Changes in ventilation distribution during general anesthesia measured with EIT in mechanically ventilated small children.

BACKGROUND: Atelectasis during general anesthesia is a risk for perioperative complications. EIT measurements were performed in mechanically ventilated healthy children during elective surgery to demonstrate the changes in ventilation distribution during general anesthesia. The ventilation distribution was quantified by calculating the Global Inhomogeneity index (GI). METHODS: EIT measurements were performed in 23 children (9 weeks-10 years) without lung disease to detect changes in regional ventilation during elective surgery. Three previously defined time points were marked during the measurement: after intubation and start of pressure-controlled ventilation (PCV), change to pressure support ventilation (PSV), and after extubation (spontaneous breathing-SB). Ventilation distribution based on regions of interest (ROI) and changes in end-expiratory volume (∆EELV) were collected at these time points and compared. The Global Inhomogeneity index was calculated at the beginning of pressure-controlled ventilation (PCV). RESULTS: With increasing spontaneous breathing, dorsal recruitment of atelectasis occurred. The dorsal ventilation fraction increased over the time of general anesthesia with increasing spontaneous breathing, whereas the ventral fraction decreased relatively (Difference ± 5.5 percentage points respectively; 95% CI; 3.5-7.4; p < 0.001). With the onset of spontaneous breathing, there was a significant reduction in end-expiratory volume (Difference: 105 ml; 95% CI, 75-135; p < 0.001). The GI of the lung-healthy ventilated children is 47% (SD ± 4%). CONCLUSION: Controlled ventilation of healthy children resulted in increased ventilation of the ventral and collapse of the dorsal lung areas. Restart of spontaneous breathing after cessation of surgery resulted in an increase in ventilation in the dorsal with decrease in the ventral lung areas. By calculating the GI, representing the ratio of more to less ventilated lung areas, revealed the presumed homogeneous distribution of ventilation. TRIAL REGISTRATION: ClinicalTrials.gov Registration ID: NCT04873999. First registration: 05/05/2021.

High neutralizing antibody mismatch as a possible reason for vaccine failure in two children with severe tick-borne encephalitis.

We describe two adolescents (13 and 16 years old) with severe tick-borne encephalitis (TBE) and vaccination breakthrough (VBT). Both suffer from severe persistent neurologic sequelae. Both patients had high TBE-IgG-titers after vaccination at the beginning of the infection and a low or missing TBE-IgM response (Type 2 vaccine failure). Neutralization tests show low titers against the respective infecting TBE virus strain and higher titers against the vaccine strain at the beginning of the infection implying an individual weak or impaired immune response to the respective virus as possible cause of TBE vaccine failure. We do not know of any similar observation or explanation for the phenomenon and at the moment can only speculate of a severe course correlated to highly mismatched IgG. This constellation of high TBE IgGs, the lack of immune response and a severe course strongly resembles the severe TBE courses that occurred in the past after TBE immunoglobulin administration. To our knowledge differentiation between structural and functional antibodies by neutralization tests with a) the affecting TBE virus strain and b) the vaccine virus strain in TBE vaccine failures has never been described before. We conclude (1) to consider a TBE virus infection also in vaccinated children presenting with meningoencephalitis, (2) to perform a broad immunological work-up in severe TBE especially after VBT, (3) to further study if high mismatch IgG's are a possible reason for vaccine failure.

Impact of the First COVID Lockdown on Accident- and Injury-Related Pediatric Intensive Care Admissions in Germany-A Multicenter Study.

Children's and adolescents' lives drastically changed during COVID lockdowns worldwide. To compare accident- and injury-related admissions to pediatric intensive care units (PICU) during the first German COVID lockdown with previous years, we conducted a retrospective multicenter study among 37 PICUs (21.5% of German PICU capacities). A total of 1444 admissions after accidents or injuries during the first lockdown period and matched periods of 2017-2019 were reported and standardized morbidity ratios (SMR) were calculated. Total PICU admissions due to accidents/injuries declined from an average of 366 to 346 (SMR 0.95 (CI 0.85-1.05)). Admissions with trauma increased from 196 to 212 (1.07 (0.93-1.23). Traffic accidents and school/kindergarten accidents decreased (0.77 (0.57-1.02 and 0.26 (0.05-0.75)), whereas household and leisure accidents increased (1.33 (1.06-1.66) and 1.34 (1.06-1.67)). Less neurosurgeries and more visceral surgeries were performed (0.69 (0.38-1.16) and 2.09 (1.19-3.39)). Non-accidental non-suicidal injuries declined (0.73 (0.42-1.17)). Suicide attempts increased in adolescent boys (1.38 (0.51-3.02)), but decreased in adolescent girls (0.56 (0.32-0.79)). In summary, changed trauma mechanisms entailed different surgeries compared to previous years. We found no evidence for an increase in child abuse cases requiring intensive care. The increase in suicide attempts among boys demands investigation.

