Protective Ventilation during Anesthesia

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

Randomised controlled trial.

SETTING

First Medical Centre of Chinese PLA General Hospital, Beijing.

PATIENTS

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

INTERVENTIONS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION

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

Assessment of Regional Ventilation During Recruitment Maneuver by Electrical Impedance Tomography in Dogs

Background

During protective mechanical ventilation, electrical impedance tomography (EIT) is used to monitor alveolar recruitment maneuvers as well as the distribution of regional ventilation. This technique can infer atelectasis and lung overdistention during mechanical ventilation in anesthetized patients or in the ICU. Changes in lung tissue stretching are evaluated by monitoring the electrical impedance of lung tissue with each respiratory cycle.

Objective

This study aimed to evaluate the distribution of regional ventilation during recruitment maneuvers based on the variables obtained in pulmonary electrical impedance tomography during protective mechanical ventilation, focusing on better lung recruitment associated with less or no overdistention.

Methods

Prospective clinical study using seven adult client–owned healthy dogs, weighing 25 ± 6 kg, undergoing elective ovariohysterectomy or orchiectomy. The animals were anesthetized and ventilated in volume-controlled mode (7 ml.kg⁻¹) with stepwise PEEP increases from 0 to 20 cmH₂O in steps of 5 cmH₂O every 5 min and then a stepwise decrease. EIT, respiratory mechanics, oxygenation, and hemodynamic variables were recorded for each PEEP step.

Results

The results show that the regional compliance of the dependent lung significantly increased in the PEEP 10 cmH₂O decrease step when compared with baseline (p < 0.027), and for the nondependent lung, there was a decrease in compliance at PEEP 20 cmH₂O (p = 0.039) compared with baseline. A higher level of PEEP was associated with a significant increase in silent space of the nondependent regions from the PEEP 10 cmH₂O increase step (p = 0.048) until the PEEP 15 cmH₂O (0.019) decrease step with the highest values at PEEP 20 cmH₂0 (p = 0.016), returning to baseline values thereafter. Silent space of the dependent regions did not show any significant changes. Drive pressure decreased significantly in the PEEP 10 and 5 cmH₂O decrease steps (p = 0.032) accompanied by increased respiratory static compliance in the same PEEP step (p = 0.035 and 0.018, respectively).

Conclusions

The regional ventilation distribution assessed by EIT showed that the best PEEP value for recruitment maintenance, capable of decreasing areas of pulmonary atelectasis in dependent regions promoting less overinflation in nondependent areas, was from 10 to 5 cmH₂O decreased steps.

Pressure Support versus Spontaneous Ventilation during Anesthetic Emergence-Effect on Postoperative Atelectasis: A Randomized Controlled Trial

BACKGROUND

Despite previous reports suggesting that pressure support ventilation facilitates weaning from mechanical ventilation in the intensive care unit, few studies have assessed its effects on recovery from anesthesia. The authors hypothesized that pressure support ventilation during emergence from anesthesia reduces postoperative atelectasis in patients undergoing laparoscopic surgery using the Trendelenburg position.

METHODS

In this randomized controlled double-blinded trial, adult patients undergoing laparoscopic colectomy or robot-assisted prostatectomy were assigned to either the pressure support (n = 50) or the control group (n = 50). During emergence (from the end of surgery to extubation), pressure support ventilation was used in the pressure support group versus intermittent manual assistance in the control group. The primary outcome was the incidence of atelectasis diagnosed by lung ultrasonography at the postanesthesia care unit (PACU). The secondary outcomes were Pao2 at PACU and oxygen saturation measured by pulse oximetry less than 92% during 48 h postoperatively.

RESULTS

Ninety-seven patients were included in the analysis. The duration of emergence was 9 min and 8 min in the pressure support and control groups, respectively. The incidence of atelectasis at PACU was lower in the pressure support group compared to that in the control group (pressure support vs. control, 16 of 48 [33%] vs. 28 of 49 [57%]; risk ratio, 0.58; 95% CI, 0.35 to 0.91; P = 0.024). In the PACU, Pao2 in the pressure support group was higher than that in the control group (92 ± 26 mmHg vs. 83 ± 13 mmHg; P = 0.034). The incidence of oxygen saturation measured by pulse oximetry less than 92% during 48 h postoperatively was not different between the groups (9 of 48 [19%] vs. 11 of 49 [22%]; P = 0.653). There were no adverse events related to the study protocol.

