Effects of intraoperative protective lung ventilation on postoperative pulmonary complications in patients with laparoscopic surgery: prospective, randomized and controlled trial

Machine learning model for predicting immediate postoperative desaturation using spirometry signal data

Postoperative desaturation is a common post-surgery pulmonary complication. The real-time prediction of postoperative desaturation can become a preventive measure, and real-time changes in spirometry data can provide valuable information on respiratory mechanics. However, there is a lack of related research, specifically on using spirometry signals as inputs to machine learning (ML) models. We developed an ML model and postoperative desaturation prediction index (DPI) by analyzing intraoperative spirometry signals in patients undergoing laparoscopic surgery. We analyzed spirometry data from patients who underwent laparoscopic, robot-assisted gynecologic, or urologic surgery, identifying postoperative desaturation as a peripheral arterial oxygen saturation level below 95%, despite facial oxygen mask usage. We fitted the ML model on two separate datasets collected during different periods. (Datasets A and B). Dataset A (Normal 133, Desaturation 74) was used for the entire experimental process, including ML model fitting, statistical analysis, and DPI determination. Dataset B (Normal 20, Desaturation 4) was only used for verify the ML model and DPI. Four feature categories-signal property, inter-/intra-position correlation, peak value/interval variability, and demographics-were incorporated into the ML models via filter and wrapper feature selection methods. In experiments, the ML model achieved an adequate predictive capacity for postoperative desaturation, and the performance of the DPI was unbiased.

Impact of ventilation strategies on pulmonary and cardiovascular complications in patients undergoing general anaesthesia for elective surgery: a systematic review and meta-analysis

BACKGROUND

Many RCTs have evaluated the influence of intraoperative tidal volume (tV), PEEP, and driving pressure on the occurrence of postoperative pulmonary complications, cardiovascular complications, and mortality in adult patients. Our meta-analysis aimed to investigate the association between tV, PEEP, and driving pressure and the above-mentioned outcomes.

METHODS

We conducted a systematic review and meta-analysis of RCTs from inception to May 19, 2022. The primary outcome was the incidence of postoperative pulmonary complications; the secondary outcomes were intraoperative cardiovascular complications and 30-day mortality. Primary and secondary outcomes were evaluated stratifying patients in the following groups: (1) low tV (LV, tV 6-8 ml kg-1 and PEEP ≥5 cm H2O) vs high tV (HV, tV >8 ml kg-1 and PEEP=0 cm H2O); (2) higher PEEP (HP, ≥6 cm H2O) vs lower PEEP (LP, <6 cm H2O); and (3) driving pressure-guided PEEP (DP) vs fixed PEEP (FP).

RESULTS

We included 16 RCTs with a total sample size of 4993. The incidence of postoperative pulmonary complications was lower in patients treated with LV than with HV (OR=0.402, CI 0.280-0.577, P<0.001) and lower in DP than in FP group (OR=0.358, CI 0.187-0.684, P=0.002). Postoperative pulmonary complications did not differ between HP and LP groups; the incidence of intraoperative cardiovascular complications was higher in HP group (OR=1.385, CI 1.027-1.867, P=0.002). The 30-day mortality was not influenced by the ventilation strategy.

CONCLUSIONS

Optimal intraoperative mechanical ventilation is unclear; however, our meta-analysis showed that low tidal volume and driving pressure-guided PEEP strategies were associated with a reduction in postoperative pulmonary complications.

Individualised positive end-expiratory pressure titrated intra-operatively by electrical impedance tomography optimises pulmonary mechanics and reduces postoperative atelectasis: A randomised controlled trial

BACKGROUND

A protective intra-operative lung ventilation strategy has been widely recommended for laparoscopic surgery. However, there is no consensus regarding the optimal level of positive end-expiratory pressure (PEEP) and its effects during pneumoperitoneum. Electrical impedance tomography (EIT) has recently been introduced as a bedside tool to monitor lung ventilation in real-time.

OBJECTIVE

We hypothesised that individually titrated EIT-PEEP adjusted to the surgical intervention would improve respiratory mechanics during and after surgery.

DESIGN

Randomised controlled trial.

SETTING

First Medical Centre of Chinese PLA General Hospital, Beijing.

PATIENTS

Seventy-five patients undergoing robotic-assisted laparoscopic hepatobiliary and pancreatic surgery under general anaesthesia.

INTERVENTIONS

Patients were randomly assigned 2 : 1 to individualised EIT-titrated PEEP (PEEPEIT; n = 50) or traditional PEEP 5 cmH2O (PEEP5 cmH2O; n = 25). The PEEPEIT group received individually titrated EIT-PEEP during pneumoperitoneum. The PEEP5 cmH2O group received PEEP of 5 cmH2O during pneumoperitoneum.

MAIN OUTCOME MEASURES

The primary outcome was respiratory system compliance during laparoscopic surgery. Secondary outcomes were individualised PEEP levels, oxygenation, respiratory and haemodynamic status, and occurrence of postoperative pulmonary complications (PPCs) within 7 days.

RESULTS

Compared with PEEP5 cmH2O, patients who received PEEPEIT had higher respiratory system compliance (mean values during surgery of 44.3 ± 11.3 vs. 31.9 ± 6.6, ml cmH2O-1; P < 0.001), lower driving pressure (11.5 ± 2.1 vs. 14.0 ± 2.4 cmH2O; P < 0.001), better oxygenation (mean PaO2/FiO2 427.5 ± 28.6 vs. 366.8 ± 36.4; P = 0.003), and less postoperative atelectasis (19.4 ± 1.6 vs. 46.3 ± 14.8 g of lung tissue mass; P = 0.003). Haemodynamic values did not differ significantly between the groups. No adverse effects were observed during surgery.

CONCLUSION

Individualised PEEP by EIT may improve intra-operative pulmonary mechanics and oxygenation without impairing haemodynamic stability, and decrease postoperative atelectasis.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (www.chictr.org.cn) identifier: ChiCTR2100045166.

Effect of perioperative airway management on postoperative outcomes of colorectal cancer patients with sarcopenia

BACKGROUND

It is common for colorectal cancer patients to have sarcopenia as a comorbidity, which has been shown to have a negative impact on prognosis after surgery. This study explored whether implementing a novel care program could improve postoperative outcomes in colorectal cancer patients with sarcopenia.

METHODS

We retrospectively analyzed the clinical data of patients diagnosed with sarcopenia before undergoing radical colorectal cancer surgery. We divided the patients into two groups according to the time point of program implementation and, compared the clinical characteristics and postoperative outcomes of these two groups.

RESULTS

A total of 227 patients were included in the study. The baseline clinical characteristics of the two groups were similar. Compared with the control group, patients in the implementation group had a significantly lower rate of total complications (18.5% vs. 30.3%, P = 0.041), a significantly lower rate of pulmonary complications (2.8% vs. 10.9%, P = 0.017), and a significantly shorter postoperative hospital stay (12 days vs. 14 days, P = 0.001). Implementation of perioperative airway management (P = 0.018) was shown to be a protective factor against pulmonary complications in colorectal cancer patients with sarcopenia.

CONCLUSION

The perioperative airway management program implemented at our center was easy to perform and can effectively improve short-term postoperative outcomes in colorectal cancer patients with sarcopenia.

Effect of protective lung ventilation on pulmonary complications after laparoscopic surgery: a meta-analysis of randomized controlled trials

Introduction

Compared with traditional open surgery, laparoscopic surgery is widely used in surgery, with the advantages of being minimally invasive, having good cosmetic effects, and having short hospital stays, but in laparoscopic surgery, pneumoperitoneum and the Trendelenburg position can cause complications, such as atelectasis. Recently, several studies have shown that protective lung ventilation strategies are protective for abdominal surgery, reducing the incidence of postoperative pulmonary complications (PPCs). Ventilator-associated lung injury can be reduced by protective lung ventilation, which includes microtidal volume (4-8 mL/kg) ventilation and positive end-expiratory pressure (PEEP). Therefore, we used randomized, controlled trials (RCTs) to assess the results on this topic, and RCTs were used for meta-analysis to further evaluate the effect of protective lung ventilation on pulmonary complications in patients undergoing laparoscopic surgery.

