Driving pressure-guided ventilation and postoperative pulmonary complications in thoracic surgery: a multicentre randomised clinical trial

Clinical practice of one-lung ventilation in mainland China: a nationwide questionnaire survey

BACKGROUND

Limited information is available regarding the application of lung-protective ventilation strategies during one-lung ventilation (OLV) across mainland China. A nationwide questionnaire survey was conducted to investigate this issue in current clinical practice.

METHODS

The survey covered various aspects, including respondent demographics, the establishment and maintenance of OLV, intraoperative monitoring standards, and complications associated with OLV.

RESULTS

Five hundred forty-three valid responses were collected from all provinces in mainland China. Volume control ventilation mode, 4 to 6 mL per kilogram of predictive body weight, pure oxygen inspiration, and a low-level positive end-expiratory pressure ≤ 5 cm H2O were the most popular ventilation parameters. The most common thresholds of intraoperative respiration monitoring were peripheral oxygen saturation (SpO2) of 90-94%, end-tidal CO2 of 45 to 55 mm Hg, and an airway pressure of 30 to 34 cm H2O. Recruitment maneuvers were traditionally performed by 94% of the respondents. Intraoperative hypoxemia and laryngeal injury were experienced by 75% and 51% of the respondents, respectively. The proportions of anesthesiologists who frequently experienced hypoxemia during OLV were 19%, 24%, and 7% for lung, cardiovascular, and esophageal surgeries, respectively. Up to 32% of respondents were reluctant to perform lung-protective ventilation strategies during OLV. Multiple regression analysis revealed that the volume-control ventilation mode and an SpO2 intervention threshold of < 85% were independent risk factors for hypoxemia during OLV in lung and cardiovascular surgeries. In esophageal surgery, working in a tier 2 hospital and using traditional ventilation strategies were independent risk factors for hypoxemia during OLV. Subgroup analysis revealed no significant difference in intraoperative hypoxemia during OLV between respondents who performed lung-protective ventilation strategies and those who did not.

CONCLUSIONS

Lung-protective ventilation strategies during OLV have been widely accepted in mainland China and are strongly recommended for esophageal surgery, particularly in tier 2 hospitals. Implementing volume control ventilation mode and early management of oxygen desaturation might prevent hypoxemia during OLV.

Lung protective ventilation guided by driving pressure improves pulmonary outcomes in heart transplantation

This study aimed to investigate whether driving pressure-guided ventilation can reduce postoperative pulmonary complications in patients who have undergone heart transplantation. Patients who underwent orthotopic heart transplantation were divided into two groups according to the perioperative ventilation strategy: (1) conventional lung-protective ventilation (group C) and (2) driving pressure-guided ventilation (group D). The primary outcome was the occurrence of postoperative pulmonary complications within 30 days of surgery. Univariate and multivariate logistic regression analyses were performed to evaluate the independent risk factors associated with postoperative pulmonary complications (PPCs). Compared with group C, patients in group D exhibited lower driving pressure. Oxygenation improved significantly in the early period after surgery in patients in group D. Group C exhibited a higher number of patients with postoperative pulmonary complications, especially respiratory infections and atelectasis. Patients in group D experienced a shorter duration of postoperative mechanical ventilation and a shorter stay in the intensive care unit. The conventional ventilation strategy, the high driving pressure level and the low PaO2 value at the end of the surgery were the independent risk factors for PPCs in heart transplantation. Compared with conventional lung-protective ventilation, driving pressure-guided ventilation was associated with improved pulmonary oxygenation and lower incidences of pulmonary complications among patients after heart transplantation.

Association of mechanical power and postoperative pulmonary complications among young children undergoing video-assisted thoracic surgery: A retrospective study

BACKGROUND

Previous studies have discussed the correlation between mechanical power (MP) and lung injury. However, evidence regarding the relationship between MP and postoperative pulmonary complications (PPCs) in children remains limited, specifically during one-lung ventilation (OLV).

OBJECTIVES

Propensity score matching was employed to generate low MP and high MP groups to verify the relationship between MP and PPCs. Multivariable logistic regression was performed to identify risk factors of PPCs in young children undergoing video-assisted thoracic surgery (VATS).

DESIGN

A retrospective study.

SETTING

Single-site tertiary children's hospital.

PATIENTS

Children aged ≤2 years who underwent VATS between January 2018 and February 2023.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The incidence of PPCs.

RESULTS

Overall, 581 (median age, 6 months [interquartile range: 5-9.24 months]) children were enrolled. The median [interquartile range] MP during OLV were 2.17 [1.84 to 2.64) J min-1. One hundred and nine (18.76%) children developed PPCs. MP decreased modestly during the study period (2.63 to 1.99 J min-1; P < 0.0001). In the propensity score matched cohort for MP (221 matched pairs), MP (median MP 2.63 vs. 1.84 J min-1) was not associated with a reduction in PPCs (adjusted odds ratio, 1.43; 95% CI, 0.87 to 2.37; P = 0.16). In the propensity score matched cohort for dynamic components of MP (139 matched pairs), dynamic components (mean 2.848 vs. 4.162 J min-1) was not associated with a reduction in PPCs (adjusted odds ratio, 1.62; 95% CI, 0.85 to 3.10; P  = 0.15).The multiple logistic analysis revealed PPCs within 7 days of surgery were associated with male gender, OLV duration >90 min, less surgeon's experience and lower positive end-expiratory pressure (PEEP) value.

CONCLUSIONS

MP and dynamic components were not associated with PPCs in young children undergoing VATS, whereas PPCs were associated with male gender, OLV duration >90 min, less surgeon's experience and lower PEEP value.

TRIAL REGISTRATION

ChiCTR2300074649.

Lung-protective ventilation and postoperative pulmonary complications during pulmonary resection in children: A prospective, single-centre, randomised controlled trial

BACKGROUND

Children are more susceptible to postoperative pulmonary complications (PPCs) due to their smaller functional residual capacity and higher closing volume; however, lung-protective ventilation (LPV) in children requiring one-lung ventilation (OLV) has been relatively underexplored.

OBJECTIVES

To evaluate the effects of LPV and driving pressure-guided ventilation on PPCs in children with OLV.