CONCLUSIONS

The incidence of postoperative atelectasis was lower in patients undergoing either laparoscopic colectomy or robot-assisted prostatectomy who received pressure support ventilation during emergence from general anesthesia compared to those receiving intermittent manual assistance.

EDITOR’S PERSPECTIVE

Anesthetic Management of a Rett Syndrome Patient at High Risk for Respiratory Complications

Rett syndrome (RTT) is a rare genetic disorder that can present challenges in airway management during general anesthesia. This is a case report involving a 23-year-old woman with RTT who received an intubated general anesthetic 3 times for dental treatment. The patient also had severe scoliosis, was bedridden, and had dysphagia. These contributing factors likely led to the development of postoperative respiratory complications including pneumonia after the first case. As a result, several changes were incorporated into the 2 subsequent anesthetic plans in efforts to reduce the risk of such complications. Despite these measures, the patient was suspected of having bronchitis postoperatively after the second anesthetic, although the third occurred uneventfully. Anesthetic management alterations included use of desflurane for anesthetic maintenance and postoperatively delaying oral intake and instituting active postural changes.

Individualized positive end-expiratory pressure (PEEP) during one-lung ventilation for prevention of postoperative pulmonary complications in patients undergoing thoracic surgery: A meta-analysis

BACKGROUND

Positive end-expiratory pressure (PEEP) is an important part of the lung protection strategies for one-lung ventilation (OLV). However, a fixed PEEP value is not suitable for all patients. Our objective was to determine the prevention of individualized PEEP on postoperative complications in patients undergoing one-lung ventilation.

METHOD

We searched the PubMed, Embase, and Cochrane and performed a meta-analysis to compare the effect of individual PEEP vs fixed PEEP during single lung ventilation on postoperative pulmonary complications. Our primary outcome was the occurrence of postoperative pulmonary complications during follow-up. Secondary outcomes included the partial pressure of arterial oxygen and oxygenation index during one-lung ventilation.

RESULT

Eight studies examining 849 patients were included in this review. The rate of postoperative pulmonary complications was reduced in the individualized PEEP group with a risk ratio of 0.52 (95% CI:0.37-0.73; P = .0001). The partial pressure of arterial oxygen during the OLV in the individualized PEEP group was higher with a mean difference 34.20 mm Hg (95% CI: 8.92-59.48; P = .0004). Similarly, the individualized PEEP group had a higher oxygenation index, MD: 49.07mmHg, (95% CI: 27.21-70.92; P < .0001).

CONCLUSIONS

Individualized PEEP setting during one-lung ventilation in patients undergoing thoracic surgery was associated with fewer postoperative pulmonary complications and better perioperative oxygenation.

[Pathogenic role leukotriene B4 in lung injury induced by lung-protective mechanical ventilation in rabbits]

OBJECTIVE

To elucidate the pathogenic role of leukotriene B4 (LTB4) in pulmonary hyper-permeability and inflammation induced by lung-protective mechanical ventilation (LPMV) in rabbits.

METHODS

Thirty-two healthy Japanese white rabbits were randomized into 4 groups for treatment with vehicle or bestatin (a leukotriene A4 hydrolase inhibitor that inhibits LTB4 production) administered intragastrically at the daily dose of 8 mg/kg for 5 days, followed by sham operation (group S and group BS, respectively, in which the rabbits were anesthetized only) or LPMV (group PM and group BPM, respectively, in which the rabbits received ventilation with 50% oxygen at a tidal volume of 8 mL/kg for 5 h). The concentrations of LTB4 and cyclic adenosine monophosphate (cAMP) in the lung tissues were analyzed by ELISA. cAMP content, protein kinase A (PKA) protein expression and the Rap1-GTP protein to total Rap1 protein ratio were determined to assess the activities of cAMP/PKA and Rap1 signaling pathways. The lung injury was evaluated by assessing lung permeability index, lung wet/dry weight ratio, polymorphonuclear leukocyte (PMN) count in bronchoalveolar lavage fluid (BALF), pulmonary myeloperoxidase (MPO) activity and lung histological scores.