Clinical and Epidemiological Features of a Family Cluster of Symptomatic and Asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infection.

In a family experiencing coronavirus disease 2019, the parents and 2 children aged 2 and 5 years became infected but the youngest child was not infected. Both children initially shed infectious virus, but cleared the virus after 5 to 6 days in the nasopharynx. However, viral RNA was continuously detected in the children's stool for more than 4 weeks.

Mechanical Ventilation Guided by Electrical Impedance Tomography in Children With Acute Lung Injury.

OBJECTIVES: To provide proof-of-concept for a protocol applying a strategy of personalized mechanical ventilation in children with acute respiratory distress syndrome. Positive end-expiratory pressure and inspiratory pressure settings were optimized using real-time electrical impedance tomography aiming to maximize lung recruitment while minimizing lung overdistension. DESIGN: Prospective interventional trial. SETTING: Two PICUs. PATIENTS: Eight children with early acute respiratory distress syndrome (< 72 hr). INTERVENTIONS: On 3 consecutive days, electrical impedance tomography-guided positive end-expiratory pressure titration was performed by using regional compliance analysis. The Acute Respiratory Distress Network high/low positive end-expiratory pressure tables were used as patient's safety guardrails. Driving pressure was maintained constant. Algorithm includes the following: 1) recruitment of atelectasis: increasing positive end-expiratory pressure in steps of 4 mbar; 2) reduction of overdistension: decreasing positive end-expiratory pressure in steps of 2 mbar until electrical impedance tomography shows collapse; and 3) maintaining current positive end-expiratory pressure and check regional compliance every hour. In case of derecruitment start at step 1. MEASUREMENTS AND MAIN RESULTS: Lung areas classified by electrical impedance tomography as collapsed or overdistended were changed on average by -9.1% (95% CI, -13.7 to -4.4; p < 0.001) during titration. Collapse was changed by -9.9% (95% CI, -15.3 to -4.5; p < 0.001), while overdistension did not increase significantly (0.8%; 95% CI, -2.9 to 4.5; p = 0.650). A mean increase of the positive end-expiratory pressure level (1.4 mbar; 95% CI, 0.6-2.2; p = 0.008) occurred after titration. Global respiratory system compliance and gas exchange improved (global respiratory system compliance: 1.3 mL/mbar, 95% CI [-0.3 to 3.0], p = 0.026; Pao2: 17.6 mm Hg, 95% CI [7.8-27.5], p = 0.0039; and Pao2/Fio2 ratio: 55.2 mm Hg, 95% CI [27.3-83.2], p < 0.001, all values are change in pre vs post). CONCLUSIONS: Electrical impedance tomography-guided positive end-expiratory pressure titration reduced regional lung collapse without significant increase of overdistension, while improving global compliance and gas exchange in children with acute respiratory distress syndrome.

Chest electrical impedance tomography examination, data analysis, terminology, clinical use and recommendations: consensus statement of the TRanslational EIT developmeNt stuDy group.

