Hypoxia During One-Lung Ventilation-A Review and Update

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

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

One-lung ventilation with fixed and variable tidal volumes on oxygenation and pulmonary outcomes: A randomized trial

OBJECTIVE

Test the hypothesis that one-lung ventilation with variable tidal volume improves intraoperative oxygenation and reduces postoperative pulmonary complications after lung resection.

BACKGROUND

Constant tidal volume and respiratory rate ventilation can lead to atelectasis. Animal and human ARDS studies indicate that oxygenation improves with variable tidal volumes. Since one-lung ventilation shares characteristics with ARDS, we tested the hypothesis that one-lung ventilation with variable tidal volume improves intraoperative oxygenation and reduces postoperative pulmonary complications after lung resection.

DESIGN

Randomized trial.

SETTING

Operating rooms and a post-anesthesia care unit.

PATIENTS

Adults having elective open or video-assisted thoracoscopic lung resection surgery with general anesthesia were randomly assigned to intraoperative ventilation with fixed (n = 70) or with variable (n = 70) tidal volumes.

INTERVENTIONS

Patients assigned to fixed ventilation had a tidal volume of 6 ml/kgPBW, whereas those assigned to variable ventilation had tidal volumes ranging from 6 ml/kg PBW ± 33% which varied randomly at 5-min intervals.

MEASUREMENTS

The primary outcome was intraoperative oxygenation; secondary outcomes were postoperative pulmonary complications, mortality within 90 days of surgery, heart rate, and SpO2/FiO2 ratio.

RESULTS

Data from 128 patients were analyzed with 65 assigned to fixed-tidal volume ventilation and 63 to variable-tidal volume ventilation. The time-weighted average PaO2 during one-lung ventilation was 176 (86) mmHg in patients ventilated with fixed-tidal volume and 147 (72) mmHg in the patients ventilated with variable-tidal volume, a difference that was statistically significant (p < 0.01) but less than our pre-defined clinically meaningful threshold of 50 mmHg. At least one composite complication occurred in 11 (17%) of patients ventilated with variable-tidal volume and in 17 (26%) of patients assigned to fixed-tidal volume ventilation, with a relative risk of 0.67 (95% CI 0.34-1.31, p = 0.24). Atelectasis in the ventilated lung was less common with variable-tidal volumes (4.7%) than fixed-tidal volumes (20%) in the initial three postoperative days, with a relative risk of 0.24 (95% CI 0.01-0.8, p = 0.02), but there were no significant late postoperative differences. No other secondary outcomes were both statistically significant and clinically meaningful.

CONCLUSION

One-lung ventilation with variable tidal volume does not meaningfully improve intraoperative oxygenation, and does not reduce postoperative pulmonary complications.

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

BACKGROUND

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

METHODS

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

DISCUSSION

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

TRIAL REGISTRATION

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

Ultrasound-guided versus conventional lung recruitment manoeuvres in thoracic surgery: a randomised controlled study

Lung recruitment manoeuvres (RMs) during mechanical ventilation may reduce atelectasis, however, the optimal recruitment strategy for patients undergoing thoracic surgery remains unknown. Our study was designed to investigate whether ultrasound-guided lung RMs is superior to conventional RMs in reducing perioperative atelectasis during thoracic surgery with one-lung ventilation. We conducted a randomised controlled clinical trial from August 2022 to September 2022. Sixty patients scheduled for video-assisted thoracoscopic surgery (VATS) under general anaesthesia were enrolled. Subjects were randomly divided into the ultrasound-guided RMs group (manual inflation guided by lung ultrasound) or conventional RMs group (manual inflation with 30 cmH2O pressure). Lung ultrasound were performed at three predefined time points (1 min after anaesthetic induction; after RMs at the end of surgery; before discharge from postanesthesia care unit [PACU]). The primary outcome was lung ultrasound score before discharge from the PACU after extubation. In the early postoperative period, lung aeration deteriorated in both groups even after lung RMs. However, ultrasound-guided lung RMs had significantly lower lung ultrasound scores when compared with conventional RMs in bilateral lungs (2.0 [0.8-4.0] vs. 8.0 [3.8-10.3], P < 0.01) at the end of surgery, which remained before patients discharged from the PACU. Accordingly, the lower incidence of atelectasis was found in ultrasound-guided RMs group than in conventional RMs group (7% vs. 53%; P < 0.01) at the end of surgery. Ultrasound-guided RMs is superior to conventional RMs in improving lung aeration and reducing the incidence of lung atelectasis at early postoperative period in patients undergoing VATS. The study protocol was approved by the Institutional Review Board of the Fudan University Shanghai Cancer Center (No. 220,825,810; date of approval: August 5, 2022) and registered on Chinese Clinical Trial Registry (registration number: ChiCTR2200062761).

Comprehensive characterization of small noncoding RNA profiles in hypoxia-induced pulmonary hypertension (HPH) rat tissues

Hypoxia-induced pulmonary hypertension (HPH) is a fatal cardiovascular disease characterized by an elevation in pulmonary artery pressure, resulting in right ventricular dysfunction and eventual heart failure. Exploring the pathogenesis of HPH is crucial, and small noncoding RNAs (sncRNAs) are gaining recognition as potential regulators of cellular responses to hypoxia. In this study, we conducted a comprehensive analysis of sncRNA profiles in eight tissues of male HPH rats using high-throughput sequencing. Our study unveiled several sncRNAs, with the brain, kidney, and spleen exhibiting the highest abundance of microRNA (miRNA), tRNA-derived small RNA (tDR), and small nucleolar RNA (snoRNA), respectively. Moreover, we identified numerous tissue-specific and hypoxia-responsive sncRNAs, particularly miRNAs and tDRs. Interestingly, we observed arm switching in miRNAs under hypoxic conditions and a significant increase in the abundance of 5' tRNA-halves among the total tDRs during hypoxia. Overall, our study provides a comprehensive characterization of the sncRNA profiles in HPH rats.

Effects of nonintubated thoracoscopic surgery on postoperative neurocognitive function: a randomized controlled trial

OBJECTIVES

Postoperative neurocognitive disorder following thoracoscopic surgery with general anaesthesia may be linked to reduced intraoperative cerebral oxygenation and perioperative inflammation, which can potentially be exacerbated by mechanical ventilation. However, nonintubated thoracoscopic surgery, which utilizes regional anaesthesia and maintains spontaneous breathing, provides a unique model for studying the potential benefits of avoiding mechanical ventilation. This approach allows investigation into the impact on perioperative neurocognitive profiles, inflammatory responses and intraoperative cerebral oxygen levels.

METHODS

In total, 110 patients undergoing thoracoscopic surgery were randomly equally assigned to the intubated group and the nonintubated group. Regional cerebral oxygenation was monitored during surgery. Serum neuroinflammatory biomarkers, including interleukin-6 and glial fibrillary acidic protein, were measured at baseline (before surgery) and 24 h after surgery. Postoperative complication severity was compared using the Comprehensive Complication Index. The primary outcome was perioperative changes in neurocognitive test score, which was assessed at baseline, 24 h and 6 months after surgery.

RESULTS

Patients in the nonintubated group had higher neurocognitive test scores at 24 h (69.9 ± 10.5 vs 65.3 ± 11.8; P = 0.03) and 6 months (70.6 ± 6.7 vs 65.4 ± 8.1; P < 0.01) after surgery and significantly higher regional cerebral oxygenation over time during one-lung ventilation (P = 0.03). Patients in the intubated group revealed a significantly higher postoperative serum interleukin-6 level (group by time interaction, P = 0.04) and a trend towards a significantly higher serum glial fibrillary acidic protein level (group by time interaction, P = 0.11). Furthermore, patients in the nonintubated group had a significantly lower Comprehensive Complication Index (9.0 ± 8.2 vs 6.1 ± 7.1; P < 0.05).

CONCLUSIONS

Nonintubated thoracoscopic surgery was associated with improved postoperative neurocognitive recovery, more stable intraoperative cerebral oxygenation, ameliorated perioperative inflammation and attenuated postoperative complication severity.

