Spontaneous Breathing Patients Research Articles

Mechanical ventilation in septic shock

The aim of this study was to review the most recent literature on mechanical ventilation strategies in patients with septic shock. Indirect clinical trial evidence has refined the use of neuromuscular blocking agents, positive end-expiratory pressure (PEEP) and recruitment manoeuvres in septic shock patients with acute respiratory distress syndrome. Weaning strategies and devices have also been recently evaluated. The role of lung protective ventilation in patients with healthy lungs, while recognized, still needs to be further refined. The possible detrimental effects of spontaneous breathing in patients who develop acute respiratory distress syndrome is increasingly recognized, but clinical trial evidence is still lacking to confirm this hypothesis. A new concept of lung and diaphragm protective is emerging in the critical care literature, but its application will need a complex intervention implementation approach to allow adequate scrutiny of this concept and uptake by clinicians. Many advances in the management of the mechanically ventilated patient with sepsis and septic shock have occurred in recent years, but clinical trial evidence is still necessary to translate new hypotheses to the bedside and find the right balance between benefits and risks of these new strategies.

Indirect calorimetry: best results with close monitoring of the carbon dioxide fraction in exhaled air

This study describes methods to improve resting energy expenditure (REE) estimated by the indirect calorimetry by evaluating predictors for the achievement of steady-state conditions (SSC). Cross-sectional study carried out with 20 women (30.2 ± 4.1 years; 27.8 ± 6.7 kg/m2). Indirect calorimetry was performed with the Quark RMR® calorimeter, during a 15-min period. VO2 consumption and VCO2 production were measured and data was collected every 5 s. Specific spreadsheet was used to compute the values of Steady REE and Software REE (deltaREE). Bias and concordance between values were assessed by the Bland-Altman plot and Lin’s correlation coefficient. There is an almost perfect concordance between Software REE and Steady REE (p = 0.001). Steady% was important for predicting deltaREE while variation of carbon dioxide exhaled (CVFECO2) was significant to predict Steady%. Also, CVFECO2 was strongly and significantly correlated with the CV of VO2 (r = 0.83, p = 0001) and with the CV of VCO2 (r = 0.9, p = 0001). FECO2 should be sustained without huge variations to ensure SSC when using a calorimeter based on the canopy dilution technique with spontaneous breathing patients of similar characteristics. Also, these results suggest that since SSC occurs at least one time in the test, the Software REE may be considered reliable.

Prediction of the Effectiveness of Spontaneous Breathing in Patients with Brain Damage of Various Etiologies.

The aim of the study was to develop an informative method for assessing chemoreflex sensitivity and to evaluate its prognostic capacity for restoring spontaneous breathing in patients with brain damage of various etiologies. The study included 16 healthy volunteers and 38 patients on prolonged mechanical ventilation (VE) after a traumatic brain injury, anoxic brain damage, and cerebrovascular events. The external respiration variables were assessed from the initial level to the development of the first episode of desaturation with spO2 in the range of 90–80% against the background of normobaric hypoxia as indicators reflecting the development of adaptive ventilatory response and characterizing the state of peripheral chemoreflex sensitivity (PCS). The peripheral chemoreflex sensitivity index (PCSI) was calculated using the equation: PCSI = [RR(e) : RR(i)] × [Vt(e) : Vt(i)] × [VE(e) : VE(i)] × Vt(e) × VE(e), where PCSI is the peripheral chemoreflex sensitivity index in L2/min; RR(i) and RR(e); Vt(i) and Vt(e); VE(i) and VE(e) are the respiratory rate, tidal volume, minute ventilation initially (i), before a functional stress test, and during a functional test of normobaric hypoxia with spO2 in the range of 90–80% (e). With the PCSI values ≥15.6 L2/min, successful weaning from ventilators and recovery of spontaneous breathing are predicted. The sensitivity and specificity of PCSI were 78.57 [95% CI: 49.2–95.26] and 83.3% [95% CI: 62.6–95.26], respectively. The sensitivity and specificity of the traditional indicator of the success rate of weaning from ventilators and recovery of spontaneous breathing, Rapid Shallow Breathing Index (RSBI), in this cohort of patients was 69.23 [95% CI: 38.6–90.9] and 28.0% [95% CI: 12.03–49.3], respectively. A predictor of the patient’s weaning from mechanical ventilation is the assessment of peripheral chemoreflex sensitivity, which can be measured by a simple non-invasive bedside test based on measuring the difference in external ventilation parameters before and during a functional normobaric hypoxic trial.

