Step-by-step clinical management of one-lung ventilation: continuing professional development

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.

Facilitating Lung Collapse for Thoracoscopic Surgery Utilizing Endobronchial Airway Occlusion Preceded by Pleurotomy and One-minute Suspension of Two-lung Ventilation

OBJECTIVES

To assess when and whether clamping the double-lumen endobronchial tube (DLT) limb of the non-ventilated lung is more conducive to a rapid and effective lung deflation than simply allowing the open limb of the DLT to communicate with the atmosphere.

DESIGN

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

SETTING

The trial was performed in a single institutional setting.

PARTICIPANTS

The participants were 60 patients undergoing elective video-assisted thoracoscopic surgery.

INTERVENTIONS

Patients were randomized to the open-clamp airway technique (OCAT group) or control group. Patients in the control group had one-lung ventilation initiated upon being placed in the lateral decubitus position. The OCAT group had two-lung ventilation maintained until the pleural cavity was opened with the introduction of a planned thoracoscopic access port to allow the operated lung to fall away from the chest wall. Thereafter, ventilation was suspended (temporarily ceased) for 1 minute before the DLT lumen of the isolated lung was clamped. The primary outcome of the trial was the time to complete lung collapse scored as determined from video clips taken during surgery. The secondary outcomes were (1) lung collapse score at 30 minutes after pleural incision, (2) surgeon satisfaction with surgery, and (3) intraoperative hypoxemia.

MEASUREMENTS AND MAIN RESULTS

The median time to reach complete lung collapse in the OCAT group was 10 minutes (odds ratio 10.0, 95% CI 6.3-13.7), which was much shorter than that of the control group (25 minutes [odds ratio 25.0, 95% CI 13.6-36.4]). The difference in complete lung collapse at 30 minutes between the 2 groups was significant (p < 0.001). The surgeon's satisfaction with surgery was higher in the OCAT group than in the control group (8.5 ± 0.2 vs 6.8 ± 0.2; p < 0.001). There was no difference regarding intraoperative hypoxemia.

CONCLUSIONS

Suspending ventilation of both DLT limbs for 1 minute after pleural cavity opening and then clamping the DLT lumen of the isolated lung resulted in a more rapid deflation of the surgical lung. This open-clamp airway technique is an effective technique for rapid surgical lung collapse during thoracoscopic surgery.

Thoracic paravertebral block for perioperative lung preservation during VATS pulmonary surgery: study protocol of a randomized clinical trial

BACKGROUND

Postoperative pulmonary complications (PPCs) extend the length of stay of patients and increase the perioperative mortality rate after video-assisted thoracoscopic (VATS) pulmonary surgery. Thoracic paravertebral block (TPVB) provides effective analgesia after VATS surgery; however, little is known about the effect of TPVB on the incidence of PPCs. The aim of this study is to determine whether TPVB combined with GA causes fewer PPCs and provides better perioperative lung protection in patients undergoing VATS pulmonary surgery than simple general anaesthesia.

METHODS

A total of 302 patients undergoing VATS pulmonary surgery will be randomly divided into two groups: the paravertebral block group (PV group) and the control group (C group). Patients in the PV group will receive TPVB: 15 ml of 0.5% ropivacaine will be administered to the T4 and T7 thoracic paravertebral spaces before general anaesthesia induction. Patients in the C group will not undergo the intervention. Both groups of patients will be subjected to a protective ventilation strategy during the operation. Perioperative protective mechanical ventilation and standard fluid management will be applied in both groups. Patient-controlled intravenous analgesia is used for postoperative analgesia. The primary endpoint is a composite outcome of PPCs within 7 days after surgery. Secondary endpoints include blood gas analysis, postoperative lung ultrasound score, NRS score, QoR-15 score, hospitalization-related indicators and long-term prognosis indicators.

DISCUSSION

This study will better evaluate the impact of TPVB on the incidence of PPCs and the long-term prognosis in patients undergoing VATS lobectomy/segmentectomy. The results may provide clinical evidence for optimizing perioperative lung protection strategies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05922449 . Registered on June 25, 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.

Tidal volume challenge-induced hemodynamic changes can predict fluid responsiveness during one-lung ventilation: an observational study

Background

To evaluate the ability of tidal volume challenge (VTC)-induced hemodynamic changes to predict fluid responsiveness in patients during one-lung ventilation (OLV).

Methods

80 patients scheduled for elective thoracoscopic surgery with OLV were enrolled. The inclusion criteria were: age ≥ 18 years, American Society of Anesthesiologists physical status I-III, normal right ventricular function, normal left ventricular systolic function (ejection fraction ≥55%), and normal or slightly impaired diastolic function. The study protocol was implemented 15 min after starting OLV. Simultaneous recordings were performed for hemodynamic variables of diameter of left ventricular outflow tract, velocity time integral (VTI) of aortic valve, and stroke volume (SV), and ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC were calculated at four time points: with VT 5 mL/kg (T1); after VT increased from 5 mL/kg to 8 mL/kg and maintained at this level for 2 min (T2); after VT was adjusted back to 5 mL/kg for 2 min (T3); and after volume expansion (250 mL of 0.9% saline infused over 10-15 min) (T4). Patients were considered as responders to fluid administration if SV increased by ≥10%. Receiver operating characteristic (ROC) curves for percent decrease in SV, VTI, and MAP by VTC were generated to evaluate their ability to discriminate fluid responders from nonresponders.

