Heated insufflation with or without humidification for laparoscopic abdominal surgery

Estimation of the difference between peritoneal microenvironment and core body temperature during laparoscopic surgery - a prospective observational study

Maintaining patients' temperature during surgery is beneficial since hypothermia has been linked with perioperative complications. Laparoscopic surgery involves the insufflation of carbon dioxide (CO2) into the peritoneal cavity and has become the standard in many surgical indications since it is associated with better and faster recovery. However, the use of cold and dry CO2 insufflation can lead to perioperative hypothermia. We aimed to assess the difference between intraperitoneal and core temperatures during laparoscopic surgery and evaluate the influence of duration and CO2 insufflation volume by fitting a mixed generalized additive model. In this prospective observational single-center cohort trial, we included patients aged over 17 with American Society of Anesthesiology risk scores I to III undergoing laparoscopic surgery. Anesthesia, ventilation, and analgesia followed standard protocols, while patients received active warming using blankets and warmed fluids. Temperature data, CO2 ventilation parameters, and intraabdominal pressure were collected. We recruited 51 patients. The core temperature was maintained above 36 °C and progressively raised toward 37 °C as pneumoperitoneum time passed. In contrast, the intraperitoneal temperature decreased, thus creating a widening difference from 0.4 [25th-75th percentile: 0.2-0.8] °C at the beginning to 2.3 [2.1-2.3] °C after 240 min. Pneumoperitoneum duration and CO2 insufflation volume significantly increased this temperature difference (P < 0.001 for both parameters). Core vs. intraperitoneal temperature difference increased linearly by 0.01 T °C per minute of pneumoperitoneum time up to 120 min and then 0.05 T °C per minute. Each insufflated liter per unit of time, i.e. every 10 min, increased the temperature difference by approximately 0.009 T °C. Our findings highlight the impact of pneumoperitoneum duration and CO2 insufflation volume on the difference between core and intraperitoneal temperatures. Implementing adequate external warming during laparoscopic surgery effectively maintains core temperature despite the use of dry and unwarmed CO2 gases, but peritoneal hypothermia remains a concern, suggesting the importance of further research into regional effects.Trial registration: Clinicaltrials.gov: NCT04294758.

Application value of machine learning models in predicting intraoperative hypothermia in laparoscopic surgery for polytrauma patients

BACKGROUND

Hypothermia during laparoscopic surgery in patients with multiple trauma is a significant concern owing to its potential complications. Machine learning models offer a promising approach to predict the occurrence of intraoperative hypothermia.

AIM

To investigate the value of machine learning model to predict hypothermia during laparoscopic surgery in patients with multiple trauma.

METHODS

This retrospective study enrolled 220 patients who were admitted with multiple injuries between June 2018 and December 2023. Of these, 154 patients were allocated to a training set and the remaining 66 were allocated to a validation set in a 7:3 ratio. In the training set, 53 cases experienced intraoperative hypothermia and 101 did not. Logistic regression analysis was used to construct a predictive model of intraoperative hypothermia in patients with polytrauma undergoing laparoscopic surgery. The area under the curve (AUC), sensitivity, and specificity were calculated.

RESULTS

Comparison of the hypothermia and non-hypothermia groups found significant differences in sex, age, baseline temperature, intraoperative temperature, duration of anesthesia, duration of surgery, intraoperative fluid infusion, crystalloid infusion, colloid infusion, and pneumoperitoneum volume (P < 0.05). Differences between other characteristics were not significant (P > 0.05). The results of the logistic regression analysis showed that age, baseline temperature, intraoperative temperature, duration of anesthesia, and duration of surgery were independent influencing factors for intraoperative hypothermia during laparoscopic surgery (P < 0.05). Calibration curve analysis showed good consistency between the predicted occurrence of intraoperative hypothermia and the actual occurrence (P > 0.05). The predictive model had AUCs of 0.850 and 0.829 for the training and validation sets, respectively.

CONCLUSION

Machine learning effectively predicted intraoperative hypothermia in polytrauma patients undergoing laparoscopic surgery, which improved surgical safety and patient recovery.

The role of warmed-humidified carbon dioxide insufflation in colorectal surgery: A systematic review and meta-analysis

BACKGROUND

Maintenance of normothermia is a crucial part of enhanced recovery after colorectal surgery. Dry-cold carbon dioxide (CO2 ) traditionally used for insufflation in laparoscopic surgery and negative pressure operating theatres has been associated with intraoperative hypothermia. Studies suggest that use of warmed-humidified CO2 may promote normothermia. However, due to a scarcity of high-quality studies demonstrating a proven benefit on intraoperative core body temperature, its use in colorectal surgery remains limited. Therefore, the aim of this review was to evaluate the effects of warmed-humidified CO2 compared to traditional dry-cold CO2 , or ambient air in operating theatres, during colorectal surgery.

METHODS

A search of Medline, EMBASE, and CENTRAL was performed. Randomised controlled trials (RCTs) that compared patients receiving warmed-humidified CO2 with either dry-cold CO2 insufflation in laparoscopic procedures or no insufflation during open surgery were included. The primary outcome was change in intraoperative core body temperature. Secondary outcomes included length of stay, operating time, return of gastrointestinal function, wound infection, and postoperative pain. A pairwise meta-analysis was performed using inverse variance random effects.

RESULTS

Among the six RCTs included, 208 patients received warmed-humidified CO2 (42.3% female, mean age: 65.8 years) and 210 patients received either dry-cold CO2 in laparoscopic procedures or no gas insufflation during open procedures (46.2% female, mean age: 66.1 years). No significant difference was found for change in intraoperative core body temperature (MD = 0.01, 95% CI: -0.1, 0.11, p = 0.90, very low certainty). Patients in the warmed-humidified CO2 group had significantly higher pain scores on postoperative day 1 (MD = 1.61, 95% CI: 0.91, 2.31, p < 0.05, very low certainty). No significant differences were found in any of the other secondary outcomes studied.