Awake prone positioning of hypoxaemic patients with COVID-19: protocol for a randomised controlled open-label superiority meta-trial

IntroductionProne positioning (PP) is an effective first-line intervention to treat patients with moderate to severe acute respiratory distress syndrome (ARDS) receiving invasive mechanical ventilation, as it improves gas exchanges and...

Methods for a Seamless Transition From Tracheostomy to Spontaneous Breathing in Patients With COVID-19.

The COVID-19 pandemic has profoundly affected health care delivery worldwide. A small yet significant number of patients with respiratory failure will require prolonged mechanical ventilation while recovering from the viral-induced injury. The majority of reports thus far have focused on the epidemiology, clinical factors, and acute care of these patients, with less attention given to the recovery phase and care of those patients requiring extended time on mechanical ventilation. In this paper, we review the procedures and methods to safely care for patients with COVID-19 who require tracheostomy, gastrostomy, weaning from mechanical ventilation, and final decannulation. The guiding principles consist of modifications in the methods of airway care to safely prevent iatrogenesis and to promote safety in patients severely affected by COVID-19, including mitigation of aerosol generation to minimize risk for health care workers.

General anesthesia with preserved spontaneous breathing through an intubation tube

The aim of the study was to study the possibility of preserving spontaneous breathing in patients during planned surgical interventions under general anesthesia with tracheal intubation. Material and Methods: 112 patients who underwent planned surgical interventions under general endotracheal anesthesia were randomly divided into two groups. Patients of the first group underwent compulsory mechanical ventilation in the volume control mode, patients of the second group underwent assisted ventilation of the lungs in spontaneous breathing mode with apparatus support. Conclusion: According to the results of the study, the possibility of safe use of the spontaneous breathing mode with hardware support during some surgical interventions in patients with initially healthy lungs has been shown.

A Case Report of Extracorporeal Membrane Oxygenation and Hemadsorber Therapy in Septic Patient with Multiorgan Injury

Summary Diagnostic microbiology and management of sepsis have advanced, even though the complication of multiorgan dysfunction remains a significant cause of morbidity and mortality. An estimated incidence of sepsis in 2017 is about 48 million a year, including 11 million sepsis- related deaths, which represents 19.7% of all global deaths.(1,2) Acute respiratory distress syndrome (ARDS) is a devastating complication of sepsis, conventionally, a substantial number of patients require mechanical ventilation (MV) to avert hypoxemia and hypercapnia. However, MV per se can cause lung injury, accelerating the disease progression. The use of extracorporeal membrane oxygenation (ECMO) in the management of ARDS has grown considerably in the past decade. More recently, an increasing popularity of spontaneous breathing and awake patients undergoing ECMO is seen, as well as the use of various types of hemadsorbers for reducing pathologically increased inflammatory response.(3) The purpose of this case report is to review airway and multiorgan support management during ECMO.

May the initial CT scan predict the occurrence of delayed hemothorax in blunt chest trauma patients?

