A Novel Device for Peritoneal Access in Laparoscopic Surgery

Introduction

Laparoscopy is one of the most common surgical procedures performed in the United States today. It is the modality of choice for many physicians for removal of ectopic pregnancy, bilateral tubal sterilization, treatment of endometriosis, lysis of adhesions, cholecystectomy, appendectomy, splenectomy, prostatectomy, etc.  It is becoming increasingly popular for more complex procedures, including laparoscopic hysterectomy and myomectomy.

It has been shown that one in three complications of laparoscopic surgery occur during the set-up phase of laparoscopy, which includes the creation of pneumoperitoneum and initial trocar entry.¹  More specifically, over 50% of laparoscopic injuries to the gastrointestinal tract and major vessels occur during the initial entry phase.^2-7 

Therefore, it is of utmost importance to choose a method of entry which minimizes risk of injury to the patient.  No clear advantages have been demonstrated from the available modalities for abdominal entry.  Closed entry techniques, which include use of the Veress needle or direct trocar insertion to establish pneumoperitoneum, have not been shown to have advantages over one another, nor over open entry with the Hasson technique.⁸ 

Nevertheless, closed entry with the Veress needle is the most popular method of entry for gynecologic laparoscopists.⁸  About 96.3 % of gynecologic laparoscopies in the United States are initiated by insertion of Veress needle for creation of pneumoperitoneum.⁹ Although this method of entry is generally considered to be safe, Veress needle injuries to numerous abdominal structures have been reported.¹⁰

The rate of major injury from peritoneal entry with the Veress needle is reported at 0.9/1000 cases.7 Rates of entry-related bowel and vascular injury were 0.4/1000 and 0.2-0.4/1000 cases, respectively, with the Veress needle technique.^4-7  Although major vascular injury is rare, it carries significant risk of major morbidity or death.¹²

The risk of injury increases dramatically with repeated attempts at entry. ^{14, 15}  The reported first pass failure rate of the Veress needle is 14.5 %.^{13, 14} The reported risk of needle- related injury after the second attempt increases to between 16.3% and 37.5% with even higher rates reported with subsequent attemtps.^{13, 14} These types of complications are dangerous for the patient, frustrating to the surgeon and costly to the hospital. Certainly, the introduction of a device which aids in safe and successful Veress needle entry into the abdomen is a welcome addition to the surgeon’s armamentarium.

Recently, a new method for Veress needle insertion has been introduced which has the potential to increase first-pass Veress needle insertion rates and decrease rates of retroperitoneal vascular injury.   This new pneumoperitoneum creation assist device (PCAD) is named LapCap (Aragon Surgical, Inc. Palo Alto, CA). It is designed to assist in blind Veress needle insertion.  It also obviates the need for a surgeon to employ the use of an assistant or to apply penetrating clamps to the patient’s skin to aid in elevation of the abdominal wall.  Furthermore, it has the potential to reduce operator-depenency and increase automaticity in standardizing a method of safe entry into the peritoneal cavity.

The safety and efficacy of LapCap was first studied in a pilot group of 48 women.¹⁷ In all patients, pneumoperitoneum was achieved with first passage of the Veress needle and no injuries were reported.  We have been using LapCap since early 2007 and present to you our experience with the device and hope to share our recommendations with your readers.

Methods

After the patient is anesthetized, she is placed in a supine or dorsal lithotomy position and draped.  It is of utmost importance that the patient’s abdominal muscles are completely paralyzed and that she remains parallel to the floor (i.e. flat, without Trendelenburg positioning). An oro-gastric tube is inserted and bladder is drained to avoid distention of these organs. After palpation for anatomic landmarks including the sacral promontory and the pulsations of the abdominal aorta, the LapCap can be used to accomplish Veress needle insertion.

The device itself consists of a transparent dome with a central needle pass-through port (Figure I).  The dome is connected to a regular wall vacuum line via a lateral port.  We have used it in three different ways.

1. Suction first

The Veress needle is selected based on the patient’s body habits.  Whereas a 12cm sharp, disposable Veress needle can be used for very thin patients, a 15cm needle is ideal for patients of average or heavier body mass index. The LapCap is placed over the peri-umbilical area with the needle pass-through port roughly centered over the umbilicus itself.  