CONCLUSION

Patients undergoing colorectal surgery receiving warmed-humidified CO2 do not experience any clinically meaningful difference in core body temperature change compared to their counterparts receiving dry-cold CO2 insufflation or no insufflation. However, patients may report greater pain scores on postoperative day 1 with warmed-humidified CO2 . There is likely no clinically important difference between warmed-humidified CO2 and dry-cold CO2 for patients undergoing colorectal surgery. Patient, clinician, and institution factors should be considered when deciding between these two insufflation modalities.

Guidelines for Perioperative Care for Liver Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations 2022

BACKGROUND

Enhanced Recovery After Surgery (ERAS) has been widely applied in liver surgery since the publication of the first ERAS guidelines in 2016. The aim of the present article was to update the ERAS guidelines in liver surgery using a modified Delphi method based on a systematic review of the literature.

METHODS

A systematic literature review was performed using MEDLINE/PubMed, Embase, and the Cochrane Library. A modified Delphi method including 15 international experts was used. Consensus was judged to be reached when >80% of the experts agreed on the recommended items. Recommendations were based on the Grading of Recommendations, Assessment, Development and Evaluations system.

RESULTS

A total of 7541 manuscripts were screened, and 240 articles were finally included. Twenty-five recommendation items were elaborated. All of them obtained consensus (>80% agreement) after 3 Delphi rounds. Nine items (36%) had a high level of evidence and 16 (64%) a strong recommendation grade. Compared to the first ERAS guidelines published, 3 novel items were introduced: prehabilitation in high-risk patients, preoperative biliary drainage in cholestatic liver, and preoperative smoking and alcohol cessation at least 4 weeks before hepatectomy.

CONCLUSIONS

These guidelines based on the best available evidence allow standardization of the perioperative management of patients undergoing liver surgery. Specific studies on hepatectomy in cirrhotic patients following an ERAS program are still needed.

Low Intra-Abdominal Pressure with Complete Neuromuscular Blockage Reduces Post-Operative Complications in Major Laparoscopic Urologic Surgery: A before-after Study

Most urological interventions are now performed with minimally invasive surgery techniques such as laparoscopic surgery. Combining ERAS protocols with minimally invasive surgery techniques may be the best option to reduce hospital length-of-stay and post-operative complications. We designed this study to test the hypothesis that using low intra-abdominal pressures (IAP) during laparoscopy may reduce post-operative complications, especially those related to reduced intra-operative splanchnic perfusion or increased splanchnic congestion. We applied a complete neuromuscular blockade (NMB) to maintain an optimal space and surgical view. We compared 115 patients treated with standard IAP and moderate NMB with 148 patients treated with low IAP and complete NMB undergoing major urologic surgery. Low IAP in combination with complete NMB was associated with fewer total post-operative complications than standard IAP with moderate NMB (22.3% vs. 41.2%, p < 0.001), with a reduction in all medical post-operative complications (17 vs. 34, p < 0.001). The post-operative complications mostly reduced were acute kidney injury (15.5% vs. 30.4%, p = 0.004), anemia (6.8% vs. 16.5%, p = 0.049) and reoperation (2% vs. 7.8%, p = 0.035). The intra-operative management of laparoscopic interventions for major urologic surgeries with low IAP and complete NMB is feasible without hindering surgical conditions and might reduce most medical post-operative complications.

Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery

BACKGROUND

This is the second update of a Cochrane Review first published in 2013 and last updated in 2017. Laparoscopic surgery is now widely performed to treat various abdominal diseases. Currently, carbon dioxide is the most frequently used gas for insufflation of the abdominal cavity (pneumoperitoneum). Although carbon dioxide meets most of the requirements for pneumoperitoneum, the absorption of carbon dioxide may be associated with adverse events. Therefore, other gases have been introduced as alternatives to carbon dioxide for establishing pneumoperitoneum.

OBJECTIVES

To assess the safety, benefits, and harms of different gases (e.g. carbon dioxide, helium, argon, nitrogen, nitrous oxide, and room air) used for establishing pneumoperitoneum in participants undergoing laparoscopic abdominal or gynaecological pelvic surgery.

SEARCH METHODS

We searched CENTRAL, Ovid MEDLINE, Ovid Embase, four other databases, and three trials registers on 15 October 2021 together with reference checking, citation searching, and contact with study authors to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different gases for establishing pneumoperitoneum in participants (irrespective of age, sex, or race) undergoing laparoscopic abdominal or gynaecological pelvic surgery under general anaesthesia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included 10 RCTs, randomising 583 participants, comparing different gases for establishing pneumoperitoneum: nitrous oxide (four trials), helium (five trials), or room air (one trial) was compared to carbon dioxide. All the RCTs were single-centre studies. Four RCTs were conducted in the USA; two in Australia; one in China; one in Finland; one in Iran; and one in the Netherlands. The mean age of the participants ranged from 27.6 years to 49.0 years. Four trials randomised participants to nitrous oxide pneumoperitoneum (132 participants) or carbon dioxide pneumoperitoneum (128 participants). None of the trials was at low risk of bias. The evidence is very uncertain about the effects of nitrous oxide pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto odds ratio (OR) 2.62, 95% CI 0.78 to 8.85; 3 studies, 204 participants; very low-certainty evidence), or surgical morbidity (Peto OR 1.01, 95% CI 0.14 to 7.31; 3 studies, 207 participants; very low-certainty evidence). There were no serious adverse events related to either nitrous oxide or carbon dioxide pneumoperitoneum (4 studies, 260 participants; very low-certainty evidence). Four trials randomised participants to helium pneumoperitoneum (69 participants) or carbon dioxide pneumoperitoneum (75 participants) and one trial involving 33 participants did not state the number of participants in each group. None of the trials was at low risk of bias. The evidence is very uncertain about the effects of helium pneumoperitoneum compared to carbon dioxide pneumoperitoneum on cardiopulmonary complications (Peto OR 1.66, 95% CI 0.28 to 9.72; 3 studies, 128 participants; very low-certainty evidence), or surgical morbidity (5 studies, 177 participants; very low-certainty evidence). There were three serious adverse events (subcutaneous emphysema) related to helium pneumoperitoneum (3 studies, 128 participants; very low-certainty evidence). One trial randomised participants to room air pneumoperitoneum (70 participants) or carbon dioxide pneumoperitoneum (76 participants). The trial was at high risk of bias. There were no cardiopulmonary complications, serious adverse events, or deaths observed related to either room air or carbon dioxide pneumoperitoneum.    AUTHORS' CONCLUSIONS: The evidence is very uncertain about the effects of nitrous oxide, helium, and room air pneumoperitoneum compared to carbon dioxide pneumoperitoneum on any of the primary outcomes, including cardiopulmonary complications, surgical morbidity, and serious adverse events. The safety of nitrous oxide, helium, and room air pneumoperitoneum has yet to be established, especially in people with high anaesthetic risk.