DESIGN

Randomised, controlled, double-blind study.

SETTING

Single-site tertiary hospital, 6 May 2022 to 31 August 2023.

PATIENTS

213 children aged < 6 years, planned for lung resection secondary to congenital cystic adenomatoid malformation.

INTERVENTIONS

Children were randomly assigned to LPV ( n  = 142) or control ( n  = 71) groups. Children in LPV group were randomly assigned to either driving pressure group ( n  = 70) receiving individualised positive end-expiratory pressure (PEEP) to deliver the lowest driving pressure or to conventional protective ventilation group ( n  = 72) with fixed PEEP of 5 cmH 2 O.

MAIN OUTCOME MEASURES

The primary outcome was the incidence of PPCs within 7 days after surgery. Secondary outcomes were pulmonary mechanics, oxygenation and mechanical power.

RESULTS

The incidence of PPCs did not differ between the LPV (24/142, 16.9%) and the control groups (15/71, 21.1%) ( P  = 0.45). The driving pressure was lower in the driving pressure group than in the 5 cmH 2 O PEEP group (15 vs. 17 cmH 2 O; P   =  0.001). Lung compliance and oxygenation were higher while the dynamic component of mechanical power was lower in the driving pressure group than in the 5 cmH 2 O PEEP group. The incidence of PPCs did not differ between the driving pressure (11/70, 15.7%) and the 5 cmH 2 O PEEP groups (13/72, 18.1%) ( P   =  0.71).

CONCLUSIONS

LPV did not decrease the occurrence of PPCs compared to non-protective ventilation. Although lung compliance and oxygenation were higher in the driving pressure group than in the 5 cmH 2 O PEEP group, these benefits did not translate into significant reductions in PPCs. However, the study is limited by a small sample size, which may affect the interpretation of the results. Future research with larger sample sizes is necessary to confirm these findings.

TRIAL REGISTRATION

ChiCTR2200059270.

Association between thoracic epidural anesthesia and driving pressure in adult patients undergoing elective major upper abdominal surgery: a randomized controlled trial

BACKGROUND

Thoracic epidural anesthesia (TEA) is associated with a knowledge gap regarding its mechanisms in lung protection and reduction of postoperative pulmonary complications (PPCs). Driving pressure (ΔP), an alternative indicator of alveolar strain, is closely linked to reduced PPCs with lower ΔP values. We aim to investigate whether TEA contributes to lung protection by lowering ΔP during mechanical ventilation.

METHODS

In this prospective, randomized, patient and evaluator-blinded parallel study, adult patients scheduled for elective major upper abdominal surgery were assigned to either the TEA group with combined thoracic epidural anesthesia and general anesthesia (TEA-GA) (n = 30) or the control group with only general anesthesia (GA) (n = 30).

MEASUREMENTS

The primary outcome was the minimum ΔP determined based on positive end-expiratory pressure (PEEP) after intubation. Secondary outcomes included the incidence of PPCs within seven days, the minimum ΔP at various time points, blood gas analysis, intensive care unit (ICU) admission rates, length of hospital stay, and 30-day mortality rate.

RESULTS

The TEA group had a significantly lower minimum ΔP titrated based on PEEP compared to the control group (11.23 ± 2.19 cmH2O vs. 12.67 ± 2.70 cmH2O; P = 0.028). Multivariate linear regression analysis showed that intraoperative TEA application (compared with its absence; unstandardized beta coefficient (B) = -1.289; P = 0.008) significantly correlated with ΔP. The incidence of PPCs did not differ significantly between the two groups (8 of 30 [26.7%] vs. 12 of 30 [40%]; P = 0.273), but the incidence of atelectasis in the TEA group was significantly lower than in the control group (5 of 30 [16.7%] vs. 12 of 30 [40.7%]; P = 0.012). Multivariate logistic regression analysis indicated that ΔP was the only variable significantly associated with PPCs (Adjusted Odds Ratio [OR] = 2.190; 95% Confidence Interval [CI]: 1.300 to 3.689; P = 0.003).

CONCLUSION

Compared to GA, TEA-GA can reduce intraoperative ΔP in patients undergoing major upper abdominal surgery, especially those undergoing laparoscopic surgery. However, compared to GA combined with ΔP-guided ventilation, TEA-GA combined with ΔP-guided ventilation does not reduce the risk of PPCs. There was no significant difference in the total use of various vasoactive drugs between the two groups.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Trial Registry (registration number ChiCTR2300068778 date of registration February 28, 2023).

The association between intraoperative low driving pressure ventilation and perioperative healthcare-associated costs: A retrospective multicenter cohort study

STUDY OBJECTIVE

A low dynamic driving pressure during mechanical ventilation for general anesthesia has been associated with a lower risk of postoperative respiratory complications (PRC), a key driver of healthcare costs. It is, however, unclear whether maintaining low driving pressure is clinically relevant to measure and contain costs. We hypothesized that a lower dynamic driving pressure is associated with lower costs.

DESIGN

Multicenter retrospective cohort study.

SETTING

Two academic healthcare networks in New York and Massachusetts, USA.

PATIENTS

46,715 adult surgical patients undergoing general anesthesia for non-ambulatory (inpatient and same-day admission) surgery between 2016 and 2021.

INTERVENTIONS

The primary exposure was the median intraoperative dynamic driving pressure.

MEASUREMENTS

The primary outcome was direct perioperative healthcare-associated costs, which were matched with data from the Healthcare Cost and Utilization Project-National Inpatient Sample (HCUP-NIS) to report absolute differences in total costs in United States Dollars (US$). We assessed effect modification by patients' baseline risk of PRC (score for prediction of postoperative respiratory complications [SPORC] ≥ 7) and effect mediation by rates of PRC (including post-extubation saturation < 90%, re-intubation or non-invasive ventilation within 7 days) and other major complications.