RESULTS

None of the examined parameters differed significantly between group S and group BS. All the parameters with the exception of lung histological score increased significantly in group PM and group BPM as compared to those in group S (P < 0.05). Compared with those in PM group, the rabbits in group BPM showed significantly reduced LTB4 production in the lungs (P < 0.05), up-regulated cAMP/ PKA and Rap1 signaling pathway activities (P < 0.05), and alleviated lung hyper-permeability and inflammation (P < 0.05).

CONCLUSIONS

LPMV can induce LTB4 overproduction to down-regulate cAMP/PKA and Rap1 signaling pathways in the lungs of rabbits, which results in lung hyper-permeability and inflammation. Bestatin can inhibit LTB4 production in the lungs to protect against LPMV-induced lung hyper-permeability and inflammation.

Effects of inspired oxygen concentration during emergence from general anaesthesia on postoperative lung impedance changes evaluated by electrical impedance tomography: a randomised controlled trial

We evaluated the effects of three different inspired oxygen concentrations (40%, 80%, and 100%) at anaesthesia emergence on postoperative lung volumes as measured by global impedance of electrical impedance tomography (EIT). This is a randomised, controlled, and assessor-blinded study in single-centre from May 2017 to August 2017. Seventy-one patients undergoing elective laparoscopic colorectal surgery with healthy lung condition were randomly allocated into the three groups based on the concentration of inspired oxygen applied during anaesthesia emergence: 40%-, 80%- or 100%-oxygen. End-expiratory lung impedance (EELI) with normal tidal ventilation and total lung impedance (TLI) with full respiratory effort were measured preoperatively and before discharge in the post-anaesthesia care unit by EIT, and perioperative changes (the ratio of difference between preoperative and postoperative value to preoperative value) were compared among the three groups. Postoperative lung impedances were significantly reduced compared with preoperative values in all patients (P < 0.001); however, perioperative lung impedance reduction (%) did not differ among the three oxygen groups. The mean reduction ratio in each 40%-, 80%-, and 100%-oxygen group were 37% ± 13%, 41% ± 14%, and 46% ± 14% for EELI (P = 0.125) and 40% ± 20%, 44% ± 17% and 49% ± 20% for TLI (P = 0.276), respectively. Inspired oxygen concentrations applied during anaesthesia emergence did not show a significant difference in postoperative lung volume as measured by EIT in patients undergoing laparoscopic colorectal surgery with healthy lungs.Trial registration cris.nih.go.kr (KCT0002642).

Deterioration of Regional Lung Strain and Inflammation during Early Lung Injury

RATIONALE

The contribution of aeration heterogeneity to lung injury during early mechanical ventilation of uninjured lungs is unknown.

OBJECTIVES

To test the hypotheses that a strategy consistent with clinical practice does not protect from worsening in lung strains during the first 24 hours of ventilation of initially normal lungs exposed to mild systemic endotoxemia in supine versus prone position, and that local neutrophilic inflammation is associated with local strain and blood volume at global strains below a proposed injurious threshold.

METHODS

Voxel-level aeration and tidal strain were assessed by computed tomography in sheep ventilated with low Vt and positive end-expiratory pressure while receiving intravenous endotoxin. Regional inflammation and blood volume were estimated from 2-deoxy-2-[(18)F]fluoro-d-glucose (¹⁸F-FDG) positron emission tomography.

MEASUREMENTS AND MAIN RESULTS

Spatial heterogeneity of aeration and strain increased only in supine lungs (P < 0.001), with higher strains and atelectasis than prone at 24 hours. Absolute strains were lower than those considered globally injurious. Strains redistributed to higher aeration areas as lung injury progressed in supine lungs. At 24 hours, tissue-normalized ¹⁸F-FDG uptake increased more in atelectatic and moderately high-aeration regions (>70%) than in normally aerated regions (P < 0.01), with differential mechanistically relevant regional gene expression. ¹⁸F-FDG phosphorylation rate was associated with strain and blood volume. Imaging findings were confirmed in ventilated patients with sepsis.

