An Evaluation of Gas Humidifying Devices as a Means of Intraperitoneal Local Anesthetic Administration for Laparoscopic Surgery

Intraperitoneal nebulization of ropivacaine for control of pain after laparoscopic cholecystectomy -A randomized control trial

Background and Aims:

Use of high dose opioids following laparoscopic surgery delays discharge from the hospital. Unlike intraperitoneal instillation, nebulization has been reported to provide a homogeneous spread of local anesthetics and provide better analgesia. In our study, we aimed to assess the efficacy of intraperitoneal nebulization of local anesthetic in alleviating postoperative pain in patients undergoing laparoscopic cholecystectomy.

Material and Methods:

This randomized control double-blinded study was conducted after obtaining approval from the hospital ethics committee and informed consent from patients undergoing laparoscopic cholecystectomy under general anesthesia. Patients recruited were divided into two equal groups of 20 each. Group B received intraperitoneal nebulization with 4 ml of 0.75% ropivacaine and Group C received intraperitoneal nebulization with 4ml of saline before surgical dissection. Postoperative pain score using a numeric rating scale was monitored until 24 h, the need for rescue analgesics and associated complications were noted. Chi-square test, Student's test, and Mann–Whitney U test were used for statistical analysis.

Results:

The pain score was significantly less in Group B during rest and deep breathing up to 24 h with a P value <0.05. The pain score on movement was also less in Group B and this difference was statistically significant at 6 and 24 h (P = 0.004 and 0.005, respectively). Tramadol consumption was less in Group B and was statistically significant at 24 h with P value of 0.044. No adverse events were noted.

Conclusion:

Intraperitoneal nebulization of ropivacaine is effective and safe in providing postoperative analgesia in patients undergoing laparoscopic cholecystectomy.

Population Pharmacokinetics of Intraperitoneal Bupivacaine Using Manual Bolus Atomization Versus Micropump Nebulization and Morphine Requirements in Young Children

BACKGROUND

Intraperitoneal (IP) administration of local anesthetics is used in adults and children for postoperative analgesia after laparoscopic surgery. Population pharmacokinetics (PK) of IP bupivacaine has not been determined in children. Objectives of this study were (1) to develop a population PK model to compare IP bupivacaine administered via manual bolus atomization and micropump nebulization and (2) to assess postoperative morphine requirements after intraoperative administration. We hypothesized similar PK profiles and morphine requirements for both delivery methods.

METHODS

This was a prospective, sequential, observational study. After institutional review board (IRB) approval and written informed parental consent, 67 children 6 months to 6 years of age undergoing robot-assisted laparoscopic urological surgery received IP bupivacaine at the beginning of surgery. Children received a total dose of 1.25 mg/kg bupivacaine, either diluted in 30-mL normal saline via manual bolus atomization over 30 seconds or undiluted bupivacaine 0.5% via micropump nebulization into carbon dioxide (CO2) insufflation tubing over 10-17.4 minutes. Venous blood samples were obtained at 4 time points between 1 and 120 minutes intraoperatively. Samples were analyzed by liquid chromatography with mass spectrometry. PK parameters were calculated using noncompartmental and compartmental analyses. Nonlinear regression modeling was used to estimate PK parameters (primary outcomes) and Mann-Whitney U test for morphine requirements (secondary outcomes).

RESULTS

Patient characteristics between the 2 delivery methods were comparable. No clinical signs of neurotoxicity or cardiotoxicity were observed. The range of peak plasma concentrations was 0.39-2.44 µg/mL for the manual bolus atomization versus 0.25-1.07 μg/mL for the micropump nebulization. IP bupivacaine PK was described by a 1-compartment model for both delivery methods. Bupivacaine administration by micropump nebulization resulted in a significantly lower Highest Plasma Drug Concentration (Cmax) and shorter time to reach Cmax (Tmax) (P < .001) compared to manual bolus atomization. Lower plasma concentrations with less interpatient variability were observed and predicted by the PK model for the micropump nebulization (P < .001). Adjusting for age, weight, and sex as covariates, Cmax and area under the curve (AUC) were significantly lower with micropump nebulization (P < .001). Regardless of the delivery method, morphine requirements were low at all time points. There were no differences in cumulative postoperative intravenous/oral morphine requirements between manual bolus atomization and micropump nebulization (0.14 vs 0.17 mg/kg; P = .85) measured up to 24 hours postoperatively.