To assess the impact of delayed hemothorax on outcomes in blunt chest trauma patients without life-threatening condition at admission and characterize the predictive value of predefined anatomical factors for delayed hemothorax. In a single-centre retrospective study, every spontaneous breathing patient admitted for a blunt chest trauma without significant pleural effusion at ICU admission was included. A multivariable regression model was used to determine the covariate-adjusted odd of secondary respiratory complications in patients with delayed hemothorax ≥ 500ml. The characteristics of rib fractures (number, location and displacement) were integrated into a logistic regression model to determine variables associated with delayed hemothorax in multivariate analysis. Over the study period, 109 patients were included and the rate of delayed hemothorax ≥ 500ml was 36%. Patients with delayed hemothorax had higher rates of pulmonary infections (OR 4.8 [1.6-16.4]) but no statistical association between delayed hemothorax and secondary respiratory failure (OR 2.0 [0.4-9.4]). A posterior location and a displaced rib fracture were independent predictors of delayed hemothorax (OR 3.4 [1.3-8.6] and OR 2.3 [1.1-5.1], respectively). At least one displaced rib fracture was more specific of delayed hemothorax than the commonly used threshold of three or more rib fractures (81.3 vs. 51.5%). Delayed hemothorax is a frequent complication associated with increased risk of pulmonary infection. The posterior location and the displacement of at least one rib fracture in the initial CT scan were independent risk factors for predicting the occurrence of delayed hemothorax.

Is the Prone Position Helpful During Spontaneous Breathing in Patients With COVID-19?

Is the Prone Position Helpful During Spontaneous Breathing in Patients With COVID-19?

Expert consensus on preventing nosocomial transmission during respiratory care for critically ill patients infected by 2019 novel coronavirus pneumonia

Definite evidence has shown that the novel coronavirus (COVID-19) could be transmitted from person to person, so far more than 1 700 bedside clinicians have been infected. A lot of respiratory treatments for critically ill patients are deemed as high-risk factors for nosocomial transmission, such as intubation, manual ventilation by resuscitator, noninvasive ventilation, high-flow nasal cannula, bronchoscopy examination, suction and patient transportation, etc, due to its high possibility to cause or worsen the spread of the virus. As such, we developed this consensus recommendations on all those high-risk treatments, based on the current evidence as well as the resource limitation in some areas, with the aim to reduce the nosocomial transmission and optimize the treatment for the COVID-19 pneumonia patients. Those recommendations include: (1)Standard prevention and protection, and patient isolation; (2)Patient wearing mask during HFNC treatment; (3)Using dual limb ventilator with filters placed at the ventilator outlets, or using heat-moisture exchanger (HME) instead of heated humidification in single limb ventilator with HME placed between exhalation port and mask; avoid using mask with exhalation port on the mask; (4)Placing filter between resuscitator and mask or artificial airway; (5)For spontaneous breathing patients, placing mask for patients during bronchoscopy examination; for patients receiving noninvasive ventilation, using the special mask with bronchoscopy port to perform bronchoscopy; (6)Using sedation and paralytics during intubation, cuff pressure should be maintained between 25-30 cmH(2)O(1 cmH(2)O=0.098 kPa); (7)In-line suction catheter is recommended and it can be used for one week; (8)Dual-limb heated wire circuits are recommended and only changed with visible soiled; (9)For patients who need breathing support during transportation, placing an HME between ventilator and patient; (10)PSV is recommended for implementing spontaneous breathing trial (SBT), avoid using T-piece to do SBT. When tracheotomy patients are weaned from ventilator, HME should be used, avoid using T-piece or tracheostomy mask. (11)Avoid unnecessary bronchial hygiene therapy; (12) For patients who need aerosol therapy, dry powder inhaler metered dose inhaler with spacer is recommended for spontaneous breathing patients; while vibrating mesh nebulizer is recommended for ventilated patients and additional filter is recommended to be placed at the expiratory port of ventilation during nebulization.

Expert consensus on preventing nosocomial transmission during respiratory care for critically ill patients infected by 2019 novel coronavirus pneumonia

