Pulmonary Inflation Research Articles

The combination of postmortem sevoflurane ventilation and in situ topical cooling provides improved 6 hours lung preservation in an uncontrolled DCD porcine model

BackgroundRecent clinical series on donation after uncontrolled cardiovascular death (uDCD) reported successful transplantation of lungs preserved by pulmonary inflation up to 3h post-mortem. This study aims to investigate the additive effects of in situ lowering of intrathoracic temperature and sevoflurane preconditioning on lung grafts in a porcine uDCD model. MethodsAfter uDCD induction, donor pigs were allocated to one of the following groups: Control – static lung inflation only (SLI); TC – SLI + continuous intrapleural topical cooling (TC); or TC+Sevo – SLI + TC + sevoflurane. Lungs were retrieved 6h post-asystole and evaluated via ex vivo lung perfusion (EVLP) for 6h. A left single lung transplant was performed using lungs from the best performing group, followed by 4h of graft evaluation. ResultsAnimals that received topical cooling achieved intrathoracic temperature < 15°C within 1 hour after chest filling of coolant. Only lungs from donors that received TC and TC+Sevo completed the planned post-preservation 6h EVLP assessment. Despite similar early performance of the two groups on EVLP, the TC+Sevo group was superior - associated with overall lower airway pressures, higher pulmonary compliances, less edema development, and less release of inflammatory cytokines. Transplantation was performed using lungs from the TC+Sevo group, and excellent graft function was observed post-reperfusion. ConclusionPreservation of uDCD lungs with a combination of static lung inflation, topical cooling and sevoflurane treatment maintains good pulmonary function up to 6h post-mortem with excellent early post-lung transplant function. These interventions may significantly expand the clinical utilization of uDCD donor lungs.

Number of attempts and interventions to obtain a valid pulmonary artery wedge pressure.

A valid pulmonary artery wedge pressure (PAWP) is essential for the hemodynamic characterization of pulmonary hypertension (PH). We prospectively investigated the methodology for obtaining a valid PAWP measurement, while assessing the impact of prespecified factors on its determination. In this prospective observational cohort study, we included consecutive patients who underwent right heart catheterization (RHC) using fluoroscopy at the Pulmonary Vascular Disease program at Cleveland Clinic, between February and May 2023. Once a valid PAWP was obtained, we recorded the number of attempts, reason for repeating the determination, pulmonary artery location, depth of the pulmonary artery catheter (PAC) from the introducer hub, and inflation volume of the PAC balloon. We included 195 patients, age: 57.5±15.7 years, 111 (57%) women, 156 (80%) with PH. The PAWP was 16.4±5.9 mmHg, requiring 1, 2 and ≥3 attempts for a valid measurement in 139 (71%), 39 (20%) and 17 (9%) patients, respectively. PAWP was repeated due to abnormal waveform, incomplete wedge and over wedge. A valid PAWP was obtained in the right pulmonary circulation in 168 (86%) patients, and in the lower third in 134 (69%), middle third in 58 (30%), and upper third of the lung in 3 (2%) patients. The pulmonary artery catheter balloon inflation at valid PAWP was 1.0±0.3 mL, at a distance from the introducer hub of 52.6±5.2 cm. Aspiration of blood in PAW position was obtained in 141 (72%) patients with an arterial oxygenation of 97% (95-99%). The number of measurements for a valid PAWP was directly associated with mean pulmonary artery pressure (mPAP) (r=0.18, P=0.01), PAWP (r=0.22, P=0.002), and pulmonary artery diameter on computed tomography (r=0.16, P=0.04). A valid PAWP was obtained during the first or second attempt in about 90% of patients that undergo RHC. Advanced interventions such as relocating the PAC to a different place of the same lung or contralateral pulmonary circulation are needed in about 10% of patients.

Discrepancy Between Achieved and Vendor-Predicted Ablation Zones in the Lung: Contributing Factors.

