Lung-protective ventilation for the surgical patient: international expert panel-based consensus recommendations

Comparative effects of variable versus conventional volume-controlled one-lung ventilation on gas exchange and respiratory system mechanics in thoracic surgery patients: A randomized controlled clinical trial

BACKGROUND

Mechanical ventilation with variable tidal volumes (V-VCV) has the potential to improve lung function during general anesthesia. We tested the hypothesis that V-VCV compared to conventional volume-controlled ventilation (C-VCV) would improve intraoperative arterial oxygenation and respiratory system mechanics in patients undergoing thoracic surgery under one-lung ventilation (OLV).

METHODS

Patients were randomized to V-VCV (n = 39) or C-VCV (n = 39). During OLV tidal volume of 5 mL/kg predicted body weight (PBW) was used. Both groups were ventilated with a positive end-expiratory pressure (PEEP) of 5 cm H2O, inspiration to expiration ratio (I:E) of 1:1 (during OLV) and 1:2 during two-lung ventilation, the respiratory rate (RR) titrated to arterial pH, inspiratory peak-pressure ≤ 40 cm H2O and an inspiratory oxygen fraction of 1.0.

RESULTS

Seventy-five out of 78 Patients completed the trial and were analyzed (dropouts were excluded). The partial pressure of arterial oxygen (PaO2) 20 min after the start of OLV did not differ among groups (V-VCV: 25.8 ± 14.6 kPa vs C-VCV: 27.2 ± 15.3 kPa; mean difference [95% CI]: 1.3 [-8.2, 5.5], P = 0.700). Furthermore, intraoperative gas exchange, intraoperative adverse events, need for rescue maneuvers due to desaturation and hypercapnia, incidence of postoperative pulmonary and extra-pulmonary complications, and hospital free days at day 30 after surgery did not differ between groups.

CONCLUSIONS

In thoracic surgery patients under OLV, V-VCV did not improve oxygenation or respiratory system mechanics compared to C-VCV. Ethical Committee: EK 420092019.

TRIAL REGISTRATION

at the German Clinical Trials Register: DRKS00022202 (16.06.2020).

Weaning from mechanical ventilation in the operating room: a systematic review

BACKGROUND

Postoperative pulmonary complications (PPCs) are associated with postoperative mortality and prolonged hospital stay. Although intraoperative mechanical ventilation (MV) is a risk factor for PPCs, strategies addressing weaning from MV are understudied. In this systematic review, we evaluated weaning strategies and their effects on postoperative pulmonary outcomes.

METHODS

Our protocol was registered on PROSPERO (CRD42022379145). Eligible studies included randomised controlled trials and observational studies of adults weaned from MV in the operating room. Primary outcomes included atelectasis and oxygenation; secondary outcomes included lung volume changes and PPCs. Risk of bias was assessed using the Cochrane Risk of Bias (RoB2) tool, and quality of evidence with the GRADE framework.

RESULTS

Screening identified 14 randomised controlled trials including 1719 patients; seven studies were limited to the weaning phase and seven included interventions not restricted to the weaning phase. Strategies combining pressure support ventilation (PSV) with positive end-expiratory pressure (PEEP) and low fraction of inspired oxygen (FiO2) improved atelectasis, oxygenation, and lung volumes. Low FiO2 improved atelectasis and oxygenation but might not improve lung volumes. A fixed-PEEP strategy led to no improvement in oxygenation or atelectasis; however, individualised PEEP with low FiO2 improved oxygenation and might be associated with reduced PPCs. Half of included studies are of moderate or high risk of bias; the overall quality of evidence is low.

CONCLUSIONS

There is limited research evaluating weaning from intraoperative MV. Based on low-quality evidence, PSV, individualised PEEP, and low FiO2 may be associated with reduced postoperative pulmonary outcomes.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42022379145).

Determination of optimal positive end-expiratory pressure using electrical impedance tomography in infants under general anesthesia: Comparison between supine and prone positions

AIMS

This study determined the optimal positive end-expiratory pressure levels in infants in supine and prone positions under general anesthesia using electrical impedance tomography (EIT).

METHODS

This prospective observational single-centre study included infants scheduled for surgery in the prone position. An electrical impedance tomography sensor was applied after inducing general anesthesia. The optimal positive end-expiratory pressure in the supine position was determined in a decremental trial based on EIT and compliance. Subsequently, the patient's position was changed to prone. Electrical impedance tomography parameters, including global inhomogeneity index, regional ventilation delay, opening pressure, the centre of ventilation, and pendelluft volume, were continuously obtained up to 1 h after prone positioning. The optimal positive end-expiratory pressure in the prone position was similarly determined.

RESULTS

Data from 30 infants were analyzed. The mean value of electrical impedance tomography-based optimal positive end-expiratory pressure in the prone position was significantly higher than that in the supine position [10.9 (1.6) cmH2O and 6.1 (0.9) cmH2O, respectively (p < .001)]. Significant differences were observed between electrical impedance tomography- and compliance-based optimal positive end-expiratory pressure. Peak and mean airway, plateau, and driving pressures increased 1 h after prone positioning compared with those in the supine position. In addition, the centre of ventilation for balance in ventilation between the ventral and dorsal regions improved.

CONCLUSION

The prone position required higher positive end-expiratory pressure than the supine position in mechanically ventilated infants under general anesthesia. EIT is a promising tool to find the optimal positive end-expiratory pressure, which needs to be individualized.

Risk factors for anastomotic leakage after low anterior resection for obese patients with rectal cancer

PURPOSE

We aimed to analyze the risk factors for anastomotic leakage (AL) after low anterior resection (LAR) in obese patients (body mass index [BMI] ≥ 25 kg/m2) with rectal cancer.

METHODS

Data were collected from four hundred two obese patients who underwent LAR for rectal cancer in 51 institutions.

RESULTS

Forty-six (11.4%) patients had clinical AL. The median BMI (27 kg/m2) did not differ between the AL and non-AL groups. In the AL group, comorbid respiratory disease was more common (p = 0.025), and the median tumor size was larger (p = 0.002). The incidence of AL was 11.5% in the open surgery subgroup and 11.4% in the laparoscopic surgery subgroup. Among the patients who underwent open surgery, the AL group showed a male predominance (p = 0.04) in the univariate analysis, but it was not statistically significant in the multivariate analysis. Among the patients who underwent laparoscopic surgery, the AL group included a higher proportion of patients with comorbid respiratory disease (p = 0.003) and larger tumors (p = 0.007).

CONCLUSION

Comorbid respiratory disease and tumor size were risk factors for AL in obese patients with rectal cancer. Careful perioperative respiratory management and appropriate selection of surgical procedures are required for obese rectal cancer patients with respiratory diseases.

The effects of laryngeal mask versus endotracheal tube on atelectasis after general anesthesia induction assessed by lung ultrasound: A randomized controlled trial

STUDY OBJECTIVE

This study aims to evaluate the impact of Supreme™ laryngeal masks versus endotracheal tubes on atelectasis during general anesthesia using lung ultrasound (LUS), and provide evidence for respiratory management.

DESIGN

A single-center, double-blind, randomized controlled trial was conducted.

SETTING

The study was conducted in both the operating room and the post-anesthesia care unit, with follow-up assessments performed in the ward.

PATIENTS

Enrollment included 180 cases undergoing non-laparoscopic surgeries in gynecology, urology, and orthopedic limb surgeries.

INTERVENTIONS

Patients were randomly assigned 1:1 to the endotracheal intubation or laryngeal mask group.

MEASUREMENTS

LUS scores were recorded across 12 lung regions at baseline, 15 min after airway establishment, at the end of surgery, and 30 min following airway removal. Outcome measures encompassed the oxygenation index, dynamic lung compliance, incidence of postoperative pulmonary complications, throat pain, and other postoperative complications assessed at 24 and 48 h postoperatively. The primary outcome focused on the LUS score in all 12 lung regions at 15 min after airway establishment.

MAIN RESULTS

Intention-to-treat analysis of 177 subjects revealed endotracheal intubation led to significantly higher LUS scores at 15 min {P < 0.001, mean difference 4.15 ± 0.60, 95% CI [2.97, 5.33]}, end of surgery (P < 0.001, mean difference 3.37 ± 0.68, 95% CI [2.02, 4.72]), and 30 min post-removal (P < 0.001, mean difference 2.63 ± 0.48, 95% CI [1.68, 3.58]). No major complications occurred in the two groups.

CONCLUSIONS

Compared to endotracheal intubation, laryngeal masks effectively reduce atelectasis formation and progression in gynecological, urological non-laparoscopic, and orthopedic limb surgeries. However, caution is warranted when generalizing these findings to surgeries with a higher risk of laryngeal mask leakage or obese patients. Additionally, the efficacy of laryngeal masks in reducing postoperative atelectasis remains uncertain when comprehensive monitoring of muscle relaxation and reversal therapy is employed.

Effects of starting one lung ventilation and applying individualized PEEP right after patients are placed in lateral decubitus position on intraoperative oxygenation for patients undergoing thoracoscopic pulmonary lobectomy: study protocol for a randomized controlled trial

BACKGROUND

For patients receiving one lung ventilation in thoracic surgery, numerous studies have proved the superiority of lung protective ventilation of low tidal volume combined with recruitment maneuvers (RM) and individualized PEEP. However, RM may lead to overinflation which aggravates lung injury and intrapulmonary shunt. According to CT results, atelectasis usually forms in gravity dependent lung regions, regardless of body position. So, during anesthesia induction in supine position, atelectasis usually forms in the dorsal parts of lungs, however, when patients are turned into lateral decubitus position, collapsed lung tissue in the dorsal parts would reexpand, while atelectasis would slowly reappear in the lower flank of the lung. We hypothesize that applying sufficient PEEP without RM before the formation of atelectasis in the lower flank of the lung may beas effective to prevent atelectasis and thus improve oxygenation as applying PEEP with RM.

METHODS

A total of 84 patients scheduled for elective pulmonary lobe resection necessitating one lung ventilation will be recruited and randomized totwo parallel groups. For all patients, one lung ventilation is initiated the right after patients are turned into lateral decubitus position. For patients in the study group, individualized PEEP titration is started the moment one lung ventilation is started, while patients in the control group will receive a recruitment maneuver followed by individualized PEEP titration after initiation of one lung ventilation. The primary endpoint will be oxygenation index measured at T4. Secondary endpoints will include intrapulmonary shunt, respiratory mechanics, PPCs, and hemodynamic indicators.

DISCUSSION

Numerous previous studies compared the effects of individualized PEEP applied alone with that applied in combination with RM on oxygenation index, PPCs, intrapulmonary shunt and respiratory mechanics after atelectasis was formed in patients receiving one lung ventilation during thoracoscopic surgery. In this study, we will apply individualized PEEP before the formation of atelectasis while not performing RM in patients allocated to the study group, and then we're going to observe its effects on the aspects mentioned above. The results of this trial will provide a ventilation strategy that may be conductive to improving intraoperative oxygenation and avoiding the detrimental effects of RM for patients receiving one lung ventilation.