Electrical impedance tomography (EIT) has undergone 30 years of development. Functional chest examinations with this technology are considered clinically relevant, especially for monitoring regional lung ventilation in mechanically ventilated patients and for regional pulmonary function testing in patients with chronic lung diseases. As EIT becomes an established medical technology, it requires consensus examination, nomenclature, data analysis and interpretation schemes. Such consensus is needed to compare, understand and reproduce study findings from and among different research groups, to enable large clinical trials and, ultimately, routine clinical use. Recommendations of how EIT findings can be applied to generate diagnoses and impact clinical decision-making and therapy planning are required. This consensus paper was prepared by an international working group, collaborating on the clinical promotion of EIT called TRanslational EIT developmeNt stuDy group. It addresses the stated needs by providing (1) a new classification of core processes involved in chest EIT examinations and data analysis, (2) focus on clinical applications with structured reviews and outlooks (separately for adult and neonatal/paediatric patients), (3) a structured framework to categorise and understand the relationships among analysis approaches and their clinical roles, (4) consensus, unified terminology with clinical user-friendly definitions and explanations, (5) a review of all major work in thoracic EIT and (6) recommendations for future development (193 pages of online supplements systematically linked with the chief sections of the main document). We expect this information to be useful for clinicians and researchers working with EIT, as well as for industry producers of this technology.

Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT): case report of reversible coma and status epilepticus in an adolescent patient and review of the literature.

UNLABELLED: Steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), also termed Hashimoto's encephalopathy (HE), is a rare immune-mediated disorder and is also affecting children and adolescents. It is characterized by altered mental status, seizures, and cognitive dysfunction. Therapeutic options include steroid treatment and prognosis range from complete recovery, a relapsing course to long-term cognitive sequelae. We describe a previously healthy 13-year-old girl presenting to the emergency room with coma and refractory status epilepticus. Generalized tonic-clonic seizures persisted after pre-hospital infusion of antiepileptic medication. She was found to have highly elevated levels of thyroid-stimulating hormone and anti-thyroid peroxidase antibodies not only in blood but also in cerebrospinal fluid while showing negative results for traumatic, infectious, metabolic, toxic, neoplastic, or other known specific autoimmune diseases. Cranial neuroimaging revealed no abnormality. A diagnosis of SREAT was established, and the patient improved rapidly on corticosteroids and levothyroxine therapy. However, 3 months after the discontinuation of steroid treatment, the girl relapsed. The current literature regarding SREAT is reviewed and summarized. CONCLUSION: In children with SREAT, early diagnosis and treatment with corticosteroids is crucial and can lead to rapid clinical improvement. Clinicians should be aware of this uncommon but treatable condition, especially in female adolescents with unexplained seizures or an encephalopathic state.

Mechanical ventilation guided by electrical impedance tomography in experimental acute lung injury.

OBJECTIVE: To utilize real-time electrical impedance tomography to guide lung protective ventilation in an animal model of acute respiratory distress syndrome. DESIGN: Prospective animal study. SETTING: Animal research center. SUBJECTS: Twelve Yorkshire swine (15 kg). INTERVENTIONS: Lung injury was induced with saline lavage and augmented using large tidal volumes. The control group (n = 6) was ventilated using ARDSnet guidelines, and the electrical impedance tomography-guided group (n = 6) was ventilated using guidance with real-time electrical impedance tomography lung imaging. Regional electrical impedance tomography-derived compliance was used to maximize the recruitment of dependent lung and minimize overdistension of nondependent lung areas. Tidal volume was 6 mL/kg in both groups. Computed tomography was performed in a subset of animals to define the anatomic correlates of electrical impedance tomography imaging (n = 5). Interleukin-8 was quantified in serum and bronchoalveolar lavage samples. Sections of dependent and nondependent regions of the lung were fixed in formalin for histopathologic analysis. MEASUREMENTS AND MAIN RESULTS: Positive end-expiratory pressure levels were higher in the electrical impedance tomography-guided group (14.3 cm H2O vs. 8.6 cm H2O; p < 0.0001), whereas plateau pressures did not differ. Global respiratory system compliance was improved in the electrical impedance tomography-guided group (6.9 mL/cm H2O vs. 4.7 mL/cm H2O; p = 0.013). Regional electrical impedance tomography-derived compliance of the most dependent lung region was increased in the electrical impedance tomography group (1.78 mL/cm H2O vs. 0.99 mL/cm H2O; p = 0.001). Pao2/FIO2 ratio was higher and oxygenation index was lower in the electrical impedance tomography-guided group (Pao2/FIO2: 388 mm Hg vs. 113 mm Hg, p < 0.0001; oxygentation index, 6.4 vs. 15.7; p = 0.02) (all averages over the 6-hr time course). The presence of hyaline membranes (HM) and airway fibrin (AF) was significantly reduced in the electrical impedance tomography-guided group (HMEIT 42% samples vs. HMCONTROL 67% samples, p < 0.01; AFEIT 75% samples vs. AFCONTROL 100% samples, p < 0.01). Interleukin-8 level (bronchoalveolar lavage) did not differ between the groups. The upper and lower 95% limits of agreement between electrical impedance tomography and computed tomography were ± 16%. CONCLUSIONS: Electrical impedance tomography-guided ventilation resulted in improved respiratory mechanics, improved gas exchange, and reduced histologic evidence of ventilator-induced lung injury in an animal model. This is the first prospective use of electrical impedance tomography-derived variables to improve outcomes in the setting of acute lung injury.