Several factors are known to affect lung ablation zones. Questions remain as to why there are discrepancies between achieved and vendor-predicted ablation zones and what contributing factors can be modified to balance therapeutic effects with avoidance of complications. This retrospective study of lung tumour microwave ablation analyses day 1 post-treatment CT to assess the effects of lesion-specific and operator-dependent factors on ablation zones. Consecutive patients treated at a tertiary centre from 2018 to 2021 were included. All ablations were performed using a single microwave ablation device under lung isolation. The lung tumours were categorised as primary or secondary, and their "resistance" to ablation was graded according to their locations. Intraprocedural pulmonary inflation was assessed as equal to or less than the contralateral non-isolated lung. Ablation energy was categorised as high, medium, or low. Ablation zone dimensions were measured on day 1 CT and compared to vendor reference charts. Ablations with multiple needle positions or indeterminate boundaries were excluded. A total of 47 lesions in 31 patients were analysed. Achieved long axes are longer than predicted by 5mm or 14% (p < 0.01) without overall short axis discrepancy. Secondary tumours (p = 0.020), low-resistance location (p < 0.01), good lung inflation (p < 0.01), low (p = 0.003) and medium (p = 0.038) total energy produce lengthened long axes by 4-6mm or 10-19%. High total energy results in shorter than predicated short axes by 6mm or 18% (p = 0.010). We identified several factors affecting ablation zone dimensions which may have implications for ablation planning and the avoidance of complications.

Prognosis and outcome of intrauterine treatment of fetuses with critical congenital heart disease.

Intrauterine valvuloplasty is an innovative therapy, which promotes ventricular growth and function in some congenital heart diseases (CHDs). The technique remains challenging and can only be performed in a few centers. This study aimed to assess the feasibility and mid-term outcomes of fetal cardiac intervention (FCI) in fetuses with critical CHD in an experienced tertiary center. Five fetal aortic valvuloplasty (FAV) or fetal pulmonary valvuloplasty (FPV) procedures were performed in our fetal heart center between August 2018 and May 2022. Technical success was defined as crossing the aortic or pulmonary valve and balloon inflation, followed by evidence of increased blood flow across the valve and/or new regurgitation. Follow-up clinical records and echocardiography were obtained during the prenatal and postnatal periods. Five fetuses received FAV or FPV, including critical aortic stenosis ( n = 2) and pulmonary atresia with intact ventricular septum ( n = 3). The mean maternal age was 33.0 ± 2.6 years. The median gestational age (GA) at diagnosis was 24 weeks (range, 22-26 weeks). The median GA at intervention was 29 weeks (range, 28-32 weeks). All five cases underwent successful or partially successful procedures. One patient had pulmonary valve perforation without balloon dilation. No procedure-related deaths or significant complications occurred. However, one neonatal death occurred due to heart and renal failure. The median follow-up period was 29.5 months (range, 8.0-48.0 months). The four surviving patients had achieved biventricular circulation, exhibited improved valve, and ventricular development at the last follow-up visit. Intrauterine FCI could be performed safely with good prognosis in critical CHD.

GEOMETRICAL FEATURE OF LUNG LESION IDENTIFICATION USING COMPUTED TOMOGRAPHY SCAN IMAGES

Lung lesion identification is an important aspect of an early lung cancer diagnosis. Early identification of lung cancer may assist physicians in treating patients. This paper uses computed tomography scan images to present a lung lesion identification geometrical feature. From the previous studies, lung segmentation is particularly challenging because differences in pulmonary inflation with an elastic chest wall can result in significant variability in volumes and margins when attempting to automate lung segmentation. Besides, the features used to describe a lung lesion focus on image features which are geometric, appearance, texture, and others. This study develops an image processing technique that uses image segmentation algorithms to segment lung lesions in computed tomography images. The suggested approach includes the following stages, which require image processing techniques: data collection, image segmentation, and performance evaluation. The computed tomography scan images were collected from Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia database. As a contribution to biomedical engineering, this study has successfully calculated the performance of the image processing method for lung segmentation, which gets an average accuracy of 99.38%, recall is 99.45%, and F-score is 99.6. The lung lesion segmentation approach based on the object's size could help investigate image abnormality for medical analysis. From the study, 80% of the total lesion identification using the proposed method was correctly predicted when compared with the radiologist's lesion mark. The experiment results found clear support for the next stage of this research.

Mouse lung mechanical properties under varying inflation volumes and cycling frequencies

Respiratory pathologies alter the structure of the lung and impact its mechanics. Mice are widely used in the study of lung pathologies, but there is a lack of fundamental mechanical measurements assessing the interdependent effect of varying inflation volumes and cycling frequency. In this study, the mechanical properties of five male C57BL/6J mice (29–33 weeks of age) lungs were evaluated ex vivo using our custom-designed electromechanical, continuous measure ventilation apparatus. We comprehensively quantify and analyze the effect of loading volumes (0.3, 0.5, 0.7, 0.9 ml) and breathing rates (5, 10, 20 breaths per minute) on pulmonary inflation and deflation mechanical properties. We report means of static compliance between 5.4–16.1 µl/cmH2O, deflation compliance of 5.3–22.2 µl/cmH2O, percent relaxation of 21.7–39.1%, hysteresis of 1.11–7.6 ml•cmH2O, and energy loss of 39–58% for the range of four volumes and three rates tested, along with additional measures. We conclude that inflation volume was found to significantly affect hysteresis, static compliance, starting compliance, top compliance, deflation compliance, and percent relaxation, and cycling rate was found to affect only hysteresis, energy loss, percent relaxation, static compliance and deflation compliance.

