Effect of Heated and Humidified Carbon Dioxide on Patients After Laparoscopic Procedures: A Meta-analysis

Impact of Acetazolamide on Perioperative Pain Control in Robotic Assisted Laparoscopic Prostatectomy

OBJECTIVE

To evaluate the efficacy of peri-operative acetazolamide for pain control in robotic assisted laparoscopic prostatectomy (RALP). Prior studies have demonstrated that preoperative acetazolamide decreased postoperative referred pain in the postsurgical period for laparoscopic procedures. The proposed mechanism is acetazolamide mediated inhibition of carbonic anhydrase, thereby preventing formation of carbonic acid and subsequent peritoneal acidosis with referred pain. This has yet to be demonstrated in the setting of RALP.

METHODS AND MATERIALS

Patients undergoing RALP were randomized to receive either preoperative saline or acetazolamide prior to the procedure. Overall pain scores were recorded at multiple time points post operatively, as well as total morphine equivalents administered for adjunctive pain control.

RESULTS

Thirty-one patients were included in the study: 16 patients (51.6%) received perioperative acetazolamide, and 15 patients (48.4%) received perioperative saline as placebo. Overall pain scores were similar for patients receiving acetazolamide compared to placebo at various time points: first responsive (3.5 ± 3.1 vs 4.1 ± 1.7, P = .28), immediately prior to leaving PACU (2.8 ± 2.9 vs 2.9 ± 2.9, P = .48), at 4 hours post-procedure (3.1 ± 3.0 vs 2.9 ± 1.8, P = .362), or at 24 hours post-procedure (2.3 ± 1.7 vs 2.2 ± 1.6, P = .5). Shoulder tip pain was not present in either cohort. No statistically significant difference was observed for total morphine equivalents delivered between acetazolamide and placebo (17.3 vs 20.5, P= .2, respectively).

CONCLUSION

Acetazolamide does not appear to impact overall pain or shoulder tip pain in the observed cohort of patients undergoing RALP.

Evaluating the concept of gas‑based intraperitoneal hyperthermia beyond 43˚C in the treatment of peritoneal metastasis: A pilot study

While hyperthermic intraperitoneal applications have demonstrated high efficacy in treating peritoneal metastases (PM), these applications are limited to temperatures of 41-43˚C to prevent a harmful increase in core temperature. However, since gaseous substances display low specific heat capacities, gas-based hyperthermia could potentially increase surface temperatures without affecting the body's core temperature. To the best of our knowledge, the present study is the first to explore the in vivo feasibility of gas-based hyperthermia via spatial and time-based distribution. In the present study, a temperature-isolated, abdominal box model was created with fresh peritoneal tissue exposed to continuous high-volume airflow temperatures ranging between 47 and 69˚C. Heat conduction within the peritoneal tissues was measured using temperature microsensors. Temperature build-up at different time points during the procedure was calculated and the safest option to perform gas-based intraperitoneal hyperthermia beyond 43˚C was identified using an in vivo swine model. In subsequent experiments, viability and cytotoxicity of HT-29 colon cancer cells were measured following short-term hyperthermia. The present study demonstrated that the application of gas-based intraperitoneal hyperthermia with temperatures up to 50˚C is possible without increasing the core temperature to harmful levels. Gas-based intraperitoneal hyperthermia can induce a histological reaction on the peritoneal surface, and it can also result in decreased viability and increased cytotoxicity of HT-29 cells. The concept of extreme hyperthermia may be of great clinical importance as it could significantly increase local cytotoxicity in PM without increasing the body's core temperature. Further studies are required to investigate the benefits, as well as the restrictions, of this novel concept.

The effects of CO2 pneumoperitoneum at different temperature and humidity on hemodynamic and respiratory parameters and postoperative pain in gynecological laparoscopic surgery: A prospective randomized controlled study

BACKGROUND

It is recommended to heat and humidity CO₂ in laparoscopic surgery to prevent postoperative pain and hypothermia but information about its effects on hemodynamic and respiratory parameters is limited. We aimed to investigate the effects of standard and heated-humidified CO₂ on hemodynamic and respiratory parameters, body temperature and pain in healthy patients.

METHODS

One hundred patients who underwent total laparoscopic hysterectomy for benign pathology were divided into two groups: Group CD (cold-dry) patients were administered standard CO₂, while Group HH (heated-humidified) patients were administered 95% humidified insufflation at 37 °C. Hemodynamic and respiratory parameters, body temperature, pain score and blood count parameters were recorded.

RESULTS

A total of 96 patients were included in the study, taken from the 100 patients. Group HH (n:47) had only higher systolic blood pressure at 75, mean blood pressure at 50 and 55 and a lower heart rate between 15 and 45 min (p:0.049, 0.037, 0.013 respectively). Pain score, morphine consumption, end-tidal CO₂ and arterial blood gas values were not different between the groups, with only body temperature from 40 min and minimum value being significantly higher (at a difference of 0.86-1.04 °C) in Group HH. Postoperative leukocyte, neutrophil and NLR (neutrophil-leukocyte ratio) were found to be higher in this group (p < 0.05).

CONCLUSION

It has been found that both standard and heated-humidified CO₂do not constitute a problem in terms of hemodynamic and respiratory parameters in healthy patients. The heated-humidified CO₂group had only a higher core body temperature and inflammatory response.

TRIAL REGISTRATION

NCT04508387.

Electrostatic Precipitation in Low Pressure Laparoscopic Hysterectomy and Myomectomy

BACKGROUND AND OBJECTIVE

The purpose of this study was to evaluate the impact of using electrostatic precipitation to manage the surgical plume during low pressure laparoscopic gynecologic procedures.

METHODS

This was a prospective, blinded, randomized controlled study of women with a clinical indication for laparoscopic hysterectomy (n = 30) or myomectomy (n = 5). Patients were randomized to either use electrostatic precipitation (EP) during the procedure, or not (No EP, hysterectomy group only).