CONCLUSIONS

IP bupivacaine administration by micropump nebulization demonstrated lower plasma concentrations, less interpatient variability, low risk of toxicity, and similar clinical efficacy compared to manual bolus atomization. This is the first population PK study of IP bupivacaine in children, motivating future randomized controlled trials to determine efficacy.

Intraperitoneal nebulization versus intraperitoneal instillation of ropivacaine for postoperative pain management following laparoscopic donor nephrectomy

BACKGROUND

Laparoscopic donor nephrectomy is considered less painful than open nephrectomy but is still associated with significant postoperative pain. Studies reported that intraperitoneal instillation of local anesthetics provides uncertain pain relief after laparoscopic surgery. This randomized, double-blind study evaluated the effect of intraperitoneal nebulization of ropivacaine on postoperative pain relief after laparoscopic donor nephrectomy.

METHODS

Sixty patients undergoing elective laparoscopic donor nephrectomy were randomly assigned to receive either an instillation of 20 ml 0.5% ropivacaine after the induction of pneumoperitoneum or nebulization of 5 ml 1% ropivacaine before and after surgery. The primary outcome was the degree of pain relief (static and dynamic) after surgery. The secondary outcomes were postoperative fentanyl consumption, incidence of shoulder pain, unassisted walking and postoperative nausea and vomiting (PONV). Data were collected in the postanesthesia care unit (PACU) and at 6, 24, and 48 h after surgery.

RESULTS

Compared to patients in the instillation group, those in the nebulization group showed significant reductions in postoperative pain and fentanyl consumption, and none complained of significant shoulder pain (visual analog scale score ≥ 30 mm). Within 20 h of surgery, 13.3% of patients in the instillation group and 93.3% in the nebulization group started unassisted walking (absolute risk reduction, 38%; P = 0.001). In the nebulization group, PONV was significantly reduced in the PACU and at 6 h.

CONCLUSIONS

Intraperitoneal nebulization of ropivacaine reduced postoperative pain, fentanyl consumption, referred shoulder pain, and PONV while enabling earlier mobility without any difference in the length of hospital stay.

Nebulized analgesia during laparoscopic appendectomy (NALA): A randomized triple-blind placebo controlled trial

PURPOSE

Postoperative pain remains a considerable concern for patients and families. We assessed whether nebulized ropivacaine reduces morphine consumption and pain after laparoscopic appendectomy for uncomplicated appendicitis in children.

METHODS

Patients 7-17 years old with uncomplicated appendicitis were randomized to ropivacaine (intervention arm) or saline nebulization (placebo arm) at the onset of laparoscopy. Nonconsenting individuals were treated with standard care and invited to provide clinical data (baseline arm). The primary outcome was in-patient morphine utilization. Secondary outcomes included pain scores at multiple time-points, markers of recovery, operative times, and surgeon satisfaction. The trial was registered (NCT02624089).

RESULTS

Study enrollment was 116 patients over a 1-year period: Intervention (n = 43), Placebo (n = 39), Baseline (n = 34). No differences in baseline characteristics were noted between groups. No difference was noted in overall in-patient morphine consumption between randomized groups (0.31 vs. 0.35 mg/kg, p = 0.42) or between ropivacaine and baseline (0.31 vs. 0.277 mg/kg, p = 0.62). Although operative times were comparable between groups, 63% of surgeon respondents felt that nebulization obscured visualization.

CONCLUSION

Nebulized ropivacaine did not reduce postoperative morphine consumption or pain scores after laparoscopic appendectomy for simple appendicitis in children. Given that it decreases visualization and likely increases costs, nebulized administration of intraperitoneal analgesia does not appear warranted in this context.

TYPE OF STUDY

Treatment study.

LEVEL OF EVIDENCE

Level I.

Peritoneal Nebulization of Ropivacaine during Laparoscopic Cholecystectomy: Dose Finding and Pharmacokinetic Study