Results

Of the 58 patients analyzed, there were 32 responders (55%) and 26 nonresponders (45%). The basic characteristics were comparable between the two groups (p > 0.05). The area under the curve (AUC) for ΔSV-VTC, ΔVTI-VTC, and ΔMAP-VTC to discriminate responders from nonresponders were 0.81 (95% CI: 0.68-0.90), 0.79 (95% CI: 0.66-0.89), and 0.56 (95% CI: 0.42-0.69). The best threshold for ΔSV-VTC was -16.1% (sensitivity, 78.1%; specificity, 84.6%); the best threshold for ΔVTI-VTC was -14.5% (sensitivity, 78.1%; specificity, 80.8%).

Conclusion

Tidal volume challenge-induced relative change of stroke volume and velocity time integral can predict fluid responsiveness in patients during one-lung ventilation.Clinical Trial Registration: Chinese Clinical Trial Registry, No: chictr210051310.

Temporal and Spatial Patterns of Inflammation and Tissue Injury in Patients with Postoperative Respiratory Failure after Lung Resection Surgery: A Nested Case-Control Study

Thoracic surgeries involving resection of lung tissue pose a risk of severe postoperative pulmonary complications, including acute respiratory distress syndrome (ARDS) and respiratory failure. Lung resections require one-lung ventilation (OLV) and, thus, are at higher risk of ventilator-induced lung injury (VILI) attributable to barotrauma and volutrauma in the one ventilated lung, as well as hypoxemia and reperfusion injury on the operated lung. Further, we also aimed to assess the differences in localized and systemic markers of tissue injury/inflammation in those who developed respiratory failure after lung surgery versus matched controls who did not develop respiratory failure. We aimed to assess the different inflammatory/injury marker patterns induced in the operated and ventilated lung and how this compared to the systemic circulating inflammatory/injury marker pattern. A case-control study nested within a prospective cohort study was performed. Patients with postoperative respiratory failure after lung surgery (n = 5) were matched with control patients (n = 6) who did not develop postoperative respiratory failure. Biospecimens (arterial plasma, bronchoalveolar lavage separately from ventilated and operated lungs) were obtained from patients undergoing lung surgery at two timepoints: (1) just prior to initiation of OLV and (2) after lung resection was completed and OLV stopped. Multiplex electrochemiluminescent immunoassays were performed for these biospecimen. We quantified 50 protein biomarkers of inflammation and tissue injury and identified significant differences between those who did and did not develop postoperative respiratory failure. The three biospecimen types also display unique biomarker patterns.

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.

A randomised controlled trial on roles of prostaglandin E1 nebulization among patients undergoing one lung ventilation

Background

Prostaglandin E1 (PGE1) has been reported to maintain adequate oxygenation among patients under 60% FiO₂ one-lung ventilation (OLV). This research aimed to explore whether PGE1 is safe in pulmonary shunt and oxygenation under 40% FiO₂ OLV and provide a reference concentration of PGE1.

Methods

Totally 90 esophageal cancer patients treated with thoracotomy were enrolled in this study, randomly divided into three groups (n = 30/group): Group A (60% FiO₂ and 0.1 µg/kg PGE1), Group B (40% FiO₂ and 0.1 µg/kg PGE1), and Group C (40% FiO₂, 0.2 µg/kg PGE1). Primary outcomes were oxygenation and pulmonary shunt during OLV. Secondary outcomes included oxidative stress after OLV.

Results

During OLV, patients in Group C and B had lower levels of PaO₂, SaO₂, SpO₂, MAP, and Qs/Qt than those in Group A (P < 0.05). At T2 (OLV 10 min), patients in Group C and B exhibited a lower level of PaO₂/FiO₂ than those in Group A, without any statistical difference at other time points. The IL-6 levels of patients in different groups were different at T8 (F = 3.431, P = 0.038), with IL-6 in Group C being lower than that in Group B and A. MDA levels among the three groups differed at T5 (F = 4.692, P = 0.012) and T7 (F = 5.906, P = 0.004), with the MDA level of Group C being lower than that of Group B and A at T5, and the MDA level of Group C and B being lower than that of Group A at T7. In terms of TNF-α level, patients in Group C had a lower level than those in Group B and A at T8 (F = 3.598, P = 0.033). Compared with patients who did not use PGE1, patients in Group C had comparable complications and lung infection scores.

Conclusion

The concentration of FiO₂ could be reduced from 60 to 40% to maintain oxygenation. 40% FiO₂ + 0.2 µg/kg PGE1 is recommended as a better combination on account of its effects on the inflammatory factors.

Trial registration: Chictr.org.cn identifier: ChiCTR1800018288, 09/09/2018.

Enhanced recovery after surgery: anesthesia-related components

Background: Enhanced recovery after surgery (ERAS) is a multidisciplinary and multimodal evidence-based approach aimed at improving the recovery of surgical patients. Successful implementation of ERAS protocols requires proper perioperative communication and collaboration among surgeons, anesthesiologists, nurses, and other medical personnel.Current Concepts: The anesthesiologist is the clinical leader responsible for the ERAS program. Preoperative patient evaluation, optimization, and patient education are essential components of the ERAS program. The program also involves preoperative fasting and carbohydrate loading to minimize catabolic effects. Selection of an appropriate anesthetic regimen, fluid and temperature management, avoidance of intra/postoperative nausea and vomiting, and multimodal pain management are the key components of ERAS for which the anesthesiologist is responsible.Discussion and Conclusion: Factors that enable the successful implementation of ERAS include the willingness to change to ERAS, formation of multidisciplinary teams to improve cooperation, and support from the hospital management, as well as standardization of order sets and care processes and the appropriate use of audits. As the leader of the ERAS team, the anesthesiologist should be actively involved in comprehensive management of the patient during the perioperative period.