RESULTS

Low pressure surgery could be undertaken in 87% of hysterectomy cases (13/15) when using EP to manage the surgical plume, compared to only 53% (8/15) in the No EP group. Overall average rating of the visual field was excellent with EP vs fair for No EP. Average CO2 consumption was reduced by 29% when using EP (16.7L vs 23.5L, p = 0.152). The average number of procedural pauses to vent smoke was lower with EP than the No EP group (1.5 per case vs. 3.7 per case, p = 0.005). Average procedure duration for the EP vs No EP group was 40.5 min vs. 46.9 min (p = 0.987). There were no measurable differences between groups for body temperature, end-tidal CO2, and discharge pain scores. In myomectomy, all five cases could be performed at low pressure, with an excellent visual field rating.

CONCLUSION

Electrostatic precipitation enhances low pressure laparoscopic hysterectomy and myomectomy. This was achieved by minimizing interruptions to surgery and exchange of CO2; providing a clear visual field throughout the procedure; and eliminating surgical smoke at the site of origin.

Pain after laparoscopic surgery: Focus on shoulder-tip pain after gynecological laparoscopic surgery

Laparoscopy, one of minimally invasive procedures, is a commonly used procedure in diagnosis and management of various kinds of clinical problems, including gynecologic organ-related diseases. Compared with conventional exploratory laparotomy, the benefits of laparoscopic surgery include reduction of surgical wound, decreasing in postoperative pain, shortening hospital stay, rapid recovery, and a better cosmetic result. However, there are still up to 80% of patients after laparoscopic surgery complaining of high levels of pain and needing pain relief. Postlaparoscopic pain can be separated into distinct causes, such as surgical trauma- or incision wound-associated inflammatory change, and pneumoperitoneum (carbon dioxide [CO2])-related morphological and biochemical changes of peritoneum and diaphragm. The latter is secondary to irritation, stretching, and foreign body stimulation, leading to phrenic neuropraxia and subsequent shoulder-tip pain (STP). STP is the most typical unpleasant experience of patients after laparoscopic surgery. There are at least 11 strategies available to attempt to decrease postlaparoscopic STP, including (1) the use of an alternative insufflating gas in place of CO2, (2) the use of low-pressure pneumoperitoneum in place of standard-pressure pneumoperitoneum, (3) the use of warmed or warmed and humidified CO2, (4) gasless laparoscopy, (5) subdiaphragmatic intraperitoneal anesthesia, (6) local intraperitoneal anesthesia, (7) actively expelling out of gas, (8) intraperitoneal drainage, (9) fluid instillation, (10) pulmonary recruitment maneuvers, and (11) others and combination. The present article is limited in discussing postlaparoscopic STP. We extensively review published articles to provide a better strategy to reduce postlaparoscopic STP.

A Randomized Controlled Trial Comparing Laparoscopic Lens Defogging Techniques through Simulation Model

Context

Current literature demonstrates a lack of comparative studies regarding effective techniques for reducing laparoscopic lens fogging.

Aim

Our primary objective is to determine the efficacy of various laparoscopic defogging techniques (LDT) through a randomized controlled trial that employs a novel simulation model of the abdominopelvic cavity.

Settings and Design

This study was conducted at academic community hospital. This study design was a randomized controlled trial through simulation.

Subjects and Methods

A chamber was constructed that simulated the abdominopelvic cavity. We used 5 and 10 mm 0° laparoscopes. A 10 cm visual analog scale was developed to assign visual clarity (VC) scores. The 10 cm mark indicated perfect VC. We employed the following LDTs: (1) glove warming (GLOVE), (2) surfactant solution (Fog Reduction and Elimination Device [FRED]), (3) chlorhexidine solution (SOAP), (4) warm saline (SALINE), and (5) control. Three observers were blinded to the LDT used. Primary outcomes included VC scores at designated time intervals (5, 30, and 60 s) for each LDT. A minimum of 10 observations per time interval were required to achieve adequate power based on a 2.5 cm difference in VC scores.

Results

For the 10 mm laparoscope, FRED, SOAP, and SALINE had a VC score at 60 s (VC60) higher than control (4.8 ± 2.2, 7.8 ± 0.8, 7.9 ± 0.7 vs. 2.4 ± 0.72, P < 0.05). Both SOAP and SALINE VC60 scores were higher than FRED (7.8 ± 0.8, 7.9 ± 0.7 vs. 4.8 ± 2.2, P < 0.05). No differences were noted in VC60 scores between control and GLOVE (2.4 ± 0.72 vs. 3.1 ± 2.2, P > 0.05) and between SOAP and SALINE (7.8 ± 0.8 vs. 7.9 ± 0.7, P > 0.05). Similar results were noted with the 5 mm laparoscope.

Conclusions

Common LDTs such as SALINE and SOAP were more effective than FRED, while GLOVE was no different than control. These results demonstrate that the use of effective LDTs can potentially translate into improved patient care and operative outcomes during surgery.

Increased visceral tissue perfusion with heated, humidified carbon dioxide insufflation during open abdominal surgery in a rodent model

Tissue perfusion during surgery is important in reducing surgical site infections and promoting healing. This study aimed to determine if insufflation of the open abdomen with heated, humidified (HH) carbon dioxide (CO2) increased visceral tissue perfusion and core body temperature during open abdominal surgery in a rodent model. Using two different rodent models of open abdominal surgery, visceral perfusion and core temperature were measured. Visceral perfusion was investigated using a repeated measures crossover experiment with rodents receiving the same sequence of two alternating treatments: exposure to ambient air (no insufflation) and insufflation with HH CO2. Core body temperature was measured using an independent experimental design with three treatment groups: ambient air, HH CO2 and cold, dry (CD) CO2. Visceral perfusion was measured by laser speckle contrast analysis (LASCA) and core body temperature was measured with a rectal thermometer. Insufflation with HH CO2 into a rodent open abdominal cavity significantly increased visceral tissue perfusion (2.4 perfusion units (PU)/min (95% CI 1.23-3.58); p<0.0001) compared with ambient air, which significantly reduced visceral blood flow (-5.20 PU/min (95% CI -6.83- -3.58); p<0.0001). Insufflation of HH CO2 into the open abdominal cavity significantly increased core body temperature (+1.15 ± 0.14°C) compared with open cavities exposed to ambient air (-0.65 ± 0.52°C; p = 0.037), or cavities insufflated with CD CO2 (-0.73 ± 0.33°C; p = 0.006). Abdominal visceral temperatures also increased with HH CO2 insufflation compared with ambient air or CD CO2, as shown by infrared thermography. This study reports for the first time the use of LASCA to measure visceral perfusion in open abdominal surgery and shows that insufflation of open abdominal cavities with HH CO2 significantly increases visceral tissue perfusion and core body temperature.