Methods

In this meta-analysis, we searched the relevant literature contained in six major databases-CNKI, CBM, Wanfang Medical, Cochrane, PubMed, and Web of Science-from their inception to October 15, 2022. After screening the eligible literature, a randomized, controlled method was used to compare the occurrence of postoperative pulmonary complications when a protective lung ventilation strategy and conventional lung ventilation strategy were applied to laparoscopic surgery. After statistical analysis, the results were verified to be statistically significant.

Results

Twenty-three trials were included. Patients receiving protective lung ventilation were 1.17 times less likely to develop pulmonary complications after surgery than those receiving conventional lung ventilation (hazard ratio [RR] 0.18, 95% confidence interval [CI] 1.13-1.22; I² = 0%). When tested for bias (P = 0.36), the result was statistically significant. Patients with protective lung ventilation were less likely to develop pulmonary complications after laparoscopic surgery.

Conclusion

Compared with conventional mechanical ventilation, protective lung ventilation reduces the incidence of postoperative pulmonary complications. For patients undergoing laparoscopic surgery, we suggest the use of protective lung ventilation, which is effective in reducing the incidence of lung injury and pulmonary infection. Implementation of a low tidal volume plus moderate positive end-expiratory pressure strategy reduces the risk of postoperative pulmonary complications.

Postoperative Pulmonary Complications and Perioperative Strategies: A Systematic Review

The occurrence of postoperative pulmonary complications (PPCs) is frequently observed and has been linked to elevated levels of morbidity and mortality, which have adverse effects on both clinical and financial outcomes in healthcare settings. This systematic review aims to present the evidence that supports our comprehension of PPCs and emphasize the circumstances that necessitate the use of postoperative noninvasive ventilation (PNIV) or re-intubation with postoperative mechanical ventilation (POMV). A search was conducted on the National Library of Medicine's Pubmed database and Cochrane Library until November 29, 2020, to find published reports of randomized control trials (RCTs) that assessed postoperative pulmonary complications. Data related to the prevalence of PPCs and the use of PNIV, POMV, and length of hospital stay were extracted from all the studies. For the analysis, a total of 13 studies involving 6,609 patients were included, and out of these, four RCTs reported statistically significant results. The use of protective lung ventilation (PLV) with low tidal volume and positive end-expiratory pressure (PEEP) during intraoperative ventilation, along with pressure-controlled (PCV) ventilation, as well as the postoperative ventilation strategy of continuous positive airway pressure (CPAP) combined with standard oxygen therapy were the only techniques that demonstrated a clear reduction in the incidence of PPCs. Furthermore, the use of PLV with low tidal volume and PEEP and intraoperative mechanical ventilation with a vital capacity maneuver followed by 10 cm H2O of PEEP were found to decrease the requirement for postoperative noninvasive ventilation. CPAP with standard oxygen therapy was the only intervention that reduced the need for reintubation. Various ventilation strategies are available for both intraoperative and postoperative periods with the goal of decreasing the need for postoperative noninvasive ventilation (PNIV) or re-intubation with postoperative mechanical ventilation (POMV).

Low tidal volume ventilation for patients undergoing laparoscopic surgery: a secondary analysis of a randomised clinical trial

BACKGROUND

We recently reported the results for a large randomized controlled trial of low tidal volume ventilation (LTVV) versus conventional tidal volume (CTVV) during major surgery when positive end expiratory pressure (PEEP) was equal between groups. We found no difference in postoperative pulmonary complications (PPCs) in patients who received LTVV. However, in the subgroup of patients undergoing laparoscopic surgery, LTVV was associated with a numerically lower rate of PPCs after surgery. We aimed to further assess the relationship between LTVV versus CTVV during laparoscopic surgery.

METHODS

We conducted a post-hoc analysis of this pre-specified subgroup. All patients received volume-controlled ventilation with an applied PEEP of 5 cmH₂O and either LTVV (6 mL/kg predicted body weight [PBW]) or CTVV (10 mL/kg PBW). The primary outcome was the incidence of a composite of PPCs within seven days.

RESULTS

Three hundred twenty-eight patients (27.2%) underwent laparoscopic surgeries, with 158 (48.2%) randomised to LTVV. Fifty two of 157 patients (33.1%) assigned to LTVV and 72 of 169 (42.6%) assigned to conventional tidal volume developed PPCs within 7 days (unadjusted absolute difference, - 9.48 [95% CI, - 19.86 to 1.05]; p = 0.076). After adjusting for pre-specified confounders, the LTVV group had a lower incidence of the primary outcome than patients receiving CTVV (adjusted absolute difference, - 10.36 [95% CI, - 20.52 to - 0.20]; p = 0.046).

CONCLUSION

In this post-hoc analysis of a large, randomised trial of LTVV we found that during laparoscopic surgeries, LTVV was associated with a significantly reduced PPCs compared to CTVV when PEEP was applied equally between both groups.

TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry no: 12614000790640.

Risk factors for pulmonary complications after laparoscopic liver resection: a multicenter retrospective analysis

BACKGROUND

Postoperative pulmonary complications (PPCs) are among the most common complications after liver resection. Although the application of laparoscopy has reduced the incidence of PPCs, the rate of PPCs after laparoscopic liver resection (LLR) remains high and the risk factors for the same are unclear. Therefore, this study aimed to determine the risk factors for PPCs after LLR.

METHODS

In this multicenter study, 296 patients underwent LLR from January 2019 to December 2020. Demographic data, pathological variables, and perioperative variables were reviewed. Univariate and multivariate analyses were performed to identify the independent risk factors for PPCs.

RESULTS

Of the 296 patients, 80 (27.0%) developed PPCs. Patients with PPCs had significantly increased total costs, operation costs, length of stays, and postoperative hospital stays. Multivariate analysis identified three independent risk factors for PPCs after LLR: smoking [Odds ratio (OR): 5.413, 95% confidence intervals (CI): 2.446-11.978, P =  < 0.001], location of lesion in segment 7 or 8 (OR 3.134, 95% CI 1.593-6.166, P = 0.001), duration of liver ischemia (OR 1.038, 95% CI 1.022-1.054, P < 0.001), and presence of intraoperative hypothermia (OR 3.134, 95% CI 1.593-6.166, P < 0.001).

CONCLUSION

Smoking, location of lesion in segment 7 or 8, duration of liver ischemia and intraoperative hypothermia were independent risk factors for PPCs which significantly increased the length of stays and burden of healthcare costs.

Reliability of stroke volume or pulse pressure variation as dynamic predictors of fluid responsiveness in laparoscopic surgery: a systematic review

The reliability of stroke volume variation (SVV) and pulse pressure variation (PPV) in predicting fluid responsiveness during laparoscopic surgery remains unclear. We conducted the present systematic review to summarize the current evidence. We reviewed studies that investigated the reliability of SVV and PPV in laparoscopic surgery. Seven studies were included in the final analysis. Two studies demonstrated that the area under the receiver operating characteristic curve (AUROC) for SVV was less than 0.8, and five studies reported that the AUROC was > 0.8. The pooled AUROC for SVV and PPV was more than 0.8 with high heterogeneities between the included studies. Most individual studies have suggested that SVV and PPV are sufficiently reliable for predicting fluid responsiveness during laparoscopic surgery. However, the limited number of patients, varied apparatus used to define fluid responsiveness, diverse definitions of fluid responsiveness, and different fluids used to perform fluid challenges in the included studies render firm conclusions about SVV's and PPV's reliability impossible.

Effect of positive end-expiratory pressure on pulmonary compliance and pulmonary complications in patients undergoing robot-assisted laparoscopic radical prostatectomy: a randomized control trial

Background

To observe the effects of different positive end-expiratory pressure (PEEP) ventilation strategies on pulmonary compliance and complications in patients undergoing robotic-assisted laparoscopic prostate surgery.