Current Practice Issues in Thoracic Anesthesia

This review discusses the present strategies in lung separation, the various types of double-lumen tubes (DLTs), and the use of bronchial blockers (BBs). Methods of selecting the correct DLT size and the role of videolaryngoscopy in placing a DLT are reviewed. Mechanisms whereby inhaled anesthetics may be protective during one-lung ventilation (OLV) are highlighted. The risk and prevention of fire during thoracic procedures are discussed.

Cognitive Aids for the Management of Thoracic Anesthesia Emergencies: Consensus Guidelines on Behalf of a Canadian Thoracic Taskforce

A cognitive aid is a tool used to help people accurately and efficiently perform actions. Similarly themed cognitive aids may be collated into a manual to provide relevant information for a specific context (eg, operating room emergencies). Expert content and design are paramount to facilitate the utility of a cognitive aid, especially during a crisis when accessible memory may be limited and distractions may impair task completion. A cognitive aid does not represent a rigid approach to problem-solving or a replacement for decision-making. Successful cognitive aid implementation requires dedicated training, access, and culture integration. Here the authors present a set of evidence-based cognitive aids for thoracic anesthesia emergencies developed by a Canadian thoracic taskforce.

Effects of inverse ratio ventilation combined with lung protective ventilation on pulmonary function in patients with severe burns for surgery

Objective

To investigate the effects of inverse ratio ventilation combined with lung-protective ventilation on pulmonary function and inflammatory factors in severe burn patients undergoing surgery. Populations and Methods: Eighty patients with severe burns undergoing elective surgery were divided randomly into two groups: control (CG, n = 40) and experiment (EG, n = 40). The CG had conventional ventilation, whereas the EG were ventilated with tidal volume (TV) of 6–8 ml/kg, I (inspiration): E (expiration) of 2:1, and positive end-expiratory pressure (PEEP) 5 cm H2O. The following variables were evaluated before (T0), 1 h after start of surgery (T1) and after surgery (T2): oxygenation index (OI), partial pressure of carbon dioxide (PaCO₂), TV, peak airway pressure (Ppeak), mean airway pressure (Pmean), PEEP, pulmonary dynamic compliance (Cdyn), alveolar–arterial difference of oxygen partial pressure D(A-a)O₂, lactic acid (Lac), interleukin (IL)-6 and IL-10, and lung complications. Results: At T1 and T2 time points, the OI, Pmean and Cdyn were significantly greater in the EG than in the CG while the TV, Ppeak, D(A-a)O₂, IL-6 and IL-10 were significantly smaller in the EG than in the CG. At the end of the surgery, the Lac was significantly smaller in the EG than in the CG (1.28 ± 0.19 vs. 1.40 ± 0.23 mmol/L). Twenty-four hours after the surgery, significantly more patients had hypoxemia (27.5 vs. 10.0%), increased expectoration (45.0 vs. 22.5%), increased lung texture or exudation (37.5 vs. 17.5%) in the CG than in the EG. Conclusions: Inverse ratio ventilation combined with lung-protective ventilation can reduce Ppeak, increase Pmean and Cdyn, improve the pulmonary oxygenation function, and decrease ILs in severe burn surgery patients.

A Lower Tidal Volume Regimen during One-lung Ventilation for Lung Resection Surgery Is Not Associated with Reduced Postoperative Pulmonary Complications

BACKGROUND

Protective ventilation may improve outcomes after major surgery. However, in the context of one-lung ventilation, such a strategy is incompletely defined. The authors hypothesized that a putative one-lung protective ventilation regimen would be independently associated with decreased odds of pulmonary complications after thoracic surgery.

METHODS

The authors merged Society of Thoracic Surgeons Database and Multicenter Perioperative Outcomes Group intraoperative data for lung resection procedures using one-lung ventilation across five institutions from 2012 to 2016. They defined one-lung protective ventilation as the combination of both median tidal volume 5 ml/kg or lower predicted body weight and positive end-expiratory pressure 5 cm H2O or greater. The primary outcome was a composite of 30-day major postoperative pulmonary complications.

RESULTS

A total of 3,232 cases were available for analysis. Tidal volumes decreased modestly during the study period (6.7 to 6.0 ml/kg; P < 0.001), and positive end-expiratory pressure increased from 4 to 5 cm H2O (P < 0.001). Despite increasing adoption of a "protective ventilation" strategy (5.7% in 2012 vs. 17.9% in 2016), the prevalence of pulmonary complications did not change significantly (11.4 to 15.7%; P = 0.147). In a propensity score matched cohort (381 matched pairs), protective ventilation (mean tidal volume 6.4 vs. 4.4 ml/kg) was not associated with a reduction in pulmonary complications (adjusted odds ratio, 0.86; 95% CI, 0.56 to 1.32). In an unmatched cohort, the authors were unable to define a specific alternative combination of positive end-expiratory pressure and tidal volume that was associated with decreased risk of pulmonary complications.

CONCLUSIONS

In this multicenter retrospective observational analysis of patients undergoing one-lung ventilation during thoracic surgery, the authors did not detect an independent association between a low tidal volume lung-protective ventilation regimen and a composite of postoperative pulmonary complications.