Hypoxemia in School-age Children Undergoing One-lung Ventilation: A Retrospective Cohort Study from the Multicenter Perioperative Outcomes Group

BACKGROUND

Risk factors for hypoxemia in school-age children undergoing one-lung ventilation remain poorly understood. The hypothesis was that certain modifiable and nonmodifiable factors may be associated with increased risk of hypoxemia in school-age children undergoing one-lung ventilation and thoracic surgery.

METHODS

The Multicenter Perioperative Outcomes Group database was queried for children 4 to 17 yr of age undergoing one-lung ventilation. Patients undergoing vascular or cardiac procedures were excluded. The original cohort was divided into two cohorts: 4 to 9 and 10 to 17 yr of age inclusive. All records were reviewed electronically for the primary outcome of hypoxemia during one-lung ventilation, which was defined as an oxygen saturation measured by pulse oximetry (Spo2) less than 90% for 3 min or longer continuously, while severe hypoxemia was defined as Spo2 less than 90% for 5 min or longer. Potential modifiable and nonmodifiable risk factors associated with these outcomes were evaluated using separate multivariable least absolute shrinkage and selection operator regression analyses for each cohort. The covariates evaluated included age, extremes of weight, American Society of Anesthesiologists Physical Status of III or higher, duration of one-lung ventilation, preoperative Spo2 less than 98%, approach to one-lung ventilation, right operative side, video-assisted thoracoscopic surgery, lower tidal volume ventilation (defined as tidal volume of 6 ml/kg or less and positive end-expiratory pressure of 4 cm H2O or greater for more than 80% of the duration of one-lung ventilation), and procedure type.

RESULTS

The prevalence of hypoxemia in the 4- to 9-yr-old cohort and the 10- to 17-yr-old cohort was 24 of 228 (10.5% [95% CI, 6.5 to 14.5%]) and 76 of 1,012 (7.5% [95% CI, 5.9 to 9.1%]), respectively. The prevalence of severe hypoxemia in both cohorts was 14 of 228 (6.1% [95% CI, 3.0 to 9.3%]) and 47 of 1,012 (4.6% [95% CI, 3.3 to 5.8%]). Initial Spo2 less than 98% was associated with hypoxemia in the 4- to 9-yr-old cohort (odds ratio, 4.20 [95% CI, 1.61 to 6.29]). Initial Spo2 less than 98% (odds ratio, 2.76 [95% CI, 1.69 to 4.48]), extremes of weight (odds ratio, 2.18 [95% CI, 1.29 to 3.61]), and right-sided cases (odds ratio, 2.33 [95% CI, 1.41 to 3.92]) were associated with an increased risk of hypoxemia in the older cohort. Increasing age (1-yr increment; odds ratio, 0.88 [95% CI, 0.80 to 0.97]) was associated with a decreased risk of hypoxemia.

CONCLUSIONS

An initial room air oxygen saturation of less than 98% was associated with an increased risk of hypoxemia in all children 4 to 17 yr of age. Extremes of weight, right-sided cases, and decreasing age were associated with an increased risk of hypoxemia in children 10 to 17 yr of age.

EDITOR’S PERSPECTIVE

Lung ultrasound for evaluating perioperative atelectasis and aeration in the post-anesthesia care unit

PURPOSE

Lung ultrasound is widely accepted as a reliable, noninvasive tool for evaluating lung status at the bedside. We assessed the impact of perioperative variables on atelectasis and lung aeration using lung ultrasound, and their correlation with postoperative oxygenation in patients undergoing general anesthesia.

METHODS

This prospective observational study evaluated 93 consecutive patients scheduled to undergo elective non-cardiothoracic surgery under general anesthesia. Lung ultrasound was performed 5 min after admission to the post-anesthesia care unit (PACU). Twelve pulmonary quadrants were selected for each ultrasound examination. The lung ultrasound scores and atelectasis status were calculated. The oxygenation assessment was obtained by arterial blood gas analysis before discharge from the PACU.

RESULTS

Thirty-two patients (34%) had atelectasis in at least one of the 12 evaluated segments, whereas 12 patients (13%) had atelectasis in at least three segments. The proportion of B-lines (≥ 3) and atelectasis in the inferolateral and posterior regions was significantly higher than in other regions. Patients with lung ultrasound scores ≥ 5 had a higher body mass index and lower PaO2 before discharge from the PACU than those with scores < 5. Patients with atelectasis had higher body mass indices and lung ultrasound scores. The presence of ≥ 2 regions of atelectasis was associated with lower PaO2. Using multivariate analysis, body mass index, intraoperative body position, and sex independently correlated with lung ultrasound scores. Age and lung ultrasound scores independently correlated with hypoxemia.

CONCLUSION

Lung ultrasound enables early postoperative evaluation of atelectasis and lung aeration, which are closely associated with postoperative oxygenation.

National Trends, Risk Factors, and Outcomes of Acute In-Hospital Stroke Following Lung Transplantation in the United States: Analysis of the United Network for Organ Sharing Registry

BACKGROUND

Lung transplantation (LTx) is the definitive treatment for end-stage lung failure. However, there have been no large, long-term studies on the impact of acute in-hospital stroke in this population.

RESEARCH QUESTION

What are the trends, risk factors, and outcomes of acute stroke in patients undergoing LTx in the United States?

STUDY DESIGN AND METHODS

We identified adult first-time isolated LTx recipients from the United Network for Organ Sharing database, which comprehensively captures every transplant in the United States, between May 2005 and December 2020. Stroke was defined as occurring at any time after LTx but prior to discharge. Multivariable logistic regression with stepwise feature elimination was used to identify risk factors for stroke. Freedom from death in patients with a stroke vs those without a stroke was evaluated with Kaplan-Meier analysis. Cox proportional hazards analysis was used to identify predictors of death at 24 months.

RESULTS

Of 28,564 patients (median age, 60 years; 60% male), 653 (2.3%) experienced an acute in-hospital stroke after LTx. Median follow-up was 1.2 (stroke) and 3.0 (non-stroke) years. Annual incidence of stroke increased (1.5% in 2005 to 2.4% in 2020; P for trend = .007), as did lung allocation score and utilization of post-LTx extracorporeal membrane oxygenation (P = .01 and P < .001, respectively). Compared with those without stroke, patients with stroke had lower survival at 1 month (84% vs 98%), 12 months (61% vs 88%), and 24 months (52% vs 80%) (log-rank test, P < .001 for all). In Cox analysis, acute stroke conferred a high hazard of mortality (hazard ratio, 3.01; 95% CI, 2.67-3.41). Post-LTx extracorporeal membrane oxygenation was the strongest risk factor for stroke (adjusted OR, 2.98; 95% CI, 2.19-4.06).

INTERPRETATION

Acute in-hospital stroke post-LTx has been increasing over time and is associated with markedly worse short- and long-term survival. As increasingly sicker patients undergo LTx as well as experience stroke, further research on stroke characteristics, prevention, and management strategies is warranted.

Effect of permissive hypercarbia on lung oxygenation during one-lung ventilation and postoperative pulmonary complications in patients undergoing thoracic surgery: A prospective randomised controlled trial

BACKGROUND

The effect of hypercarbia on lung oxygenation during thoracic surgery remains unclear.

OBJECTIVE

To investigate the effect of hypercarbia on lung oxygenation during one-lung ventilation in patients undergoing thoracic surgery and evaluate the incidence of postoperative pulmonary complications.

DESIGN

Prospective randomised controlled trial.

SETTING

A tertiary university hospital in the Republic of Korea from November 2019 to December 2020.

PATIENTS

Two hundred and ninety-seven patients with American Society of Anaesthesiologists physical status II to III, scheduled to undergo elective lung resection surgery.

INTERVENTION

Patients were randomly assigned to Group 40, 50, or 60. An autoflow ventilation mode with a lung protective ventilation strategy was applied to all patients. Respiratory rate was adjusted to maintain a partial pressure of arterial carbon dioxide of 40 ± 5 mmHg in Group 40, 50 ± 5 mmHg in Group 50 and 60 ± 5 mmHg in Group 60 during one-lung ventilation and at the end of surgery.