Background. Intraperitoneal nebulization of ropivacaine reduces postoperative pain and morphine consumption after laparoscopic surgery. The aim of this multicenter double-blind randomized controlled trial was to assess the efficacy of different doses and dose-related absorption of ropivacaine when nebulized in the peritoneal cavity during laparoscopic cholecystectomy. Methods. Patients were randomized to receive 50, 100, or 150 mg of ropivacaine 1% by peritoneal nebulization through a nebulizer. Morphine consumption, pain intensity in the abdomen, wound and shoulder, time to unassisted ambulation, discharge time, and adverse effects were collected during the first 48 hours after surgery. The pharmacokinetics of ropivacaine was evaluated using high performance liquid chromatography. Results. Nebulization of 50 mg of ropivacaine had the same effect of 100 or 150 mg in terms of postoperative morphine consumption, shoulder pain, postoperative nausea and vomiting, activity resumption, and hospital discharge timing (>0.05). Plasma concentrations did not reach toxic levels in any patient, and no significant differences were observed between groups (P > 0.05). Conclusions. There is no enhancement in analgesic efficacy with higher doses of nebulized ropivacaine during laparoscopic cholecystectomy. When administered with a microvibration-based aerosol humidification system, the pharmacokinetics of ropivacaine is constant and maintains an adequate safety profile for each dosage tested.

Infrared image monitoring of local anesthetic poisoning in rats

BACKGROUND AND OBJECTIVES

To evaluate the thermographic predictive value of local anesthetic poisoning in rats that indicates the early recognition of thermal signs of intoxication and enable the immediate start of advanced life support.

METHODS

Wistar rats underwent intraperitoneal injection of saline and ropivacaine; they were allocated into pairs, and experiments performed at baseline and experimental times. For thermography, central and peripheral compartment were analyzed, checking the maximum and average differences of temperatures between groups. Thermographic and clinical observations were performed for each experiment, and the times in which the signs of intoxication occurred were recorded. In the thermal analysis, the thermograms corresponding to the times of interest were sought and relevant data sheets extracted for statistical analysis.

RESULTS

Basal and experimental: the display of the thermal images at times was possible. It was possible to calculate the heat transfer rate in all cases. At baseline it was possible to see the physiology of microcirculation, characterized by thermal distribution in the craniocaudal direction. It was possible to visualize the pathophysiological changes or thermal dysautonomias caused by intoxication before clinical signs occur, characterized by areas of hyper-radiation, translating autonomic nervous system pathophysiological disorders. In animals poisoned by ropivacaine, there was no statistically significant difference in heat transfer rate at the experimental time.

CONCLUSIONS

The maximum temperature, medium temperature, and heat transfer rate were different from the statistical point of view between groups at the experimental time, thus confirming the systemic thermographic predictive value.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Aerosolized intraperitoneal local anesthetic for laparoscopic surgery: a randomized, double-blinded, placebo-controlled trial

BACKGROUND

Postoperative pain remains a significant challenge following laparoscopy. Aerosolized intraperitoneal local anesthetic (AILA) is a novel method to deliver local anesthetic. The aim was to evaluate aerosolized ropivacaine in pain management following laparoscopic Nissen fundoplication (LNF) and cholecystectomy (LC).

METHODS

This prospective randomized double-blinded placebo-controlled trial enrolled consecutive patients undergoing LNF and LC. The treatment group (TG) received intraperitoneal ropivacaine (5 mL 1 % Naropin(®)) at CO2 insufflation via the AeroSurge(®) aerosolizer device through the camera port. The control group (CG) received 5 mL of saline in the same manner. Postoperative shoulder tip pain at rest 6 h postoperatively was the primary study endpoint, with secondary endpoints of shoulder and abdominal pain within the first 24 h, recovery room stay, hospital stay, and postoperative analgesia use. Pain scores were collected using the Verbal Rating Score.

RESULTS

Eighty-seven patients were included in the final analysis (TG n = 40, CG n = 47). There was no significant difference between CG and TG at the primary endpoint. In the LC group, AILA significantly reduced shoulder tip pain at rest at 10 (p = 0.030) and 30 min (p = 0.040) and shoulder tip pain on movement at 10 (p = 0.030) and 30 min (p = 0.037). In the LNF group, AILA significantly reduced postoperative abdominal pain at rest at 6 h (p = 0.009). AILA reduced overall incidence of shoulder tip pain in the LC group (11.8 vs. 57.9 %, p = 0.004).

CONCLUSION

This study did not demonstrate a significant difference between TG and CG in the primary endpoint, pain at 6 h postoperatively.

Postoperative Analgesia after Laparoscopic Ovarian Cyst Resection: Double-blind Multicenter Randomized Control Trial Comparing Intraperitoneal Nebulization and Peritoneal Instillation of Ropivacaine

STUDY OBJECTIVE

To compare the effects of local anesthetic intraperitoneal nebulization with intraperitoneal instillation during laparoscopic ovarian cystectomy on postoperative morphine consumption and pain.