Sterile suction tubing is connected to the LapCap vacuum line port and maximum standard wall suction is applied. This suction elevates full-thickness abdominal wall into the dome, creating a cone-shaped vacuum space of peritoneal cavity within the LapCap dome. No incision is necessary as suction will draw blood from the skin incision. The suction is then released and the abdominal wall is allowed to fall back into place.  This process is repeated approximately three times in order to ensure adequate relaxation of the abdominal wall and to help to displace the omentum from the anterior abdominal wall.  Suction is applied one final time and, with the abdominal wall elevated within the device, the Veress needle is advanced through the LapCap needle pass-through (Figure II). In the very thin patients, we insert only a small portion (5 cm) of a 12 cm needle. However, in average or obese patients, we often insert the full length of a 15 cm needle. Usually, a triple-click indicates passage through the skin, fascia and peritoneum, but we cannot rely on these clicks as they may not be appreciable. 

Intra-abdominal placement of the needle cannot be confirmed by the “saline drop test”¹³ as it is not feasible for the drop of saline to fall freely into the abdominal cavity in the setting of the vacuum. However, the instillation and aspiration of 3-5 cc of saline through the Veress needle is recommended so as to dislodge any small fragments of skin or tissue which might obstruct gas flow through the needle. It also negates theoretical concern of blood and bowel aspiration. Insufflation may then commence. 

We have discovered that the pressure reading with the LapCap in place is elevated to almost double the actual intra-abdominal pressure because of the smaller volume of the abdominal cavity associated with sequestration of a portion of the abdominal wall with in the Lap Cap. While using a Veress needle without the support of the LapCap, an opening pressure below 10 mmHg was expected from intra-peritoneal placement.¹³ However, with the traction of LapCap, pressures up to 20 mmHg are associated with appropriate placement.

Insufflation can then continue with the flow of CO2 increased to 40 L/min.  Pneumoperitoneum should be established at an intra-abdominal pressure of 20 mmHg. When this pressure is reached, the stopcock connecting to the wall suction is turned off. We do not tighten the screw lock of the cap over the needle. The LapCap will spontaneously release itself from the abdominal wall and the intraperitoneal pressure will decrease significantly, usually to 10-12mm Hg.  The Veress needle then remains in place and insufflation is continued until the pressure reaches 20 mmHg again. 

When the intended pressure is achieved, the LapCap is removed (Figure III).  Some physicians may choose to proceed with mapping¹⁵ of the abdominal cavity in patients with prior surgery.  We recommend reinsertion of the Veress needle at a site separate from where the primary trocar is to be placed (often a few centimeters lateral to the umbilicus to either side or in the the left upper quadrant) prior to mapping; otherwise gas leakage may slightly reduce intra-abdominal pressure. A high level of intra-abdominal pressure at the time of trocar entry is recommended so as to increase the distance between the abdominal skin and vital underlying organs and vasculature.¹⁶ 

Following these steps, the abdomen is ready for insertion of the trocar without any need to elevate the abdominal wall. After safe entry, the intra-abdominal pressure should be decreased to a maximum of 15 mmHg.

2. Needle First

The appropriate Veress needle is again selected based on the patient’s body habits. The needle is advanced through the LapCap needle pass-through port up to a point 1-2cm beyond the lower edge of the LapCap. The needle is held in place by turning the needle pass-through port knob in a clockwise direction until it is locked. The LapCap is then placed on the patient’s abdominal wall with the needle tip touching the patient’s skin close to or just under the umbilicus. No incision is necessary. Of note, in very thin patients very little of the Veress needle (<5cm) should protrude from beyond the rim of the LapCap dome.

Sterile suction tubing is then connected to the LapCap vacuum line port and standard suction is applied. The suction will elevate the full thickness of the abdominal wall into the device dome, thereby advancing the needle through the abdominal wall and into the cone shaped vacuum space created within the LapCap dome.  Confirmation of intra-abdominal placement and insufflation are then carried out in a manner identical to the method described above.

3. Alternative Insertion site

For some patients with a history of midline laparotomy or a high likelihood of dense periumbilical adhesions, abdominal entry at a site distant from the umbilicus may be desired.  We have used this instrument in the left upper quadrant and subxiphoid area successfully under these conditions.  Again, mapping is recommended prior to primary trocar placement.

Our Experience
         

Using the LapCap, we achieved successful abdominal entry in all patients in whom the technique was attempted. On average, we required only one passage of the needle and the vast majority of entries were successful at first attempt. Although an opening pressure of up to 15 mmHg always reflected proper placement in our patients, some patients had a higher opening pressure (up to 20mmHg) and were nevertheless proven to have undergone successful placement of the Veress needle.

