Lung-protective Ventilation Strategies Research Articles

Protective Lung Ventilation Strategy Combined with Prone Position in the Treatment of Severe Pulmonary Aspiration Syndrome: An Experimental Study

Protective Lung Ventilation Strategy Combined with Prone Position in the Treatment of Severe Pulmonary Aspiration Syndrome: An Experimental Study

Pressure-regulated volume control mode versus synchronized intermittent mandatory ventilation mode in management of acute respiratory failure complicating advanced liver disease

Background A common cause of death in the ICUs is advanced liver disease and its complications. Respiratory complications are common in patients with advanced liver disease. Management of patients with advanced hepatic disease having acute respiratory failure mandates the use of lung-protective ventilation strategies to achieve adequate oxygenation. Objectives The aim of this study was to compare and evaluate the superiority of either pressure-regulated volume control (PRVC) mode versus synchronized intermittent mandatory ventilation (SIMV) mode in management of acute respiratory failure complicating advanced hepatic disease. Patients and methods A total of 80 patients were included in this study, who were randomized into two equal groups of 40 patients each, namely. group S and group PV. Group S was ventilated using SIMV mode, whereas group PV was ventilated using PRVC mode. Results There was a statistically significant difference between group PV and group S during the mechanical ventilation period regarding the PO2/FiO2 ratio, static compliance, and dynamic compliance values, with higher values in group PV than group S providing better oxygenation. There was a statistically significant difference in the duration of mechanical ventilation and the ICU stay between the two groups, with significantly lower values in the PV group than the S group. Conclusion We concluded that PRVC mode of mechanical ventilation is superior to SIMV in acute respiratory failure complicating advanced liver disease, as it resulted in improved oxygenation at lower inflation pressures.

High positive pressure at end expiration and recruitment maneuvers—is there a place for this therapy in acute respiratory distress syndrome?

The use of mechanical ventilation (MV) in patients with acute respiratory distress syndrome (ARDS) can exacerbate lung injury, which is usually referred to as ventilator-induced lung injury (VILI). The two most important mechanisms involved in VILI are the excessive volume or pressure that occurs at the end of inspiration, and the repetitive opening and closing of the alveoli. Therefore, lung protective ventilation strategy is based on the use of low tidal volumes and the prevention of intratidal collapse of pulmonary units by providing an appropriate level of positive pressure at end expiration (PEEP). In turn, some authors propose the use of recruitment maneuvers prior to the titration of the PEEP level (1,2) through the conception of open the lung and keep it open (3).

Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model.

BackgroundPositive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury.ObjectivesTo evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation.Methods5–12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers.ResultsAlteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation.ConclusionsSigns of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency of recruitment maneuvers to help ameloriate ventilator-induced lung injury.

The strategy of pulmonary protective ventilation after cardiac arrest resuscitation in critical ill children and the follow-up study

