Pathogenesis of ventilator-induced lung injury: trials and tribulations

The relationship of tidal volume and driving pressure with mortality in hypoxic patients receiving mechanical ventilation

PURPOSE

To determine whether tidal volume/predicted body weight (TV/PBW) or driving pressure (DP) are associated with mortality in a heterogeneous population of hypoxic mechanically ventilated patients.

METHODS

A retrospective cohort study involving 18 intensive care units included consecutive patients ≥18 years old, receiving mechanical ventilation for ≥3 days, with a PaO2/FiO2 ratio ≤300 mmHg, whether or not they met full criteria for ARDS. The main outcome was hospital mortality. Multiple logistic regression (MLR) incorporated TV/PBW, DP, and potential confounders including age, APACHE IVa® predicted hospital mortality, respiratory system compliance (CRS), and PaO2/FiO2. Predetermined strata of TV/PBW were compared using MLR.

RESULTS

Our cohort comprised 5,167 patients with mean age 61.9 years, APACHE IVa® score 79.3, PaO2/FiO2 166 mmHg and CRS 40.5 ml/cm H2O. Regression analysis revealed that patients receiving DP one standard deviation above the mean or higher (≥19 cmH20) had an adjusted odds ratio for mortality (ORmort) = 1.10 (95% CI: 1.06-1.13, p = 0.009). Regression analysis showed a U-shaped relationship between strata of TV/PBW and adjusted mortality. Using TV/PBW 4-6 ml/kg as the referent group, patients receiving >10 ml/kg had similar adjusted ORmort, but those receiving 6-7, 7-8 and 8-10 ml/kg had lower adjusted ORmort (95%CI) of 0.81 (0.65-1.00), 0.78 (0.63-0.97) and 0.80 0.67-1.01) respectively. The adjusted ORmort in patients receiving 4-6 ml/kg was 1.26 (95%CI: 1.04-1.52) compared to patients receiving 6-10 ml/kg.

CONCLUSIONS

Driving pressures ≥19 cmH2O were associated with increased adjusted mortality. TV/PBW 4-6ml/kg were used in less than 15% of patients and associated with increased adjusted mortality compared to TV/PBW 6-10 ml/kg used in 82% of patients. Prospective clinical trials are needed to prove whether limiting DP or the use of TV/PBW 6-10 ml/kg versus 4-6 ml/kg benefits mortality.

Comprehensive Pulmonary Rehabilitation is an Effective Way for Better Postoperative Outcomes in Surgical Lung Cancer Patients with Risk Factors: A Propensity Score-Matched Retrospective Cohort Study

Background

To investigate the effectiveness and cost minimization of comprehensive pulmonary rehabilitation (CPR) in lung cancer patients who underwent surgery.

Patients and Methods

A retrospective observational study based on medical records was conducted, with 2410 lung cancer patients who underwent an operation with/without CPR during the peri-operative period. Variables including clinical characteristics, length of stay (LOS), postoperative pulmonary complications (PPCs), and hospitalization expenses were compared between the intervention group (IG) and control group (CG). The CPR regimen consists of inspiratory muscle training (IMT), aerobic endurance training, and pharmacotherapy.

Results

Propensity score matching analysis was performed between two groups, and the ratio of matched patients was 1:4. Finally, 205 cases of IG and 820 cases of CG in the matched cohort of our study were identified. The length of postoperative hospital stay [median: 5 interquartile (4–7) vs 7 (4–8) days, P < 0.001] and drug expenses [7146 (5411–8987) vs 8253 (6048–11,483) ¥, P < 0.001] in the IG were lower compared with the CG. Additionally, the overall incidence of PPCs in the IG was reduced compared with the CG (26.8% vs 36.7%, P = 0.008), including pneumonia (10.7% vs 16.8%, P = 0.035) and atelectasis (8.8% vs 14.0%, P = 0.046). Multivariable analysis showed that CPR intervention (OR = 0.655, 95% CI: 0.430–0.865, P = 0.006), age ≥70 yr (OR = 1.919, 95% CI: 1.342–2.744, P < 0.001), smoking (OR = 2.048, 95% CI: 1.552–2.704, P < 0.001) and COPD (OR = 1.158, 95% CI: 1.160–2.152, P = 0.004) were related to PPCs.

Conclusion

The retrospective cohort study revealed a lower PPC rate and the shorter postoperative length of stay in the patients receiving CPR, demonstrating the clinical value of CRP as an effective strategy for surgical lung cancer patients with risk factors.

