Chest Wall Mechanics Research Articles

Transpulmonary Pressure as a Predictor of Successful Lung Recruitment: Reanalysis of a Multicenter International Randomized Clinical Trial.

Recruitment maneuvers are used in patients with ARDS to enhance oxygenation and lung mechanics. Heterogeneous lung and chest-wall mechanics lead to unpredictable transpulmonary pressures and could impact recruitment maneuver success. Tailoring care based on individualized transpulmonary pressure might optimize recruitment, preventing overdistention. This study aimed to identify the optimal transpulmonary pressure for effective recruitment and to explore its association with baseline characteristics. We performed post hoc analysis on the Esophageal Pressure Guided Ventilation (EpVent2) trial. We estimated the dose-response relationship between end-recruitment end-inspiratory transpulmonary pressure and the change in lung elastance after a recruitment maneuver by using logistic regression weighted by a generalized propensity score. A positive change in lung elastance was indicative of overdistention. We examined how patient characteristics, disease severity markers, and respiratory parameters predict transpulmonary pressure by using multivariate linear regression models and dominance analyses. Of 121 subjects, 43.8% had a positive change in lung elastance. Subjects with a positive change in lung elastance had a mean ± SD transpulmonary pressure of 15.1 ± 4.9 cm H2O, compared with 13.9 ± 3.9 cm H2O in those with a negative change in lung elastance. Higher transpulmonary pressure was associated with increased probability of a positive change in lung elastance (adjusted odds ratio 1.35 per 1 cm H2O of transpulmonary pressure, 95% CI 1.13-1.61; P = .001), which indicated an S-shaped dose-response curve, with overdistention probability > 50% at transpulmonary pressure values > 18.3 cm H2O. The volume of recruitment was transpulmonary pressure-dependent (P < .001; R2 = 0.49) and inversely related to a change in lung elastance after adjusting for baseline lung elastance (P < .001; R2= 0.43). Negative correlations were observed between transpulmonary pressure and body mass index, PEEP, Sequential Organ Failure Assessment score, and PaO2 /FIO2 , whereas baseline lung elastance showed a positive correlation. The body mass index emerged as the dominant negative predictor of transpulmonary pressure (ranking 1; contribution to R2 = 0.08), whereas pre-recruitment elastance was the sole positive predictor (contribution to R2 = 0.06). Higher end-recruitment transpulmonary pressure increases the volume of recruitment but raises the risk of overdistention, providing the rationale for transpulmonary pressure to be used as a clinical target. Predictors, for example, body mass index, could guide recruitment maneuver individualization to balance adequate volume gain with overdistention.

Impact of the transpulmonary pressure on right ventricle impairment incidence during acute respiratory distress syndrome: a pilot study in adults and children

BackgroundRight ventricle impairment (RVI) is common during acute respiratory distress syndrome (ARDS) in adults and children, possibly mediated by the level of transpulmonary pressure (PL). We sought to investigate the impact of the level of PL on ARDS-associated right ventricle impairment (RVI).MethodsAdults and children (> 72 h of life) were included in this two centers prospective study if they were ventilated for a new-onset ARDS or pediatric ARDS, without spontaneous breathing and contra-indication to esophageal catheter. Serial measures of static lung, chest wall, and respiratory mechanics were coupled to critical care echocardiography (CCE) for 3 days. Mixed-effect logistic regression models tested the impact of lung stress (ΔPL) along with age, lung injury severity, and carbon dioxide partial pressure, on RVI using two definitions: acute cor pulmonale (ACP), and RV dysfunction (RVD). ACP was defined as a dilated RV with septal dyskinesia; RVD was defined as a composite criterion using tricuspid annular plane systolic excursion, S wave velocity, and fractional area change.Results46 patients were included (16 children, 30 adults) with 106 CCE (median of 2 CCE/patient). At day one, 19% of adults and 4/7 children > 1 year exhibited ACP, while 59% of adults and 44% of children exhibited RVD. In the entire population, ACP was present on 17/75 (23%) CCE. ACP was associated with an increased lung stress (mean ΔPL of 16.2 ± 6.6 cmH2O in ACP vs 11.3 ± 3.6 cmH2O, adjusted OR of 1.33, CI95% [1.11–1.59], p = 0.002) and being a child. RVD was present in 59/102 (58%) CCE and associated with lung stress. In children > 1 year, PEEP was significantly lower in case of ACP (9.3 [8.6; 10.0] cmH2O in ACP vs 15.0 [11.9; 16.3] cmH2O, p = 0.03).ConclusionLung stress was associated with RVI in adults and children with ARDS, children being particularly susceptible to RVI.Trial registration Clinical trials identifier: NCT0418467.