DESIGN

Multicenter, randomized, case-control trial.

DESIGN CLASSIFICATION

Canadian Task Force Classification I.

SETTING

University hospitals in Italy.

PATIENTS

One hundred forty patients scheduled for laparoscopic ovarian cystectomy.

INTERVENTIONS

Patients were randomized to receive either nebulization of ropivacaine 150 mg before surgery or instillation of ropivacaine 150 mg before surgery. Nebulization was performed using the Aeroneb Pro device (Aerogen, Galway, Ireland).

MEASUREMENTS AND MAIN RESULTS

One hundred forty patients were enrolled, and 123 completed the study. There was no difference between the 2 groups in average morphine consumption (7.3 ± 7.5 mg in the nebulization group vs 9.2 ± 7.2 mg in the instillation group; p = .17). Eighty-two percent of patients in the nebulization group required morphine compared with 96% in the instillation group (p < .05). Patients receiving nebulization had a lower dynamic Numeric Ranking Scale compared with those in the instillation group in the postanesthesia care unit postanesthesia care unit and 4 hours after surgery (p < .05). Ten patients (15%) in the nebulization group experienced shivering in the postanesthesia care unit compared with 2 patients (4%) in the instillation group (p = .035).

CONCLUSION

Nebulization of ropivacaine prevents the use of morphine in a significant proportion of patients, reduced postoperative pain during the first hours after surgery, and was associated with a higher incidence of postoperative shivering when compared with instillation.

Effects of peritoneal ropivacaine nebulization for pain control after laparoscopic gynecologic surgery

STUDY OBJECTIVE

To evaluate the effects of peritoneal cold nebulization of ropivacaine on pain control after gynecologic laparoscopy.

DESIGN

Evidence obtained from a properly designed, randomized, double-blind, placebo-controlled trial (Canadian Task Force classification I).

SETTING

Tertiary care center.

PATIENTS

One hundred thirty-five women with American Society of Anesthesiologists disease classified as ASA I-III who were scheduled to undergo operative laparoscopy.

INTERVENTION

Patients were randomized to receive either nebulization of 30 mg ropivacaine before surgery (preoperative group), nebulization of 30 mg ropivacaine after surgery (postoperative group), instillation of 100 mg ropivacaine before surgery (instillation group), or instillation of saline solution (control group). Nebulization was performed using the Aeroneb Pro device.

MEASUREMENT AND MAIN RESULTS

Pain scores, morphine consumption, and ambulation time were collected in the post-anesthesia care unit and at 4, 6, and 24 hours postoperatively. One hundred eighteen patients completed the study. Patients in the preoperative group reported lower pain Numeric Ranking Scale values compared with those in the control group (net difference 2 points; 95% confidence interval [CI], 0.3-3.1 at 4 hours, 1-3 at 6 hours, and 0.7-3 at 24 hours; p = .01) Patients in the preoperative group consumed significantly less morphine than did those in the control group (net difference 7 mg; 95% CI, 0.7-13; p = .02). More patients who received nebulization walked without assistance within 12 hours after awakening than did those in the instillation and control groups (net difference 15%; 95% CI, 6%-24%; p = .001).

CONCLUSIONS

Cold nebulization of ropivacaine before surgery reduced postoperative pain and morphine consumption and was associated with earlier walking without assistance.

Total systemic ropivacaine concentrations following aerosolized intraperitoneal delivery using the AeroSurge

STUDY OBJECTIVE

To evaluate intraperitoneal ropivacaine delivery with the AeroSurge device in the clinical setting and to evaluate the total systemic ropivacaine levels achieved following delivery of 50 mg of aerosolized ropivacaine.

DESIGN

Preliminary, prospective, nonrandomized study.

SETTING

Operating room of a university hospital.

PATIENTS

5 consecutive ASA physical status 1 and 2 patients undergoing elective laparoscopic Nissen fundoplication or cholecystectomy.

INTERVENTION

Five mL of 1% ropivacaine was delivered through the 10 mm port using the AeroSurge device at peritoneal insufflation.

MEASUREMENTS

Venous blood samples were collected and total ropivacaine concentration was determined using liquid chromatography-mass spectrometry.

MAIN RESULTS

The AeroSurge device delivered ropivacaine, visible as mist within the peritoneal cavity. Peak concentration (Cmax) was attained between 10 and 30 minutes following the end of aerosolized ropivacaine delivery. At no stage did any level approach toxic levels.

