[Gynecologic laparoscopy with or without curare]

Deep versus Moderate Neuromuscular Blockade in Gynecologic Laparoscopic Operations: Randomized Controlled Trial

Background: To investigate whether deep neuromuscular blockade (NMB) improves surgical conditions and postoperative pain compared to moderate block, in patients undergoing gynecologic laparoscopic surgery. Methods: A single blind, randomized, controlled trial was undertaken with laparoscopic gynecologic surgical patients, who were randomly assigned to one of the following two groups: patients in the first group received deep NMB (PTC 0-1) and in the other, moderate NMB (TOF 0-1). Primary outcomes included assessing the surgical conditions using a four-grade scale, ranging from 0 (extremely poor) to 3 (optimal), and patients’ postoperative pain was evaluated with a five-grade Likert scale and the analgesic consumption. Results: 144 patients were analyzed as follows: 73 patients received deep NMB and 71 moderate NMB. Mean surgical field scores were comparable between the two groups (2.44 for moderate vs. 2.68 for deep NMB). Regarding postoperative pain scores, the patients in the deep NMB experienced significantly less pain than in the group of moderate NMB (0.79 vs. 1.58, p < 0.001). Moreover, when the consumption of analgesic drugs was compared, the moderate NMB group needed more extra opioid analgesia than the deep NMB group (18.3% vs. 4.1%, p = 0.007). From the secondary endpoints, an interesting finding of the study was that patients on deep NMB had significantly fewer incidents of subcutaneous emphysema. Conclusions: Our data show that, during the performance of gynecologic laparoscopic surgery, deep NMB offers no advantage of operating filed conditions compared with moderate NMB. Patients may benefit from the deep block as it may reduce postoperative pain.

Laparoscopic surgery and muscle relaxants: is deep block helpful?

It has been hypothesized that providing deep neuromuscular block (a posttetanic count of 1 or more, but a train-of-four [TOF] count of zero) when compared with moderate block (TOF counts of 1-3) for laparoscopic surgery would allow for the use of lower inflation pressures while optimizing surgical space and enhancing patient safety. We conducted a literature search on 6 different medical databases using 3 search strategies in each database in an attempt to find data substantiating this proposition. In addition, we studied the reference lists of the articles retrieved in the search and of other relevant articles known to the authors. There is some evidence that maintaining low inflation pressures during intra-abdominal laparoscopic surgery may reduce postoperative pain. Unfortunately most of the studies that come to these conclusions give few if any details as to the anesthetic protocol or the management of neuromuscular block. Performing laparoscopic surgery under low versus standard pressure pneumoperitoneum is associated with no difference in outcome with respect to surgical morbidity, conversion to open cholecystectomy, hemodynamic effects, length of hospital stay, or patient satisfaction. There is a limit to what deep neuromuscular block can achieve. Attempts to perform laparoscopic cholecystectomy at an inflation pressure of 8 mm Hg are associated with a 40% failure rate even at posttetanic counts of 1 or less. Well-designed studies that ask the question "is deep block superior to moderate block vis-à-vis surgical operating conditions" are essentially nonexistent. Without exception, all the peer-reviewed studies we uncovered which state that they investigated this issue have such serious flaws in their protocols that the authors' conclusions are suspect. However, there is evidence that abdominal compliance was not increased by a significant amount when deep block was established when compared with moderate neuromuscular block. Maintenance of deep block for the duration of the pneumoperitoneum presents a problem for clinicians who do not have access to sugammadex. Reversal of block with neostigmine at a time when no response to TOF stimulation can be elicited is slow and incomplete and increases the potential for postoperative residual neuromuscular block. The obligatory addition of sugammadex to any anesthetic protocol based on the continuous maintenance of deep block is not without associated caveats. First, monitoring of neuromuscular function is still essential and second, antagonism of deep block necessitates doses of sugammadex of ≥4.0 mg/kg. Thus, maintenance of deep block has substantial economic repercussions. There are little objective data to support the proposition that deep neuromuscular block (when compared with less intense block; TOF counts of 1-3) contributes to better patient outcome or improves surgical operating conditions.