Effects of lung protective ventilation on postoperative pulmonary outcomes for prolonged oral cancer combined with free flap surgery

The intraoperative lung protective ventilation with low tidal volume, positive end expiratory pressure (PEEP) and intermittent lungs recruitment was found to decrease postoperative pulmonary complications. In this retrospective medical records study, we investigated the effects of lung protective ventilation on postoperative pulmonary outcomes among the patients received prolonged oral cancer combined with free flap surgery.We collected the medical records of the patients received oral cancer surgery with the operation time more than 12 hours from January 2011 to December 2015. We recordedFifty nine cases were included. Thirty cases received the lung protective ventilation and 29 cases received conventional ventilation. Compared to the patients received conventional ventilation, the patients received intraoperative lung protective ventilation showedIn conclusion, for the prolonged oral cancer combined with free flap surgery, the intraoperative lung protective ventilation improves postoperative pulmonary outcomes and decreases the duration of ICU stay.

Data on the effects of remote ischemic preconditioning in the lungs after one-lung ventilation

This article contains data on experimental endpoints of a randomized controlled animal trial. Fourteen healthy piglets underwent mechanical ventilation including injurious one-lung ventilation (OLV), seven of them experienced four cycles of remote ischemic preconditioning (RIP) on one hind limb immediately before OLV, seven of them did not receive RIP and served as controls, in a randomized manner. The two major endpoints were (1) pulmonary damage assessed with the diffuse alveolar damage (DAD) score and (2) the inflammatory response assessed by cytokine concentrations in serum and in bronchoalveolar lavage fluids (BAL). The cytokine levels in the homogenized lung tissue samples are presented in the original article. Further interpretation and discussion of these data can be found in Bergmann et al. (in press).

The effect of an intraoperative, lung-protective ventilation strategy in neurosurgical patients undergoing craniotomy: study protocol for a randomized controlled trial

BACKGROUND

Ventilator-induced lung injury is a major cause of postoperative pulmonary complications (PPCs) in patients undergoing neurosurgery after general anesthesia. However, there is no study on the effect of a lung-protective ventilation strategy in patients undergoing neurosurgery.

METHODS

This is a single-center, randomized, parallel-group controlled trial which will be carried out at Beijing Tiantan Hospital, Capital Medical University. Three hundred and thirty-four patients undergoing intracranial tumor surgery will be randomly allocated to the control group and the protective-ventilation strategy group. In the control group, tidal volume (VT) will be set at 10-12 ml/kg of predicted body weight but PEEP and recruitment maneuvers will not be used. In the protective group, VT will be set at 6-8 ml/kg of predicted body weight, PEEP at 6-8 cmH₂O, and a recruitment maneuver will be used intermittently. The primary outcome is pulmonary complications within 7 days postoperatively. Secondary outcomes include intraoperative brain relaxation, the postoperative complications within 30 days and the cost analysis.

DISCUSSION

This study aims to determine if the protective, pulmonary-ventilation strategy decreases the incidence of PPCs in patients undergoing neurosurgical anesthesia. If our results are positive, the study will indicate whether the protective, pulmonary-ventilation strategy is efficiently and safely used in neurosurgical patients undergoing the craniotomy.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02386683 . Registered on 18 October 2014.

Doxapram Dosing for Apnea of Prematurity Based on Postmenstrual Age and Gender: A Randomized Controlled Trial

INTRODUCTION

Doxapram is used as a third-line treatment for apnea unresponsive to caffeine and continuous positive airway pressure (CPAP) in preterm infants.

OBJECTIVES

The objectives of this study were to compare the effects of dosing adjusted for gender and postmenstrual age (PMA) (GrA) versus infants' weight alone (GrW) on doxapram plasma levels, clinical efficacy, and side effects.

METHODS

This was a randomized, double-blind study, including premature infants for whom optimized caffeine and CPAP therapy for apnea of prematurity had failed. Failure was defined as the persistence of more than one significant apnea per hour over an 8-h period. Plasma levels of doxapram and ketodoxapram were measured with high-performance liquid chromatography (HPLC) 48 h after the onset of treatment. Dosing aimed to maintain the combined doxapram and ketodoxapram plasma level in the therapeutic range of 1.5-4 mg/l. Infants were followed-up for 4 days after the onset of treatment.