Surgical stress response and promotion of metastasis in colorectal cancer: a complex and heterogeneous process

Surgery remains the curative treatment modality for colorectal cancer in all stages, including stage IV with resectable liver metastasis. There is emerging evidence that the stress response caused by surgery as well as other perioperative therapies such as anesthesia and analgesia may promote growth of pre-existing micro-metastasis or potentially initiate tumor dissemination. Therapeutically targeting the perioperative period may therefore reduce the effect that surgical treatments have in promoting metastases, for example by combining β-adrenergic receptor antagonists and cyclooxygenase-2 (COX-2) inhibitors in the perioperative setting. In this paper, we highlight some of the mechanisms that may underlie surgery-related metastatic development in colorectal cancer. These include direct tumor spillage at the time of surgery, suppression of the anti-tumor immune response, direct stimulatory effects on tumor cells, and activation of the coagulation system. We summarize in more detail results that support a role for catecholamines as major drivers of the pro-metastatic effect induced by the surgical stress response, predominantly through activation of β-adrenergic signaling. Additionally, we argue that an improved understanding of surgical stress-induced dissemination, and more specifically whether it impacts on the level and nature of heterogeneity within residual tumor cells, would contribute to the successful clinical targeting of this process. Finally, we provide a proof-of-concept demonstration that ex-vivo analyses of colorectal cancer patient-derived samples using RGB-labeling technology can provide important insights into the heterogeneous sensitivity of tumor cells to stress signals. This suggests that intra-tumor heterogeneity is likely to influence the efficacy of perioperative β-adrenergic receptor and COX-2 inhibition, and that ex-vivo characterization of heterogeneous stress response in tumor samples can synergize with other models to optimize perioperative treatments and further improve outcome in colorectal and other solid cancers.

Reduction in surgical fog with a warm humidified gas management protocol significantly shortens procedure time in pediatric robot-assisted laparoscopic procedures

INTRODUCTION

The adoption of robot-assisted laparoscopic (RAL) procedures in the field of urology has occurred rapidly, but is, to date, without pediatric-specific instrumentation. Surgical fog is a significant barrier to safe and efficient laparoscopy. This appears to be a significant challenge when adapting three-dimensional 8.5-mm scopes to use in pediatric RAL surgery. The objective of the present study was to compare matched controls from a prospectively collected database to procedures that were performed utilizing special equipment and a protocol to minimize surgical fog in pediatric RAL procedures.

METHODS

A prospectively collected database of all patients who underwent RAL pediatric urology procedures was used to compare: procedure, age, sex, American Society of Anesthesiologists score, weight, console time, number of times the camera was removed to clean the lens during a procedure, length of hospital stay, and morphine equivalents required in the postoperative period. A uniquely developed protocol was used, it consisted of humidified (95% relative humidity) and warmed CO₂ gas (95 °F) insufflation via Insuflow® on a working trocar, with active smoke evacuation via PneuVIEW®XE on the opposite working trocar with a gas pass through of 3.5-5 l/min. The outcomes were compared with matched controls (Summary Fig).

RESULTS

The novel gas protocol was utilized in 13 procedures (five pyeloplasties, two revision pyeloplasties, three ureteroureterostomies (UU), three nephrectomies) and compared with 13 procedures (six pyeloplasties, one revision pyeloplasty, three UU, three nephrectomies) prior to the protocol development. There was no statistical difference in age (P = 0.78), sex (P = 0.11), ASA score (P = 1.00) or weight (P = 0.69). There were no open conversions, ≥Grade 2 Clavien complications, or readmissions within 30 days in either group.

CONCLUSIONS

This novel gas protocol yielded a statistically significant reduction in procedure time, by decreasing the number of times the camera was required to be pulled during the case by more than five occurrences, and saved approximately 35 min on average per case.

Managing Postoperative Pain After Minimally Invasive Gynecologic Surgery in the Era of the Opioid Epidemic

In this review, we examine the evidence behind nonopioid medication alternatives, peripheral nerve blocks, surgical techniques, and postoperative recovery protocols that can help minimize and effectively treat postoperative pain after minimally invasive gynecologic surgery (MIGS). Because of the depth and heterogeneity of the data, a narrative review was performed of reported interventions. A comprehensive review was performed of PubMed, Embase, and the Cochrane Database with a focus on randomized controlled trials. In the absence of literature specific to benign gynecology, similar specialty or procedural data were reviewed. A variety of nonopioid medications, surgical techniques, and postoperative recovery protocols have shown significant improvements in postoperative pain after gynecologic surgery. Nonopioid medication options that are beneficial include acetaminophen, nonsteroidal anti-inflammatories, and antiepileptics. Incision infiltration with local anesthesia also significantly reduces pain. Surgically, minimally invasive approaches, reducing the laparoscopic trocar size to <10 mm, and evacuating the pneumoperitoneum at the end of the case all have significant benefits. Lastly, enhanced recovery pathways show promise in reducing pain after MIGS. By using a multimodal approach, minimally invasive gynecologic surgeons can help to minimize and manage postoperative pain with less reliance on opioid pain medications.