The effect of warm and humidified gas insufflation in gynecological laparoscopy on maintenance of body temperature: a prospective randomized controlled multi-arm trial

Background

Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patient’s temperature will fall by 1 – 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. Using warm and humidified gas insufflation in laparoscopy may help in the maintenance of intraoperative body temperature.

Methods

In this prospective randomized controlled study, we investigated effects of temperature and humidity of the insufflation gas on intra- and postoperative temperature management. 150 patients undergoing gynecologic laparoscopic surgery were randomly assigned to either insufflation with non-warmed, non-humidified CO₂ with forced air warming blanket (AIR), humidified warm gas without forced air warming blanket (HUMI) or humidified warm gas combined with forced air warming blanket (HUMI+). We hypothesized that the use of warmed laparoscopic gas would have benefits in the maintenance of body temperature and reduce the occurrence of hypothermia.

Results

The use of warm and humidified gas insufflation alone led to more hypothermia episodes with longer duration and longer recovery times as well as significantly lower core body temperature compared to the other two groups. In the comparison of the AIR group and HUMI + group, HUMI + patients had a significantly higher body temperature at arrival at the PACU (Post Anaesthesia Care Unit), had the least occurrence of hypothermia and suffered from less shivering.

Conclusion

The use of warm and humidified gas insufflation alone does not sufficiently warm the patients. The optimal temperature management is achieved in the combination of external forced air warming and insufflation of warm and humidified laparoscopy gas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-022-06499-z.

Establishment and obstacle analysis of evidence-based nursing indexes for unplanned hypothermia management in patients undergoing laparoscopic operation

BACKGROUND

This study sought to implement evidence-based nursing practices for patients undergoing laparoscopy surgery to prevent unplanned hypothermia, to develop review indicators for evidence-based nursing practices, and to analyze obstacles and contributing factors.

METHODS

Using the Joanna Briggs Institute health care model as the evidence-based theoretical framework, clinical problems were identified, evidence was systematically researched, evaluated and summarized, an index and method of examination was established, and quality items were examined. According to the results of the baseline review, the obstacles and promoting factors were analyzed, and methods and countermeasures were developed.

RESULTS

This study summarized 15 pieces of best evidence in relation to the following 5 aspects: risk assessment, body temperature monitoring, ambient temperature, passive insulation, and active insulation. There were 11 quality review indicators, only 4 of which had compliance rates of 100%. The main obstacle factors were a lack of nursing norms and operating procedures, a lack of information, and a lack of motivation among nursing staff.

CONCLUSIONS

Based on the best evidence and the professional judgment of clinical staff, the quality review index is scientific and implementable. In the application of this clinical evidence, obstacles and other factors should be solved to promote the transformation of evidence.

Warm and humidified insufflation gas during gynecologic laparoscopic surgery reduces postoperative pain in predisposed patients-a randomized, controlled multi-arm trial

BACKGROUND

Postoperative pain remains a common problem in gynecologic laparoscopy, especially in head zone-related regions, triggered by intra-abdominal pressure during capnoperitoneum. Humidified and prewarmed insufflation gas may ameliorate pain and be beneficial.

METHODS

This prospective randomized controlled parallel group multi-arm single-center study investigated the effects of temperature and humidity of insufflation gas on postoperative pain during gynecologic laparoscopy with a duration ≥ 60 min. Female participants (18-70 years) were blinded and randomly assigned-computer generated-to either insufflation with dry cold CO₂ with forced air warming blanket ("AIR"), humidified warm gas without forced air warming blanket ("HUMI"), or humidified warm gas with forced air warming blanket ("HUMI +"). We hypothesized that using humidified warm gas resulted in lower pain scores and less analgesic consumption. The primary endpoint postoperative pain was assessed for different pain localizations every 12 h during 7 days after surgery. Secondary endpoints were demand for painkillers and epidural anesthetics, length of stay in recovery room, and hospital stay. (Registration: ClinicalTrials.gov NCT02781194-completed).

RESULTS

150 participants were randomized. Compared to group "AIR" (n = 48), there was significantly less pain in group "HUMI +" (n = 48) in the recovery room (- 1.068; 95% CI - 2.08 to - 0.061), as well as significantly less ibuprofen use at day two (- 0.5871 g ± 0.258; p-value = 0.0471). Other variables did not change significantly. Stratification for presence of endometriosis or non-previous abdominal surgery in patient history revealed significantly less pain in both groups "HUMI" (n = 50) and "HUMI +" versus group "AIR." Related side effects were not noted.

CONCLUSION

In the overall population, the use of warm, humidified insufflation gas did not yield clinically relevant effects; however, in predisposed patients with endometriosis and who could otherwise expect high pain levels, warm and humidified gas may be beneficial.