TRIAL REGISTRATION

www.Chictr.org.cn ChiCTR2400080682. Registered on February 5, 2024.

Effects of individualised lung-protective ventilation with lung dynamic compliance-guided positive end-expiratory pressure titration on postoperative pulmonary complications of paediatric video-assisted thoracoscopic surgery: protocol for a randomised controlled trial

INTRODUCTION

Lung-protective ventilation strategies (LPVS) for one-lung ventilation (OLV) in paediatric patients pose greater challenges than in adults. Optimising LPVS for paediatric OLV to mitigate postoperative pulmonary complications (PPCs) has emerged as a current research focal point. However, there remains a divergence of opinions concerning the individualised setting and application of positive end-expiratory pressure (PEEP). Lung dynamic compliance (Cdyn) can serve as a reflection of the lung's physiological state in children during OLV and is a readily obtainable parameter. This study protocol is formulated to assess the effectiveness of Cdyn-guided PEEP titration on PPCs during paediatric OLV.

METHODS AND ANALYSIS

This study constitutes a single-centre, prospective, double-blind, randomised controlled trial. The trial aims to recruit 60 paediatric patients scheduled for video-assisted thoracoscopic surgery. These eligible patients will be randomly assigned to either the Cdyn-guided PEEP group or the conventional PEEP group during general anaesthesia for OLV. The primary outcome will involve assessing the incidence of PPCs at 7 days after surgery. Secondary outcomes will encompass the evaluation of the modified lung ultrasound score following surgery, as well as monitoring the oxygenation index, driving pressure and Cdyn during mechanical ventilation. Data collection will be performed by investigators who are kept blinded to the interventions.

ETHICS AND DISSEMINATION

The Clinical Trial Ethics Committee at Shenzhen Children's Hospital has conferred ethical approvals for this trial (approval number: 2022076). Results from this trial will be disseminated in peer-reviewed journals and presented at professional symposiums.

TRAIL REGISTRATION NUMBER

NCT05386901.

Exploring phenotype-based ventilator parameter optimization to mitigate postoperative pulmonary complications: a retrospective observational cohort study

PURPOSE

To identify tidal volume (VT) and positive end-expiratory pressure (PEEP) associated with the lowest incidence and severity of postoperative pulmonary complications (PPCs) for each phenotype based on preoperative characteristics.

METHODS

The subjects of this retrospective observational cohort study were 34,910 adults who underwent surgery, using general anesthesia with mechanical ventilation. Initially, the least absolute shrinkage and selection operator regression was employed to select relevant preoperative characteristics. Then, the classification and regression tree (CART) was built to identify phenotypes. Finally, we computed the area under the receiver operating characteristic curves from logistic regressions to identify VT and PEEP associated with the lowest incidence and severity of PPCs for each phenotype.

RESULTS

CARTs classified seven phenotypes for each outcome. A probability of the development of PPCs ranged from the lowest (3.51%) to the highest (68.57%), whereas the probability of the development of the highest level of PPC severity ranged from 3.3% to 91.0%. Across all phenotypes, the VT and PEEP associated with the most desirable outcomes were within a small range of VT 7-8 ml/kg predicted body weight with PEEP of between 6 and 8 cmH2O.

CONCLUSIONS

The ranges of optimal VT and PEEP were small, regardless of the phenotypes, which had a wide range of risk profiles.

Association between driving pressure-guided ventilation and postoperative pulmonary complications in surgical patients: a meta-analysis with trial sequential analysis

BACKGROUND

Prior studies have reported inconsistent results regarding the association between driving pressure-guided ventilation and postoperative pulmonary complications (PPCs). We aimed to investigate whether driving pressure-guided ventilation is associated with a lower risk of PPCs.

METHODS

We systematically searched electronic databases for RCTs comparing driving pressure-guided ventilation with conventional protective ventilation in adult surgical patients. The primary outcome was a composite of PPCs. Secondary outcomes were pneumonia, atelectasis, and acute respiratory distress syndrome (ARDS). Meta-analysis and subgroup analysis were conducted to calculate risk ratios (RRs) with 95% confidence intervals (CI). Trial sequential analysis (TSA) was used to assess the conclusiveness of evidence.

RESULTS

Thirteen RCTs with 3401 subjects were included. Driving pressure-guided ventilation was associated with a lower risk of PPCs (RR 0.70, 95% CI 0.56-0.87, P=0.001), as indicated by TSA. Subgroup analysis (P for interaction=0.04) found that the association was observed in non-cardiothoracic surgery (nine RCTs, 1038 subjects, RR 0.61, 95% CI 0.48-0.77, P< 0.0001), with TSA suggesting sufficient evidence and conclusive result; however, it did not reach significance in cardiothoracic surgery (four RCTs, 2363 subjects, RR 0.86, 95% CI 0.67-1.10, P=0.23), with TSA indicating insufficient evidence and inconclusive result. Similarly, a lower risk of pneumonia was found in non-cardiothoracic surgery but not in cardiothoracic surgery (P for interaction=0.046). No significant differences were found in atelectasis and ARDS between the two ventilation strategies.

CONCLUSIONS

Driving pressure-guided ventilation was associated with a lower risk of postoperative pulmonary complications in non-cardiothoracic surgery but not in cardiothoracic surgery.

SYSTEMATIC REVIEW PROTOCOL

INPLASY 202410068.

Mechanical power during robotic-assisted laparoscopic prostatectomy: an observational study

BACKGROUND

Robotic-assisted laparoscopic radical prostatectomy (RALP) requires pneumoperitoneum and steep Trendelenburg position. Our aim was to investigate the influence of the combination of pneumoperitoneum and Trendelenburg position on mechanical power and its components during RALP.

METHODS

Sixty-one prospectively enrolled patients scheduled for RALP were studied in supine position before surgery, during pneumoperitoneum and Trendelenburg position and in supine position after surgery at constant ventilatory setting. In a subgroup of 17 patients the response to increasing positive end-expiratory pressure (PEEP) from 5 to 10 cmH2O was studied.

RESULTS

The application of pneumoperitoneum and Trendelenburg position increased the total mechanical power (13.8 [11.6 - 15.5] vs 9.2 [7.5 - 11.7] J/min, p < 0.001) and its elastic and resistive components compared to supine position before surgery. In supine position after surgery the total mechanical power and its elastic component decreased but remained higher compared to supine position before surgery. Increasing PEEP from 5 to 10 cmH2O within each timepoint significantly increased the total mechanical power (supine position before surgery: 9.8 [8.4 - 10.4] vs 12.1 [11.4 - 14.2] J/min, p < 0.001; pneumoperitoneum and Trendelenburg position: 13.8 [12.2 - 14.3] vs 15.5 [15.0 - 16.7] J/min, p < 0.001; supine position after surgery: 10.2 [9.4 - 10.7] vs 12.7 [12.0 - 13.6] J/min, p < 0.001), without affecting respiratory system elastance.

CONCLUSION

Mechanical power in healthy patients undergoing RALP significantly increased both during the pneumoperitoneum and Trendelenburg position and in supine position after surgery. PEEP always increased mechanical power without ameliorating the respiratory system elastance.

Semirecumbent Positioning During Anesthesia Recovery and Postoperative Hypoxemia: A Randomized Clinical Trial

Importance

The efficacy of a semirecumbent position (SRP) in reducing postoperative hypoxemia during anesthesia emergence is unclear despite its widespread use.

Objective

To determine the differences in postoperative hypoxemia between patients in an SRP and a supine position.

Design, Setting, and Participants

This randomized clinical trial was performed at a tertiary hospital in China between March 20, 2021, and May 10, 2022. Patients scheduled to undergo laparoscopic upper abdominal surgery under general anesthesia were enrolled. Study recruitment and follow-up are complete.

Interventions

Patients were randomized to 1 of the following positions at the end of the operation until leaving the postanesthesia care unit: supine (group S), 15° SRP (group F), or 30° SRP (group T).

Main Outcomes and Measures

The primary outcome was the incidence of postoperative hypoxemia in the postanesthesia care unit. Severe hypoxemia was also evaluated.

Results

Out of 700 patients (364 men [52.0%]; mean [SD] age, 47.8 [11.3] years), 233 were randomized to group S (126 men [54.1%]; mean [SD] age, 48.2 [10.9] years), 233 to group F (122 men [52.4%]; mean [SD] age, 48.1 [10.9] years), and 234 to group T (118 women [50.4%]; mean [SD] age, 47.2 [12.1] years). Postoperative hypoxemia differed significantly among the 3 groups (group S, 109 of 233 [46.8%]; group F, 105 of 233 [45.1%]; group T, 76 of 234 [32.5%]; P = .002). This difference was statistically significant for groups T vs S (risk ratio [RR], 0.69 [95% CI, 0.55-0.87]; P = .002) and groups T vs F (RR, 0.72 [95% CI, 0.57-0.91]; P = .007), but not for groups F vs S (RR, 0.96 [95% CI, 0.79-1.17]; P = .78). Severe hypoxemia also differed among the 3 groups (group S, 61 of 233 [26.2%]; group F, 53 of 233 [22.7%]; group T, 36 of 234 [15.4%]; P = .01). This difference was statistically significant for groups T vs S (RR, 0.59 [95% CI, 0.41-0.85]; P = .005).

Conclusions and Relevance

In this randomized clinical trial of SRP during anesthesia recovery in patients undergoing laparoscopic upper abdominal surgery, postoperative hypoxemia was significantly reduced in group T compared with group F or group S.

Trial Registration

Chinese Clinical Trial Registry Identifier: ChiCTR2100045087.

Electrical Impedance Tomography-based Ventilation Patterns in Patients after Major Surgery

Rationale: General anesthesia and mechanical ventilation have negative impacts on the respiratory system, causing heterogeneous distribution of lung aeration, but little is known about the ventilation patterns of postoperative patients and their association with clinical outcomes. Objectives: To clarify the phenotypes of ventilation patterns along a gravitational direction after surgery by using electrical impedance tomography (EIT) and to evaluate their association with postoperative pulmonary complications (PPCs) and other relevant clinical outcomes. Methods: Adult postoperative patients at high risk for PPCs, receiving mechanical ventilation on ICU admission (N = 128), were prospectively enrolled between November 18, 2021 and July 18, 2022. PPCs were prospectively scored until hospital discharge, and their association with phenotypes of ventilation patterns was studied. The secondary outcomes were the times to wean from mechanical ventilation and oxygen use and the length of ICU stay. Measurements and Main Results: Three phenotypes of ventilation patterns were revealed by EIT: phenotype 1 (32% [n = 41], a predominance of ventral ventilation), phenotype 2 (41% [n = 52], homogeneous ventilation), and phenotype 3 (27% [n = 35], a predominance of dorsal ventilation). The median PPC score was higher in phenotype 1 and phenotype 3 than in phenotype 2. The median time to wean from mechanical ventilation was longer in phenotype 1 versus phenotype 2. The median duration of ICU stay was longer in phenotype 1 versus phenotype 2. The median time to wean from oxygen use was longer in phenotype 1 and phenotype 3 than in phenotype 2. Conclusions: Inhomogeneous ventilation patterns revealed by EIT on ICU admission were associated with PPCs, delayed weaning from mechanical ventilation and oxygen use, and a longer ICU stay.