RESULTS

A total of 85 infants were included: 46 in GrW (27.7 ± 1.9 weeks' gestational age [GA]), 39 in GrA (27.9 ± 1.4 weeks' GA); available plasma levels showed that 25 of 40 in the GrW group and 27 of 37 in the GrA group had levels within the therapeutic range (p = 0.344). Of note, plasma level variance was significantly higher in GrW for doxapram + ketodoxapram (1.87 vs. 0.89; p = 0.028). Clinical efficacy was better in the GrA group, with a reduction from 32 to 3 of 38 (76 %) infants with significant apnea versus 30 to 5 of 45 (56 %) in the GrW group (p < 0.001). No adverse effects were observed during the study.

CONCLUSIONS

Taking gender and PMA into account for doxapram dosing did not significantly increase the number of infants with a plasma level in the therapeutic range. However, it improved plasma level stability and clinical efficacy without adverse effects. ClinicalTrials.gov number: NCT00389909.

Pediatric Acute Respiratory Distress Syndrome: Fibrosis versus Repair

Clinical and basic experimental approaches to pediatric acute lung injury (ALI), including acute respiratory distress syndrome (ARDS), have historically focused on acute care and management of the patient. Additional efforts have focused on the etiology of pediatric ALI and ARDS, clinically defined as diffuse, bilateral diseases of the lung that compromise function leading to severe hypoxemia within 7 days of defined insult. Insults can include ancillary events related to prematurity, can follow trauma and/or transfusion, or can present as sequelae of pulmonary infections and cardiovascular disease and/or injury. Pediatric ALI/ARDS remains one of the leading causes of infant and childhood morbidity and mortality, particularly in the developing world. Though incidence is relatively low, ranging from 2.9 to 9.5 cases/100,000 patients/year, mortality remains high, approaching 35% in some studies. However, this is a significant decrease from the historical mortality rate of over 50%. Several decades of advances in acute management and treatment, as well as better understanding of approaches to ventilation, oxygenation, and surfactant regulation have contributed to improvements in patient recovery. As such, there is a burgeoning interest in the long-term impact of pediatric ALI/ARDS. Chronic pulmonary deficiencies in survivors appear to be caused by inappropriate injury repair, with fibrosis and predisposition to emphysema arising as irreversible secondary events that can severely compromise pulmonary development and function, as well as the overall health of the patient. In this chapter, the long-term effectiveness of current treatments will be examined, as will the potential efficacy of novel, acute, and long-term therapies that support repair and delay or even impede the onset of secondary events, including fibrosis.

Effect of Therapeutic Hypercapnia on Inflammatory Responses to One-lung Ventilation in Lobectomy Patients

BACKGROUND

One-lung ventilation (OLV) can result in local and systemic inflammation. This prospective, randomized trial was to evaluate the effect of therapeutic hypercapnia on lung injury after OLV.

METHOD

Fifty patients aged 20 to 60 yr undergoing lobectomy were randomly provided with air or carbon dioxide (partial pressure of carbon dioxide: 35 to 45 mmHg or 60 to 70 mmHg). Peak pressure, plateau pressure, and lung compliance were recorded. Bronchoalveolar lavage fluid (BALF) and blood samples were collected. Adverse events were monitored. The primary outcome was the concentration of BALF tumor necrosis factor, and the secondary outcomes were serum cytokine concentrations.

RESULTS

The BALF tumor necrosis factor was lower in the carbon dioxide group than in the air group (median [range], 51.1 [42.8 to 76.6] vs. 71.2 [44.8 to 92.7]; P = 0.034). Patients in the carbon dioxide group had lower concentrations of serum and BALF interleukin (IL)-1, IL-6, and IL-8, but higher serum concentrations of IL-10, accompanied by reduced numbers of cells and neutrophils as well as lower concentrations of protein in the BALF. Also, patients in the carbon dioxide group had lower peak (mean ± SD, 22.2 ± 2.9 vs. 29.8 ± 4.6) and plateau pressures (20.5 ± 2.4 vs. 27.1 ± 2.9), but higher dynamic compliance (46.6 ± 5.8 vs. 38.9 ± 6.5). Furthermore, patients in the carbon dioxide group had higher postoperation oxygenation index values. Ten patients experienced slightly increased blood pressure and heart rate during OLV in the carbon dioxide group.

CONCLUSION

Under intravenous anesthesia, therapeutic hypercapnia inhibits local and systematic inflammation and improves respiratory function after OLV in lobectomy patients without severe complications.

