Prone-position decreases airway closure in a patient with ARDS undergoing venovenous extracorporeal membrane oxygenation.

Airway closure is a interruption of communication between larger and smaller airways. The presence of airway closure during mechanical ventilation may lead to the overestimation of driving pressure (DP), introducing errors in the assessment of respiratory mechanics and in positive end-expiratory pressure (PEEP) setting on the ventilator. Patients with severe acute respiratory distress syndrome (ARDS) may exhibit the airway closure phenomenon, which can be easily diagnosed with a low-flow inflation. Prone positioning is a therapeutic manoeuver proven to reduce mortality in ARDS patients, and has been widely implemented also in patients requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). To date, the impact of prone positioning on changes in airway closure has not been described. We present an image analysis of the pressure waveform during volume-controlled ventilation and low-flow inflations before and after prone positioning in an ARDS patient on VV ECMO. A high airway opening pressure level (23 cmH2O) was detected in the supine position during tidal ventilation. Airway closure was confirmed by using a low-flow inflation. Prone positioning significantly attenuated airway closure, with the airway opening pressure decreasing to 13 cmH2O. After re-supination, airway closure was lower as compared with supine position at baseline (17 cmH2O). Prone positioning reduced airway closure in an ARDS patient on VV ECMO support.

Giani M ，Restivo A ，Raimondi Cominesi D ，Fracchia R ，Pozzi M ，Del Sorbo L ，Foti G ，Brochard L ，Rezoagli E ... -  《-》

Positive end-expiratory pressure management in patients with severe ARDS: implications of prone positioning and extracorporeal membrane oxygenation.

The optimal strategy for positive end-expiratory pressure (PEEP) titration in the management of severe acute respiratory distress syndrome (ARDS) patients remains unclear. Current guidelines emphasize the importance of a careful risk-benefit assessment for PEEP titration in terms of cardiopulmonary function in these patients. Over the last few decades, the primary goal of PEEP usage has shifted from merely improving oxygenation to emphasizing lung protection, with a growing focus on the individual pattern of lung injury, lung and chest wall mechanics, and the hemodynamic consequences of PEEP. In moderate-to-severe ARDS patients, prone positioning (PP) is recommended as part of a lung protective ventilation strategy to reduce mortality. However, the physiologic changes in respiratory mechanics and hemodynamics during PP may require careful re-assessment of the ventilation strategy, including PEEP. For the most severe ARDS patients with refractory gas exchange impairment, where lung protective ventilation is not possible, veno-venous extracorporeal membrane oxygenation (V-V ECMO) facilitates gas exchange and allows for a "lung rest" strategy using "ultraprotective" ventilation. Consequently, the importance of lung recruitment to improve oxygenation and homogenize ventilation with adequate PEEP may differ in severe ARDS patients treated with V-V ECMO compared to those managed conservatively. This review discusses PEEP management in severe ARDS patients and the implications of management with PP or V-V ECMO with respect to respiratory mechanics and hemodynamic function.

Boesing C ，Rocco PRM ，Luecke T ，Krebs J ... -  《CRITICAL CARE》

The impact of a lung-protective ventilation mode using transpulmonary driving pressure titrated positive end-expiratory pressure on the prognosis of patients with acute respiratory distress syndrome.