Individualized PEEP guided by EIT in patients undergoing general anesthesia: A systematic review and meta-analysis

BACKGROUND

The determination of optimal positive end-expiratory pressure (PEEP) values in patients undergoing general anesthesia remains controversial. Electrical impedance tomography (EIT) directed individualized PEEP has emerged as a novel approach to PEEP setting and has garnered increasing attention. This meta-analysis aims to systematically assess the effect of EIT-guided PEEP setting compared to traditional fixed PEEP values or other PEEP titration strategies in patients undergoing general anesthesia.

METHODS

A comprehensive search of electronic databases, including PubMed, Web of Science, EMBASE, and the Cochrane Library, was conducted from inception to January 2023, with no language restrictions. The search terms used were "EIT"and "PEEP" with their corresponding free words. Two researchers independently conducted literature screening, data extraction, and quality evaluation. The primary outcomes of interest were oxygenation index (OI), lung compliance, and number of postoperative pulmonary complications (PPCs). The secondary outcomes included mean arterial blood pressure (MAP) and number of vasoactive drug injections. RevMan 5.3 software was used to analyze the data and draw the forest plot, and Stata 14.2 software was used to conduct sensitivity analysis to assess the stability of the results.

RESULTS

5 studies involving 272 participants were included in this meta-analysis. Our findings suggest that EIT-guided individualized PEEP setting is superior to traditional fixed PEEP values and other individualized PEEP titration methods in terms of intraoperative OI(OR = 95.73, 95%CI: (49.10, 142.37); P < 0.0001) and lung compliance(OR = 7.69, 95%CI: (5.55, 9.83); P < 0.00001), without affecting intraoperative hemodynamic parameters such as MAP(OR = 2.07, 95%CI: (-1.00, 5.13); P = 0.19) and the number of intravenous vasoactive drugs(OR = 1.22, 95%CI: (0.68, 2.21); P = 0.51) or increasing the incidence of postoperative PPCs(OR = 0.87, 95%CI: (0.41, 1.82); P = 0.71).

CONCLUSIONS

Our meta-analysis suggests potential benefits of EIT-guided individualized PEEP setting in improving intraoperative oxygenation and lung compliance in patients undergoing general anesthesia. However, further research is needed to establish conclusive evidence, and caution should be exercised in interpreting these findings as the current literature remains inconclusive regarding the impact on intraoperative hemodynamics and postoperative complications.

Use of stepwise lung recruitment maneuver to predict fluid responsiveness under lung protective ventilation in the operating room

Recent research has revealed that hemodynamic changes caused by lung recruitment maneuvers (LRM) with continuous positive airway pressure can be used to identify fluid responders. We investigated the usefulness of stepwise LRM with increasing positive end-expiratory pressure and constant driving pressure for predicting fluid responsiveness in patients under lung protective ventilation (LPV). Forty-one patients under LPV were enrolled when PPV values were in a priori considered gray zone (4% to 17%). The FloTrac-Vigileo device measured stroke volume variation (SVV) and stroke volume (SV), while the patient monitor measured pulse pressure variation (PPV) before and at the end of stepwise LRM and before and 5 min after fluid challenge (6 ml/kg). Fluid responsiveness was defined as a ≥ 15% increase in the SV or SV index. Seventeen were fluid responders. The areas under the curve for the augmented values of PPV and SVV, as well as the decrease in SV by stepwise LRM to identify fluid responders, were 0.76 (95% confidence interval, 0.61-0.88), 0.78 (0.62-0.89), and 0.69 (0.53-0.82), respectively. The optimal cut-offs for the augmented values of PPV and SVV were > 18% and > 13%, respectively. Stepwise LRM -generated augmented PPV and SVV predicted fluid responsiveness under LPV.

Association between mechanical power during one-lung ventilation and pulmonary complications after thoracoscopic lung resection surgery: a prospective observational study

BACKGROUND

The role of mechanical power on pulmonary outcomes after thoracic surgery with one-lung ventilation was unclear. We investigated the association between mechanical power and postoperative pulmonary complications in patients undergoing thoracoscopic lung resection surgery.

METHODS

In this single-center, prospective observational study, 622 patients scheduled for thoracoscopic lung resection surgery were included. Volume control mode with lung protective ventilation strategies were implemented in all participants. The primary endpoint was a composite of postoperative pulmonary complications during hospital stay. Multivariable logistic regression models were used to evaluate the association between mechanical power and outcomes.

RESULTS

The incidence of pulmonary complications after surgery during hospital stay was 24.6% (150 of 609 patients). The multivariable analysis showed that there was no link between mechanical power and postoperative pulmonary complications.

CONCLUSIONS

In patients undergoing thoracoscopic lung resection with standardized lung-protective ventilation, no association was found between mechanical power and postoperative pulmonary complications.

TRIAL REGISTRATION

Trial registration number: ChiCTR2200058528, date of registration: April 10, 2022.

Anesthesia strategies for elderly patients with craniocerebral injury due to foreign-body penetration in the plateau region: a case report

Background

The administration of anesthesia for elderly individuals who are critically ill, suffering from severe craniocerebral injuries, and living in plateau regions presents a rare, intricate, and high-risk challenge. This case study outlines the specific anesthesia management protocols necessary for plateau-dwelling patients with significant craniocerebral damage undergoing prolonged invasive procedures.

Case report

A 76-year-old male patient had a 26-year history of foreign-body penetration of the skull and had experienced local purulent discharge and pain for the previous 20 days. The diagnoses included right hypoplasia, a foreign body in the skull with an infection, hypokalemia, hypoproteinemia, pulmonary fibrous foci, and bilateral pleural effusion. For almost 6 months, the patient suffered from recurring headaches, blurred vision, and sluggish bodily movement. The patient had a poor diet, poor sleep quality, normal urination, and no noticeable weight loss since the onset of the illness. The right anterior ear had a 2 cm skin abscess with yellow pus and a black metal foreign body tip. The left eyelid was red and swollen, and the left conjunctiva was hyperemic; the right eyelid showed no abnormalities, and both pupils were wide and round, with light and adjustment reflexes and no cyanosis on the lips. Skull development was normal. No dry or moist rales were audible in either lung. The heart rhythm was regular, and the heart rate was 50 bpm. Chest CT revealed left lung calcification foci, bilateral pleural effusion, and fiber foci in the lower lobes of both lungs.

Conclusion

Furthermore, the patient in question was of advanced age and had a complex medical history, including prolonged exposure to high altitudes and previous instances of severe craniocerebral trauma, among other uncommon pathophysiological characteristics. In particular, the patient also underwent surgical interventions at both high and low altitudes, adding to the complexity of their case. To ensure patient safety, close multidisciplinary collaboration, the development of a precise surgical plan, and the implementation of a suitable perioperative anesthetic management strategy are imperative.

Dexmedetomidine improves pulmonary outcomes in thoracic surgery under one-lung ventilation: A meta-analysis

INTRODUCTION

Dexmedetomidine improves intrapulmonary shunt in thoracic surgery and minimizes inflammatory response during one-lung ventilation (OLV). However, it is unclear whether such benefits translate into less postoperative pulmonary complications (PPCs). Our objective was to determine the impact of dexmedetomidine on the incidence of PPCs after thoracic surgery.

METHODS

Major databases were used to identify randomized trials that compared dexmedetomidine versus placebo during thoracic surgery in terms of PPCs. Our primary outcome was atelectasis within 7 days after surgery. Other specific PPCs included hypoxemia, pneumonia, and acute respiratory distress syndrome (ARDS). Secondary outcome included intraoperative respiratory mechanics (respiratory compliance [Cdyn]) and postoperative lung function (forced expiratory volume [FEV1]). Random effects models were used to estimate odds ratios (OR).

RESULTS

Twelve randomized trials, including 365 patients in the dexmedetomidine group and 359 in the placebo group, were analyzed in this meta-analysis. Patients in the dexmedetomidine group were less likely to develop postoperative atelectasis (2.3% vs 6.8%, OR 0.42, 95%CI 0.18-0.95, P = 0.04; low certainty) and hypoxemia (3.4% vs 11.7%, OR 0.26, 95%CI 0.10-0.68, P = 0.01; moderate certainty) compared to the placebo group. The incidence of postoperative pneumonia (3.2% vs 5.8%, OR 0.57, 95%CI 0.25-1.26, P = 0.17; moderate certainty) or ARDS (0.9% vs 3.5%, OR 0.39, 95%CI 0.07-2.08, P = 0.27; moderate certainty) was comparable between groups. Both intraoperative Cdyn and postoperative FEV1 were higher among patients that received dexmedetomidine with a mean difference of 4.42 mL/cmH2O (95%CI 3.13-5.72) and 0.27 L (95%CI 0.12-0.41), respectively.

CONCLUSION

Dexmedetomidine administration during thoracic surgery may potentially reduce the risk of postoperative atelectasis and hypoxemia. However, current evidence is insufficient to demonstrate an effect on pneumonia or ARDS.

Restoration of Pulmonary Compliance after Laparoscopic Gynecologic Surgery Using a Recruitment Maneuver

BACKGROUND/OBJECTIVES

This study aimed to investigate the hypothesis that an alveolar recruitment maneuver can restore lung compliance to initial values after laparoscopic gynecological surgery.

METHODS

A total of 31 patients who underwent laparoscopic gynecological surgery were enrolled. Protective mechanical ventilation was applied, and the radial artery was catheterized in all patients. An alveolar recruitment maneuver (incremental and decremental positive end-expiratory pressure) was applied ten minutes after the release of pneumoperitoneum. The respiratory mechanics and blood gas results were recorded at eight different time points: after induction of anesthesia (T1), in the lithotomy position (T2), in the Trendelenburg position (T3), 10 and 90 min after insufflation of carbon dioxide (T4 and T5), in the supine position (T6), after desufflation (T7), and 10 min after an alveolar recruitment maneuver at the end of surgery (T8).

RESULTS

Pneumoperitoneum and the Trendelenburg position caused a decline of 15 units in compliance (T7 vs. T1; p < 0.05) compared to baseline. After the alveolar recruitment maneuver, compliance increased by 17.5% compared with the mean value of compliance at time T1 (T8 vs. T1; p < 0.05). The recruitment maneuver had favorable results in patients with low initial compliance (41.5 mL/cmH2O, IQR: 9.75 mL/cmH2O), high Body Mass Index 30.32 kg/m2 (IQR: 1.05 kg/m2), and high initial plateau airway pressure (16.5 cmH2O, IQR: 0.75 cmH2O).

