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

BACKGROUND: Positive end-expiratory pressure (PEEP) can potentially modulate inspiratory effort (ΔPes), which is the major determinant of self-inflicted lung injury. RESEARCH QUESTION: Does high PEEP reduce ΔPes in patients with moderate-to-severe ARDS on assisted ventilation? STUDY DESIGN AND METHODS: Sixteen patients with Pao2/Fio2 ≤ 200 mm Hg and ΔPes ≥ 10 cm H2O underwent a randomized sequence of four ventilator settings: PEEP = 5 cm H2O or PEEP = 15 cm H2O + synchronous (pressure support ventilation [PSV]) or asynchronous (pressure-controlled intermittent mandatory ventilation [PC-IMV]) inspiratory assistance. ΔPes and 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. RESULTS: ΔPes was not systematically different at high vs low PEEP (pressure support ventilation: median, 20 cm H2O; interquartile range (IQR), 15-24 cm H2O vs median, 15 cm H2O; IQR, 13-23 cm H2O; P = .24; pressure-controlled intermittent mandatory ventilation: median, 20; IQR, 18-23 vs median, 19; IQR, 17-25; P = .67, respectively). Similarly, respiratory system and transpulmonary driving pressures, 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 driving pressure, and transpulmonary driving pressure according to whether this increased or decreased respiratory system compliance (r = -0.85, P < .001; r = -0.75, P < .001; r = -0.80, P < .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 = .006). High PEEP caused variable recruitment and systematic redistribution of tidal volume toward dorsal lung regions, thereby reducing dynamic strain in ventral areas (pressure support ventilation: median, 0.49; IQR, 0.37-0.83 vs median, 0.96; IQR, 0.62-1.56; P = .003; pressure-controlled intermittent mandatory ventilation: median, 0.65; IQR, 0.42-1.31 vs median, 1.14; IQR, 0.79-1.52; P = .002). All results were consistent during synchronous and asynchronous inspiratory assistance. INTERPRETATION: The impact of high PEEP on ΔPes and lung stress is interindividually variable according to different effects on the 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. TRIAL REGISTRATION: ClinicalTrials.gov; No.: NCT04241874; URL: www. CLINICALTRIALS: gov.

Prone Positioning and Molecular Biomarkers in COVID and Non-COVID ARDS: A Narrative Review.

Prone positioning (PP) represents a therapeutic intervention with the proven capacity of ameliorating gas exchanges and ventilatory mechanics indicated in acute respiratory distress syndrome (ARDS). When PP is selectively applied to moderate-severe cases of ARDS, it sensitively affects clinical outcomes, including mortality. After the COVID-19 outbreak, clinical application of PP peaked worldwide and was applied in 60% of treated cases, according to large reports. Research on this topic has revealed many physiological underpinnings of PP, focusing on regional ventilation redistribution and the reduction of parenchymal stress and strain. However, there is a lack of evidence on biomarkers behavior in different phases and phenotypes of ARDS. Patients response to PP are, to date, decided on PaO2/FiO2 ratio improvement, whereas scarce data exist on biomarker tracking during PP. The purpose of this review is to explore current evidence on the clinical relevance of biomarkers in the setting of moderate-severe ARDS of different etiologies (i.e., COVID and non-COVID-related ARDS). Moreover, this review focuses on how PP may modulate biomarkers and which biomarkers may have a role in outcome prediction in ARDS patients.

Intensive Care Unit-Acquired Weakness after Liver Transplantation: Analysis of Seven Cases and a Literature Review.

Intensive Care Unit (ICU)-Acquired Weakness (ICU-AW) is a generalized muscle weakness that is clinically detected in critical patients and has no plausible etiology other than critical illness. ICU-AW is uncommon in patients undergoing orthotopic liver transplantation (OLT). Our report sheds light on the highest number of ICU-AW cases observed in a single center on OLT patients with early allograft dysfunction. Out of 282 patients who underwent OLT from January 2015 to June 2023, 7 (2.5%) developed generalized muscle weakness in the ICU and underwent neurophysiological investigations. The neurologic examination showed preserved extraocular, flaccid quadriplegia with the absence of deep tendon reflexes in all patients. Neurophysiological studies, including electromyography and nerve conduction studies, showed abnormalities with fibrillation potentials and the rapid recruitment of small polyphasic motor units in the examined muscles, as well as a reduced amplitude of the compound muscle action potential and sensory nerve action potential, with an absence of demyelinating features. Pre-transplant clinical status was critical in all patients. During ICU stay, early allograft dysfunction, acute kidney injury, prolonged mechanical ventilation, sepsis, hyperglycemia, and high blood transfusions were observed in all patients. Two patients were retransplanted. Five patients were alive at 90 days; two patients died. In non-cooperative OLT patients, neurophysiological investigations are essential for the diagnosis of ICU-AW. In this setting, the high number of red blood cell transfusions is a potential risk factor for ICU-AW.