Summary of the best evidence for the prevention of intraoperative unplanned hypothermia in patients undergoing laparoscopic surgery

Background

This study aimed to search, analyze, and summarize relevant evidence for the prevention of unplanned hypothermia in patients undergoing laparoscopic surgery, so as to reduce the incidence of unplanned hypothermia in patients undergoing laparoscopic surgery and provide a reference for clinical medical staff.

Methods

According to the evidence pyramid model, relevant literature were retrieved by computer in databases. Literature quality evaluation and the evidence grading system of the Australian JBI Evidence-Based Health Care Centre Evidence Recommendation Rating System were used to evaluate the literature quality and determine the level of evidence. The time limit for retrieval was from the establishment of the databases to March 31, 2021.

Results

A total of 12 studies were included in this study. Of these, 5 evidence items were finally extracted, and 15 pieces of best evidence were summarized, including the risk assessment of hypothermia in patients undergoing laparoscopic surgery, temperature monitoring, ambient temperature, passive insulation measures, and active insulation measures.

Conclusions

The evidence for the prevention of unplanned hypothermia in patients undergoing laparoscopic surgery provided evidence-based approaches for reducing the incidence of intraoperative hypothermia for clinical staffs. It is suggested that the cultural characteristics of China, medical resources, and patients' own conditions should be considered when applying the evidence.

Risk factors for inadvertent intraoperative hypothermia in patients undergoing laparoscopic surgery: A prospective cohort study

Background

Inadvertent intraoperative hypothermia is frequent during open surgeries; however, few studies on hypothermia during laparoscopic abdominal surgery have been reported. We aimed to investigate the incidence and risk factors for hypothermia in patients undergoing laparoscopic abdominal surgery.

Methods

This single-center prospective cohort observational study involved patients undergoing laparoscopic surgery between October 2018 and June 2019. Data on core body temperature and potential variables were collected. A multivariate logistic regression analysis was performed to identify the risk factors associated with hypothermia. A Cox regression analysis was used to verify the sensitivity of the results.

Results

In total, 690 patients were included in the analysis, of whom 200 (29.0%, 95% CI: 26%−32%) had a core temperature < 36°C. The core temperature decreased over time, and the incident hypothermia increased gradually. In the multivariate logistic regression analysis, age (OR = 1.017, 95% CI: 1.000–1.034, P = 0.050), BMI (OR = 0.938, 95% CI: 0.880–1.000; P = 0.049), baseline body temperature (OR = 0.025, 95% CI: 0.010–0.060; P < 0.001), volume of irrigation fluids (OR = 1.001, 95% CI: 1.000–1.001, P = 0.001), volume of urine (OR = 1.001, 95% CI: 1.000–1.003, P = 0.070), and duration of surgery (OR = 1.010, 95% CI: 1.006–1.015, P < 0.001) were significantly associated with hypothermia. In the Cox analysis, variables in the final model were age, BMI, baseline body temperature, volume of irrigation fluids, blood loss, and duration of surgery.

Conclusions

Inadvertent intraoperative hypothermia is evident in patients undergoing laparoscopic surgeries. Age, BMI, baseline body temperature, volume of irrigation fluids, and duration of surgery are significantly associated with intraoperative hypothermia.

Does the Laminar Airflow System Affect the Development of Perioperative Hypothermia? A Randomized Clinical Trial

OBJECTIVES

We aimed to compare tympanic membrane temperature changes and the incidence of inadvertent perioperative hypothermia (IPH) in patients undergoing laparoscopic cholecystectomy under general anesthesia in laminar airflow systems (LAS-OR) and conventional turbulent airflow systems (CAS-OR).

BACKGROUND

Different heating, ventilation, and air-conditioning (HVAC) systems are used in the operating room (OR), such as LAS and CAS. Laminar airflow is directed directly to the patient in LAS-OR. Does laminar airflow in ORs cause faster heat loss by convection?

METHODS

This is a prospective, randomized study. We divided 200 patients with simple randomization (1:1), as group LAS and group CAS, and took the patients into the LAS-OR or CAS-OR for the operation. Clinical trial number: IRCT20180324039145N3. The tympanic membrane temperatures of patients were measured (°C) before anesthesia induction (T ₀) and then every 15 min during surgery (T_n). Changes (Δ_n) between T ₀ and T_n were measured.

RESULTS

In the first 30 min, there was a temperature decrease of approximately 0.8 °C (1.44 °F) in both groups. Temperature decreases at 45 min were higher in group LAS than in group CAS but not statistically significant, Δ₄₅, respectively, 0.89 (95% confidence interval [CI] [0.77, 1.02]) versus 0.77 (95% CI [0.69, 0.84]; p = .09). IPH occurred in a total of 60.9% (112 of 184) of patients in the entire surgical evaluation period in group LAS and group CAS (58.9% vs. 62.8%, p = . 59).

CONCLUSIONS

IPH is seen frequently in both HVAC systems. Clinically, the advantage of HVAC systems relative to each other has not been demonstrated during laparoscopic cholecystectomy.

Effects of Warmed and Humidified CO2 Surgical Site Insufflation in a Novel Experimental Model of Magnetic Compression Colonic Anastomosis

Background. Pneumoperitoneum insufflation with warmed and humidified carbon dioxide (WH-CO2) can prevent heat loss and increase tissue oxygenation. We evaluated the impact of localized WH-CO2 insufflation on the anastomotic healing process. Methods. Sixty male Wistar rats were randomized: Group 1 (control, n = 12), Group 2 (cold and dry CO2, CD-CO2, n = 24), and Group 3 (WH-CO2, n = 24). A magnetic compression side-to-side colonic anastomosis was performed under 60-minute local abdominal CO2 flow insufflation. Animal temperature was recorded. IL-1, IL-6, and CRP levels were assessed before and after insufflation and on postoperative day (POD) 7 and POD 10. Endoscopic follow-up was performed on POD 7 and POD 10. A burst pressure (BP) test of the specimen was performed on POD 10, and histopathological analysis was then performed. Metabolomics of the anastomotic site was determined. Results. Seven rats (5 CD-CO2 group, 1 WH-CO2 group, and 1 control group) died during the survival period. Necropsies revealed intestinal occlusions (n = 2). One additional rat from the CD-CO2 group was sacrificed on POD 7 due to intestinal perforation. The postoperative course was uneventful in the remaining cases. There was no difference in BP among the groups. Thermal monitoring confirmed that WH-CO2 insufflation was effective to reduce heat loss. IL-1 levels were statistically and significantly lower on POD 10 in the WH-CO2 group than the CD-CO2 group but not lower than the control group. CRP levels, histopathology, and metabolomics did not show any difference between the 3 groups. Conclusions. WH-CO2 was effective to preserve core temperature. However, it did not improve anastomotic healing.