CONCLUSIONS

Lung compliance does not return to initial values after performing laparoscopic gynecological procedures. However, after the release of pneumoperitoneum, an alveolar recruitment maneuver is beneficial as it improves compliance and gas exchange.

The Effect of Recruitment Maneuver on Static Lung Compliance in Patients Undergoing General Anesthesia for Laparoscopic Cholecystectomy: A Single-Centre Prospective Clinical Intervention Study

Background and Objectives: The aim of this study was to examine whether the use of an alveolar recruitment maneuver (RM) leads to a significant increase in static lung compliance (Cstat) and an improvement in gas exchange in patients undergoing laparoscopic cholecystectomy. Material and Methods: A clinical prospective intervention study was conducted. Patients were divided into two groups according to their body mass index (BMI): normal-weight (group I) and pre-obese and obese grade I (group II). Lung mechanics were monitored (Cstat, dynamic compliance-Cdin, peak pressure-Ppeak, plateau pressure-Pplat, driving pressure-DP) alongside gas exchange, and hemodynamic changes (heart rate-HR, mean arterial pressure-MAP) at six time points: T1 (induction of anesthesia), T2 (formation of pneumoperitoneum), T3 (RM with a PEEP of 5 cm H2O), T4 (RM with a PEEP of 7 cm H2O), T5 (desufflation), and T6 (RM at the end). The RM was performed by increasing the peak pressure by +5 cm of H2O at an equal inspiration-to-expiration ratio (I/E = 1:1) and applying a PEEP of 5 and 7 cm of H2O. Results: Out of 96 patients, 33 belonged to group I and 63 to group II. An increase in Cstat values occurred after all three RMs. At each time point, the Cstat value was measured higher in group I than in group II. A higher increase in Cstat was observed in group II after the second and third RM. Cstat values were higher at the end of the surgical procedure compared to values after the induction of anesthesia. The RM led to a significant increase in PaO2 in both groups without changes in HR or MAP. Conclusions: During laparoscopic cholecystectomy, the application of RM leads to a significant increase in Cstat and an improvement in gas exchange. The prevention of atelectasis during anesthesia should be initiated immediately after the induction of anesthesia, using protective mechanical ventilation and RM.

Apnea during moderate to deep sedation using continuous infusion of remimazolam compared to propofol and dexmedetomidine: A retrospective observational study

Remimazolam's rapid onset and offset make it an innovative sedative for use during regional anesthesia. However, its respiratory safety profile is not well understood. We compared the continuous infusion of remimazolam with commonly used sedatives, propofol and dexmedetomidine, after regional anesthesia. In this retrospective study, the incidence of apnea (>10 seconds) was assessed in patients who underwent orthopedic surgery under regional anesthesia and received moderate to deep sedation using continuous infusion of remimazolam (group R: 0.1 mg/kg in 2 minutes followed by 0.5 mg/kg/hr). The incidence was compared with that of propofol (group P: 2-3 μg/mL target-controlled infusion) and dexmedetomidine (group D: 1 μg/kg in 10 minutes followed by 0.4-1 μg/kg/hr). Propensity score weighted multivariable logistic regression model was utilized to determine the effects of the sedative agents on the incidence of apnea. A total of 634 (191, 278, and 165 in group R, P, and D) cases were included in the final analysis. The incidence of apnea was 63.9%, 67.3%, and 48.5% in group R, P, and D, respectively. The adjusted odds ratios for apnea were 2.33 (95% CI, 1.50 to 3.61) and 2.50 (95% CI, 1.63 to 3.85) in group R and P, compared to group D. The incidence of apnea in patients receiving moderate to deep sedation using continuous infusion of remimazolam with dosage suggested in the current study was over 60%. Therefore, careful titration and respiratory monitoring is warranted.

Noninvasive respiratory support in the perioperative setting: a narrative review

The application of preoperative noninvasive respiratory support (NRS) has been expanding with increasing recognition of its potential role in this setting as a physiological optimization for patients with a high risk of developing atelectasis and postoperative pulmonary complications (PPC). The increased availability of high-performance anesthesia ventilator machines providing an easy way for NRS support in patients with reduced lung function should not be under-evaluated. This support can reduce hypoxia, restore lung volumes and theoretically reduce atelectasis formation after general anesthesia. Therapeutic purposes should also be considered in the perioperative setting, such as preoperative NRS to optimize treatment of patients' pre-existing diseases, e.g., sleep-disordered breathing. Finally, the recent guidelines for airway management suggest preoperative NRS application before anesthesia induction in difficult airway management to prolong the time needed to secure the airway with an orotracheal tube. This narrative review aims to revise all these aspects and to provide some practical notes to maximize the efficacy of perioperative noninvasive respiratory support.

Intraoperative lung protection: strategies and their impact on outcomes

PURPOSE OF REVIEW

The present review summarizes the current knowledge and the barriers encountered when implementing tailoring lung-protective ventilation strategies to individual patients based on advanced monitoring systems.

RECENT FINDINGS

Lung-protective ventilation has become a pivotal component of perioperative care, aiming to enhance patient outcomes and reduce the incidence of postoperative pulmonary complications (PPCs). High-quality research has established the benefits of strategies such as low tidal volume ventilation and low driving pressures. Debate is still ongoing on the most suitable levels of positive end-expiratory pressure (PEEP) and the role of recruitment maneuvers. Adapting PEEP according to patient-specific factors offers potential benefits in maintaining ventilation distribution uniformity, especially in challenging scenarios like pneumoperitoneum and steep Trendelenburg positions. Advanced monitoring systems, which continuously assess patient responses and enable the fine-tuning of ventilation parameters, offer real-time data analytics to predict and prevent impending lung complications. However, their impact on postoperative outcomes, particularly PPCs, is an ongoing area of research.

SUMMARY

Refining protective lung ventilation is crucial to provide patients with the best possible care during surgery, reduce the incidence of PPCs, and improve their overall surgical journey.

Continuous positive airway pressure combined with small-tidal-volume ventilation on arterial oxygenation and pulmonary shunt during one-lung ventilation in patients undergoing video-assisted thoracoscopic lobectomy: A randomized, controlled study

BACKGROUND

One-lung ventilation (OLV) is frequently applied during video-assisted thoracoscopic surgery (VATS) airway management to collapse and isolate the nondependent lung (NL). OLV can give rise to hypoxemia as a result of the pulmonary shunting produced. Our study aimed to assess the influence of continuous positive airway pressure (CPAP) combined with small-tidal-volume ventilation on improving arterial oxygenation and decreasing pulmonary shunt rate (QS/QT) without compromising surgical field exposure during OLV.

METHODS

Forty-eight patients undergoing scheduled VATS lobectomy were enrolled in this research and allocated into three groups at random: C group (conventional ventilation, no NL ventilation intervention was performed), LP group (NL was ventilated with lower CPAP [2 cmH2O] and a 40-60 mL tidal volume [TV]), and HP group (NL was ventilated with higher CPAP [5 cmH2O] and a 60-80 mL TV). Record the blood gas analysis data and calculate the QS/QT at the following time: at the beginning of the OLV (T0), 30 min after OLV (T1), and 60 min after OLV (T2). Surgeons blinded to ventilation techniques were invited to evaluate the surgical fields.

RESULTS

The demography data of the three groups were consistent with the surgical data. At T1, PaO2 in the HP group was substantially higher compared to the C group (P < 0.05), while there was no significant difference in the LP group (P > 0.05). At T1-T2, PaCO2 in the LP and HP groups was significantly less than that in the C group (P < 0.05). At T1, the QS/QT values of groups C, LP, and HP were 29.54 ± 6.89%, 22.66 ± 2.08%, and 19.64 ± 5.76%, respectively, and the QS/QT values in the LP and HP groups markedly reduced (P < 0.01). The surgical field's evaluation by the surgeon among the three groups was not notable (P > 0.05).

CONCLUSION

CPAP combined with small-tidal-volume ventilation effectively improved arterial oxygenation and reduced QS/QT and PaCO2 without compromising surgical field exposure during OLV. Among them, 5 cmH2O CPAP + 60-80 ml TV ventilation had a better effect on improving oxygenation.

Linking preoperative and early intensive care unit data for prolonged intubation prediction

Objectives

Prolonged intubation (PI) is a frequently encountered severe complication among patients following cardiac surgery (CS). Solely concentrating on preoperative data, devoid of sufficient consideration for the ongoing impact of surgical, anesthetic, and cardiopulmonary bypass procedures on subsequent respiratory system function, could potentially compromise the predictive accuracy of disease prognosis. In response to this challenge, we formulated and externally validated an intelligible prediction model tailored for CS patients, leveraging both preoperative information and early intensive care unit (ICU) data to facilitate early prophylaxis for PI.

Methods

We conducted a retrospective cohort study, analyzing adult patients who underwent CS and utilizing data from two publicly available ICU databases, namely, the Medical Information Mart for Intensive Care and the eICU Collaborative Research Database. PI was defined as necessitating intubation for over 24 h. The predictive model was constructed using multivariable logistic regression. External validation of the model's predictive performance was conducted, and the findings were elucidated through visualization techniques.

Results

The incidence rates of PI in the training, testing, and external validation cohorts were 11.8%, 12.1%, and 17.5%, respectively. We identified 11 predictive factors associated with PI following CS: plateau pressure [odds ratio (OR), 1.133; 95% confidence interval (CI), 1.111-1.157], lactate level (OR, 1.131; 95% CI, 1.067-1.2), Charlson Comorbidity Index (OR, 1.166; 95% CI, 1.115-1.219), Sequential Organ Failure Assessment score (OR, 1.096; 95% CI, 1.061-1.132), central venous pressure (OR, 1.052; 95% CI, 1.033-1.073), anion gap (OR, 1.075; 95% CI, 1.043-1.107), positive end-expiratory pressure (OR, 1.087; 95% CI, 1.047-1.129), vasopressor usage (OR, 1.521; 95% CI, 1.23-1.879), Visual Analog Scale score (OR, 0.928; 95% CI, 0.893-0.964), pH value (OR, 0.757; 95% CI, 0.629-0.913), and blood urea nitrogen level (OR, 1.011; 95% CI, 1.003-1.02). The model exhibited an area under the receiver operating characteristic curve (AUROC) of 0.853 (95% CI, 0.840-0.865) in the training cohort, 0.867 (95% CI, 0.853-0.882) in the testing cohort, and 0.704 (95% CI, 0.679-0.727) in the external validation cohort.

Conclusions

Through multicenter internal and external validation, our model, which integrates early ICU data and preoperative information, exhibited outstanding discriminative capability. This integration allows for the accurate assessment of PI risk in the initial phases following CS, facilitating timely interventions to mitigate adverse outcomes.