EDITOR’S PERSPECTIVE

Efficacy of height-based formula to predict insertion depth of left-sided double lumen tube: A prospective observational study

The insertion depth of the left-sided double-lumen tube needs careful positioning and bronchoscopic confirmation. Several formulae based on body height have been used for estimating the optimal insertion depth of a left-sided double-lumen tube. We conducted this prospective study to test the hypothesis that our earlier developed height-based formula (0.25 × body height^0.916) could predict the accurate insertion depth of a left-sided double-lumen tube. After obtaining ethical approval, 66 patients who underwent thoracic surgery were included. A left-sided double-lumen tube was advanced blindly to the predicted depth of insertion calculated using our formula. The optimal position of the left-sided double-lumen tube was confirmed using a fibreoptic bronchoscope. The primary outcome was the percentage of tubes placed in the optimal position without the need for further adjustments. The secondary outcomes included the need for bronchoscopic adjustments and the final correct insertion depth of the left-sided double-lumen tube. The formula resulted in an optimum position of the left-sided double-lumen tube without further adjustments in 45 patients (70%) (95% confidence interval 58%-80%). The left-sided double-lumen tube was withdrawn or advanced in 18.2% and 12.1%, respectively, to achieve the optimal insertion depth. We found that our formula provided satisfactory positioning in about 70% of patients and that in the remaining patients, the adjustments required to achieve satisfactory positioning under fibreoptic bronchoscope guidance were minimal. Nevertheless, as it is not possible to predict which patients will have a satisfactory tube position, bronchoscopic confirmation for the final positioning is still required.

Effects of prostaglandin E1 nebulization of ventilated lung under 60%O2 one lung ventilation on patients' oxygenation and oxidative stress: a randomised controlled trial

Background

High FiO₂ during one-lung ventilation (OLV) can improve oxygenation, but increase the risk of atelectasis and oxidative stress. The aim of this study was to analyze whether Prostaglandin E₁ (PGE₁) can improve oxygenation and attenuate oxidative stress during OLV under a lower FiO₂.

Method

Ninety patients selectively undergoing thoracotomy for esophageal cancer were randomly divided into three groups (n = 30/group): Group P (FiO₂ = 0.6, inhaling PGE₁ 0.1 μg/kg), Group L (FiO₂ = 0.6) and Group C (FiO₂ = 1.0). The primary outcomes were oxygenation and pulmonary shunt during OLV. Secondary outcomes included haemodynamics, respiratory mechanics and oxidative stress in serum.

Results

Patients in Group P had significantly higher PaO₂ and lower shunt fraction in 30 min of OLV compared with Group L. Compared with Group C, patients in Group P had similar levels of PaO₂/FiO₂ in 60 min and higher levels of PaO₂/FiO₂ at 2 h during OLV. The levels of PvO₂ and SvO₂ in Group P and Group L were significantly lower than Group C. Patients in Group P and Group L had significantly higher levels of superoxide dismutase and lower levels of malondialdehyde than Group C. No significant differences were found in SPO₂, ETCO₂, PaCO₂, Paw, HR and MAP among the three groups. The complications in Group C were significantly higher than another two groups.

Conclusion

PGE₁ can maintain adequate oxygenation in patients with low FiO₂ (0.6) during OLV. Reducing FiO₂ to 0.6 during OLV can decrease the levels of oxidative stress and complications after OLV.

Trial registration

chictr.org.cn identifier: ChiCTR1800017100.

The Year in Thoracic Anesthesia: Selected Highlights from 2019

THIS special article is the 4th in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan; the associate editor-in-chief, Dr. Augoustides; and the editorial board for the opportunity to expand this series, the research highlights of the year that specifically pertain to the specialty of thoracic anesthesia. The major themes selected for 2019 are outlined in this introduction, and each highlight is reviewed in detail in the main body of the article. The literature highlights in this specialty for 2019 include updates in the preoperative assessment and optimization of patients undergoing lung resection and esophagectomy, updates in one lung ventilation (OLV) and protective ventilation during OLV, a review of recent meta-analyses comparing truncal blocks with paravertebral catheters and the introduction of a new truncal block, meta-analyses comparing nonintubated video-assisted thoracoscopic surgery (VATS) with those performed using endotracheal intubation, a review of the Society of Thoracic Surgeons (STS) recent composite score rating for pulmonary resection of lung cancer, and an update of the Enhanced Recovery After Surgery (ERAS) guidelines for both lung and esophageal surgery.

Volume of tidal gas movement in the nonventilated lung during one-lung ventilation and its relevant factors

Background

The passive ventilation of nonventilated lung results in tidal gas movement (TGM) and thus affects lung collapse. The present study aimed to measure the volume of TGM and to analyse the relevant factors of the TGM index (TGM/body surface area).

Methods

One hundred eight patients scheduled for elective thoracoscopic surgeries were enrolled. Lung isolation was achieved with a double-lumen endobronchial tube (DLT). The paediatric spirometry sensor was connected to the double-lumen connector of the nonventilated lung to measure the volume of TGM during one-lung ventilation (OLV) in the lateral position. The TGM index was calculated. The multiple linear regression was analysed using the TGM index as the dependent variables. Independent variables were also recorded: 1) age, sex, body mass index (BMI); 2) forced vital capacity (FVC), FEV₁/FVC, minute ventilation volume (MVV); 3) dynamic lung compliance (Cdyn) and peak inspiratory pressure (PIP) during dual lung ventilation; 4) the side of OLV; and 5) whether lung puncture for localization of the pulmonary nodule was performed on the day of surgery. The oxygen concentration in the nonventilated lung was measured at 5 min after OLV, and its correlation with the TGM index was analysed.