Stress–strain curve and elastic behavior of the fibrotic lung with usual interstitial pneumonia pattern during protective mechanical ventilation

Patients with acute exacerbation of lung fibrosis with usual interstitial pneumonia (EUIP) pattern are at increased risk for ventilator-induced lung injury (VILI) and mortality when exposed to mechanical ventilation (MV). Yet, lack of a mechanical model describing UIP-lung deformation during MV represents a research gap. Aim of this study was to develop a constitutive mathematical model for UIP-lung deformation during lung protective MV based on the stress–strain behavior and the specific elastance of patients with EUIP as compared to that of acute respiratory distress syndrome (ARDS) and healthy lung. Partitioned lung and chest wall mechanics were assessed for patients with EUIP and primary ARDS (1:1 matched based on body mass index and PaO2/FiO2 ratio) during a PEEP trial performed within 24 h from intubation. Patient’s stress–strain curve and the lung specific elastance were computed and compared with those of healthy lungs, derived from literature. Respiratory mechanics were used to fit a novel mathematical model of the lung describing mechanical-inflation-induced lung parenchyma deformation, differentiating the contributions of elastin and collagen, the main components of lung extracellular matrix. Five patients with EUIP and 5 matched with primary ARDS were included and analyzed. Global strain was not different at low PEEP between the groups. Overall specific elastance was significantly higher in EUIP as compared to ARDS (28.9 [22.8–33.2] cmH2O versus 11.4 [10.3–14.6] cmH2O, respectively). Compared to ARDS and healthy lung, the stress/strain curve of EUIP showed a steeper increase, crossing the VILI threshold stress risk for strain values greater than 0.55. The contribution of elastin was prevalent at lower strains, while the contribution of collagen was prevalent at large strains. The stress/strain curve for collagen showed an upward shift passing from ARDS and healthy lungs to EUIP lungs. During MV, patients with EUIP showed different respiratory mechanics, stress–strain curve and specific elastance as compared to ARDS patients and healthy subjects and may experience VILI even when protective MV is applied. According to our mathematical model of lung deformation during mechanical inflation, the elastic response of UIP-lung is peculiar and different from ARDS. Our data suggest that patients with EUIP experience VILI with ventilatory setting that are lung-protective for patients with ARDS.

Respiratory and chest wall mechanics in very preterm infants.

Data on static compliance of the chest wall (Ccw) in preterm infants are scarce. We characterized the static compliance of the lung (CL) and Ccw to determine their relative contribution to static compliance of the respiratory system (Crs) in very preterm infants at 36 wk postmenstrual age (PMA). We also aimed to investigate how these compliances were influenced by the presence of bronchopulmonary dysplasia (BPD) and impacted breathing variables. Airway opening pressure, esophageal pressure, and tidal volume (VT) were measured simultaneously during a short apnea evoked by the Hering-Breuer reflex. We computed tidal breathing variables, airway resistance (R), and dynamic lung compliance (CL,dyn), inspiratory capacity (IC), and Crs, CL, and Ccw. Functional residual capacity was assessed by the multiple breath washout technique (FRCmbw). Breathing variables, compliances, and lung volumes were adjusted for body weight. Twenty-three preterm infants born at 27.2 ± 2.0 wk gestational age (GA) were studied at 36.6 ± 0.6 wk PMA. Median and interquartile range (IQR) Crs/kg is 0.69 (0.6), CL/kg 0.95 (1.0), and Ccw/kg 3.0 (2.4). Infants with BPD (n = 11) had lower Crs/kg (P = 0.013), CL/kg (P = 0.019), and Ccw/kg (P = 0.027) compared with infants without BPD. Ccw/CL ratio was equal between groups. FRCmbw/kg (P = 0.044) and IC/kg (P = 0.005) were decreased in infants with BPD. Infants with BPD have reduced static compliance of the respiratory system, the lungs, and chest wall. Decreased Crs, CL, and Ccw in infants with BPD explain the lower FRC and IC seen in these infants.NEW & NOTEWORTHY Data on chest wall compliance in very preterm infants in the postsurfactant era are scarce. To our knowledge, we are the first group to report data on static respiratory system compliance (Crs), lung compliance (CL), and chest wall compliance (Ccw) in preterm infants with and without bronchopulmonary dysplasia (BPD) in the postsurfactant era.