Objective To investigate the strategy of cardiopulmonary resuscitation (CPR) after lung protective mechanical ventilation in critical children and follow-up study of the survivals 90 d after discharge. Methods Four hundred and eighty-nine cases of respiratory cardiac arrest which occurred for various reasons from January 2011 to June 2016 were analyzed in Pediatric Intensive Care Unit (PICU) in Guiyang Children′s Hospital, in which mechanical ventilation was performed after CPR in 251 cases, death, or giving up treatment within 24 h in 83 cases, children surviving > 24 h in 168 cases, 118 cases were assigned into small tidal volume ventilation group, and 50 cases into conventional tidal volume ventilation group, and according to the tidal volume to adjust positive end expiratory pressure ventilation (PEEP), and the oxygen partial pressure [pa(O2)] and the oxygen index (OI), the change of the indexes of blood gas analysis, lactic acid clearance, and oxygenation were also observed. To observe the complications of mechanical ventilation, the situation of withdrawing machine as well as the outcome of the children.Follow-up was conducted for 90 d, including continuous respiratory symptoms, lung imaging examination after discharge and lung function, nervous system examination. Results (1)After mechanical ventilation treatment of 48 hours, compared with the levels of fractional inspired oxygen (FiO2) (0.42±0.15 vs.0.43±0.22), pa(O2)(8.25±0.22 vs.8.27±0.68), OI (5.33±2.01 vs.6.59±1.99) and lactic acid clearance(61.05±1.87 vs.60.93±2.71)between the routine tidal volume ventilation group and the lower tidal volume ventilation group, showing that the difference had no statistical significance (t=1.645, 1.165, 2.302, 2.037, all P>0.05). (2) In small tidal volume group, the incidence of ventilator associated lung injury was significantly lower than that in the conventional tidal volume group, and the difference was statistically significant (χ2=5.873, P 0.05). (4) One hundred and twenty-seven cases of children survived and were discharged, and compared with their discharge, the follow-up of 62 cases after discharge for 30 d, 90 d showed that all the children′s lung function improved, tidal volume, inspiratory and expiratory time ratio(I/E), volume ratio of peak(VP/VE), time ratio of peak(TP/TE) and breathing rate(RR) were also improved, and there was significant difference (F=43.225, 6.108, 68.821, 78.237, 20.361, all P<0.05). (5) Neurological examination and children′s brain function classification rating scale showed that some children had nerve dysfunction. Conclusions Small tidal volume ventilation in reducing the occurrence of ventilator associated lung injury is superior to the conventional tidal volume ventilation. To improve case fatality rate of the children with cardiac arrest resuscitation and oxygenation is not better than the conventional tidal volume group. Dynamic monitoring is helpful to adjust breathing mechanics indexes and parameters and ventilator. Through the follow-up most of the discharged children recovered well, but a few had recurrent respiratory infection and neurological sequelae. Key words: Cardiopulmonary; Lung protective ventilation strategy; Follow-up; Critical ill; Child

Simulation Training for Residents Focused on Mechanical Ventilation

Advances in knowledge regarding mechanical ventilation (MV), in particular lung-protective ventilation strategies, have been shown to reduce mortality. However, the translation of these advances in knowledge into better therapeutic performance in real-life clinical settings continues to lag. High-fidelity simulation with a mannequin allows students to interact in lifelike situations; this may be a valuable addition to traditional didactic teaching. The purpose of this study is to compare computer-based and mannequin-based approaches for training residents on MV. This prospective randomized single-blind trial involved 50 residents. All participants attended the same didactic lecture on respiratory pathophysiology and were subsequently randomized into two groups: the mannequin group (n = 25) and the computer screen-based simulator group (n = 25). One week later, each underwent a training assessment using five different scenarios of acute respiratory failure of different etiologies. Later, both groups underwent further testing of patient management, using in situ high-fidelity simulation of a patient with acute respiratory distress syndrome. Baseline knowledge was not significantly different between the two groups (P = 0.72). Regarding the training assessment, no significant differences were detected between the groups. In the final assessment, the scores of only the mannequin group significantly improved between the training and final session in terms of either global rating score [3.0 (2.5-4.0) vs. 2.0 (2.0-3.0), P = 0.005] or percentage of key score (82% vs. 71%, P = 0.001). Mannequin-based simulation has the potential to improve skills in managing MV.

Dabigatran: A Novel and Rare Cause of Diffuse Alveolar Hemorrhage (DAH)