Results

The volume of TGM in the nonventilated lung during OLV was 78 [37] mL. The TGM index was 45 [20] mL/m² and was negatively correlated with the oxygen concentration in the nonventilated lung at 5 min after OLV. The multiple linear regression model for the TGM index was deduced as follows: TGM index (mL/m²) = C + 12.770 × a − 3.987 × b-1.237 × c-2.664 × d, where C is a constant 95.621 mL/m², a is 1 for males and 0 for females, b is 1 for right OLV and 0 for left OLV, c is BMI (kg/m²), and d is PIP (cmH₂O).

Conclusions

The TGM index is negatively correlated with the oxygen concentration of the nonventilated lung at 5 min after OLV. Sex, side of OLV, BMI and PIP are independently correlated with the TGM index.

Trial registration

This study was registered at ChiCTR (www.chictr.org.cn, ChiCTR1900024220) on July 1, 2019.

Anesthetic considerations for lung resection: preoperative assessment, intraoperative challenges and postoperative analgesia

This article is intended to provide a general overview of the anesthetic management for lung resection surgery including the preoperative evaluation of the patient, factors influencing the intraoperative anesthetic management and options for postoperative analgesia. Lung cancer is the leading cause of death among cancer patients in the United States. In patients undergoing lung resection, perioperative pulmonary complications are the major etiology of morbidity and mortality. Risk stratification of patients should be part of the preoperative assessment to predict their risk of short-term vs. long-term pulmonary complications. Improvements in surgical technique and equipment have made video assisted thoracoscopy and robotically assisted thoracoscopy the procedures of choice for thoracic surgeries. General anesthesia including lung isolation has become essential for optimizing visualization of the operative lung but may itself contribute to pulmonary complications. Protective lung ventilation strategies may not prevent acute lung injury from one-lung ventilation, but it may decrease the amount of overall lung injury by using small tidal volumes, positive end expiratory pressure, low peak and plateau airway pressures and low inspired oxygen fraction, as well as by keeping surgical time as short as possible. Because of the high incidence of chronic post-thoracotomy pain syndrome following thoracic surgery, which can impact a patient's normal daily activities for months to years after surgery, postoperative analgesia is a necessary part of the anesthetic plan. Multiple options such as thoracic epidural analgesia, intravenous narcotics and several nerve blocks can be considered in order to prevent or attenuate chronic pain syndromes. Enhanced recovery after thoracic surgery is a relatively new topic with many elements taken from the experience with colorectal surgery. The goal of enhanced recovery is to improve patient outcome by improving organ function and decreasing postoperative complications, and therefore decreasing length of hospital stay.

Anesthesia and enhanced recovery in subxiphoid video-assisted thoracoscopic surgery

Subxiphoid video-assisted thoracoscopic surgery (VATS) is a surgical approach in minimally invasive thoracic surgery that aims to aid enhanced recovery by reducing postoperative pain by avoiding instrumentation of the intercostal spaces. Access through a subxiphoid port presents challenges for both the surgeon and anaesthetist. Particularly for left sided procedures, the heart can be compressed resulting in arrhythmia and haemodynamic compromise. The anaesthetic team play an important role in ensuring the success of subxiphoid VATS procedures. The key is continuous and comprehensive monitoring for circulatory disturbance and arrhythmia intraoperatively. Should arrhythmia develop it is important that it is managed rapidly and effectively in such a manner to minimize haemodynamic disturbance. In this article, important considerations for anaesthesia in subxiphoid VATS procedures is presented and solutions presented.

Management of 1-Lung Ventilation-Variation and Trends in Clinical Practice: A Report From the Multicenter Perioperative Outcomes Group

BACKGROUND

Lung-protective ventilation (LPV) has been demonstrated to improve clinical outcomes in surgical patients. There are very limited data on the current use of LPV for patients undergoing 1-lung ventilation (1LV) despite evidence that 1LV may be a particularly important setting for its use. In this multicenter study, we report trends in ventilation practice for patients undergoing 1LV.

METHODS

The Multicenter Perioperative Outcomes Group database was used to identify patients undergoing 1LV. We retrieved and calculated median initial and overall tidal volume (VT) for the cohort and for high-risk subgroups (female sex, obesity [body mass index >30 kg/m], and short stature), percentage of patients receiving positive end-expiratory pressure (PEEP) ≥5 cm H2O, LPV during 1LV (VT ≤ 6 mL/kg predicted body weight [PBW] and PEEP ≥5 cm H2O), and ventilator driving pressure (ΔP; plateau airway pressure - PEEP).

RESULTS

Data from 5609 patients across 4 institutions were included in the analysis. Median VT was calculated for each case and since the data were normally distributed, the mean is reported for the entire cohort and subgroups. Mean of median VT during 1LV for the cohort was 6.49 ± 1.82 mL/kg PBW. VT (mL/kg PBW) for high-risk subgroups was significantly higher; 6.86 ± 1.97 for body mass index ≥30 kg/m, 7.05 ± 1.92 for female patients, and 7.33 ± 2.01 for short stature patients. Mean of the median VT declined significantly over the study period (from 6.88 to 5.72; P < .001), and the proportion of patients receiving LPV increased significantly over the study period (from 9.1% to 54.6%; P < .001). These changes coincided with a significant decrease in ΔP during the study period, from 19.4 cm H2O during period 1 to 17.3 cm H2O in period 12 (P = .003).