CONCLUSIONS

This preliminary study confirms that aerosolized intraperitoneal local anesthetic is feasible, with ropivacaine concentrations remaining within safe levels.

Intraperitoneal nebulization of ropivacaine for pain control after laparoscopic cholecystectomy: a double-blind, randomized, placebo-controlled trial

BACKGROUND

Intraperitoneal local anaesthetic nebulization is a relatively novel approach to pain management after laparoscopic surgery. This randomized, double-blind, placebo-controlled trial evaluated the effects of intraperitoneal ropivacaine nebulization on pain control after laparoscopic cholecystectomy.

METHODS

Patients undergoing laparoscopic cholecystectomy were randomized to receive intraperitoneal nebulization of ropivacaine 1% (3 ml) before surgical dissection and normal saline 3 ml at the end of surgery (preoperative nebulization group); intraperitoneal nebulization of normal saline 3 ml before surgical dissection and ropivacaine 1% (3 ml) at the end of surgery (postoperative nebulization group); or intraperitoneal nebulization of normal saline 3 ml before surgical dissection and at the end of surgery (placebo group). Intraperitoneal nebulization of ropivacaine or saline was performed using the Aeroneb Pro(®) device. Anaesthetic and surgical techniques were standardized. The degree of pain on deep breath or movement, incidence of shoulder pain, morphine consumption, and postoperative nausea and vomiting were collected in the post-anaesthesia care unit and at 6, 24, and 48 h after surgery.

RESULTS

Compared with placebo, ropivacaine nebulization significantly reduced postoperative pain (-33%; Cohen's d 0.64), referred shoulder pain (absolute reduction -98%), morphine requirements (-41% to -56% Cohen's d 1.16), and time to unassisted walking (up to -44% Cohen's d 0.9) (P<0.01). There were no differences in pain scores between ropivacaine nebulization groups.

CONCLUSIONS

Ropivacaine nebulization before or after surgery reduced postoperative pain and referred shoulder pain after laparoscopic cholecystectomy. Furthermore, ropivacaine nebulization reduced morphine requirements and allowed earlier mobility.

Description of a novel approach for intraperitoneal drug delivery and the related device

BACKGROUND

Two significant limitations of intraperitoneal drug therapy are limited drug distribution and poor penetration into peritoneal nodules. A possible solution is the application of the so-called "therapeutic pneumoperitoneum," taking advantage of the gaseous nature and the pressure of capnoperitoneum during laparoscopy. Our objective was to develop a device able to apply such therapeutic pneumoperitoneum.

METHODS

The technology presented here is a spraying device and can be introduced through a trocar. It is driven by mechanical pressure and consists of an injector, a line, and a nozzle. An in vivo experimental study was performed in five pigs. A transvaginal cholecystectomy was performed. At the end of the procedure, a standard dose of methylene blue was sprayed/infused into the abdominal cavity for 30 min (4 test animals w/therapeutic pneumoperitoneum (12 mmHg CO(2)) and 1 control animal w/conventional lavage (2 l intra-abdominal volume with extracorporeal circulation)). At the end of the procedure, all animals were autopsied and the peritoneum was analyzed. Outcome criteria were: (1) drug distribution (as assessed by the stained peritoneal surface at autopsy), and (2) diffusion into the peritoneum (presence or not of macroscopic staining of the outer aspect of the peritoneum immediately after surgery).

RESULTS

Stained peritoneal surface was larger after aerosol application compared with peritoneal lavage, and staining more intense. Hidden peritoneal surfaces and the anterior abdominal wall were stained only in the aerosol group. In contrast to peritoneal lavage, the outer aspect of peritoneal membrane was immediately stained after pressurized spraying.

CONCLUSIONS

This device and the related approach significantly improve both distribution and penetration of a test substance into the peritoneal cavity in a large animal model. This might be a significant progress in treating intraperitoneal disease, in particular peritoneal carcinomatosis.

Intraperitoneal ropivacaine nebulization for pain management after laparoscopic cholecystectomy: a comparison with intraperitoneal instillation

BACKGROUND

Studies evaluating intraperitoneal local anesthetic instillation for pain relief after laparoscopic procedures have reported conflicting results. In this randomized, double-blind study we assessed the effects of intraperitoneal local anesthetic nebulization on pain relief after laparoscopic cholecystectomy.