Definite evidence has shown that the novel coronavirus (COVID-19) could be transmitted from person to person, so far more than 1,700 bedside clinicians have been infected. A lot of respiratory treatments for critically ill patients are deemed as high-risk factors for nosocomial transmission, such as intubation, manual ventilation by resuscitator, noninvasive ventilation, high-flow nasal cannula, bronchoscopy examination, suction and patient transportation, etc, due to its high possibility to cause or worsen the spread of the virus. As such, we developed this consensus recommendations on all those high-risk treatments, based on the current evidence as well as the resource limitation in some areas, with the aim to reduce the nosocomial transmission and optimize the treatment for the COVID-19 pneumonia patients. Those recommendations include: (1) Standard prevention and protection, and patient isolation; (2) Patient wearing mask during HFNC treatment; (3) Using dual limb ventilator with filters placed at the ventilator outlets, or using heat-moisture exchanger (HME) instead of heated humidification in single limb ventilator with HME placed between exhalation port and mask; avoid using mask with exhalation port on the mask; (4) Placing filter between resuscitator and mask or artificial airway; (5) For spontaneous breathing patients, placing mask for patients during bronchoscopy examination; for patients receiving noninvasive ventilation, using the special mask with bronchoscopy port to perform bronchoscopy; (6) Using sedation and paralytics during intubation, cuff pressure should be maintained between 25-30 cmH(2)O; (7) In-line suction catheter is recommended and it can be used for one week; (8) Dual-limb heated wire circuits are recommended and only changed with visible soiled; (9. For patients who need breathing support during transportation, placing an HME between ventilator and patient; (10) PSV is recommended for implementing spontaneous breathing trial (SBT), avoid using T-piece to do SBT. When tracheotomy patients are weaned from ventilator, HME should be used, avoid using T-piece or tracheostomy mask. (11) Avoid unnecessary bronchial hygiene therapy; (12) For patients who need aerosol therapy, dry powder inhaler metered dose inhaler with spacer is recommended for spontaneous breathing patients; while vibrating mesh nebulizer is recommended for ventilated patients and additional filter is recommended to be placed at the expiratory port of ventilation during nebulization.

Impact of deep breathing on predictability of stroke volume variation in spontaneous breathing patients.

This study investigated the ability of stroke volume variation (SVV) during deep breathing to discriminate fluid responders among spontaneously breathing patients. Thirty patients undergoing general anaesthesia were enrolled and assessed before anaesthetic induction. Haemodynamic variables, including stroke volume (SV) and SVV, were measured using the ClearSight system during normal breathing. After these measurements, each patient was required to maintain deep breathing (6 breaths min-1 ) and haemodynamic variables were recorded. Then, the table was adjusted to the Trendelenburg position (15°) for 2minutes, and haemodynamic variables were measured. Receiver operating characteristic curves were created for SVV during normal and deep breathing, and the difference in SVV between normal and deep breathing (ΔSVV) to discriminate fluid responders (SV increase>10% after changing position). The correlation between SV increase and ΔSVV was examined using Pearson's correlation coefficient. The grey zone approach was used to assess the inconclusive range of the haemodynamic variables. Receiver operating characteristic curve analysis indicated that ΔSVV showed good reliability in predicting fluid responsiveness (AUC: 0.850; 95% CI: 0.672-0.953; threshold: 4%, sensitivity: 75.0%, specificity: 88.9%], while SVV during normal breathing did not (AUC: 0.579; 95% CI: 0.386-0.756)]. Although SVV during deep breathing exhibited acceptable predictability (AUC: 0.778; 95% CI: 0.589-0.908), the sensitivity was not good (58.3%). With the grey zone approach, the inconclusive range of ΔSVV was small with the range of 1.4%-4.2% (23% of patients). Deep breathing could improve the reliability of dynamic indices in spontaneously breathing patients. UMIN-CTR, identifer: UMIN000027970. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000032040.

Prediction of the effectiveness of spontaneous breathing in patients with brain damage of various etiologies