Differential Effects of Intra-Abdominal Hypertension and ARDS on Respiratory Mechanics in a Porcine Model.

Background and Objectives: Intra-abdominal hypertension (IAH) and acute respiratory distress syndrome (ARDS) are common concerns in intensive care unit patients with acute respiratory failure (ARF). Although both conditions lead to impairment of global respiratory parameters, their underlying mechanisms differ substantially. Therefore, a separate assessment of the different respiratory compartments should reveal differences in respiratory mechanics. Materials and Methods: We prospectively investigated alterations in lung and chest wall mechanics in 18 mechanically ventilated pigs exposed to varying levels of intra-abdominal pressures (IAP) and ARDS. The animals were divided into three groups: group A (IAP 10 mmHg, no ARDS), B (IAP 20 mmHg, no ARDS), and C (IAP 10 mmHg, with ARDS). Following induction of IAP (by inflating an intra-abdominal balloon) and ARDS (by saline lung lavage and injurious ventilation), respiratory mechanics were monitored for six hours. Statistical analysis was performed using one-way ANOVA to compare the alterations within each group. Results: After six hours of ventilation, end-expiratory lung volume (EELV) decreased across all groups, while airway and thoracic pressures increased. Significant differences were noted between group (B) and (C) regarding alterations in transpulmonary pressure (TPP) (2.7 ± 0.6 vs. 11.3 ± 2.1 cmH2O, p < 0.001), elastance of the lung (EL) (8.9 ± 1.9 vs. 29.9 ± 5.9 cmH2O/mL, p = 0.003), and elastance of the chest wall (ECW) (32.8 ± 3.2 vs. 4.4 ± 1.8 cmH2O/mL, p < 0.001). However, global respiratory parameters such as EELV/kg bodyweight (-6.1 ± 1.3 vs. -11.0 ± 2.5 mL/kg), driving pressure (12.5 ± 0.9 vs. 13.2 ± 2.3 cmH2O), and compliance of the respiratory system (-21.7 ± 2.8 vs. -19.5 ± 3.4 mL/cmH2O) did not show significant differences among the groups. Conclusions: Separate measurements of lung and chest wall mechanics in pigs with IAH or ARDS reveals significant differences in TPP, EL, and ECW, whereas global respiratory parameters do not differ significantly. Therefore, assessing the compartments of the respiratory system separately could aid in identifying the underlying cause of ARF.

Oesophageal pressure monitoring in intubated patients by intensive care units' nurses: An educational study.

Trained ICU nurses may perform oesophageal pressure measurements which may help facilitate its implementation in the usual patient care to better assess lung and chest wall mechanics and easily detect patient-ventilator asynchronies. We thus conducted a prospective educational study aiming to assess the ability of ICU nurses to perform reliable oesophageal pressure measurements after a short dedicated training program. All the 11 nurses who completed the program succeeded their practical evaluation (nine (82%) at the first evaluation and two (18%) at their second attempt). These results show that this training program is feasible and that trained ICU nurses can perform accurate oesophageal pressure measurements in mechanically ventilated patients.

Influence of the chest wall on respiratory function at birth in near-term lambs.

Airway liquid is cleared into lung tissue after birth, which becomes edematous and forces the chest wall to expand to accommodate both the cleared liquid and incoming air. This study investigated how changing chest wall mechanics affects respiratory function after birth in near-term lambs with different airway liquid volumes. Surgically instrumented near-term lambs (139 ± 2 days) were randomized into Control (n = 7) or Elevated Liquid (EL; n = 6) groups. Control lambs had lung liquid drained to simulate expected volumes following vaginal delivery. EL lambs had airway liquid drained and 30 mL/kg liquid returned to simulate expected airway liquid volumes after elective cesarean section. Lambs were delivered, transferred to a Perspex box, and ventilated (30 min). Pressure in the box was adjusted to apply positive (7-8 cmH2O above atmospheric pressure) or negative (7-8 cmH2O below atmospheric pressure) pressures for 30 min before pressures were reversed. External negative pressures expanded the chest wall, reduced chest wall compliance (CCW) and increased lung compliance (CL) in Control and EL lambs. External positive pressures compressed the chest wall, increased CCW and reduced CL in Control and EL lambs. External negative pressure improved pulmonary oxygen exchange, reducing the alveolar-arterial difference in oxygen (AaDO2) by 69 mmHg (95% CI [13, 125]; P = 0.016) in Control lambs and by 300 mmHg (95% CI [233, 367]; P < 0.001) in EL lambs. In contrast, external positive pressures impaired pulmonary gas exchange, increasing the AaDO2 by 179 mmHg (95% CI [73, 285]; P = 0.002) in Control and by 215 mmHg (95% CI [89, 343]; P < 0.001) in EL lambs. The application of external thoracic pressures influences respiratory function after birth.NEW & NOTEWORTHY This study investigated how changes in chest wall mechanics influence respiratory function after birth. Our data indicate that the application of continuous external subatmospheric pressure greatly improves respiratory function in near-term lambs with respiratory distress, whereas external positive pressures impair respiratory function. Our findings indicate that, during neonatal resuscitation at birth, the forces applied to the chest wall should not be ignored as they can have a major impact on neonatal respiratory function.

