Whole lung lavage decreases physiological dead space in patients with pulmonary alveolar proteinosis: two case reports.

BACKGROUND: Pulmonary alveolar proteinosis (PAP) is a rare disease characterized by progressive accumulation of the alveolar surfactant. Whole lung lavage (WLL) using a high volume of warmed saline remains the standard therapy. However, no established bedside monitoring tool can evaluate the physiological effect of WLL in the perioperative period. Indirect calorimetry, which is generally used to measure resting energy expenditure, can detect carbon dioxide (CO2) production and mixed-expired partial pressure of CO2 breath by breath. In this physiological study, we calculated CO2 elimination per breath (VTCO2,br) and Enghoff's dead space using indirect calorimetry and measured the extravascular lung water index to reveal the effect of WLL. CASE PRESENTATION: We measured VTCO2,br, Enghoff's dead space, and the extravascular lung water and cardiac indices before and after WLL to assess the reduction in shunt by washing out the surfactant. A total of four WLLs were performed in two PAP patients. The first case involved an Asian 62-year-old man who presented with a 3-month history of dyspnea on exertion. The second case involved an Asian 48-year-old woman with no symptoms. VTCO2,br increased, and the Enghoff's dead space decreased at 12 h following WLL. An increase in the extravascular lung water was detected immediately following WLL, leading to a transient increase in Enghoff's dead space. CONCLUSION: WLL can increase efficient alveolar ventilation by washing out the accumulated surfactant. However, the lavage fluid may be absorbed into the lung tissues immediately after WLL and result in an increase in the extravascular lung water.

Clinical Implications of Determining Individualized Positive End-Expiratory Pressure Using Electrical Impedance Tomography in Post-Cardiac Surgery Patients: A Prospective, Non-Randomized Interventional Study.

Optimal positive end-expiratory pressure (PEEP) can induce sustained lung function improvement. This prospective, non-randomized interventional study aimed to investigate the effect of individualized PEEP determined using electrical impedance tomography (EIT) in post-cardiac surgery patients (n = 35). Decremental PEEP trials were performed from 20 to 4 cmH2O in steps of 2 cmH2O, guided by EIT. PEEP levels preventing ventilation loss in dependent lung regions (PEEPONLINE) were set. Ventilation distributions and oxygenation before the PEEP trial, and 5 min and 1 h after the PEEPONLINE setting were examined. Furthermore, we analyzed the saved impedance data offline to determine the PEEP levels that provided the best compromise between overdistended and collapsed lung (PEEPODCL). Ventilation distributions of dependent regions increased at 5 min after the PEEPONLINE setting compared with those before the PEEP trial (mean ± standard deviation, 41.3 ± 8.5% vs. 49.1 ± 9.3%; p < 0.001), and were maintained at 1 h thereafter (48.7 ± 9.4%, p < 0.001). Oxygenation also showed sustained improvement. Rescue oxygen therapy (high-flow nasal cannula, noninvasive ventilation) after extubation was less frequent in patients with PEEPONLINE ≥ PEEPODCL than in those with PEEPONLINE < PEEPODCL (1/19 vs. 6/16; p = 0.018). EIT-guided individualized PEEP stabilized the improvement in ventilation distribution and oxygenation. Individual PEEP varies with EIT measures, and may differentially affect oxygenation after cardiac surgery.

A novel definition and treatment of hyperinflammation in COVID-19 based on purinergic signalling.

Hyperinflammation plays an important role in severe and critical COVID-19. Using inconsistent criteria, many researchers define hyperinflammation as a form of very severe inflammation with cytokine storm. Therefore, COVID-19 patients are treated with anti-inflammatory drugs. These drugs appear to be less efficacious than expected and are sometimes accompanied by serious adverse effects. SARS-CoV-2 promotes cellular ATP release. Increased levels of extracellular ATP activate the purinergic receptors of the immune cells initiating the physiologic pro-inflammatory immune response. Persisting viral infection drives the ATP release even further leading to the activation of the P2X7 purinergic receptors (P2X7Rs) and a severe yet physiologic inflammation. Disease progression promotes prolonged vigorous activation of the P2X7R causing cell death and uncontrolled ATP release leading to cytokine storm and desensitisation of all other purinergic receptors of the immune cells. This results in immune paralysis with co-infections or secondary infections. We refer to this pathologic condition as hyperinflammation. The readily available and affordable P2X7R antagonist lidocaine can abrogate hyperinflammation and restore the normal immune function. The issue is that the half-maximal effective concentration for P2X7R inhibition of lidocaine is much higher than the maximal tolerable plasma concentration where adverse effects start to develop. To overcome this, we selectively inhibit the P2X7Rs of the immune cells of the lymphatic system inducing clonal expansion of Tregs in local lymph nodes. Subsequently, these Tregs migrate throughout the body exerting anti-inflammatory activities suppressing systemic and (distant) local hyperinflammation. We illustrate this with six critically ill COVID-19 patients treated with lidocaine.