MAIN RESULTS

The median intraoperative dynamic driving pressure was 17.2cmH2O (IQR 14.0-21.3cmH2O). In adjusted analyses, every 5cmH2O reduction in dynamic driving pressure was associated with a decrease of -0.7% in direct perioperative healthcare-associated costs (95%CI -1.3 to -0.1%; p = 0.020). When a dynamic driving pressure below 15cmH2O was maintained, -US$340 lower total perioperative healthcare-associated costs were observed (95%CI -US$546 to -US$132; p = 0.001). This association was limited to patients at high baseline risk of PRC (n = 4059; -US$1755;97.5%CI -US$2495 to -US$986; p < 0.001), where lower risks of PRC and other major complications mediated 10.7% and 7.2% of this association (p < 0.001 and p = 0.015, respectively).

CONCLUSIONS

Intraoperative mechanical ventilation targeting low dynamic driving pressures could be a relevant measure to reduce perioperative healthcare-associated costs in high-risk patients.

Individualized positive end-expiratory pressure in laparoscopic surgery: a randomized controlled trial

BACKGROUND

The reduction in functional residual capacity (FRC) is a significant pathological factor in the development of postoperative pulmonary complications. Appropriate positive end-expiratory pressure (PEEP) is critical to preserve FRC during mechanical ventilation. Our previous study suggests that using driving pressure-guided PEEP can reduce postoperative pulmonary complications. In this study, we hypothesize that individualized PEEP can increase immediate postoperative FRC and improve lung ventilation.

METHODS

This single-centered, randomized controlled trial included a total of 91 patients scheduled for laparoscopic surgery for colorectal carcinoma. Patients were randomly assigned to receive individualized PEEP guided by minimum driving pressure or a fixed PEEP of six cmH2O. The primary outcome was postoperative FRC. Secondary outcomes included the incidence of postoperative pulmonary complications, postoperative Oxygenation Index, alveolar-arterial oxygen tension difference (PA-aO2), intrapulmonary shunt (QS/QT), and Respiratory Index, as well as lung ventilation measured by electrical impedance tomography.

RESULTS

The median value of PEEP in the individualized group was 14 cmH2O, with an interquartile range of 12-14 cmH2O. The postoperative FRC was significantly higher in the individualized PEEP group than that in the PEEP six cmH2O group (32.8 [12.8] vs. 25.0 [12.6] mL/kg, P=0.004). Patients receiving driving pressure-guided PEEP also had significantly higher Oxygenation Index, better ventilation distribution, and lower PA-aO2, QS/QT, and Respiratory Index.

CONCLUSIONS

Driving pressure-guided PEEP can preserve postoperative FRC and provide better ventilation and oxygenation for patients undergoing laparoscopic colorectal surgery.

Development and validation of a nomogram for predicting pulmonary complications in elderly patients undergoing thoracic surgery

BACKGROUND

Postoperative pulmonary complications (PPCs) remain a prevalent concern among elderly patients undergoing surgery, with a notably higher incidence observed in elderly patients undergoing thoracic surgery. This study aimed to develop a nomogram to predict the risk of PPCs in this population.

METHODS

A total of 2963 elderly patients who underwent thoracic surgery were enrolled and randomly divided into a training cohort (80%, n = 2369) or a validation cohort (20%, n = 593). Univariate and multivariate logistic regression analyses were conducted to identify risk factors for PPCs, and a nomogram was developed based on the findings from the training cohort. The validation cohort was used to validate the model. The predictive accuracy of the model was evaluated by receiver operating characteristic (ROC) curve, area under ROC (AUC), calibration curve, and decision curve analysis (DCA).

RESULTS

A total of 918 (31.0%) patients reported PPCs. Nine independent risk factors for PPCs were identified: preoperative presence of chronic obstructive pulmonary disease (COPD), elevated leukocyte count, higher partial pressure of arterial carbon dioxide (PaCO2) level, surgical site, thoracotomy, intraoperative hypotension, blood loss > 100 mL, surgery duration > 180 min, and malignant tumor. The AUC value for the training cohort was 0.739 (95% CI: 0.719-0.762), and it was 0.703 for the validation cohort (95% CI: 0.657-0.749). The P-values for the Hosmer-Lemeshow test were 0.633 and 0.144 for the training and validation cohorts, respectively, indicating a notable calibration curve fit. The DCA curve indicated that the nomogram could be applied clinically if the risk threshold was between 12% and 84%, which was found to be between 8% and 82% in the validation cohort.

CONCLUSION

This study highlighted the pressing need for early detection of PPCs in elderly patients undergoing thoracic surgery. The nomogram exhibited promising predictive efficacy for PPCs in elderly patients undergoing thoracic surgery, enabling the identification of high-risk patients and consequently aiding in the implementation of preventive interventions.

Effects of lung protection ventilation strategies on postoperative pulmonary complications after noncardiac surgery: a network meta-analysis of randomized controlled trials

BACKGROUND

The purpose of this network meta-analysis was to assess the impact of different protective ventilatory strategies on postoperative pulmonary complications (PPCs).

METHODS

Several databases were searched for randomized controlled trials (RCTs) that were published before October 2023 in a network meta-analysis. We assessed the effect of different lung-protective ventilation strategies on the incidence of PPCs using Bayesian network meta-analysis.

RESULTS

We included 58 studies (11610 patients) in this meta-analysis. The network meta-analysis showed that low tidal volumes (LTVs) combined with iPEEP and recruitment manoeuvres (RM) was associated with significantly lower incidence of PPCs [HTVs: OR = 0.38, 95%CrI (0.19, 0.75), LTVs: OR = 0.33, 95%CrI (0.12, 0.82)], postoperative atelectasis[HTVs: OR = 0.2, 95%CrI (0.08, 0.48), LTVs: OR = 0.47, 95%CrI (0.11, 0.93)], and pneumonia[HTVs: OR = 0.22, 95%CrI (0.09, 0.48), LTVs: OR = 0.27, 95%CrI (0.08,0.89)] than was High tidal volumes (HTVs) or LTVs. LTVs combined with medium-to-high PEEP and RM were associated with significantly lower incidence of postoperative atelectasis, and pneumonia.

CONCLUSION

LTVs combined with iPEEP and RM decreased the incidence of PPCs, postoperative atelectasis, and pneumonia in noncardiac surgery patients. Individual PEEP-guided ventilation was the optimal lung protection ventilation strategy. The quality of evidence is moderate.