This study aimed to assess the impact of a lung-protective ventilation strategy utilizing transpulmonary driving pressure titrated positive end-expiratory pressure (PEEP) on the prognosis [mechanical ventilation duration, hospital stay, 28-day mortality rate and incidence of ventilator-associated pneumonia (VAP), survival outcome] of patients with Acute Respiratory Distress Syndrome (ARDS). A total of 105 ARDS patients were randomly assigned to either the control group (n = 51) or the study group (n = 53). The control group received PEEP titration based on tidal volume [A tidal volume of 6 mL/kg, flow rate of 30-60 L/min, frequency of 16-20 breaths/min, constant flow rate, inspiratory-to-expiratory ratio of 1:1 to 1:1.5, and a plateau pressure ≤ 30-35 cmH2O. PEEP was adjusted to maintain oxygen saturation (SaO2) at or above 90%, taking into account blood pressure], while the study group received PEEP titration based on transpulmonary driving pressure (Esophageal pressure was measured as a surrogate for pleural pressure using an esophageal pressure measurement catheter connected to the ventilator. Tidal volume and PEEP were adjusted based on the observed end-inspiratory and end-expiratory transpulmonary pressures, aiming to maintain a transpulmonary driving pressure below 15 cmH2O during mechanical ventilation. Adjustments were made 2-4 times per day). Statistical analysis and comparison were conducted on lung function indicators [oxygenation index (OI), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2)] as well as other measures such as heart rate, mean arterial pressure, and central venous pressure in two groups of patients after 48 h of mechanical ventilation. The 28-day mortality rate, duration of mechanical ventilation, length of hospital stay, and ventilator-associated pneumonia (VAP) incidence were compared between the two groups. A 60-day follow-up was performed to record the survival status of the patients. In the control group, the mean age was (55.55 ± 10.51) years, with 33 females and 18 males. The pre-ICU hospital stay was (32.56 ± 9.89) hours. The mean Acute Physiology and Chronic Health Evaluation (APACHE) II score was (19.08 ± 4.67), and the mean Murray Acute Lung Injury score was (4.31 ± 0.94). In the study group, the mean age was (57.33 ± 12.21) years, with 29 females and 25 males. The pre-ICU hospital stay was (33.42 ± 10.75) hours. The mean APACHE II score was (20.23 ± 5.00), and the mean Murray Acute Lung Injury score was (4.45 ± 0.88). They presented a homogeneous profile (all P > 0.05). Following intervention, significant improvements were observed in PaO2 and OI compared to pre-intervention values. The study group exhibited significantly higher PaO2 and OI compared to the control group, with statistically significant differences (all P < 0.05). After intervention, the study group exhibited a significant increase in PaCO2 (43.69 ± 6.71 mmHg) compared to pre-intervention levels (34.19 ± 5.39 mmHg). The study group's PaCO2 was higher than the control group (42.15 ± 7.25 mmHg), but the difference was not statistically significant (P > 0.05). There were no significant differences in hemodynamic indicators between the two groups post-intervention (all P > 0.05). The study group demonstrated significantly shorter mechanical ventilation duration and hospital stay, while 28-day mortality rate and incidence of ventilator-associated pneumonia (VAP) showed no significant differences. Kaplan-Meier survival analysis revealed a significantly better survival outcome in the study group at the 60-day follow-up (HR = 0.565, 95% CI: 0.320-0.999). Lung-protective mechanical ventilation using transpulmonary driving pressure titrated PEEP effectively improves lung function, reduces mechanical ventilation duration and hospital stay, and enhances survival outcomes in patients with ARDS. However, further study is needed to facilitate the wider adoption of this approach.

Sun J ，Gao J ，Huang GD ，Zhu XG ，Yang YP ，Zhong WX ，Geng L ，Zhou MJ ，Xu Q ，Feng QM ，Zhao G ... -  《-》

Far Posterior Approach for Rib Fracture Fixation: Surgical Technique and Tips.