The Combination of Post-Mortem Sevoflurane Ventilation and In Situ Topical Cooling Provides Improved 6h Lung Preservation in an Uncontrolled DCD Porcine Model

Purpose Recent clinical series on donation after uncontrolled cardiac death (uDCD) reported successful transplantation of lungs preserved by pulmonary inflation up to 3h post-mortem. This study aims to investigate the additive effects of in situ lowering of intrathoracic temperature and sevoflurane preconditioning on lung grafts in a porcine uDCD model. Methods After uDCD induction, donor pigs were allocated to one of the following groups: (1) static lung inflation only (SLI); (2) SLI + continuous intrapleural topical cooling (TC); or (3) sevoflurane preconditioning (30 min) + SLI + TC. Six hours post-asystole, lungs were retrieved and evaluated via ex vivo lung perfusion (EVLP) for 6 hours. The group with best performance on EVLP was then evaluated by transplantation in the 2nd phase of the study. Grafts were reperfused for 4h, followed by right pulmonary hilar clamping to evaluate graft oxygenation and ventilatory mechanics. Results A target intrathoracic temperature < 15°C was achieved within 1 hour of chest filling in groups 2 and 3. All lungs in group 1 failed - i.e., met EVLP termination criteria in 1h (Fig.1A). At 1h lungs from group 3 presented lower PVR, lower airway pressures, higher compliances and a higher P/F ratio compared to group 1 (Fig.1B). Despite similar early performance of groups 2 and 3, group 3 showed lower airway pressures and higher pulmonary compliances at the final hour (Fig.1C). Post-EVLP lung weight (edema) was higher in group 1 compared to groups 2 and 3 (Fig.1B). Post-transplant graft assessment in group 3 showed good oxygenation throughout the post-reperfusion observation period (Fig.1D). Conclusion Preservation of uDCD lungs with sevoflurane + static lung inflation + topical cooling maintains good pulmonary function up to 6h post-mortem with excellent early post-lung transplant function. These interventions could potentially help expand the clinical utilization of uDCD donor lungs for transplantation. Recent clinical series on donation after uncontrolled cardiac death (uDCD) reported successful transplantation of lungs preserved by pulmonary inflation up to 3h post-mortem. This study aims to investigate the additive effects of in situ lowering of intrathoracic temperature and sevoflurane preconditioning on lung grafts in a porcine uDCD model. After uDCD induction, donor pigs were allocated to one of the following groups: (1) static lung inflation only (SLI); (2) SLI + continuous intrapleural topical cooling (TC); or (3) sevoflurane preconditioning (30 min) + SLI + TC. Six hours post-asystole, lungs were retrieved and evaluated via ex vivo lung perfusion (EVLP) for 6 hours. The group with best performance on EVLP was then evaluated by transplantation in the 2nd phase of the study. Grafts were reperfused for 4h, followed by right pulmonary hilar clamping to evaluate graft oxygenation and ventilatory mechanics. A target intrathoracic temperature < 15°C was achieved within 1 hour of chest filling in groups 2 and 3. All lungs in group 1 failed - i.e., met EVLP termination criteria in 1h (Fig.1A). At 1h lungs from group 3 presented lower PVR, lower airway pressures, higher compliances and a higher P/F ratio compared to group 1 (Fig.1B). Despite similar early performance of groups 2 and 3, group 3 showed lower airway pressures and higher pulmonary compliances at the final hour (Fig.1C). Post-EVLP lung weight (edema) was higher in group 1 compared to groups 2 and 3 (Fig.1B). Post-transplant graft assessment in group 3 showed good oxygenation throughout the post-reperfusion observation period (Fig.1D). Preservation of uDCD lungs with sevoflurane + static lung inflation + topical cooling maintains good pulmonary function up to 6h post-mortem with excellent early post-lung transplant function. These interventions could potentially help expand the clinical utilization of uDCD donor lungs for transplantation.

Effect of pulmonary artery catheter balloon inflation on pulmonary hemodynamics.