Mechanical ventilation-associated lung fibrosis in acute respiratory distress syndrome: a significant contributor to poor outcome

One of the most challenging problems in critical care medicine is the management of patients with the acute respiratory distress syndrome. Increasing evidence from experimental and clinical studies suggests that mechanical ventilation, which is necessary for life support in patients with acute respiratory distress syndrome, can cause lung fibrosis, which may significantly contribute to morbidity and mortality. The role of mechanical stress as an inciting factor for lung fibrosis versus its role in lung homeostasis and the restoration of normal pulmonary parenchymal architecture is poorly understood. In this review, the authors explore recent advances in the field of pulmonary fibrosis in the context of acute respiratory distress syndrome, concentrating on its relevance to the practice of mechanical ventilation, as commonly applied by anesthetists and intensivists. The authors focus the discussion on the thesis that mechanical ventilation-or more specifically, that ventilator-induced lung injury-may be a major contributor to lung fibrosis. The authors critically appraise possible mechanisms underlying the mechanical stress-induced lung fibrosis and highlight potential therapeutic strategies to mitigate this fibrosis.

Long-term home noninvasive mechanical ventilation increases systemic inflammatory response in chronic obstructive pulmonary disease: a prospective observational study

Background. Long-term home noninvasive mechanical ventilation (NIV) is beneficial in COPD but its impact on inflammation is unknown. We assessed the hypothesis that NIV modulates systemic and pulmonary inflammatory biomarkers in stable COPD. Methods. Among 610 patients referred for NIV, we shortlisted those undergoing NIV versus oxygen therapy alone, excluding subjects with comorbidities or non-COPD conditions. Sputum and blood samples were collected after 3 months of clinical stability and analyzed for levels of human neutrophil peptides (HNP), interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNF-alpha). Patients underwent a two-year follow-up. Unadjusted, propensity-matched, and pH-stratified analyses were performed. Results. Ninety-three patients were included (48 NIV, 45 oxygen), with analogous baseline features. Sputum analysis showed similar HNP, IL-6, IL-10, and TNF-alpha levels (P > 0.5). Conversely, NIV group exhibited higher HNP and IL-6 systemic levels (P < 0.001) and lower IL-10 concentrations (P < 0.001). Subjects undergoing NIV had a significant reduction of rehospitalizations during follow-up compared to oxygen group (P = 0.005). These findings were confirmed after propensity matching and pH stratification. Conclusions. These findings challenge prior paradigms based on the assumption that pulmonary inflammation is per se detrimental. NIV beneficial impact on lung mechanics may overcome the potential unfavorable effects of an increased inflammatory state.

Lung protective ventilation in patients undergoing major surgery: a systematic review protocol

INTRODUCTION

There is growing interest in the use of low tidal volume ventilation in patients undergoing general anaesthesia. However, its potential benefit has long been debated and conflicting results have been reported. We describe here the protocol of a systematic review and meta-analysis for investigating the beneficial effects of low tidal volume ventilation in patients undergoing general anaesthesia.

METHODS AND ANALYSIS

Data sources include PubMed, Scopus, Embase and EBSCO. Patients undergoing general anaesthesia will be included irrespective of type of surgery. The intervention is low tidal volume ventilation or protective ventilation, and the control is conventional ventilation. The quality of included trials will be assessed by using Delphi consensus. Outcomes include new onset lung injury, atelectasis, arrhythmia, levels of inflammatory biomarkers, arterial oxygenation, partial pressure of carbon dioxide and alveolar-arterial oxygen gradient. Conventional approaches for meta-analysis will be used, and heterogeneity will be investigated by using subgroup analysis and meta-regression if appropriate. The Bayesian method will be used for the synthesis of binary outcome data.

ETHICS AND DISSEMINATION

The systematic review was approved by the ethics committee of Jinhua hospital of Zhejiang university and will be published in a peer-reviewed journal and will be disseminated electronically and in print.

REGISTRATION DETAILS

The study protocol has been registered in PROSPERO (http://www.crd.york.ac.uk/PROSPERO/) under registration number CRD42013006416.

Lung ventilation strategies and regional lung inflammation

Protective mechanical ventilation is currently accepted as a key strategy for the management of acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome. The study by de Prost and colleagues in the current issue of Critical Care provides new insights into the impact of ventilation strategies on pulmonary function, gas exchange, and regional cellular metabolic activity during early ALI in sheep. The group reports that a protective ventilation strategy may attenuate neutrophil activation in dependent lung regions during early experimental ALI. This is an innovative report that provides the basis for further study.