The present video article describes the far posterior or paraspinal approach to posterior rib fractures. This approach is utilized to optimize visualization intraoperatively in cases of far-posterior rib fractures. This technique is also muscle-sparing, and muscle-sparing posterolateral, axillary, and anterior approaches have been shown to return up to 95% of periscapular strength by 6 months postoperatively1. Like most fractures, the skin incision depends on the fracture position. The vertical incision is made either just medial to a line equidistant between the palpable spinous processes and medial scapular border or directly centered over the fracture line in this region. The incision and superficial dissection must be extended cranially and caudally, approximately 1 or 2 rib levels past the planned levels of instrumentation, in order to allow muscle elevation and soft-tissue retraction. Superficial dissection reveals the trapezius muscle, with its fibers coursing from inferomedial to superolateral caudal to the scapular spine, and generally coursing transversely above this level. The trapezius is split in line with its fibers (or elevated proximally at the caudal-most surface), and the underlying layer will depend on the location of the incision. The rhomboid minor muscle overlies ribs 1 and 2, the rhomboid major muscle overlies ribs 3 to 7, and the latissimus dorsi overlies the remaining rib levels. To avoid muscle transection, the underlying muscle is also split in line with its fibers. Next, the thoracolumbar fascia is encountered and sharply incised, revealing the erector spinae muscles, which comprise the spinalis thoracis, longissimus thoracis, and iliocostalis thoracis muscles. These muscles and their tendons must be sharply elevated from lateral to midline; electrocautery is useful for this because there is a robust blood supply in this region. Medially, while retracting the paraspinal musculature, visualization with this approach can extend to the head and neck of the rib, and even to the spine. Following deep dissection, the fractures are now visualized. During fracture reduction, it is critical to assess reduction of both the costovertebral joint and the costotransverse joint. With fractures closer to the spine, it is recommended to have at least 2 cm between the rib head and tubercle in order to allow 2 plate holes to be positioned on the neck of the rib; if comminution exists and plating onto the transverse process is needed, several screws are required here for stability as well. For appropriate stability if plating onto the spine is not required, a minimum of 3 locking screws on each side of the fracture are recommended. Contouring of the plates to match the curvature of the rib and to allow for proper apposition may be required with posterior rib fractures. Screws must be placed perpendicular to the rib surface. Following operative stabilization of the rib fractures, a layered closure is performed, and a soft dressing is applied. Nonoperative alternatives include non-opioid and opioid medications as well as corticosteroid injections for pain control. Supportive mechanical ventilation and physiotherapy breathing exercises can also be implemented as needed. Operative alternatives include open reduction and internal fixation utilizing conventional locking plates and screws. Rib fractures are often treated nonoperatively when nondisplaced because of the surrounding soft-tissue support2,3. According to Chest Wall Injury Society guidelines, contraindications to surgical fixation of rib fractures include patients requiring ongoing resuscitation; rib fractures involving ribs 1, 2, 11, or 12, which are relative contraindications; severe traumatic brain injury; and acute myocardial infarction. Patient age of <18 years is also a relative contraindication for the operative treatment of rib fractures. The current literature does not recommend surgical fixation in this age group because these fractures typically heal as the patient ages; however, fracture-dislocations may require the use of instrumentation to prevent displacement. Currently, the U.S. Food and Drug Administration does not approve most plating systems for patients <18 years old4. In certain cases, including those with substantial displacement, persistent respiratory distress, pain, or fracture nonunion, stabilization with open reduction and internal fixation may be appropriate5-7. In cases of flail chest injuries, surgery is often indicated6. Flail chest injuries have been noted in the literature to have an incidence of approximately 150 cases per 100,000 injuries and have been shown to carry a mortality rate of up to 33%8,9. Surgical treatment of rib fractures has been shown to be associated with a decreased hospital length of stay and mortality rate in patients with major trauma1. Expected outcomes of this procedure include low complication rates, decreased hospital and intensive care unit length of stay, and reduced mechanical ventilation time10,11. However, as with any procedure, there are also risks involved, including iatrogenic lung injury from long screws or an aortic or inferior vena cava injury with aggressive manipulation of displaced fractured fragments, especially on the left side of the body. During open reduction, there is also a risk of injuring the neurovascular bundle. Tanaka et al. demonstrated a significant reduction in the rate of postoperative pneumonia in their operative group (22%) compared with their nonoperative group (90%)12. Schuette et al. demonstrated a 23% rate of postoperative pneumonia, 0% mortality at 1 year, an average of 6.2 days in the intensive care unit, an average total hospital length of stay of 17.3 days, and an average total ventilator time of 4 days in the operative group10. Prins et al. reported a significantly lower incidence of pneumonia in operative (24%) versus nonoperative patients (47.3%; p = 0.033), as well as a significantly lower 30-day mortality rate (0% versus 17.7%; p = 0.018)3. This procedure utilizes a muscle-sparing technique, which has demonstrated successful results in the literature on the use of the posterolateral, axillary, and anterior approaches, returning up to 95% of periscapular strength, compared with the uninjured shoulder, by 6 months postoperatively1. The use of a muscle-sparing technique with the far-posterior approach represents a topic that requires further study in order to compare the results with the successful results previously shown with other approaches. The ipsilateral extremity can be prepared into the field to allow its intraoperative manipulation in order to achieve scapulothoracic motion and improved subscapular access.For costovertebral fracture-dislocations, the vertical incision line is made just medial to a line equidistant between the palpable spinous processes and medial scapular border.Lateral decubitus positioning can be utilized to allow for simultaneous access to fractures that extend more laterally and warrant a posterolateral approach; however, it is generally more difficult to access the fracture sites near the spine with this approach.This muscle-sparing technique is recommended to optimize postoperative periscapular strength, as previously demonstrated with other approaches.Incision and superficial dissection must be extended cranially and caudally approximately 1 or 2 rib levels past the planned levels of instrumentation in order to allow muscle elevation and soft-tissue retraction.To avoid muscle transection during surgical dissection, the underlying muscle is split in line with its fibers.During deep dissection, it can be difficult to delineate underlying muscles because these muscles have fibers that do not run in line with the trapezius, and some, like the rhomboid major, run nearly perpendicular to it.Electrocautery is useful while elevating the erector spinae muscles and tendons, as there is a robust blood supply in this region.The erector spinae muscle complex is relatively tight and adherent to the underlying ribs, which may make it difficult to achieve adequate visualization; therefore, at least 3 rib levels must be elevated to access a rib for reduction and instrumentation.Although internal rotation deformities are more common in this region, any external displacement of a fracture can lead to a muscle injury that can be utilized for access.During fracture reduction, it is critical to assess reduction of both the costovertebral joint and the costotransverse joint.Special attention must be given to contouring the implants because there are not any commercially available precontoured implants for this region at this time, and plating onto the spine remains an off-label use of any currently available implant.For the more challenging fracture patterns, the use of a right-angled power drill and screwdriver is recommended.Generally, the incision is utilized as previously described to provide access as far medial as the transverse process if needed. However, in cases in which this approach does not allow proper visualization with rib fracture-dislocations involving the posterior ribs or spine, a midline spinal incision can be utilized while working in combination with a spine surgeon.With fractures closer to the spine, it is recommended to have at least 2 cm between the rib head and tubercle in order to allow 2 plate holes to be positioned on the neck of the rib.If comminution exists and plating onto the transverse process is needed, several screws are required for stability.When measuring the length of screws to be placed in the transverse process, preoperative CT scans can be utilized. CT = computed tomographyCWIS = Chest Wall Injury SocietyIVC = inferior vena cava.