SESSION TITLE: Diffuse Lung Disease SESSION TYPE: Affiliate Case Report Slide PRESENTED ON: Sunday, October 29, 2017 at 10:45 AM - 12:00 PM INTRODUCTION: DAH is a rare, life-threatening pathology characterized by intra-alveolar hemorrhage with a spectrum of clinical presentations. This syndrome includes hemoptysis, anemia, pulmonary infiltrates and hypoxemic respiratory failure. This case is a rare presentation of DAH secondary to a Novel Oral Anticoagulant (NOAC) in the absence of systemic vasculitis. CASE PRESENTATION: An 86 year old male with past medical history of atrial fibrillation on dabigatran and congestive heart failure, was found at home, hypoxemic and bradycardic to the emergency room. The patient was also noted to be anemic, requiring 2 units of PRBC and in acute renal failure. The patient met criteria for ARDS, including a chest X-ray suggestive of bilateral diffuse pulmonary infiltrates. He was maintained on low tidal volume, high PEEP ventilator support. Bronchoscopic lavage demonstrated progressively more hemorrhagic effluent, pathognomic for DAH. Investigations for vasculitis were negative. The thrombin time was noted to be elevated and hence Idaricizumab was started and hemodialysis initiated. The patient was successfully extubated in 7 days duration. DISCUSSION: GI bleeds and intracranial hemorrhages are known complications with dabigatran, however DAH is rare with only four other cases reported in our literature review1,2. Most of these cases were prior to the advent of Idarucizumab. Dabigatran toxicity may have occurred in this patient due to the occurrence of acute renal failure. Reversal agent may have a role in treating pulmonary hemorrhage and subsequent respiratory failure secondary to the use of NOACs. Interestingly, this patient also had no prior history of vasculitides or lung disease that would predispose the patient to DAH. CONCLUSIONS: To our knowledge this is the only case where resolution of ARDS secondary to DAH by Dabigatran use was achieved with the use of Idarucizumab, hemodialysis and lung protective ventilator strategy. This highlights the importance of considering DAH as a cause of ARDS especially in the setting of anticoagulation. Increasing use of NOACs requires physicians to be aware of the adverse effects and indications for using reversal agents, when available. Reference #1: Yokoi K, Isoda K, Kimura T, Adachi T. Diffuse Alveolar Hemorrhage Associated with Dabigatran. Intern Med. 2012;51(18):2667-2668 Reference #2: Kudo, K, Tanimoto, Y, Hisamoto, A, Ichihara, E, Tanimoto, M, Kiura, K. Dabigatran etexilate-induced alveolar hemorrhage. AJRS, 1(3): 247-250, 2012. DISCLOSURE: The following authors have nothing to disclose: Shyam Shankar, Prarthna Chandar, Hatem Desoky, Ishan Malhotra, Anand Kumar Rai, Mangalore Amith Shenoy, Benhoor Shamian, Pavel Gozenput, Roman Bernstein, Pavan Irukulla, Yizhak Kupfer No Product/Research Disclosure Information

Effects of intraoperative PEEP optimization on postoperative pulmonary complications and the inflammatory response: study protocol for a randomized controlled trial

BackgroundPatients undergoing general anesthesia and mechanical ventilation during major abdominal surgery commonly develop pulmonary atelectasis and/or hyperdistention of the lungs. Recent studies show benefits of lung-protective mechanical ventilation with the use of low tidal volumes, a moderate level of positive end-expiratory pressure (PEEP) and regular alveolar recruitment maneuvers during general anesthesia, even in patients with healthy lungs. The purpose of this clinical trial is to evaluate the effects of intraoperative lung-protective mechanical ventilation, using individualized PEEP values, on postoperative pulmonary complications and the inflammatory response.Methods/designA total number of 40 patients with bladder cancer undergoing open radical cystectomy and urinary diversion (ileal conduit or orthotopic bladder substitute) will be enrolled and randomized into a study (SG) and a control group (CG). Standard lung-protective ventilation with a PEEP of 6 cmH2O will be applied in the CG and an optimal PEEP value determined during a static pulmonary compliance (Cstat)-directed PEEP titration procedure will be used in the SG. Low tidal volumes (6 mL/Kg ideal bodyweight) and a fraction of inspired oxygen of 0.5 will be applied in both groups. After surgery both groups will receive standard postoperative management. Primary endpoints are postoperative pulmonary complications and serum procalcitonin kinetics during and after surgery until the third postoperative day. Secondary and tertiary endpoints will be: organ dysfunction as monitored by the Sequential Organ Failure Assessment Score, in-hospital stay, 28-day and in-hospital mortality.DiscussionThis trial will assess the possible benefits or disadvantages of an individualized lung-protective mechanical ventilation strategy during open radical cystectomy and urinary diversion regarding postoperative pulmonary complications and the inflammatory response.Trial registrationClinicalTrials.gov, ID: NCT02931409. Registered on 5 October 2016.

Integrated Stress Response Mediates Epithelial Injury in Mechanical Ventilation.

