A survey for sudden hepatic artery haemorrhage

Twenty-one attending surgeons from our general surgery department were invited to participate in the survey. The first question concerned how many surgeries they had performed that required hepatic artery dissection or lymphadenectomy around the hepatic artery. One attending surgeon had performed 0 − 50 cases, two surgeons had performed 50 − 100 cases, six surgeons had performed 100 − 200 cases, eleven surgeons had performed 200 − 500 cases, and one surgeon had performed more than 500 cases (Fig. 1A). The second question addressed whether they had ever experienced hepatic artery haemorrhage during such surgeries. Eighteen surgeons reported having experienced hepatic artery haemorrhage (Fig. 1B). The third question asked how many patients experienced hepatic artery haemorrhage. Eleven surgeons had dealt with 10–20 cases, seven surgeons had dealt with 5–10 cases, and three surgeons had dealt with 0–5 cases. The fourth question concerned the artery that as more likely to suffer haemorrhage during surgery, with options including the common hepatic artery (CHA), hepatic artery proper (HAP), right hepatic artery (RHA), and left hepatic artery (LHA) (Fig. 1C). Most surgeons (18/21) believed that HAP was more prone to injury (Fig. 1E). The fifth question addressed the direction in which the HAP haemorrhage was more likely to have occurred from the injury (Fig. 1D). Three surgeons thought it occurred in the 0 − 3 o’clock direction, seven surgeons thought it occurred in the 3 − 6 o’clock direction, five surgeons thought it occurred in the 6 − 9 o’clock direction, and six surgeons thought it occurred in the 9 − 12 o’clock direction (Fig. 1F).

Fig. 1

A survey of 21 attending surgeons in the general department of Sir Run Run Shaw hospital. (A) Surgical number statistics of operations that require hepatic artery dissection or lymphadenectomy around the hepatic artery. B Statistics for the surgeons who encountered hepatic artery haemorrhage in such surgeries. C Surgical number statistics for hepatic artery haemorrhage in such surgeries. D Representation of different regions of the hepatic artery and different locations of the HAP. E Statistics for different regions of the hepatic artery that are more easily to be injured. F Statistics for different locations of the HAP which that are more easily to be injured

Bleeding speed

Based on the survey, the bleeding hole designed on the HAP of our model was located at approximately the 4 o’clock position. Ten models were randomly selected, and the statistics for blood loss within one minute were obtained. The one-minute blood loss was 14 ml for the seven models; it was 15 ml for the remaining three models. Overall, our model demonstrated good consistency in terms of bleeding speed (Supplementary Fig. 1C).

Baseline characteristics of the participants

Baseline characteristic data of the participants were collected and analysed (Table 1). All the surgeons in the three groups were male. The age of the surgeons was significantly higher in Group A than in Group F (38.0 ± 1.6 vs. 32.8 ± 1.3, p < 0.001), and it was significantly higher in Group F than in Group R (32.8 ± 1.3 vs. 29.0 ± 1.6, p = 0.003). The number of working years was significantly longer in Group A than in Group F (11.8 ± 2.2 vs. 6.0 ± 1.2, p = 0.001), and it was significantly longer in Group F than in Group R (6.0 ± 1.2 vs. 3.0 ± 0.7, p = 0.001). The number of laparoscopic cholecystectomies (LCs) completed was significantly larger in Group A than in Group F (p = 0.008), and it was significantly larger in Group F than in Group R (p = 0.008).

Table 1 Baseline characteristics of these 3 groupsFirst training assessment

The performances of the three groups are presented in Table 2. The operation time was significantly shorter in Group A than in Group F (267.2 ± 67.8 s vs. 434.4 ± 71.3 s, p = 0.005), whereas it was significantly shorter in Group F than in Group R (267.2 ± 67.8 s vs. 675.4 ± 127.0 s, p = 0.006). The amount of blood loss was significantly reduced in Group A than in Group F (57.0 ± 17.7 ml vs. 104.4 ± 19.1 ml, p = 0.004), whereas the operation time was significantly shorter in Group F than in Group R (104.4 ± 19.1 ml vs. 164.0 ± 33.1 ml, p = 0.008). The goal score was significantly higher in Group A than in Group F (20.8 ± 1.6 vs. 16.8 ± 1.8, p = 0.006), whereas it was significantly higher in Group F than in Group R (16.8 ± 1.8 vs. 11.8 ± 1.9, p = 0.003). The repair score and narrowness score were higher in Group A but lower in Groups F and R. Arterial narrowing after the operation is also shown in Supplementary Fig. 2.