Manes TJ ，DeGenova DT ，Taylor BC ，Patel JN ... -  《-》

Prone position ventilation-induced oxygenation improvement as a valuable predictor of survival in patients with acute respiratory distress syndrome: a retrospective observational study.

In patients with severe acute respiratory distress syndrome (ARDS), prolonged and inappropriate use of prone position ventilation (PPV) is a known risk factor for mortality. Hence, it is critical to monitor patients' response to PPV and accurately differentiate responders from non-responders at an early stage. The study aimed to investigate the relationship between oxygenation improvement after three rounds of PPV and survival rate in patients with pulmonary ARDS. Additionally, we sought to identify the earliest turning point for escalation from PPV to extracorporeal membrane oxygenation. We performed a retrospective observational study from 2015 to 2023. We included adult patients who received invasive mechanical ventilation, underwent at least three periods of at least 6 h of PPV after admission to the Intensive Care Unit, and meet the ARDS criteria. The study collected data on each PPV session, including changes in PaCO2, PaO2, pH, FiO2, PaO2:FiO2 ratio, and clinical outcomes. A total of 104 patients were enrolled in the study. The change in PaCO2 from baseline to the third PPV session (P3) had the highest area under the receiver operating characteristic curve (AUC) of 0.70 (95% CI 0.60-0.80; p < 0.001) for predicting hospital mortality, with an optimal cut-off point of 3.15 (sensitivity 75.9%, specificity 56.0%). The percentage change in PaO2:FiO2 ratio from baseline to P3 also had significant AUC of 0.71 (95% CI 0.61-0.81; p < 0.001) for predicting hospital mortality, with an optimal cut-off value of 99.465 (sensitivity 79.6%, specificity 62.0%). PaCO2 responders were defined as those with an increase in PaCO2 of ≤ 3.15% from baseline to P3, while PaO2:FiO2 responders were defined as those with an increase in PaO2:FiO2 ratio of ≥ 99.465% from baseline to P3. In the multivariable Cox analysis, PaO2:FiO2 responders had a significantly lower 60-day mortality risk (hazard ratio 0.369; 95% CI 0.171-0.798; p = 0.011). The percentage change in PaO2:FiO2 ratio from baseline to P3 was a significant predictor of outcomes. The model fit and prediction accuracy were improved by including the variable of PaCO2 responders.

Liang H ，Deng Q ，Ye W ，Jiang Z ，Zhang B ，Zhang J ，Jiang M ，Xu Y ... -  《BMC Pulmonary Medicine》