Ventilator-induced lung injury (VILI) is a severe complication of mechanical ventilation that can lead to acute respiratory distress syndrome. VILI is characterized by damage to the epithelial barrier with subsequent pulmonary edema and profound hypoxia. Available lung-protective ventilator strategies offer only a modest benefit in preventing VILI because they cannot impede alveolar overdistension and concomitant epithelial barrier dysfunction in the inflamed lung regions. There are currently no effective biochemical therapies to mitigate injury to the alveolar epithelium. We hypothesize that alveolar stretch activates the integrated stress response (ISR) pathway and that the chemical inhibition of this pathway mitigates alveolar barrier disruption during stretch and mechanical ventilation. Using our established rat primary type I-like alveolar epithelial cell monolayer stretch model and in vivo rat mechanical ventilation that mimics the alveolar overdistension seen in acute respiratory distress syndrome, we studied epithelial responses to mechanical stress. Our studies revealed that the ISR signaling pathway is a key modulator of epithelial permeability. We show that prolonged epithelial stretch and injurious mechanical ventilation activate the ISR, leading to increased alveolar permeability, cell death, and proinflammatory signaling. Chemical inhibition of protein kinase RNA-like endoplasmic reticulum kinase, an upstream regulator of the pathway, resulted in decreased injury signaling and improved barrier function after prolonged cyclic stretch and injurious mechanical ventilation. Our results provide new evidence that therapeutic targeting of the ISR can mitigate VILI.

Etiology and Outcomes of ARDS in a Resource Limited Urban Tropical Setting

BackgroundSeveral studies have been published in the western literature on the incidence, clinical course and outcome of patients with ARDS. However, there is limited data about ARDS in the tropics and moreover, the etiology and outcomes of ARDS in tropical countries are different from those of western nations. In tropical countries like India, resources are limited and costs of therapy play a major role in deciding treatment options. This prospective observational study was designed to analyze the clinical profile, outcomes and predictors of mortality of patients with ARDS in an urban tropical setting. Methods75 patients ≥13 years, admitted in the medical intensive care unit of a teaching hospital in Kerala, India between March 2013 and February 2014, satisfying Berlin definition for ARDS were enrolled in the study. Lung protective ventilation strategy as laid by ARDS Network protocol was followed for every patient on mechanical ventilation. Due to scarcity of ventilators in our institution, invasive ventilation could not be provided for all ARDS patients. The criteria used for patient selection for non-invasive ventilation were hemodynamic stability, well compliant to the use of NIV mask and PaO2/FiO2 ratio >180 at the time of admission. ResultsOut of the 75 patients, 51% were females and the mean age of the study population was 39.8 ± 3.3 years. Common aetiologies were leptospirosis (18.7%), bronchopneumonia (17.3%), scrub typhus and dengue (12% each). Lung injury score and sequential organ failure assessment score scores had statistically significant association with the severity of ARDS. Forty patients (53.3%) received invasive mechanical ventilation and 35 patients were managed with non-invasive ventilation at the time of admission. The mortality in our study was 45%. Altered sensorium (p-0.002), central cyanosis (p-0.024), elevated creatinine (p-0.036), acidosis (p < 0.001), hypotension (p < 0.001), multiorgan dysfunction (p-0.017), PEEP >12 cm H2O (p-0.036), days on ventilator <7 (p-0.014), PaO2/FiO2 Ratio <100 (p < 0.001), LIS>2.5 (p < 0.001) and SOFA score>11 (p < 0.001) were individual predictors of mortality. ConclusionTropical infections form a major etiological component of ARDS in a developing country like India. More studies are required for determining criteria for using NIV in mild ARDS patients which would be helpful in resource limited countries. Timely administration of effective antimicrobial therapy in patients in the rural tropics may help to reduce mortality and financial burden due to ARDS.