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.

Pneumoperitoneum in Veterinary Laparoscopy: A Review

Objective: To review the effects of carbon dioxide pneumoperitoneum during laparoscopy, evaluate alternative techniques to establishing a working space and compare this to current recommendations in veterinary surgery. Study Design: Literature review. Sample Population: 92 peer-reviewed articles. Methods: An electronic database search identified human and veterinary literature on the effects of pneumoperitoneum (carbon dioxide insufflation for laparoscopy) and alternatives with a focus on adaptation to the veterinary field. Results: Laparoscopy is the preferred surgical approach for many human and several veterinary procedures due to the lower morbidity associated with minimally invasive surgery, compared to laparotomy. The establishment of a pneumoperitoneum with a gas most commonly facilitates a working space. Carbon dioxide is the preferred gas for insufflation as it is inert, inexpensive, noncombustible, colorless, excreted by the lungs and highly soluble in water. Detrimental side effects such as acidosis, hypercapnia, reduction in cardiac output, decreased pulmonary compliance, hypothermia and post-operative pain have been associated with a pneumoperitoneum established with CO2 insufflation. As such alternatives have been suggested such as helium, nitrous oxide, warmed and humidified carbon dioxide and gasless laparoscopy. None of these alternatives have found a consistent benefit over standard carbon dioxide insufflation. Conclusions: The physiologic alterations seen with CO2 insufflation at the current recommended intra-abdominal pressures are mild and of transient duration. Clinical Significance: The current recommendations in veterinary laparoscopy for a pneumoperitoneum using carbon dioxide appear to be safe and effective.

Can a simple 'cost-awareness' campaign for laparoscopic hysterectomy change the use and costs of disposable surgical supplies? Pre-post non-controlled study

OBJECTIVES

Does a cost-awareness campaign for gynaecologists lead to a change in use and costs of disposable surgical supplies for laparoscopic hysterectomy (LH) without increasing hospital utilisation measures (operating room (OR) time or hospital length of stay (LOS))?

DESIGN

Pre-post non-controlled study. The OR database was used to identify relevant cases before and after the cost-awareness intervention, and provided information on quantity of each supply item, operative details and LOS.

SETTING

Lois Hole Hospital for Women, Edmonton, Alberta, Canada.

PARTICIPANTS

12 laparoscopic trained gynaecologists (7 female, 5 male) participated in both phases of the study. Eligible surgical cases were all LH cases for any indication for women aged ≥18 years. 201 cases were undertaken before the intervention (2011-2013) and 229 cases after the intervention (2016-2017).

INTERVENTION

The cost-awareness intervention for gynaecologists included site meetings and rounds providing information on costs of disposable and reusable instruments, a full day skills lab, OR posters about cost and effectiveness of disposable and reusable surgical supplies and demonstrations of reusable equipment (2015-2016).

PRIMARY OUTCOME MEASURE

Disposable supplies costs per case (standardised for 2016 unit costs).

RESULTS

There was a significant (p<0.05) reduction (unadjusted) in disposable supplies cost per case for LH between cases before and after the intervention: from $C1073, SD 281, to $C943 SD 209. Regression analysis found that the adjusted cost per case after the intervention was $C116 lower than before the intervention (95% CI -160 to -71). Neither OR time nor hospital LOS differed significantly between cohorts.

CONCLUSIONS

Our study suggests that cost-awareness campaigns may be associated with reduction in the cost of surgery for LH. However, many other factors may have contributed to this cost reduction, possibly including other local initiatives to reduce costs and emerging evidence indicating lack of effectiveness of some surgical practices.

Prevention of Intraoperative Hypothermia in Laparoscopy by the Use of Body-Temperature and Humidified CO 2 : a Pilot Study

Introduction Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patient's temperature will fall by 1 - 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. The temperature of the insufflation gas is usually disregarded in the treatment and prevention of hypothermia. This study was conducted to investigate the effect of body-temperature and humidified CO ₂ on the intraoperative temperature profile and avoidance of hypothermia in laparoscopic surgery. Material and Methods In this retrospective, non-randomised case control study, 110 patients whose planned operation lasted at least 60 minutes were identified from 376 patients by means of an algorithm. Dry (20% humidity) CO ₂ at room temperature was insufflated in 51 patients (control group). 59 patients were insufflated with humidified (98% humidity) CO ₂ at body temperature (37 °C) (study group). These conditions were achieved with the HumiGard MR860 Surgical Humidification System (Fisher & Paykel Healthcare Limited, Auckland, New Zealand). The intraoperative temperature profile was evaluated by measurements every 10 minutes. Statistical analysis was performed with IBM ^® SPSS ^® Statistics 23.0.0. Results The intraoperative temperature in the control group fell steadily, while a continuous rise in temperature was observed in the study group. Warming was demonstrated in the study group with a start-end temperature difference of 0.09 °C, which differed significantly from the control group, in which it was - 0.09 °C (p = 0.011). The middle-end difference of 0.11 °C showed even higher significance in favour of the warmed gas (p = 0.003). The rate of hypothermia at the start of the operation fell from 50 to 36% in the study group and increased from 36 to 42% in the control group. Conclusion These results show that the use of body-temperature and humidified insufflation gas for laparoscopy can help to prevent intraoperative hypothermia.