The cause of higher pressures in our cohort have been investigated and linked to causes including an inadvertently closed Veress needle, kinked gas tubing, contact with a large uterus, extraperitoneal placement, or proximity to either the omentum or an intraabdominal adhesion. Those situations help explain few cases requiring more than one application of the needle.

It should also be noted that higher initial abdominal (opening) pressures are to be expected with using the LapCap as opposed to those encountered when practicing conventional entry with the Veress needle. These initial pressure readings are not necessarily reflective of the actual intra-abdominal pressure, but of the pressure within the small dome-shaped cavity created by the LapCap, as evidenced by the fact that the intra-abdominal pressure reading drops dramatically (almost half) when the LapCap suction is turned off upon initially reaching 20 mmHg.

At this time, given our findings of successful entry with patients with opening pressure readings up to 20 mmHg and in all patients up to 15 mmHg, we feel comfortable considering pursuing insufflations with an opening pressure less than or equal to 17 mmHg, and possibly higher depending upon our clinical judgment. 

It should also be noted that the vacuum-first method is now our preferred method of use. We find that the technique offers a greater sense of control during entry with the Veress needle. While we find this method particularly helpful when teaching practitioners who are already familiar with other techniques of elevating the abdominal wall prior to attempted entry with the Veress needle, we find that the increased sense of precision increases even seasoned LapCap users comfort level as compared with the needle-first method.  

The ‘bottom line,’ however is safety.  In over 135 patients, we have had no retroperitoneal or vascular injuries. Neither have we had any patients experience skin trauma (ecchymosis or punctures) apart from the Veress entry site.  However, the limitations of our experience include the fact this small series did not include enough patients to show a significant difference in the small rate of vascular injuries associated with conventional use of the Veress needle (estimated to be around 0.3/1000 cases.4-7)

Inexperienced Users

The ease of use of the LapCap technique was particularly advantageous for the purposes of teaching abdominal entry to residents, fellows and attending physicians who do not have extensive experience in creating pneumoperitoneum using the Veress needle. 

In our experience of introducing the LapCap to other surgeons, initial adaptations to this new technology have been very positive even for the seasoned laparoscopist.

However, because entry with the LapCap differs from conventional practices for Veress needle insertion, there is a definite learning curve for new users. 

The sight of the abdominal wall being vacuumed into the dome is unfamiliar to new users and some expressed concerns for skin bruising, although no evidence of superficial barotrauma was noted in our experience. Our experience also revealed that new users are likely not to insert the Veress needle deeply enough in the LapCap to enter the peritoneal cavity, as these lengths seemed excessive to practitioners accustomed to inserting the needle directly into the elevated abdominal wall.  New users also tended to remove the device when the opening pressure was above 10 mmHg, even though our data show that it is likely they had achieved proper placement.  New users were also unaccustomed to insertion of the Veress needle without a prior skin incision, necessitating the third click as an auscultatory adaptation for practitioners who usually seek only two.  

New users generally responded positively to their experience with the LapCap.  Skilled laparoscopists, especially in teaching institutions, had an increased level of comfort associated with the sense of controlled entry which the LapCap creates.  Less-seasoned laparoscopists appreciated the fact that the device makes the creation of pneumoperitoneum practically “automatic”.

It is likely that new users will have to change their expectations, modeled on techniques developed prior to the advent of the LapCap, and adapt their practice to meet the parameters we have found to be associated with successful use of the device. We expect surgeons familiar with the device will reach a rate close to 100% for successful entry at first attempt even on difficult cases as we did.  In order to maximize success, we believe that surgeons should learn this technique from other practitioners who are experienced using the LapCap.

Conclusions

The LapCap is a simple device which has allowed our team to create pneumoperitoneum with ease and predictability even on obese patients or those with multiple prior surgeries.  It is, in our opinion, a novel technology which has the potential to decrease and may eliminate the risk of retroperitoneal injury associated with the use of Veress needle.  As it has the potential to avoid rare but truly disastrous complications, it deserves to be further evaluated and tested.

We believe that although experienced endoscopists may feel they don’t need this instrument (as we did), they should consider learning how to use it.  They may find it especially useful in teaching safe abdominal entry to the novice in laparoscopic surgery and enjoy the comfort of knowing they have done their best to maximize the patient’s safety.

References:

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