High vs Low PEEP in Patients With ARDS Exhibiting Intense Inspiratory Effort During Assisted Ventilation: A Randomized Crossover Trial

BackgroundPEEP can potentially modulate inspiratory effort (ΔPes), which is the major determinant of self-inflicted lung injury. Research questionDoes high PEEP reduce ΔPes in moderate-to-severe ARDS patients on assisted ventilation? Study Design and MethodsSixteen patients with PaO2/FiO2≤200 mmHg and ΔPes≥10 cmH2O underwent a randomized sequence of four ventilator settings: PEEP=5 cmH2O or PEEP=15 cmH2O + synchronous (pressure support ventilation, PSV) or asynchronous (pressure-controlled intermittent mandatory ventilation, PC-IMV) inspiratory assistance. ΔPes, respiratory system, lung and chest-wall mechanics were assessed with esophageal manometry and occlusions. PEEP-induced alveolar recruitment and overinflation, lung dynamic strain and tidal volume distribution were assessed with electrical impedance tomography. ResultsΔPes was not systematically different at high vs. low PEEP (PSV: median 20 [15-24] cmH2O vs. 15 [13-23], p=0.24; PC-IMV: 20 [18-23] vs. 19 [17-25], p=0.67). Similarly, respiratory system and transpulmonary driving pressure, tidal volume, lung/chest-wall mechanics and pendelluft extent were not different between study phases. High PEEP resulted in lower or higher ΔPes, respiratory system and transpulmonary driving pressure according to whether this increased or decreased respiratory system compliance, respectively (r=-0.85, p<0.001; r=-0.75, p<0.001; r=-0.80, p<0.001, respectively). PEEP-induced changes in respiratory system compliance were driven by its lung component and were dependent on the extent of PEEP-induced alveolar overinflation (r=-0.66, p=0.006). High PEEP caused variable recruitment and systematic redistribution of tidal volume towards dorsal lung regions, thereby reducing dynamic strain in ventral areas (PSV: 0.49 [0.37-0.83] vs. 0.96 [0.62-1.56], p=0.003; PC-IMV: 0.65 [0.42-1.31] vs. 1.14 [0.79-1.52], p=0.002). All results were consistent during synchronous and asynchronous inspiratory assistance. InterpretationThe impact of high PEEP on ΔPes and lung stress is inter-individually variable according to different effects on respiratory system and lung compliance resulting from alveolar overinflation. High PEEP may help mitigate the risk of self-inflicted lung injury solely if it increases lung/respiratory system compliance.

Physiological effects of lung-protective ventilation in patients with lung fibrosis and usual interstitial pneumonia pattern versus primary ARDS: a matched-control study

BackgroundAlthough patients with interstitial pneumonia pattern (ILD-UIP) and acute exacerbation (AE) leading to severe acute respiratory failure may require invasive mechanical ventilation (MV), physiological data on lung mechanics during MV are lacking. We aimed at describing the physiological effect of lung-protective ventilation in patients with AE-ILD-UIP compared with primary ARDS.MethodsPartitioned lung and chest wall mechanics were assessed in a series of AE-ILD-UIP patients matched 1:1 with primary ARDS as controls (based on BMI and PaO2/FiO2 ratio). Three PEEP levels (zero = ZEEP, 4–8 cmH2O = PEEPLOW, and titrated to achieve positive end-expiratory transpulmonary pressure PL,EE = PEEPTITRATED) were used for measurements.ResultsTen AE-ILD-UIP patients and 10 matched ARDS were included. In AE-ILD-UIP median PL,EE at ZEEP was − 4.3 [− 7.6– − 2.3] cmH2O and lung elastance (EL) 44 [40–51] cmH2O/L. At PEEPLOW, PL,EE remained negative and EL did not change (p = 0.995) versus ZEEP. At PEEPTITRATED, PL,EE increased to 0.8 [0.3–1.5] cmH2O and EL to 49 [43–59] (p = 0.004 and p < 0.001 compared to ZEEP and PEEPLOW, respectively). ΔPL decreased at PEEPLOW (p = 0.018) and increased at PEEPTITRATED (p = 0.003). In matched ARDS control PEEP titration to obtain a positive PL,EE did not result in significant changes in EL and ΔPL.ConclusionsIn mechanically ventilated AE-ILD-UIP patients, differently than in patients with primary ARDS, PEEP titrated to obtain a positive PL,EE significantly worsened lung mechanics.