Optimising Surgical Technique in Laparoscopic Cholecystectomy: a Review of Intraoperative Interventions

BACKGROUND

Laparoscopic cholecystectomy (LC) is one of the most commonly performed procedures worldwide but there is considerable variance amongst surgeons regarding intraoperative technique. This review aims to provide a comprehensive summary, with evidence-based recommendations, of intraoperative interventions in LC.

METHODS

A literature search was performed using PubMed, EMBASE, Google Scholar and Cochrane Review databases. Articles were screened for eligibility with inclusion criteria based on study design, surgical approach, surgical timing, pathology and intervention type. The most contemporary, comprehensive or relevant articles were used as the primary evidence for the final analysis and discussion.

RESULTS

A total of 25 systematic reviews and/or meta-analyses and 19 individual trials were identified from the literature and grouped into ten clinical intervention topics. Three intraoperative interventions offer clinical benefit and are recommended: wound/intraperitoneal local anaesthetic, low-pressure pneumoperitoneum and manoeuvres to reduce residual pneumoperitoneum. No benefit was demonstrated for routine subhepatic drain placement and gallbladder aspiration. Techniques which appear to demonstrate improvements but do not translate into clinical efficacy are the use of warmed/humidified carbon dioxide, installation of intraperitoneal saline and the use of advanced imaging techniques. Techniques demonstrating equipoise, and for which no recommendations can be made, are type of energy source and cystic duct occlusion methods.

DISCUSSION

This review highlights and suggests specific intraoperative techniques during uncomplicated LC that should be employed, avoided or considered by the individual surgeon. Optimising surgical technique in this way can lead to improved patient outcomes.

Canadian consensus statement: enhanced recovery after surgery in bariatric surgery

BACKGROUND

In Canada, bariatric surgery continues to remain the most effective treatment for severe obesity and its comorbidities. As the number of bariatric surgeries continues to grow, the need for consensus guidelines for optimal perioperative care is imperative. In colorectal surgery, enhanced recovery after surgery (ERAS) protocols were created for this purpose. The objective of this review is to develop evidence-based ERAS guidelines for bariatric surgery.

METHODS

A literature search of the MEDLINE database was performed using ERAS-specific search terms. Recently published articles with a focus on randomized controlled trials, systematic reviews, and meta-analyses were included. Quality of evidence and recommendations were evaluated using the GRADE assessment system.

RESULTS

Canadian bariatric surgeons from six provinces and ten bariatric centers performed a review of the evidence surrounding ERAS in bariatric surgery and created consensus guidelines for 14 essential ERAS elements. Our main recommendations were (1) to encourage participation in a presurgical weight loss program; (2) to abstain from tobacco and excessive alcohol; (3) low-calorie liquid diet for at least 2 weeks prior to surgery; (4) to avoid preanesthetic anxiolytics and long-acting opioids; (5) unfractionated or low-molecular-weight heparin prior to surgery; (6) antibiotic prophylaxis with cefazolin ± metronidazole; (7) reduced opioids during surgery; (8) surgeon preference regarding intraoperative leak testing; (9) nasogastric intubation needed only for Veress access; (10) to avoid abdominal drains and urinary catheters; (11) to prevent ileus by discontinuing intravenous fluids early; (12) postoperative analgesia with acetaminophen, short-term NSAIDS, and minimal opioids; (13) to resume full fluid diet on first postoperative day; (14) early telephone follow-up with full clinic follow-up at 3-4 weeks.

CONCLUSIONS

The purpose of addressing these ERAS elements is to develop guidelines that can be implemented and practiced clinically. ERAS is an excellent model that improves surgical efficiency and acts as a common perioperative pathway. In the interim, this multimodal bariatric perioperative guideline serves as a common consensus point for Canadian bariatric surgeons.

Guidelines for Perioperative Care in Elective Colorectal Surgery: Enhanced Recovery After Surgery (ERAS®) Society Recommendations: 2018

BACKGROUND

This is the fourth updated Enhanced Recovery After Surgery (ERAS®) Society guideline presenting a consensus for optimal perioperative care in colorectal surgery and providing graded recommendations for each ERAS item within the ERAS® protocol.

METHODS

A wide database search on English literature publications was performed. Studies on each item within the protocol were selected with particular attention paid to meta-analyses, randomised controlled trials and large prospective cohorts and examined, reviewed and graded according to Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system.

RESULTS

All recommendations on ERAS® protocol items are based on best available evidence; good-quality trials; meta-analyses of good-quality trials; or large cohort studies. The level of evidence for the use of each item is presented accordingly.

CONCLUSIONS

The evidence base and recommendation for items within the multimodal perioperative care pathway are presented by the ERAS® Society in this comprehensive consensus review.

Perioperative hypothermia during colectomy: when do patients get cold?

BACKGROUND

Hypothermia has been associated with an increase in the rate of infectious complications following colectomy. We hypothesized that a substantial fraction of temperature loss in patients undergoing elective colectomy occurs prior to operation.

METHODS

Temperature data were collected from 105 consecutive patients undergoing elective colectomy at a single institution.

RESULTS

The study population consisted of 105 patients; 67(64%) male, median age 59 years (range 17-95 years), median body mass index 27 kg/m² (range 15-48 kg/m²). Median preoperative temperature was 36.7 °C (range 35.2-39.2 °C), dropping to 35.7 °C (range 34.0-37.3 °C) immediately following intubation and then rising to 36.2 °C (range 34.0-38.0 °C) prior to leaving the operating room. The median first postoperative temperature was 36.3 °C (range 34.4-37.7 °C). Temperatures were significantly different from one another (p < 0.05, ANOVA), except for the last operative and first postoperative temperature. A first postoperative temperature of ≥ 36.0 °C (meeting Surgical Care Improvement criteria Inf-10) was achieved in 78 (74%) of patients. A preoperative temperature of ≥ 36.5 °C was associated with a first postoperative temperature of ≥ 36.0 °C, but operative approach (laparoscopic versus open) was not.