Interaction of dependent and non-dependent regions of the acutely injured lung during a stepwise recruitment manoeuvre.

The benefit of treating acute lung injury with recruitment manoeuvres is controversial. An impediment to settling this debate is the difficulty in visualizing how distinct lung regions respond to the manoeuvre. Here, regional lung mechanics were studied by electrical impedance tomography (EIT) during a stepwise recruitment manoeuvre in a porcine model with acute lung injury. The following interaction between dependent and non-dependent regions consistently occurred: atelectasis in the most dependent region was reversed only after the non-dependent region became overdistended. EIT estimates of overdistension and atelectasis were validated by histological examination of lung tissue, confirming that the dependent region was primarily atelectatic and the non-dependent region was primarily overdistended. The pulmonary pressure-volume equation, originally designed for modelling measurements at the airway opening, was adapted for EIT-based regional estimates of overdistension and atelectasis. The adaptation accurately modelled the regional EIT data from dependent and non-dependent regions (R(2) > 0.93, P < 0.0001) and predicted their interaction during recruitment. In conclusion, EIT imaging of regional lung mechanics reveals that overdistension in the non-dependent region precedes atelectasis reversal in the dependent region during a stepwise recruitment manoeuvre.

Comparison of 2 lung recruitment strategies in children with acute lung injury.

BACKGROUND: Lung recruitment maneuvers are frequently used in the treatment of children with lung injury. Here we describe a pilot study to compare the acute effects of 2 commonly used lung recruitment maneuvers on lung volume, gas exchange, and hemodynamic profiles in children with acute lung injury. METHODS: In a prospective, non-randomized, crossover pilot study, 10 intubated pediatric subjects with lung injury sequentially underwent: a period of observation; a sustained inflation (SI) maneuver of 40 cm H2O for 40 seconds and open-lung ventilation; a staircase recruitment strategy (SRS) (which utilized 5 cm H2O increments in airway pressure, from a starting plateau pressure of 30 cm H2O and PEEP of 15 cm H2O); a downwards PEEP titration; and a 1 hour period of observation with PEEP set 2 cm H2O above closing PEEP. RESULTS: Arterial blood gases, lung mechanics, hemodynamics, and functional residual capacity were recorded following each step of the study and following each increment of the SRS. Both SI and SRS were effective in raising PaO2 and functional residual capacity. During the SRS maneuver we noted significant increases in dead-space ventilation, a decrease in carbon dioxide elimination, an increase in PaCO2, and a decrease in compliance of the respiratory system. Lung recruitment was not sustained following the decremental PEEP titration. CONCLUSIONS: SRS is effective in opening the lung in children with early acute lung injury, and is hemodynamically well tolerated. However, attention must be paid to PaCO2 during the SRS. Even minutes following lung recruitment, lungs may derecruit when PEEP is lowered beyond the closing pressure.

Reversal of dependent lung collapse predicts response to lung recruitment in children with early acute lung injury.