Personalisation of Therapies in COVID-19 Associated Acute Respiratory Distress Syndrome, Using Electrical Impedance Tomography.

INTRODUCTION: Each patient suffering from severe coronavirus COVID-19-associated acute respiratory distress syndrome (ARDS), requiring mechanical ventilation, shows different lung mechanics and disease evolution. Therefore, lung protective strategies should be personalised for the individual patient. CASE PRESENTATION: A 64-year-old male patient was intubated ten days after the symptoms of COVID-19 infection presented. He was placed in the prone position for sixteen hours, resulting in a marked improvement in oxygenation. However, after being returned to the supine position, his SpO2 rapidly dropped from 98% to 91%, and electrical impedance tomography showed less ventilation at the dorsal region and a ventral shift of ventilation distribution. An incremental and decremental PEEP trial under electrical impedance tomography monitoring was carried out, confirming that the dependent lung regions were recruited with increased pressures and homogenous ventilation distribution could be provided with 14 cmH2O of PEEP. The optimal settings were reassessed next day after returning from the second session of the prone position. After four prone position-sessions in five days, oxygenation was stabilised and eventually the patient was discharged. CONCLUSIONS: Patients with COVID-19 associated ARDS require individualised ventilation support depending on the stage of their disease. Daily PEEP trial monitored by electrical impedance tomography can provide important information to tailor the respiratory therapies.

Extracorporeal Membrane Oxygenation for Secondary Organizing Pneumonia after Severe SARS-CoV-2 Infection: A Case Report.

(Background) COVID-19 is caused by SARS-CoV-2 infection and may result in unfavorable outcomes. A recent large-scale study showed that treatment with dexamethasone leads to favorable outcomes in patients with severe COVID-19, and the use of extracorporeal membrane oxygenation (ECMO) has also been shown to improve outcomes. Recently, secondary organizing pneumonia (SOP) has been reported after SARS-CoV-2 infection, but the diagnostic and treatment strategies are still unclear. (Case presentation) Here, we report a patient with severe COVID-19 who developed SOP even after the use of dexamethasone, for whom the introduction of ECMO on the 19th day after hospitalization led to a favorable outcome. (Conclusions) Life-threatening SOP may evolve even after the use of dexamethasone, and the late-phase introduction of ECMO may save such patients with COVID-19.

Roles of Early Mobilization Program in Preventing Muscle Weakness and Decreasing Psychiatric Disorders in Patients with Coronavirus Disease 2019 Pneumonia: A Retrospective Observational Cohort Study.

Although many coronavirus 2019 patients have experienced persistent symptoms and a long-term decline in quality of life after discharge, the details of these persistent symptoms and the effect of early rehabilitation are still unclear. We conducted a single-center, retrospective observational study to investigate the prevalence of persistent symptoms three months after discharge from the intensive care unit by checking the medical records. All patients received an early mobilization program. Four out of 13 patients (31%) had postintensive care syndrome. No patients had muscle weakness, and 11 patients (85%) returned to their previous work. However, psychiatric disorder, such as anxiety (23%) and posttraumatic stress disorder (15%), were observed. Eleven patients claimed persistent symptoms, including fatigue and numbness in the extremities. Our results suggest that the implementation of an early rehabilitation program plays some role in preventing muscle weakness and that decreasing psychiatric disorders should be a next target of patient care in the intensive care unit.

Roles of Electrical Impedance Tomography in Determining a Lung Protective Strategy for Acute Respiratory Distress Syndrome in the Era of Coronavirus Disease 2019.

Electrical impedance tomography (EIT) is noninvasive and can be used at the bedside for real-time evaluation to identify ventilation distribution of infected lungs. This review briefly describes the basic principle of EIT and summarizes the latest findings on its potential contribution to lung protective strategies in coronavirus disease 2019 patients. Additionally, experimental approaches for detecting the distribution of pulmonary blood flow in coronavirus disease 2019 patients are presented. The findings underscore the role of EIT in determining lung protective strategies for coronavirus disease 2019-associated acute respiratory distress syndrome.

Positive End-expiratory Pressure and Distribution of Ventilation in Pneumoperitoneum Combined with Steep Trendelenburg Position.