CONCLUSIONS

Most temperature loss occurs prior to operation in patients undergoing colectomy. Patients are rewarmed during the operative procedure. The time period prior to operation should be the focus of efforts designed to ensure normothermia.

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.

A review of the reporting of web searching to identify studies for Cochrane systematic reviews

The literature searches that are used to identify studies for inclusion in a systematic review should be comprehensively reported. This ensures that the literature searches are transparent and reproducible, which is important for assessing the strengths and weaknesses of a systematic review and re-running the literature searches when conducting an update review. Web searching using search engines and the websites of topically relevant organisations is sometimes used as a supplementary literature search method. Previous research has shown that the reporting of web searching in systematic reviews often lacks important details and is thus not transparent or reproducible. Useful details to report about web searching include the name of the search engine or website, the URL, the date searched, the search strategy, and the number of results. This study reviews the reporting of web searching to identify studies for Cochrane systematic reviews published in the 6-month period August 2016 to January 2017 (n = 423). Of these reviews, 61 reviews reported using web searching using a search engine or website as a literature search method. In the majority of reviews, the reporting of web searching was found to lack essential detail for ensuring transparency and reproducibility, such as the search terms. Recommendations are made on how to improve the reporting of web searching in Cochrane systematic reviews.

Effects of low intraperitoneal pressure and a warmed, humidified carbon dioxide gas in laparoscopic surgery: a randomized clinical trial

Laparoscopic surgery technology continues to advance. However, much less attention has been focused on how alteration of the laparoscopic surgical environment might improve clinical outcomes. We conducted a randomized, 2 × 2 factorial trial to evaluate whether low intraperitoneal pressure (IPP) (8 mmHg) and/or warmed, humidified CO₂ (WH) gas are better for minimizing the adverse impact of a CO₂ pneumoperitoneum on the peritoneal environment during laparoscopic surgery and for improving clinical outcomes compared to the standard IPP (12 mmHg) and/or cool and dry CO₂ (CD) gas. Herein we show that low IPP and WH gas may decrease inflammation in the laparoscopic surgical environment, resulting in better clinical outcomes. Low IPP and/or WH gas significantly lowered expression of inflammation-related genes in peritoneal tissues compared to the standard IPP and/or CD gas. The odds ratios of a visual analogue scale (VAS) pain score >30 in the ward was 0.18 (95% CI: 0.06, 0.52) at 12 hours and 0.06 (95% CI: 0.01, 0.26) at 24 hours in the low IPP group versus the standard IPP group, and 0.16 (95% CI: 0.05, 0.49) at 0 hours and 0.29 (95% CI: 0.10, 0.79) at 12 hours in the WH gas group versus the CD gas group.

Gases for establishing pneumoperitoneum during laparoscopic abdominal surgery

BACKGROUND

This is an update of the review published in 2013.Laparoscopic surgery is now widely performed to treat various abdominal diseases. Currently, carbon dioxide is the most frequently used gas for insufflation of the abdominal cavity (pneumoperitoneum). Although carbon dioxide meets most of the requirements for pneumoperitoneum, the absorption of carbon dioxide may be associated with adverse events. People with high anaesthetic risk are more likely to experience cardiopulmonary complications and adverse events, for example hypercapnia and acidosis, which has to be avoided by hyperventilation. Therefore, other gases have been introduced as alternatives to carbon dioxide for establishing pneumoperitoneum.

OBJECTIVES

To assess the safety, benefits, and harms of different gases (i.e. carbon dioxide, helium, argon, nitrogen, nitrous oxide, and room air) used for establishing pneumoperitoneum in participants undergoing laparoscopic general abdominal or gynaecological pelvic surgery.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 9), Ovid MEDLINE (1950 to September 2016), Ovid Embase (1974 to September 2016), Science Citation Index Expanded (1970 to September 2016), Chinese Biomedical Literature Database (CBM) (1978 to September 2016), ClinicalTrials.gov (September 2016), and World Health Organization International Clinical Trials Registry Platform (September 2016).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different gases for establishing pneumoperitoneum in participants (irrespective of age, sex, or race) undergoing laparoscopic abdominal or gynaecological pelvic surgery under general anaesthesia.