Effects of positive end-expiratory pressure on regional cerebral oxygen saturation in elderly patients undergoing thoracic surgery during one-lung ventilation: a randomized crossover-controlled trial

BACKGROUND

A significant reduction in regional cerebral oxygen saturation (rSO2) is commonly observed during one-lung ventilation (OLV), while positive end-expiratory pressure (PEEP) can improve oxygenation. We compared the effects of three different PEEP levels on rSO2, pulmonary oxygenation, and hemodynamics during OLV.

METHODS

Forty-three elderly patients who underwent thoracoscopic lobectomy were randomly assigned to one of six PEEP combinations which used a crossover design of 3 levels of PEEP-0 cmH2O, 5 cmH2O, and 10 cmH2O. The primary endpoint was rSO2 in patients receiving OLV 20 min after adjusting the PEEP. The secondary outcomes included hemodynamic and respiratory variables.

RESULTS

After exclusion, thirty-six patients (36.11% female; age range: 60-76 year) were assigned to six groups (n = 6 in each group). The rSO2 was highest at OLV(0) than at OLV(10) (difference, 2.889%; [95% CI, 0.573 to 5.204%]; p = 0.008). Arterial oxygen partial pressure (PaO2) was lowest at OLV(0) compared with OLV(5) (difference, -62.639 mmHg; [95% CI, -106.170 to -19.108 mmHg]; p = 0.005) or OLV(10) (difference, -73.389 mmHg; [95% CI, -117.852 to -28.925 mmHg]; p = 0.001), while peak airway pressure (Ppeak) was lower at OLV(0) (difference, -4.222 mmHg; [95% CI, -5.140 to -3.304 mmHg]; p < 0.001) and OLV(5) (difference, -3.139 mmHg; [95% CI, -4.110 to -2.167 mmHg]; p < 0.001) than at OLV(10).

CONCLUSIONS

PEEP with 10 cmH2O makes rSO2 decrease compared with 0 cmH2O. Applying PEEP with 5 cmH2O during OLV in elderly patients can improve oxygenation and maintain high rSO2 levels, without significantly increasing peak airway pressure compared to not using PEEP.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2200060112 on 19 May 2022.

Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV): a multicentre, randomised, controlled clinical trial

BACKGROUND

It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation.

METHODS

This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age ≥18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lung-protective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete.

FINDINGS

Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0·39 [95% CI 0·28 to 0·56]), with an absolute risk difference of -9·23 (95% CI -12·55 to -5·92). Recruitment manoeuvre-related adverse events were reported in five patients.

INTERPRETATION

Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation.

FUNDING

Instituto de Salud Carlos III and the European Regional Development Funds.

Intraoperative Mechanical Power and Postoperative Pulmonary Complications in Noncardiothoracic Elective Surgery Patients: A 10-Year Retrospective Cohort Study

BACKGROUND

Postoperative pulmonary complications is a major issue that affects outcomes of surgical patients. The hypothesis was that the intraoperative ventilation parameters are associated with occurrence of postoperative pulmonary complications.

METHODS

A single-center retrospective cohort study was conducted at the Lille University Hospital, France. The study included 33,701 adults undergoing noncardiac, nonthoracic elective surgery requiring general anesthesia with tracheal intubation between January 2010 and December 2019. Intraoperative ventilation parameters were compared between patients with and without one or more postoperative pulmonary complications (respiratory infection, respiratory failure, pleural effusion, atelectasis, pneumothorax, bronchospasm, and aspiration pneumonitis) within 7 days of surgery.

RESULTS

Among 33,701 patients, 2,033 (6.0%) had one or more postoperative pulmonary complications. The lower tidal volume to predicted body weight ratio (odds ratio per -1 ml·kgPBW-1, 1.08; 95% CI, 1.02 to 1.14; P < 0.001), higher mechanical power (odds ratio per 4 J·min-1, 1.37; 95% CI, 1.26 to 1.49; P < 0.001), dynamic respiratory system compliance less than 30 ml·cm H2O (1.30; 95% CI, 1.15 to 1.46; P < 0.001), oxygen saturation measured by pulse oximetry less than 96% (odds ratio, 2.42; 95% CI, 1.97 to 2.96; P < 0.001), and lower end-tidal carbon dioxide (odds ratio per -3 mmHg, 1.06; 95% CI, 1.00 to 1.13; P = 0.023) were independently associated with postoperative pulmonary complications. Patients with postoperative pulmonary complications were more likely to be admitted to the intensive care unit (odds ratio, 12.5; 95% CI, 6.6 to 10.1; P < 0.001), had longer hospital length of stay (subhazard ratio, 0.43; 95% CI, 0.40 to 0.45), and higher in-hospital (subhazard ratio, 6.0; 95% CI, 4.1 to 9.0; P < 0.001) and 1-yr mortality (subhazard ratio, 2.65; 95% CI, 2.33 to 3.02; P < 0.001).

CONCLUSIONS

In the study's population, decreased rather than increased tidal volume, decreased compliance, increased mechanical power, and decreased end-tidal carbon dioxide were independently associated with postoperative pulmonary complications.

EDITOR’S PERSPECTIVE

Mechanical Ventilation, Past, Present, and Future

Mechanical ventilation (MV) has played a crucial role in the medical field, particularly in anesthesia and in critical care medicine (CCM) settings. MV has evolved significantly since its inception over 70 years ago and the future promises even more advanced technology. In the past, ventilation was provided manually, intermittently, and it was primarily used for resuscitation or as a last resort for patients with severe respiratory or cardiovascular failure. The earliest MV machines for prolonged ventilatory support and oxygenation were large and cumbersome. They required a significant amount of skills and expertise to operate. These early devices had limited capabilities, battery, power, safety features, alarms, and therefore these often caused harm to patients. Moreover, the physiology of MV was modified when mechanical ventilators moved from negative pressure to positive pressure mechanisms. Monitoring systems were also very limited and therefore the risks related to MV support were difficult to quantify, predict and timely detect for individual patients who were necessarily young with few comorbidities. Technology and devices designed to use tracheostomies versus endotracheal intubation evolved in the last century too and these are currently much more reliable. In the present, positive pressure MV is more sophisticated and widely used for extensive period of time. Modern ventilators use mostly positive pressure systems and are much smaller, more portable than their predecessors, and they are much easier to operate. They can also be programmed to provide different levels of support based on evolving physiological concepts allowing lung-protective ventilation. Monitoring systems are more sophisticated and knowledge related to the physiology of MV is improved. Patients are also more complex and elderly compared to the past. MV experts are informed about risks related to prolonged or aggressive ventilation modalities and settings. One of the most significant advances in MV has been protective lung ventilation, diaphragm protective ventilation including noninvasive ventilation (NIV). Health care professionals are familiar with the use of MV and in many countries, respiratory therapists have been trained for the exclusive purpose of providing safe and professional respiratory support to critically ill patients. Analgo-sedation drugs and techniques are improved, and more sedative drugs are available and this has an impact on recovery, weaning, and overall patients' outcome. Looking toward the future, MV is likely to continue to evolve and improve alongside monitoring techniques and sedatives. There is increasing precision in monitoring global "patient-ventilator" interactions: structure and analysis (asynchrony, desynchrony, etc). One area of development is the use of artificial intelligence (AI) in ventilator technology. AI can be used to monitor patients in real-time, and it can predict when a patient is likely to experience respiratory distress. This allows medical professionals to intervene before a crisis occurs, improving patient outcomes and reducing the need for emergency intervention. This specific area of development is intended as "personalized ventilation." It involves tailoring the ventilator settings to the individual patient, based on their physiology and the specific condition they are being treated for. This approach has the potential to improve patient outcomes by optimizing ventilation and reducing the risk of harm. In conclusion, MV has come a long way since its inception, and it continues to play a critical role in anesthesia and in CCM settings. Advances in technology have made MV safer, more effective, affordable, and more widely available. As technology continues to improve, more advanced and personalized MV will become available, leading to better patients' outcomes and quality of life for those in need.

Effect of Mechanical Ventilation Mode Type on Postoperative Pulmonary Complications After Cardiac Surgery: A Randomized Controlled Trial

OBJECTIVES

It is unknown whether there is a difference in pulmonary outcome in different intraoperative ventilation modes for cardiac surgery with cardiopulmonary bypass (CPB). The aim of this trial was to determine whether patients undergoing cardiac surgery with CPB could benefit from intraoperative optimal ventilation mode.

DESIGN

This was a single-center, prospective, randomized controlled trial.

SETTING

The study was conducted at a single-center tertiary-care hospital.

PARTICIPANTS

A total of 1,364 adults undergoing cardiac surgery with CPB participated in this trial.

INTERVENTIONS

Patients were assigned randomly (1:1:1) to receive 1 of 3 ventilation modes: volume-controlled ventilation (VCV), pressure-controlled ventilation (PCV), and pressure-controlled ventilation-volume guaranteed (PCV-VG). All arms of the study received the lung-protective ventilation strategy.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was a composite of postoperative pulmonary complications (PPCs) within the first 7 postoperative days. Pulmonary complications occurred in 168 of 455 patients (36.9%) in the PCV-VG group, 171 (37.6%) in the PCV group, and 182 (40.1%) in the VCV group, respectively. There was no statistical difference in the risk of overall pulmonary complications among groups (p = 0.585). There were no significant differences in the severity grade of PPCs within 7 days, postoperative ventilation duration, intensive care unit stay, postoperative hospital stay, or 30-day postoperative mortality.

CONCLUSIONS

Among patients scheduled for cardiac surgery with CPB, intraoperative ventilation mode type did not affect the risk of postoperative pulmonary complications.

Postoperative pulmonary complications with high versus standard FiO2 in adult patients undergoing major abdominal surgery: A noninferiority trial

BACKGROUND

Despite the possible clinical benefit of high intraoperative oxygen therapy on surgical site infection, the effect on postoperative respiratory function is debatable. However, it remains yet to be elucidated whether hyperoxia due to a high fraction of inspired oxygen used in conjunction with lung protective ventilation can lead to increased incidence of postoperative pulmonary complications.

METHODS

In this noninferiority randomized trial, an intraoperative high fraction of inspired oxygen of 0.8 (group H) was compared to a standard fraction of inspired oxygen of 0.3 to 0.4 (group S) in adult patients undergoing major elective or emergency surgery. A lung protective ventilation strategy was employed in all patients, including volume control ventilation with a tidal volume of 6 to 8 mL/kg of predicted body weight, respiratory rate of 12 beats per minute, and positive end-expiratory pressure of 5 to 8 cm H2O. Postoperative pulmonary complications were assessed on postoperative days 3 and 5 by the Melbourne group scale.

RESULTS

In this trial, n = 226 patients were randomized; among them, 130 patients underwent routine surgery, and 96 patients underwent emergency surgery. The median (interquartile range) of the patients was 48 (35-58) years, and 47.3% were female. Melbourne group scale scores at postoperative day 3 (median [interquartile range] 2 [1-4] in group S vs 2 [1-3] in group H; the difference in median [95% confidence interval] 0 [0, -1]; P = .13) and day 5 (median [interquartile range] 1 (0-3) in group S vs 1 [0-3] in group H; the difference in median [95% confidence interval] 0 [0, 0.5]; P = .34) were statistically similar in both the groups and the upper margin was within the predefined margin of 1. Incidence of surgical site infection (P = .46), postoperative hospital stay (P = .29), and days alive without antibiotic therapy at postoperative day 28 (P = .95) were similar in both groups.