CONCLUSIONS

Mechanical ventilation consistent with clinical practice did not generate excessive regional strain in heterogeneously aerated supine lungs. However, it allowed worsening of spatial strain distribution in these lungs, associated with increased inflammation. Our results support the implementation of early aeration homogenization in normal lungs.

Individual Positive End-expiratory Pressure Settings Optimize Intraoperative Mechanical Ventilation and Reduce Postoperative Atelectasis

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Intraoperative lung-protective ventilation has been recommended to reduce postoperative pulmonary complications after abdominal surgery. Although the protective role of a more physiologic tidal volume has been established, the added protection afforded by positive end-expiratory pressure (PEEP) remains uncertain. The authors hypothesized that a low fixed PEEP might not fit all patients and that an individually titrated PEEP during anesthesia might improve lung function during and after surgery.

METHODS

Forty patients were studied in the operating room (20 laparoscopic and 20 open-abdominal). They underwent elective abdominal surgery and were randomized to institutional PEEP (4 cm H2O) or electrical impedance tomography-guided PEEP (applied after recruitment maneuvers and targeted at minimizing lung collapse and hyperdistension, simultaneously). Patients were extubated without changing selected PEEP or fractional inspired oxygen tension while under anesthesia and submitted to chest computed tomography after extubation. Our primary goal was to individually identify the electrical impedance tomography-guided PEEP value producing the best compromise of lung collapse and hyperdistention.

RESULTS

Electrical impedance tomography-guided PEEP varied markedly across individuals (median, 12 cm H2O; range, 6 to 16 cm H2O; 95% CI, 10-14). Compared with PEEP of 4 cm H2O, patients randomized to the electrical impedance tomography-guided strategy had less postoperative atelectasis (6.2 ± 4.1 vs. 10.8 ± 7.1% of lung tissue mass; P = 0.017) and lower intraoperative driving pressures (mean values during surgery of 8.0 ± 1.7 vs. 11.6 ± 3.8 cm H2O; P < 0.001). The electrical impedance tomography-guided PEEP arm had higher intraoperative oxygenation (435 ± 62 vs. 266 ± 76 mmHg for laparoscopic group; P < 0.001), while presenting equivalent hemodynamics (mean arterial pressure during surgery of 80 ± 14 vs. 78 ± 15 mmHg; P = 0.821).

CONCLUSIONS

PEEP requirements vary widely among patients receiving protective tidal volumes during anesthesia for abdominal surgery. Individualized PEEP settings could reduce postoperative atelectasis (measured by computed tomography) while improving intraoperative oxygenation and driving pressures, causing minimum side effects.

Specific anesthesia-induced lung volume changes from induction to emergence: a pilot study

BACKGROUND

Studies aimed at maintaining intraoperative lung volume to reduce post-operative pulmonary complications have been inconclusive because they mixed up the effect of general anesthesia and the surgical procedure. Our aims were to study: (1) lung volume during the entire course of anesthesia without the confounding effects of surgical procedures; (2) the combination of three interventions to maintain lung volume; and (3) the emergence phase with focus on the restored activation of the respiratory muscles.

METHODS

Eighteen ASA I-II patients undergoing ENT surgery under general anesthesia without muscle relaxants were randomized to an intervention group, receiving lung recruitment maneuver (LRM) after induction, 7 cmH₂ O positive end-expiratory pressure (PEEP) during anesthesia and continuous positive airway pressure (CPAP) during emergence with 0.4 inspired oxygen fraction (FiO₂ ) or a control group, ventilated without LRM, with 0 cmH₂ O PEEP, and 1.0 FiO₂ during emergence without CPAP application. End-expiratory lung volume (EELV) was continuously estimated by opto-electronic plethysmography. Inspiratory and expiratory ribcage muscles electromyography was measured in a subset of seven patients.

RESULTS

End-expiratory lung volume decreased after induction in both groups. It remained low in the control group and further decreased at emergence, because of active expiratory muscle contraction. In the intervention group, EELV increased after LRM and remained high after extubation.

CONCLUSION

A combined intervention consisting of LRM, PEEP and CPAP during emergence may effectively maintain EELV during anesthesia and even after extubation. An unexpected finding was that the activation of the expiratory muscles may contribute to EELV reduction during the emergence phase.