BACKGROUND: Pneumoperitoneum and a steep Trendelenburg position during robot-assisted laparoscopic prostatectomy have been demonstrated to promote a cranial shift of the diaphragm and the formation of atelectasis in the dorsal parts of the lungs. However, neither an impact of higher positive end-expiratory pressure (PEEP) on preserving the ventilation in the dorsal region nor its physiologic effects have been fully examined. The authors hypothesized that PEEP of 15 cm H2O during robot-assisted laparoscopic prostatectomy might maintain ventilation in the dorsal parts and thus improve lung mechanics. METHODS: In this randomized controlled study, 48 patients undergoing robot-assisted laparoscopic prostatectomy were included in the analysis. Patients were assigned to the conventional PEEP (5 cm H2O) group or the high PEEP (15 cm H2O) group. Regional ventilation was monitored using electrical impedance tomography before and after the establishment of pneumoperitoneum and 20° Trendelenburg position during the surgery. The primary endpoint was the regional ventilation in the dorsal parts of the lungs while the secondary endpoints were lung mechanics and postoperative lung function. RESULTS: Compared to that in the conventional PEEP group, the fraction of regional ventilation in the most dorsal region was significantly higher in the high PEEP group during pneumoperitoneum and Trendelenburg position (mean values at 20 min after taking Trendelenburg position: conventional PEEP, 5.5 ± 3.9%; high PEEP, 9.9 ± 4.7%; difference, -4.5%; 95% CI, -7.4 to -1.6%; P = 0.004). Concurrently, lower driving pressure (conventional PEEP, 14.9 ± 2.5 cm H2O; high PEEP, 11.5 ± 2.8 cm H2O; P < 0.001), higher lung dynamic compliance, and better oxygenation were demonstrated in the high PEEP group. Postoperative lung function did not differ between the groups. CONCLUSIONS: Application of a PEEP of 15 cm H2O resulted in more homogeneous ventilation and favorable physiologic effects during robot-assisted laparoscopic prostatectomy but did not improve postoperative lung function.

Clinical implication of monitoring regional ventilation using electrical impedance tomography.

Mechanical ventilation can initiate ventilator-associated lung injury (VALI) and contribute to the development of multiple organ dysfunction. Although a lung protective strategy limiting both tidal volume and plateau pressure reduces VALI, uneven intrapulmonary gas distribution is still capable of increasing regional stress and strain, especially in non-homogeneous lungs, such as during acute respiratory distress syndrome. Real-time monitoring of regional ventilation may prevent inhomogeneous ventilation, leading to a reduction in VALI. Electrical impedance tomography (EIT) is a technique performed at the patient's bedside. It is noninvasive and radiation-free and provides dynamic tidal images of gas distribution. Studies have reported that EIT provides useful information both in animal and clinical studies during mechanical ventilation. EIT has been shown to be useful during lung recruitment, titration of positive end-expiratory pressure, lung volume estimation, and evaluation of homogeneity of gas distribution in a single EIT measure or in combination with multiple EIT measures. EIT-guided mechanical ventilation preserved the alveolar architecture and maintained oxygenation and lung mechanics better than low-tidal volume ventilation in animal models. However, careful assessment is required for data analysis owing to the limited understanding of the results of EIT interpretation. Previous studies indicate monitoring regional ventilation by EIT is feasible in the intensive care setting and has potential to lead to lung protective ventilation. Further clinical studies are warranted to evaluate whether monitoring of regional ventilation using EIT can shorten the duration of ventilation or improve mortality in patients with acute respiratory distress syndrome.

Biphasic Cuirass Ventilation During Anesthesia for Tracheobronchial Stent Insertion or Removal by a Rigid Bronchoscope: A Case Report.

Airway management and ventilation during a tracheobronchial stenting procedure are challenging given that mandatory positive pressure ventilation cannot be fully achieved while using a rigid bronchoscope due to leakage from the scope tip. Biphasic cuirass ventilation is a negative pressure ventilation method using an external cuirass fitted to the anterior chest, which could assist in spontaneous breathing and ventilation support. We report 3 successful anesthesia cases in which we could maintain adequate ventilation and oxygenation, supported by biphasic cuirass ventilation, in patients undergoing tracheobronchial stent placement or removal procedures using rigid bronchoscopy.

Excessive Extracellular ATP Desensitizes P2Y2 and P2X4 ATP Receptors Provoking Surfactant Impairment Ending in Ventilation-Induced Lung Injury.