CONCLUSIONS

Despite a growing awareness of the importance of protective ventilation, a large proportion of patients undergoing 1LV continue to receive VT PEEP levels outside of recommended thresholds. Moreover, VT remains higher and LPV less common in high-risk subgroups, potentially placing them at elevated risk for iatrogenic lung injury.

Effect of lung protective ventilation on coronary heart disease patients undergoing lung cancer resection

Background

Mechanical ventilation, especially large tidal volume (Vt) one-lung ventilation (OLV), can cause ventilator-induced lung injury (VILI) that can stimulate cytokines. Meanwhile, cytokines are considered very important factor influencing coronary heart disease (CHD) patient prognosis. So minimization of pulmonary inflammatory responses by reduction of cytokine levels for CHD undergoing lung resection during OLV should be a priority. Because previous studies have demonstrated that lung-protective ventilation (LPV) reduced lung inflammation, this ventilation approach was studied for CHD patients undergoing lung resection here to evaluate the effects of LPV on pulmonary inflammatory responses.

Methods

This is a single center, randomized controlled trial. Primary endpoint of the study are plasma concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, IL-10 and C-reactive protein (CRP). Secondary endpoints include respiratory variables and hemodynamic variables. 60 CHD patients undergoing video-assisted thoracoscopic lung resection were randomly divided into conventional ventilation group [10 mL/kg Vt and 0 cmH₂O positive end-expiratory pressure (PEEP), C group] and protective ventilation group (6 mL/kg Vt and 6 cmH₂O PEEP, P group; 30 patients/group). Hemodynamic variables, peak inspiratory pressure (Ppeak), dynamic compliance (Cdyn), arterial oxygen tension (PaO₂) and arterial carbon dioxide tension (PaCO₂) were recorded as test data at three time points: T1-endotracheal intubation for two-lung ventilation (TLV) when breathing and hemodynamics were stable; T2-after TLV was substituted with OLV when breathing and hemodynamics were stable; T3-OLV was substituted with TLV at the end of surgery when breathing and hemodynamics were stable. The concentrations of TNF-α, IL-6, IL-10 and CRP in patients' blood in both groups at the very beginning of OLV (beginning of OLV) and the end moment of the surgery (end of surgery) were measured.

Results

The P group exhibited greater PaO₂, higher Cdyn and lower Ppeak than the C group at T2, T3 (P<0.05). At the end moment of the surgery, although the P group tended to exhibit higher TNF-α and IL-10 values than the C group, the differences did not reach statistical significance(P=0.0817, P=0.0635). Compared with C group at the end moment of the surgery, IL-6 and CRP were lower in P group, the differences were statistically significant (P=0.0093, P=0.0005). There were no significant differences in hemodynamic variables between the two groups (P>0.05).

Conclusions

LPV can effectively reduce the airway pressure, improve Cdyn and PaO₂, reduce concentrations of IL-6 and CRP during lung resection of CHD patients.Trial registration: The trial was registered in the Chinese Clinical Trial Registry.

Can Dexmedetomidine Improve Arterial Oxygenation and Intrapulmonary Shunt during One-lung Ventilation in Adults Undergoing Thoracic Surgery? A Meta-analysis of Randomized, Placebo-controlled Trials

Background:

One-lung ventilation (OLV) is a common ventilation technology during thoracic surgery that can cause serious clinical problems. We aimed to conduct a meta-analysis to compare oxygenation and intrapulmonary shunt during OLV in adults undergoing thoracic surgery with dexmedetomidine (Dex) versus placebo to assess the influence and safety of using Dex.

Methods:

Randomized controlled trials comparing lung protection in patients who underwent thoracic surgery with Dex or a placebo were retrieved from PubMed, EMBASE, MEDLINE, Cochrane Library, and China CNKI database. The following information was extracted from the paper: arterial oxygen partial pressure (PaO₂), PaO₂/inspired oxygen concentration (PaO₂/FiO₂, oxygenation index [OI]), intrapulmonary shunt (calculated as Qs/Qt), mean arterial pressure (MAP), heart rate (HR), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, superoxide dismutase (SOD), and malondialdehyde (MDA).

Results:

Fourteen randomized controlled trials were included containing a total of 625 patients. Compared with placebo group, Dex significantly increased PaO₂/FiO₂ (standard mean difference [SMD] = 0.98, 95% confidence interval [CI] [0.72, 1.23], P < 0.00001). Besides, Qs/Qt (SMD= −1.22, 95% CI [−2.20, −0.23], P = 0.020), HR (SMD= −0.69, 95% CI [−1.20, 0.17], P = 0.009), MAP (SMD= −0.44, 95% CI [−0.84, 0.04], P = 0.030), the concentrations of TNF-α (SMD = −1.55, 95% CI [−2.16, −0.95], P <0.001), and IL-6 (SMD = −1.53, 95% CI [−2.37, −0.70], P = 0.0003) were decreased in the treated group, when compared to placebo group. No significant difference was found in MDA (SMD = −1.14, 95% CI [−3.48, 1.20], P = 0.340) and SOD (SMD = 0.41, 95% CI [−0.29, 1.10], P = 0.250) between the Dex group and the placebo group. Funnel plots did not detect any significant publication bias.

Conclusions:

Dex may improve OI and reduce intrapulmonary shunt during OLV in adults undergoing thoracic surgery. However, this conclusion might be weakened by the limited number of pooled studies and patients.