BACKGROUND: Long-term respiratory support is a severe disabling factor and is accompanied by a long stay of patients in intensive care units.
 AIMS: The analysis of the predictors of the success of disconnection from mechanical ventilation on the basis of clinical and diagnostic criteria in patients with brain damage of various etiologies.
 METHODS: The study included 53 patients (husband ― 28, women ― 25; cf. age 53.69 2.34) who are in 2019 with the consequences of traumatic brain injury (TBI) (n = 18; 33.9%); consequences of acute cerebrovascular accident (n = 24; 45.3%); the effects of anoxic brain damage (n = 3; 5.7%); consequences of subarachnoid hemorrhage (n = 8; 15.1%).
 RESULTS: The statistically significant predictor of recovery of spontaneous breathing in the 1st and 2nd groups of patients were preserved chemoreflex sensitivity (IPCS), the sensitivity and specificity of IPCS was 78.57% [95 % DI 49.295.26] and 83.3 % [95 % CI 62.695.26]. The index of peripheral chemoreflex sensitivity (IPCS) was calculated using the formula: IPCS = [RRe / RRi] [Vt(e) / Vt(i)] [VE(e) / VE(i)] [Vt(e) VE(i)], where IPCS is the index of peripheral chemoreflex sensitivity in l/min; RRi and RRe; Vt(i) and Vt(e); VE(e) and VE(i) ― respiratory rate (RR, breaths/min), tidal volume (Vt), minute ventilation (VE), (l/min) of the starting point ― (i) before carrying out a functional stress test and (e) ― during a functional test of normobaric hypoxia with SpO2 in the range of 9080 %.
 CONCLUSIONS: The most significant clinical parameters statistically reliably hampering the process of successful recovery of spontaneous breathing in addition to chemoreflex sensitivity are the presence of severe heart failure, pneumonia, autonomic dysfunction, level of consciousness, age, higher levels of inspiratory and expiratory pressure mounted on a respirator.

Spontaneous breathing in patients with severe acute respiratory distress syndrome receiving prolonged extracorporeal membrane oxygenation

BackgroundThe use of extracorporeal membrane oxygenation (ECMO) in awake, spontaneously breathing and non-intubated patients (awake ECMO) may be a novel therapeutic strategy for severe acute respiratory distress syndrome (ARDS) patients. The purpose of this study is to assess the feasibility and safety of awake ECMO in severe ARDS patients receiving prolonged ECMO (> 14 days).MethodsWe describe our experience with 12 consecutive severe ARDS patients (age, 39.1 ± 16.4 years) supported with awake ECMO to wait for native lung recovery during prolonged ECMO treatment from July 2013 to January 2018. Outcomes are reported including the hospital mortality, ECMO-related complications and physiological data on weaning from invasive ventilation.ResultsThe patients received median 26.0 (15.5, 64.8) days of total ECMO duration in the cohort. The longest ECMO support duration was 121 days. Awake ECMO and extubation was implemented after median 10.2(5.0, 42.9) days of ECMO. Awake ECMO was not associated with increased morbidity. The total invasive ventilation duration, lengths of stay in the ICU and hospital in the cohort were 14.0(12.0, 37.3) days, 33.0(22.3, 56.5) days and 46.5(27.3, 84.8) days, respectively. The hospital mortality rate was 33.3% (4/12) in the cohort. Survivors had more stable respiratory rate and heart rate after extubation when compared to the non-survivors.ConclusionsWith carefully selected patients, awake ECMO is a feasible and safe strategy for severe pulmonary ARDS patients receiving prolonged ECMO support to wait for native lung recovery.

Quantitative Assessment of Spontaneous Breathing in Children: Evaluation of a Depth Camera System

This article describes a new approach for quantitative evaluation of respiration in the pediatric intensive care unit (PICU). Video sequences of thorax movements are recorded by two depth cameras to cover the 3-D surface of the torso and its lateral sides. The breathing activity implies a frame-by-frame surface deformation, which can be described by the volume variation of reconstructed surfaces between the consecutive video frames. A quantitative evaluation of the breathing pattern is then performed through a subtraction technique, thereby detecting the volume variation between the subsequent frames. A high-fidelity simulation was performed in a realistic environment designed for critically ill children. The simulation was then followed by a real-world evaluation, involving two newborn babies (one female and one male) who required ventilator support. The breathing signal patterns resulting from our approach were compared to those measured by mechanical ventilation in terms of their waveforms, evaluating the most significant dynamic parameters: tidal volume, respiratory rate, and minute ventilation. Our experimental study showed a significant agreement between the proposed 3-D imaging system and the gold standard method in estimating respiratory waveforms and parameters. This article presents the following innovations. First, we suggest a 3-D imaging system specifically designed for PICUs based on a contactless design. Second, we propose an efficient positioning mechanism for the cameras, offering a very high spatial coverage of the thoracoabdominal zone and considering the PICU constraints. Finally, we propose an objective vision-based method to quantitatively measure respiration for spontaneous breathing patients in PICUs.