METHODS

Patients undergoing elective laparoscopic cholecystectomy were randomly assigned to receive either instillation of ropivacaine 0.5%, 20 mL after induction of the pneumoperitoneum, or nebulization of ropivacaine 1%, 3 mL before and after surgery. Anesthetic and surgical techniques were standardized. Degree of pain at rest and on deep breathing, incidence of shoulder pain, morphine consumption, unassisted walking time, and postoperative nausea and vomiting were evaluated at 6, 24, and 48 hours after surgery.

RESULTS

Of the 60 patients included, 3 exclusions occurred for conversion to open surgery. There were no differences between groups in pain scores or in morphine consumption. No patients in the nebulization group presented significant shoulder pain in comparison with 83% of patients in the instillation group (absolute risk reduction -83, 95% CI -97 to -70, P<0.001). Nineteen (70%) patients receiving nebulization walked without assistance within 12 hours after surgery in comparison with 14 (47%) patients receiving instillation (absolute risk reduction -24, 95% CI -48 to 1, P=0.04). One (3%) patient in the instillation group vomited in comparison with 6 (22%) patients in the nebulization group (absolute risk reduction -19%, 95% CI -36 to -2, P=0.03).

CONCLUSIONS

Intraperitoneal ropivacaine nebulization was associated with reduced shoulder pain and unassisted walking time but with an increased incidence of postoperative vomiting after laparoscopic cholecystectomy.

Systematic review and meta-analysis of intraperitoneal local anaesthetic for pain reduction after laparoscopic gastric procedures

BACKGROUND

With the advent of minimally invasive gastric surgery, visceral nociception has become an important area of investigation as a potential cause of postoperative pain. A systematic review and meta-analysis was carried out to investigate the clinical effects of intraperitoneal local anaesthetic (IPLA) in laparoscopic gastric procedures.

METHODS

Comprehensive searches were conducted independently without language restriction. Studies were identified from the following databases from inception to February 2010: Cochrane Central Register of Controlled Trials, the Cochrane Library, MEDLINE, PubMed, Embase and CINAHL. Relevant meeting abstracts and reference lists were searched manually. Appropriate methodology according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was adhered to.

RESULTS

Five randomized controlled trials in laparoscopic gastric procedures were identified for review. There was no significant heterogeneity between the trials (χ(2) = 10·27, 10 d.f., P = 0·42, I(2) = 3 per cent). Based on meta-analysis of trials, there appeared to be reduced abdominal pain intensity (overall mean difference in pain score -1·64, 95 per cent confidence interval (c.i.) -2·09 to -1·19; P < 0·001), incidence of shoulder tip pain (overall odds ratio 0·15, 95 per cent c.i. 0·05 to 0·44; P < 0·001) and opioid use (overall mean difference -3·23, -4·81 to -1·66; P < 0·001).

CONCLUSION

There is evidence in favour of IPLA in laparoscopic gastric procedures for reduction of abdominal pain intensity, incidence of shoulder pain and postoperative opioid consumption.

Intraperitoneal use of local anesthetic in laparoscopic cholecystectomy: systematic review and metaanalysis of randomized controlled trials

BACKGROUND/PURPOSE

With the advent of minimally invasive gallbladder surgery, and now with natural orifice techniques emerging, visceral nociception has been neglected as a cause of postoperative pain. A systematic review and metaanalysis was carried out to investigate the use of intraperitoneal local anesthetic (IPLA) in order to assess its role in laparoscopic cholecystectomy (LC). The aim of this systematic review was to appraise the clinical effects of this modality.

METHODS

Comprehensive searches were conducted independently without language restriction. Studies were identified from the following databases from inception to September 2009: Cochrane Central Register of Controlled Trials (CENTRAL/CCTR), Cochrane Library, Medline, PubMed, Excerpta Medica Database (EMBASE), and Cumulative Index to Nursing and Allied Health Literature (CINHAL). Relevant meeting abstracts and reference lists were manually searched. Data analysis was performed using Review Manager Version 5.0 software.

RESULTS

Thirty randomized controlled trials were identified for review. The clinical heterogeneity of IPLA use was high. However, there appeared to be reduced pain, opioid use, and need for rescue analgesia, and reduced postoperative cortisol and glucose responses.

CONCLUSION

There is evidence in favor of IPLA in LC. Further trials of this modality in LC are not needed as these are unlikely to reduce clinical heterogeneity. IPLA should be trialled as future minimally invasive surgical techniques approach.