Optimizing working space in laparoscopy: CT measurement of the influence of small body size in a porcine model

INTRODUCTION

In our continuing research into the determinants of laparoscopic working space, the influence of small body size was investigated.

METHODS

In eight 6-kg pigs, the effects of intraabdominal CO2 pneumoperitoneum pressure (IAP), prestretching of the abdominal wall, and neuromuscular blockade (NMB) on laparoscopic working space volume and distances were studied. Computed tomography was used to measure working space during two stepwise abdominal insufflation-runs up to an IAP of 15mm Hg. Results were compared with data from earlier experiments in 20-kg pigs.

RESULTS

Cardiorespiratory parameters were stable up to an IAP of 8-10mm Hg. In 6-kg pigs working-space dimensions were five times smaller than in 20-kg pigs. Working-space volume, anteroposterior (AP) diameter and symphysis-diaphragm distance increased linearly up to an IAP of 8mm Hg. Above 8mm Hg, compliance decreased. Eighty percent of the total volume (618ml) and of AP diameter (3cm) at 15mm Hg had been achieved at an IAP of 10mm Hg. Prestretching by a first insufflation resulted in a statistically significant increase in working space volume and in AP diameter during the second insufflation. This effect was significantly larger than in 20-kg pigs. Neuromuscular blockade did not have a significant effect on working-space.

CONCLUSIONS

Working space in growing individuals is very limited. Eighty percent of the working space created by an IAP of 15mm Hg was already achieved at 10mm Hg, while cardiorespiratory side effects at an IAP of 8-10mm Hg seem acceptable. Prestretching of the abdominal wall significantly increased working space, even more so than in 20-kg pigs. As in 20-kg pigs, NMB had no significant effect on laparoscopic working space. Prestretching of the abdominal wall is a promising cheap, safe and easy strategy to increase laparoscopic working space, lessening the need for prolonged high-pressure pneumoperitoneum.

Neuromuscular blockade for optimising surgical conditions during abdominal and gynaecological surgery: a systematic review

BACKGROUND

The level of neuromuscular blockade (NMB) that provides optimal surgical conditions during abdominal surgery has not been well established. The aim of this systematic review was to evaluate current evidence on the use of neuromuscular blocking agents in order to optimise surgical conditions during laparoscopic procedures and open abdominal surgery.

METHODS

A wide search was performed in PubMed, Cochrane library and Embase with systematic approach including PRISMA recommendations. Individual risk of bias was assessed and systematic data extraction were performed.

RESULTS

Fifteen studies with data from 998 patients were included. There is good evidence that the use of deep NMB compared with moderate NMB is associated with optimised surgical conditions during laparoscopic cholecystectomy, hysterectomy and nephrectomy/prostatectomy. In laparoscopic cholecystectomy during low pressure pneumoperitoneum, deep NMB marginally improves the surgical conditions. However, to ensure acceptable surgical conditions, it may be necessary to increase the intra-abdominal pressure in up to half of the patients regardless of level of NMB. There is good evidence that moderate NMB improves surgical conditions in some cases during open radical retropubic prostatectomy. However, good and excellent surgical conditions may be achievable even without NMB. There is good evidence to recommend deep NMB in laparoscopic cholecystectomy, nephrectomy and prostatectomy to improve surgical conditions. There is insufficient evidence to recommend an ideal level of NMB creating optimal surgical condition during laparotomy.

CONCLUSION

Use of deep NMB in certain laparoscopic procedures may improve surgical conditions. In open abdominal surgery, use of NMB may optimise surgical conditions under certain circumstances.

Optimizing working space in laparoscopy: CT-measurement of the effect of neuromuscular blockade and its reversal in a porcine model

OBJECTIVE

The objective of this paper was to determine the effect of neuromuscular blockade (NMB) on working space in a porcine laparoscopy model.

BACKGROUND

Conflicting results on the effect of NMB on laparoscopic working space are found in literature. Almost all studies are limited by absence of objective assessment of working space or use surrogate outcomes.

METHODS

In a standardized porcine laparoscopy model, laparoscopic working-space dimensions with and without NMB were investigated in 16 animals using computed tomography at intra-abdominal pressures of 0, 5, 10, and 15 mmHg during multiple runs of abdominal insufflation.