Lung-derived mediators induce cytokine production in downstream organs via an NF-κB-dependent mechanism

In the setting of acute lung injury, levels of circulating inflammatory mediators have been correlated with adverse outcomes. Previous studies have demonstrated that injured, mechanically ventilated lungs represent the origin of the host inflammatory response; however, mechanisms which perpetuate systemic inflammation remain uncharacterized. We hypothesized that lung-derived mediators generated by mechanical ventilation (MV) are amplified by peripheral organs in a "feed forward" mechanism of systemic inflammation. Herein, lung-derived mediators were collected from 129X1/SVJ mice after 2 hours of MV while connected to the isolated perfused mouse lung model setup. Exposure of liver endothelial cells to lung-derived mediators resulted in a significant increase in G-CSF, IL-6, CXCL-1, CXCL-2, and MCP-1 production compared to noncirculated control perfusate media (P < 0.05). Furthermore, inhibition of the NF-κB pathway significantly mitigated this response. Changes in gene transcription were confirmed using qPCR for IL-6, CXCL-1, and CXCL-2. Additionally, liver tissue obtained from mice subjected to 2 hours of in vivo MV demonstrated significant increases in hepatic gene transcription of IL-6, CXCL-1, and CXCL-2 compared to nonventilated controls. Collectively, this data demonstrates that lung-derived mediators, generated in the setting of MV, are amplified by downstream organs in a feed forward mechanism of systemic inflammation.

Nuclear factor-kappa B mediates one-lung ventilation-induced acute lung injury in rabbits

INTRODUCTION

Several studies have revealed the adverse effect of one-lung ventilation (OLV) on pulmonary function. Nuclear factor-kappa B (NF-κB) is a principal transcription factor of proinflammatory genes. This study was designed to investigate the role of NF-κB in OLV-mediated lung injury.

METHODS

Male rabbits, weighing 2.2 ± 0.3 kg, were randomly divided into five groups: sham tracheostomized (Sham), OLV (V(T) = 10 ml/kg, FiO(2) = 1.0), two-lung ventilation (TLV, V(T) = 10 ml/kg, FiO(2) = 1.0), OLV preceded by the treatment with NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC, 50 mg/kg, i.v.), and TLV with the PDTC pretreatment. Arterial blood gases, lung pathological changes, and production of proinflammatory cytokines (tumor necrosis factor-α and interleukin-8) were assessed. NF-κB activation was determined by electrophoretic mobility shift assay (EMSA) and western blotting of nuclear NF-κB p65.

RESULTS

The OLV significantly decreased the ratio of partial pressure of oxygen and fraction inspired oxygen (PaO(2)/FiO(2)) compared to the Sham group (p < .01). However, the TLV had no evident effect on the PaO(2)/FiO(2) ratio. The pretreatment with PDTC significantly reversed the OLV-induced reduction in the PaO(2)/FiO(2) ratio. The PDTC pretreatment also markedly attenuated the OLV-mediated lung injury and proinflammatory cytokine production. The OLV potentiated the NF-κB DNA binding activity assessed by EMSA and the NF-κB nuclear translocation. The OLV-mediated NF-κB activation was markedly inhibited by the PDTC pretreatment.

CONCLUSION

Our data collectively demonstrate that OLV can cause lung injury through the activation of NF-κB and the production of proinflammatory cytokines. Blocking NF-κB reduces lung inflammation and may be an effective strategy in the management of OLV-induced lung damage.

Early physiological and biological features in three animal models of induced acute lung injury

INTRODUCTION

Critically ill patients often develop acute lung injury (ALI) in the context of different clinical conditions. We aimed to explore differences in early local and systemic features in three experimental animal models of ALI.

METHODS

Mechanically ventilated male Sprague-Dawley rats were randomized to high tidal volume (VT) ventilation (HVT) (n = 8, VT 24 ml/kg), massive brain injury (MBI) (n = 8, VT 8 ml/kg) or endotoxemia (LPS) (n = 8, VT 8 ml/kg). Each experimental group had its own control group of eight rats (VT 8 ml/kg). We measured arterial blood gases, mean arterial pressure, lung compliance, inflammatory mediators in plasma and their expression and gelatinase activity in the lungs after 3 h of injury.