Stretching the alveolar epithelial type I (AT I) cells controls the intercellular signaling for the exocytosis of surfactant by the AT II cells through the extracellular release of adenosine triphosphate (ATP) (purinergic signaling). Extracellular ATP is cleared by extracellular ATPases, maintaining its homeostasis and enabling the lung to adapt the exocytosis of surfactant to the demand. Vigorous deformation of the AT I cells by high mechanical power ventilation causes a massive release of extracellular ATP beyond the clearance capacity of the extracellular ATPases. When extracellular ATP reaches levels >100 μM, the ATP receptors of the AT II cells become desensitized and surfactant impairment is initiated. The resulting alteration in viscoelastic properties and in alveolar opening and collapse time-constants leads to alveolar collapse and the redistribution of inspired air from the alveoli to the alveolar ducts, which become pathologically dilated. The collapsed alveoli connected to these dilated alveolar ducts are subject to a massive strain, exacerbating the ATP release. After reaching concentrations >300 μM extracellular ATP acts as a danger-associated molecular pattern, causing capillary leakage, alveolar space edema, and further deactivation of surfactant by serum proteins. Decreasing the tidal volume to 6 mL/kg or less at this stage cannot prevent further lung injury.

Regional overdistension during prone positioning in a patient with acute respiratory failure who was ventilated with a low tidal volume: a case report.

BACKGROUND: Prone positioning may provide a uniform distribution of transpulmonary pressure and contribute to prevent ventilator-induced lung injury. However, despite moderate positive end-expiratory pressure and low tidal volumes, there is still a risk of regional overdistension. CASE PRESENTATION: A man with refractory hypoxemia was mechanically ventilated with prone positioning. Although prone positioning with a plateau pressure of 18 cmH2O and a positive end-expiratory pressure of 8 cmH2O promptly improved oxygenation, regional ventilation monitoring using electrical impedance tomography initially detected decreased distribution in the dorsal region but increased in the ventral, suggesting overdistension. CONCLUSIONS: Our experience indicates monitoring regional ventilation distribution is useful for decreasing the risk of overdistension during prone positioning.

Electrical impedance tomography and trans-pulmonary pressure measurements in a patient with extreme respiratory drive.

Preserving spontaneous breathing during mechanical ventilation prevents muscle atrophy of the diaphragm, but may lead to ventilator induced lung injury (VILI). We present a case in which monitoring of trans-pulmonary pressure and ventilation distribution using Electrical Impedance Tomography (EIT) provided essential information for preventing VILI.

Roles of neurally adjusted ventilatory assist in improving gas exchange in a severe acute respiratory distress syndrome patient after weaning from extracorporeal membrane oxygenation: a case report.

BACKGROUND: Patient-ventilator asynchrony is a major cause of difficult weaning from mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) is reported useful to improve the synchrony in patients with sustained low lung compliance. However, the role of NAVA has not been fully investigated. CASE PRESENTATION: The patient was a 63-year-old Japanese man with acute respiratory distress syndrome secondary to respiratory infection. He was treated with extracorporeal membrane oxygenation for 7 days and survived. Dynamic compliance at withdrawal of extracorporeal membrane oxygenation decreased to 20 ml/cmH2O or less, but gas exchange was maintained by full support with assist/control mode. However, weaning from mechanical ventilation using a flow trigger failed repeatedly because of patient-ventilator asynchrony with hypercapnic acidosis during partial ventilator support despite using different types of ventilators and different trigger levels. Weaning using NAVA restored the regular respiration and stable and normal acid-base balance. Electromyographic analysis of the diaphragm clearly showed improved triggering of both the start and the end of spontaneous inspiration. Regional ventilation monitoring using electrical impedance tomography showed an increase in tidal volume and a ventilation shift to the dorsal regions during NAVA, indicating that NAVA could deliver gas flow to the dorsal regions to adjust for the magnitude of diaphragmatic excursion. NAVA was applied for 31 days, followed by partial ventilatory support with a conventional flow trigger. The patient was discharged from the intensive care unit on day 110 and has recovered enough to be able to live without a ventilatory support for 5 h per day. CONCLUSION: Our experience showed that NAVA improved not only patient-ventilator synchrony but also regional ventilation distribution in an acute respiratory distress patient with sustained low lung compliance.

Interrater Reliability and Diagnostic Performance of Subjective Evaluation of Sublingual Microcirculation Images by Physicians and Nurses: A Multicenter Observational Study.