Lung Volume Reduction Surgery (Clinical Cases)

Emphysema is a chronic lung disease in which the walls of the alveoli in the lungs weaken and collapse; leaving abnormally large residual spaces filled with air even when the patient exhales. The most common symptoms of emphysema are shortness of breath (dyspnea); cough; fatigue; and weight loss. Emphysema often coexists with chronic obstructive pulmonary disease. The treatment of emphysema requires a multidisciplinary approach; including education; exercise; tobacco cessation; oral and inhaled medications; oxygen therapy; and lung transplantation. Lung volume reduction surgery (LVRS) may be an option for patients who experience shortness of breath and whose pulmonary function tests show severe obstruction and enlarged lungs. The surgery aims to remove the least functional part of the lung to improve airflow; diaphragm; and chest wall mechanics; as well as alveolar gas exchange in the remaining lung. Objective — to familiarize doctors with the clinic’s experience in reducing lung volume in patients with bullous emphysema. Materials and methods. Our clinic performed the following surgical interventions to reduce lung volume: VATS resection of large (giant) lung bullae — 14 (77.7 %) cases; VATS lo­­bec­tomy — 2 (11.1 %); lobectomy through thoracotomy — 1 (5.6 %); VATS sublobar resection — 1 (5.6 %). Results and discussion. There were no fatalities. The following postoperative complications were recorded: prolonged under-expansion of the operated lung in 5 (27.7 %) cases; empyema of the residual pleural cavity with bronchial fistula in 1 (5.6 %). The overall incidence of postoperative complications was 33.3 %. Two patients with prolonged underdistension of the operated lung required reoperation (VATS revision of the pleural cavity and redilation). The patient who developed pleural empyema with a bronchial fistula underwent bronchial blockage with a satisfactory result. In all cases of LVRS; a positive clinical effect was recorded in the first 3 months after surgery. During the follow-up period of up to 2 years; only 2 (11.1 %) patients showed no clinical effect and signs of progression of chronic obstructive pulmonary disease and respiratory failure were observed. Conclusions. Lung volume reduction surgery is a method of treating bullous lung disease that allows achieving overall treatment effectiveness in the follow-up period of up to 3 months in 100 % of cases; and in the follow-up period of up to 2 years — in 89.9 %. The high rate of postoperative complications in LVRS requires a physician to carefully select patients for surgery and monitor their condition daily in the postoperative period.

Personalized Respiratory Support in ARDS: A Physiology-to-Bedside Review.

Acute respiratory distress syndrome (ARDS) is a leading cause of disability and mortality worldwide, and while no specific etiologic interventions have been shown to improve outcomes, noninvasive and invasive respiratory support strategies are life-saving interventions that allow time for lung recovery. However, the inappropriate management of these strategies, which neglects the unique features of respiratory, lung, and chest wall mechanics may result in disease progression, such as patient self-inflicted lung injury during spontaneous breathing or by ventilator-induced lung injury during invasive mechanical ventilation. ARDS characteristics are highly heterogeneous; therefore, a physiology-based approach is strongly advocated to titrate the delivery and management of respiratory support strategies to match patient characteristics and needs to limit ARDS progression. Several tools have been implemented in clinical practice to aid the clinician in identifying the ARDS sub-phenotypes based on physiological peculiarities (inspiratory effort, respiratory mechanics, and recruitability), thus allowing for the appropriate application of personalized supportive care. In this narrative review, we provide an overview of noninvasive and invasive respiratory support strategies, as well as discuss how identifying ARDS sub-phenotypes in daily practice can help clinicians to deliver personalized respiratory support and potentially improve patient outcomes.

Comparison of Changes in Chest Wall Mechanics and Respiratory Timing Between Patient-Controlled Epidural Analgesia and Intravenous Patient-Controlled Analgesia After Laparoscopic Gastrectomy: A Randomized Controlled Trial.