RESULTS

Despite maintaining relatively normal lung function without evidence of important structural changes, we observed altered lung and systemic inflammatory responses in all three experimental models. LPS triggered the most robust inflammatory response and HVT the lowest systemic proinflammatory response. The HVT group had higher Il6, Tnf and Cxcl2 mRNA in lungs than MBI animals. Metalloproteinase activity/expression and neutrophilic recruitment in the lungs were higher in HVT than in LPS or MBI.

CONCLUSIONS

The early responses to direct or remote lung insult in our three models of ALI captured different physiological and biological features that could lead to respiratory and/or multiorgan failure.

Effects of distension on airway inflammation and venular P-selectin expression

We previously have shown in mice and rats, enhanced leukocyte recruitment to airway postcapillary venules after excessive distention imposed by the application of positive end-expiratory pressure. Because P-selectin was shown to be essential for this outcome, we sought to establish an in vitro endothelial cell model and determine the mechanisms whereby mechanical distension alters adhesion molecule expression. P-selectin surface expression on mouse jugular vein endothelial cells exposed to cyclic stretch (5 or 20% elongation for 5 min; Flexercell) were compared with static cells. The larger, pathophysiological regimen of cyclic stretch showed a 54% increase in P-selectin expression after stretch compared with static cells. This response was attenuated but confirmed in tracheal venular endothelium (29% increase). We questioned whether these changes were dependent on increases in intracellular Ca(2+) through voltage-gated Ca(2+) channels. The stretch-induced increase in P-selectin expression was substantially decreased by pretreatment with the T-type Ca(2+) channel inhibitor mibefradil (76% inhibition). Furthermore, when the Ca(v)3.1 T-type Ca(2+) channel expression was decreased in both endothelial cell subtypes with specific small-interfering RNA, the distension-induced expression of P-selectin decreased to levels less than that observed in static cells. We conclude that P-selectin expression on systemic venular endothelial cells contributes to a proinflammatory phenotype after mechanical stretch and can be selectively modulated by voltage-gated calcium channel inhibition.

Improving survival by increasing lung edema clearance: is airspace delivery of dopamine a solution?

In this issue of Critical Care Chamorro-Marin and coworkers provide new evidence that dopamine instilled into airspaces is beneficial in a rat model of ventilator-induced lung injury. This study is important because it is the first to explore the effects of dopamine on survival, albeit short term. The delivery of dopamine into the airspaces in vivo is also novel and builds upon previous studies describing the mechanisms by which dopamine exerts its effect by upregulating active Na⁺ transport in the lungs. Dopamine appears to increase active Na⁺ transport via activation of amiloride-sensitive sodium channels and the basolateral Na⁺/K⁺-ATPase within minutes, and it has been shown to be effective in normal lungs and several models of lung injury. This information is relevant to current clinical trials exploring the effects of alveolar fluid clearance stimulation in patients with acute lung injury.

Effect of different ventilatory strategies on local and systemic cytokine production in intact swine lungs in vivo

The purpose of the study was to investigate the effect of different ventilatory strategies on local and systemic cytokine production in swine with intact lungs in vivo after 4 h of mechanical ventilation. Twenty-five swine were anesthetized and then randomized into five groups (n = 5): (1) low tidal volume zero PEEP (LVZP); (2) medium tidal volume zero PEEP (MVZP); (3) high tidal volume zero PEEP (HVZP); (4) low tidal volume PEEP (LVP); (4) high tidal volume PEEP (HVP). Respiratory rate was adjusted to maintain normocapnia and fraction of inspired oxygen (FiO2) was 1.0. TNF-alpha and IL-10 were measured in BALF and serum at baseline, 2 h, and 4 h of MV. One animal in LVZP (2 h) and two in HVP (3 h) group died before the end of the experiment. TNF-alpha level in BALF was significantly higher in LVZP and LVP at 4 h compared to baseline and the other groups. IL-10 level in BALF was significantly higher in LVP at 4h compared to baseline and the other groups. There was a statistically significant increase in serum TNF-alpha levels at 4 h in LVP group compared to baseline and the other groups at 4 h. There was statistically significant increase in serum IL-10 levels in HVZP and LVP groups at 2 and 4 h which was significantly higher compared to the other groups at 4 h. Our results show that a) low volume MV may induce local and systemic pro- and anti-inflammatory cytokine increase b) in the presence of pro-inflammatory cytokine response there is also an anti-inflammatory response in the same compartment (lungs, circulation). c) There maybe loss of alveolar-to-systemic cytokine compartmentalization.