OBJECTIVE: To describe the resolution of regional atelectasis and the development of regional lung overdistension during a lung-recruitment protocol in children with acute lung injury. DESIGN: Prospective interventional trial. SETTING: Pediatric intensive care unit. PATIENTS: Ten children with early (<72 hrs) acute lung injury. INTERVENTIONS: Sustained inflation maneuver (positive airway pressure of 40 cm H2O for 40 secs), followed by a stepwise recruitment maneuver (escalating plateau pressures by 5 cm H2O every 15 mins) until physiologic lung recruitment, defined by PaO2 + PaCO2 ≥400 mm Hg, was achieved. Regional lung volumes and mechanics were measured using electrical impedance tomography. MEASUREMENTS AND MAIN RESULTS: Patients that responded to the stepwise lung-recruitment maneuver had atelectasis in 54% of the dependent lung regions, while nonresponders had atelectasis in 10% of the dependent lung regions (p = .032). In the pressure step preceding physiologic lung recruitment, a significant reversal of atelectasis occurred in 17% of the dependent lung regions (p = .016). Stepwise recruitment overdistended 8% of the dependent lung regions in responders, but 58% of the same regions in nonresponders (p < .001). Lung compliance in dependent lung regions increased in responders, while compliance in nonresponders did not improve. In contrast to the stepwise recruitment maneuver, the sustained inflation did not produce significant changes in atelectasis or oxygenation: atelectasis was only reversed in 12% of the lung (p = .122), and there was only a modest improvement in oxygenation (27 ± 14 mm Hg, p = .088). CONCLUSIONS: Reversal of atelectasis in the most dependent lung region preceded improvements in gas exchange during a stepwise lung-recruitment strategy. Lung recruitment of dependent lung areas was accompanied by considerable overdistension of nondependent lung regions. Larger amounts of atelectasis in dependent lung areas were associated with a positive response to a stepwise lung-recruitment maneuver.

Impact of model shape mismatch on reconstruction quality in electrical impedance tomography.

Electrical impedance tomography (EIT) is a low-cost, noninvasive and radiation free medical imaging modality for monitoring ventilation distribution in the lung. Although such information could be invaluable in preventing ventilator-induced lung injury in mechanically ventilated patients, clinical application of EIT is hindered by difficulties in interpreting the resulting images. One source of this difficulty is the frequent use of simple shapes which do not correspond to the anatomy to reconstruct EIT images. The mismatch between the true body shape and the one used for reconstruction is known to introduce errors, which to date have not been properly characterized. In the present study we, therefore, seek to 1) characterize and quantify the errors resulting from a reconstruction shape mismatch for a number of popular EIT reconstruction algorithms and 2) develop recommendations on the tolerated amount of mismatch for each algorithm. Using real and simulated data, we analyze the performance of four EIT reconstruction algorithms under different degrees of shape mismatch. Results suggest that while slight shape mismatch is well tolerated by all algorithms, using a circular shape severely degrades their performance.

Whither lung EIT: where are we, where do we want to go and what do we need to get there?

Breathing moves volumes of electrically insulating air into and out of the lungs, producing conductivity changes which can be seen by electrical impedance tomography (EIT). It has thus been apparent, since the early days of EIT research, that imaging of ventilation could become a key clinical application of EIT. In this paper, we review the current state and future prospects for lung EIT, by a synthesis of the presentations of the authors at the 'special lung sessions' of the annual biomedical EIT conferences in 2009-2011. We argue that lung EIT research has arrived at an important transition. It is now clear that valid and reproducible physiological information is available from EIT lung images. We must now ask the question: How can these data be used to help improve patient outcomes? To answer this question, we develop a classification of possible clinical scenarios in which EIT could play an important role, and we identify clinical and experimental research programmes and engineering developments required to turn EIT into a clinically useful tool for lung monitoring.

A unified approach for EIT imaging of regional overdistension and atelectasis in acute lung injury.

Patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) are vulnerable to ventilator-induced lung injury. Although this syndrome affects the lung heterogeneously, mechanical ventilation is not guided by regional indicators of potential lung injury. We used electrical impedance tomography (EIT) to estimate the extent of regional lung overdistension and atelectasis during mechanical ventilation. Techniques for tidal breath detection, lung identification, and regional compliance estimation were combined with the Graz consensus on EIT lung imaging (GREIT) algorithm. Nine ALI/ARDS patients were monitored during stepwise increases and decreases in airway pressure. Our method detected individual breaths with 96.0% sensitivity and 97.6% specificity. The duration and volume of tidal breaths erred on average by 0.2 s and 5%, respectively. Respiratory system compliance from EIT and ventilator measurements had a correlation coefficient of 0.80. Stepwise increases in pressure could reverse atelectasis in 17% of the lung. At the highest pressures, 73% of the lung became overdistended. During stepwise decreases in pressure, previously-atelectatic regions remained open at sub-baseline pressures. We recommend that the proposed approach be used in collaborative research of EIT-guided ventilation strategies for ALI/ARDS.