Methods

A total of 120 patients with the American Society of Anesthesiologists Physical Status Class I or II who underwent elective robotic-assisted laparoscopic prostatectomy were enrolled. We randomized the patients divided into divided into three groups of 40 patients each: PEEP0, PEEP5, or PEEP10. Master Anesthetist used volume control ventilation intraoperatively with an intraoperative deep muscle relaxation strategy. Respiratory mechanics indexes were recorded at six time-points: 10 mimuts after anaesthesia induction, immediately after pneumoperitoneum establishment, 30 min, 60 min, 90 min, and at the end of pneumoperitoneum. Arterial blood gas analysis and oxygenation index calculation were performed 10 mimuts after anaesthesia induction, 60 mimuts after pneumoperitoneum, and after tracheal extubation. Postoperative pulmonary complications were also recorded.

Results

After pneumoperitoneum, peak inspiratory pressure (Ppeak), plateau pressure (Pplat), mean pressure (Pmean), driving pressure (ΔP), and airway resistance (Raw) increased significantly, and pulmonary compliance (Crs) decreased, persisting during pneumoperitoneum in all groups. Between immediately after pneumoperitoneum establishment, 30 min, 60 min, and 90 min, pulmonary compliance in the 10cmH2OPEEP group was higher than in the 5cmH2OPEEP (P < 0.05) and 0cmH2OPEEP groups(P < 0.05). The driving pressure (ΔP) immediately after pneumoperitoneum establishment, at 30 min, 60 min, and 90 min in the 10cmH2OPEEP group was lower than in the 5cmH2OPEEP (P < 0.05) and 0cmH2OPEEP groups (P < 0.05). Sixty min after pneumoperitoneum and tracheal extubation, the PaCO2 did not differ significantly among the three groups (P > 0.05). The oxygenation index (PaO2/FiO2) was higher in the PEEP5 group than in the PEEP0 and PEEP10 groups 60 min after pneumoperitoneum and after tracheal extubation, with a statistically significant difference (P < 0.05). In postoperative pulmonary complications, the incidence of atelectasis was higher in the PEEP0 group than in the PEEP5 and PEEP10 groups, with a statistically significant difference (p < 0.05).

Conclusion

The use of PEEP at 5cmH2O during RARP increases lung compliance, improves intraoperative oxygenation index and reduces postoperative atelectasis.

Trial registration

This study was registered in the China Clinical Trials Registry on May 30, 2020 (Registration No. ChiCTR2000033380).

Ventilation Strategies During General Anesthesia for Noncardiac Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

The optimal ventilation strategy during general anesthesia is unclear. This systematic review investigated the relationship between ventilation targets or strategies (eg, positive end-expiratory pressure [PEEP], tidal volume, and recruitment maneuvers) and postoperative outcomes.

METHODS

PubMed and Embase were searched on March 8, 2021, for randomized trials investigating the effect of different respiratory targets or strategies on adults undergoing noncardiac surgery. Two investigators reviewed trials for relevance, extracted data, and assessed risk of bias. Meta-analyses were performed for relevant outcomes, and several subgroup analyses were conducted. The certainty of evidence was evaluated using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

This review included 63 trials with 65 comparisons. Risk of bias was intermediate for all trials. In the meta-analyses, lung-protective ventilation (ie, low tidal volume with PEEP) reduced the risk of combined pulmonary complications (odds ratio [OR], 0.37; 95% confidence interval [CI], 0.28-0.49; 9 trials; 1106 patients), atelectasis (OR, 0.39; 95% CI, 0.25-0.60; 8 trials; 895 patients), and need for postoperative mechanical ventilation (OR, 0.36; 95% CI, 0.13-1.00; 5 trials; 636 patients). Recruitment maneuvers reduced the risk of atelectasis (OR, 0.44; 95% CI, 0.21-0.92; 5 trials; 328 patients). We found no clear effect of tidal volume, higher versus lower PEEP, or recruitment maneuvers on postoperative pulmonary complications when evaluated individually. For all comparisons across targets, no effect was found on mortality or hospital length of stay. No effect measure modifiers were found in subgroup analyses. The certainty of evidence was rated as very low, low, or moderate depending on the intervention and outcome.

CONCLUSIONS

Although lung-protective ventilation results in a decrease in pulmonary complications, randomized clinical trials provide only limited evidence to guide specific ventilation strategies during general anesthesia for adults undergoing noncardiac surgery.

Optimized ventilation strategy for surgery on patients with obesity from the perspective of lung protection: A network meta-analysis

Objectives

New ventilation modes have been proposed to support the perioperative treatment of patients with obesity, but there is a lack of consensus regarding the optimal strategy. Therefore, a network meta-analysis update of 13 ventilation strategies was conducted to determine the optimal mode of mechanical ventilation as a protective ventilation strategy decreases pulmonary atelectasis caused by inflammation.

Methods

The following databases were searched: MEDLINE; Cochrane Library; Embase; CINAHL; Google Scholar; and Web of Science for randomized controlled trials of mechanical ventilation in patients with obesity published up to May 1, 2022.

Results

Volume-controlled ventilation with individualized positive end-expiratory pressure and a recruitment maneuver (VCV+PEEPind+RM) was found to be the most effective strategy for improving ratio of the arterial O2 partial pressure to the inspiratory O2 concentration (PaO2/FiO2), and superior to pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), volume-controlled ventilation with recruitment maneuver (VCV+RM), volume-controlled ventilation with low positive end-expiratory pressure (VCV+lowPEEP), volume-controlled ventilation with lower positive expiratory end pressure (PEEP) and recruitment maneuver (VCV+lowPEEP+RM), and the mean difference [MD], the 95% confidence intervals [CIs] and [quality of evidence] were: 162.19 [32.94, 291.45] [very low]; 180.74 [59.22, 302.27] [low]; 171.07 [40.60, 301.54] [very low]; 135.14 [36.10, 234.18] [low]; and 139.21 [27.08, 251.34] [very low]. Surface under the cumulative ranking curve (SUCRA) value showed VCV+PEEPind+RM was the best strategy for improving PaO2/FiO2 (SUCRA: 0.963). VCV with high positive PEEP and recruitment maneuver (VCV+highPEEP+RM) was more effective in decreasing postoperative pulmonary atelectasis than the VCV+lowPEEP+RM strategy. It was found that volume-controlled ventilation with high positive expiratory end pressure (VCV+highPEEP), risk ratio [RR] [95% CIs] and [quality of evidence], 0.56 [0.38, 0.81] [moderate], 0.56 [0.34, 0.92] [moderate]. SUCRA value ranked VCV+highPEEP+RM the best strategy for improving postoperative pulmonary atelectasis intervention (SUCRA: 0.933). It should be noted that the quality of evidence was in all cases very low or only moderate.

Conclusions

This research suggests that VCV+PEEPind+RM is the optimal ventilation strategy for patients with obesity and is more effective in increasing PaO2/FiO2, improving lung compliance, and among the five ventilation strategies for postoperative atelectasis, VCV+highPEEP+RM had the greatest potential to reduce atelectasis caused by inflammation.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021288941.