Warm and Humidified Versus Cold and Dry CO2 Pneumoperitoneum in Minimally Invasive Colon Resection: A Randomized Controlled Trial

INTRODUCTION

Peritoneal insufflation with warm-humidified (WH) CO₂ gas during minimally invasive surgical procedures is purported to prevent hypothermia and peritoneal desiccation and is associated with decreased postoperative IL-6 levels. This randomized study's purpose was to determine the clinical impact of WH versus cold-dry (CD) CO₂ in minimally invasive colon resection (MICR), and to assess perioperative plasma levels of IL-6, TIMP-1, sVEGF-R1, and HSP-70 after MICR.

METHODS

Operative and short-term clinical data plus perioperative blood samples were collected on MICR patients randomized to receive either WH (36.7°C, 95% humidity) or CD (room temperature, 0% humidity) CO₂ perioperatively. Peritoneal biopsies were taken at the start and end of surgery. Outcomes tracked included core temperature, postoperative in-hospital pain levels, analgesia requirements, and standard recovery parameters. Preoperative and postoperative days (PODs) 1 and 3 plasma protein levels were determined via ELISA.

RESULTS

A total of 101 patients were randomized to WH CO₂ (50) or CD CO₂ (51). The WH group contained more diabetics ( P = .03). There were no differences in indication, minimally invasive surgical method used, or core temperature. Pain scores were similar; however, the WH patients required less narcotics on PODs 1 to 3 ( P < .05), and less ketorolac on PODs 1 and 2 ( P < .03). No differences in length of stay, complication rates, or time to flatus/diet tolerance were noted. Plasma levels of the 4 proteins were similar postoperatively. Though insignificant, the WH group had less marked histologic changes on "end-of-case" peritoneal biopsies.

CONCLUSION

This study found significantly lower pain medication requirements for PODs 1 to 3 for the WH group; however, because there were no differences in the pains scores between the groups, firm conclusions regarding WH CO₂ cannot be made.

Association between intraabdominal pressure during gynaecologic laparoscopy and postoperative pain

PURPOSE

Laparoscopy is nowadays a well-established surgical method and plays a main role in an ever-increasing range of indications in gynaecology. High-quality studies of surgical techniques are necessary to improve the quality of patient care. The present study aims at evaluating postoperative pain after gynaecological laparoscopy depending on the intraoperative CO₂ pressure.

METHODS

In a prospective, monocentric, randomized single-blind study at the Department of Gynaecology and Obstetrics at the Hannover Medical School, we include patients scheduled for different laparoscopic procedures. Randomization of the intraoperative CO₂ pressure was carried out in six groups. Pain was assessed the day after surgery by the blinded nurse using a visual analogue scale.

RESULTS

550 patients were included in the period from May 2013 to January 2016. The analysis of the per protocol population PPP (n = 360) showed no statistically significant difference between the six intervention groups with regard to mean postoperative pain perception. In direct comparison between two groups, an intraoperative CO₂ pressure of 15 mmHg was associated with a significant higher pain score than a pressure of 12 mmHg. The difference was 7.46 mm on a 10 cm VAS.

CONCLUSIONS

The results of our study indicate that a CO₂ pressure of 12 versus 15 mmHg can be advantageous. However, the clinical relevance remains unclear due to the low difference in pain. The additional benefit of an even lower pressure of 10 or 8 mmHg cannot be reliably assessed; we found signs of poor visibility conditions in these low pressure groups.

Five year follow-up of a randomized controlled trial on warming and humidification of insufflation gas in laparoscopic colonic surgery--impact on small bowel obstruction and oncologic outcomes

Warming and humidification of insufflation gas has been shown to reduce adhesion formation and tumor implantation in the laboratory setting, but clinical evidence is lacking. We aimed to test the hypothesis that warming and humidification of insufflation CO2 would lead to reduced adhesion formation, and improve oncologic outcomes in laparoscopic colonic surgery. This was a 5-year follow-up of a multicenter, double-blinded, randomized, controlled trial investigating warming and humidification of insufflation gas. The study group received warmed (37°C), humidified (98%) insufflation carbon dioxide, and the control group received standard gas (19°C, 0%). All other aspects of patient care were standardized. Admissions for small bowel obstruction were recorded, as well as whether management was operative or nonoperative. Local and systemic cancer recurrence, 5-year overall survival, and cancer specific survival rates were also recorded. Eighty two patients were randomized, with 41 in each arm. Groups were well matched at baseline. There was no difference between the study and control groups in the rate of clinical small bowel obstruction (5.7% versus 0%, P 0.226); local recurrence (6.5% versus 6.1%, P 1.000); overall survival (85.7% versus 82.1%, P 0.759); or cancer-specific survival (90.3% versus 87.9%, P 1.000). Warming and humidification of insufflation CO2 in laparoscopic colonic surgery does not appear to confer a clinically significant long term benefit in terms of adhesion reduction or oncological outcomes, although a much larger randomized controlled trial (RCT) would be required to confirm this. ClinicalTrials.gov Trial identifier: NCT00642005; US National Library of Medicine, 8600 Rockville Pike, Bethesda, MD 20894, USA.

Heated insufflation with or without humidification for laparoscopic abdominal surgery

BACKGROUND

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies on heated insufflation have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times.

OBJECTIVES

To determine the effect of heated gas insufflation compared to cold gas insufflation on maintaining intraoperative normothermia as well as patient outcomes following laparoscopic abdominal surgery.

SEARCH METHODS

We searched Cochrane Colorectal Cancer Specialised Register (September 2016), the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2016, Issue 8), Ovid MEDLINE (1950 to September 2016), Ovid Embase (1974 to September 2016), International Pharmaceutical Abstracts (IPA) (September 2016), Web of Science (1985 to September 2016), Scopus, www.clinicaltrials.gov and the National Research Register (1956 to September 2016). We also searched grey literature and cross references. Searches were limited to human studies without language restriction.