CONCLUSION

High intraoperative fiO2 was noninferior to standard fiO2 in postoperative pulmonary complications in adult patients undergoing major surgery.

Effects of individualized positive end-expiratory pressure on intraoperative oxygenation in thoracic surgical patients: study protocol for a prospective randomized controlled trial

BACKGROUND

Intraoperative hypoxemia and postoperative pulmonary complications (PPCs) often occur in patients with one-lung ventilation (OLV), due to both pulmonary shunt and atelectasis. It has been demonstrated that individualized positive end-expiratory pressure (iPEEP) can effectively improve intraoperative oxygenation, increase lung compliance, and reduce driving pressure, thereby decreasing the risk of developing PPCs. However, its effect during OLV is still unknown. Therefore, we aim to investigate whether iPEEP ventilation during OLV is superior to 5 cmH2O PEEP in terms of intraoperative oxygenation and the occurrence of PPCs.

METHODS

This study is a prospective, randomized controlled, single-blind, single-center trial. A total of 112 patients undergoing thoracoscopic pneumonectomy surgery and OLV will be enrolled in the study. They will be randomized into two groups: the static lung compliance guided iPEEP titration group (Cst-iPEEP Group) and the constant 5 cmH2O PEEP group (PEEP 5 Group). The primary outcome will be the oxygenation index at 30 min after OLV and titration. Secondary outcomes are oxygenation index at other operative time points, PPCs, postoperative adverse events, ventilator parameters, vital signs, pH value, inflammatory factors, and economic indicators.

DISCUSSION

This trial explores the effect of iPEEP on intraoperative oxygenation during OLV and PPCs. It provides some clinical references for optimizing the lung protective ventilation strategy of OLV, improving patient prognosis, and accelerating postoperative rehabilitation.

TRIAL REGISTRATION

www.Chictr.org.cn ChiCTR2300073411 . Registered on 10 July 2023.

Positive end-expiratory pressure during one-lung ventilation for preventing atelectasis after video-assisted thoracoscopic surgery: a triple-arm, randomized controlled trial

BACKGROUND

There is little evidence regarding the benefits of lung-protective ventilation in patients undergoing one-lung ventilation for thoracic surgery. This study aimed to determine the optimal level of positive end-expiratory pressure (PEEP) during one-lung ventilation for minimizing postoperative atelectasis through lung ultrasonography.

METHODS

A total of 142 adult patients scheduled for video-assisted thoracoscopic surgery at Seoul National University Hospital between May 2019 and February 2020 were enrolled in this study. Patients were randomly assigned to different groups: 1) PEEP 3 cmH2O group; 2) PEEP 6 cmH2O group; and 3) PEEP 9 cmH2O group during one-lung ventilation. The lung ultrasound score was used to evaluate lung aeration using ultrasonography 1 hour after surgery.

RESULTS

The 1-hour post-surgery lung ultrasound scores were 8.1±2.5, 6.8±2.6, and 5.9±2.6 in the PEEP 3, 6, and 9 cmH2O groups, respectively (P<0.001). The PEEP 3 cmH2O group showed significantly higher lung ultrasound scores than the PEEP 6 (adjusted P=0.034) and 9 cmH2O groups (adjusted P<0.001). The PaO2/FiO2 ratio measured at 10 minutes after the end of one-lung ventilation was significantly lower in the PEEP 3 cmH2O group (392 [331 to 469]) than the PEEP 6 cmH2O (458 [384 to 530], adjusted P=0.018) or PEEP 9 cmH2O groups (454 [374 to 522], adjusted P=0.016).

CONCLUSIONS

Although the optimal level of PEEP during one-lung ventilation was not determined, the application of higher PEEP can prevent aeration loss in the ventilated lung after video-assisted thoracoscopic surgery under one-lung ventilation.

The Impact of Postoperative Pulmonary Complications on Perioperative Outcomes in Patients Undergoing Pneumonectomy: A Multicenter Retrospective Cohort Study of the German Thorax Registry

Postoperative pulmonary complications have a deleterious impact in regards to thoracic surgery. Pneumonectomy is associated with the highest perioperative risk in elective thoracic surgery. The data from 152 patients undergoing pneumonectomy in this multicenter retrospective study were extracted from the German Thorax Registry database and presented after univariate and multivariate statistical processing. This retrospective study investigated the incidence of postoperative pulmonary complications (PPCs) and their impact on perioperative morbidity and mortality. Patient-specific, preoperative, procedural, and postoperative risk factors for PPCs and in-hospital mortality were analyzed. A total of 32 (21%) patients exhibited one or more PPCs, and 11 (7%) died during the hospital stay. Multivariate stepwise logistic regression identified a preoperative FEV1 < 50% (OR 9.1, 95% CI 1.9-67), the presence of medical complications (OR 7.4, 95% CI 2.7-16.2), and an ICU stay of more than 2 days (OR 14, 95% CI 3.9-59) as independent factors associated with PPCs. PPCs (OR 13, 95% CI 3.2-52), a preoperative FEV1 < 60% in patients with previous pulmonary infection (OR 21, 95% CI 3.2-52), and continued postoperative mechanical ventilation (OR 8.4, 95% CI 2-34) were independent factors for in-hospital mortality. Our data emphasizes that PPCs are a significant risk factor for morbidity and mortality after pneumonectomy. Intensified perioperative care targeting the underlying risk factors and effects of PPCs, postoperative ventilation, and preoperative respiratory infections, especially in patients with reduced pulmonary reserve, could improve patient outcomes.

Flow-controlled versus pressure-controlled ventilation in cardiac surgery with cardiopulmonary bypass - A single-center, prospective, randomized, controlled trial

STUDY OBJECTIVE

Multifactorial comparison of flow-controlled ventilation (FCV) to standard of pressure-controlled ventilation (PCV) in terms of oxygenation in cardiac surgery patients after chest closure.

DESIGN

Prospective, non-blinded, randomized, controlled trial.

SETTING

Operating theatre at an university hospital, Austria.

PATIENTS

Patients scheduled for elective, open, on-pump, cardiac surgery.

INTERVENTIONS

Participants were randomized to either individualized FCV (compliance guided end-expiratory and peak pressure setting) or control of PCV (compliance guided end-expiratory pressure setting and tidal volume of 6-8 ml/kg) for the duration of surgery.

MEASUREMENTS

The primary outcome measure was oxygenation (PaO2/FiO2) 15 min after intraoperative chest closure. Secondary endpoints included CO2-removal assessed as required minute volume to achieve normocapnia and lung tissue aeration assessed by Hounsfield unit distribution in postoperative computed tomography scans.

MAIN RESULTS

Between April 2020 and April 2021 56 patients were enrolled and 50 included in the primary analysis (mean age 70 years, 38 (76%) men). Oxygenation, assessed by PaO2/FiO2, was significantly higher in the FCV group (n = 24) compared to the control group (PCV, n = 26) (356 vs. 309, median difference (MD) 46 (95% CI 3 to 90) mmHg; p = 0.038). Additionally, the minute volume required to obtain normocapnia was significantly lower in the FCV group (4.0 vs. 6.1, MD -2.0 (95% CI -2.5 to -1.5) l/min; p < 0.001) and correlated with a significantly lower exposure to mechanical power (5.1 vs. 9.8, MD -5.1 (95% CI -6.2 to -4.0) J/min; p < 0.001). Evaluation of lung tissue aeration revealed a significantly reduced amount of non-aerated lung tissue in FCV compared to PCV (5 vs. 7, MD -3 (95% CI -4 to -1) %; p < 0.001).

CONCLUSIONS

In patients undergoing on-pump, cardiac surgery individualized FCV significantly improved oxygenation and lung tissue aeration compared to PCV. In addition, carbon dioxide removal was accomplished at a lower minute volume leading to reduced applied mechanical power.

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.

Improving Certified Registered Nurse Anesthetists' Adherence to a Standardized Intraoperative Lung Protective Ventilation Protocol

PURPOSE

The use of lung protective ventilation (LPV) during general anesthesia is an effective strategy among certified registered nurse anesthetists (CRNAs) to reduce and prevent the incidence of postoperative pulmonary complications. The purpose of this project was to implement a LPV protocol, assess CRNA provider adherence, and investigate differences in ventilation parameters and postoperative oxygen requirements.

DESIGN

This quality improvement project was conducted using a pre- and postimplementation design.

METHODS

Sixty patients undergoing robotic laparoscopic abdominal surgery and 35 CRNAs at a community hospital participated. An evidence-based intraoperative LPV protocol was developed, CRNA education was provided, and the protocol was implemented. Pre- and postimplementation, CRNA knowledge, and confidence were assessed. Ventilation data were collected at 1-minute intervals intraoperatively and oxygen requirements were recorded in the postanesthesia care unit (PACU).

FINDINGS

Use of intraoperative LPV strategies increased 2.4%. Overall CRNA knowledge (P = .588), confidence (P = .031), and practice (P < .001) improved from pre- to postimplementation. Driving pressures decreased from pre- to postimplementation (P < .001). Supplemental oxygen use on admission to the PACU decreased from 93.3% to 70.0%.

CONCLUSIONS

Educational interventions and implementation of a standardized protocol can improve the use of intraoperative LPV strategies and patient outcomes.

The intraoperative management of robotic-assisted laparoscopic prostatectomy

PURPOSE OF REVIEW

Robotic-assisted laparoscopic radical prostatectomy has become the second most commonly performed robotic surgical procedure worldwide, therefore, anesthesiologists should be aware of the intraoperative pathophysiological consequences. The aim of this narrative review is to report the most recent updates regarding the intraoperative management of anesthesia, ventilation, hemodynamics and central nervous system, during robotic-assisted laparoscopic radical prostatectomy.

RECENT FINDINGS

Surgical innovations and the advent of new technologies make it imperative to optimize the anesthesia management to provide the most holistic approach possible. In addition, an ageing population with an increasing burden of comorbidities requires multifocal attention to reduce the surgical stress.

SUMMARY

Total intravenous anesthesia (TIVA) and balanced general anesthesia are similar in terms of postoperative complications and hospital stay. Reversal of rocuronium is associated with shorter hospital stay and postanesthesia recovery time. Adequate PEEP levels improve oxygenation and driving pressure, and the use of a single recruitment maneuver after the intubation reduces postoperative pulmonary complications. Restrictive intravenous fluid administration minimizes bladder-urethra anastomosis complications and facial edema. TIVA maintains a better autoregulation compared with balanced general anesthesia. Anesthesiologists should be able to optimize the intraoperative management to improve outcomes.