TRIAL REGISTRATION

PROSPERO identifier CRD42023399485.

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 ventilation guided by driving pressure optimizes local pulmonary biomechanics in an ovine model

Mechanical ventilation exposes the lung to injurious stresses and strains that can negatively affect clinical outcomes in acute respiratory distress syndrome or cause pulmonary complications after general anesthesia. Excess global lung strain, estimated as increased respiratory system driving pressure, is associated with mortality related to mechanical ventilation. The role of small-dimension biomechanical factors underlying this association and their spatial heterogeneity within the lung are currently unknown. Using four-dimensional computed tomography with a voxel resolution of 2.4 cubic millimeters and a multiresolution convolutional neural network for whole-lung image segmentation, we dynamically measured voxel-wise lung inflation and tidal parenchymal strains. Healthy or injured ovine lungs were evaluated as the mechanical ventilation positive end-expiratory pressure (PEEP) was titrated from 20 to 2 centimeters of water. The PEEP of minimal driving pressure (PEEPDP) optimized local lung biomechanics. We observed a greater rate of change in nonaerated lung mass with respect to PEEP below PEEPDP compared with PEEP values above this threshold. PEEPDP similarly characterized a breaking point in the relationships between PEEP and SD of local tidal parenchymal strain, the 95th percentile of local strains, and the magnitude of tidal overdistension. These findings advance the understanding of lung collapse, tidal overdistension, and strain heterogeneity as local triggers of ventilator-induced lung injury in large-animal lungs similar to those of humans and could inform the clinical management of mechanical ventilation to improve local lung biomechanics.

Effect of flow-optimized pressure control ventilation-volume guaranteed (PCV-VG) on postoperative pulmonary complications: a consort study

BACKGROUND

Postoperative pulmonary complications (PPCs) after one-lung ventilation (OLV) significantly impact patient prognosis and quality of life.

OBJECTIVE

To study the impact of an optimal inspiratory flow rate on PPCs in thoracic surgery patients.

METHODS

One hundred eight elective thoracic surgery patients were randomly assigned to 2 groups in this consort study (control group: n = 53 with a fixed inspiratory expiratory ratio of 1:2; and experimental group [flow rate optimization group]: n = 55). Measurements of Ppeak, Pplat, PETCO2, lung dynamic compliance (Cdyn), respiratory rate, and oxygen concentration were obtained at the following specific time points: immediately after intubation (T0); immediately after starting OLV (T1); 30 min after OLV (T2); and 10 min after 2-lung ventilation (T4). The PaO2:FiO2 ratio was measured using blood gas analysis 30 min after initiating one-lung breathing (T2) and immediately when OLV ended (T3). The lung ultrasound score (LUS) was assessed following anesthesia and resuscitation (T5). The occurrence of atelectasis was documented immediately after the surgery. PPCs occurrences were noted 3 days after surgery.

RESULTS

The treatment group had a significantly lower total prevalence of PPCs compared to the control group (3.64% vs. 16.98%; P = 0.022). There were no notable variations in peak airway pressure, airway plateau pressure, dynamic lung compliance, PETCO2, respiratory rate, and oxygen concentration between the two groups during intubation (T0). Dynamic lung compliance and the oxygenation index were significantly increased at T1, T2, and T4 (P < 0.05), whereas the CRP level and number of inflammatory cells decreased dramatically (P < 0.05).

CONCLUSION

Optimizing inspiratory flow rate and utilizing pressure control ventilation -volume guaranteed (PCV-VG) mode can decrease PPCs and enhance lung dynamic compliance in OLV patients.

Effects of Positive End-expiratory Pressure on Pulmonary Perfusion Distribution and Intrapulmonary Shunt during One-lung Ventilation in Pigs: A Randomized Crossover Study

BACKGROUND

During one-lung ventilation (OLV), positive end-expiratory pressure (PEEP) can improve lung aeration but might overdistend lung units and increase intrapulmonary shunt. The authors hypothesized that higher PEEP shifts pulmonary perfusion from the ventilated to the nonventilated lung, resulting in a U-shaped relationship with intrapulmonary shunt during OLV.

METHODS

In nine anesthetized female pigs, a thoracotomy was performed and intravenous lipopolysaccharide infused to mimic the inflammatory response of thoracic surgery. Animals underwent OLV in supine position with PEEP of 0 cm H2O, 5 cm H2O, titrated to best respiratory system compliance, and 15 cm H2O (PEEP0, PEEP5, PEEPtitr, and PEEP15, respectively, 45 min each, Latin square sequence). Respiratory, hemodynamic, and gas exchange variables were measured. The distributions of perfusion and ventilation were determined by IV fluorescent microspheres and computed tomography, respectively.

RESULTS

Compared to two-lung ventilation, the driving pressure increased with OLV, irrespective of the PEEP level. During OLV, cardiac output was lower at PEEP15 (5.5 ± 1.5 l/min) than PEEP0 (7.6 ± 3 l/min) and PEEP5 (7.4 ± 2.9 l/min; P = 0.004), while the intrapulmonary shunt was highest at PEEP0 (PEEP0: 48.1% ± 14.4%; PEEP5: 42.4% ± 14.8%; PEEPtitr: 37.8% ± 11.0%; PEEP15: 39.0% ± 10.7%; P = 0.027). The relative perfusion of the ventilated lung did not differ among PEEP levels (PEEP0: 65.0% ± 10.6%; PEEP5: 68.7% ± 8.7%; PEEPtitr: 68.2% ± 10.5%; PEEP15: 58.4% ± 12.8%; P = 0.096), but the centers of relative perfusion and ventilation in the ventilated lung shifted from ventral to dorsal and from cranial to caudal zones with increasing PEEP.

CONCLUSIONS

In this experimental model of thoracic surgery, higher PEEP during OLV did not shift the perfusion from the ventilated to the nonventilated lung, thus not increasing intrapulmonary shunt.