Phenylephrine does not improve oxygenation during one-lung ventilation: A randomized, double-blind, cross-over study

Background

Phenylephrine is an α₁ adrenergic receptor agonist that causes pulmonary vasoconstriction, and so may effectively enhance hypoxic pulmonary vasoconstriction (HPV). However, there is little evidence that phenylephrine augments HPV in clinical situations. This study aimed to evaluate the clinical effects of phenylephrine infusion on oxygenation during one-lung ventilation (OLV) in patients undergoing thoracic surgery.

Methods

This was a prospective, randomized, double-blind, cross-over study. Included patients were those undergoing elective thoracic surgery in the lateral decubitus position with OLV. Patients were randomly allocated to two groups. The N-P group initially had OLV with normal saline infusion for 30 minutes; after a 10 minute interval, OLV was then maintained with phenylephrine infusion for 30 minutes. The P-N group had the drug-infusion in the reverse order. The primary outcome was arterial partial pressure of oxygen. Secondary outcomes were mean arterial pressure, heart rate, pulse pressure variation, perfusion index, and difference between bladder and skin temperature. Statistical analysis was performed using the student t-test, Fisher's exact test, and ANOVA for Cross-over design. P < 0.05 was considered statistically significant.

Results

Twenty-nine patients were analyzed. Although phenylephrine infusion significantly increased mean arterial pressure (P < 0.001), arterial partial pressure of oxygen did not differ between the two timepoints (P = 0.19). There was no carryover effect in arterial partial pressure of oxygen (P = 0.14). Phenylephrine infusion significantly decreased heart rate (P = 0.02) and pulse pressure variation (P < 0.001).

Conclusions

Phenylephrine infusion did not improve oxygenation during OLV. The present results indicate that phenylephrine does not have clinically meaningful effects on HPV.

Trial registration

University Hospital Medical Information Network 000024317

Bronchial suction does not facilitate lung collapse when using a double-lumen tube during video-assisted thoracoscopic surgery: a randomized controlled trial

Background

Bronchial suction through the lumen of a bronchial blocker has been reported to accelerate lung collapse. The aim of the current study was to examine whether bronchial suction could also facilitate lung collapse when using a double-lumen tube (DLT).

Methods

Eighty patients scheduled for elective video-assisted thoracoscopic surgery for lung cancer using a DLT for one-lung ventilation (OLV) were randomised into an arm that received bronchial suction and an arm that underwent spontaneous collapse (n=40 per arm). For bronchial suction, a pressure of -30 cmH₂O was applied to the lumen of the non-ventilated lung during the first minute of OLV. The primary endpoint was the degree of lung collapse at 10 min after the start of OLV, assessed on a 10-point visual analogue scale (0: fully inflated; 10: complete collapse). Secondary outcomes included lung collapse at 1 and 5 min after the start of OLV, as well as occurrence of intraoperative hypoxemia.

Results

Median (interquartile range) lung collapse scores at 10 min were statistically greater in the bronchial suction arm than in the spontaneous collapse arm [9.0 (9.0-9.0) vs. 8.5 (8.0-9.0); P=0.004]. Lung collapse was also statistically greater in the bronchial suction arm at 5 min [8.0 (7.0-8.0) vs. 7.0 (6.25-7.0) min; P=0.002] and 1 min [4.0 (4.0-5.0) vs. 2.0 (2.0-2.0) min; P<0.001]. None of the patients experienced intraoperative hypoxemia and operative complications.

Conclusions

Bronchial suction resulted in statistically greater but not clinically meaningful lung collapse when using a DLT. However, greater degree of lung collapse at 1-min could be helpful in reducing accidental injuries.

Anesthetic Considerations for Mediastinal Staging Procedures for Lung Cancer

Tumor staging is critical for the treatment of lung malignancies. Invasive techniques of lung tumor staging can be accomplished via mediastinoscopy, endobronchial ultrasound, and video-assisted thoracoscopy. Anesthesiologists taking care of patients undergoing mediastinal staging procedures might face different challenges. In this narrative review, the authors summarize the literature on the anesthetic considerations for mediastinal staging procedures.

Anesthesia for Lung Transplantation

Perioperative management of patients undergoing lung transplantation is challenging and requires constant communication among the surgical, anesthesia, perfusion, and nursing teams. Although all aspects of anesthetic management are important, certain intraoperative strategies (mechanical ventilation, fluid management, extracorporeal mechanical support deployment) have tremendous impact on the subsequent evolution of the lung transplant recipient, especially with respect to allograft function, and should be carefully considered. This review highlights some of the intraoperative anesthetic challenges and opportunities during lung transplantation.

Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery

BACKGROUND

The use of lung-protective ventilation (LPV) strategies may minimize iatrogenic lung injury in surgical patients. However, the identification of an ideal LPV strategy, particularly during one-lung ventilation (OLV), remains elusive. This study examines the role of ventilator management during OLV and its impact on clinical outcomes.

METHODS

Data were retrospectively collected from the hospital electronic medical record and the Society of Thoracic Surgery database for subjects undergoing thoracic surgery with OLV between 2012 and 2014. Mean tidal volume (VT) during two-lung ventilation and OLV and ventilator driving pressure (ΔP) (plateau pressure - positive end-expiratory pressure [PEEP]) were analyzed for the 1,019 cases that met the inclusion criteria. Associations between ventilator parameters and clinical outcomes were examined by multivariate linear regression.