DATA COLLECTION AND ANALYSIS

Two review authors identified the trials for inclusion, collected the data, and assessed the risk of bias independently. We performed the meta-analyses using Review Manager 5. We calculated risk ratio (RR) for dichotomous outcomes (or Peto odds ratio for very rare outcomes), and mean difference (MD) or standardised mean difference (SMD) for continuous outcomes with 95% confidence intervals (CI). We used GRADE to rate the quality of evidence, MAIN RESULTS: We included nine RCTs, randomising 519 participants, comparing different gases for establishing pneumoperitoneum: nitrous oxide (three trials), helium (five trials), or room air (one trial) was compared to carbon dioxide. Three trials randomised participants to nitrous oxide pneumoperitoneum (100 participants) or carbon dioxide pneumoperitoneum (96 participants). None of the trials was at low risk of bias. There was insufficient evidence to determine the effects of nitrous oxide and carbon dioxide on cardiopulmonary complications (RR 2.00, 95% CI 0.38 to 10.43; two studies; 140 participants; very low quality of evidence), or surgical morbidity (RR 1.01, 95% CI 0.18 to 5.71; two studies; 143 participants; very low quality of evidence). There were no serious adverse events related to either nitrous oxide or carbon dioxide pneumoperitoneum (three studies; 196 participants; very low quality of evidence). We could not combine data from two trials (140 participants) which individually showed lower pain scores (a difference of about one visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain) with nitrous oxide pneumoperitoneum at various time points on the first postoperative day, and this was rated asvery low quality .Four trials randomised participants to helium pneumoperitoneum (69 participants) or carbon dioxide pneumoperitoneum (75 participants) and one trial involving 33 participants did not state the number of participants in each group. None of the trials was at low risk of bias. There was insufficient evidence to determine the effects of helium or carbon dioxide on cardiopulmonary complications (RR 1.46, 95% CI 0.35 to 6.12; three studies; 128 participants; very low quality of evidence) or pain scores (visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain; MD 0.49 cm, 95% CI -0.28 to 1.26; two studies; 108 participants; very low quality of evidence). There were three serious adverse events (subcutaneous emphysema) related to helium pneumoperitoneum (three studies; 128 participants; very low quality of evidence).One trial randomised participants to room air pneumoperitoneum (70 participants) or carbon dioxide pneumoperitoneum (76 participants). The trial was at unclear risk of bias. There were no cardiopulmonary complications or serious adverse events observed related to either room air or carbon dioxide pneumoperitoneum (both outcomes very low quality of evidence). The evidence of lower hospital costs and reduced pain during the first postoperative day with room air pneumoperitoneum compared with carbon dioxide pneumoperitoneum (a difference of about one visual analogue score on a scale of 1 to 10 with lower numbers indicating less pain, was rated as very low quality of evidence.

AUTHORS' CONCLUSIONS

The quality of the current evidence is very low. The effects of nitrous oxide and helium pneumoperitoneum compared with carbon dioxide pneumoperitoneum are uncertain. Evidence from one trial of small sample size suggests that room air pneumoperitoneum may decrease hospital costs in people undergoing laparoscopic abdominal surgery. The safety of nitrous oxide, helium, and room air pneumoperitoneum has yet to be established.Further trials on this topic are needed, and should compare various gases (i.e. nitrous oxide, helium, argon, nitrogen, and room air) with carbon dioxide under standard pressure pneumoperitoneum with cold gas insufflation for people with high anaesthetic risk. Future trials should include outcomes such as complications, serious adverse events, quality of life, and pain.

Changes in the coelomic microclimate during carbon dioxide laparoscopy: morphological and functional implications

In this article the adverse effects of laparoscopic CO2 pneumoperitoneum and coelomic climate change, and their potential prevention by warmed, humidified carbon dioxide insufflation are reviewed. The use of pressurized cold, dry carbon dioxide (C02) pneumoperitoneum causes a number of local effects on the peritoneal mesothelium, as well as systemic effects. These can be observed at a macroscopic, microscopic, cellular and metabolic level. Local effects include evaporative cooling, oxidative stress, desiccation of mesothelium, disruption of mesothelial cell junctions and glycocalyx, diminished scavenging of reactive oxygen species, decreased peritoneal blood flow, peritoneal acidosis, peritoneal hypoxia or necrosis, exposure of the basal lamina and extracellular matrix, lymphocyte infiltration, and generation of peritoneal cytokines such as IL-1, IL-6, IL-8 and TNFα. Such damage is increased by high CO2 insufflation pressures and gas velocities and prolonged laparoscopic procedures. The resulting disruption of the glycocalyx, mesothelial cell barrier and exposure of the extracellular matrix creates a cascade of immunological and pro-inflammatory events and favours tumour cell implantation. Systemic effects include cardiopulmonary and respiratory changes, hypothermia and acidosis. Such coelomic climate change can be prevented by the use of lower insufflation pressures and preconditioned warm humidified CO2. By achieving a more physiological temperature, pressure and humidity, the coelomic microenvironment can be better preserved during pneumoperitoneum. This has the potential clinical benefits of maintaining isothermia and perfusion, reducing postoperative pain, preventing adhesions and inhibiting cancer cell implantation in laparoscopic surgery.

Effectiveness of active and passive warming for the prevention of inadvertent hypothermia in patients receiving neuraxial anesthesia: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Perioperative hypothermia is a common complication of anesthesia that can result in negative outcomes. The purpose of this review is to answer the question: Does the type of warming intervention influence the frequency or severity of inadvertent perioperative hypothermia (IPH) in surgical patients receiving neuraxial anesthesia?

DESIGN

Systematic review and meta-analysis.

SETTING

Perioperative care areas.

PATIENTS

Adults undergoing surgery with neuraxial anesthesia.

INTERVENTION

Perioperative active warming (AW) or passive warming (PW).

MEASUREMENTS

PubMed, CINAHL, Embase, and Cochrane Central Register of Controlled Trials were searched. Inclusion criteria were: randomized controlled trials; adults undergoing surgery with neuraxial anesthesia; comparison(s) of AW and PW; and temperature measured at end of surgery/upon arrival in the Postanesthesia Care Unit. Exclusion criteria were: no full-text available; not published in English; studies of: combined neuraxial and general anesthesia, warm intravenous or irrigation fluids without using AW, and rewarming after hypothermia. Two independent reviewers screened abstracts and titles, and selected records following full-text review. The Cochrane Collaboration's tool for assessing risk of bias was used to evaluate study quality. A random-effects model was used to calculate risk ratios for dichotomous data and mean differences for continuous data.

MAIN RESULTS

Of 1587 records, 25 studies (2048 patients) were included in the qualitative synthesis. Eleven studies (1189 patients) comparing AW versus PW were included in the quantitative analysis. Meta-analysis found that intraoperative AW is more effective than PW in reducing the incidence of IPH during neuraxial anesthesia (RR=0.71; 95% CI 0.61-0.83; p<0.0001; I²=32%). The qualitative synthesis revealed that IPH continues despite current AW technologies.

CONCLUSIONS

During neuraxial anesthesia, AW reduces IPH more effectively than PW. Even with AW, IPH persists in some patients. Continued innovation in AW technology and additional comparative effectiveness research studying different AW methods are needed.