New progress of lung protective ventilation strategies during general anesthesia

Background Mechanical ventilation provides an effective means to assist breathing and gas exchange during general anesthesia. It is noteworthy that mechanical ventilation sometimes could induce or exacerbate lung injury (ventilation induced-lung injury, VILI). Increasing number of investigations were conducted to advance our understanding of the causes of VILI, and revealed that protective lung ventilation might reduce the severity of VILI. Objective To review new progress of lung protective ventilation strategies during general anesthesia. Content This article reviews some theories and pros and cons about lung protective ventilation strategies, low tidal volume; proper positive end expiratory pressure (PEEP), recruiting maneuvers (RM), control of plateau pressure and FiO2. Trend Although integrated research of various lung protective ventilation strategies have achieved remarkable progress, individualized lung protective strategies need further investigations to improve the quality of anesthesia. Key words: Anesthesia, general; Mechanical ventilation; Lung injury; Lung protective strategy

Linking Ventilator Injury-Induced Leak across the Blood-Gas Barrier to Derangements in Murine Lung Function.

Mechanical ventilation is vital to the management of acute respiratory distress syndrome, but it frequently leads to ventilator-induced lung injury (VILI). Understanding the pathophysiological processes involved in the development of VILI is an essential prerequisite for improving lung-protective ventilation strategies. The goal of this study was to relate the amount and nature of material accumulated in the airspaces to biomarkers of injury and the derecruitment behavior of the lung in VILI. Forty-nine BALB/c mice were mechanically ventilated with combinations of tidal volume and end-expiratory pressures to produce varying degrees of overdistension and atelectasis while lung function was periodically assessed. Total protein, serum protein, and E-Cadherin levels were measured in bronchoalveolar lavage fluid (BALF). Tissue injury was assessed by histological scoring. We found that both high tidal volume and zero positive end-expiratory pressure were necessary to produce significant VILI. Increased BALF protein content was correlated with increased lung derecruitability, elevated peak pressures, and histological evidence of tissue injury. Blood derived molecules were present in the BALF in proportion to histological injury scores and epithelial injury, reflected by E-Cadherin levels in BALF. We conclude that repetitive recruitment is an important factor in the pathogenesis of VILI that exacerbates injury associated with tidal overdistension. Furthermore, the dynamic mechanical behavior of the injured lung provides a means to assess both the degree of tissue injury and the nature and amount of blood-derived fluid and proteins that accumulate in the airspaces.

Effect of protective lung ventilation strategy combined with lung recruitment maneuver in patients with acute respiratory distress syndrome (ARDS)

Objective: To evaluate the efficacy and safety of protective lung ventilation strategy combined with lung recruitment maneuver (RM) in the treatment patients with acute respiratory distress syndrome (ARDS). Methods: Totally 74 patients with ARDS admitted to the Department of Intensive Care Unit, Changshu Second People's Hospital in Jiangsu Province between September 2010 and June 2013 were selected and randomly divided into lung recruitment group and non-lung recruitment group, and the initial ventilation solution for both groups was synchronized intermittent mandatory ventilation (SIMV). For RM, SIMV mode (pressure control and pressure support) was adopted. Positive end expiratory pressure (PEEP) was increased by 5 cm H2O every time and maintained for 40-50 s before entering the next increasing period, and the peak airway pressure was kept below 45 cm H2O. After PEEP reached the maximum value, it was gradually reduced by 5 cm H2O every time and finally maintained at 15 cm H2O for 10 min. Results: A total of 74 patients with mean age of (49.0±18.6) years old were enrolled, 36 patients were enrolled in lung recruitment maneuver (RM) group and 38 patients were enrolled into non-lung recruitment maneuver (non-RM) group. 44 were male and accounted for 59.5% of all the patients. For the indicators such as PEEP, pressure support (PS), plateau airway pressure (Pplat), peak airway pressure (Ppeak), vital capacity (VC) and fraction of inspired oxygen (FiO2), no statistical differences in the indicators were found between the RM group and non-RM group on D1, D3 and D7 (P>0.05), except that only FiO2 of RM group on D7 was significantly lower than that of non-RM group (47.2±10.0) vs. (52.2±10.5), P 0.05). 28-day mortality, ICU mortality and in-hospital mortality were 25% vs. 28.9%, 25% vs. 26.3% and 36.1% vs. 39.5% respectively between RM group and non-RM group (all P>0.05). Conclusion: Protective lung ventilation strategy combined with lung recruitment maneuver can improve the indicators such as PaO2, FiO2 and PaO2/FiO2 on D7, but failed to improve the final outcomes such as 28-day mortality, ICU mortality and in-hospital mortality.