SELECTION CRITERIA

Only randomised controlled trials comparing heated (with or without humidification) with cold gas insufflation in adult and paediatric populations undergoing laparoscopic abdominal procedures were included. We assessed study quality in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. Two review authors independently selected studies for the review, with any disagreement resolved in consensus with a third co-author.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed screening of eligible studies, data extraction and methodological quality assessment of the trials. We classified a study as low-risk of bias if all of the first six main criteria indicated in the 'Risk of Bias Assessment' table were assessed as low risk. We used data sheets to collect data from eligible studies. We presented results using mean differences for continuous outcomes and relative risks for dichotomous outcomes, with 95% confidence intervals. We used Review Manager (RevMan) 5.3 software to calculate the estimated effects. We took publication bias into consideration and compiled funnel plots.

MAIN RESULTS

We included 22 studies in this updated analysis, including six new trials with 584 additional participants, resulting in a total of 1428 participants. The risk of bias was low in 11 studies, high in one study and unclear in the remaining studies, due primarily to failure to report methodology for randomisation, and allocation concealment or blinding, or both. Fourteen studies examined intraoperative core temperatures among heated and humidified insufflation cohorts and core temperatures were higher compared to cold gas insufflation (MD 0.31 °C, 95% CI, 0.09 to 0.53, I2 = 88%, P = 0.005) (low-quality evidence). If the analysis was limited to the eight studies at low risk of bias, this result became non-significant but remained heterogeneous (MD 0.18 °C, 95% CI, -0.04 to 0.39, I2= 81%, P = 0.10) (moderate-quality evidence).In comparison to the cold CO2 group, the meta-analysis of the heated, non-humidified group also showed no statistically significant difference between groups. Core temperature was statistically, significantly higher in the heated, humidified CO2 with external warming groups (MD 0.29 °C, 95% CI, 0.05 to 0.52, I2 = 84%, P = 0.02) (moderate-quality evidence). Despite the small difference in temperature of 0.31 °C with heated CO2, this is unlikely to be of clinical significance.For postoperative pain scores, there were no statistically significant differences between heated and cold CO2, either overall, or for any of the subgroups assessed. Interestingly, morphine-equivalent use was homogeneous and higher in heated, non-humidified insufflation compared to cold insufflation for postoperative day one (MD 11.93 mg, 95% CI 0.92 to 22.94, I2 = 0%, P = 0.03) (low-quality evidence) and day two (MD 9.79 mg, 95% CI 1.58 to 18.00, I2 = 0%, P = 0.02) (low-quality evidence). However, morphine use was not significantly different six hours postoperatively or in any humidified insufflation groups.There was no apparent effect on length of hospitalisation, lens fogging or length of operation with heated compared to cold gas insufflation, with or without humidification. Recovery room time was shorter in the heated cohort (MD -26.79 minutes, 95% CI -51.34 to -2.25, I2 = 95%, P = 0.03) (low-quality evidence). When the one and only unclear-risk study was removed from the analysis, the difference in recovery-room time became non-significant and the studies were statistically homogeneous (MD -1.22 minutes, 95% CI, -6.62 to 4.17, I2 = 12%, P = 0.66) (moderate-quality evidence).There were also no differences in the frequency of major adverse events that occurred in the cold or heated cohorts.These results should be interpreted with caution due to some limitations. Heterogeneity of core temperature remained significant despite subgroup analysis, likely due to variations in the study design of the individual trials, as the trials had variations in insufflation gas temperatures (35 ºC to 37 ºC), humidity ranges (88% to 100%), gas volumes and location of the temperature probes. Additionally, some of the trials lacked specific study design information making evaluation difficult.

AUTHORS' CONCLUSIONS

While heated, humidified gas leads to mildly smaller decreases in core body temperatures, clinically this does not account for improved patient outcomes, therefore, there is no clear evidence for the use of heated gas insufflation, with or without humidification, compared to cold gas insufflation in laparoscopic abdominal surgery.

Postoperative hypothermia and surgical site infection following peritoneal insufflation with warm, humidified carbon dioxide during laparoscopic colorectal surgery: a cohort study with cost-effectiveness analysis

Background

Surgical Site Infection (SSI) occurs in 9 % of laparoscopic colorectal surgery. Warming and humidifying carbon dioxide (CO₂) used for peritoneal insufflation may protect against SSI by avoiding postoperative hypothermia (itself a risk factor for SSI). This study aimed to assess the impact of CO₂ conditioning on postoperative hypothermia and SSI and to perform a cost-effectiveness analysis.

Methods

A retrospective cohort study of patients undergoing elective laparoscopic colorectal resection was performed at a single UK specialist centre. The control group (n = 123) received peritoneal insufflation with room temperature, dry CO₂, whereas the intervention group (n = 123) received warm, humidified CO₂ (using HumiGard™, Fisher & Paykel Healthcare). The outcomes were postoperative hypothermia, SSI and costs. Multivariate analysis was performed.

Results

A total of 246 patients were included in the study. The mean age was 68 (20–87) and mean BMI 28 (15–51). The primary diagnosis was cancer (n = 173), and there were no baseline differences between the groups. CO₂ conditioning significantly decreased the incidence of postoperative hypothermia (odds ratio 0.10, 95 % CI 0.04–0.23), with hypothermic patients found to be at increased risk of SSI (odds ratio 4.0, 95 % CI 1.25–12.9). Use of conditioned CO₂ significantly decreased the incidence of SSI by 66 % (p = 0.04). The intervention group incurred costs of £155 less per patient. The incremental cost-effectiveness ratio was negative.

Conclusion

CO₂ conditioning during laparoscopic colorectal surgery is a safe, feasible and a cost-effective intervention. It improves the quality of surgical care relating to SSI and postoperative hypothermia.

Efficacy of intravenous fluid warming during goal-directed fluid therapy in patients undergoing laparoscopic colorectal surgery: a randomized controlled trial

Objective

To evaluate the clinical efficacy of intravenous (IV) fluid warming in patients undergoing laparoscopic colorectal surgery.

Methods

Adult patients undergoing laparoscopic colorectal surgery were randomly assigned to receive either IV fluids at room temperature (control group) or warmed IV fluids (warm fluids group). Each patient received a standardized goal-directed fluid regimen based on stroke volume variances. Oesophageal temperature was measured at 15 min intervals for 2 h after induction of anaesthesia.