MAIN OUTCOME MEASURES

The primary outcome was the arterial oxygen partial pressure/fractional inspired oxygen ratio after 60 min of one-lung ventilation.

RESULTS

Data from 262 patients were analysed. The partial pressure/fractional inspired oxygen ratio was significantly higher in Group 50 and Group 60 than in Group 40 (269.4 vs. 262.9 vs. 214.4; P  < 0.001) but was not significantly different between Group 50 and Group 60. The incidence of postoperative pulmonary complications was comparable among the three groups.

CONCLUSION

Permissive hypercarbia improved lung oxygenation during one-lung ventilation without increasing the risk of postoperative pulmonary complications or the length of hospital stay.

TRIAL REGISTRATION

NCT04175379.

An Unusual Cause of End-Tidal Carbon Dioxide Rise During One-Lung Ventilation

A relatively common problem that may arise during one-lung ventilation is elevation of end-tidal carbon dioxide (ETCO2), which has several potential etiologies. This case report describes a 69-year-old woman with carcinoid tumor undergoing a robotic left lower lobectomy complicated by an acute rise in ETCO2 during one-lung ventilation, without an immediately identifiable cause. Thorough evaluation revealed CO2 leak through an open bronchial lumen resulting in an artificially high ETCO2 reading. This case report demonstrates the importance of performing a comprehensive assessment during acute changes in ETCO2 while also considering changes in the surgical field, which may contribute to these findings.

Right-Sided Minimally Invasive Direct Coronary Artery Bypass: Clinical Experience and Perspectives

Objective: Minimally invasive direct coronary artery bypass grafting (MIDCAB) using the left internal thoracic artery to the left descending artery is a clinical routine in the treatment of coronary artery disease. Far less is known on right-sided MIDCAB (r-MIDCAB) using the right internal thoracic artery (RITA) to the right coronary artery (RCA). We aimed to present our experience in patients with complex coronary artery disease who underwent r-MIDCAB. Materials and Methods: Between October 2019 and January 2023, 11 patients received r-MIDCAB using RITA to RCA bypass in a minimally invasive technique via right anterior minithoracotomy without using a cardiopulmonary bypass. Underlying coronary disease was complex right coronary artery stenosis (n = 7) and anomalous right coronary artery (ARCA; n = 4). All procedure-related and outcome data were evaluated prospectively. Results: Successful minimally invasive revascularization was achieved in all patients (n = 11). There were no conversions to sternotomy and no re-explorations for bleeding. Furthermore, no myocardial infarction, no strokes, and, most importantly, no deaths were observed. During the follow-up period (median 24 months), all patients were alive and 90% were completely angina free. Two patients received a repeated revascularization after surgery but independently from the RITA-RCA bypass, which was fully competent in both patients. Conclusion: Right-sided MIDCAB can be performed safely and effectively in patients with expected technically challenging percutaneous coronary intervention of the RCA and in patients with ARCA. Mid-term results showed high freedom from angina in nearly all patients. Further studies with larger patient cohorts and more evidence are needed to provide the best revascularization strategy for patients suffering from isolated complex RCA stenosis and ARCA.

Effect of Deferasirox on Shunt Fraction During Thoracic Surgery With One-Lung Ventilation: A Randomized Controlled Study

Context Deferasirox, an iron chelator, can potentially reduce intraoperative right-to-left shunt and improve oxygenation in patients undergoing thoracic surgery requiring one-lung ventilation (OLV) by potentiating hypoxic pulmonary vasoconstriction (HPV). Aim The aim was to determine the effect of deferasirox on the intraoperative shunt fraction (SF) of patients undergoing thoracic surgery using OLV. Study design and settings This was a prospective, single-blind, randomized, controlled study. The study was conducted at a tertiary-care hospital. Methods Before surgery, 64 patients were allocated to two groups comprising 32 patients each. Group D patients were administered deferasirox, while those in group C were given a placebo. We included patients with the American Society of Anesthesiologists physical status III or IV, aged 18-60 years, undergoing elective thoracic surgery needing OLV. SF was the primary outcome variable. Secondary outcome variables were arterial oxygen tension (PaO₂), peripheral oxygen saturation (SpO₂), the ratio of PaO₂ and inspired oxygen concentration (P/F), and complications such as desaturation episodes, hypotension, and tachycardia. Results Baseline and postoperative values of outcome variables were statistically similar in both groups. Intraoperative values of SF were lower and PaO₂, SpO₂, and P/F were higher in group D. The incidence of intraoperative desaturation was lower in group D. Conclusion We conclude that pre-treatment with deferasirox reduces intraoperative SF and improves oxygenation during thoracic surgery using OLV.

The anesthesia management of totally thoracoscopic cardiac surgery: A single-center retrospective study

Anesthesia management of Totally thoracoscopic cardiac surgery (TTCS) has been the subject of much debate and discussion. In this single center retrospective study, we summarize the experience of clinical anesthesia management for TTCS by review the medical records of our medical center and look forward to its future development. In this retrospective study, 103 patients (49 male and 54 female) were enrolled, the mean age was 56.7 ± 14.4 years old. The participants underwent Mitral Valve Replacement (MVR) + Tricuspid Valve Annuloplasty (TVA) (42, 40.8%), Mitral Valve Annuloplasty (MVA) + TVA (38, 36.9%), MVA (21, 20.4%), and MVR (2, 1.9%)，respectively. Intraoperative hypoxemia, radiographic pulmonary infiltrates, and pneumonia were observed in 19 (18.4%), 84 (81.6%), and 13 (12.6%) patients, respectively. The LOS of ICU and POD were as follows: MVR + TVA (55.1 ± 25h, 9.9 ± 3.5 d), MVA + TVA (56.5 ± 28.4h, 9.4 ± 4.2d), MVA (37.9 ± 21.9h, 8.1 ± 2.3d) and MVR (48 ± 4.2h, 7.5 ± 2.1d). No reintubation, reoperations, postoperative cognitive dysfunction, 30-day mortality were observed in the present study. The present study demonstrated that applying this anesthesia management for TTCS associated with acceptable morbidity, intensive care unit and postoperative hospital lengths of stay. The finding from the present study might provide some new approach for Anesthesia management of TTCS.

One-Lung Ventilation during Rigid Bronchoscopy Using a Single-Lumen Endotracheal Tube: A Descriptive, Retrospective Single-Center Study

Using one-lung ventilation (OLV) through a single-lumen endotracheal tube (SLT) in the untreated lung during rigid bronchoscopy (RB) and jet ventilation, high oxygenation can be guaranteed, whilst procedures requiring thermal energy in the other lung are still able to be used. This pilot study aimed to examine the bronchoscopy-associated risks and feasibility of OLV using an SLT during RB in patients with malignant airway stenosis. All consecutive adult patients with endobronchial malignant lesions receiving OLV during RB from 1 January 2017 to 12 May 2021 were included. We assessed perioperative complications in 25 RBs requiring OLV. Bleeding grades 1, 2, and 3 complicated the procedure in two (8%), five (20%), and five (20%) patients, respectively. The median saturation of peripheral oxygen remained at 94% (p = 0.09), whilst the median oxygen supply did not increase significantly from 0 L/min to 2 L/min (p = 0.10) within three days after the bronchoscopy. The 30-day survival rate of the patients was 79.1% (95% CI 58.4-91.1%), all of whom reported an improvement in subjective well-being after the bronchoscopy. OLV using an SLT during RB could be a new treatment approach for endobronchial ablative procedures without increasing bronchoscopy-associated risks, allowing concurrent high-energy treatments.

Scope actuation system for articulated laparoscopes

BACKGROUND

An articulated laparoscope comprises a rigid shaft with an articulated distal end to change the viewing direction. The articulation provides improved navigation of the operating field in confined spaces. Furthermore, incorporation of an actuation system tends to enhance the control of an articulated laparoscope.