EDITOR’S PERSPECTIVE

Utilising intraoperative respiratory dynamic features for developing and validating an explainable machine learning model for postoperative pulmonary complications

BACKGROUND

Timely detection of modifiable risk factors for postoperative pulmonary complications (PPCs) could inform ventilation strategies that attenuate lung injury. We sought to develop, validate, and internally test machine learning models that use intraoperative respiratory features to predict PPCs.

METHODS

We analysed perioperative data from a cohort comprising patients aged 65 yr and older at an academic medical centre from 2019 to 2023. Two linear and four nonlinear learning models were developed and compared with the current gold-standard risk assessment tool ARISCAT (Assess Respiratory Risk in Surgical Patients in Catalonia Tool). The Shapley additive explanation of artificial intelligence was utilised to interpret feature importance and interactions.

RESULTS

Perioperative data were obtained from 10 284 patients who underwent 10 484 operations (mean age [range] 71 [65-98] yr; 42% female). An optimised XGBoost model that used preoperative variables and intraoperative respiratory variables had area under the receiver operating characteristic curves (AUROCs) of 0.878 (0.866-0.891) and 0.881 (0.879-0.883) in the validation and prospective cohorts, respectively. These models outperformed ARISCAT (AUROC: 0.496-0.533). The intraoperative dynamic features of respiratory dynamic system compliance, mechanical power, and driving pressure were identified as key modifiable contributors to PPCs. A simplified model based on XGBoost including 20 variables generated an AUROC of 0.864 (0.852-0.875) in an internal testing cohort. This has been developed into a web-based tool for further external validation (https://aorm.wchscu.cn/).

CONCLUSIONS

These findings suggest that real-time identification of surgical patients' risk of postoperative pulmonary complications could help personalise intraoperative ventilatory strategies and reduce postoperative pulmonary complications.

Association of Mechanical Energy and Power with Postoperative Pulmonary Complications in Lung Resection Surgery: A Post Hoc Analysis of Randomized Clinical Trial Data

BACKGROUND

Mechanical power (MP), the rate of mechanical energy (ME) delivery, is a recently introduced unifying ventilator parameter consisting of tidal volume, airway pressures, and respiratory rates, which predicts pulmonary complications in several clinical contexts. However, ME has not been previously studied in the perioperative context, and neither parameter has been studied in the context of thoracic surgery utilizing one-lung ventilation.

METHODS

The relationships between ME variables and postoperative pulmonary complications were evaluated in this post hoc analysis of data from a multicenter randomized clinical trial of lung resection surgery conducted between 2020 and 2021 (n = 1,170). Time-weighted average MP and ME (the area under the MP time curve) were obtained for individual patients. The primary analysis was the association of time-weighted average MP and ME with pulmonary complications within 7 postoperative days. Multivariable logistic regression was performed to examine the relationships between energy variables and the primary outcome.

RESULTS

In 1,055 patients analyzed, pulmonary complications occurred in 41% (431 of 1,055). The median (interquartile ranges) ME and time-weighted average MP in patients who developed postoperative pulmonary complications versus those who did not were 1,146 (811 to 1,530) J versus 924 (730 to 1,240) J (P < 0.001), and 6.9 (5.5 to 8.7) J/min versus 6.7 (5.2 to 8.5) J/min (P = 0.091), respectively. ME was independently associated with postoperative pulmonary complications (ORadjusted, 1.44 [95% CI, 1.16 to 1.80]; P = 0.001). However, the association between time-weighted average MP and postoperative pulmonary complications was time-dependent, and time-weighted average MP was significantly associated with postoperative pulmonary complications in cases utilizing longer periods of mechanical ventilation (210 min or greater; ORadjusted, 1.46 [95% CI, 1.11 to 1.93]; P = 0.007). Normalization of ME and time-weighted average MP either to predicted body weight or to respiratory system compliance did not alter these associations.

CONCLUSIONS

ME and, in cases requiring longer periods of mechanical ventilation, MP were independently associated with postoperative pulmonary complications in thoracic surgery.

EDITOR’S PERSPECTIVE

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.

Update on guidelines and recommendations for enhanced recovery after thoracic surgery

PURPOSE OF REVIEW

Enhanced recovery after thoracic surgery (ERATS) has continued its growth in popularity over the past few years, and evidence for its utility is catching up to other specialties. This review will present and examine some of that accumulated evidence since guidelines sponsored by the Enhanced Recovery after Surgery (ERAS) Society and the European Society of Thoracic Surgeons (ESTS) were first published in 2019.

RECENT FINDINGS

The ERAS/ESTS guidelines published in 2019 have not been updated, but new studies have been done and new data has been published regarding some of the individual components of the guidelines as they relate to thoracic and lung resection surgery. While there is still not a consensus on many of these issues, the volume of available evidence is becoming more robust, some of which will be incorporated into this review.

SUMMARY

The continued accumulation of data and evidence for the benefits of enhanced recovery techniques in thoracic and lung resection surgery will provide the thoracic anesthesiologist with guidance on how to best care for these patients before, during, and after surgery. The data from these studies will also help to elucidate which components of ERAS protocols are the most beneficial, and which components perhaps do not provide as much benefit as previously thought.

Regional ventilation distribution before and after laparoscopic lung parenchymal resection

Objective.The aim of the present study was to evaluate the influence of one-sided pulmonary nodule and tumour on ventilation distribution pre- and post- partial lung resection.Approach.A total of 40 consecutive patients scheduled for laparoscopic lung parenchymal resection were included. Ventilation distribution was measured with electrical impedance tomography (EIT) in supine and surgery lateral positions 72 h before surgery (T1) and 48 h after extubation (T2). Left lung to global ventilation ratio (Fl), the global inhomogeneity index (GI), standard deviation of regional ventilation delay (RVDSD) and pendelluft amplitude (Apendelluft) were calculated to assess the spatial and temporal ventilation distribution.Main results.After surgery (T2), ventilation at the operated chest sides generally deteriorated compared to T1 as expected. For right-side resection, the differences were significant at both supine and left lateral positions (p< 0.001). The change of RVDSDwas in general more heterogeneous. For left-side resection, RVDSDwas worse at T2 compared to T1 at left lateral position (p= 0.002). The other EIT-based parameters showed no significant differences between the two time points. No significant differences were observed between supine and lateral positions for the same time points respectively.Significance.In the present study, we found that the surgery side influenced the ventilation distribution. When the resection was performed on the right lung, the postoperative ipsilateral ventilation was reduced and the right lung ratio fell significantly. When the resection was on the left lung, the ventilation delay was significantly increased.