Effect of Intraoperative Ventilation Strategies on Postoperative Pulmonary Complications: A Meta-Analysis

Introduction: The role of intraoperative ventilation strategies in subjects undergoing surgery is still contested. This meta-analysis study was performed to assess the relationship between the low tidal volumes strategy and conventional mechanical ventilation in subjects undergoing surgery. Methods: A systematic literature search up to December 2020 was performed in OVID, Embase, Cochrane Library, PubMed, and Google scholar, and 28 studies including 11,846 subjects undergoing surgery at baseline and reporting a total of 2,638 receiving the low tidal volumes strategy and 3,632 receiving conventional mechanical ventilation, were found recording relationships between low tidal volumes strategy and conventional mechanical ventilation in subjects undergoing surgery. Odds ratio (OR) or mean difference (MD) with 95% confidence intervals (CIs) were calculated between the low tidal volumes strategy vs. conventional mechanical ventilation using dichotomous and continuous methods with a random or fixed-effect model. Results: The low tidal volumes strategy during surgery was significantly related to a lower rate of postoperative pulmonary complications (OR, 0.60; 95% CI, 0.44-0.83, p < 0.001), aspiration pneumonitis (OR, 0.63; 95% CI, 0.46-0.86, p < 0.001), and pleural effusion (OR, 0.72; 95% CI, 0.56-0.92, p < 0.001) compared to conventional mechanical ventilation. However, the low tidal volumes strategy during surgery was not significantly correlated with length of hospital stay (MD, -0.48; 95% CI, -0.99-0.02, p = 0.06), short-term mortality (OR, 0.88; 95% CI, 0.70-1.10, p = 0.25), atelectasis (OR, 0.76; 95% CI, 0.57-1.01, p = 0.06), acute respiratory distress (OR, 1.06; 95% CI, 0.67-1.66, p = 0.81), pneumothorax (OR, 1.37; 95% CI, 0.88-2.15, p = 0.17), pulmonary edema (OR, 0.70; 95% CI, 0.38-1.26, p = 0.23), and pulmonary embolism (OR, 0.65; 95% CI, 0.26-1.60, p = 0.35) compared to conventional mechanical ventilation. Conclusions: The low tidal volumes strategy during surgery may have an independent relationship with lower postoperative pulmonary complications, aspiration pneumonitis, and pleural effusion compared to conventional mechanical ventilation. This relationship encouraged us to recommend the low tidal volumes strategy during surgery to avoid any possible complications.

Effects of deep neuromuscular block with low-pressure pneumoperitoneum on respiratory mechanics and biotrauma in a steep Trendelenburg position

We hypothesized that deep neuromuscular blockade (NMB) with low-pressure pneumoperitoneum (PP) would improve respiratory mechanics and reduce biotrauma compared to moderate NMB with high-pressure PP in a steep Trendelenburg position. Seventy-four women undergoing robotic gynecologic surgery were randomly assigned to two equal groups. Moderate NMB group was maintained with a train of four count of 1–2 and PP at 12 mmHg. Deep NMB group was maintained with a post-tetanic count of 1–2 and PP at 8 mmHg. Inflammatory cytokines were measured at baseline, at the end of PP, and 24 h after surgery. Interleukin-6 increased significantly from baseline at the end of PP and 24 h after the surgery in moderate NMB group but not in deep NMB group (P_group*time = 0.036). The peak inspiratory, driving, and mean airway pressures were significantly higher in moderate NMB group than in deep NMB group at 15 min and 60 min after PP (P_group*time = 0.002, 0.003, and 0.048, respectively). In conclusion, deep NMB with low-pressure PP significantly suppressed the increase in interleukin-6 developed after PP, by significantly improving the respiratory mechanics compared to moderate NMB with high-pressure PP during robotic surgery.

The Potential Role of Lung-Protective Ventilation in Preventing Postoperative Delirium in Elderly Patients Undergoing Prone Spinal Surgery: A Preliminary Study

Background

Postoperative delirium (POD) is a frequent complication in elderly patients, usually occurring within a few days after surgery. This study investigated the effect of lung-protective ventilation (LPV) on POD in elderly patients undergoing spinal surgery and the mechanism by which LPV suppresses POD.

Material/Methods

Seventy-one patients aged ≥65 years were randomized to receive LPV or conventional mechanical ventilation (MV), consisting of intermittent positive pressure ventilation following induction of anesthesia. The tidal volume in patients who received MV was 8 ml/kg predicted body weight (PBW), and the ventilation frequency was 12 times/min. The tidal volume in patients who received LPV was 6 ml/kg PBW, the positive end-expiratory pressure was 5 cmH₂O, and the ventilation frequency was 15 times/min, with a lung recruitment maneuver performed every 30 min. Blood samples were collected immediately before anesthesia induction (T₀), 10 min (T₁) and 60 min (T₂) after turning over, immediately after the operation (T₃), and 15 min after extubation (T₄) for blood gas analysis. Simultaneous cerebral oxygen saturation (rSO₂) and cerebral desaturation were recorded. Preoperative and postoperative serum concentrations of interleukin (IL)-6, IL-10 and glial fibrillary acidic protein (GFAP) were measured by ELISA. POD was assessed by nursing delirium screening score.

Results

Compared with the MV group, pH was lower and PaCO₂ higher in the LPV group at T₂. In addition PaO₂, SaO₂, and PaO₂/FiO₂ were higher at T₁, and T₄, and rSO₂ was higher at T₃, and T₄ in the LPV than in the MV group (P<0.05 each). Postoperative serum GFAP and IL-6 were lower and IL-10 higher in the LPV group. The incidences of cerebral desaturation and POD were significantly lower in the LPV group (P<0.05).

Conclusions

LPV may reduce POD in elderly patients undergoing spinal surgery by inhibiting inflammation and improving cerebral oxygen metabolism.

Effects of an Alveolar Recruitment Maneuver During Lung Protective Ventilation on Postoperative Pulmonary Complications in Elderly Patients Undergoing Laparoscopy

Purpose

Controversy remains over whether alveolar recruitment maneuvers (ARMs) can reduce postoperative pulmonary complications. We hypothesized that performing an ARM in addition to lung protective ventilation (LPV) could improve intraoperative arterial oxygenation and postoperative pulmonary complications (PPCs) in elderly patients undergoing laparoscopy in the Trendelenburg position.

Patients and Methods

Sixty-two patients (aged 65-85) scheduled for laparoscopic low anterior resection were randomized to receive LPV only (LPV group, n = 32) or LPV with an ARM (ARM group, n = 30). LPV was set to a tidal volume of 6 mL/kg with a positive end expiratory pressure (PEEP) of 5 cmH₂O. The ARM was performed by serially increasing the PEEP to 10 cmH₂O for 3 breaths, 15 cmH₂O for 3 breaths, then 20 cmH₂O for 10 breaths, both immediately before and after abdominal insufflation. The primary end-point was the frequency of PPCs such as desaturation (SpO₂ <90%), atelectasis, and pneumonia. Secondary end-points were changes in intraoperative respiratory and gas exchange parameters and hemodynamic variables.

Results

One patient in the LPV group experienced desaturation on the first postoperative day. The frequency of chest X-ray abnormalities such as atelectasis or pleural effusion was comparable between groups (6 (19%) and 5 (17%) patients, respectively, P = 0.676). Changes in other respiratory, gas exchange and hemodynamic parameters over time were not significantly different between the groups. However, vasopressor requirements during surgery were higher in the ARM than the LPV group (9 (30%) and 2 (6%) patients, respectively, P = 0.014).

Conclusion

This study suggests that performing an ARM during LPV may not improve postoperative respiratory outcomes and intraoperative oxygenation compared to LPV alone in geriatric patients undergoing laparoscopy in the Trendelenburg position. In addition, since the ARM could cause a significant deterioration in hemodynamic parameters, applying ARM to elderly patients should be carefully considered.

Laparoscopic versus open resection for elderly patients with gastric cancer: a double-center study with propensity score matching method

PURPOSE

The applicability of laparoscopic-assisted radical gastrectomy for elderly patients with gastric cancer is still not well clarified. The aim of this double-center study was to explore the feasibility and effectiveness of laparoscopic-assisted radical gastrectomy on elderly patients with gastric cancer.

METHODS

We prospectively collected data of patients who underwent gastrectomy for cancer in two centers from June 2016 to December 2019. Propensity score matching was performed at a ratio of 1:1 to compare the laparoscopic-assisted radical gastrectomy group and open radical gastrectomy group. Univariate analyses and multivariate logistic regression analyses evaluating the risk factors for total, surgical, and medical complications were performed.

RESULTS

A total of 481 patients with gastric cancer met the inclusion criteria and were included in this study. After propensity score analysis, 258 patients were matched each other (laparoscopic-assisted radical gastrectomy (LAG) group, n = 129; open radical gastrectomy (OG) group, n = 129). LAG group had lower rate of surgical complications (P = 0.009), lower rate of severe complications (P = 0.046), shorter postoperative hospital stay (P = 0.001), and lower readmission rate (P = 0.039). Multivariate analyses revealed that anemia, Charlson comorbidity index, and combined resection were independent risk factors in the LAG group, whereas body mass index and American Society of Anesthesiology grade in the OG group.