Comparative evaluation of three total full-face masks for delivering Non-Invasive Positive Pressure Ventilation (NPPV): a bench study.

Historically, the oro-nasal mask has been the preferred interface to deliver Non-Invasive Positive Pressure Ventilation (NPPV) in critically ill patients. To overcome the problems related to air leaks and discomfort, Total Full-face masks have been designed. No study has comparatively evaluated the performance of the total Full-face masks available.The aim of this bench study was to evaluate the influence of three largely diffuse models of total Full -face masks on patient-ventilator synchrony and performance during pressure support ventilation. NPPV was applied to a mannequin, connected to an active test lung through three largely diffuse Full-face masks: Dimar Full-face mask (DFFM), Performax Full-face mask (RFFM) and Pulmodyne Full-face mask (PFFM).The performance analysis showed that the ΔPtrigger was significantly lower with PFFM (p < 0.05) at 20 breaths/min (RRsim) at both pressure support (iPS) levels applied, while, at RRsim 30, DFFM had the longest ΔPtrigger compared to the other 2 total full face masks (p < 0.05). At all ventilator settings, the PTP200 was significantly shorter with DFFM than with the other two total full-face masks (p < 0.05). In terms of PTP500 ideal index (%), we did not observe significant differences between the interfaces tested.The PFFM demonstrated the best performance and synchrony at low respiratory rates, but when the respiratory rate increased, no difference between all tested total full-face masks was reported.

Influence of total face masks design and circuit on synchrony and performance during pressure support ventilation: A bench study.

BACKGROUND: Few studies investigated the influence of the circuit applied during non-invasive ventilation (NIV) with a total face mask. The aim of this bench study was to evaluate the effects of separated inflow and outflow ports in a total face mask on patient ventilator interaction and performance during NIV through a total face mask. METHODS: A mannequin was connected to an active lung simulator. NIV was applied both via a standard total face mask (STFM) with a Y-piece connector for inflow/outflow gases and a modified total face mask (MTFM) with 2 different connectors for inflow and outflow gases. RESULTS: The MTFM showed both a significantly better patient-ventilator interaction and a significantly higher performance. The MTFM showed a significantly lower Δtrigger compared to STFM (p<0.01) and shorter value of PTPtrigger during all ventilator setting tested (p < 0.01). Significant differences in PTP 200, PTP 300, and PTP 500 were observed between the MTFM and STFM (p < 0.01) in all conditions tested. Concerning PTP 500 ideal index, in all the conditions tested, the MTFM presented higher values compared to STFM, although those differences were not statistically significant. At both RRsim and ventilator settings tested, the MTFM showed a significantly shorter Delaytrinsp and Delaytrexp compared to STFM (p < 0.01). At both RRsim tested and both ventilator settings, the MTFM showed a significantly longer Timesync compared to STFM (p < 0.01). CONCLUSIONS: The MTFM showed a significantly better patient ventilator interaction and a better ventilator performance, suggesting that this kind of total face mask design should be preferred in clinical practice.

Children and neonates anesthesia in magnetic resonance environment in Italy: an active call survey.