METHODS

A preliminary prototype of a scope actuation system to maneuver an off-the-shelf articulated laparoscope (EndoCAMaleon by Karl Storz, Germany) was developed. A user study was conducted to evaluate this prototype for the surgical paradigm of video-assisted thoracic surgery. In the study, the subjects maneuvered an articulated scope under two modes of operation: (a) actuated mode where an operating surgeon maneuvers the scope using the developed prototype and (b) manual mode where a surgical assistant directly maneuvers the scope. The actuated mode was further assessed for multiple configurations based on the orientation of the articulated scope at the incision.

RESULTS

The data show the actuated mode scored better than the manual mode on all the measured performance parameters including (a) total duration to visualize a marked region, (a) duration for which scope focus shifts outside a predefined visualization region, and (c) number of times for which scope focus shifts outside a predefined visualization region. Among the different configurations tested using the actuated mode, no significant difference was observed.

CONCLUSIONS

The proposed articulated scope actuation system facilitates better navigation of an operative field as compared to a human assistant. Secondly, irrespective of the orientation in which an articulated scope's shaft is inserted through an incision, the proposed actuation system can navigate and visualize the operative field.

Muscular tissue desaturation and pneumonia in patients receiving lung cancer surgery: a cohort study

BACKGROUND

Post-operative pneumonia (POP) is a common complication of lung cancer surgery, and muscular tissue oxygenation is a root cause of post-operative complications. However, the association between muscular tissue desaturation and POP in patients receiving lung cancer surgery has not been specifically studied. This study aimed to investigate the potential use of intra-operative muscular tissue desaturation as a predictor of POP in patients undergoing lung cancer surgery.

METHODS

This cohort study enrolled patients (≥55 years) who had undergone lobectomy with one-lung ventilation. Muscular tissue oxygen saturation (SmtO 2 ) was monitored in the forearm (over the brachioradialis muscle) and upper thigh (over the quadriceps) using a tissue oximeter. The minimum SmtO 2 was the lowest intra-operative measurement at any time point. Muscular tissue desaturation was defined as a minimum baseline SmtO 2 of <80% for >15 s. The area under or above the threshold was the product of the magnitude and time of desaturation. The primary outcome was the association between intra-operative muscular tissue desaturation and POP within seven post-operative days using multivariable logistic regression. The secondary outcome was the correlation between SmtO 2 in the forearm and that in the thigh.

RESULTS

We enrolled 174 patients. The overall incidence of muscular desaturation (defined as SmtO 2 < 80% in the forearm at baseline) was approximately 47.1% (82/174). The patients with muscular desaturation had a higher incidence of pneumonia than those without desaturation (28.0% [23/82] vs. 12.0% [11/92]; P  = 0.008). The multivariable analysis revealed that muscular desaturation was associated with an increased risk of pneumonia (odds ratio: 2.995, 95% confidence interval: 1.080-8.310, P  = 0.035) after adjusting for age, American Society of Anesthesiologists status, Assess Respiratory Risk in Surgical Patients in Catalonia score, smoking, use of peripheral nerve block, propofol, and study center.

CONCLUSION

Muscular tissue desaturation, defined as a baseline SmtO 2 < 80% in the forearm, may be associated with an increased risk of POP.

TRIAL REGISTRATION

No. ChiCTR-ROC-17012627.

Hypoxemia in thoracoscopic lung resection surgery using a video double-lumen tube versus a conventional double-lumen tube: A propensity score-matched analysis

Background

Malposition of the double-lumen tubes (DLTs) may lead to hypoxemia during one-lung ventilation (OLV). Video double-lumen tubes (VDLTs) enable continuous observation of DLT position and avoid displacement. We aimed to investigate whether VDLTs could reduce the incidence of hypoxemia during OLV compared with conventional double-lumen tubes (cDLT) in thoracoscopic lung resection surgery.

Methods

This was a retrospective cohort study. Adult patients who underwent elective thoracoscopic lung resection surgery and required VDLTs or cDLTs for OLV at Shanghai Chest Hospital from January 2019 to May 2021 were included. The primary outcome was the incidence of hypoxemia during OLV between VDLT and cDLT. Secondary outcomes included bronchoscopy use, the degree of PaO₂ decline, and arterial blood gas indices.

Results

A total of 1,780 patients were finally analyzed in propensity score-matched cohorts (VDLT vs. cDLT 1:1 n = 890). The incidence of hypoxemia decreased from 6.5% (58/890) in cDLT group to 3.6% (32/890) in VDLT group (Relative Risk [RR]: 1.812, 95% CI: 1.19-2.76, p = 0.005). The use of bronchoscopy was reduced by 90% in VDLT group (VDLT 10.0% (89/890) vs. cDLT 100% (890/890), p < 0.001). PaO₂ after OLV was 221 [136.0-325.0] mmHg in cDLT group compared to 234 [159.7-336.2] mmHg in VDLT group, p = 0.003. The percentage of PaO₂ decline was 41.4 [15.4-61.9] % in cDLT group, while it was 37.7 [8.7-55.9] % in the VDLT group, p < 0.001. In patients who suffered from hypoxemia, there were no significant differences in arterial blood gas indices or the percentage of PaO₂ decline.

Conclusion

VDLTs reduce the incidence of hypoxemia and the use of bronchoscopy during OLV compared with cDLTs. VDLT may be a feasible option for thoracoscopic surgery.

Individualised flow-controlled ventilation versus pressure-controlled ventilation in a porcine model of thoracic surgery requiring one-lung ventilation: A laboratory study

BACKGROUND

Flow-controlled ventilation (FCV) enables precise determination of dynamic compliance due to a continuous flow coupled with direct tracheal pressure measurement. Thus, pressure settings can be adjusted accordingly in an individualised approach.

OBJECTIVE

The aim of this study was to compare gas exchange of individualised FCV to pressure-controlled ventilation (PCV) in a porcine model of simulated thoracic surgery requiring one-lung ventilation (OLV).

DESIGN

Controlled interventional trial conducted on 16 domestic pigs.

SETTING

Animal operating facility at the Medical University of Innsbruck.

INTERVENTIONS

Thoracic surgery was simulated with left-sided thoracotomy and subsequent collapse of the lung over a period of three hours. When using FCV, ventilation was performed with compliance-guided pressure settings. When using PCV, end-expiratory pressure was adapted to achieve best compliance with peak pressure adjusted to achieve a tidal volume of 6 ml kg -1 during OLV.

MAIN OUTCOME MEASURES

Gas exchange was assessed by the Horowitz index (= P aO 2 /FIO 2 ) and CO 2 removal by the P aCO 2 value in relation to required respiratory minute volume.

RESULTS

In the FCV group ( n  = 8) normocapnia could be maintained throughout the OLV trial despite a significantly lower respiratory minute volume compared to the PCV group ( n  = 8) (8.0 vs. 11.6, 95% confidence interval, CI -4.5 to -2.7 l min -1 ; P  < 0.001), whereas permissive hypercapnia had to be accepted in PCV ( P aCO 2 5.68 vs. 6.89, 95% CI -1.7 to -0.7 kPa; P  < 0.001). The Horowitz index was comparable in both groups but calculated mechanical power was significantly lower in FCV (7.5 vs. 22.0, 95% CI -17.2 to -11.8 J min -1 ; P  < 0.001).

CONCLUSIONS

In this porcine study FCV maintained normocapnia during OLV, whereas permissive hypercapnia had to be accepted in PCV despite a substantially higher minute volume. Reducing exposure of the lungs to mechanical power applied by the ventilator in FCV offers a possible advantage for this mode of ventilation in terms of lung protection.