RESULTS

After the initiation of OLV, 73.3, 43.3, 18.8, and 7.2% of patients received VT greater than 5, 6, 7, and 8 ml/kg predicted body weight, respectively. One hundred and eighty-four primary and 288 secondary outcome events were recorded. In multivariate logistic regression modeling, VT was inversely related to the incidence of respiratory complications (odds ratio, 0.837; 95% CI, 0.729 to 0.958), while ΔP predicted the development of major morbidity when modeled with VT (odds ratio, 1.034; 95% CI, 1.001 to 1.068).

CONCLUSIONS

Low VT per se (i.e., in the absence of sufficient PEEP) has not been unambiguously demonstrated to be beneficial. The authors found that a large proportion of patients continue to receive high VT during OLV and that VT was inversely related to the incidence of respiratory complications and major postoperative morbidity. While low (physiologically appropriate) VT is an important component of an LPV strategy for surgical patients during OLV, current evidence suggests that, without adequate PEEP, low VT does not prevent postoperative respiratory complications. Thus, use of physiologic VT may represent a necessary, but not independently sufficient, component of LPV.

[Anesthesia in thoracic surgery]

Thoracic surgery represents a special challenge for anesthesia and requires a high level of human and material resources. Accurate knowledge of the pathophysiology is essential for selection of the anesthetic procedure, the separation of the lungs, monitoring and treatment of hemodynamics as well as for postoperative follow-up care. The increasing number of thoracic interventions and patients who are often suffering from complex diseases require close interdisciplinary cooperation between surgeons, anesthesiologists and intensive care specialists. In addition to the anesthetic techniques particular attention must be paid to the prevention of perioperative complications that can have a relevant effect on patient outcome. In particular hypoxemia during one-lung ventilation influences postoperative morbidity and mortality. Protective pulmonary ventilation strategies play an important role in prevention of postoperative acute lung injury.

Noninvasive Measurement of Carbon Dioxide during One-Lung Ventilation with Low Tidal Volume for Two Hours: End-Tidal versus Transcutaneous Techniques

BACKGROUND

There may be significant difference between measurement of end-tidal carbon dioxide partial pressure (PetCO2) and arterial carbon dioxide partial pressure (PaCO2) during one-lung ventilation with low tidal volume for thoracic surgeries. Transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring can be used continuously to evaluate PaCO2 in a noninvasive fashion. In this study, we compared the accuracy between PetCO2 and PtcCO2 in predicting PaCO2 during prolonged one-lung ventilation with low tidal volume for thoracic surgeries.

METHODS

Eighteen adult patients who underwent thoracic surgeries with one-lung ventilation longer than two hours were included in this study. Their PetCO2, PtcCO2, and PaCO2 values were collected at five time points before and during one-lung ventilation. Agreement among measures was evaluated by Bland-Altman analysis.

RESULTS

Ninety sample sets were obtained. The bias and precision when PtcCO2 and PaCO2 were compared were 4.1 ± 6.5 mmHg during two-lung ventilation and 2.9 ± 6.1 mmHg during one-lung ventilation. Those when PetCO2 and PaCO2 were compared were -11.8 ± 6.4 mmHg during two-lung ventilation and -11.8 ± 4.9 mmHg during one-lung ventilation. The differences between PtcCO2 and PaCO2 were significantly lower than those between PetCO2 and PaCO2 at all five time-points (p < 0.05).

CONCLUSIONS

PtcCO2 monitoring was more accurate for predicting PaCO2 levels during prolonged one-lung ventilation with low tidal volume for patients undergoing thoracic surgeries.

Sevoflurane suppresses hypoxia-induced growth and metastasis of lung cancer cells via inhibiting hypoxia-inducible factor-1α

PURPOSE

Hypoxia promotes the progression of lung cancer cells. Unfortunately, anesthetic technique might aggravate hypoxia of lung cancer cells. Sevoflurane is a commonly used anesthetic. Its effect on hypoxia-induced aggressiveness of lung cancer cells remains unknown. The aim of the study is to investigate the effects of sevoflurane on hypoxia-induced growth and metastasis of lung cancer cells. As hypoxia-inducible factor-1α (HIF-1α) plays a pivotal role in mediating the adaptation and tolerance of cancer cells under hypoxic microenvironment, the role of HIF-1α in the effect of sevoflurane on hypoxia-induced growth and metastasis has also been elucidated.

METHODS

A549 cells were treated with normoxia, hypoxia, co-treatment of sevoflurane and hypoxia, and dimethyloxaloylglycine (DMOG, a HIF-1α agonist) for 4 h, respectively. MTT assay and colony formation assay were used to evaluate cell growth. Transwell assay was performed to detect invasion and migration ability. The protein level of HIF-1α, X-linked inhibitor of apoptosis protein (XIAP), survivin, fascin, heparanase (HPA), and p38 MAPK were determined by Western blotting.

RESULTS

Hypoxia enhanced proliferation and metastatic potential of cells. Sevoflurane could suppress hypoxia-induced growth and metastasis ability of cells. Furthermore, HIF-1α, XIAP, survivin, fascin and HPA were down-regulated significantly by the co-treatment of sevoflurane and hypoxia as compared to hypoxia treatment. DMOG abolished the inhibiting effects of sevoflurane on hypoxia-induced growth and metastasis ability of cells. In addition, sevoflurane partly reversed the increase of p38 MAPK activity that was induced by hypoxia.

CONCLUSIONS

Sevoflurane could suppress hypoxia-induced growth and metastasis of lung cancer cells, which might be associated with modulating HIF-1α and its down-stream genes. Moreover, p38 MAPK signaling pathway was involved in the regulation of HIF-1α by sevoflurane.