Pressure-controlled versus manual facemask ventilation for anaesthetic induction in adults: A randomised controlled non-inferiority trial

BACKGROUND

Pressure-controlled face mask ventilation (PC-FMV) with positive end-expiratory pressure (PEEP) after apnoea following induction of general anaesthesia prolongs safe apnoea time and reduces atelectasis formation. However, depending on the set inspiratory pressure, a delayed confirmation of a patent airway might occur. We hypothesised that by lowering the peak inspiratory pressure (PIP) when using PC-FMV with PEEP, confirmation of a patent airway would not be delayed as studied by the first return of CO2 , compared with manual face mask ventilation (Manual FMV).

METHODS

This was a single-centre, randomised controlled non-inferiority trial. Seventy adult patients scheduled for elective day-case surgery under general anaesthesia with body mass index between 18.5 and 29.9 kg m-2 , American Society of Anesthesiologists (ASA) classes I-III, and without anticipated difficult FMV, were included. Before the start of pre-oxygenation and induction of general anaesthesia, participants were randomly allocated to receive ventilation with either PC-FMV with PEEP, at a PIP of 11 and a PEEP of 6 cmH2 O or Manual FMV, with the adjustable pressure-limiting valve set at 11 cmH2 O. The primary outcome variable was the number of ventilatory attempts needed until confirmation of a patent airway, defined as the return of at least 1.3 kPa CO2 .

RESULTS

The return of ≥1.3 kPa CO2 on the capnography curve was observed after mean ± SD, 3.6 ± 4.2 and 2.5 ± 1.9 ventilatory attempts/breaths with PC-FMV with PEEP and Manual FMV, respectively. The difference in means (1.1 ventilatory attempts/breaths) had a 99% CI of -1.0 to 3.1, within the accepted upper margin of four breaths for non-inferiority.

CONCLUSION

Following induction of general anaesthesia, PC-FMV with PEEP was used without delaying a patent airway as confirmed with capnography, if moderate pressures were used.

Development of an automated, general-purpose prediction tool for postoperative respiratory failure using machine learning: A retrospective cohort study

STUDY OBJECTIVE

Postoperative respiratory failure is a major surgical complication and key quality metric. Existing prediction tools underperform, are limited to specific populations, and necessitate manual calculation. This limits their implementation. We aimed to create an improved, machine learning powered prediction tool with ideal characteristics for automated calculation.

DESIGN, SETTING, AND PATIENTS

We retrospectively reviewed 101,455 anesthetic procedures from 1/2018 to 6/2021. The primary outcome was the Standardized Endpoints in Perioperative Medicine consensus definition for postoperative respiratory failure. Secondary outcomes were respiratory quality metrics from the National Surgery Quality Improvement Sample, Society of Thoracic Surgeons, and CMS. We abstracted from the electronic health record 26 procedural and physiologic variables previously identified as respiratory failure risk factors. We randomly split the cohort and used the Random Forest method to predict the composite outcome in the training cohort. We coined this the RESPIRE model and measured its accuracy in the validation cohort using area under the receiver operating curve (AUROC) analysis, among other measures, and compared this with ARISCAT and SPORC-1, two leading prediction tools. We compared performance in a validation cohort using score cut-offs determined in a separate test cohort.

MAIN RESULTS

The RESPIRE model exhibited superior accuracy with an AUROC of 0.93 (95% CI, 0.92-0.95) compared to 0.82 for both ARISCAT and SPORC-1 (P-for-difference < 0.0001 for both). At comparable 80-90% sensitivities, RESPIRE had higher positive predictive value (11%, 95% CI: 10-12%) and lower false positive rate (12%, 95% CI: 12-13%) compared to 4% and 37% for both ARISCAT and SPORC-1. The RESPIRE model also better predicted the established quality metrics for postoperative respiratory failure.

CONCLUSIONS

We developed a general-purpose, machine learning powered prediction tool with superior performance for research and quality-based definitions of postoperative respiratory failure.

Effects of individualised positive end-expiratory pressure titration on respiratory and haemodynamic parameters during the Trendelenburg position with pneumoperitoneum: A randomised crossover physiologic trial

BACKGROUND

The Trendelenburg position with pneumoperitoneum during surgery promotes dorsobasal atelectasis formation, which impairs respiratory mechanics and increases lung stress and strain. Positive end-expiratory pressure (PEEP) can reduce pulmonary inhomogeneities and preserve end-expiratory lung volume (EELV), resulting in decreased inspiratory strain and improved gas-exchange. The optimal intraoperative PEEP strategy is unclear.

OBJECTIVES

To compare the effects of individualised PEEP titration strategies on set PEEP levels and resulting transpulmonary pressures, respiratory mechanics, gas-exchange and haemodynamics during Trendelenburg position with pneumoperitoneum.

DESIGN

Prospective, randomised, crossover single-centre physiologic trial.

SETTING

University hospital.

PATIENTS

Thirty-six patients receiving robot-assisted laparoscopic radical prostatectomy.

INTERVENTIONS

Randomised sequence of three different PEEP strategies: standard PEEP level of 5 cmH 2 O (PEEP 5 ), PEEP titration targeting a minimal driving pressure (PEEP ΔP ) and oesophageal pressure-guided PEEP titration (PEEP Poeso ) targeting an end-expiratory transpulmonary pressure ( PTP ) of 0 cmH 2 O.

MAIN OUTCOME MEASURES

The primary endpoint was the PEEP level when set according to PEEP ΔP and PEEP Poeso compared with PEEP of 5 cmH 2 O. Secondary endpoints were respiratory mechanics, lung volumes, gas-exchange and haemodynamic parameters.

RESULTS

PEEP levels differed between PEEP ΔP , PEEP Poeso and PEEP5 (18.0 [16.0 to 18.0] vs. 20.0 [18.0 to 24.0]vs. 5.0 [5.0 to 5.0] cmH 2 O; P  < 0.001 each). End-expiratory PTP and lung volume were lower in PEEP ΔP compared with PEEP Poeso ( P  = 0.014 and P  < 0.001, respectively), but driving pressure, lung stress, as well as respiratory system and dynamic elastic power were minimised using PEEP ΔP ( P  < 0.001 each). PEEP ΔP and PEEP Poeso improved gas-exchange, but PEEP Poeso resulted in lower cardiac output compared with PEEP 5 and PEEP ΔP .

CONCLUSION

PEEP ΔP ameliorated the effects of Trendelenburg position with pneumoperitoneum during surgery on end-expiratory PTP and lung volume, decreased driving pressure and dynamic elastic power, as well as improved gas-exchange while preserving cardiac output.

TRIAL REGISTRATION

German Clinical Trials Register (DRKS00028559, date of registration 2022/04/27). https://drks.de/search/en/trial/DRKS00028559.

Individualized PEEP without Recruitment Maneuvers Improves Intraoperative Oxygenation: A Randomized Controlled Study

Individualized positive end-expiratory pressure (PEEP) combined with recruitment maneuvers improves intraoperative oxygenation in individuals undergoing robot-assisted prostatectomy. However, whether electrical impedance tomography (EIT)-guided individualized PEEP without recruitment maneuvers can also improve intraoperative oxygenation is unknown. To test this, fifty-six male patients undergoing elective robot-assisted laparoscopic prostatectomy were randomly assigned to either individualized PEEP (Group PEEPIND, n = 28) or a control with a fixed PEEP of 5 cm H2O (Group PEEP5, n = 28). Individualized PEEP was guided by EIT after placing the patients in the Trendelenburg position and performing intraperitoneal insufflation. Patients in Group PEEPIND maintained individualized PEEP without intermittent recruitment maneuvers, and those in Group PEEP5 maintained a PEEP of 5 cm H2O intraoperatively. Both groups were extubated in a semi-sitting position once the extubation criteria were met. The primary outcome was arterial oxygen partial pressure (PaO2)/inspiratory oxygen fraction (FiO2) prior to extubation. Other outcomes included intraoperative driving pressure, plateau pressure and dynamic, respiratory system compliance, and the incidence of postoperative hypoxemia in the post-operative care unit (PACU). Our results showed that the intraoperative median for PEEPIND was 16 cm H2O (ranging from 12 to 18 cm H2O). EIT-guided PEEPIND was associated with higher PaO2/FiO2 before extubation compared to PEEP5 (71.6 ± 10.7 vs. 56.8 ± 14.1 kPa, p = 0.003). Improved oxygenation extended into the PACU with a lower incidence of postoperative hypoxemia (3.8% vs. 26.9%, p = 0.021). Additionally, PEEPIND was associated with lower driving pressures (12.0 ± 3.0 vs. 15.0 ± 4.4 cm H2O, p = 0.044) and better compliance (44.5 ± 12.8 vs. 33.6 ± 9.1 mL/cm H2O, p = 0.017). Our data indicated that individualized PEEP guided by EIT without intraoperative recruitment maneuvers also improved perioperative oxygenation in patients undergoing robot-assisted laparoscopic radical prostatectomy, which could benefit patients with the risk of intraoperative hemodynamic instability caused by recruitment maneuvers. Trial registration: China Clinical Trial Registration Center Identifier: ChiCTR2100053839. This study was registered on 1 December 2021. The first patient was recruited on 15 December 2021.

Perioperative Management of Heart Transplantation: A Clinical Review

In this clinical review, the authors summarize the perioperative management of heart transplant patients with a focus on hemodynamics, immunosuppressive strategies, hemostasis and hemorrage, and the prevention and treatment of infectious complications.

Optimal positive end-expiratory pressure titration of intraoperative mechanical ventilation in different operative positions of female patients under general anesthesia

Objective

This study aimed to compare the effectiveness and safety of different titrated methods used to determine individual positive end-expiratory pressure (PEEP) for intraoperative mechanical ventilation in female patients undergoing general anesthesia in different operative positions, and provide reference ranges of optimal PEEP values based on the titration.

Methods

A total of 123 female patients who underwent elective open abdominal surgery under general anesthesia were included in this study. After endotracheal intubation, patients' body position was adjusted to the supine position, Trendelenburg positions at 10° and 20° respectively. PEEP was titrated from 20 cmH2O to 4 cmH2O, decreasing by 2 cmH2O every 1 min. Electrical impedance tomography (EIT), hemodynamic and respiratory mechanics parameters were continuously monitored and recorded. Optimal PEEP values and reference ranges were respectively calculated based on optimal EIT parameters, mean arterial pressure (MAP), and lung dynamic compliance (Cdyn).

Results

EIT-guided optimal PEEP was found to have higher values than those of the MAP-guided and Cdyn-guided methods for all three body positions (P < 0.001), and it was observed to more significantly inhibit hemodynamics (P < 0.05). The variable coefficients of EIT-guided optimal PEEP values were smaller than those of the other two methods, and this technique could provide better ventilation uniformity for dorsal/ventral lung fields and better balance for pulmonary atelectasis/collapse. The 95% reference ranges of EIT-guided optimal PEEP values were 4.6-13.8 cmH2O, 7.0-15.0 cmH2O and 8.6-17.0 cmH2O for the supine position, Trendelenburg 10°, and Trendelenburg 20° positions, respectively.