Results

A total of 52 patients were enrolled in the study. The drop in core temperature in the warm fluids group was significantly less than in the control group 2 h after the induction of anaesthesia. This significant difference was seen from 30 min after induction.

Conclusion

IV fluid warming was associated with a smaller drop in core temperature than room temperature IV fluids in laparoscopic colorectal surgery incorporating goal-directed fluid therapy.

Warmed and humidified carbon dioxide for abdominal laparoscopic surgery: meta-analysis of the current literature

BACKGROUND

The creation of a pneumoperitoneum for laparoscopic surgery is performed by the insufflation of carbon dioxide (CO₂). The insufflated CO₂ is generally at room temperature (20-25 °C) and dry (0-5 % relative humidity). However, these physical characteristics could lead to alterations of the peritoneal cavity, leading to operative and postoperative complications. Warming and humidifying the insufflated gas has been proposed to reduce the iatrogenic effects of laparoscopic surgery, such as pain, hypothermia and peritoneal alterations. Two medical devices are currently available for laparoscopic surgery with warm and humidified CO₂.

METHODS

Clinical studies were identified by searching PubMed with keywords relating to humidified and warmed CO₂ for laparoscopic procedures. Analysis of the literature focused on postoperative pain, analgesic consumption, duration of hospital stay and convalescence, surgical techniques and hypothermia.

RESULTS

Bibliographic analyses reported 114 publications from 1977 to 2015, with only 17 publications of clinical interest. The main disciplines focused on were gynaecological and digestive surgery ). Analysis of the studies selected reported only a small beneficial effect of warmed and humidified laparoscopy compared to standard laparoscopy on immediate postoperative pain and per procedure hypothermia. No difference was observed for later postoperative shoulder pain, morphine equivalent daily doses, postoperative body core temperature, recovery room and hospital length of stay, lens fogging and procedure duration.

CONCLUSIONS

Only few beneficial effects on immediate postoperative pain and core temperature have been identified in this meta-analysis. Although more studies are probably needed to close the debate on the real impact of warmed and humidified CO₂ for laparoscopic procedures.

Humidification during laparoscopic surgery: overview of the clinical benefits of using humidified gas during laparoscopic surgery

PURPOSE

The peritoneum is the serous membrane that covers the abdominal cavity and most of the intra-abdominal organs. It is a very delicate layer highly susceptible to damage and it is not designed to cope with variable conditions such as the dry and cold carbon dioxide (CO2) during laparoscopic surgery. The aim of this review was to evaluate the effects caused by insufflating dry and cold gas into the abdominal cavity after laparoscopic surgery.

METHODS

A literature search using the Pubmed was carried out. Articles identified focused on the key issues of laparoscopy, peritoneum, morphology, pneumoperitoneum, humidity, body temperature, pain, recovery time, post-operative adhesions and lens fogging.

RESULTS

Insufflating dry and cold CO2 into the abdomen causes peritoneal damage, post-operative pain, hypothermia and post-operative adhesions. Using humidified and warm gas prevents pain after surgery. With regard to hypothermia due to desiccation, it can be fully prevented using humidified and warm gas. Results relating to the patient recovery are still controversial.

CONCLUSIONS

The use of humidified and warm insufflation gas offers a significant clinical benefit to the patient, creating a more physiologic peritoneal environment and reducing the post-operative pain and hypothermia. In animal models, although humidified and warm gas reduces post-operative adhesions, humidified gas at 32 °C reduced them even more. It is clear that humidified gas should be used during laparoscopic surgery; however, a question remains unanswered: to achieve even greater clinical benefit to the patient, at what temperature should the humidified gas be when insufflated into the abdomen? More clinical trials should be performed to resolve this query.

Peritoneal Tumorigenesis and Inflammation are Ameliorated by Humidified-Warm Carbon Dioxide Insufflation in the Mouse

Background

Conventional laparoscopic surgery uses CO₂ that is dry and cold, which can damage peritoneal surfaces. It is speculated that disseminated cancer cells may adhere to such damaged peritoneum and metastasize. We hypothesized that insufflation using humidified-warm CO₂, which has been shown to reduce mesothelial damage, will also ameliorate peritoneal inflammation and tumor cell implantation compared to conventional dry-cold CO₂.

Methods

Laparoscopic insufflation was modeled in mice along with anesthesia and ventilation. Entry and exit ports were introduced to maintain insufflation using dry-cold or humidified-warm CO₂ with a constant flow and pressure for 1 h; then 1000 or 1 million fluorescent-tagged murine colorectal cancer cells (CT26) were delivered into the peritoneal cavity. The peritoneum was collected at intervals up to 10 days after the procedure to measure inflammation, mesothelial damage, and tumor burden using fluorescent detection, immunohistochemistry, and scanning electron microscopy.

Results

Rapid temperature control was achieved only in the humidified-warm group. Port-site tumors were present in all mice. At 10 days, significantly fewer tumors on the peritoneum were counted in mice insufflated with humidified-warm compared to dry-cold CO₂ (p < 0.03). The inflammatory marker COX-2 was significantly increased in the dry-cold compared to the humidified-warm cohort (p < 0.01), while VEGFA expression was suppressed only in the humidified-warm cohort. Significantly less mesothelial damage and tumor cell implantation was evident from 2 h after the procedure in the humidified-warm cohort.

Conclusions

Mesothelial cell damage and inflammation are reduced by using humidified-warm CO₂ for laparoscopic oncologic surgery and may translate to reduce patients’ risk of developing peritoneal metastasis.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-015-4508-1) contains supplementary material, which is available to authorized users.