Effects of Positive End-Expiratory Pressure on Intraocular Pressure during One-Lung Ventilation in the Lateral Decubitus Position-A Prospective Randomized Trial

Background and Objectives: The effect of positive end-expiratory pressure (PEEP) on intraocular pressure (IOP) is debatable. There have been no studies investigating the effects of PEEP on IOP during one-lung ventilation (OLV). We aimed to investigate the effects of PEEP on IOP in patients undergoing OLV for video-assisted thoracoscopic surgery (VATs). Materials and Methods: Fifty-two patients undergoing VATs were divided into a zero-PEEP (ZEEP) and a 6 cmH₂O of PEEP (PEEP) groups. IOP, ocular perfusion pressure (OPP), and respiratory and hemodynamic parameters were measured before induction (T1), immediately following endotracheal intubation (T2), 30 min (T3) and 60 min (T4) after a position change to the lateral decubitus position (LDP) and OLV, and 10 min following two-lung ventilation near the end of the surgery (T5). Results: There was no significant difference in IOP and OPP between the two groups. The IOP of the dependent eye was significantly higher than that of the non-dependent eye during LDP in both groups. Peak inspiratory pressure was significantly higher in the PEEP group than in the ZEEP group at T3-T5. Dynamic compliance was significantly higher in the PEEP group than in the ZEEP group at T2-T5. The ratio of arterial oxygen partial pressure to fractional inspired oxygen was significantly higher in the PEEP group than in the ZEEP group at T4. Conclusions: Applying 6 cmH₂O of PEEP did not increase IOP but enhanced dynamic compliance and oxygenation during OLV. These results suggest that 6 cmH₂O of PEEP can be safely applied during OLV in LDP.

Effects of Iloprost on Arterial Oxygenation and Lung Mechanics during One-Lung Ventilation in Supine-Positioned Patients: A Randomized Controlled Study

Patients undergoing one-lung ventilation (OLV) in the supine position face an increased risk of intraoperative hypoxia compared with those in the lateral decubitus position. We hypothesized that iloprost (ILO) inhalation improves arterial oxygenation and lung mechanics. Sixty-four patients were enrolled and allocated to either the ILO or control group (n = 32 each), to whom ILO or normal saline was administered. The partial pressure of the arterial oxygen/fraction of inspired oxygen (PaO₂/FiO₂) ratio, dynamic compliance, alveolar dead space, and hemodynamic variables were assessed 20 min after anesthesia induction with both lungs ventilated (T1) and 20 min after drug nebulization in OLV (T2). A linear mixed model adjusted for group and time was used to analyze repeated variables. While the alveolar dead space remained unchanged in the ILO group, it increased at T2 in the control group (n = 30 each) (p = 0.002). No significant differences were observed in the heart rate, mean blood pressure, PaO₂/FiO₂ ratio, or dynamic compliance in either group. Selective ILO nebulization was inadequate to enhance oxygenation parameters during OLV in the supine position. However, it favorably affected alveolar ventilation during OLV in supine-positioned patients without adverse hemodynamic effects.

Spectral Entropy Monitoring Accelerates the Emergence from Sevoflurane Anesthesia in Thoracic Surgery: A Randomized Controlled Trial

The clinical efficacy of spectral entropy monitoring in improving postoperative recovery remains unclear. This trial aimed to investigate the impact of M-Entropy (GE Healthcare, Helsinki, Finland) guidance on emergence from anesthesia and postoperative delirium in thoracic surgery. Adult patients undergoing video-assisted thoracoscopic surgery for lung resection at a medical center were randomly allocated into the M-Entropy guidance group (n = 39) and the control group (n = 37). In the M-Entropy guidance group, sevoflurane anesthesia was titrated to maintain response and state entropy values between 40 and 60 intraoperatively. In the control group, the dosing of sevoflurane was adjusted based on clinical judgment and vital signs. The primary outcome was time to spontaneous eye opening. M-Entropy guidance significantly reduced the time proportion of deep anesthesia (entropy value <40) during surgery, mean difference: −21.5% (95% confidence interval (CI): −32.7 to −10.3) for response entropy and −24.2% (−36.3 to −12.2) for state entropy. M-Entropy guidance significantly shortened time to spontaneous eye opening compared to clinical signs, mean difference: −154 s (95% CI: −259 to −49). In addition, patients of the M-Entropy group had a lower rate of emergence agitation (absolute risk reduction: 0.166, 95% CI: 0.005−0.328) and delirium (0.245, 0.093−0.396) at the postanesthesia care unit. M-Entropy-guided anesthesia hastened awakening and potentially prevented emergence agitation and delirium after thoracic surgery. These results may provide an implication for facilitating postoperative recovery and reducing the complications associated with delayed emergence and delirium.

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.

Flurbiprofen used in one-lung ventilation improves intraoperative regional cerebral oxygen saturation and reduces the incidence of postoperative delirium

BACKGROUND

We previously demonstrated that flurbiprofen increased arterial oxygen partial pressure and reduced intrapulmonary shunts. The present study aims to investigate whether flurbiprofen improves intraoperative regional cerebral oxygen saturation (rScO₂) and reduces the incidence of postoperative delirium (POD) in elderly patients undergoing one-lung ventilation (OLV).

METHODS

One hundred and twenty patients undergoing thoracoscopic lobectomy were randomly assigned to the flurbiprofen-treated group (n = 60) and the control-treated group (n = 60). Flurbiprofen was intravenously administered 20 minutes before skin incision. The rScO₂ and partial pressure of arterial oxygen (PaO₂) were recorded during the surgery, and POD was measured by the Confusion Assessment Method (CAM) within 5 days after surgery. The study was registered in the Chinese Clinical Trial Registry with the number ChiCTR1800020032.

RESULTS

Compared with the control group, treatment with flurbiprofen significantly improved the mean value of intraoperative rScO₂ as well as the PaO₂ value (P < 0.05, both) and significantly reduced the baseline values of the rScO₂ area under threshold (AUT) (P < 0.01) at 15, 30, and 60 min after OLV in the flurbiprofen-treated group. After surgery, the POD incidence in the flurbiprofen-treated group was significantly decreased compared with that in the control group (P < 0.05).

CONCLUSION

Treatment with flurbiprofen may improve rScO₂ and reduce the incidence of POD in elderly patients undergoing thoracoscopic one-lung ventilation surgery for lung cancer.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org/cn/, identifier ChiCTR1800020032.

Peri-operative approach to esophagectomy: a narrative review from the anesthesiological standpoint

Objective

This review summarizes the peri-operative anesthesiological approaches to esophagectomy considering the best up-to-date, evidence-based medicine, discussed from the anesthesiologist’s standpoint.

Background

Esophagectomy is the only curative therapy for esophageal cancer. Despite the many advancements made in the surgical treatment of this tumour, esophagectomy still carries a morbidity rate reaching 60%. Patients undergoing esophagectomy should be referred to high volume centres where they can receive a multidisciplinary approach to treatment, associated with better outcomes. The anesthesiologist is the key figure who should guide the peri-operative phase, from diagnosis through to post-surgery rehabilitation. We performed an updated narrative review devoted to the study of anesthesia management for esophagectomy in cancer patients.

Methods

We searched MEDLINE, Scopus and Google Scholar databases from inception to May 2021. We used the following terms: “esophagectomy”, “esophagectomy AND pre-operative evaluation”, “esophagectomy AND protective lung ventilation”, “esophagectomy AND hemodynamic monitoring” and “esophagectomy AND analgesia”. We considered only articles with abstract written in English and available to the reader. We excluded single case-reports.

Conclusions

Pre-operative anesthesiological evaluation is mandatory in order to stratify and optimize any medical condition. During surgery, protective ventilation and judicious fluid management are the cornerstones of intraoperative “protective anesthesia”. Post-operative care should be provided by an intensive care unit or high-dependency unit depending on the patient’s condition, the type of surgery endured and the availability of local resources. The provision of adequate post-operative analgesia favours early mobilization and rapid recovery. Anesthesiologist has an important role during the peri-operative care for esophagectomy. However, there are still some topics that need to be further studied to improve the outcome of these patients.