The Year in Thoracic Anesthesia: Selected Highlights from 2022

This article reviews research highlights in the field of thoracic anesthesia. The highlights of this year included new developments in the preoperative assessment and prehabilitation of patients requiring thoracic surgery, updates on the use of devices for one-lung ventilation (OLV) in adults and children, updates on the anesthetic and postoperative management of these patients, including protective OLV ventilation, the use of opioid-sparing techniques and regional anesthesia, and outcomes using enhanced recovery after surgery, as well as the use of expanding indications for extracorporeal membrane oxygenation, specialized anesthetic techniques for airway surgery, and nonintubated video-assisted thoracic surgery.

One-Lung Ventilation and Postoperative Pulmonary Complications After Major Lung Resection Surgery. A Multicenter Randomized Controlled Trial

OBJECTIVES

The effect of one-lung ventilation (OLV) strategy based on low tidal volume (TV), application of positive end-expiratory pressure (PEEP), and alveolar recruitment maneuvers (ARM) to reduce postoperative acute respiratory distress syndrome (ARDS) and pulmonary complications (PPCs) compared with higher TV without PEEP and ARM strategy in adult patients undergoing lobectomy or pneumonectomy has not been well established.

DESIGN

Multicenter, randomized, single-blind, controlled trial.

SETTING

Sixteen Italian hospitals.

PARTICIPANTS

A total of 880 patients undergoing elective major lung resection.

INTERVENTIONS

Patients were randomized to receive lower tidal volume (LTV group: 4 mL/kg predicted body weight, PEEP of 5 cmH2O, and ARMs) or higher tidal volume (HTL group: 6 mL/kg predicted body weight, no PEEP, and no ARMs). After OLV, until extubation, both groups were ventilated using a tidal volume of 8 mL/kg and a PEEP value of 5 cmH2O. The primary outcome was the incidence of in-hospital ARDS. Secondary outcomes were the in-hospital rate of PPCs, major cardiovascular events, unplanned intensive care unit (ICU) admission, in-hospital mortality, ICU length of stay, and in-hospital length of stay.

MEASUREMENTS AND MAIN RESULTS

ARDS occurred in 3 of 438 patients (0.7%, 95% CI 0.1-2.0) and in 1 of 442 patients (0.2%, 95% CI 0-1.4) in the LTV and HTV group, respectively (Risk ratio: 3.03 95% CI 0.32-29, p = 0.372). Pulmonary complications occurred in 125 of 438 patients (28.5%, 95% CI 24.5-32.9) and in 136 of 442 patients (30.8%, 95% CI 26.6-35.2) in the LTV and HTV group, respectively (risk ratio: 0.93, 95% CI 0.76-1.14, p = 0.507). The incidence of major complications, in-hospital mortality, and unplanned ICU admission, ICU and in-hospital length of stay were comparable in both groups.

CONCLUSIONS

In conclusion, among adult patients undergoing elective lung resection, an OLV with lower tidal volume, PEEP 5 cmH2O, and ARMs and a higher tidal volume strategy resulted in low ARDS incidence and comparable postoperative complications, in-hospital length of stay, and mortality.

Association of mechanical power during one-lung ventilation and post-operative pulmonary complications among patients undergoing lobectomy: a protocol for a prospective cohort study

The association of intra-operative mechanical power (MP) with post-operative pulmonary complications (PPCs) has been described before, but it is uncertain whether the potential inherent bias can limit the use of this parameter, particularly in the context of one-lung ventilation. This single-center study aims to investigate the effect of MP during one-lung ventilation (OLV), and the risks of PPCs in patients undergoing thoracoscopic lobectomy. This prospective observational study is being conducted in an academic tertiary hospital in mainland China. Participants diagnosed with lung cancer, and aged 50 to 80 years are eligible. Video-assisted thoracoscopic surgery (VATS) lobectomy is performed for all patients. The primary outcome is the occurrence of PPCs over 5 consecutive days after the surgery, or until discharge from the hospital. Secondary outcomes include the composite conditions of PPCs, in-hospital stay, systematic inflammation tested by blood samples, and changes in aeration compartments in the ventilated lung as assessed by CT scans. We aim to evaluate the association of mean MP and the temporal patterns in the trend of MP during OLV with the occurrence of PPCs. A total of 120 patients will be enrolled in this study. The study protocol has received approval from the Ethics Committee of the affiliated hospital of Southwest Medical University, China (Reference number: KY2022162). The findings will be made available to the funder and researchers via scientific conferences and peer-reviewed publications. This controlled trial was approved by the Ethics Committee of Southwest Medical University(ChiCTR2200062173), and registered in the Chinese Clinical Trial Register website ( http://www.chictr.org.cn/edit.aspx?pid=172533&htm=4 , ChiCTR2200062173). A written consent was obtained from each patient.

Effect of driving pressure-guided positive end-expiratory pressure on postoperative pulmonary complications in patients undergoing laparoscopic or robotic surgery: a randomised controlled trial

BACKGROUND

Individualised positive end-expiratory pressure (PEEP) improves respiratory mechanics. However, whether PEEP reduces postoperative pulmonary complications (PPCs) remains unclear. We investigated whether driving pressure-guided PEEP reduces PPCs after laparoscopic/robotic abdominal surgery.

METHODS

This single-centre, randomised controlled trial enrolled patients at risk for PPCs undergoing laparoscopic or robotic lower abdominal surgery. The individualised group received driving pressure-guided PEEP, whereas the comparator group received 5 cm H2O fixed PEEP during surgery. Both groups received a tidal volume of 8 ml kg-1 ideal body weight. The primary outcome analysed per protocol was a composite of pulmonary complications (defined by pre-specified clinical and radiological criteria) within 7 postoperative days after surgery.

