Laparoscopic surgery in the obese: Safe techniques
Increases in atelectasis, wound infection, and other risks after laparotomy point to laparoscopy as the safer route.
Zeroing in on pneumoperitoneum
What are the effects of pneumoperitoneum and posture in obese women undergoing gynecologic laparoscopy? A recent study13 compared 8 morbidly obese patients with 9 normal-weight controls and confirmed previous evidence that morbidly obese, supine, anesthetized patients have a 68% increase in inspiratory resistance and a 30% decrease in static pulmonary compliance, compared with controls. Pneumoperitoneum further increases this resistance and diminishes compliance.
Oxygenation is not affected
Somewhat surprisingly, this study did not detect significant changes in respiratory mechanics with head down or up positioning, and despite the exacerbation of pulmonary mechanics with pneumoperitoneum, there was no significant change in oxygenation.
The conclusion: While pneumoperitoneum impairs respiratory mechanics during anesthesia in the obese, body mass is the only variable that significantly affects oxygenation. If an obese patient can tolerate anesthesia and supine positioning—necessary for both laparoscopy and laparotomy—she is likely to tolerate changes in position and pneumoperitoneum as well.
These findings also hold true in patients undergoing bariatric surgery,14 with no significant differences in respiratory mechanics or arterial oxygenation during either laparoscopic or laparotomic surgery.
Virtually all procedures are safe
In gynecology alone, practically all of the procedures commonly performed in women of normal weight have been studied and found to be safe in obese patients. They include adnexal surgery, myomectomy, total laparoscopic hysterectomy,15-18 management of tubal ectopic pregnancy,19 endometrial cancer,20 and pelvic/periaortic lymph node dissection.20,21
Two ways of comparing outcomes
Well-designed studies tend to fall into 2 camps: those that compare laparoscopy in obese patients with laparoscopy in nonobese patients, and those that compare laparoscopy in obese patients with laparotomy in obese patients.
- A review of the gynecologic literature in the first camp15-18,22-24 reveals little to no difference between cohorts with respect to estimated blood loss, operative and postoperative complications, and hospital stay. The nongynecologic literature on laparoscopy in obese versus nonobese patients tends to corroborate these findings, with an overall trend toward increased operating times and conversion rates.25-30
- In comparing laparoscopy with laparotomy, researchers found that total operative time tends to rise with laparoscopy.20,21,31 Otherwise, laparoscopy confers benefit or no difference with respect to hospital stay, postoperative pain, estimated blood loss, lymph node counts, postoperative complications (fever, ileus, wound infection), convalescence, and total medical cost.32,33
If no allergies or contraindications exist, give 1 to 2 g of a first-or second-generation cephalosporin intravenously 20 to 30 minutes prior to anesthesia induction.
Sequential compression devices. Since both obesity and gynecologic surgery are risk factors for deep venous thrombosis, use large sequential compression devices on the lower extremities, beginning before induction of anesthesia.
Position the patient for optimal access
Only 1 recent publication explores this issue in obese laparoscopy patients. Lamvu et al5 advocate the armstucked (“military”), low lithotomy position, with liberal padding on the legs and arms and a gel pad under the lower back. They also recommend stationary shoulder blocks to help maintain positioning in the Trendelenburg (head down) position, and they use clamps, gauze, weights, and tape to maintain the panniculus in its caudad position.
Novel technique realigns umbilical axis. We, too, use padding liberally on all pressure points, but do not weight the panniculus. In fact, we prefer its cephalad migration in the Trendelenburg position. Pelosi and Pelosi6 describe a useful technique to realign the umbilical axis cephalad before placing the first trocar (FIGURE). Once the Trendelenburg position is attained (after initial trocar placement), this cephalad position eases ancillary port placement.
Tucking 1 arm facilitates surgery, anesthesia access. Tucking both arms is ideal but not always feasible. It is especially problematic when adipose tissue surrounding the biceps makes the military position impossible. Further, anesthesiologists may be unwilling to abandon access to the peripheral intravenous site, since placement and emergency replacement can be difficult.
Central venous access is always an option but is not without risk and should be avoided, if possible. A creative alternative: Tuck the nonaccessed arm at the patient’s side and place the other arm over the chest. Maintain this position by tucking a sheet over the chest. This gives the anesthesia team access to 1 arm while facilitating ideal surgeon positioning.
Do not use shoulder blocks when the patient’s arms are extended, as this increases the risk of brachial plexus injury should the patient slide.
Success hinges on port placement, pneumoperitoneum
The success or failure of most laparoscopic surgeries is determined in the initial minutes during placement of the operative ports. This is especially true in obese patients. No single variable is more important to successful laparoscopy in obese patients than the establishment of pneumoperitoneum.