The hypoxic pulmonary vasoconstriction: From physiology to clinical application in thoracic surgery

More than 70 years after its original report, the hypoxic pulmonary vasoconstriction (HPV) response continues to spark scientific interest on its mechanisms and clinical implications, particularly for anesthesiologists involved in thoracic surgery. Selective airway intubation and one-lung ventilation (OLV) facilitates the surgical intervention on a collapsed lung while the HPV redirects blood flow from the "upper" non-ventilated hypoxic lung to the "dependent" ventilated lung. Therefore, by limiting intrapulmonary shunting and optimizing ventilation-to-perfusion (V/Q) ratio, the fall in arterial oxygen pressure (PaO₂) is attenuated during OLV. The HPV involves a biphasic response mobilizing calcium within pulmonary vascular smooth muscles, which is activated within seconds after exposure to low alveolar oxygen pressure and that gradually disappears upon re-oxygenation. Many factors including acid-base balance, the degree of lung expansion, circulatory volemia as well as lung diseases and patient age affect HPV. Anesthetic agents, analgesics and cardiovascular medications may also interfer with HPV during the perioperative period. Since HPV represents the homeostatic mechanism for regional ventilation-to-perfusion matching and in turn, for optimal pulmonary oxygen uptake, a clear understanding of HPV is clinically relevant for all anesthesiologists.

Anesthesia for thoracic surgery in infants and children

The management of infants and children presenting for thoracic surgery poses a variety of challenges for anesthesiologists. A thorough understanding of the implications of developmental changes in cardiopulmonary anatomy and physiology, associated comorbid conditions, and the proposed surgical intervention is essential in order to provide safe and effective clinical care. This narrative review discusses the perioperative anesthetic management of pediatric patients undergoing noncardiac thoracic surgery, beginning with the preoperative assessment. The considerations for the implementation and management of one-lung ventilation (OLV) will be reviewed, and as will the anesthetic implications of different surgical procedures including bronchoscopy, mediastinoscopy, thoracotomy, and thoracoscopy. We will also discuss pediatric-specific disease processes presenting in neonates, infants, and children, with an emphasis on those with unique impact on anesthetic management.

Hypoxemia in Young Children Undergoing One-lung Ventilation: A Retrospective Cohort Study

BACKGROUND

One-lung ventilation in children remains a specialized practice with low case numbers even at tertiary centers, preventing an assessment of best practices. The authors hypothesized that certain case factors may be associated with a higher risk of intraprocedural hypoxemia in children undergoing thoracic surgery and one-lung ventilation.

METHODS

The Multicenter Perioperative Outcomes database and a local quality improvement database were queried for documentation of one-lung ventilation in children 2 months to 3 yr of age inclusive between 2010 and 2020. Patients undergoing vascular or other cardiac procedures were excluded. All records were reviewed electronically for the presence of hypoxemia, oxygen saturation measured by pulse oximetry (Spo2) less than 90% for 3 min or more continuously, and severe hypoxemia, Spo2 less than 90% for 5 min or more continuously during one-lung ventilation. Records were also assessed for hypercarbia, end-tidal CO2 greater than 60 mmHg for 5 min or more or a Paco2 greater than 60 on arterial blood gas. Covariates assessed for association with these outcomes included age, weight, American Society of Anesthesiologists (Schaumburg, Illinois) Physical Status 3 or greater, duration of one-lung ventilation, preoperative Spo2 less than 98%, bronchial blocker versus endobronchial intubation, left operative side, video-assisted thoracoscopic surgery, lower tidal volume ventilation (tidal volume less than or equal to 6 ml/kg plus positive end expiratory pressure greater than or equal to 4 cm H2O for more than 80% of the duration of one-lung ventilation), and type of procedure.

RESULTS

Three hundred six cases from 15 institutions were included for analysis. Hypoxemia and severe hypoxemia occurred in 81 of 306 (26%) patients and 56 of 306 (18%), respectively. Hypercarbia occurred in 153 of 306 (50%). Factors associated with lower risk of hypoxemia in multivariable analysis included left operative side (odds ratio, 0.45 [95% CI, 0.251 to 0.78]) and bronchial blocker use (odds ratio, 0.351 [95% CI, 0.177 to 0.67]). Additionally, use of a bronchial blocker was associated with a reduced risk of severe hypoxemia (odds ratio, 0.290 [95% CI, 0.125 to 0.62]).

CONCLUSIONS

Use of a bronchial blocker was associated with a lower risk of hypoxemia in young children undergoing one-lung ventilation.

EDITOR’S PERSPECTIVE

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.

Anesthetic Management for Pulmonary Resection: Current Concepts and Improving Safety of Anesthesia

Increasingly complex procedures are routinely performed using minimally invasive approaches, allowing cancers to be resected with short hospital stays, minimal postsurgical discomfort, and improved odds of cancer-free survival. Along with these changes, the focus of anesthetic management for lung resection surgery has expanded from the provision of ideal surgical conditions and safe intraoperative patient care to include preoperative patient training and optimization and postoperative pain management techniques that can impact pulmonary outcomes as well as patient lengths of stay.

A Comparison Between Selective Lobar Bronchial Blockade and Main Bronchial Blockade in Pediatric Thoracoscopic Surgery: A Retrospective Cohort Study

OBJECTIVE

The primary objective of this study was to assess the effect of selective lobar blockade on the risk of hypoxemia during one-lung ventilation in pediatric patients undergoing thoracoscopic surgery.

DESIGN

This was a retrospective matched case-control cohort study.

SETTING

The study was performed in a teaching hospital.

PARTICIPANTS

A total of 60 pediatric patients who underwent thoracoscopic surgery in the authors' hospital from March 2020 to March 2021 were analyzed.

INTERVENTIONS

The authors examined their electronic medical records and found 30 patients in whom selective lobar blockade was used. These patients then were matched to 30 other patients in whom routine main bronchial blockade was performed in the authors' center based on age, weight, sex, side of surgery, and type of surgery.

MEASUREMENTS AND MAIN RESULTS

The inclusion criteria were four-fold: (1) pediatric patients with scheduled thoracoscopic resection of the middle and lower lobe lesions; (2) no obvious anesthesia or surgical contraindications; (3) American Society of Anesthesiologists class I to II; and (4) age younger than one year old. The exclusion criteria were as follows: (1) pediatric patients whose trachea was intubated with a size less than 3.0 mm; (2) a difficult airway; (3) changes in ventilation patterns during surgery; and (4) severe pneumonia and respiratory and circulatory system dysfunction. The following patient data were collected: (1) general clinical information; (2) mean arterial blood pressure, heart rate, central venous pressure, airway peak pressure (Ppeak), oxygenation index (PaO₂/F_IO₂ ratio), and alveolar-arterial oxygen differential pressure (AaDO2) at different time points; that is, before one-lung ventilation (OLV) (T1), ten minutes after OLV (T2), and ten minutes after the end of OLV (T3); (3) degree of lung collapse ten minutes after OLV; (4) operative duration; and (5) the prevalence of hypoxemia, the number of adjustments required for intraoperative displacement of the bronchial blocker, and pulmonary atelectasis. A total of 135 patients were selected, and 60 pediatric patients (30 in group S and 30 in group R) were included in this study. There were no significant differences in age, sex, weight, general preoperative data, degree of lung collapse, or operative duration (p > 0.05). The perioperative hemodynamics between the two groups were not statistically significant (p > 0.05). The oxygenation index, AaDO2, and Ppeak were not significantly different between the two groups at the T1 time point (p > 0.05). However, the oxygenation index was higher, and AaDO2 and Ppeak were lower in group S than in group R at the T2 and T3 time points (p < 0.05). The incidence of atelectasis, the prevalence of hypoxemia, and the number of adjustments required for intraoperative displacement of the bronchial blocker in group S were lower than those in group R (p < 0.05).

CONCLUSION

Selective lobar bronchial blockade, using a bronchial blocker in pediatric thoracoscopic surgery, may represent an alternative to excluding the main bronchial blockade for patients undergoing middle and lower lobe procedures, which may improve intraoperative oxygenation and reduce postoperative atelectasis.