Impact of a Novel Multiparameter Decision Support System on Intraoperative Processes of Care and Postoperative Outcomes

Background

The authors hypothesized that a multiparameter intraoperative decision support system with real-time visualizations may improve processes of care and outcomes.

Methods

Electronic health record data were retrospectively compared over a 6-yr period across three groups: experimental cases, in which the decision support system was used for 75% or more of the case at sole discretion of the providers; parallel controls (system used 74% or less); and historical controls before system implementation. Inclusion criteria were adults under general anesthesia, advanced medical disease, case duration of 60 min or longer, and length of stay of two days or more. The process measures were avoidance of intraoperative hypotension, ventilator tidal volume greater than 10 ml/kg, and crystalloid administration (ml · kg–1 · h–1). The secondary outcome measures were myocardial injury, acute kidney injury, mortality, length of hospital stay, and encounter charges.

Results

A total of 26,769 patients were evaluated: 7,954 experimental cases, 10,933 parallel controls, and 7,882 historical controls. Comparing experimental cases to parallel controls with propensity score adjustment, the data demonstrated the following medians, interquartile ranges, and effect sizes: hypotension 1 (0 to 5) versus 1 (0 to 5) min, P &lt; 0.001, beta = –0.19; crystalloid administration 5.88 ml · kg–1 · h–1 (4.18 to 8.18) versus 6.17 (4.32 to 8.79), P &lt; 0.001, beta = –0.03; tidal volume greater than 10 ml/kg 28% versus 37%, P &lt; 0.001, adjusted odds ratio 0.65 (0.53 to 0.80); encounter charges $65,770 ($41,237 to $123,869) versus $69,373 ($42,101 to $132,817), P &lt; 0.001, beta = –0.003. The secondary clinical outcome measures were not significantly affected.

Conclusions

The use of an intraoperative decision support system was associated with improved process measures, but not postoperative clinical outcomes.

Individualised perioperative open-lung approach versus standard protective ventilation in abdominal surgery (iPROVE): a randomised controlled trial

BACKGROUND

The effects of individualised perioperative lung-protective ventilation (based on the open-lung approach [OLA]) on postoperative complications is unknown. We aimed to investigate the effects of intraoperative and postoperative ventilatory management in patients scheduled for abdominal surgery, compared with standard protective ventilation.

METHODS

We did this prospective, multicentre, randomised controlled trial in 21 teaching hospitals in Spain. We enrolled patients who were aged 18 years or older, were scheduled to have abdominal surgery with an expected time of longer than 2 h, had intermediate-to-high-risk of developing postoperative pulmonary complications, and who had a body-mass index less than 35 kg/m². Patients were randomly assigned (1:1:1:1) online to receive one of four lung-protective ventilation strategies using low tidal volume plus positive end-expiratory pressure (PEEP): open-lung approach (OLA)-iCPAP (individualised intraoperative ventilation [individualised PEEP after a lung recruitment manoeuvre] plus individualised postoperative continuous positive airway pressure [CPAP]), OLA-CPAP (intraoperative individualised ventilation plus postoperative CPAP), STD-CPAP (standard intraoperative ventilation plus postoperative CPAP), or STD-O₂ (standard intraoperative ventilation plus standard postoperative oxygen therapy). Patients were masked to treatment allocation. Investigators were not masked in the operating and postoperative rooms; after 24 h, data were given to a second investigator who was masked to allocations. The primary outcome was a composite of pulmonary and systemic complications during the first 7 postoperative days. We did the primary analysis using the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02158923.

FINDINGS

Between Jan 2, 2015, and May 18, 2016, we enrolled 1012 eligible patients. Data were available for 967 patients, whom we included in the final analysis. Risk of pulmonary and systemic complications did not differ for patients in OLA-iCPAP (110 [46%] of 241, relative risk 0·89 [95% CI 0·74-1·07; p=0·25]), OLA-CPAP (111 [47%] of 238, 0·91 [0·76-1·09; p=0·35]), or STD-CPAP groups (118 [48%] of 244, 0·95 [0·80-1·14; p=0·65]) when compared with patients in the STD-O₂ group (125 [51%] of 244). Intraoperatively, PEEP was increased in 69 (14%) of patients in the standard perioperative ventilation groups because of hypoxaemia, and no patients from either of the OLA groups required rescue manoeuvres.