Right heart catheterization (RHC), including a pulmonary artery wedge pressure (PAWP) determination, is necessary to categorize the hemodynamic type of pulmonary hypertension (PH). The potential hemodynamic implications of a pulmonary artery catheter (PAC) balloon inflation in PH have not been formally tested. We assessed the hemodynamic impact of the PAC balloon inflation during RHC by measuring systolic, diastolic, and mean pulmonary artery pressure (mPAP) in all patients, and cardiac output (CO) by thermodilution in a subgroup of patients. Hemodynamic measurements were obtained both with PAC balloon deflated and fully inflated (1.5 mL of air), while the PAC was free floating in the pulmonary artery before wedging. We calculated total pulmonary resistance (TPR). We included 210 patients, age 58±14 years, 134 (64%) women. Patients had no PH (n: 12, 6%), PH group 1 (n: 68, 33%), 2 (n: 86, 41%), 3 (n: 11, 5%), 4 (n: 29, 14%), and 5 (n: 3, 1%). The mean ± standard deviation (SD) at end-expiration mPAP (balloon-up minus down) (n: 209) was -0.02±1.59 mmHg (range, -5.0 to 4.0 mmHg; P=0.84), while the TPR (n: 62) was -0.27±1.2 Wood units (WU) (range, -4.8 to 2.2 WU; P=0.08); without significant variation based on the type of PH group or degree of pulmonary vascular resistance (PVR). Interestingly, the change in mPAP at end-expiration with PAC balloon inflation was higher in women (mean ± SD: 0.31±1.43 mmHg) than men (mean ± SD: -0.61±1.70 mmHg) (P<0.001). Balloon inflation of the PAC in the main pulmonary artery had no significant impact on the mPAP or TPR, even when only including patients with group 1 PH or selecting a subgroup with a higher PVR.

Comparison of Intraperitoneal Normal Saline Infusion with Pulmonary Recruitment Maneuver in Reducing Shoulder and Upper Abdomen Pain Following Gynecologic Laparoscopic Procedures: A Randomized, Controlled, Triple-Blind Trial.

ObjectivesThe current study aimed at evaluating the effect of intraperitoneal infusion of normal saline (NS) and pulmonary recruitment maneuver (PRM) on the reduction of pain in shoulder, upper abdomen, and incision site after elective laparoscopic gynecologic surgery.MethodsTotally, 280 patients (mean age: 30.5 years) that underwent laparoscopic gynecologic surgery from October 2013 to August 2015 were randomly and equally allocated into four groups. Group A received intraperitoneal infusion of NS 1.5 - 2 mL/kg of body weight; group B received PRM with five manual pulmonary inflations at a maximum pressure of 60 cm H2O; group C simultaneously received two former interventions; and finally the control group D received routine method of gentle abdominal pressure. All patients were assessed in the first 24 hours after surgery.ResultsThere was an unsteady pattern for pain in shoulder, upper abdomen, and incision site at different time points across the studied groups over the trial. Patients in group B showed significantly lower shoulder pain 24 hours after laparoscopic gynecologic surgery (P = 0.01), while patients in group D had significantly lower incision site pain (P < 0.001).ConclusionsPRM was superior to intraperitoneal infusion of NS for reducing pain in the first 24 hours after laparoscopic gynecologic surgery.

Hypoxia-induced vagal withdrawal is independent of the hypoxic ventilatory response in men.

Hypoxia increases heart rate (HR) in humans by sympathetic activation and vagal withdrawal. However, in anaesthetized dogs hypoxia increases vagal activity and reduces HR if pulmonary ventilation does not increase and we evaluated whether that observation applies to awake humans. Ten healthy males were exposed to 15 min of normoxia and hypoxia (10.5% O2), while respiratory rate and tidal volume were volitionally controlled at values identified during spontaneous breathing in hypoxia. End-tidal CO2 tension was clamped at 40 mmHg by CO2 supplementation. β-Adrenergic blockade by intravenous propranolol isolated vagal regulation of HR. During spontaneous breathing, hypoxia increased ventilation by 3.2 ± 2.1 l/min ( P = 0.0033) and HR by 8.9 ± 5.5 beats/min ( P < 0.001). During controlled breathing, respiratory rate (16.3 ± 3.2 vs. 16.4 ± 3.3 breaths/min) and tidal volume (1.05 ± 0.27 vs. 1.06 ± 0.24 l) were similar for normoxia and hypoxia, whereas the HR increase in hypoxia persisted without (8.6 ± 10.2 beats/min) and with (6.6 ± 5.6 beats/min) propranolol. Neither controlled breathing ( P = 0.80), propranolol ( P = 0.64), nor their combination ( P = 0.89) affected the HR increase in hypoxia. Arterial pressure was unaffected ( P = 0.48) by hypoxia across conditions. The hypoxia-induced increase in HR during controlled breathing and β-adrenergic blockade indicates that hypoxia reduces vagal activity in humans even when ventilation does not increase. Vagal withdrawal in hypoxia seems to be governed by the arterial chemoreflex rather than a pulmonary inflation reflex in humans. NEW & NOTEWORTHY Hypoxia accelerates the heart rate of humans by increasing sympathetic activity and reducing vagal activity. Animal studies have indicated that hypoxia-induced vagal withdrawal is governed by a pulmonary inflation reflex that is activated by the increased pulmonary ventilation in hypoxia. The present findings, however, indicate that humans experience vagal withdrawal in hypoxia even if ventilation does not increase, indicating that vagal withdrawal is governed by the arterial chemoreflex rather than a pulmonary inflation reflex.

