Closed technique for entering the abdominal cavity during laparoscopic weight loss surgery
**Entering the abdominal cavity**
Crystal T. Schlösser, Sayeed Ikramuddin
The inherent advantage of all minimally invasive surgeries is access to body cavities safely, effectively, and cost-effectively. However, access to the abdominal cavity in obese patients is more challenging in bariatric surgery due to patient size, current equipment limitations, and the presence of comorbidities. The ideal goal of abdominal access is to achieve adequate exposure, facilitate instrument insertion and specimen retrieval, and minimize complications.
**background**
The application of pelvic endoscopy first introduced specific limitations regarding access to the peritoneum, peritoneal physiology, and three-dimensional surgery under two-dimensional imaging. Early laparoscopic methods borrowed instruments from urology, obstetrics and gynecology, and thoracic surgery, and employed early pneumoperitoneum needles designed in the 1930s for establishing diagnostic pneumoperitoneum. However, complications from these methods led to the adoption of a traditional small incision approach under direct vision to enter the abdominal cavity, with a large-bore cannula inserted for laparoscopic procedures. Subsequently, both techniques have been developed, resulting in new abdominal access devices that reduce the axial force required to enter the abdominal cavity (spiral devices).
An ideal device for establishing pneumoperitoneum should be simple, quick, and rapidly establish pneumoperitoneum with few (or even no) complications. Ideally, it should be reusable to reduce costs. Currently, there is no ideal device that meets all these requirements, but this is the goal for future research and development.
**Methods of entering the abdominal cavity**
Regardless of the device chosen for access to the abdominal cavity, adhering to basic surgical principles maximizes efficiency and minimizes complications. Careful patient preparation, including positioning the patient in a supine position without tilting, rotation, or head-down positioning, is crucial. Incorrect patient positioning can lead to misinterpretation of the patient's anatomical structure, causing confusion regarding the course of major blood vessels and changes in organ position, resulting in delayed identification and potential unforeseen injuries. During physical examination, attention should be paid to scarring and piercings around the umbilicus or other body parts, as these may be related to intra-abdominal adhesions.
A key consideration in abdominal surgery planning is determining how to maximize the intra-abdominal operating space. Options include standard carbon dioxide pneumoperitoneum, but this can lead to dryness and coldness of the viscera and parietal peritoneum. This is associated with pain (especially diaphragmatic pain), hypothermia, and peritoneal mesothelial cell morphological changes of uncertain significance. Alternative media such as helium and water expansion have been reported. Pneumoperitoneum-free techniques such as abdominal wall traction have also been reported, but none of these are currently suitable for obese surgical patients.
The steps to achieve pneumoperitoneum are: no insufflation, insufflation before insufflation, and insufflation only after an open approach has been established. Intra-abdominal pressure management must be patient-centered; sufficient pressure to achieve good exposure is necessary for surgical safety, but intra-abdominal pressure should also be low enough to avoid ventilation limitations, hypercapnia, and impaired venous return.
**Closed access method to the abdominal cavity**
The pneumoperitoneum needle is a 2mm blunt-tipped needle designed to induce pneumothorax without damaging the lungs. It has a spring-loaded tension sensor with a blunt tip that retracts upon encountering resistance in the fascia and peritoneum, then rapidly ejects after passing through these layers, thus penetrating the tissue while protecting internal organs from damage. Once inside the abdominal cavity, the needle is inflated. This method of abdominal insertion has been used for nearly 40 years in many countries, particularly in gynecology. Longer pneumoperitoneum needles can be used for patients with thick abdominal walls (such as obese patients).
The commonly used puncture site is the umbilicus. The abdominal wall is manually pulled to create negative pressure within the abdominal cavity. The pneumoperitoneum needle is kept in place to maintain pressure consistent with the cavity, thus allowing the abdominal wall to be moved away from the internal organs once the peritoneum is punctured. However, some structures fixed to the abdominal wall or retroperitoneum may be damaged because they cannot be moved. Additionally, rapid entry into the abdominal cavity or failure of the blunt tip of the pneumoperitoneum needle to retract in time can also cause tissue damage. If the needle has already entered the abdominal cavity but the operator is unaware, continuing to insert it can also lead to potential organ damage.
In obese patients, the navel may be difficult to expose, and this area often harbors excessive bacteria and fungi, limiting the extent to which the abdominal wall can be pulled up. Therefore, it is recommended to perform puncture at Palmer's point (below the left costal margin, between the midclavicular line and the anterior axillary line), where the main organ is the greater omentum. Puncture is facilitated by traction on the ribs and costal cartilages above the rectus abdominis muscle, the costal sheath, and the underlying peritoneum. The superior epigastric artery at this location is usually located centrally and is less prone to injury than at other sites. However, extreme care must be taken when applying force to avoid misaligning the needle tip towards the center. At the navel, the needle should be inserted directly towards the pelvic cavity at a 45° angle (avoiding the aortic bifurcation and iliac vessels). Skin sutures can be placed at the navel to provide traction. At Palmer's point, the pneumoperitoneum needle should be inserted perpendicularly to the skin.
The pneumoperitoneum needle should be aspirated to confirm that no blood, body fluid, or feces have been drawn out. Due to gravity or the negative pressure within the abdominal cavity caused by the elevation of the abdominal wall, a drop of normal saline should be instilled at the needle tip and aspirated into the abdominal cavity. The initial carbon dioxide pneumoperitoneum pressure should be 5–8 mmHg. If the pressure is higher (>20 mmHg), it indicates that gas has been injected extraperitoneally or subcutaneously. However, there is no way to definitively confirm that the pneumoperitoneum needle is within the abdominal cavity, and even if the pneumoperitoneum needle position is correctly tested according to the above method, vascular and visceral injury can still occur. Laparoscopic puncture with a needle is considered a safer method, but this method can only detect puncture injury earlier and cannot completely prevent it.
Schwartz et al. reported that for obese patients, the puncture needle can be swirled to avoid the greater omentum. Swirling the needle increases the airflow to 1–2 L/min, creating an elliptical path with the needle tip through short, frequent, and rapid circular motions. This method was reported to have been used in 600 consecutive morbidly obese patients without death or vascular injury; one case of transverse colonic seromuscular layer injury was repaired laparoscopically without sequelae.