CONCLUSION

Laparoscopic-assisted radical gastrectomy was relative safe even effective in elderly gastric cancer patients. We should pay attention to the different risk factors when performing different surgical procedures for gastric cancer in elderly patients.

Comparison of the effects of deep and moderate neuromuscular block on respiratory system compliance and surgical space conditions during robot-assisted laparoscopic radical prostatectomy: a randomized clinical study

OBJECTIVE

Robot-assisted radical prostatectomy (RARP) requires pneumoperitoneum (Pnp) and a steep head-down position that may disturb respiratory system compliance (C_rs) during surgery. Our aim was to compare the effects of different degrees of neuromuscular block (NMB) on C_rs with the same Pnp pressure during RARP.

METHODS

One hundred patients who underwent RARP were enrolled and randomly allocated to a deep or moderate NMB group with 50 patients in each group. Rocuronium was administered to both groups: in the moderate NMB group to maintain 1-2 responses to train-of-four (TOF) stimulation; and in the deep NMB group to maintain no response to TOF stimulation and 1-2 responses in the post-tetanic count. Pnp pressure in both groups was 10 mmHg (1 mmHg=133.3 Pa). Peak inspiratory pressure (P_peak), mean pressure (P_mean), C_rs, and airway resistance (R_aw) were recorded after anesthesia induction and at 0, 30, 60, and 90 min of Pnp and post-Pnp. Surgical space conditions were evaluated after the procedure on a 4-point scale.

RESULTS

Immediately after the Pnp, P_peak, P_mean, and R_aw significantly increased, while C_rs decreased and persisted during Pnp in both groups. The results did not significantly differ between the two groups at any of the time points. There was no difference in surgical space conditions between groups. Body movements occurred in 14 cases in the moderate NMB group and in one case in the deep NMB group, and all occurred during obturator lymphadenectomy. A significant difference between the two groups was observed.

CONCLUSIONS

Under the same Pnp pressure in RARP, deep and moderate NMBs resulted in similar changes in C_rs, and in other respiratory mechanics and surgical space conditions. However, deep NMB significantly reduced body movements during surgery.

The Clinical Application of a Self-developed Gasless Laparoendoscopic Operation Field Formation Device on Patients Undergoing Cholecystectomy

BACKGROUND

We have designed a new gasless laparoscopic operation field formation (LOFF) device for cholecystectomy which was successfully tested on animal model. The goal of this study is to investigate the feasibility, safety and effectiveness of this LOFF device on patients undergoing cholecystectomy.

METHODS

Patients with cholecystolithiasis or gallbladder polyps who underwent single port cholecystectomy from June 2015 to May 2016 were retrospectively reviewed. Either the LOFF-assisted laparoendoscopic single-port surgery (LESS) (LOFF-LESS) or the traditional LESS was performed. Operation time, intraoperative bleeding, postoperative hospital stay, surgical complications, incision pain score, shoulder and back pain and cosmetic satisfaction were compared.

RESULTS

A total of 186 patients were included in this study, with 79 in the LOFF-LESS group and 107 in the LESS group. There was no significant difference between LOFF-LESS group and LESS group in operation field establishment time, cholecystectomy time, intraoperative bleeding, postoperative hospital stay, incision pain and cosmetic satisfaction. A lower intraoperative arterial carbon dioxide pressure was documented in the LOFF-LESS group (P<0.01). The incidence of postoperative shoulder and back pain was significantly lower in LOFF-LESS group (P<0.01).

CONCLUSION

LOFF-LESS has comparable benefits of traditional LESS; it deceases incidence of pneumoperitoneum related complications as well.

Effects of intra-operative positive end-expiratory pressure setting guided by oesophageal pressure measurement on oxygenation and respiratory mechanics during laparoscopic gynaecological surgery: A randomised controlled trial

BACKGROUND

The creation of pneumoperitoneum during laparoscopic surgery can lead to adverse effects on the respiratory system. Positive end-expiratory pressure (PEEP) plays an important role in mechanical ventilation during laparoscopic surgery.

OBJECTIVE

To evaluate whether PEEP setting guided by oesophageal pressure (Poeso) measurement would affect oxygenation and respiratory mechanics during laparoscopic gynaecological surgery.

DESIGN

A randomised controlled study.

SETTING

A single-centre trial from March 2018 to June 2018.

PATIENTS

Forty-four adult patients undergoing laparoscopic gynaecological surgery with anticipated duration of surgery more than 2 h.

INTERVENTION

PEEP set according to Poeso measurement (intervention group) versus PEEP constantly set at 5 cmH2O (control group).

MAIN OUTCOME MEASURES

Gas exchange and respiratory mechanics after induction and intubation (T0) and at 15 and 60 min after initiation of pneumoperitoneum (T1 and T2, respectively).

RESULTS

PEEP during pneumoperitoneum was significantly higher in the intervention group than in the control group (T1, 12.5 ± 1.9 vs. 5.0 ± 0.0 cmH2O and T2, 12.4 ± 1.9 vs. 5.0 ± 0.0 cmH2O, both P < 0.001). Partial pressures of oxygen decreased significantly from baseline during pneumoperitoneum in the control group but not in the intervention group. Nevertheless, the changes in partial pressures of oxygen did not differ between groups. Compliance of the respiratory system (CRS) significantly decreased and driving pressure significantly increased during pneumoperitoneum in both groups. However, the changes in CRS and driving pressure were significantly less in the intervention group. Transpulmonary pressure during expiration was maintained in the intervention group while it decreased significantly in the control group.

CONCLUSION

PEEP setting guided by Poeso measurement showed no beneficial effects in terms of oxygenation but respiratory mechanics were better during laparoscopic gynaecological surgery.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03256396.

Perioperative interventions for prevention of postoperative pulmonary complications: systematic review and meta-analysis

OBJECTIVE

To identify, appraise, and synthesise the best available evidence on the efficacy of perioperative interventions to reduce postoperative pulmonary complications (PPCs) in adult patients undergoing non-cardiac surgery.

DESIGN

Systematic review and meta-analysis of randomised controlled trials.

DATA SOURCES

Medline, Embase, CINHAL, and CENTRAL from January 1990 to December 2017.

ELIGIBILITY CRITERIA

Randomised controlled trials investigating short term, protocolised medical interventions conducted before, during, or after non-cardiac surgery were included. Trials with clinical diagnostic criteria for PPC outcomes were included. Studies of surgical technique or physiological or biochemical outcomes were excluded.

DATA EXTRACTION AND SYNTHESIS

Reviewers independently identified studies, extracted data, and assessed the quality of evidence. Meta-analyses were conducted to calculate risk ratios with 95% confidence intervals. Quality of evidence was summarised in accordance with GRADE methods. The primary outcome was the incidence of PPCs. Secondary outcomes were respiratory infection, atelectasis, length of hospital stay, and mortality. Trial sequential analysis was used to investigate the reliability and conclusiveness of available evidence. Adverse effects of interventions were not measured or compared.

RESULTS

117 trials enrolled 21 940 participants, investigating 11 categories of intervention. 95 randomised controlled trials enrolling 18 062 participants were included in meta-analysis; 22 trials were excluded from meta-analysis because the interventions were not sufficiently similar to be pooled. No high quality evidence was found for interventions to reduce the primary outcome (incidence of PPCs). Seven interventions had low or moderate quality evidence with confidence intervals indicating a probable reduction in PPCs: enhanced recovery pathways (risk ratio 0.35, 95% confidence interval 0.21 to 0.58), prophylactic mucolytics (0.40, 0.23 to 0.67), postoperative continuous positive airway pressure ventilation (0.49, 0.24 to 0.99), lung protective intraoperative ventilation (0.52, 0.30 to 0.88), prophylactic respiratory physiotherapy (0.55, 0.32 to 0.93), epidural analgesia (0.77, 0.65 to 0.92), and goal directed haemodynamic therapy (0.87, 0.77 to 0.98). Moderate quality evidence showed no benefit for incentive spirometry in preventing PPCs. Trial sequential analysis adjustment confidently supported a relative risk reduction of 25% in PPCs for prophylactic respiratory physiotherapy, epidural analgesia, enhanced recovery pathways, and goal directed haemodynamic therapies. Insufficient data were available to support or refute equivalent relative risk reductions for other interventions.