Pediatric respiratory diseases: 2011 update for the Rogers' Textbook of Pediatric Intensive Care.

OBJECTIVES: To review articles relevant to the field of pediatric respiratory disease that were published after the 2008 Rogers' Textbook of Pediatric Intensive Care. DATA SOURCES: The authors searched the PubMed database (http://www.ncbi.nlm.nih.gov/sites/entrez) from the National Library of Medicine for citations from the pediatric and adult literature relevant to pediatric status asthmaticus, bronchiolitis, pneumonia, acute lung injury, acute respiratory distress syndrome, and neonatal respiratory failure. The authors also searched the reference lists of key primary publications and recent review articles, and queried the National Institutes of Health's ClinicalTrials.gov Web site (www.clinicaltrials.gov) to obtain information about ongoing clinical trials for acute lung injury. The authors had knowledge of new publications in the field of respiratory monitoring, which were considered for inclusion in the review. STUDY SELECTION AND DATA EXTRACTION: The authors reviewed the promising articles and the decision to include any article in the review was based on its potential to inform pediatric intensive care practice or future research. DATA SYNTHESIS: Articles in six categories were selected for inclusion: status asthmaticus, bronchiolitis, pneumonia, acute lung injury/acute respiratory distress syndrome, respiratory monitoring, and neonatal respiratory failure. CONCLUSIONS: There have been important new developments relevant to the pathogenesis and management of pediatric respiratory diseases. In particular, new insights into the causal pathways of respiratory syncytial virus-induced airways disease can potentially lead to novel therapies. Computed tomography imaging of the injured lung during mechanical ventilation has opened new avenues for future research directed at testing new treatments in acute lung injury subpopulations defined according to lung mechanics. Promising new monitoring techniques may play a supporting role in the conduct of these studies. Finally, evidence from the neonatal literature recently has shown how the course and future consequences of respiratory failure in this population may be modified through more widespread use of noninvasive support.

Electrocardiographic guidance for the placement of gastric feeding tubes: a pediatric case series.

BACKGROUND: The placement of nasal or oral gastric tubes is one of the most frequently performed procedures in critically ill children; tube malposition, particularly in the trachea, is an important complication. Neurally adjusted ventilatory assist (NAVA) ventilation (available only on the Servo-i ventilator, Maquet Critical Care, Solna, Sweden) requires a proprietary-design catheter (Maquet Critical Care, Solna, Sweden) with embedded electrodes that detect the electrical activity of the diaphragm (EA(di)). The EA(di) catheter has the potential benefit of confirming proper positioning of a gastric catheter, based on and the EA(di) waveforms. METHODS: In a case series study, our multidisciplinary team used EA(di) guidance for immediate, real-time confirmation of proper nasal or oral gastric tube placement in 20 mechanically ventilated pediatric patients who underwent 23 oral or nasal gastric tube placements. The catheters were placed with our standard practice, with the addition of a team member monitoring the EA(di) waveforms. As the tube passes down the esophagus and posterior to the heart, a characteristic EA(di) pattern is identified and the position of the atrial signal confirms correct placement of the gastric tube. If the EA(di) waveforms indicate incorrect placement, the tube is repositioned until the proper EA(di) waveform pattern is obtained. Then proper tube placement is reconfirmed via auscultation over the stomach while air is injected into the catheter, checking the pH of fluid suctioned from the catheter (gastric pH indicates correct positioning), and/or radiograph. RESULTS: The group's median age was 3 years (range 4 d to 16 y). All 20 patients had successful gastric catheter placement. The EA(di) catheter provided characteristic patterns for correctly placed tubes, tubes malpositioned above or below the gastroesophageal junction, and curled tubes. Proper catheter position was confirmed via radiograph and/or gastric pH in all 20 patients. CONCLUSIONS: EA(di) guidance helps confirm proper gastric catheter position, is equivalent to our standard practice for confirming gastric catheter placement, and may reduce the need for radiographs and improve patient safety by avoiding catheter malpositions.