Comparison of impacts of intraperitoneal saline instillation with and without pulmonary recruitment maneuver on post-laparoscopic shoulder pain prevention: a randomized controlled trial.

Intraperitoneal isotonic saline instillation (SI) and pulmonary recruitment maneuver (RM) were indicated to alleviate post-laparoscopic shoulder pain (PLSP) effectively. The aim of this study was to compare the effects of the single strategy using SI alone and the combined strategy using SI and RM on PLSP reduction. Subjects undergoing elective gynecologic laparoscopy were randomly allocated to a control group (no intervention, n = 48) and two intervention groups (single strategy of SI alone, n = 48; combined strategy of SI and RM, n = 48). In the control group, carbon dioxide was removed only via passive evacuation through the port sites at the completion of the laparoscopic procedure. In the saline instillation group, 20-mL/kg of body weight SI was performed. In the combined strategy group, RM using five pulmonary inflations was performed, in addition to SI. The PLSP scores, which were the primary outcome, were recorded using a visual analog scale postoperatively. The PLSP scores 24 and 48h after surgery were significantly lower in the two intervention groups than in the control group (P = 0.014 and P = 0.001, respectively), while no significant differences were observed between the two intervention groups. The single strategy using SI alone is as effective as the combined strategy of SI and RM for removing residual carbon dioxide and consequently preventing PLSP. Therefore, considering the potential risks of pulmonary or hemodynamic complications associated with RM, the single strategy using SI alone might be a better choice than the combined strategy.

Pulmonary static inflation with 50% xenon attenuates decline in tissue factor in patients undergoing Stanford type A acute aortic dissection repair.

The Stanford type A acute aortic dissection (AAD) carries a high risk of mortality and morbidity, and patients undergoing AAD surgery often bleed excessively and require blood products and transfusions. Thus, we studied how xenon alters coagulation using thromboelastography (TEG) and conventional hemostatic tests for patients with AAD undergoing aortic arch surgery involving cardiopulmonary bypass (CPB)/deep hypothermic circulatory arrest (DHCA). This prospective single-center nonrandomized controlled clinical trial, registered in the Chinese Clinical Trial Registry (ChiCTR-ICR-15006435), assessed perioperative clinical variables and serological results from 50 subjects undergoing pulmonary static inflation with 50% nitrogen/50% oxygen from January 2013 to January 2014 and 50 subjects undergoing pulmonary static inflation with 50% xenon/50% oxygen from January 2014 to December 2014 during CPB for Stanford type A AAD. Repeated measures ANOVA were used to identify the effects of xenon on coagulation after surgery. The primary endpoint was perioperative changes in coagulation and fibrinolysis after intubation and 10 minutes, and 6 hours after the operation. The secondary endpoint was to assess the perioperative changes in serum level of tissue factor (TF), tissue factor pathway inhibitor (TFPI) and tissue plasminogen activator (tPA) after intubation and 10 minutes, and 6 hours after the operation. Mean prothrombin time (PT), activated partial thromboplastin time (APTT), international normalized ratio (INR), median fibrinogen degradation product (FDP), and D-dimer peaked and then decreased over 6 hours after surgery. TEG followed a similar trend. From the start to the end of surgery and until 6 h after surgery, mean TF decreased in controls (β -2.61, P<0.001 and β -2.83, P<0.001, respectively), but was maintained relatively stable in xenon group (β -0.5, P<0.001 and β -0.96, P<0.001, respectively). Deterioration of coagulation function and activated fibrinolysis was confirmed by conventional tests and TEG analysis after Stanford type A AAD repair. Pulmonary static inflation with 50% xenon attenuates decline in TF in patients undergoing Stanford type A AAD repair.