Changes in core temperature during peritoneal insufflation: comparison of two CO2 humidification devices in pigs

BACKGROUND

Various modifications of the physical status of CO2 have been used to reduce hypothermia caused by flow of insufflating gas. This animal study aimed to investigate the effects on core temperature, of insufflation with CO2 using two different humidification devices: unheated, humidified CO2 using the Modified-Aeroneb system (Nektar, San Carlos, CA) and warmed, humidified CO2 using the HME-Booster (Medisize, Hillegom, The Netherlands).

METHODS

We undertook a prospective four-session study on a homogeneous group of four pigs. After general anesthesia, all animals were treated successively with the following protocols in a randomized order at 8-d intervals: Control (no pneumoperitoneum), Standard (unheated, unhumidified CO2), Modified-Aeroneb (unheated, humidified CO2 by cold nebulization), HME-Booster (heated, humidified CO2). The core temperature of the animals was recorded every 10 min.

RESULTS

The temperature decrease is significantly influenced by time (P=0.0001; ANOVA), by the insufflation method (P=0.01), and by the interaction between time and the insufflation method (P=0.0001). The method of contrasts showed the following results:--The temperature decrease in the Standard group and HME-Booster group became greater than in the Control group after 40 min (P=0.02)--The temperature decrease in the Modified-Aeroneb group became greater than in the Control group after 100 min (P=0.04)--The temperature decrease in the Modified-Aeroneb group was less than in the HME-Booster group after 40 min (P=0.04) and less than in the Standard group after 60 min (P=0.01)--The temperature decrease in the Standard group was greater than in the HME-Booster group after 160 min (P=0.005).

CONCLUSIONS

Compared with the HME-Booster system, the Modified-Aeroneb is at least as effective in limiting the drop in core temperature during laparoscopic insufflation.

The pharmacokinetics of ropivacaine after intraperitoneal administration: instillation versus nebulization

BACKGROUND

Intraperitoneal local anesthetic administration provides perioperative analgesia during laparoscopic procedures. We compared the pharmacokinetics of intraperitoneal ropivacaine administered by instillation or nebulization.

METHODS

A crossover study was performed on 5 pigs under standardized general anesthesia with a carbon dioxide pneumoperitoneum of 12 mm Hg for 1 hour. Each animal, acting as its own control, was studied twice with an 8-day interval and received, in a randomized sequence, 3 mg/kg ropivacaine either by intraperitoneal instillation at the time of pneumoperitoneum exsufflation or by continuous nebulization in the carbon dioxide insufflation tubing. Arterial blood samples were taken every 10 minutes up to 120 minutes, and then hourly up to 6 hours. Ropivacaine concentrations were measured using high-performance liquid chromatography with ultraviolet-visible detection. The plasma-free fraction was evaluated after plasma ultracentrifugation. Pharmacokinetic parameters were calculated using both noncompartmental and compartmental analysis. The mean values were compared using the Student t test, or Wilcoxon test for paired series.

RESULTS

The data were described by a 1-compartment model for both ropivacaine administration techniques, with a delay of 10 minutes for the nebulization group. The maximal ropivacaine concentrations were 0.96 μg/mL for the nebulization group and 0.92 μg/mL for the instillation group (P = 0.66). The ropivacaine absorption constant was lower in the nebulization group (0.043 vs 0.083 min(-1), P = 0.02). There were no differences in the elimination half-life, elimination constant, mean total body clearance, distribution volume, mean area under the curve, and mean residence time. The free fraction of ropivacaine was also similar in the 2 groups.

CONCLUSIONS

The pharmacokinetic profile of ropivacaine nebulization is similar to direct intraperitoneal instillation, but with a lower absorption rate.

Should the wheel be reinvented in a human study?

Recently, Zimmer and colleagues reported a lack of analgesic efficacy from intraperitoneal nebulization of bupivacaine using the Insuflow device for patients undergoing laparoscopic cholecystectomy. This is not surprising. An in vitro study in 2008 showed that hot evaporation-based devices, similar to Insuflow, are unable to transport drug molecules dissolved in a water solvent. These results are in keeping with the physical principle that hot evaporation enables only evaporation of the solvent (e.g., water) and not of the solute (e.g., bupivacaine). Although this well-conducted human study has a defendable medical justification and a high theoretical interest, it is not acceptable to choose a human model for an experimental study that attempts to explore a question whose answer has already been published years before in a bench setting.