INTRODUCTION: This was a cross-sectional multicenter study to investigate the ability of physicians and nurses from three different countries to subjectively evaluate sublingual microcirculation images and thereby discriminate normal from abnormal sublingual microcirculation based on flow and density abnormalities. METHODS: Forty-five physicians and 61 nurses (mean age, 36 ± 10 years; 44 males) from three different centers in The Netherlands (n = 61), Uruguay (n = 12), and Japan (n = 33) were asked to subjectively evaluate a sample of 15 microcirculation videos randomly selected from an experimental model of endotoxic shock in pigs. All videos were first analyzed offline using the A.V.A. software by an independent, experienced investigator and were categorized as good, bad, or very bad microcirculation based on the microvascular flow index, perfused capillary density, and proportion of perfused capillaries. Then, the videos were randomly assigned to the examiners, who were instructed to subjectively categorize each image as good, bad, or very bad. An interrater analysis was performed, and sensitivity and specificity tests were calculated to evaluate the proportion of A.V.A. score abnormalities that the examiners correctly identified. RESULTS: The κ statistics indicated moderate agreement in the evaluation of microcirculation abnormalities using three categories, i.e., good, bad, or very bad (κ = 0.48), and substantial agreement using two categories, i.e., normal (good) and abnormal (bad or very bad) (κ = 0.66). There was no significant difference between the κ three and κ two statistics. We found that the examiner's subjective evaluations had good diagnostic performance and were highly sensitive (84%; 95% confidence interval, 81%-86%) and specific (87%; 95% confidence interval, 84%-90%) for sublingual microcirculatory abnormalities as assessed using the A.V.A. software. CONCLUSIONS: The subjective evaluations of sublingual microcirculation by physicians and nurses agreed well with a conventional offline analysis and were highly sensitive and specific for sublingual microcirculatory abnormalities.

Fatal septicemia and endotoxic shock due to Aeromonas hydrophila.

BACKGROUND: Although rare, bloodstream infections caused by Aeromonas tend to be very severe and progress rapidly. CASE REPORT: We report a case of an 81-year-old man with fetal septicemia and endotoxin shock caused by Aeromonas hydrophila. The patient had dilated cardiomyopathy, paroxysmal atrial fibrillation, interstitial pneumonitis and renal dysfunction was admitted to our hospital with chest pain and dyspnea. Transthoracic echocardiography demonstrated impaired left ventricular wall motion and severe mitral regurgitation due to tethering. Cardiac catheterization revealed severe stenotic lesions in the left anterior descending artery and the right coronary artery. Surgery for coronary artery bypass grafts and mitral annuloplasty were performed. However, 2 days after surgery, he suddenly developed a high-grade fever and his hemodynamics deteriorated rapidly. His blood cultures revealed gram-negative Bacillus and the endotoxin concentration in the blood was elevated. Despite intensive support efforts, the patient died 1 day after the sudden change. His blood culture revealed A. hydrophila. CONCLUSIONS: Whenever Aeromonas is found in a patient's bloodstream, clinicians should start appropriate and intensive treatment immediately.

Preoperative epidural fentanyl reduces postoperative pain after upper abdominal surgery.

Forty patients, American Society of Anesthesiology (ASA) physical status 1-2, undergoing subtotal gastrectomy were enrolled in this study. The patients were allocated to two groups with or (group P) and without (group C) preoperative epidural fentanyl 100 microg. Postoperatively, all patients received continuous infusion of the study solution, containing fentanyl 30 microg x ml(-1) and 2 mg/ml bupivacaine, at a rate of 0.7 ml x h(-1) for 72 h. The scores on the Prince Henry Hospital self-assessed pain scale (PHPS) were recorded at 0, 4, 12, 24, 48, and 72 h after the surgery. We compared the total rescue doses of analgesics during each period of 24 h until 72 h postoperatively. Although the total rescue doses of analgesics were not different between the groups, the median PHPS score was lower in group P than in group C, except at 0 h after the surgery. Preoperative epidural fentanyl 100 microg may increase the analgesic potency of postoperative epidural low-dose infusion of bupivacaine with fentanyl.

[Anesthetic management of an obese patient with osteogenesis imperfecta].

Osteogenesis imperfecta (OI) is a rare hereditary disorder characterized by an excessive tendency to bone fractures and retarded growth, as well as variable involvement of other connective tissues such as teeth, sclerae, auditory bones and ligaments. A 30-year-old woman (body mass index of 39.6) with OI was scheduled for appendectomy. Because of obesity, abnormal cervical spine mobility and fragile teeth, in addition to the risk of mandibular and facial fractures, general anesthesia including airway management was considered to be difficult and, thus, avoided. Instead, neuraxial blocks were chosen. Although technical difficulty was expected with the blocks as well, epidural and spinal blocks were successfully performed using image intensifier. Neuraxial blocks for patients with skeletal abnormalities in the lumbar spine such as OI have been considered as relative contraindication. However, as described in this case report, these patients, in whom general anesthesia should be avoided, can benefit from neuraxial blocks with the help of image intensifier.