BACKGROUND: Pediatric anesthesia care in the Magnetic Resonance Imaging is a challenge for clinicians. The recent debate about the role of anesthetic agent on neural development, encouraged an evaluation of their actual activity in this environment. In this active call survey, the authors sought to delineate the Italian situation regarding national centers, staff involved, monitoring tools available and sedation techniques. METHODS: A complete sample of all national centers performing almost a pediatric discharge in the 2014 was obtained from Health Ministry registers. All Institutions were contacted for a prospective phone investigation and a three-section survey was fill out with the Physician in charge. A descriptive and exploratory analyzes about the organization setting of the Centers were performed. RESULTS: Among 876 Institution screened, only 106 (37%) met minimal criteria for inclusion. Children are managed by anesthesiologists in the 95% of cases, while neonates in the 54%. A dedicated nurse is present in 74% of centers. While a pulse oximetry is present in 100% of centers, the rate of prevalence of other monitoring is lower. A specific MRI-compatible ventilator is available in the 95% of Centers, but many tools are not equally homogenously distributed. Pharmacological approach is preferred in pediatric age (98%), but its use for newborns is reduced to 43%. CONCLUSIONS: We found significant heterogeneity in the daily clinical practice of sedation in MRI. Our results could be a starting point to evaluate the further evolution of approach to children and neonates in magnetic resonance setting. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04775641.

Protective effect of SARS-CoV-2 preventive measures against ESKAPE and Escherichia coli infections.

BACKGROUND/OBJECTIVES: We investigated whether behavioral precautions adopted during Coronavirus disease (COVID-19) pandemic also influenced the spreading and multidrug resistance (MDR) of ESKAPEEc (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii [AB], Pseudomonas aeruginosa, Enterobacter spp and Escherichia Coli, [EC]) among Intensive Care Unit (ICU) patients. SUBJECTS/METHODS: We performed a single-center retrospective study in adult patients admitted to our COVID-19-free surgical ICU. Only patients staying in ICU for more than 48 hours were included. The ESKAPEEc infections recorded during the COVID-19 period (June 1, 2020 - February 28, 2021) and in the corresponding pre-pandemic period (June 1, 2019 - February 28, 2020) were compared. An interrupted time series analysis was performed to rule out possible confounders. RESULTS: Overall, 173 patients in the COVID-19 period and 132 in the pre-COVID-19 period were investigated. The ESKAPEEc infections were documented in 23 (13.3%) and 35 (26.5%) patients in the pandemic and the pre-pandemic periods, respectively (p = 0.005). Demographics, diagnosis, comorbidities, type of surgery, Simplified Acute Physiology Score II, length of mechanical ventilation, hospital and ICU length of stay, ICU death rate, and 28-day hospital mortality were similar in the two groups. In comparison with the pre-pandemic period, no AB was recorded during COVID-19 period, (p = 0.017), while extended-spectrum beta-lactamase-producing EC infections significantly decreased (p = 0.017). Overall, the ESKAPEEc isolates during pandemic less frequently exhibited multidrug-resistant (p = 0.014). CONCLUSIONS: These findings suggest that a robust adherence to hygiene measures together with human contact restrictions in a COVID-19 free ICU might also restrain the transmission of ESKAPEEc pathogens.

Pain Management Optimisation by an Ultrasound-Guided Analgesic Technique in Outpatients with Plantar Fasciitis during High-Energy Extracorporeal Shock Wave Therapy.

OBJECTIVE: Several studies have demonstrated the efficacy of high-energy extracorporeal shock wave therapy (HESWT) for the treatment of painful foot diseases. A crucial complication of HESWT is the appearance of pain with the subsequent interruption of the procedure. The aim of this study was the evaluation of ultrasound (US)-guided posterior tibial nerve block (PTNB) efficacy in outpatients who discontinued the first application of HESWT due to surge of moderate-severe pain. METHODS: Twenty-one patients, scheduled for HESWT due to plantar fasciitis, who interrupted the treatment for surge of pain (numeric rating scale [NRS] 5), were enrolled. After interruption of the first treatment, the patients received US-guided PTNB for every subsequent HESWT session. The same skilled anaesthesiologist performed an US-guided PTNB all the times. Once the nerve was identified, the needle was inserted and 5ml mepivacaine 1% were injected. Intensity of pain during each procedure by NRS and evaluation of patient's adherence to the treatment were detected. RESULTS: The HESWT was split into only three applications giving in average about 0.25 mJ mm-2, and all patients completed the treatment sessions. US-guided PTNB showed a significant reduction of NRS (P < 0.01) between the first HEWST without anaesthesia and the three subsequent treatments under peripheral block. CONCLUSION: US-guided PTNB resulted a valid support for the HEWST in outpatients with plantar fasciitis because it reduced the pain during the procedure, allowing to minimise the patient discomfort and to give the therapeutic doses just in three sessions.

(1,3)-ß-D-Glucan-based empirical antifungal interruption in suspected invasive candidiasis: a randomized trial.