Table 2 Operation performance in these 3 groupsEight time training assessments

Two surgeons each in Group F and Group R, who had sufficient time, were invited to receive a total of eight training sessions for laparoscopic hepatic artery repair. One fellow surgeon (F2) and one resident surgeon (R1) each has one failed operation because the wall of the hepatic artery was torn during suturing. The operation times, blood loss rates and goal scores of these eight training sessions from the 4 surgeons are shown in Fig. 2A-C. Basically, as the number of training sessions increased, the required operation time and surgical blood loss decreased, whereas the goal score increased. As the number of training sessions increased, the repair score and narrow score also gradually improved (Fig. 2D, E).

Fig. 2

Operation performances for trainers in eight time sessions are shown; surgeons performed better after repeated training (the “fail” marking in the figure indicates a failed surgery due to a serious hepatic artery wall tear). A The operation time curve for the four trainers in the eight time trainings. B Blood loss curve for the four trainers in the eight time trainings. C Goal score curve for the four trainers in the eight time trainings. D Repair score histogram for the four trainers in the eight time trainings. E Narrow score histogram for the four trainers in the eight time trainings

Analysis of clinical hepatic arterial haemorrhage and suggestions for repair

The 21 attending surgeons were invited to describe the most likely cause of hepatic arterial haemorrhage in the survey. Eight attending surgeons mentioned heat damage or other damage caused by the ultrasonic knife (including false aneurysms), 7 surgeons mentioned injury caused by arterial anatomical variation or small branching, 6 surgeons mentioned that the anatomic hierarchy was misjudged, 1 surgeon mentioned poor visibility, and 1 surgeon mentioned that an assistant surgeon may not cooperate well (Fig. 3A). These surgeons were also asked to provide some surgical suggestions for laparoscopic hepatic artery repair (one surgeon could provide more than one suggestion). Eighteen surgeons suggested blood flow control, including blocking bands, pressure haemostasis, and titanium clips, to temporarily control bleeding. Ten surgeons suggested further dissection to identify the exact location of bleeding and then to perform the repair. Seven surgeons emphasised clearing accumulated blood and maintaining a clear line of vision, and 7 surgeons emphasised using Prolene for suturing (Fig. 3B). In our training sessions on the hepatic artery haemorrhage model, we also found that experienced surgeons seemed to pay more attention to clearly exposing the bleeding spot before performing accurate suturing (Supplementary Fig. 3A). During the procedure, dissection forceps might be used more often to block the hepatic artery to reduce blood loss (Supplementary Fig. 3B). After suturing, they were more inclined to strain the suture to see if the repair was satisfactory before knotting (Supplementary Fig. 3C).

Fig. 3

A continued survey of 21 attending surgeons from the general department of Sir Run Run Shaw hospital. A Statistics for the surgeons’ opinion about the most likely cause of hepatic artery haemorrhage. B Statistics for the surgeons’ recommendations on how to better manage hepatic artery bleeding

Simulation model evaluation

The five attending surgeons recruited in the first training session were also invited to evaluate the authenticity of this hepatic artery haemorrhage model. The results are shown in Table 3. Most indicators, including visual size, elasticity, sense of breakthrough upon sewing, bleeding scene simulation and sense of urgency for operators, were given high scores, which indicated that the five senior surgeons were relatively satisfied with these aspects of the model. The score for ease of tear (3.80 ± 1.30) was lower, which indicated that the artery wall might be easier to tear.

Table 3 Authenticity evaluation of the model by five attendingsForce test

The mechanical values of hepatic artery tearing in 3D printed silicone models and isolated swine hepatic arteries were tested via the wearable knot tying force test platform (Fig. 4A). Three 3D printed models were randomly selected for testing. The external figure-of-8 suture method using 6–0 Prolene was utilised for the hepatic artery repair (Fig. 4B). The mechanical critical values of hepatic artery tears were 1.589 N, 1.790 N and 1.792 N, and the average mechanical strength was 1.724 N (Fig. 4C). Three isolated swine hepatic arteries were tested using the same suture method (Fig. 4D). The hepatic artery from the isolated swine did not tear before the Prolene broke. The mechanical values of the 6–0 Prolene fractures in the three tests were 3.489 N, 3.355 N and 3.041 N, respectively, and the average mechanical strength was 3.295 N (Fig. 4E).

Fig. 4

Mechanical value test for the hepatic artery wall in the 3D printed model and isolated swine organ. A A wearable knot tying force test platform consisting of a knob, two pulleys, a slider, a steel wire, and a load cell was constructed to accurately measure the tension in sutures during surgical suturing process. B An external figure-of-8 suture method using 6–0 Prolene was used for the hepatic artery repair, and the mechanical value of the hepatic artery wall tear was measured using the force test platform. C Three 3D printed models were randomly selected for testing, and the mechanical critical values of the hepatic artery tears are presented. D Three isolated swine organs were selected for testing and the mechanical critical values of the hepatic artery tears are presented. E The hepatic artery from the isolated swine did not tear before the Prolene broke. The mechanical values of the 6–0 Prolene fractures are presented