INTERPRETATION

In patients who have major abdominal surgery, the different perioperative open lung approaches tested in this study did not reduce the risk of postoperative complications when compared with standard lung-protective mechanical ventilation.

FUNDING

Instituto de Salud Carlos III of the Spanish Ministry of Economy and Competitiveness, and Grants Programme of the European Society of Anaesthesiology.

Protective Lung Ventilation and Morbidity After Pulmonary Resection: A Propensity Score-Matched Analysis

BACKGROUND

Protective lung ventilation (PLV) during one-lung ventilation (OLV) for thoracic surgery is frequently recommended to reduce pulmonary complications. However, limited outcome data exist on whether PLV use during OLV is associated with less clinically relevant pulmonary morbidity after lung resection.

METHODS

Intraoperative data were prospectively collected in 1080 patients undergoing pulmonary resection with OLV, intentional crystalloid restriction, and mechanical ventilation to maintain inspiratory peak airway pressure <30 cm H2O. Other ventilator settings and all aspects of anesthetic management were at the discretion of the anesthesia care team. We defined PLV and non-PLV as <8 or ≥8 mL/kg (predicted body weight) mean tidal volume. The primary outcome was the occurrence of pneumonia and/or acute respiratory distress syndrome (ARDS). Propensity score matching was used to generate PLV and non-PLV groups with comparable characteristics. Associations between outcomes and PLV status were analyzed by exact logistic regression, with matching as cluster in the anatomic and nonanatomic lung resection cohorts.

RESULTS

In the propensity score-matched analysis, the incidence of pneumonia and/or ARDS among patients who had an anatomic lung resection was 9/172 (5.2%) in the non-PLV compared to the PLV group 7/172 (4.1%; odds ratio, 1.29; 95% confidence interval, 0.48-3.45, P= .62). The incidence of pneumonia and/or ARDS in patients who underwent nonanatomic resection was 3/118 (2.5%) in the non-PLV compared to the PLV group, 1/118 (0.9%; odds ratio, 3.00; 95% confidence interval, 0.31-28.84, P= .34).

CONCLUSIONS

In this prospective observational study, we found no differences in the incidence of pneumonia and/or ARDS between patients undergoing lung resection with tidal volumes <8 or ≥8 mL/kg. Our data suggest that when fluid restriction and peak airway pressures are limited, the clinical impact of PLV in this patient population is small. Future randomized trials are needed to better understand the benefits of a small tidal volume strategy during OLV on clinically important outcomes.

Lung-Protective Ventilation Strategies for Relief from Ventilator-Associated Lung Injury in Patients Undergoing Craniotomy: A Bicenter Randomized, Parallel, and Controlled Trial

Current evidence indicates that conventional mechanical ventilation often leads to lung inflammatory response and oxidative stress, while lung-protective ventilation (LPV) minimizes the risk of ventilator-associated lung injury (VALI). This study evaluated the effects of LPV on relief of pulmonary injury, inflammatory response, and oxidative stress among patients undergoing craniotomy. Sixty patients undergoing craniotomy received either conventional mechanical (12 mL/kg tidal volume [V_T] and 0 cm H₂O positive end-expiratory pressure [PEEP]; CV group) or protective lung (6 mL/kg V_T and 10 cm H₂O PEEP; PV group) ventilation. Hemodynamic variables, lung function indexes, and inflammatory and oxidative stress markers were assessed. The PV group exhibited greater dynamic lung compliance and lower respiratory index than the CV group during surgery (P < 0.05). The PV group exhibited higher plasma interleukin- (IL-) 10 levels and lower plasma malondialdehyde and nitric oxide and bronchoalveolar lavage fluid, IL-6, IL-8, tumor necrosis factor-α, IL-10, malondialdehyde, nitric oxide, and superoxide dismutase levels (P < 0.05) than the CV group. There were no significant differences in hemodynamic variables, blood loss, liquid input, urine output, or duration of mechanical ventilation between the two groups (P > 0.05). Patients receiving LPV during craniotomy exhibited low perioperative inflammatory response, oxidative stress, and VALI.