RESULTS

No statistically significant effect of NMB on abdominal dimensions and laparoscopic working-space volume was found during CO2 pneumoperitoneum. In contrast, the effect of pre-stretching of the abdominal wall by a previous abdominal insufflation was found to be significant.

CONCLUSIONS

This experimental study confirms the results from several clinical studies that NMB does not influence laparoscopic working space. Studies dealing with working space during laparoscopy should take note of pre-stretching bias.

Is muscle relaxant necessary in patients undergoing laparoscopic gynecological surgery with a ProSeal LMA™?

STUDY OBJECTIVE

To test the hypothesis that muscle relaxant is not necessary in patients who are undergoing laparoscopic gynecological surgery with a ProSeal Laryngeal Mask Airway (ProSeal LMA™).

DESIGN

Prospective, randomized study.

SETTING

Operating room of Sichuan Provincial Hospital for Women and Children.

PATIENTS

120 adult, ASA physical status 1 and 2 women, aged 18 to 55 years.

INTERVENTIONS AND MEASUREMENTS

Patients were randomly assigned to two groups (n=60) to receive a muscle relaxant (Group MR) or not (Group NMR). General anesthesia was used in patients of both groups for airway management with the ProSeal LMA. Peak airway inflation pressures, airway sealing pressure, minimum flow rate, and recovery time were assessed. Surgical conditions were assessed by the operating gynecologist. The frequency of sore throats was recorded.

MAIN RESULTS

ProSeal LMA insertion was 100% successful. Patients' lungs were ventilated with a maximum sealing pressure of 32 ± 5.1 cm H(2)O (Group MR) or 31 ± 4.9 cm H(2)O (Group NMR) (P = 0.341). The seal quality in both groups permitted the use of low flows: 485 ± 291 mL/min in Group MR and 539 ± 344 mL/min in Group NMR (P = 0.2). Surgical conditions were comparable between the two groups. There was no difference in the frequency of sore throats (20% vs 21.7%; P = 0.28). In Group NMR, there was a statistically significant reduction in recovery time versus Group MR (4.5 ± 2.6 min vs 10.3 ± 4.2 min; P < 0.01).

CONCLUSION

Muscle relaxant is not necessary in general anesthesia with a ProSeal LMA.

Beneficial effects of high positive end-expiratory pressure in lung respiratory mechanics during laparoscopic surgery

BACKGROUND

The effect of neuromuscular blockade (NMB) and positive end-expiratory pressure (PEEP) on the elastic properties of the respiratory system during pneumoperitoneum (PnP) remains a controversial subject. The main objective of the present study was to evaluate the effects of NMB and PEEP on respiratory mechanics.

METHODS

We performed a dynamic analysis of respiratory mechanics in patients subjected to PnP. Twenty-one patients underwent cholecystectomy videolaparoscopy and total intravenous anesthesia. The respiratory system resistance (R(RS)), pulmonary elastance (E(P)), chest wall elastance (E(CW)), and respiratory system elastance (E(RS)) were computed via the least squares fit technique using an equation describing the motion of the respiratory system, which uses primary signs such as airway pressure, tidal volume, air flow, and esophageal pressures. Measurements were taken after tracheal intubation, PnP, NMB, establishment of PEEP (10 cmH2O), and PEEP withdrawal [zero end-expiratory pressure (ZEEP)].

RESULTS

PnP significantly increased E(RS) by 27%; both E(P) and E(CW) increased 21.3 and 64.1%, respectively (P < 0.001). NMB did not alter the respiratory mechanic properties. Setting PEEP reduced E(RS) by 8.6% (P < 0.05), with a reduction of 10.9% in E(P) (P < 0.01) and a significant decline of 15.7% in R(RS) (P < 0.05). These transitory changes in elastance disappeared after ZEEP.

CONCLUSIONS

We concluded that the 10 cmH2O of PEEP attenuates the effects of PnP in respiratory mechanics, lowering R(RS), E(P), and E(RS). These effects may be useful in the ventilatory approach for patients experiencing a non-physiological increase in IAP owing to PnP in laparoscopic procedures.