CONCLUSIONS

Predominantly low quality evidence favours multiple perioperative PPC reduction strategies. Clinicians may choose to reassess their perioperative care pathways, but the results indicate that new trials with a low risk of bias are needed to obtain conclusive evidence of efficacy for many of these interventions.

STUDY REGISTRATION

Prospero CRD42016035662.

The Effect of sevoflurane, desflurane and propofol on respiratory mechanics and integrated pulmonary index scores in laparoscopic sleeve gastrectomy. A randomized trial

Objectives:

To compare the effects of sevoflurane, desflurane, and propofol on respiratory mechanics, and integrated pulmonary index (IPI) scores in patients undergoing laparoscopic sleeve gastrectomy.

Methods:

A total of 60 patients with a body mass index of ≥40 kg/m², who underwent laparoscopic sleeve gastrectomy between September 2015 and September 2016 at Fatih Sultan Mehmet Health Application and Research Center, Istanbul, Turkey were included in this randomized prospective study. After induction, anesthesia was maintained by sevoflurane in group S, desflurane in group D, and propofol in group P. Peak inspiratory pressure (PIP), plateau pressure (P_plateau), compliance (Cdyn), respiratory resistance (Rrs), and IPI values were recorded. Mann-Whitney U, Kruskal-Wallis, Dunn’s, Friedman, and Fisher-Freeman-Halton tests were performed for statistical analysis. A p value of <0.05 was considered statistically significant.

Results:

A significant increase was found in PIP in group S (T₁: 25; T₂: 27 cmH₂O), and group D (T₁: 25; T₂: 29,5 cmH₂O) during pneumoperitoneum. Dynamic compliance decreased in all groups during pneumoperitoneum. In group S, the decrease in Cdyn was also statistically significant after pneumoperitoneum (T₁: 43.65; T₅: 41.25 ml/cmH₂O). Comparison between groups the values of PIP, P_plateau, Cdyn, Rrs, and IPI were similar.

Conclusion:

In morbidly obese patients, sevoflurane, desflurane, and propofol are similar in terms of the intraoperative respiratory mechanics, and perioperative respiratory parameters provided with IPI.

Effects of intraoperative PEEP on postoperative pulmonary complications in high-risk patients undergoing laparoscopic abdominal surgery: study protocol for a randomised controlled trial

INTRODUCTION

Postoperative pulmonary complications (PPCs), strongly associated with higher mortality risk, can develop in up to 58% of patients undergoing abdominal surgery. More and more evidence shows that the use of a lung-protective ventilation strategy has a lung protection effect in patients undergoing abdominal surgery, however, the role of positive end-expiratory pressure (PEEP) during the intraoperative period in preventing PPCs for laparoscopic surgery is not clearly defined.

METHODS AND ANALYSIS

A total of 208 patients with a high risk of PPC, undergoing laparoscopic abdominal surgery, will be enrolled and randomised into a standard PEEP (6-8 cm H₂O) group and a low PEEP (≤2 cm H₂O) group. Both groups will receive a fraction of inspired oxygen of 0.50 and a tidal volume of 8 mL/kg ideal body weight (IBW). Standard perioperative fluid management and analgesic treatments are applied in both groups. The primary end point is PPC within 7 days after surgery. Secondary end points are the modified Clinical Pulmonary Infection Score, postoperative extrapulmonary complications, postoperative surgical complications, intensive care unit length of stay, hospital length of stay, 30-day mortality.

ETHICS AND DISSEMINATION

The study was approved by the Ethics Committee of Zhejiang Provincial People's Hospital (People's Hospital of Hangzhou Medicine College) (registration number KY2018026) on 22 October 2018. The first participant was recruited on 15 April 2019 and the estimated completion date of the study is October 2021. The results of this trial will be submitted to a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

http://www.chictr.org.cn, ID: ChiCTR1800019865. Registered on 2 December 2018; preresults.

Positive End-Expiratory Pressure During Anesthesia for Prevention of Postoperative Pulmonary Complications: A Meta-analysis With Trial Sequential Analysis of Randomized Controlled Trials

BACKGROUND

Whether intraoperative positive end-expiratory pressure (PEEP) can reduce the risk of postoperative pulmonary complications remains controversial. We performed a systematic review of currently available literature to investigate whether intraoperative PEEP decreases pulmonary complications in anesthetized patients undergoing surgery.

METHODS

We searched PubMed, Embase, and the Cochrane Library to identify randomized controlled trials (RCTs) that compared intraoperative PEEP versus zero PEEP (ZEEP) for postoperative pulmonary complications in adults. The prespecified primary outcome was postoperative pulmonary atelectasis.

RESULTS

Fourteen RCTs enrolling 1238 patients met the inclusion criteria. Meta-analysis using a random-effects model showed a decrease in postoperative atelectasis (relative risk [RR], 0.51; 95% confidence interval [CI], 0.35-0.76; trial sequential analyses [TSA]-adjusted CI, 0.10-2.55) and postoperative pneumonia (RR, 0.48; 95% CI, 0.27-0.84; TSA-adjusted CI, 0.05-4.86) in patients receiving PEEP ventilation. However, TSA showed that the cumulative Z-curve of 2 outcomes crossed the conventional boundary but did not cross the trial sequential monitoring boundary, indicating a possible false-positive result. We observed no effect of PEEP versus ZEEP ventilation on postoperative mortality (RR, 1.78; 95% CI, 0.55-5.70).

CONCLUSIONS

The evidence that intraoperative PEEP reduces postoperative pulmonary complications is suggestive but too unreliable to allow definitive conclusions to be drawn.

The tidal volume challenge improves the reliability of dynamic preload indices during robot-assisted laparoscopic surgery in the Trendelenburg position with lung-protective ventilation

Background

The reliability of pulse pressure variation (PPV) and stroke volume variation (SVV) is controversial under pneumoperitoneum. In addition, the usefulness of these indices is being called into question with the increasing adoption of lung-protective ventilation using low tidal volume (V_T) in surgical patients. A recent study indicated that changes in PPV or SVV obtained by transiently increasing V_T (V_T challenge) accurately predicted fluid responsiveness even in critically ill patients receiving low V_T. We evaluated whether the changes in PPV and SVV induced by a V_T challenge predicted fluid responsiveness during pneumoperitoneum.

Methods

We performed an interventional prospective study in patients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position under lung-protective ventilation. PPV, SVV, and the stroke volume index (SVI) were measured at a V_T of 6 mL/kg and 3 min after increasing the V_T to 8 mL/kg. The V_T was reduced to 6 mL/kg, and measurements were performed before and 5 min after volume expansion (infusing 6% hydroxyethyl starch 6 ml/kg over 10 min). Fluid responsiveness was defined as ≥15% increase in the SVI.

Results

Twenty-four of the 38 patients enrolled in the study were responders. In the receiver operating characteristic curve analysis, an increase in PPV > 1% after the V_T challenge showed excellent predictive capability for fluid responsiveness, with an area under the curve (AUC) of 0.95 [95% confidence interval (CI), 0.83–0.99, P < 0.0001; sensitivity 92%, specificity 86%]. An increase in SVV > 2% after the V_T challenge predicted fluid responsiveness, but showed only fair predictive capability, with an AUC of 0.76 (95% CI, 0.60–0.89, P < 0.0006; sensitivity 46%, specificity 100%). The augmented values of PPV and SVV following V_T challenge also showed the improved predictability of fluid responsiveness compared to PPV and SVV values (as measured by V_T) of 6 ml/kg.

