Traumatic stress and clinical advantages of laparoscopic and open gastric bypass surgery

**Fundamental Differences**

Understanding the fundamental differences between laparoscopic and open surgery is crucial for comprehending the differences in clinical outcomes between the two types of bariatric surgery. The primary differences lie in the incision length, exposure method, and degree of trauma. Open RYGB typically uses a midline upper abdominal incision, while laparoscopic RYGB uses 5-6 small abdominal punctures. Open surgery usually uses abdominal wall retractors and mechanical retractors to expose abdominal organs, while laparoscopic surgery creates pneumoperitoneum to create operating space and uses gravity to reposition intra-abdominal organs for exposure. Because of the shorter incision length and the elimination of mechanical traction required for exposing the abdominal wall and organs, we believe that laparoscopic RYGB is significantly less traumatic than open surgery. However, the pressure effect of pneumoperitoneum and the use of carbon dioxide in laparoscopic surgery can lead to changes in intraoperative physiological functions. Carbon dioxide absorption in pneumoperitoneum can cause hypercapnia and respiratory acidosis. Furthermore, when intra-abdominal pressure reaches 15 mmHg during surgery, it can have certain effects on internal organs such as the lungs, heart, and kidneys.

**Important Evaluation Indicators**

When comparing the outcomes of a surgical procedure performed using two different techniques, it's crucial to identify which indicators should be evaluated. These indicators can be assessed from several different perspectives, including those of surgeons, healthcare administrators, and patients. Surgeons tend to evaluate specific indicators such as operative time, length of hospital stay, and complication rates; healthcare administrators focus on clinical efficacy, length of hospital stay, quality of care, and medical costs; and patients are more concerned with the treatment process, postoperative pain/discomfort, and recovery time. With so many clinical outcome indicators available, it is particularly important for researchers to select the best indicators and to evaluate them correctly. While opinions may differ on how to choose indicators, it is crucial to apply the evaluation results to guide clinical practice and decision-making.

Some commonly used efficacy indicators include operative time and hospital stay. While shorter operative times are generally preferred, using them as the sole evaluation indicator does not accurately reflect the effectiveness of the surgery. Similarly, hospital stay can be misleading, as it only represents the time from treatment to the patient's safe discharge. However, taking cholecystectomy as an example, although patients undergoing laparoscopic cholecystectomy and open cholecystectomy can be discharged at the same time, there are differences in their physical experience. Laparoscopic patients often experience few or no symptoms after discharge, while open patients may experience postoperative pain, difficulty moving, and discomfort.

Other efficacy indicators include postoperative pain and recovery period length. Postoperative pain is multifactorial, but one important factor is the size of the surgical trauma; generally, minor surgeries result in less postoperative pain than major surgeries. Postoperative recovery is also a very effective efficacy indicator; generally, minor surgeries recover faster than major surgeries. There are various methods for quantifying recovery time and recovery type, the most common being the time required to recover to the point of being able to perform daily activities and the time required to recover to the point of being able to return to work. The time required to return to work is usually inaccurate because it is based on the patient's wishes; some patients may choose to postpone their return to work even after they have regained their ability to do so. The time required to return to daily activities is a better indicator than the former, but it is still relatively subjective and does not specify a particular type of activity. Therefore, more specific evaluation indicators for assessing the recovery to daily activities should be used, including physical strength, social skills, sexual function, and self-evaluation of physical health. Another important efficacy indicator is the severity of surgical trauma; one reason why laparoscopic bariatric surgery has better postoperative efficacy compared to open bariatric surgery is that it involves less surgical trauma.

**Effectiveness of Clinical Comparison**

A comparison between laparoscopic and open bariatric surgery is only meaningful when the two surgical methods are similar and the surgeons are highly experienced. Therefore, the equivalence and validity of the comparison should be considered. For example, in early laparoscopic bariatric surgery, surgeons often did not suture mesenteric gaps, leading to postoperative bowel obstruction. This prompted the current practice of suturing all mesenteric gaps in laparoscopic bariatric surgery. Laparoscopic bariatric surgery is more complex; therefore, for a meaningful comparison, the surgeon should be proficient in laparoscopic techniques. A prospective randomized study by Westling and Gustavsson compared laparoscopic and open bariatric surgery, showing no statistically significant difference in postoperative pain, hospital stay, and recovery time. In their study of 51 patients, 30 underwent laparoscopic bariatric surgery and 21 underwent open surgery. Seven patients (23% of those who underwent laparoscopic surgery) subsequently switched to open surgery during the laparoscopic procedure. This result indicates that laparoscopic weight loss surgery requires a high level of technical skill. Therefore, when comparing laparoscopic and open weight loss surgeries, laparoscopic surgeons should already possess proficient laparoscopic operating skills.

Every laparoscopic surgery has a learning curve. However, laparoscopic bariatric surgery is more challenging than some other advanced laparoscopic surgeries. If we were to rate the difficulty of laparoscopic techniques, with 1 being the easiest and 10 the most difficult, the authors would rate laparoscopic bariatric surgery as a 9. Unlike laparoscopic cholecystectomy, laparoscopic bariatric surgery requires surgeons to be familiar with intestinal transection and reconstruction techniques, as well as to perform a significant amount of suturing.

**Physiological Basis for Improved Efficacy of Laparoscopic Bariatric Surgery**

The primary improvement in postoperative efficacy of laparoscopic bariatric surgery is its reduced trauma. As the abdominal incision (skin, fascia) widens and lengthens, and intra-abdominal organs are stretched, surgical trauma increases accordingly. However, it is difficult to quantify the degree of trauma between laparoscopic and open gastric bypass surgery. Previously, the degree of trauma could be indirectly quantified by measuring the amount of third-space fluid accumulation after the two surgical methods. Surgical trauma often leads to edema, known as third-space fluid, and its volume often corresponds to the extent of surgical trauma. Third-space fluid accumulation can be indirectly measured by measuring intra-abdominal pressure. The abdominal cavity is a single cavity; therefore, postoperative intra-abdominal tissue and intestinal wall edema, intestinal distension, and intra-abdominal hemorrhage can all be reflected in intra-abdominal pressure. Measurements of bladder pressure (indirectly reflecting intra-abdominal pressure) revealed that intra-abdominal pressure was lower in patients after laparoscopic gastric bypass surgery than in patients after open surgery on the first, second, and third days postoperatively. Furthermore, intra-abdominal pressure in the laparoscopic group returned to normal on the second postoperative day, while intra-abdominal pressure in the open surgery group remained higher than normal even on the third postoperative day.

Another method for assessing the severity of surgical trauma is to examine the patient's postoperative systemic stress response. The level of stress response is correlated with the severity of surgical trauma. Interleukin-6 (IL-6) is a non-specific pro-inflammatory cytokine, and its expression level is correlated with the degree of surgical trauma. Previous studies have shown that postoperative IL-6 expression levels in the laparoscopic group were significantly lower than those in the open group, indicating that laparoscopic surgery is less invasive than open gastric bypass surgery, which is also an advantage of laparoscopic surgery over open surgery.