RESULTS

Some 384 patients (median age: 67 yr [inter-quartile range: 61-73]; 66 [18%] female) were randomised. Mean (standard deviation) PEEP in patients randomised to individualised PEEP (n=178) was 13.6 cm H2O (2.1). Individualised PEEP resulted in lower mean driving pressures (14.7 cm H2O [2.6]), compared with 185 patients randomised to standard PEEP (18.4 cm H2O [3.2]; mean difference: -3.7 cm H2O [95% confidence interval (CI): -4.3 to -3.1 cm H2O]; P<0.001). There was no difference in the incidence of pulmonary complications between individualised (25/178 [14.0%]) vs standard PEEP (36/185 [19.5%]; risk ratio [95% CI], 0.72 [0.45-1.15]; P=0.215). Pulmonary complications as a result of desaturation were less frequent in patients randomised to individualised PEEP (8/178 [4.5%], compared with standard PEEP (30/185 [16.2%], risk ratio [95% CI], 0.28 [0.13-0.59]; P=0.001).

CONCLUSIONS

Driving pressure-guided PEEP did not decrease the incidence of pulmonary complications within 7 days of laparoscopic or robotic lower abdominal surgery, although uncertainty remains given the lower than anticipated event rate for the primary outcome.

CLINICAL TRIAL REGISTRATION

KCT0004888 (http://cris.nih.go.kr, registration date: April 6, 2020).

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.

The effect of driving pressure-guided versus conventional mechanical ventilation strategy on pulmonary complications following on-pump cardiac surgery: A randomized clinical trial

STUDY OBJECTIVE

Postoperative pulmonary complications occur frequently and are associated with worse postoperative outcomes in cardiac surgical patients. The advantage of driving pressure-guided ventilation strategy in decreasing pulmonary complications remains to be definitively established. We aimed to investigate the effect of intraoperative driving pressure-guided ventilation strategy compared with conventional lung-protective ventilation on pulmonary complications following on-pump cardiac surgery.

DESIGN

Prospective, two-arm, randomized controlled trial.

SETTING

The West China university hospital in Sichuan, China.

PATIENTS

Adult patients who were scheduled for elective on-pump cardiac surgery were enrolled in the study.

INTERVENTIONS

Patients undergoing on-pump cardiac surgery were randomized to receive driving pressure-guided ventilation strategy based on positive end-expiratory pressure (PEEP) titration or conventional lung-protective ventilation strategy with fixed 5 cmH2O of PEEP.

MEASUREMENTS

The primary outcome of pulmonary complications (including acute respiratory distress syndrome, atelectasis, pneumonia, pleural effusion, and pneumothorax) within the first 7 postoperative days were prospectively identified. Secondary outcomes included pulmonary complication severity, ICU length of stay, and in-hospital and 30-day mortality.

MAIN RESULTS

Between August 2020 and July 2021, we enrolled 694 eligible patients who were included in the final analysis. Postoperative pulmonary complications occurred in 140 (40.3%) patients in the driving pressure group and 142 (40.9%) in the conventional group (relative risk, 0.99; 95% confidence interval, 0.82-1.18; P = 0.877). Intention-to-treat analysis showed no significant difference between study groups regarding the incidence of primary outcome. The driving pressure group had less atelectasis than the conventional group (11.5% vs 17.0%; relative risk, 0.68; 95% confidence interval, 0.47-0.98; P = 0.039). Secondary outcomes did not differ between groups.

CONCLUSION

Among patients who underwent on-pump cardiac surgery, the use of driving pressure-guided ventilation strategy did not reduce the risk of postoperative pulmonary complications when compared with conventional lung-protective ventilation strategy.

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.

Effect of intravenous vs. inhaled penehyclidine on respiratory mechanics in patients during one-lung ventilation for thoracoscopic surgery: a prospective, double-blind, randomised controlled trial

BACKGROUND

Minimising postoperative pulmonary complications (PPCs) after thoracic surgery is of utmost importance. A major factor contributing to PPCs is the driving pressure, which is determined by the ratio of tidal volume to lung compliance. Inhalation and intravenous administration of penehyclidine can improve lung compliance during intraoperative mechanical ventilation. Therefore, our study aimed to compare the efficacy of inhaled vs. intravenous penehyclidine during one-lung ventilation (OLV) in mitigating driving pressure and mechanical power among patients undergoing thoracic surgery.

METHODS

A double-blind, prospective, randomised study involving 176 patients scheduled for elective thoracic surgery was conducted. These patients were randomly divided into two groups, namely the penehyclidine inhalation group and the intravenous group before their surgery. Driving pressure was assessed at T1 (5 min after OLV), T2 (15 min after OLV), T3 (30 min after OLV), and T4 (45 min after OLV) in both groups. The primary outcome of this study was the composite measure of driving pressure during OLV. The area under the curve (AUC) of driving pressure from T1 to T4 was computed. Additionally, the secondary outcomes included mechanical power, lung compliance and the incidence of PPCs.

RESULTS

All 167 participants, 83 from the intravenous group and 84 from the inhalation group, completed the trial. The AUC of driving pressure for the intravenous group was 39.50 ± 9.42, while the inhalation group showed a value of 41.50 ± 8.03 (P = 0.138). The incidence of PPCs within 7 days after surgery was 27.7% in the intravenous group and 23.8% in the inhalation group (P = 0.564). No significant differences were observed in any of the other secondary outcomes between the two groups (all P > 0.05).

CONCLUSIONS

Our study found that among patients undergoing thoracoscopic surgery, no significant differences were observed in the driving pressure and mechanical power during OLV between those who received an intravenous injection of penehyclidine and those who inhaled it. Moreover, no significant difference was observed in the incidence of PPCs between the two groups.

Intraoperative Factors Modifying the Risk of Postoperative Pulmonary Complications After Living Donor Liver Transplantation

BACKGROUND

The relationship between intraoperative anesthetic management and postoperative pulmonary complications (PPCs) after liver transplantation is not fully understood. We aimed to determine the intraoperative contributors to PPC.