BACKGROUND: (1,3)-ß-D-Glucan has been widely used in clinical practice for the diagnosis of invasive Candida infections. However, such serum biomarker showed potential to guide antimicrobial therapy in order to reduce the duration of empirical antifungal treatment in critically ill septic patients with suspected invasive candidiasis. METHODS: This was a single-centre, randomized, open-label clinical trial in which critically ill patients were enrolled during the admission to the intensive care unit (ICU). All septic patients who presented invasive Candida infection risk factors and for whom an empirical antifungal therapy was commenced were randomly assigned (1:1) in those stopping antifungal therapy if (1,3)-ß-D-glucan was negative ((1,3)-ß-D-glucan group) or those continuing the antifungal therapy based on clinical rules (control group). Serum 1,3-ß-D-glucan was measured at the enrolment and every 48/72 h over 14 days afterwards. The primary endpoint was the duration of antifungal treatment in the first 30 days after enrolment. RESULTS: We randomized 108 patients into the (1,3)-ß-D-glucan (n = 53) and control (n = 55) groups. Median [IQR] duration of antifungal treatment was 2 days [1-3] in the (1,3)-ß-D-glucan group vs. 10 days [6-13] in the control group (between-group absolute difference in means, 6.29 days [95% CI 3.94-8.65], p < 0.001). Thirty-day mortality was similar (28.3% [(1,3)-ß-D-glucan group] vs. 27.3% [control group], p = 0.92) as well as the overall rate of documented candidiasis (11.3% [(1,3)-ß-D-glucan group] vs. 12.7% [control group], p = 0.94), the length of mechanical ventilation (p = 0.97) and ICU stay (p = 0.23). CONCLUSIONS: In critically ill septic patients admitted to the ICU at risk of invasive candidiasis, a (1,3)-ß-D-glucan-guided strategy could reduce the duration of empirical antifungal therapy. However, the safety of this algorithm needs to be confirmed in future, multicentre clinical trial with a larger population. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03117439 , retrospectively registered on 18 April 2017.

Pressure Support Ventilation (PSV) versus Neurally Adjusted Ventilatory Assist (NAVA) in difficult to wean pediatric ARDS patients: a physiologic crossover study.

BACKGROUND: Neurally adjusted ventilatory assist (NAVA) is an innovative mode for assisted ventilation that improves patient-ventilator interaction in children. The aim of this study was to assess the effects of patient-ventilator interaction comparing NAVA with pressure support ventilation (PSV) in patients difficult to wean from mechanical ventilation after moderate pediatric acute respiratory distress syndrome (PARDS). METHODS: In this physiological crossover study, 12 patients admitted in the Pediatric Intensive Care Unit (PICU) with moderate PARDS failing up to 3 spontaneous breathing trials in less than 7 days, were enrolled. Patients underwent three study conditions lasting 1 h each: PSV1, NAVA and PSV2. RESULTS: The Asynchrony Index (AI) was significantly reduced during the NAVA trial compared to both the PSV1 and PSV2 trials (p = 0.001). During the NAVA trial, the inspiratory and expiratory trigger delays were significantly shorter compared to those obtained during PSV1 and PSV2 trials (Delaytrinspp < 0.001, Delaytrexpp = 0.013). These results explain the significantly longer Timesync observed during the NAVA trial (p < 0.001). In terms of gas exchanges, PaO2 value significantly improved in the NAVA trial with respect to the PSV trials (p < 0.02). The PaO2/FiO2 ratio showed a significant improvement during the NAVA trial compared to both the PSV1 and PSV2 trials (p = 0.004). CONCLUSIONS: In this specific PICU population, presenting difficulty in weaning after PARDS, NAVA was associated with a reduction of the AI and a significant improvement in oxygenation compared to PSV mode. TRIAL REGISTRATION: ClinicalTrial.gov Identifier: NCT04360590 "Retrospectively registered".

High-Flow Nasal Cannula Versus Standard Oxygen Therapy After Extubation in Liver Transplantation: A Matched Controlled Study.