Insufflation with humidified and heated carbon dioxide in short-term laparoscopy: a double-blinded randomized controlled trial

Background. We tested the hypothesis that warm-humidified carbon dioxide (CO₂) insufflation would reduce postoperative pain and morphine requirement compared to cold-dry CO₂ insufflation. Methods. A double-blinded, randomized, controlled trial was conducted to compare warm, humidified CO₂ and cold-dry CO₂. Patients with benign uterine diseases were randomized to either treatment (n = 48) or control (n = 49) group during laparoscopically assisted vaginal hysterectomy. Primary endpoints of the study were rest pain, movement pain, shoulder-tip pain, and cough pain at 2, 4, 6, 24, and 48 hours postoperatively, measured by visual analogue scale. Secondary outcomes were morphine consumption, rejected boli, temperature change, recovery room stay, and length of hospital stay. Results. There were no significant differences in all baseline characteristics. Shoulder-tip pain at 6 h postoperatively was significantly reduced in the intervention group. Pain at rest, movement pain, and cough pain did not differ. Total morphine consumption and rejected boli at 24 h postoperatively were significantly higher in the control group. Temperature change, recovery room stay, and length of hospital were similar. Conclusions. Warm, humidified insufflation gas significantly reduces postoperative shoulder-tip pain as well as morphine demand. This trial is registered with Clinical Trial Registration Number   DRKS00003853 (German Clinical Trials Register (DRKS)).

Treating postlaparoscopic surgery shoulder pain with acupuncture

Objective. The purpose of this study was to examine the effect of acupuncture on postlaparoscopic shoulder pain (PLSP) which is a common side effect in patients undergoing abdominal laparoscopic surgery. Methods. Patients with moderate to severe PLSP in spite of analgesic treatment, which were referred by the medical staff to the Complementary-Integrative Surgery Service (CISS) at our institution, were provided with acupuncture treatment. The severity of PLSP and of general pain was assessed using a Visual Analogue Scale (VAS) from 0 to 10. Pain assessment was conducted prior to and two hours following acupuncture treatment. Acupuncture treatment was individualized based on traditional Chinese medicine diagnosis. Results. A total of 25 patients were evaluated during a 14-month period, from March 2011 to May 2012. A significant reduction in PLSP (mean reduction of 6.4 ± 2.3 P < 0.0001) and general pain (mean reduction 6.4 ± 2.1 P < 0.0001) were observed, and no significant side effects were reported. Conclusion. Individualized acupuncture treatments according to traditional Chinese medicine principles may improve postlaparoscopic shoulder pain and general pain when used in conjunction with conventional therapy. The primary findings of this study warrant verification in controlled studies.

Evaluation of the effect of intra-operative intravenous fluid on post-operative pain and pulmonary function: a randomized trial comparing 10 and 30 ml kg(-1) of crystalloid

BACKGROUND

Existing evidence suggests that administration of intravenous fluids has been shown to improve outcomes including pain in gynecological laparoscopic surgery but the optimum fluid dose has not been determined.

AIMS

To determine the effect of administration of intravenous fluids on post-operative pain and pulmonary function after gynecological laparoscopy.

METHODS

In a prospective randomized double-blinded study 100 ASA 1 and 2 elective patients undergoing gynecological laparoscopy were randomized to receive intravenous compound sodium lactate 10 ml kg(-1) (CSL10-restrictive) or 30 ml kg(-1) (CSL30-liberal) administered intra-operatively. The primary outcome measure was the post-operative pain score at 24, 48 and 72 h, assessed by 0-10 verbal rating scale (VRS). Pulmonary function (FEV1, FVC, PEFR) and oxygen saturation were also measured.

RESULTS

Patients who received CSL 30 had lower post-operative pain scores than CSL 10 (ANCOVA-mean difference = 0.47, 95 % CI 0.11-0.83, P = 0.01). Post-operative pain VRS was lower in CSL30 than CSL10 at 48 h (mean difference 0.56, 95 % CI 0.04-1.09, P = 0.036). Patients in CSL30 reported shoulder tip pain less frequently than those in CSL10 (30.4 vs. 43.9 % of assessments, P = 0.03, OR 0.58) but reported wound pain more frequently 39.0 vs. 24.2 %, P = 0.01, OR 2.0). Indices of pulmonary function did not differ between groups at any time.

CONCLUSIONS

Liberal compared to restrictive administration of i.v. crystalloid is associated with a clinical modest reduction in pain. Pulmonary dysfunction was not increased with liberal fluid administration.

Warm, humidified carbon dioxide gas insufflation for laparoscopic appendicectomy in children: a double-blinded randomized controlled trial

OBJECTIVE

To investigate clinical benefits of warm, humidified carbon dioxide (CO(2)) insufflation for acute laparoscopic appendicectomy on postoperative pain and recovery in children (age 8-14 years).

BACKGROUND

Conventional CO(2) insufflation leads to desiccation-related peritoneal inflammation and injury, which is preventable with warm, humidified CO2 gas. We hypothesized that reduced peritoneal desiccation would improve patient-centered outcomes in children after laparoscopic appendicectomy.

METHOD

A double-blinded, randomized controlled trial was conducted. Intervention group participants received warm (37°C), humidified (98% relative humidity) CO(2) gas insufflation, whereas control participants received standard room temperature (20°C) gas with 0% relative humidity. Perioperative analgesia and anesthesia were standardized. Postoperative opiate usage was converted to morphine equivalent daily dosages (MEDD) for comparison, and pain intensity at rest and on moving was rated by participants using visual analog scales. Postoperative recovery and return to normal activities was assessed using a questionnaire on day 10.

RESULTS

Between February 2010 and March 2011, a total of 190 participants were randomized. Both intervention and control groups were matched at baseline. Postoperative MEDD and pain scores were also similar. There were no differences in postoperative recovery parameters.

CONCLUSIONS

Warm, humidified CO(2) insufflation for acute laparoscopic appendicectomy has no short-term clinical benefits on postoperative outcomes in pediatric patients (ClinicalTrials.gov trial identifying code: NCT01027455).

Prevention of vessel desiccation and maintenance of normal morphology during endovascular harvesting using humidified warmed gas

Dry, cold CO₂ gas was found to cause tissue damage during endovascular harvest. The use of warmed, humidified CO₂ gas appeared to maintain vessel morphology and integrity during endovascular harvest by preventing tissue desiccation.