Upper abdominal surgery is associated with postoperative diaphragmatic dysfunction. Whether patient-controlled epidural analgesia (PCEA) is superior to intravenous patient-controlled analgesia (IV-PCA) in preventing postoperative diaphragmatic dysfunction is still unclear in laparoscopic gastric surgery. Sixteen patients undergoing laparoscopic gastrectomy randomly received either PCEA or IV-PCA. The primary outcomes were the change in chest wall mechanics and respiratory timing, measured by respiratory inductive plethysmography(Respitrace; Ambulatory Monitoring Inc., Ardsley, New York, United States) before and after surgery, and analyzed by a data acquisition system (PowerLab; ADInstruments, Dunedin, New Zealand). Inspiratory time (Ti), expiratory time (Te), total respiratory cycle time (Ttot), proportion of inspiratory time over total respiratory cycle time (Ti/Ttot), respiratory rate (RR), and abdominal contribution to tidal volume (AB/VT [%]) were calculated from the stored data. AB/VT, relative volume contribution of diaphragm to tidal breathing, represents an index of diaphragmatic function.Because the diaphragm is the main contributor to tidal volume, decreases in AB/VT indicate diaphragm dysfunction. Changes in outcomes over time between the two groups were analyzed using a linear mixed model, and two-sided p values < 0.05 were considered statistically significant. The secondary outcomes were postoperative pain score(visual analog scale (VAS)), bowel function recovery, and hospital stay duration. Postoperative AB/VT in the IV-PCA group was significantly decreased compared to preoperative levels. AB/VT in the PCEA group was significantly higher than the IV-PCA group on postoperative day (POD) 1. Change in AB/VT over time between the PCEA group and the IV-PCA group differed significantly (p = 0.01). A decrease of AB/VT during POD 1 to 3 was observed in the IV-PCA group but not in the PCEA group. As for respiratory timing, there were significant increases in RR with a reduction of Te and Ttot compared to preoperative levels on POD 1 in the PCEA group. There were significant decreases in RR and Ti/Ttot with an increase of Te and Ttot compared to preoperative levels on POD 1 in the IV-PCA group. There was a significant difference in the change of the Ttot over time between the two groups (p = 0.046). There were no significant differences in the changes of Te, Ti/Ttot, Ti, and RR over time between the two groups. There was no significant difference in VAS over time at rest and mobilization, recovery of bowel function, and hospital stay between the two groups. Continuous ropivacaine infusion with PCEA partially attenuated diaphragmatic dysfunction after laparoscopic gastrectomy, while pain relief by continuous intravenous administration of fentanyl could not attenuate diaphragmatic dysfunction. This suggests that PCEA might ameliorate postoperative diaphragmatic dysfunction after laparoscopic gastrectomy.

Respiratory Monitoring During Mechanical Ventilation: The Present and the Future.

The increased application of mechanical ventilation, the recognition of its harms and the interest in individualization raised the need for an effective monitoring. An increasing number of monitoring tools and modalities were introduced over the past 2 decades with growing insight into asynchrony, lung and chest wall mechanics, respiratory effort and drive. They should be used in a complementary rather than a standalone way. A sound strategy can guide a reduction in adverse effects like ventilator-induced lung injury, ventilator-induced diaphragm dysfunction, patient-ventilator asynchrony and helps early weaning from the ventilator. However, the diversity, complexity, lack of expertise, and associated cost make formulating the appropriate monitoring strategy a challenge for clinicians. Most often, a big amount of data is fed to the clinicians making interpretation difficult. Therefore, it is fundamental for intensivists to be aware of the principle, advantages, and limits of each tool. This analytic review includes a simplified narrative of the commonly used basic and advanced respiratory monitors along with their limits and future prospective.

Practical Aspects of Esophageal Pressure Monitoring in Patients with Acute Respiratory Distress Syndrome.

Esophageal pressure (Pes) monitoring is a minimally invasive advanced respiratory monitoring method with the potential to guide ventilation support management. Pes monitoring enables the separation of lung and chest wall mechanics and estimation of transpulmonary pressure, which is recognized as an important risk factor for lung injury during both spontaneous breathing and mechanical ventilation. Appropriate balloon positioning, calibration, and measurement techniques are important to avoid inaccurate results. Both the approach of using absolute expiratory Pes values and the approach based on tidal Pes difference have shown promising results for ventilation adjustments, with the potential to decrease the risk of ventilator-induced lung injury.

Lung volume reduction surgery—a narrative review of clinical evidence, patient selection and peri-operative care

Background and objective: Lung volume reduction surgery (LVRS) in patients with severe emphysema aims to remove the least functional part of the lungs to improve airflow, diaphragmatic and chest wall mechanics and alveolar gas exchange in the remaining lungs.