BACKGROUND: High-flow nasal cannula (HFNC) is a key component of oxygen therapy and has largely been used in patients with acute respiratory failure. We conducted a matched controlled study with the aim to compare the preventive use of oxygen therapy delivered by HFNC versus via air-entrainment mask (standard O2) after extubation in adult subjects with liver transplantation for reducing postextubation hypoxemia. METHODS: Twenty-nine subjects with liver transplantation who received HFNC after extubation (HFNC group) were matched 1:1 with 29 controls (standard O2 group) chosen from an historical group of 90 subjects admitted to the ICU during the previous 36 months. The primary outcome of the study was the incidence of hypoxemia at 1 h and 24 h after extubation. Secondary outcomes were the rate of weaning failure, ICU length of stay, and 28-d mortality. RESULTS: The incidence of hypoxemia was not significantly different between the HFNC and standard O2 groups at 1 h and 24 h after extubation. In the HFNC group, there was a trend toward a lower rate of weaning failure compared with the standard O2 group. ICU length of stay and 28-d mortality were similar in both groups. CONCLUSIONS: Early application of HFNC in the subjects with liver transplantation did not reduce the incidence of hypoxemia after extubation compared with standard O2 and did not modify the incidence of weaning failure, ICU length of stay, and 28-d mortality in this high-risk population of subjects. (ClinicalTrials.gov registration NCT03441854.).

Effects of Thyroid Hormone Treatment on Diaphragmatic Efficiency in Mechanically Ventilated Subjects With Nonthyroidal Illness Syndrome.

BACKGROUND: Several respiratory abnormalities can be present in primary hypothyroidism and can be reversed with adequate hormone treatment. However, the role of thyroid hormone replacement therapy on the respiratory system in patients with nonthyroidal illness syndrome is still unclear. This physiologic study evaluated the effect of thyroid hormone treatment on respiratory muscle function in subjects with nonthyroidal illness syndrome and while on mechanical ventilation. The primary end point was neuromechanical efficiency, which provides an estimate of the efficiency of diaphragmatic contraction. Secondary end points were the transdiaphragmatic pressure-time product and the swing of the electrical activity of the diaphragm, which reflect the work of breathing and inspiratory effort, respectively. METHODS: Fifteen subjects on mechanical ventilation for ≥48 h and with a diagnosis of nonthyroidal illness syndrome who had a failed spontaneous breathing trial, received intravenous triiodothyronine. The hormone was administered as an intravenous bolus of 0.4 µg/kg triiodothyronine, followed by continuous perfusion at 0.6 µg/kg for 24 h. Neuromechanical efficiency was calculated as the ratio between the drop in airway pressure during an expiratory occlusion and the corresponding electrical activity of the diaphragm peak. Recordings were taken at baseline and after 3, 6, and 24 h. RESULTS: After study completion, free triiodothyronine serum concentrations increased in all the subjects (mean ± SD increase, 0.84 ± 0.34 pg/mL). Neuromechanical efficiency showed no significant changes throughout the study (mean ± SD baseline, 1.40 ± 0.87 cm H2O/µV; 3 h, 1.28 ± 0.64 cm H2O/µV; 6 h, 1.33 ± 0.87 cm H2O/µV; 24 h, 1.41 ± 0.96 cm H2O/µV). Similarly, no variations in transdiaphragmatic pressure-time product per min (mean ± SD baseline, 238.1 ± 124 cm H2O × s/min; 3 h, 242.5 ± 140.3 cm H2O × s /min; 6 h, 247.5 ± 161.7 cm H2O × s/min; 24 h, 281.2 ± 201.2 cm H2O × s/min) or swing of electrical activity of the diaphragm (mean ± baseline, 20.9 ± 13.1 µV; 3 h, 17.2 ± 8.3 µV; 6 h, 17.4 ± 11.3 µV; 24 h, 20.3 ± 13.7 µV) were observed during hormone administration. CONCLUSIONS: In the subjects on mechanical ventilation who were admitted to the ICU with nonthyroidal illness syndrome, thyroid hormone replacement treatment did not yield any benefit on respiratory muscle function when assessed by neuromechanical efficiency, which indicated that, in these subjects restoring normal levels of serum thyroid hormones is debatable. (ClinicalTrials.gov registration NCT03157466.).

Postoperative respiratory failure in liver transplantation: Risk factors and effect on prognosis.