Conclusion

EIT-guided optimal PEEP titration was found to be a superior method for lung protective ventilation in different operative positions under general anesthesia. The calculated reference ranges of PEEP values based on the EIT-guided method can be used as a reference for intraoperative mechanical ventilation.

Minimizing Lung Injury During Laparoscopy in Head-Down Tilt: A Physiological Cohort Study

BACKGROUND

Increased intra-abdominal pressure during laparoscopy induces atelectasis. Positive end-expiratory pressure (PEEP) can alleviate atelectasis but may cause hyperinflation. Cyclic opening of collapsed alveoli and hyperinflation can lead to ventilator-induced lung injury and postoperative pulmonary complications. We aimed to study the effect of PEEP on atelectasis, lung stress, and hyperinflation during laparoscopy in the head-down (Trendelenburg) position.

METHODS

An open-label, repeated-measures, interventional, physiological cohort trial was designed. All participants were recruited from a single tertiary Belgian university hospital. Twenty-three nonobese patients scheduled for laparoscopy in the Trendelenburg position were recruited.We applied a decremental PEEP protocol: 15 (high), 10 and 5 (low) cm H 2 O. Atelectasis was studied with the lung ultrasound score, the end-expiratory transpulmonary pressure, the arterial oxygen partial pressure to fraction of inspired oxygen concentration (P ao2 /Fi o2 ) ratio, and the dynamic respiratory system compliance. Global hyperinflation was evaluated by dead space volume, and regional ventilation was evaluated by lung ultrasound. Lung stress was estimated using the transpulmonary driving pressure and dynamic compliance. Data are reported as medians (25th-75th percentile).

RESULTS

At 15, 10, and 5 cm H 2 O PEEP, the respective measurements were: lung ultrasound scores (%) 11 (0-22), 27 (11-39), and 53 (42-61) ( P < .001); end-expiratory transpulmonary pressures (cm H 2 O) 0.9 (-0.6 to 1.7), -0.3 (-2.0 to 0.7), and -1.9 (-4.6 to -0.9) ( P < .001); P ao2 /Fi o2 ratios (mm Hg) 471 (435-538), 458 (410-537), and 431 (358-492) ( P < .001); dynamic respiratory system compliances (mL/cm H 2 O) 32 (26-36), 30 (25-34), and 27 (22-30) ( P < .001); driving pressures (cm H 2 O) 8.2 (7.5-9.5), 9.3 (8.5-11.1), and 11.0 (10.3-12.2) ( P < .001); and alveolar dead space ventilation fractions (%) 10 (9-12), 10 (9-12), and 9 (8-12) ( P = .23). The lung ultrasound score was similar between apical and basal lung regions at each PEEP level ( P = .76, .37, and .76, respectively).

CONCLUSIONS

Higher PEEP levels during laparoscopy in the head-down position facilitate lung-protective ventilation. Atelectasis and lung stress are reduced in the absence of global alveolar hyperinflation.

Effects of an open lung extubation strategy compared with a conventional extubation strategy on postoperative pulmonary complications after general anesthesia: a single-centre pilot randomized controlled trial

PURPOSE

Postoperative pulmonary complications (PPCs) are a common cause of morbidity. Postoperative atelectasis is thought to be a significant risk factor in their development. Recent imaging studies suggest that patients' extubation may result in similar postoperative atelectasis regardless of the intraoperative mechanical ventilation strategy used. In this pilot trial, we hypothesized that a study investigating the effects of an open lung extubation strategy compared with a conventional one on PPCs would be feasible.

METHODS

We conducted a pilot, single-centre, double-blinded randomized controlled trial. Adult patients at moderate to high risk of PPCs and scheduled for elective surgery were eligible. Patients were randomized to an open lung extubation strategy (semirecumbent position, fraction of inspired oxygen [FIO2] 50%, pressure support ventilation, unchanged positive end-expiratory pressure) or to a conventional extubation strategy (dorsal decubitus position, FIO2 100%, manual bag ventilation). The primary feasibility outcome was global protocol adherence while the primary exploratory efficacy outcome was PPCs.

RESULTS

We randomized 35 patients to the conventional extubation group and 34 to the open lung extubation group. We observed a global protocol adherence of 96% (95% confidence interval, 88 to 99), which was not different between groups. Eight PPCs occurred (two in the conventional extubation group vs six in the open lung extubation group). Less postoperative supplemental oxygen and better lung aeration were observed in the open lung extubation group.

CONCLUSIONS

In this single-centre pilot trial, we observed excellent feasibility. A multicentre pilot trial comparing the effect of an open lung extubation strategy with that of a conventional extubation strategy on the occurrence of PPCs is feasible.

STUDY REGISTRATION DATE

ClinicalTrials.gov (NCT04993001); registered 6 August 2021.

Impact of Lower Tidal Volumes During One-Lung Ventilation: A 2022 Update of the Meta-analysis of Randomized Controlled Trials

OBJECTIVES

To clarify the influence of lower tidal volume (4-7 mL/kg) compared with higher tidal volume (8-15 mL/kg) during one-lung ventilation (OLV) on gas exchange and postoperative clinical outcome.

DESIGN

Meta-analysis of randomized trials.

SETTING

Thoracic surgery.

PARTICIPANTS

Patients receiving OLV.

INTERVENTIONS

Lower tidal volume during OLV.

MEASUREMENTS AND MAIN RESULTS

Primary outcome was PaO2-to-the oxygen fraction (PaO2/FIO2) ratio at the end of the surgery, after the reinstitution of two-lung ventilation. Secondary endpoints included perioperative changes in PaO2/FIO2 ratio and carbon dioxide (PaCO2) tension, airway pressure, the incidence of postoperative pulmonary complications, arrhythmia, and length of hospital stay. Seventeen randomized controlled trials (1,463 patients) were selected. Overall analysis showed that the use of low tidal volume during OLV was associated with a significantly higher PaO2/FIO2 ratio 15 minutes after the start of OLV and at the end of surgery (mean difference 33.7 mmHg [p = 0.02] and mean difference 18.59 mmHg [p < 0.001], respectively). The low tidal volume also was associated with higher PaCO2 values 15 minutes and 60 minutes after the start of OLV and with lower airway pressure, which was maintained during two-lung ventilation after surgery. Moreover, the application of lower tidal volume was associated with fewer postoperative pulmonary complications (odds ratio 0.50; p < 0.001) and arrhythmias (odds ratio 0.58; p = 0.009), with no difference in length of hospital stay.

CONCLUSIONS

The use of lower tidal volume, a component of protective OLV, increases the PaO2/FIO2 ratio, reduces the incidence of postoperative pulmonary complications, and should be considered strongly in daily practice.

Intensity of one-lung ventilation and postoperative respiratory failure: A hospital registry study

BACKGROUND

Studies linked a high intensity of mechanical ventilation, measured as high mechanical power (MP) to postoperative respiratory failure (PRF) in the setting of two-lung ventilation. We investigated whether a higher MP during one-lung ventilation (OLV) is associated with PRF.

METHODS

In this registry-based study, adult patients who underwent general anesthesia with OLV for thoracic surgeries between 2006 and 2020 at a New England tertiary healthcare network were included. The association between MP during OLV and PRF (emergency non-invasive ventilation or reintubation within seven days) was assessed in a cohort weighted through a generalized propensity score conditional on a priori defined preoperative and intraoperative factors. Dominance of components of MP and intensity of OLV versus two-lung ventilation in predicting PRF was investigated.

RESULTS

Out of 878 included patients, 106 (12.1%) developed PRF. The median (IQR) MP during OLV was 9.8 J/min (7.5-11.8) and 8.3 J/min (6.6-10.2) in patients with and without PRF respectively. A higher MP during OLV was associated with PRF (ORadj 1.22 per 1 J/min increase; 95%CI 1.13-1.31; p < 0.001) and characterized by a U-shaped dose-response curve, with the lowest probability of PRF (7.5%) at 6.4 J/min. Dominance analysis of PRF predictors showed a stronger contribution of driving pressure over respiratory rate and tidal volume, the dynamic over the static component of MP, and MP during OLV over two-lung ventilation (contribution to Pseudo-R2: 0.017, 0.021, and 0.036, respectively).

CONCLUSION

A higher intensity of OLV, mainly driven by driving pressure, is dose-dependently associated with PRF and might constitute a target for mechanical ventilation.

Effect of individualized positive end-expiratory pressure based on electrical impedance tomography guidance on pulmonary ventilation distribution in patients who receive abdominal thermal perfusion chemotherapy

Background

Electrical impedance tomography (EIT) has been shown to be useful in guiding individual positive end-expiratory pressure titration for patients with mechanical ventilation. However, the appropriate positive end-expiratory pressure (PEEP) level and whether the individualized PEEP needs to be adjusted during long-term surgery (>6 h) were unknown. Meanwhile, the effect of individualized PEEP on the distribution of pulmonary ventilation in patients who receive abdominal thermoperfusion chemotherapy is unknown. The primary aim of this study was to observe the effect of EIT-guided PEEP on the distribution of pulmonary ventilation in patients undergoing cytoreductive surgery (CRS) combined with hot intraperitoneal chemotherapy (HIPEC). The secondary aim was to analyze their effect on postoperative pulmonary complications.

Methods

A total of 48 patients were recruited and randomly divided into two groups, with 24 patients in each group. For the control group (group A), PEEP was set at 5 cm H2O, while in the EIT group (group B), individual PEEP was titrated and adjusted every 2 h with EIT guidance. Ventilation distribution, respiratory/circulation parameters, and PPC incidence were compared between the two groups.

Results

The average individualized PEEP was 10.3 ± 1.5 cm H2O, 10.2 ± 1.6 cm H2O, 10.1 ± 1.8 cm H2O, and 9.7 ± 2.1 cm H2O at 5 min, 2 h, 4 h, and 6 h after tracheal intubation during CRS + HIPEC. Individualized PEEP was correlated with ventilation distribution in the regions of interest (ROI) 1 and ROI 3 at 4 h mechanical ventilation and ROI 1 at 6 h mechanical ventilation. The ventilation distribution under individualized PEEP was back-shifted for 6 h but moved to the control group's ventral side under PEEP 5 cm H2O. The respiratory and circulatory function indicators were both acceptable either under individualized PEEP or PEEP 5 cm H2O. The incidence of total PPCs was significantly lower under individualized PEEP (66.7%) than PEEP 5 cm H2O (37.5%) for patients with CRS + HIPEC.

Conclusion

The appropriate individualized PEEP was stable at approximately 10 cm H2O during 6 h for patients with CRS + HIPEC, along with better ventilation distribution and a lower total PPC incidence than the fixed PEEP of 5 cm H2O.Clinical trial registration: identifier ChiCTR1900023897.