Tidal volume in acute respiratory distress syndrome: how best to select it.

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

Effects of staff training and electronic event monitoring on long-term adherence to lung-protective ventilation recommendations

PurposeTo investigate long-term effects of staff training and electronic clinical decision support (CDS) on adherence to lung-protective ventilation recommendations. Materials and methodsIn 2012, group instructions and workshops at two surgical intensive care units (ICUs) started, focusing on standardized protocols for mechanical ventilation and volutrauma prevention. Subsequently implemented CDS functions continuously monitor ventilation parameters, and from 2015 triggered graphical notifications when tidal volume (VT) violated individual thresholds. To estimate the effects of these educational and technical interventions, we retrospectively analyzed nine years of VT records from routine care. As outcome measures, we calculated relative frequencies of settings that conform to recommendations, case-specific mean excess VT, and total ICU survival. ResultsAssessing 571,478 VT records from 10,241 ICU cases indicated that adherence during pressure-controlled ventilation improved significantly after both interventions; the share of conforming VT records increased from 61.6% to 83.0% and then 86.0%. Despite increasing case severity, ICU survival remained nearly constant over time. ConclusionsStaff training effectively improves adherence to lung-protective ventilation strategies. The observed CDS effect seemed less pronounced, although it can easily be adapted to new recommendations. Both interventions, which futures studies could deploy in combination, promise to improve the precision of mechanical ventilation.

The application of lung protective ventilation strategy in laparoscopic surgery of obese patients

With the ventilator associated lung injury(VALI) atracting more and more attention, lung protective ventilation strategy (LPVS) has gradually been applied to clinical practice. Obese patients are at higher risk in VALI for laparoscopic surgery, mechanical ventilation induced atelectasis is an important reason for low oxygen in intraoperative and postoperativen procedure. In laparoscopic surgery, high abdominal pressure causes the elevation of diaphragm, and increases airway pressure. The excessive pressure increases the amount of alveolar dead space and airway pressure, reduces lung compliance, and increases the possibility of barotrauma and colotrauma. In addition, carbon dioxide pnenmoperitoneum indces hypercapnia. Both of them influence the recovery of postoperative lung function. To optimize intraoperative management and improve the prognosis of patients with general anesthesia, the application of LPVS attracts more attention, including small tidal volume, positive end-expiratory pressure, and recruitment maneuvers, etc. However, LVPS may also cause lung injury. This article is a review on the application of LPVS in laparoscopic surgery of obese patients. Key words: Pulmonary ventilation; Obesity/SU; Laparoscopy; Review

Effects of an alveolar recruitment maneuver on subdural pressure, brain swelling, and mean arterial pressure in patients undergoing supratentorial tumour resection: a randomized crossover study

Although recruitment maneuvers have been advocated as part of a lung protective ventilation strategy, their effects on cerebral physiology during elective neurosurgery are unknown. Our objectives were to determine the effects of an alveolar recruitment maneuver on subdural pressure (SDP), brain relaxation score (BRS), and cerebral perfusion pressure among patients undergoing supratentorial tumour resection. In this prospective crossover study, patients scheduled for resection of a supratentorial brain tumour were randomized to undergo either a recruitment maneuver (30 cm of water for 30 sec) or a "sham" maneuver (5 cm of water for 30 sec), followed by the alternative intervention after a 90-sec equilibration period. Subdural pressure was measured through a dural perforation following opening of the cranium. Subdural pressure and mean arterial pressure (MAP) were recorded continuously. The blinded neurosurgeon provided a BRS at baseline and at the end of each intervention. During each treatment, the changes in SDP, BRS, and MAP were compared. Twenty-one patients underwent the study procedure. The increase in SDP was higher during the recruitment maneuver than during the sham maneuver (difference, 3.9 mmHg; 95% confidence interval [CI], 2.2 to 5.6; P < 0.001). Mean arterial pressure decreased further in the recruitment maneuver than in the sham maneuver (difference, -9.0 mmHg; 95% CI, -12.5 to -5.6; P < 0.001). Cerebral perfusion pressure decreased 14 mmHg (95% CI, 4 to 24) during the recruitment maneuver. The BRS did not change with either maneuver. Our results suggest that recruitment maneuvers increase subdural pressure and reduce cerebral perfusion pressure, although the clinical importance of these findings is thus far unknown. This trial was registered with ClinicalTrials.gov, NCT02093117.