BACKGROUND: Postoperative respiratory failure (PRF, namely mechanical ventilation >48 hours) significantly affects morbidity and mortality in liver transplantation (LTx). Previous studies analyzed only one or two categories of PRF risk factors (preoperative, intraoperative or postoperative ones). The aims of this study were to identify PRF predictors, to assess the length of stay (LoS) in ICU and the 90-day survival according to the PRF in LTx patients. METHODS: Two classification approaches were used: systematic classification (recipient-related preoperative factors; intraoperative factors; logistic factors; donor factors; postoperative ICU factors; postoperative surgical factors) and patient/organ classification (patient-related general factors; native-liver factors; new-liver factors; kidney factors; heart factors; brain factors; lung factors). Two hundred adult non-acute patients were included. Missing analysis was performed. The competitive role of each factor was assessed. RESULTS: PRF occurred in 36.0% of cases. Among 28 significant PRF predictors at univariate analysis, 6 were excluded because of collinearity, 22 were investigated by ROC curves and by logistic regression analysis. Recipient age (OR = 1.05; p = 0.010), female sex (OR = 2.75; p = 0.018), Model for End-Stage Liver Disease (MELD, OR = 1.09; p<0.001), restrictive lung pattern (OR = 2.49; p = 0.027), intraoperative veno-venous bypass (VVBP, OR = 3.03; p = 0.008), pre-extubation PaCO2 (OR = 1.11; p = 0.003) and Model for Early Allograft Function (MEAF, OR = 1.37; p<0.001) resulted independent PRF risk factors. As compared to patients without PRF, the PRF-group had longer LoS (10 days IQR 7-18 versus 5 days IQR 4-7, respectively; p<0.001) and lower day-90 survival (86.0% versus 97.6% respectively, p<0.001). CONCLUSION: In conclusion, MELD, restrictive lung pattern, surgical complexity as captured by VVBP, pre-extubation PaCO2 and MEAF are the main predictors of PRF in non-acute LTx patients.

Effects of two different ventilation strategies on respiratory mechanics during robotic-gynecological surgery.

It is unknown which is the best ventilatory approach in patients scheduled for gynecological robotic surgery in Deep Trendelenburg position in terms of respiratory mechanics. 40 patients were enrolled: 20 patients received a standard ventilation and 20 patients received a protective ventilation. Gas exchanges, respiratory mechanics and hemodynamic parameters were recorded. No significant differences were found between the two groups in terms of respiratory mechanics. In both groups, there was a significant reduction of static compliance between Baseline and Extubation Time (p < 0.01), and a significant increase of pulmonary pressure at the same times (p < 0.01). In both groups, a significant reduction of pH (p < 0.01) and a significant increase of PaCO2 (p < 0.01) were observed between Baseline and Extubation Time. At the Extubation time, PaCO2 was significantly higher during protective ventilation compared to standard ventilation. In this particular surgical setting, a protective ventilation strategy did not improve the respiratory mechanics compared to the standard ventilation strategy and was ineffective on post-operative gas exchanges.

Comparative bench study evaluation of different infant interfaces for non-invasive ventilation.

BACKGROUND: To compare, in terms of patient-ventilator interaction and performance, a new nasal mask (Respireo, AirLiquide, FR) with the Endotracheal tube (ET) and a commonly used nasal mask (FPM, Fisher and Paykel, NZ) for delivering Pressure Support Ventilation (PSV) in an infant model of Acute Respiratory Failure (ARF). METHODS: An active test lung (ASL 5000) connected to an infant mannequin through 3 different interfaces (Respireo, ET and FPM), was ventilated with a standard ICU ventilator set in PSV. The test lung was set to simulate a 5.5 kg infant with ARF, breathing at 50 and 60 breaths/min). Non-invasive ventilation (NIV) mode was not used and the leaks were nearly zero. RESULTS: The ET showed the shortest inspiratory trigger delay and pressurization time compared to FPM and Respireo (p < 0.01). At each respiratory rate tested, the FPM showed the shortest Expiratory trigger delay compared to ET and Respireo (p < 0.01). The Respireo presented a lower value of Inspiratory pressure-time product and trigger pressure drop than ET (p < 0.01), while no significant difference was found in terms of pressure-time product at 300 and 500 ms. During all tests, compared with the FPM, ET showed a significantly higher tidal volume (VT) delivered (p < 0.01), while Respireo showed a trend toward an increase of tidal volume delivered compared with FPM. CONCLUSIONS: The ET showed a better patient-ventilator interaction and performance compared to both the nasal masks. Despite the higher internal volume, Respireo showed a trend toward an increase of the delivered tidal volume; globally, its efficiency in terms of patient-ventilator interaction was comparable to the FPM, which is the infant NIV mask characterized by the smaller internal volume among the (few) models on the market.