Conclusions

The change in PPV following the V_T challenge has excellent reliability in predicting fluid responsiveness in our surgical population. The change in SVV and augmented values of PPV and SVV following this test are also reliable.

Trial registration

This trial was registered with Clinicaltrials.gov, NCT03467711, 10th March 2018.

Exploring the intraoperative lung protective ventilation of different positive end-expiratory pressure levels during abdominal laparoscopic surgery with Trendelenburg position

Background

The intraoperative lung protective effect of mechanical ventilation of different positive end-expiratory pressure (PEEP) levels on patients undergoing abdominal laparoscopic surgery with the steep Trendelenburg position remains undefined. The purpose of the study was to explore the optimal PEEP.

Methods

Sixty patients scheduled for abdominal laparoscopic surgery were randomized to four groups including: PEEP 0, 4, 8 and 12 cmH₂O. The pulmonary dynamic compliance (Cdyn), dead space to tidal volume ratio (VD/VT), and intrapulmonary shunt ratio (QS/QT) were measured after anesthesia induction (T₀), 5 min after pneumoperitoneum (PNP) with position change (T₁), 30 (T₂) and 60 min (T₃) after PEEP, and end of surgery (T₄).

Results

Cdyn increased when different levels of PEEP (including the 4, 8, and 12 cmH₂O) were used vs. no PEEP (P<0.05). The VD/VT in PEEP 8 and 12 cmH₂O were significantly improved than no PEEP (P<0.05). Meanwhile, the QS/QT in PEEP 12 cmH₂O was higher than others during the procedures.

Conclusions

A moderate PEEP level (8 cmH₂O) with low tidal volume was sufficient to improve Cdyn and to decrease VD/VT without increasing QS/QT, which was suggested to be a good choice of intraoperative lung protective ventilation during abdominal laparoscopic surgery with Trendelenburg position.

Effects of intraoperative PEEP on postoperative pulmonary complications in patients undergoing robot-assisted laparoscopic radical resection for bladder cancer or prostate cancer: study protocol for a randomized controlled trial

Background

There are increasing studies showing that the use of a lung-protective ventilation strategy has a lung protection effect in patients undergoing abdominal surgery; however, the appropriate positive end-expiratory pressure (PEEP) has not yet defined. Adopting a suitable PEEP may prevent postoperative pulmonary complications. Robot-assisted laparoscopic surgery is the newest and most minimally invasive treatment for bladder cancer or prostate cancer. It is also necessary to consider the effects of Trendelenburg position with pneumoperitoneum on airway pressure and pulmonary function. The role of PEEP during the intraoperative period in preventing postoperative pulmonary complications for robot-assisted laparoscopic surgery is not clearly defined.

Methods/design

A total of 208 patients undergoing robot-assisted laparoscopic radical resection for bladder cancer or prostate cancer will be enrolled and then randomly assigned to a standard PEEP (6–8 cm H₂O) group and a low PEEP (≤2 cm H₂O) group. Both groups will receive an inspired oxygen fraction of 0.50 and a tidal volume of 8 mL/kg ideal body weight. Standard perioperative fluid management standardization and analgesic treatments will be applied in both groups. The primary endpoint is postoperative pulmonary complications within 7 days after surgery. Secondary endpoints are the modified clinical pulmonary infection score, postoperative extrapulmonary complications, postoperative surgical complications, intensive care unit length of stay, hospital length of stay, and 30-day mortality.

Discussion

This trial aimed to assess the effects of low tidal volumes combined with intraoperative PEEP ventilation strategy on postoperative pulmonary complications in patients undergoing robot-assisted laparoscopic radical resection for bladder cancer or prostate cancer.

Trial registration

ID: ChiCTR1800019867. Registered on December 2, 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3363-y) contains supplementary material, which is available to authorized users.

Perioperative lung protective ventilation

Perioperative lung injury is a major source of postoperative morbidity, excess healthcare use, and avoidable mortality. Many potential inciting factors can lead to this condition, including intraoperative ventilator induced lung injury. Questions exist as to whether protective ventilation strategies used in the intensive care unit for patients with acute respiratory distress syndrome are equally beneficial for surgical patients, most of whom do not present with any pre-existing lung pathology. Studied both individually and in combination as a package of intraoperative lung protective ventilation, the use of low tidal volumes, moderate positive end expiratory pressure, and recruitment maneuvers have been shown to improve oxygenation and pulmonary physiology and to reduce postoperative pulmonary complications in at risk patient groups. Further work is needed to define the potential contributions of alternative ventilator strategies, limiting excessive intraoperative oxygen supplementation, use of non-invasive techniques in the postoperative period, and personalized mechanical ventilation. Although the weight of evidence strongly suggests a role for lung protective ventilation in moderate risk patient groups, definitive evidence of its benefit for the general surgical population does not exist. However, given the shift in understanding of what is needed for adequate oxygenation and ventilation under anesthesia, the largely historical arguments against the use of intraoperative lung protective ventilation may soon be outdated, on the basis of its expanding track record of safety and efficacy in multiple settings.

Intraoperative use of low volume ventilation to decrease postoperative mortality, mechanical ventilation, lengths of stay and lung injury in adults without acute lung injury

BACKGROUND

Since the 2000s, there has been a trend towards decreasing tidal volumes for positive pressure ventilation during surgery. This an update of a review first published in 2015, trying to determine if lower tidal volumes are beneficial or harmful for patients.

OBJECTIVES

To assess the benefit of intraoperative use of low tidal volume ventilation (less than 10 mL/kg of predicted body weight) compared with high tidal volumes (10 mL/kg or greater) to decrease postoperative complications in adults without acute lung injury.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (OvidSP) (from 1946 to 19 May 2017), Embase (OvidSP) (from 1974 to 19 May 2017) and six trial registries. We screened the reference lists of all studies retained and of recent meta-analysis related to the topic during data extraction. We also screened conference proceedings of anaesthesiology societies, published in two major anaesthesiology journals. The search was rerun 3 January 2018.

SELECTION CRITERIA

We included all parallel randomized controlled trials (RCTs) that evaluated the effect of low tidal volumes (defined as less than 10 mL/kg) on any of our selected outcomes in adults undergoing any type of surgery. We did not retain studies with participants requiring one-lung ventilation.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the quality of the retained studies with the Cochrane 'Risk of bias' tool. We analysed data with both fixed-effect (I² statistic less than 25%) or random-effects (I² statistic greater than 25%) models based on the degree of heterogeneity. When there was an effect, we calculated a number needed to treat for an additional beneficial outcome (NNTB) using the odds ratio. When there was no effect, we calculated the optimum information size.

MAIN RESULTS

We included seven new RCTs (536 participants) in the update.In total, we included 19 studies in the review (776 participants in the low tidal volume group and 772 in the high volume group). There are four studies awaiting classification and three are ongoing. All included studies were at some risk of bias. Participants were scheduled for abdominal surgery, heart surgery, pulmonary thromboendarterectomy, spinal surgery and knee surgery. Low tidal volumes used in the studies varied from 6 mL/kg to 8.1 mL/kg while high tidal volumes varied from 10 mL/kg to 12 mL/kg.Based on 12 studies including 1207 participants, the effects of low volume ventilation on 0- to 30-day mortality were uncertain (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.42 to 1.53; I² = 0%; low-quality evidence). Based on seven studies including 778 participants, lower tidal volumes probably reduced postoperative pneumonia (RR 0.45, 95% CI 0.25 to 0.82; I² = 0%; moderate-quality evidence; NNTB 24, 95% CI 16 to 160), and it probably reduced the need for non-invasive postoperative ventilatory support based on three studies including 506 participants (RR 0.31, 95% CI 0.15 to 0.64; moderate-quality evidence; NNTB 13, 95% CI 11 to 24). Based on 11 studies including 957 participants, low tidal volumes during surgery probably decreased the need for postoperative invasive ventilatory support (RR 0.33, 95% CI 0.14 to 0.77; I² = 0%; NNTB 39, 95% CI 30 to 166; moderate-quality evidence). Based on five studies including 898 participants, there may be little or no difference in the intensive care unit length of stay (standardized mean difference (SMD) -0.06, 95% CI -0.22 to 0.10; I² = 33%; low-quality evidence). Based on 14 studies including 1297 participants, low tidal volumes may have reduced hospital length of stay by about 0.8 days (SMD -0.15, 95% CI -0.29 to 0.00; I² = 27%; low-quality evidence). Based on five studies including 708 participants, the effects of low volume ventilation on barotrauma (pneumothorax) were uncertain (RR 1.77, 95% CI 0.52 to 5.99; I² = 0%; very low-quality evidence).

