of group (F = 5.732, P = 0.040), a main effect of test time (F = 145.103, P = 0.000), and a significant group * test time interaction (F = 34.081, P = 0.000). For DP, it indicated a main effect of group (F = 6.547, P = 0.031), a main effect of test time (F =89.259, P = 0.000), and a significant group * test time interaction (F = 16.121, P = 0.000). For HR, it indicated a main effect of group (F =7.419, P = 0.023), a main effect of test time (F =549.658, P = 0.000), and a significant group * test time interaction (F = 26.597, P = 0.000). And for the maximum depth of the anechoic zone, it also indicated a main effect of group (F =27.742, P = 0.000), a main effect of test time (F =976.212, P = 0.000), and a significant group * test time interaction (F = 40.568, P = 0.000). Detailed statistics are reported in Tables 2 and Fig. 5.
Table 2. The changes in hemodynamic and physiological parameters in the intervention group and control group at different times.
Group/time
|
Systolic Pressure (mmHg)
|
Diastolic Pressure (mmHg)
|
Heart Rate (bpm)
|
Maximum Depth of Anechoic Zone (cm)
|
Intervention group
|
|
|
|
|
T1
|
121.17±11.51
|
91.50±12.05
|
80.83±6.11
|
0.07±0.09
|
T2
|
83.00±16.64
|
60.17±16.76
|
101.50±5.39
|
2.32±0.25
|
T3
|
97.17±11.92
|
66.67±12.34
|
111.83±7.39
|
3.10±0.41
|
T4
|
97.50±9.29
|
67.67±10.78
|
113.83±5.49
|
3.50±0.36
|
Control group
|
|
|
|
|
T1
|
118.40±12.34
|
87.80±15.55
|
82.40±4.28
|
0.12±0.13
|
T2
|
85.40±13.65
|
56.20±7.40
|
103.20±3.70
|
2.46±0.25
|
T3
|
71.20±6.18
|
43.80±5.63
|
122.00±4.53
|
4.12±0.24
|
T4
|
62.40±3.44
|
35.00±3.39
|
132.40±3.98
|
5.14±0.35
|
Time (P values) [Time (F values )]
|
0.000*
[145.103]
|
0.000* [89.259]
|
0.000*
[549.658]
|
0.000*
[976.212]
|
Group (P values) [Group (F values)]
|
0.040*
[5.732]
|
0.031*
[6.547]
|
0.023*
[7.419]
|
0.000*
[27.742]
|
Time * Group (P values)
[Time * Group (F values)]
|
0.000*
[34.081]
|
0.000*
[16.121]
|
0.000*
[26.597]
|
0.000*
[40.568]
|
The asterisk (*) represents significant differences at p < 0.05.
T1: at baseline, T2: free bleeding for the 30s, T3: bleeding for 10min, T4: bleeding for 30min.
Table 3. Compared with the previous time point in the within-group by using one-way ANOVAs.
Group/P values
|
Systolic Pressure (mmHg)
|
Diastolic Pressure (mmHg)
|
Heart Rate (bpm)
|
Maximum Depth of Anechoic Zone (cm)
|
Intervention group
|
|
|
|
|
P (T1 vs T2)
|
0.000*
|
0.000*
|
0.000*
|
0.000*
|
P (T2 vs T3)
|
0.040*
|
0.214
|
0.001*
|
0.001*
|
P (T3 vs T4)
|
0.846
|
0.518
|
0.352
|
0.000*
|
Control group
|
|
|
|
|
P (T1 vs T2)
|
0.000*
|
0.004*
|
0.000*
|
0.000*
|
P (T2 vs T3)
|
0.016*
|
0.000*
|
0.000*
|
0.000*
|
P (T3 vs T4)
|
0.003*
|
0.001*
|
0.000*
|
0.001*
|
The asterisk(*) represents significant differences at p < 0.05.
T1: at baseline, T2: free bleeding for the 30s, T3: bleeding for 10min, T4: bleeding for 30min.
3.5 Ultrasound Manifestation
During the process to establish the model, the artery rapidly collapsed with less blood flow and the inner diameter of the artery decreased in the ultrasound image after the puncture of the iliac artery. Color Doppler ultrasound showed that the iliac vein was compressed and there was no blood flow signal (Fig. 6).
In the intervention group, we placed the balloon catheter from the left iliac artery to the lower abdominal aorta under ultrasound guidance. Once the balloon was inflated(Video2), the blood flow in the distal abdominal aorta and iliac artery were significantly reduced or disappeared by color Doppler ultrasound. (Video3, Fig. 7). Via the Doppler spectrum, we verified that the aorta had occluded with the balloon completely. As the balloon inflated, the ultrasound images clearly showed that the maximum depth of the anechoic zone in the abdominal cavity increased slower in the intervention group than in the control group (Fig. 8).
3.6 Pathologic finding
After the animals were sacrificed and the abdominal was opened, huge blood clots in the abdominal and retroperitoneum were visible. The gross pathological finding confirmed the rupture of the right iliac artery (Fig. 9). We measured total blood loss by quantifying blood clots and blood absorbed by the gauze. The total blood loss of the intervention group and the control group was 1245.23±190.07g and 2605.63±291.67g respectively. The difference between the two groups was statistically significant (T=6.768, P=0.002). However, on pathologic assessment, there was not a significant difference in the muscle tissue of both the intervention group and the control group in T1 and T4 (Fig. 10).