The effects of neuromuscular block on peak airway pressure and abdominal elastance during pneumoperitoneum

Effect of Neuromuscular Blockade on Intraoperative Respiratory Mechanics and Surgical Space Conditions during Robot-Assisted Radical Prostatectomy: A Prospective Randomized Controlled Trial

The aim of this study was to investigate whether deep neuromuscular blockade (NMB) may affect intraoperative respiratory mechanics, surgical condition, and recovery profiles in patients undergoing robot-assisted radical prostatectomy (RARP). Patients were randomly assigned to the moderate or deep NMB groups. Pneumoperitoneum was maintained with carbon dioxide (CO₂) insufflation at 15 mmHg during surgery. The primary outcome was peak inspiratory pressure (PIP) after CO₂ insufflation. Mean airway pressure (P_mean) and dynamic lung compliance (C_dyn) were also recorded. The surgeon rated the surgical condition and surgical difficulty on a five-point scale (1 = extremely poor; 2 = poor; 3 = acceptable; 4 = good; 5 = optimal). Recovery profiles, such as pulmonary complications, pain scores, and recovery time, were recorded. We included 58 patients in this study. No significant differences were observed regarding intraoperative respiratory mechanics including PIP, P_mean and C_dyn, between the two groups. The number of patients with optimal surgical conditions was significantly higher in the deep than in the moderate NMB group (29 vs. 20, p = 0.014). We found no differences in recovery profiles. In conclusion, deep NMB had no significant effect on the intraoperative respiratory mechanics but resulted in optimal endoscopic surgical conditions during RARP compared with moderate NMB.

Anesthetic Implications of Robotic Gynecologic Surgery

Surgery using robotic techniques is becoming more and more common. One of the specialties at the fore-front of robotic surgery has been gynecology, much like it was at the fore-front a generation ago in bringing laparoscopy into the operating room. New considerations have been noted and new techniques have been learned on both sides of the drape in order to ensure a successful outcome for the patient undergoing robotic gynecologic surgery. The purpose of this article is to bring, to light the concerns facing the anesthesiologist in regards to robotic procedures. We discuss the problems facing anesthesiologists, when a patient is experiencing both intraabdominal insufflation and steep Trendelenburg position, and also the intraoperative management of such a patient.

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.

Comparison of respiratory mechanics between sevoflurane and propofol-remifentanil anesthesia for laparoscopic colectomy

BACKGROUND

The creation of pneumoperitoneum and Trendelenburg positioning during laparoscopic surgery are associated with respiratory changes. We aimed to compare respiratory mechanics while using intravenous propofol and remifentanil vs. sevoflurane during laparoscopic colectomy.

METHODS

SIXTY PATIENTS UNDERGOING LAPAROSCOPIC COLECTOMY WERE RANDOMLY ALLOCATED TO ONE OF THE TWO GROUPS: group PR (propofol-remifentanil group; n = 30), and group S (sevoflurane group; n = 30). Peak inspiratory pressure (PIP), dynamic lung compliance (Cdyn), and respiratory resistance (Rrs) values at five different time points: 5 minutes after induction of anesthesia (supine position, T1), 3 minutes after pneumoperitoneum (lithotomy position, T2), 3 minutes after pneumoperitoneum while in the lithotomy-Trendelenburg position (T3), 30 minutes after pneumoperitoneum (T4), and 3 minutes after deflation of pneumoperitoneum (T5).

RESULTS

In both groups, there were significant increases in PIP and Rrs while Cdyn decreased at times T2, T3, and T4 compared to T1 (P < 0.001). The Rrs of group PR for T2, T3, and T4 were significantly higher than those measured in group S for the corresponding time points (P < 0.05).

CONCLUSIONS

Respiratory mechanics can be adversely affected during laparoscopic colectomy. Respiratory resistance was significantly higher during propofol-remifentanil anesthesia than sevoflurane anesthesia.

Optimizing working-space in laparoscopy: measuring the effect of mechanical bowel preparation in a porcine model

BACKGROUND

Adequate working space is a prerequisite for safe and efficient minimal access surgery. No objective data exist in literature about the effect of mechanical bowel preparation (MBP) on working space in laparoscopic surgery. We objectively measured this effect with computed tomography in a porcine laparoscopy model.

METHODS

Using standardized anesthesia, twelve 20-kg pigs without MBP and eight 20-kg pigs with MBP were studied with computed tomography at intra-abdominal pressure (IAP) levels of 0, 5, 10, and 15 mmHg. Volumes and dimensions of the pneumoperitoneum were measured on reconstructed CT images and compared between the pigs with and those without MBP.

RESULTS

A reproducible and statistically significant increase of approximately 500 ml in pneumoperitoneum volume was found in the MBP group at all levels of IAP. This represents a 43 % relative increase at a pneumoperitoneum pressure of 5 mmHg, 21 % at IAP 10 mmHg, and 18 % at IAP 15 mmHg. Peak inspiratory pressure was lower at IAP 0 and 5 mmHg in the MBP group. Anteroposterior diameter in the group with MBP was lower at 0 mmHg, but abdominal dimensions were similar in both groups at all other IAPs. This shows that the gain in working space is due to a diminished volume of the intra-abdominal content and not to compression or displacement of the bowel.

CONCLUSIONS

MBP increases working space by reducing bowel content. Especially at low intra-abdominal working pressures, the increase in working space associated with MBP could represent an important benefit in challenging laparoscopic surgery.

Impact of the patient's body position on the intraabdominal workspace during laparoscopic surgery

Background

The effects of the patient’s body position on the intraabdominal workspace in laparoscopic surgery were analyzed.

Methods

The inflated volume of carbon dioxide was measured after insufflation to a preset pressure of 15 mmHg for 20 patients with a body mass index (BMI) greater than 35 kg/m². The patients were anesthetized with full muscle relaxation. The five positions were (1) table horizontal with the legs flat (supine position), (2) table in 20° reverse Trendelenburg with the legs flat, (3) table in 20° reverse Trendelenburg with the legs flexed 45° upward at the hips (beach chair position), (4) table horizontal with the legs flexed 45° upward at the hips, and (5) table in 20° Trendelenburg with the legs flat. The positions were performed in a random order, and the first position was repeated after the last measurement. Repeated measure analysis of variance was used to compare inflated volumes among the five positions.

Results

A significant difference in inflated volume was found between the five body positions (P = 0.042). Compared with the mean inflated volume for the supine position (3.22 ± 0.78 l), the mean inflated volume increased by 900 ml for the Trendelenburg position or when the legs were flexed at the hips, and decreased by 230 ml for the reverse Trendelenburg position.

Conclusions

The Trendelenburg position for lower abdominal surgery and reverse Trendelenburg with flexing of the legs at the hips for upper abdominal surgery effectively improved the workspace in obese patients, even with full muscle relaxation.