AUTHORS' CONCLUSIONS

We found moderate-quality evidence that low tidal volumes (defined as less than 10 mL/kg) decreases pneumonia and the need for postoperative ventilatory support (invasive and non-invasive). We found no difference in the risk of barotrauma (pneumothorax), but the number of participants included does not allow us to make definitive statement on this. The four studies in 'Studies awaiting classification' may alter the conclusions of the review once assessed.

Joint consensus on abdominal robotic surgery and anesthesia from a task force of the SIAARTI and SIC

Minimally invasive surgical procedures have revolutionized the world of surgery in the past decades. While laparoscopy, the first minimally invasive surgical technique to be developed, is widely used and has been addressed by several guidelines and recommendations, the implementation of robotic-assisted surgery is still hindered by the lack of consensus documents that support healthcare professionals in the management of this novel surgical procedure. Here we summarize the available evidence and provide expert opinion aimed at improving the implementation and resolution of issues derived from robotic abdominal surgery procedures. A joint task force of Italian surgeons, anesthesiologists and clinical epidemiologists reviewed the available evidence on robotic abdominal surgery. Recommendations were graded according to the strength of evidence. Statements and recommendations are provided for general issues regarding robotic abdominal surgery, operating theatre organization, preoperative patient assessment and preparation, intraoperative management, and postoperative procedures and discharge. The consensus document provides evidence-based recommendations and expert statements aimed at improving the implementation and management of robotic abdominal surgery.

Application of intraoperative lung-protective ventilation varies in accordance with the knowledge of anaesthesiologists: a single-Centre questionnaire study and a retrospective observational study

Background

The benefits of lung-protective ventilation (LPV) with a low tidal volume (6 mL/kg of ideal body weight [IBW]), limited plateau pressure (< 28–30 cm H₂O), and appropriate positive end-expiratory pressure (PEEP) in patients with acute respiratory distress syndrome have become apparent and it is now widely adopted in intensive care units. Recently evidence for LPV in general anaesthesia has been accumulated, but it is not yet generally applied by anaesthesiologists in the operating room.

Methods

This study investigated the perception about intraoperative LPV among 82 anaesthesiologists through a questionnaire survey and identified the differences in ventilator settings according to recognition of lung-protective ventilation. Furthermore, we investigated the changes in the trend for using this form of ventilation during general anaesthesia in the past 10 years.

Results

Anaesthesiologists who had received training in LPV were more knowledgeable about this approach. Anaesthesiologists with knowledge of the concept behind LPV strategies applied a lower tidal volume (median (IQR [range]), 8.2 (8.0–9.2 [7.1–10.3]) vs. 9.2 (9.1–10.1 [7.6–10.1]) mL/kg; p = 0.033) and used PEEP more frequently (69/72 [95.8%] vs. 5/8 [62.5%]; p = 0.012; odds ratio, 13.8 [2.19–86.9]) for laparoscopic surgery than did those without such knowledge. Anaesthesiologists who were able to answer a question related to LPV correctly (respondents who chose ‘height’ to a multiple choice question asking what variables should be considered most important in the initial setting of tidal volume) applied a lower tidal volume in cases of laparoscopic surgery and obese patients. There was an increase in the number of patients receiving LPV (V_T < 10 mL/kgIBW and PEEP ≥5 cm H₂O) between 2004 and 2014 (0/818 [0.0%] vs. 280/818 [34.2%]; p <  0.001).

Conclusions

Our study suggests that the knowledge of LPV is directly related to its implementation, and can explain the increase in LPV use in general anaesthesia. Further studies should assess the impact of using intraoperative LPV on clinical outcomes and should determine the efficacy of education on intraoperative LPV implementation.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0495-7) contains supplementary material, which is available to authorized users.

Low Tidal Volume Positive End-Expiratory Pressure versus High Tidal Volume Zero-Positive End-Expiratory Pressure and Postoperative Pulmonary Functions in Robot-Assisted Laparoscopic Radical Prostatectomy

OBJECTIVE

The aim was to compare the effects of low tidal volume (VT) and moderate positive end-expiratory pressure (PEEP) with high VT and zero end-expiratory pressure (ZEEP) on postoperative pulmonary functions and oxygenation in patients undergoing robot-assisted laparoscopic radical prostatectomy.

SUBJECTS AND METHODS

Forty-four patients were randomized into low VT-PEEP and high VT-ZEEP groups. The patients were ventilated with a VT of 6 mL/kg and 8 cm H2O PEEP in the low VT-PEEP group and a VT of 10 mL/kg and 0 cm H2O PEEP in the high VT-ZEEP group. Preoperative and postoperative spirometric measurements were done and chest X-rays were evaluated using the radiological atelectasis score (RAS). p < 0.05 was considered statistically significant.

RESULTS

The intraoperative and postoperative arterial partial pressure of oxygen and arterial oxygen saturation values were significantly higher in the low VT-PEEP group than in the high VT-ZEEP group. At all times, the arterial-to-alveolar oxygenation gradients were significantly lower in the low VT-PEEP group than in the high VT-ZEEP group. Preoperative RAS were similar in both groups, but the postoperative RAS was significantly lower in the low VT-PEEP group (p < 0.001). Forced vital capacity, forced expiratory volume in 1 s, and peak expiratory flow rate recorded postoperatively were significantly lower in the high VT-ZEEP group (p < 0.001).

CONCLUSIONS

Postoperative pulmonary functions were less impaired in patients ventilated with a VT of 6 mL/kg and 8 cm H2O PEEP than in patients ventilated with a VT of 10 mL/kg and ZEEP.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

Pneumoperitoneum deteriorates intratidal respiratory system mechanics: an observational study in lung-healthy patients

BACKGROUND

Pneumoperitoneum during laparoscopic surgery leads to atelectasis and impairment of oxygenation. Positive end-expiratory pressure (PEEP) is supposed to counteract atelectasis. We hypothesized that the derecruiting effects of pneumoperitoneum would deteriorate the intratidal compliance profile in patients undergoing laparoscopic surgery.

METHODS

In 30 adult patients scheduled for surgery with pneumoperitoneum, respiratory variables were measured during mechanical ventilation. We calculated the dynamic compliance of the respiratory system (C _RS) and the intratidal volume-dependent C _RS curve using the gliding-SLICE method. The C _RS curve was then classified in terms of indicating intratidal recruitment/derecruitment (increasing profile) and overdistension (decreasing profile). During the surgical interventions, the PEEP level was maintained nearly constant at 7 cm H₂O. Data are expressed as mean [confidence interval].

RESULTS

Baseline C _RS was 60 [54-67] mL cm H₂O^-1. Application of pneumoperitoneum decreased C _RS to 40 [37-43] mL cm H₂O^-1 which partially recovered to 54 [50-59] mL cm H₂O^-1 (P < 0.001) after removal but remained below the value measured before pneumoperitoneum (P < 0.001). Baseline compliance profiles indicated intratidal recruitment/derecruitment in 48 % patients. After induction of pneumoperitoneum, intratidal recruitment/derecruitment was indicated in 93 % patients (P < 0.01), and after removal intratidal recruitment/derecruitment was indicated in 59 % patients. Compliance profiles showing overdistension were not observed.

CONCLUSIONS

Analyses of the intratidal compliance profiles reveal that pneumoperitoneum during laparoscopic surgery causes intratidal recruitment/derecruitment which partly persists after its removal. The analysis of the intratidal volume-dependent C _RS profiles could be used to guide intraoperative PEEP adjustments during elevated intraabdominal pressure.