Application of Continuous Positive Airway Pressure During Video-Assisted Thoracoscopic Surgery

Purpose of Review

Video-assisted thoracoscopic surgery (VATS) and robotic-assisted thoracoscopic surgery (RATS) are used for anatomic resection of early stage cancer. These surgical techniques require the use of one-lung ventilation (OLV). During OLV, an obligatory intrapulmonary shunt may produce hypoxemia. One method to correct hypoxemia is with the use of continuous positive airway pressure (CPAP). This review focuses on 1) the lung physiology of OLV; 2) application of CPAP in VATS or RATS during supine and lateral position; and 3) the application of CPAP in COVID-19 patients during OLV.

Recent Findings

Studies have shown the beneficial effects of CPAP to improve oxygenation during OLV while the patient is in the lateral decubitus position. In contrast, studies have shown no benefit on improving oxygenation with CPAP in patients undergoing OLV in supine position.

Summary

The application of CPAP to the non-dependent lung is one of the options to treat hypoxemia during VATS or RATS.

Hypoxemia During One-Lung Ventilation: Does It Really Matter?

PURPOSE OF REVIEW

Hypoxemia during one-lung ventilation, while decreasing in frequency, persists as an intraoperative challenge for anesthesiologists. Discerning when desaturation and resultant hypoxemia correlates to tissue hypoxia is challenging in the perioperative setting and requires a thorough understanding of the physiology of oxygen delivery and tissue utilization.

RECENT FINDINGS

Oxygen delivery is not directly correlated with peripheral oxygen saturation in patients undergoing one-lung ventilation, emphasizing the importance of hemoglobin concentration and cardiac output in avoiding tissue hypoxia. While healthy humans can tolerate acute hypoxemia without long-term consequences, there is a paucity of evidence from patients undergoing thoracic surgery. Increasingly recognized is the potential harm of hyperoxic states, particularly in the setting of complex patients with comorbid diseases.

SUMMARY

Anesthesiologists are left to determine an acceptable oxygen saturation nadir that is individualized to the patient and procedure based on an understanding of oxygen supply, demand, and the consequences of interventions.

[Intraoperative Ventilation Approaches to One-lung Ventilation]

The management of thoracic surgery patients is challenging to the anesthetist, since one-lung ventilation (OLV) includes at least two major conditions: sufficient oxygenation and lung protection. The first is mainly because the ventilation of one lung is stopped while perfusion to that lung continues; the latter is related to the fact that the whole ventilation is applied to only a single lung. Recommendations for maintaining the oxygenation and methods of lung protection may contradict each other (e. g. high vs. low inspiratory oxygen fraction (FiO₂), high vs. low tidal volume, etc.). Therefore, a high degree of pathophysiological understanding and manual skills are required in the management of these patients.In light of recent clinical studies, this review focuses on a current protective strategy for OLV, which includes a possible decrease in FiO₂, lowered V_T, the application of positive end-expiratory pressure (PEEP) to the dependent and continuous positive airway pressure (CPAP) to the non-dependent lung and alveolar recruitment manoeuvres as well. Other approaches such as the choice of anaesthetics, remote ischemic preconditioning, fluid management and pain therapy can support the success of ventilatory strategy. The present work describes new developments that may change the classical approach in this respect.

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

Selective right middle and lower lobar blockade for minimally invasive cardiac surgery: a prospective, single-center, randomized controlled study

Background

Minimally invasive cardiac surgery (MICS) is increasingly performed due to faster recovery time and lower postoperative complications when compared with the traditional open surgery. However, hypoxemia in lung isolation duration after cardiopulmonary bypass (CPB) surgery has been the focus of anesthesiologists' attention. In the present study, we designed a novel lung isolation strategy to improve oxygenation using a bronchial blocker (BB) to isolate the right middle and lower lobes and preserve the ventilated right upper lobe without affecting the surgical field.

Methods

Patients who had undergone right lateral mini-thoracotomy, a MICS, between August 2018 and February 2019, were enrolled in this randomized controlled study. Patients were randomly divided into a modified lung isolation group (group M) and a conventional lung isolation group (group C). In group M, BBs were used to block the bronchus intermedius, while left-sided double lumen endotracheal tubes were used in group C to isolate the right lung. The primary outcome was to determine the number of patients who required an increase in ventilation volume due to hypoxemia during lung isolation after CPB.

Results

Sixty-one patients (30 in group C and 31 in group M) were enrolled. Five patients in group M were converted to right lung isolation due to poor surgical field exposure. During lung isolation after CPB, the number of patients with hypoxemia was lower in group M than group C (5/31 vs. 15/30, P=0.005).

Conclusions

The novel modified lung isolation strategy reduced the incidence of hypoxemia after CPB.

Comparative effects of flow vs. volume-controlled one-lung ventilation on gas exchange and respiratory system mechanics in pigs

Background

Flow-controlled ventilation (FCV) allows expiratory flow control, reducing the collapse of the airways during expiration. The performance of FCV during one-lung ventilation (OLV) under intravascular normo- and hypovolaemia is currently unknown. In this explorative study, we hypothesised that OLV with FCV improves PaO₂ and reduces mechanical power compared to volume-controlled ventilation (VCV). Sixteen juvenile pigs were randomly assigned to one of two groups: (1) intravascular normovolaemia (n = 8) and (2) intravascular hypovolaemia (n = 8). To mimic inflammation due to major thoracic surgery, a thoracotomy was performed, and 0.5 μg/kg/h lipopolysaccharides from Escherichia coli continuously administered intravenously. Animals were randomly assigned to OLV with one of two sequences (60 min per mode): (1) VCV–FCV or (2) FCV–VCV. Variables of gas exchange, haemodynamics and respiratory signals were collected 20, 40 and 60 min after initiation of OLV with each mechanical ventilation mode. The distribution of ventilation was determined using electrical impedance tomography (EIT).

Results

Oxygenation did not differ significantly between modes (P = 0.881). In the normovolaemia group, the corrected expired minute volume (P = 0.022) and positive end-expiratory pressure (PEEP) were lower during FCV than VCV. The minute volume (P ≤ 0.001), respiratory rate (P ≤ 0.001), total PEEP (P ≤ 0.001), resistance of the respiratory system (P ≤ 0.001), mechanical power (P ≤ 0.001) and resistive mechanical power (P ≤ 0.001) were lower during FCV than VCV irrespective of the volaemia status. The distribution of ventilation did not differ between both ventilation modes (P = 0.103).

Conclusions

In a model of OLV in normo- and hypovolemic pigs, mechanical power was lower during FCV compared to VCV, without significant differences in oxygenation. Furthermore, the efficacy of ventilation was higher during FCV compared to VCV during normovolaemia.

Effects of bronchial blockers on gas exchange in infants with one-lung ventilation: a single-institutional experience of 22 cases

BACKGROUND

One-lung ventilation (OLV) in infants is a commonly used airway technique during thoracic surgery. Current research has primarily focused on the operation of the airways and the occurrence of complications. However, there has been minimal data on the pulmonary gas exchange in infants before and after OLV. This study aimed to assess the efficacy of bronchial blockers (BBs) on the pulmonary gas exchange in infants with OLV.

METHODS

A total of 22 infants requiring OLV from January 2017 to August 2019 were included in this study. OLV was achieved by placing BBs outside the endotracheal tube, and all surgeries were performed by the same experienced anesthesiologist. Numerous clinical features, including the oxygenation index (OI), alveolar-arterial oxygen tension gradient (P_A-aO₂), pulmonary dynamic compliance (Cdyn), OLV time, pulmonary collapse time, degree of pulmonary collapse at the operative side, operative time, and immediate hemodynamic indexes before and after intubation were assessed. Data from the arterial blood gases and the ventilator's parameters were obtained at three time points: 15 minutes before OLV (pre-OLV), 15 minutes after the initiation of OLV (during OLV), and 15 minutes after the termination of OLV (post-OLV).

RESULTS

For all patients, the pulmonary gas exchange during OLV was significantly different from both pre-OLV and post-OLV. However, no significant changes of pulmonary function were observed before and after OLV. Extended OLV time was associated with decreased OI and Cdyn, and increased P_A-aO₂ gradient (P<0.001). In addition, no significant changes of hemodynamic indexes before and after intubation were detected. The degree of lung collapse on the operational side during OLV was optimal.