Effect of the pulmonary recruitment maneuver on pain after laparoscopic gynecological oncologic surgery: a prospective randomized trial.

ObjectiveTo evaluate the effectiveness of the pulmonary recruitment maneuver (PRM) at the end of the operation to decrease laparoscopy-induced abdominal or shoulder pain after gynecological oncologic surgery.MethodsIn total, 113 women undergoing laparoscopic surgery for malignant or premalignant gynecological lesions were assigned randomly to two groups: the PRM group (the patient was placed in the Trendelenburg position (30°) and the PRM, consisting of two manual pulmonary inflations to a maximum pressure of 40 cmH2O) (n=54) and the control group (n=52). Postoperative shoulder and abdominal pain was assessed 12, 24, and 48 hours later using a visual analog scale (0–10). In addition, the incidence of post-discharge nausea and vomiting was recorded until 48 hours after discharge.ResultsPostoperative shoulder pain at 12 and 24 hours was significantly less severe in the PRM group (2.2±0.5 and 2.0±0.4) than in the control group (4.0±0.5 and 3.9±0.4; both p<0.001). The PRM significantly reduced the severity of upper abdominal pain at 12 and 24 h compared with the control group (3.1±0.4 and 2.9±0.4 vs. 5.9±0.5 and 4.9±0.5; both p<0.001). The analgesic requirement during the postoperative period was similar in the two groups (control group, 78.8%; PRM group, 75.9%; p=0.719).ConclusionThe PRM effectively and safely reduced postoperative shoulder and upper abdominal pain levels in patients undergoing laparoscopic gynecological oncologic surgery. Trial registry at ClinicalTrials.gov, NCT01940042.

Protection of xenon against postoperative oxygen impairment in adults undergoing Stanford Type-A acute aortic dissection surgery: Study protocol for a prospective, randomized controlled clinical trial.

Objectives:The available evidence shows that hypoxemia after Stanford Type-A acute aortic dissection (AAD) surgery is a frequent cause of several adverse consequences. The pathogenesis of postoperative hypoxemia after AAD surgery is complex, and ischemia/reperfusion and inflammation are likely to be underlying risk factors. Xenon, recognized as an ideal anesthetic and anti-inflammatory treatment, might be a possible treatment for these adverse effects.Methods/Design:The trial is a prospective, double-blind, 4-group, parallel, randomized controlled, a signal-center clinical trial. We will recruit 160 adult patients undergoing Stanford type-A AAD surgery. Patients will be allocated a study number and will be randomized on a 1:1:1:1 basis to receive 1 of the 3 treatment options (pulmonary inflated with 50% xenon, 75% xenon, or 100% xenon) or no treatment (control group, pulmonary inflated with 50% nitrogen). The aims of this study are to clarify the lung protection capability of xenon and its possible mechanisms in patients undergoing the Stanford type-A AAD surgery.Discussion:This trial uses an innovative design to account for the xenon effects of postoperative oxygen impairment, and it also delineates the mechanism for any benefit from xenon. The investigational xenon group is considered a treatment intervention, as it includes 3 groups of pulmonary static inflation with 50%, 75%, and 100% xenon. It is suggested that future trials might define an appropriate concentration of xenon for the best practice intervention.

The impact of a pulmonary recruitment maneuver to reduce post-laparoscopic shoulder pain: A randomized controlled trial

ObjectiveA pulmonary recruitment maneuver (PRM) can effectively reduce post-laparoscopic shoulder pain (PLSP). However, a high-pressure PRM may cause pulmonary barotrauma. This study aimed to evaluate the efficacy and safety of a PRM using two different maximum inspiratory pressures (40 and 60cmH2O) for reducing PLSP. Study designPatients undergoing gynecologic laparoscopy were randomly allocated to a control group (n=30), a 40 cmH2O PRM group (n=30), and a 60 cmH2O PRM group (n=30). In the control group, residual carbon dioxide was removed by passive exsufflation through the port site. In the two intervention groups, the PRM consisting of five manual pulmonary inflations was performed at the end of surgery with a maximum pressure of 40 cmH2O or 60 cmH2O, respectively. Shoulder pain and wound pain were recorded using a visual analogue scale at 24 and 48h postoperatively. ResultsWound pain scores at 24 and 48h post-surgery were not different between the three groups. The PLSP scores in the two intervention groups were significantly lower than that seen in the control group at 24 and 48h postoperatively (P=0.006 and P<0.001, respectively). However, there were no statistically significant differences in the PLSP scores between the two intervention groups. ConclusionA low-pressure PRM (40cmH2O) is as effective as a high-pressure PRM (60cmH2O) for removing residual gas from the peritoneal cavity. PRM using a maximal inspiratory pressure of 40cmH2O is safe and efficacious for the reduction of PLSP.