Intensive care unit patients with lower respiratory tract nosocomial infections: the ENIRRIs project.

The clinical course of intensive care unit (ICU) patients may be complicated by a large spectrum of lower respiratory tract infections (LRTI), defined by specific epidemiological, clinical and microbiological aspects. A European network for ICU-related respiratory infections (ENIRRIs), supported by the European Respiratory Society, has been recently established, with the aim at studying all respiratory tract infective episodes except community-acquired ones. A multicentre, observational study is in progress, enrolling more than 1000 patients fulfilling the clinical, biochemical and radiological findings consistent with a LRTI. This article describes the methodology of this study. A specific interest is the clinical impact of non-ICU-acquired nosocomial pneumonia requiring ICU admission, non-ventilator-associated LRTIs occurring in the ICU, and ventilator-associated tracheobronchitis. The clinical meaning of microbiologically negative infectious episodes and specific details on antibiotic administration modalities, dosages and duration are also highlighted. Recently released guidelines address many unresolved questions which might be answered by such large-scale observational investigations. In light of the paucity of data regarding such topics, new interesting information is expected to be obtained from our network research activities, contributing to optimisation of care for critically ill patients in the ICU.

Remifentanil effects on respiratory drive and timing during pressure support ventilation and neurally adjusted ventilatory assist.

We assessed the effects of varying doses of remifentanil on respiratory drive and timing in patients receiving Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatory Assist (NAVA). Four incrementing remifentanil doses were randomly administered to thirteen intubated patients (0.03, 0.05, 0.08, and 0.1µg·Kg-1·min-1) during both PSV and NAVA. We measured the patient's (Ti/Ttotneu) and ventilator (Ti/Ttotmec) duty cycle, the Electrical Activity of the Diaphragm (EAdi), the inspiratory (Delaytrinsp) and expiratory (Delaytrexp) trigger delays and the Asynchrony Index (AI). Increasing doses of remifentanil did not modify EAdi, regardless the ventilatory mode. In comparison to baseline, remifentanil infusion >0.05µg/Kg-1/min-1 produced a significant reduction of Ti/Ttotneu and Ti/Ttotmec, by prolonging the expiratory time. Delaytrinsp and Delaytrexp were significantly shorter in NAVA, respect to PSV. AI was not influenced by the different doses of remifentanil, but it was significantly lower during NAVA, compared to PSV. In conclusion remifentanil did not affect the respiratory drive, but only respiratory timing, without differences between modes.

Effects of dexmedetomidine and propofol on patient-ventilator interaction in difficult-to-wean, mechanically ventilated patients: a prospective, open-label, randomised, multicentre study.

BACKGROUND: Dexmedetomidine can be used for sedation of mechanically ventilated patients and has minor respiratory effects. The aim of this study was to compare the incidence of patient-ventilator dyssynchronies during sedation with dexmedetomidine or propofol. METHODS: We conducted a multicentre, prospective, open-label, randomised clinical trial, comparing dexmedetomidine with standard propofol sedation at three intensive care units of university hospitals in Italy. Twenty difficult-to-wean patients for whom the first weaning trial had failed and who were on pressure support ventilation were randomised to receive sedation with either dexmedetomidine or propofol at a similar level of sedation (Richmond Agitation-Sedation Scale [RASS] score +1 to -2). The asynchrony index (AI) was calculated using tracings of airflow, airway pressure and electrical activity of the diaphragm sampled at 0, 0.5, 1, 2, 6, 12, 18 and 24 h. RESULTS: The mean AI was lower with dexmedetomidine than with propofol from 2 h onwards, although the two groups significantly differed only at 12 h (2.68 % vs 9.10 %, p < 0.05). No further difference was observed at 18 and 24 h. CONCLUSIONS: When sedation with propofol and dexmedetomidine was compared at similar RASS scores of patients in whom first weaning trial had failed, the AI was lower with dexmedetomidine than with propofol, and this difference was statistically significant at 12 h. These results suggest that sedation with dexmedetomidine may offer some advantages in terms of patient-ventilator synchrony.