CONCLUSIONS

In this study, the efficacy of BBs on the pulmonary gas exchange in infants with OLV was assessed. The results suggested that although each parameter of pulmonary function pre-OLV were similar to those of post-OLV, an extended period of OLV may lead to compromised lung function.

A nationwide survey of intraoperative management for one-lung ventilation in Taiwan: time to accountable for diversity in protective lung ventilation

BACKGROUND

There is a major paradigm shift for intraoperative mechanical ventilator support by the introduction of lung protective ventilation strategies to reduce postoperative pulmonary complications and improve overall clinical outcomes in non-thoracic surgeries. However, there is currently a lack of standardized practice guideline for lung protection during thoracic surgeries that require one-lung ventilation (OLV). This study aimed to collect the expert opinions of the thoracic anesthesiologists in perioperative care for OLV surgery in Taiwan.

METHODS

This prospective cross-sectional study was undertaken in 16 tertiary hospitals in Taiwan from January to February 2019. A structured survey form was distributed across the participating hospitals and the thoracic anesthesiologists were invited to complete the form voluntarily. The survey form consisted of three parts, including the basic information of the institutional anesthesia care standards, ventilatory settings for a proposed patient receiving OLV surgery and expert opinions on OLV.

RESULTS

A total of 71 thoracic anesthesiologists responded to the survey. Double-lumen tubes are the most commonly used (93.8%) airway devices for OLV. The most commonly recommended ventilator setting during OLV is a tidal volume of 6-7 ml/kg PBW (67.6%) and a PEEP level of 4-6 cmH₂O (73.5%). Dual controlled ventilator modes are used by 44.1% of the anesthesiologists. During OLV, high oxygen fraction (FiO₂ > 0.8) is more commonly supplemented to achieve an oxygen saturation higher than 94%. The consensus of anesthesiologists on the indices for lung protection in thoracic surgery is considerably low. Large majority of the anesthesiologists (91.5%) highly recommend that an international clinical practice guideline on the protective lung ventilation strategy for thoracic anesthesia should be established.

CONCLUSIONS

This study found that the thoracic anesthesiologists in Taiwan share certain common practices in ventilator support during OLV. However, they are concerned about the lack of fundamental clinical evidences to support the beneficial outcomes of the current lung protective strategies applicable to OLV. Large-scale trials are needed to form an evidence-based clinical practice guideline for thoracic anesthesia.

Feasibility and efficacy of lung ultrasound to investigate pulmonary complications in patients who developed postoperative Hypoxaemia-a prospective study

Background

Postoperative pulmonary complications (PPCs) and hypoxaemia are associated with morbidity and mortality. We aimed to evaluate the feasibility and efficacy of lung ultrasound (LUS) to diagnose PPCs in patients suffering from hypoxaemia after general anaesthesia and compare the results to those of thoracic computed tomography (CT).

Methods

Adult patients who received general anaesthesia and suffered from hypoxaemia in the postanaesthesia care unit (PACU) were analysed. Hypoxaemia was defined as an oxygen saturation measured by pulse oximetry (SPO₂) less than 92% for more than 30 s under ambient air conditions. LUS was performed by two trained anaesthesiologists once hypoxaemia occurred. After LUS examination, each patient was transported to the radiology department for thoracic CT scan within 1 h before returning to the ward.

Results

From January 2019 to May 2019, 113 patients (61 men) undergoing abdominal surgery (45 patients, 39.8%), video-assisted thoracic surgery (31 patients, 27.4%), major orthopaedic surgery (17 patients, 15.0%), neurosurgery (10 patients, 8.8%) or other surgery (10 patients, 8.8%) were included. CT diagnosed 327 of 1356 lung zones as atelectasis, while LUS revealed atelectasis in 311 of the CT-confirmed zones. Pneumothorax was detected by CT scan in 75 quadrants, 72 of which were detected by LUS. Pleural effusion was diagnosed in 144 zones on CT scan, and LUS detected 131 of these zones. LUS was reliable in diagnosing atelectasis (sensitivity 98.0%, specificity 96.7% and diagnostic accuracy 97.2%), pneumothorax (sensitivity 90.0%, specificity 98.9% and diagnostic accuracy 96.7%) and pleural effusion (sensitivity 92.9%, specificity 96.0% and diagnostic accuracy 95.1%).

Conclusions

Lung ultrasound is feasible, efficient and accurate in diagnosing different aetiologies of postoperative hypoxia in healthy-weight patients in the PACU.

Trial registration

Current Controlled Trials NCT03802175, 2018/12/05, www.ClinicalTrials.gov

[Inverse ratio ventilation combined with PEEP in infants undergoing thoracoscopic surgery with one lung ventilation for lung cystadenomas: a randomized control trial of 63 cases]

OBJECTIVE

To investigate the effect of inverse ratio ventilation (IRV) combined with positive end-expiratory pressure (PEEP) in infants undergoing thoracoscopic surgery with single lung ventilation (OLV) for lung cystadenomas.

METHODS

A total of 66 infants undergoing thoracoscopic surgery with OLV for lung cystadenomas in our hospital from February, 2018 to February, 2019 were randomized into conventional ventilation groups (group N, n=33) and inverse ventilation group (group R, n=33). Hemodynamics and respiratory parameters of the infants were recorded and arterial blood gas analysis was performed at 15 min after two lung ventilation (TLV) (T₁), OLV30 min (T₂), OLV60 min (T₃), and 15 min after recovery of TLV (T₄). Bronchoalveolar lavage fluid was collected before and after surgery to detect the expression level of advanced glycation end product receptor (RAGE).

RESULTS

Sixty-three infants were finally included in this study. At T₂ and T₃, Cdyn, PaO₂ and OI in group R were significantly higher (P &lt; 0.05) and Ppeak, PaCO₂ and PA-aO₂ were significantly lower than those in group N (P &lt; 0.05). There was no significant difference in HR or MAP between the two groups at T₂ and T₃ (P &gt; 0.05). The level of RAGE significantly increased after the surgery in both groups (P &lt; 0.05), and was significantly lower in R group than in N group (P &lt; 0.05).

CONCLUSIONS

In infants undergoing thoracoscopic surgery with OLV for pulmonary cystadenoma, appropriate IRV combined with PEEP does not affect hemodynamic stability and can increases pulmonary compliance, reduce the peak pressure, and improve oxygenation to provide pulmonary protection.

The anaesthetic management of patients with thoracic ascending aortic aneurysms: A review

Thoracic aortic aneurysms present significant challenges to clinicians, especially due to their complex nature and an evolving understanding of the safest and most effective ways to manage this condition in the perioperative setting. Thoracic aortic aneurysms have a prevalence rate of 1.3-8.9% in men and 1.0-2.2% in women, and they are estimated to affect more than five per 100,000 person-years. This is notable because the complications of thoracic aortic aneurysms can be catastrophic. The current understanding of the optimal intraoperative management of thoracic aortic aneurysms is changing, as more evidence becomes available regarding lung protective ventilation and its role in enhancing patient safety and wellbeing. This review strives to provide a brief historical understanding of thoracic aortic aneurysms and highlight some of the key discoveries and advances in the management of this condition. This review then describes an overview of the general anaesthetic principles associated with thoracic aortic aneurysms, including ventilatory modalities and how these impact a patient's physiology and intraoperative haemodynamics. A brief discussion on one-lung ventilation is then provided, drawing from current literature in the field, to describe the most up-to-date management of thoracic aortic aneurysms.

Intraoperative Anesthetic Management of the Thoracic Patient

The intraoperative anesthetic management for thoracic surgery can impact a patient's postoperative course, especially in patients with significant lung disease. One-lung ventilation poses an inherent risk to patients, including hypoxemia, acute lung injury, and right ventricular dysfunction. Patient-specific ventilator management strategies during one-lung ventilation can reduce postoperative morbidity.