Effect of Upright and Slouched Postures on the Diaphragm Strength and Chest Expansion in Obese Young Adults – An Observational Study

Context: Obese individuals are at high risk of adopting slouched posture because of their excessive body fat distribution. Moreover, excess body fat limits the action of the respiratory muscles and restricts diaphragm mobility and rib movement. Aims: The aim of this study was to study the influence of upright versus slouched posture on respiratory muscle strength and chest expansion in obese young adults. Settings and Design: The participants included in the study were young adults of all genders between the age group of 18 and 25 years with a body mass index above 27.5. Methods and Materials: It is an observational study. Thirty participants were recruited from health-care institutions. Screening was done according to the inclusion and exclusion criteria. Diaphragm strength and chest expansion were assessed in upright sitting and slouched sitting postures. Statistical analysis used: SPSS statistical package version 23 was used to analyze the data. Normality of the baseline data was checked using Student's t-test. To summarize the data, descriptive statistics (mean and standard deviation) were employed. To discover variations in maximal inspiratory pressure (MIP) scores and chest expansion between slouched and upright sitting positions, a paired t-test analysis was performed. Results: The participants showed a lower MIP score in slouched sitting as compared to an upright sitting posture. The mean difference in the MIP scores was 20.99 mmHg (P = 0.04). Chest expansion measurements also showed a significant difference between the two sitting postures. Conclusions: The lower maximal inspiratory pressure and chest expansion measures observed in this study indicate that in obese individuals, slouched sitting posture can adversely affect the diaphragm strength and the chest wall mechanics during breathing.

Volumes da parede torácica, mobilidade diafragmática e capacidade funcional em pacientes com mucopolissacaridoses

Purpose We investigated respiratory muscle strength, diaphragm mobility, lung function, functional capacity, quality of life, body composition, breathing pattern, and chest wall (V T,CW) and compartmental volumes of Mucopolysaccharidosis (MPS) patients and compared these variables with matched healthy individuals. Methods A cross-sectional study with data analyzed separately according to age group. A total of 68 individuals (34 MPS and 34 matched-healthy subjects) were included. Six-minute walking test assessed functional capacity and ultrasound assessed diaphragm mobility during quiet spontaneous breathing (QB). Optoelectronic plethysmography assessed V T,CW and breathing pattern during QB in two different positions: seated and supine (45° trunk inclination). Results Body composition, lung function, respiratory muscle strength, and functional capacity were reduced in MPS (all p < 0.01). Diaphragm mobility was only reduced in adolescents (p = 0.01) and correlated with body composition and breathing pattern. Upper chest wall compartmental volumes were significantly lower in MPS, while abdominal volume only differed significantly in adolescents. Percentage contribution (%) of upper ribcage compartments to tidal volume was reduced in MPS children, whereas %AB was significantly increased compared with healthy subjects. Conclusion Lung function, respiratory muscle strength, functional capacity, diaphragm mobility, and quality of life are reduced in MPS compared with matched healthy subjects. V T,CW was mainly reduced due to pulmonary and abdominal ribcage impairment. Implications for Rehabilitation Reduction in respiratory muscle strength, functional capacity, diaphragm excursion and low lung volumes were found in individuals with Mucopolysaccharidoses (MPS). Chest wall volumes and the upper chest wall compartmental volumes during quiet spontaneous breathing are reduced in MPS. Assessment and monitoring of the respiratory system for individuals with MPS should be performed periodically through standardized assessments to enable identification of changes and early intervention by rehabilitation protocols. This study may provide the necessary basis for carrying out respiratoty rehabilitation protocols that can improving chest wall mechanics with breathing exercise in this group.

Chest wall mechanics during mechanical chest compression and its relationship to CPR-related injuries and survival