METHODS

The retrospectively collected cohort included 605 patients who underwent living donor liver transplantation. PPCs comprised respiratory failure, respiratory infection, pulmonary edema, atelectasis (at least moderate degree), pneumothorax, and pleural effusion (at least moderate degree). The presence and type of PPC were evaluated by 2 pulmonary physicians. Logistic regression analysis was performed to determine the association between perioperative variables and PPC risk.

RESULTS

Of the 605 patients, 318 patients (52.6%) developed 486 PPCs. Multivariable analysis demonstrated that PPC risk decreased with low tidal volume ventilation (odds ratio [OR] 0.62 [0.41-0.94], P  = 0.023) and increased with greater driving pressure at the end of surgery (OR 1.08 [1.01-1.14], P  = 0.018), prolonged hypotension (OR 1.85 [1.27-2.70], P  = 0.001), and blood albumin level ≤3.0 g/dL at the end of surgery (OR 2.43 [1.51-3.92], P  < 0.001). Survival probability at 3, 6, and 12 mo after transplantation was 91.2%, 89.6%, and 86.5%, respectively, in patients with PPCs and 98.3%, 96.5%, and 93.4%, respectively, in patients without PPCs (hazard ratio 2.2 [1.3-3.6], P  = 0.004). Graft survival probability at 3, 6, and 12 mo after transplantation was 89.3%, 87.1%, and 84.3%, respectively, in patients with PPCs and 97.6%, 95.8%, and 92.7%, respectively, in patients without PPCs (hazard ratio 2.3 [1.4-3.7], P  = 0.001).

CONCLUSIONS

We found that tidal volume, driving pressure, hypotension, and albumin level during living donor liver transplantation were significantly associated with PPC risk. These data may help determine patients at risk of PPC or develop an intraoperative lung-protective strategy for liver transplant recipients.

Performance Comparison of Pulmonary Risk Scoring Systems in Lung Resection

OBJECTIVE

To validate and compare the performance of different pulmonary risk scoring systems to predict postoperative pulmonary complications (PPCs) in lung resection surgery.

DESIGN

Retrospective cohort study SETTING: A historic single-center cohort of lung resection surgeries PARTICIPANTS: Adult patients undergoing lung resection surgery under 1-lung ventilation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The accuracy of the following pulmonary risk scoring systems were used to predict pulmonary complications: the ARISCAT (Assess respiratory RIsk in Surgical patients in CATalonia), the LAS VEGAS (Local Assessment of VEntilatory management during General Anesthesia for Surgery), the SPORC (Score for Prediction of Postoperative Respiratory Complications), and a recent thoracic-specific risk score, named CARDOT. Discrimination and calibration were assessed using the concordance (c) index and the intercept of LOESS (locally estimated scatterplot)-smoothed curves, respectively. Additional models were constructed that incorporated predicted postoperative forced expiratory volume (ppoFEV1) into each scoring system. Of the 2,104 patients undergoing lung surgery, 123 developed postoperative pulmonary complications (PPCs; 5.9%). All scoring systems had poor discriminatory power to predict PPCs (ARISCAT c-index 0.60, 95% confidence interval [CI] 0.55-0.65; LAS VEGAS c-index 0.68, 95% CI 0.63-0.73; SPORC c-index 0.63, 95% CI 0.59-0.68; CARDOT c-index 0.64, 95% CI 0.58-0.70), but the inclusion of ppoFEV1 slightly improved the performance of LAS VEGAS (c-index 0.70, 95% CI 0.66-0.75) and CARDOT (c-index 0.68, 95% CI 0.62-0.73). Analysis of calibration showed a slight overestimation when using ARISCAT (intercept -0.28) and LAS VEGAS (intercept -0.27).

CONCLUSIONS

None of the scoring systems appeared to have adequate discriminatory power to predict PPCs among patients undergoing lung resection. An alternative risk score is necessary to better predict patients at risk of PPCs after thoracic surgery.

Thoracic anaesthetic research: 90 years of sustained progress

Over the 90 years since the first description of one-lung ventilation, the practice of thoracic surgery and anaesthesia continues to develop. Minimally invasive surgical techniques are increasingly being used to minimise the surgical insult and facilitate improved outcomes. Challenging these outcomes, however, are parallel changes in patient characteristics with more older and sicker patients undergoing surgery. Thoracic anaesthesia as a speciality continues to respond to these challenges with evolution of practice and strong academic performance.

Do we have the 'power' to 'drive' down the incidence of pulmonary complications after thoracic surgery

The concept, mechanisms, and physical and physiological determinants of ventilator-induced lung injury, as well as the influence of lung-protective ventilation strategies, are novel paradigms of modern intensive care and perioperative medicine. Driving pressure and mechanical power have emerged as meaningful and modifiable targets with specific relevance to thoracic anaesthesia and one-lung ventilation. The relationship between these factors and postoperative pulmonary complications remains complex because of the methodological design and outcome selection. Larger observational studies are required to better understand the characteristics of driving pressure and power in current practice of thoracic anaesthesia in order to design future trials in high-risk thoracic populations at risk of acute lung injury.

A structured narrative review of clinical and experimental studies of the use of different positive end-expiratory pressure levels during thoracic surgery

OBJECTIVES

This study aimed to present a review on the general effects of different positive end-expiratory pressure (PEEP) levels during thoracic surgery by qualitatively categorizing the effects into detrimental, beneficial, and inconclusive.

DATA SOURCE

Literature search of Pubmed, CNKI, and Wanfang was made to find relative articles about PEEP levels during thoracic surgery. We used the following keywords as one-lung ventilation, PEEP, and thoracic surgery.

RESULTS

We divide the non-individualized PEEP value into five grades, that is, less than 5, 5, 5-10, 10, and more than 10 cmH₂ O, among which 5 cmH₂ O is the most commonly used in clinic at present to maintain alveolar dilatation and reduce the shunt fraction and the occurrence of atelectasis, whereas individualized PEEP, adjusted by test titration or imaging method to adapt to patients' personal characteristics, can effectively ameliorate intraoperative oxygenation and obtain optimal pulmonary compliance and better indexes relating to respiratory mechanics.

CONCLUSIONS

Available data suggest that PEEP might play an important role in one-lung ventilation, the understanding of which will help in exploring a simple and economical method to set the appropriate PEEP level.