Effect of lung protective ventilation strategies on improving postoperative pulmonary complications in patients with high risk factors

Background Pulmonary complications are major cause of postoperative mortality. Many factors aggravate pulmonary complications(PPC). Lung protective ventilation strategy prevents pulmonary complications to some extent. Objective To know if lung protective ventilation strategies can improve clinical outcomes of patients with high risk factors. Content To explain if lung protective ventilation strategies can improve clinical outcomes of patients with high risk factors like smoking, advanced age, pulmonary hypertension, chronic obstructive pulmonary disease(COPD), cardiac and neurologic diseases, and so on. Trend In patients with acute respiratory distress syndrome(ARDS), ventilation with low tidal volumes and high level of positive end expiratory pressure(PEEP) are recommended, and intraoperative ventilation should continue the settings applied on the ICU. In other critically ill patients, the evidence for the benefits of low tidal volume ventilation is growing. Low tidal volumes could cause excessive hypercapnia. High level of PEEP could cause dynamic hyperinflation, increased intracranial pressure and increased incidence of hemodynamic instability. We should not use lung protective ventilation strategies blindly. In patients with comorbidities, further research is necessary to find out whether lung protective ventilation should be adopted. Key words: Lung protective ventilation strategies; Postoperative pulmonary complications

Low flow veno-venous extracorporeal CO2 removal for acute hypercapnic respiratory failure.

Ventilation with low tidal volume and airway pressure results in a survival benefit in ARDS patients. Previous research suggests that avoiding mechanical ventilation altogether may be beneficial in some cases of respiratory failure. Our hypothesis was that low flow veno-venous extracorporeal CO2 removal (ECCO2R) enables maintenance of a lung protective ventilation strategy or awake spontaneous ventilation despite severe hypercapnic respiratory failure (HRF). Twenty patients with HRF were investigated while mechanically ventilated (N.=14) or breathing spontaneously close to respiratory exhaustion (N.=6). Low flow ECCO2R was performed using a hemoperfusion device with a polypropylene gas-exchanger. Causes of HRF were severe ARDS (N.=11), COPD (N.=4), chronic lung transplant rejection (N.=3) and cystic fibrosis (N.=2). During the first 8h of ECCO2R, PaCO2 decreased from 10.6 (9.3-12.9) to 7.9 (7.3-9.3) kPa (P<0.001) and pH increased from 7.23 (7.09-7.40) to 7.36 (7.27-7.41) (P<0.05). Thereafter, steady state was achieved while maintaining lung protective tidal volume (4.7 (3.8-6.5) mL/kg) and peak ventilator pressure (28 (27-30) mbar at 24 h). During the first 48 h, thrombocyte count decreased by 52% (P<0.01), Fibrinogen by 38% (P<0.05). Intubation could be avoided in all spontaneously breathing patients. In 4/6 high blood flow extracorporeal circulation was required due to increased oxygen demand. 6/14 mechanically ventilated patients recovered from respiratory support. Our results suggest that in mechanically ventilated patients with HRF, low flow ECCO2R supports the maintenance of lung protective tidal volume and peak ventilator pressure. In selected awake patients with acute HRF, it may be a novel treatment approach to avoid mechanical ventilation, hence preventing ventilator- and sedation-associated morbidity and mortality.

The clinical application of tracheal gas insufflation

Tracheal gas insufflation is a non conventional respiratory support technology.It might avoid severe CO2 retention in lung protective ventilation strategy, reduce ventilator-associated lung injury, which was recommented recently.In this article, we made a brief introduction of the principle, classification and clinical applications of tracheal gas insufflation technique. Key words: Tracheal gas insufflation; Mechanical ventilation; Lung protective ventilation strategy,