AimTo determine compression force variation (CFV) during mechanical cardiopulmonary resuscitation (CPR) and its relationship with CPR-related injuries and survival. MethodsAdult non-traumatic OHCA patients who had been treated with mechanical CPR were evaluated for CPR-related injuries using chest X-rays, thoracic computed tomography or autopsy. The CFV exerted by the LUCAS 2 device was calculated as the difference between the maximum and the minimum force values and was categorised into three different groups (high positive CFV ≥ 95 newton (N), high negative CFV ≤ -95 N, and low variation for intermediate CFV). The CFV was correlated with the CPR injuries findings and survival data. ResultsFifty-two patients were included. The median (IQR) age was 57 (49–66) years, and 13 (25%) cases survived until hospital admission. High positive CFV was found in 21 (40.4%) patients, high negative CFV in 9 (17.3%) and a low CFV in 22 (42.3%). The median (IQR) number of rib fractures was higher in the high positive and negative CFV groups compared with the low CFV group [7(1–9) and 9 (4–11) vs 0 (0–6) (p = 0.021)]. More bilateral fracture cases were found in the high positive and negative CFV groups [16 (76.2%) and 6 (66.7%) vs 6 (27.3%) (p = 0.004)]. In the younger half of the sample more patients survived until hospital admission in the low CFV group compared with the high CFV groups [5 (41.7%) vs 1 (7.1%) (p = 0.037)]. ConclusionsHigh CFV was associated with ribcage injuries. In the younger patients low CFV was associated with survival until hospital admission.

Long term outcomes following rib fracture fixation in patients with major chest trauma

Severe chest injuries are associated with significant morbidity and mortality. Surgical rib fixation has become a more commonplace procedure to improve chest wall mechanics, pain, and function. The aim of this study was to characterise the epidemiology and long-term functional outcomes of chest trauma patients who underwent rib fixation in a major trauma centre (MTC). This was a retrospective review (2014-19) of all adult patients with significant chest injury who had rib fixation surgery following blunt trauma to the chest. The primary outcome was functional recovery after hospital discharge, and secondary outcomes included length of intensive care unit (ICU) and hospital stay, maximum organ support, tracheostomy insertion, ventilator days. 60 patients underwent rib fixation. Patients were mainly male (82%) with median age 52 (range 24-83) years, injury severity score (ISS) of 29 (21-38), 10 (4-19) broken ribs, and flail segment in 90% of patients. Forty-six patients (77%) had a good outcome (GOSE grade 6-8). Patients in the poor outcome group (23%; GOSE 1-5) tended to be older [55 (39-83) years vs. 51 (24-78); p=0.05] and had longer length of hospital stay [42 (19-82) days vs. 24 (7-90); p<0.01]. Injury severity, rate of mechanical ventilation or organ dysfunction did not affect long term outcome. Nineteen patients (32%) were not mechanically ventilated. Rib fixation was associated with good long-term outcomes in severely injured patients. Age was the only predictor of long-term outcome. The results suggest that rib fixation be considered in patients with severe chest injuries and may also benefit those who are not mechanically ventilated but are at risk of deterioration.

Lung and chest wall mechanical properties in metformin-treated and untreated models of type 2 diabetes

The adverse respiratory consequences of type 2 diabetes mellitus (T2DM) may reflect compromised lung function and/or alterations of the chest wall because of skeletal muscle stiffening. We assessed the separate contributions of these compartments to respiratory complications in diabetes and explored the effects of metformin on respiratory abnormalities. Experiments were performed in untreated rats (control, n = 7), high-fat diet-fed rats receiving streptozotocin (T2DM, n = 7), and metformin-treated diabetic rats (MET, n = 6). Newtonian resistance, tissue damping, and elastance were separately assessed for lung and chest wall components by measuring the esophageal pressure during forced oscillations at low (0 cmH2O), medium (3 cmH2O), and high positive end-expiratory pressure (PEEP) (6 cmH2O). Tissue hysteresivity was calculated as damping/elastance. Blood gas parameters were used to assess gas exchange, and lung histology was performed to characterize collagen expression. T2DM at low PEEP compromised airway and lung tissue mechanics in association with gas-exchange defects and collagen overexpression. Abnormal chest wall mechanics in T2DM was indicated only by decreased tissue hysteresivity. No difference in lung or chest wall mechanics, gas exchange, or lung histology was observed between the MET and control groups. These findings suggest the primary involvement of the pulmonary system in the respiratory consequences of T2DM, with chest wall properties only disturbed by a shift toward the dominance of elastic forces at low PEEP. The adequacy of metformin to treat the adverse respiratory consequences of diabetes was also revealed, in addition to its well-established beneficial effects on other organs.NEW & NOTEWORTHY The present study examined the contributions of the lungs and chest wall to respiratory complications in a rat model of diabetes and clarified the effects of metformin on these changes. At low positive end-expiratory pressure, type 2 diabetes was linked to dysfunctional airway and lung tissue mechanics in relation with gas-exchange defects and collagen overexpression, whereas decreased tissue hysteresivity was manifested in the chest wall abnormalities. Metformin treated all adverse respiratory consequences of diabetes.