Effect of sustained inflation with different degrees of negative pressure for sputum aspiration in patients with acute respiratory distress syndrome on lung recruitment

To investigate the effect of different degrees of pressure of sustained inflation (SI) in patients with acute respiratory distress syndrome (ARDS) after lung recruitment as the result of different negative pressure for sputum aspiration. A prospective single-blind randomized controlled trial was conducted. The factorial analysis of variance was adopted. 150 patients with ARDS admitted to the emergency intensive care unit (ICU) of Chongqing Three Gorges Central Hospital from January 2012 to December 2014 were enrolled, and they were randomly divided into S1, S2, S3 group, with 50 patients in each group, suction pressure varying from 150, 175, to 200 mmHg (1 mmHg=0.133 kPa) was respectively used in each group. Then the patients of each group were randomly subdivided into five subgroups of P0, P1, P2, P3, P4, with 10 patients in each group, and 0, 30, 35, 40, and 45 cmH2O (1 cmH2O=0.098 kPa) were used for control pulmonary inflation pressure, respectively. The respiratory mechanics and the hemodynamic parameters were recorded, and they were compared before and after the sputum aspiration as well as lung recruitment with sustained inflation. The lung recruitment volume (mL: 87.56±28.47 vs. 109.38±34.63, t=3.573, P=0.001) and lung static compliance [Cst (mL/cmH2O): 27.69±13.25 vs. 35.87±17.47, t=2.814, P=0.004] after sputum aspiration in the 150 patients were significantly lower than those before the sputum aspiration, and peak airway pressure [PIP (cmH2O): 24.16±8.28 vs. 18.63±6.67, t=2.957, P=0.005], airway plateau pressure [Pplat (cmH2O): 21.28±9.14 vs. 17.47±7.26, t=2.089, P=0.032], and mean airway pressure [Pm (cmH2O): 13.26±4.65 vs. 10.41±3.54, t=3.271, P=0.001] were significantly higher than those before the treatment. There were no significant differences in the lung recruitment volume, Cst, PIP, Pplat and Pm between groups with different negative pressure for sputum aspiration (F value was 0.809, 0.986, 1.121, 0.910, 1.043, and P value was 0.452, 0.381, 0.335, 0.410, 0.361), but statistical significance was found among different groups of different lung recruitment pressures (F value was 3.581, 5.028, 3.064, 3.036, 4.050, and P value was 0.013, 0.002, 0.026, 0.027, 0.007). There was no interaction between the two factors. After pairwise comparison, under the same negative pressure for sputum aspiration, lung recruitment volume and Cst in different lung recruitment pressures subgroups (P1, P2, P3, P4) were significantly higher than those of P0 subgroup, and PIP, Pplat, and Pm were significantly lower than those of P0 subgroup. There was no significant difference among P1, P2, P3 and P4 groups. There were no significant differences in mean arterial pressure (MAP) and pulmonary arterial pressure (PAP) among different groups with negative pressures for sputum aspiration and different lung recruitment pressures (negative pressure for sputum aspiration: F=0.586, P=0.561, F=1.373, P=0.264; lung recruitment pressure: F=1.313, P=0.280, F=1.621, P=0.186), there was no interaction between the two factors (F=0.936, P=0.497, F=1.391, P=0.227). The difference of heart rate (HR) in different negative pressure for sputum aspiration groups was not significant (F=1.144, P=0.328), and there were significant differences in different lung recruitment pressure groups (F=3.297, P=0.019), there was no interaction between the two factors (F=1.277, P=0.280). After pairwise comparison, under the same negative pressure for sputum aspiration, HR in P3 and P4 subgroups was significantly higher than that in P0, P1, and P2 subgroups (all P<0.05). 30 cmH2O and 35 cmH2O were the suitable pressure for SI in ARDS patients, and they were not affected by different negative pressure for sputum aspiration.