Background and Objectives:

Endoscopic vessel harvesting (EVH) traditionally uses carbon dioxide (CO₂) gas for insufflation. The CO₂ based on government regulations is bone dry and room temperature. All previous EVH studies use this type of unconditioned gas. It is hypothesized that by changing the quality of CO₂ gas differences may occur that are attributable to dry gas versus wet gas exposure.

Methods:

A comparison of the effect(s) of traditional dry CO₂ gas compared to humidified exposure was done using a porcine model and evaluated in a double-blind randomized controlled fashion.

Results:

Vessels exposed to traditional dry cold gas had morphologic and structural changes noted on histologic evaluation. This included desiccation changes of the tunica adventitia desiccation and tunica media collagen and elastin. Vessels exposed to dry gas showed 10% to 12% contraction and constriction with tortuous changes to the intima and endothelial lining that were progressive with increasing volumes of gas exposure. No desiccation or morphologic changes were seen with humidified warmed gas produced using the VesselGuardian.

Conclusions:

Traditional dry cold CO₂ caused vascular tissue damage extending from the adventitia to intima, changing the vessel in morphologic and structural configuration. With the VesselGuardian humidified warmed, gas maintained vessel morphology and integrity by preventing desiccation. Changing the quality of CO₂ from dry and cold to wet and warm may offer clinical utility for a better quality conduit for coronary artery bypass graft procedures.

Shakespeare's view of the laparoscopic pneumoperitoneum

Shakespeare's premonition regarding chilling effects and intentionally induced unhappy events perpetrated on the peritoneal cavity is not, nor cannot, come to good.

Background:

The laparoscopic pneumoperitoneum is created and maintained in a physiologically homeostatic potential space that is 37-degrees Centigrade (^oC) and covered by a wet film of peritoneal fluid. The currently used gas is carbon dioxide that is instilled at 21^oC and extremely dry. Altering this privileged space is a violation of surgical safety, principles, and reason. Maintaining normal healthy conditions in their original state by humidifying and warming the gas eliminates the rub of dry gas and takes arms against a sea of troubles.

Database:

Literature search using PubMed and Cochrane databases identifying articles focusing on laparoscopy, pneumoperitoneum, hypothermia, evaporation, desiccation, peritoneum, and morphology.

Conclusions:

Shakespeare's premonitions regarding the chilling effects and intentionally induced unhappy events perpetrated on the peritoneal cavity is not nor cannot come to good. The absence of water in the gas going into a wetted cavity causes perilous circumstances, resulting in evaporative hypothermia, tissue desiccation, and damage that precede adhesion formation. Providing the most protective canopy for the intraabdominal cavity with humidity and warmth prevents calamitous clinical outcomes and mirrors nature's intent. The virtue is in doing no harm.

Heated CO(2) with or without humidification for minimally invasive abdominal surgery

BACKGROUND

Intraoperative hypothermia during both open and laparoscopic abdominal surgery may be associated with adverse events. For laparoscopic abdominal surgery, the use of heated insufflation systems for establishing pneumoperitoneum has been described to prevent hypothermia. Humidification of the insufflated gas is also possible. Past studies have shown inconclusive results with regards to maintenance of core temperature and reduction of postoperative pain and recovery times.

OBJECTIVES

To determine the effect of heated gas insufflation on patient outcomes following minimally invasive abdominal surgery.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library), MEDLINE (PubMed), EMBASE, International Pharmaceutical Abstracts (IPA), Web of Science, Scopus, www.clinicaltrials.gov and the National Research Register were searched (1956 to 14 June 2010). Grey literature and cross-references were also searched. Searches were limited to human studies without language restriction.

SELECTION CRITERIA

All included studies were randomized trials comparing heated (with or without humidification) gas insufflation with cold gas insufflation in adult and pediatric populations undergoing minimally invasive abdominal procedures. Study quality was assessed in regards to relevance, design, sequence generation, allocation concealment, blinding, possibility of incomplete data and selective reporting. The selection of studies for the review was done independently by two authors, with any disagreement resolved in consensus with a third co-author.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, data extraction and methodological quality assessment of the trials were performed by the authors. Data from eligible studies were collected using data sheets. Results were presented using mean differences for continuous outcomes and relative risks with 95% confidence intervals for dichotomous outcomes. The estimated effects were calculated using the latest version of RevMan software. Publication bias was taken into consideration and funnel plots were compiled.

MAIN RESULTS

Sixteen studies were included in the analysis. During laparoscopic abdominal surgery, no effect on postoperative pain nor changes in core temperature, morphine consumption, length of hospitalisation, lens fogging, length of operation or recovery room stay were associated with heated compared to cold gas insufflation with or without humidification.

AUTHORS' CONCLUSIONS

The study offers evidence that during laparoscopic abdominal surgery, heated gas insufflation, with or without humidification, has minimal benefit on patient outcomes.

Laparoscopic lens fogging: a review of etiology and methods to maintain a clear visual field

Laparoscopic surgical procedures are becoming common across surgical specialties, including urology. Maintaining a clear field of vision is paramount in such procedures not only for safety by preventing inadvertent injury, but also to improve precision and reduce operative time. Laparoscopic lens fogging (LLF) is a major impediment to a clear visual field during laparoscopy and is caused by condensation as well as particulate debris, blood, and smoke accumulation on the scope lens. Despite many available techniques to improve vision during laparoscopy, available data on etiology and methods to improve vision have only sporadically been considered in the literature. The objective of this review was to summarize current literature on the etiology of LLF and other causes of poor vision during laparoscopy and also review the current approaches for minimizing or reducing such events. In summary, although the etiology of LLF is well understood, that is, temperature and humidity differences, the methods to reduce its occurrence lack significant data. Of those methods that are often espoused, most are not supported in the literature, such as warmed and humidified insufflation gas, or simply lack data, such as antifogging solutions.