0897. Mechanisms of pulmonary inflation during lung injury assessed by synchrotron radiation computed tomography

The process of lung inflation during mechanical ventilation is characterized by phenomena of alveolar recruitment and distension but regional interaction and temporal sequence are not known for the core areas of the lung. The only information available are referred to subpleural alveoli, studied by microscopy. Relevance of this issue derives from the notion that 1) radiologic studies reveal that air spaces behavior in the core regions of the parenchyma is very complex 2) unsuited patterns of mechanical ventilation (MV) can trigger a Ventilator-Induced Lung Injury (VILI). Synchrotron Radiation Computed Tomography (SRCT) yields tomographic images at resolutions higher than conventional CT.

Effects of pulmonary static inflation with different pressures on postoperative lung function in patients undergoing cardiac valve replacement with cardiopulmonary bypass

Objective To evaluate the effects of pulmonary static inflation with different pressures on postoperative lung function in patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB).Methods Sixty ASA Ⅱ or Ⅲ patients,aged 26-70 yr,weighing 47-78 kg,undergoing elective cardiac valve replacement with CPB,were randomly divided into 2 groups (n =30 each):pulmonary static inflation with 5 cm H2O group (group L) and with 10 cm H2O group (group H).In L and H groups,pulmonary static inflation was performed with the pressure maintained at 5 and 10 cm H2O,respectively,after stopping mechanical ventilation during CPB.Arterial blood samples were taken before skin incision and at 1,3 and 6 h after termination of CPB for blood gas analysis.The alveolar-arterial oxygen pressure difference (D(A-a)O2),respiratory index (RI) and oxy.genation index (OI) were calculated.The indwelling time of endotracheal tube after operation and duration of ICU stay were recorded.Results Compared with group L,D(A-a)O2 and RI were significantly decreased and OI was increased at 1,3 and 6 h after termination of CPB,the incidence of OI less than 300 mm Hg was decreased (P ＜ 0.05),and no significant change was found in the indwelling time of endotracheal tube after operation and duration of ICU stay in H group (P ＞ 0.05).Collusion Pulmonary static inflation with 10 cm H2O can better improve postoperative pulmonary diffusion function than with 5 cm H2O in patients undergoing cardiac valve replacement with CPB. Key words: Pressure; Extracorporeal circulation; Respiratory function tests; Pulmonary static inflation

Inter-individual differences in breathing pattern at high levels of incremental cycling exercise in healthy subjects

Interindividual differences in the rate of changes in tidal volume (VT) and respiratory frequency (fR) were examined during a maximal incremental cycling exercise. The gain of the inspiratory off-switch reflex was inferred from the VT vs. inspiratory duration (Ti) relationship. Some subjects also executed a static handgrip exercise, used as a “non-dynamic” exercise trial to study patterning of breathing.Above the ventilatory threshold (VTh), two patterns of response were identified: in group 1, the rate of change in VT significantly increased, while in group 2 the breakpoint of ventilation solely resulted from fR increase. After the respiratory compensation point, a tachypnoeic response always occurred. A leftward shift of the VT vs. Ti relationship, i.e., an inspiratory off-switch reflex, was measured during the handgrip in group 2 subjects as well as marked fR variations.Our study identifies two different patterns of breathing after the VTh. The subjects who present a tachypnoeic response to exercise above the VTh have a higher sensitivity to pulmonary inflation and their tachypnoeic response was ubiquitous during a maximal handgrip test.

Low Voltage Vagal Nerve Stimulation Reduces Bronchoconstriction in Guinea Pigs Through Catecholamine Release

Electrical stimulation of the vagus nerve at relatively high voltages (e.g., >10 V) can induce bronchoconstriction. However, low voltage (≤2 V) vagus nerve stimulation (VNS) can attenuate histamine-invoked bronchoconstriction. Here, we identify the mechanism for this inhibition. In urethanea-nesthetized guinea pigs, bipolar electrodes were attached to both vagus nerves and changes in pulmonary inflation pressure were recorded in response to i.v. histamine and during VNS. The attenuation of the histamine response by low-voltage VNS was then examined in the presence of pharmacologic inhibitors or nerve ligation. Low-voltage VNS attenuated histamine-induced bronchoconstriction (4.4 ± 0.3 vs. 3.2 ± 0.2 cm H(2) O, p < 0.01) and remained effective following administration of a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester, and after sympathetic nerve depletion with guanethidine, but not after the β-adrenoceptor antagonist propranolol. Nerve ligation caudal to the electrodes did not block the inhibition but cephalic nerve ligation did. Low-voltage VNS increased circulating epinephrine and norepinephrine without but not with cephalic nerve ligation. These results indicate that low-voltage VNS attenuates histamine-induced bronchoconstriction via activation of afferent nerves, resulting in a systemic increase in catecholamines likely arising from the adrenal medulla.