Patient asynchrony modelling during controlled mechanical ventilation therapy

Background and objectiveMechanical ventilation therapy of respiratory failure patients can be guided by monitoring patient-specific respiratory mechanics. However, the patient's spontaneous breathing effort during controlled ventilation changes airway pressure waveform and thus affects the model-based identification of patient-specific respiratory mechanics parameters. This study develops a model to estimate respiratory mechanics in the presence of patient effort. MethodsGaussian effort model (GEM) is a derivative of the single-compartment model with basis function. GEM model uses a linear combination of basis functions to model the nonlinear pressure waveform of spontaneous breathing patients. The GEM model estimates respiratory mechanics such as Elastance and Resistance along with the magnitudes of basis functions, which accounts for patient inspiratory effort. Results and discussionThe GEM model was tested using both simulated data and a retrospective observational clinical trial patient data. GEM model fitting to the original airway pressure waveform is better than any existing models when reverse triggering asynchrony is present. The fitting error of GEM model was less than 10% for both simulated data and clinical trial patient data. ConclusionGEM can capture the respiratory mechanics in the presence of patient effect in volume control ventilation mode and also can be used to assess patient-ventilator interaction. This model determines basis functions magnitudes, which can be used to simulate any waveform of patient effort pressure for future studies. The estimation of parameter identification GEM model can further be improved by constraining the parameters within a physiologically plausible range during least-square nonlinear regression.

Dexmedetomidine Sedation After Tracheal Surgery: A Prospective Pilot Study

Fourteen adults undergoing tracheal resection and reconstruction surgery were enrolled in this prospective observational pilot study to evaluate dexmedetomidine-based sedation after tracheal surgery in an intensive care unit. Patients remained electively intubated with an uncuffed nasal endotracheal tube, awake and exhibiting spontaneous breathing. The neck was maintained in flexion through chin-to-chest sutures. Infusion of dexmedetomidine was started from a dosage of 0.7 μg·kg-1·h-1 followed by dose titration to the target level of the sedation Richmond Agitation Sedation Scale (RASS) score -1 to -2 using a dose range of 0.2 to 1.4 μg·kg-1·h-1. The mean sedation levels were within the target ranges during the entire 18-hour observation period with a significant decrease in RASS (baseline RASS, 1.43 ± 0.51; 18h RASS -0.86 ± 0.95; p < 0.005). The mean arterial pressure (MAP) and heart rate (HR) weresignificantly decreased during dexmedetomidine infusion (baseline MAP 90.29 ± 14.33 mm Hg versus 18-hour MAP 82.50 ± 15.44 mm Hg; baseline HR 81.50 ± 12.76 beats/min versus 18-hour HR 69.29 ± 10.21 beats/min; p < 0.005). The visual analog scale (VAS) scores significantly decreased (baseline VAS 4.14 ± 0.86 versus 18-hour VAS 2.79 ± 0.67; p < 0.005). Peripheral oxygen saturation did not exhibit any significant decrease. Bradycardia occurred in 1 patient who assumed beta-blocker therapy without significant changes in blood pressure and was resolved by titration of the infusion without suspending sedation. No cases of delirium were encountered, and no additional sedative or analgesic was required. Dexmedetomidine provided safe and effective sedation after tracheal surgery in spontaneous breathing patients without causing respiratory depression.

High‐flow nasal therapy – modelling the mechanism

High‐flow nasal therapy – modelling the mechanism

Spontaneous Breathing in Early Acute Respiratory Distress Syndrome: Insights From the Large Observational Study to UNderstand the Global Impact of Severe Acute Respiratory FailurE Study.

To describe the characteristics and outcomes of patients with acute respiratory distress syndrome with or without spontaneous breathing and to investigate whether the effects of spontaneous breathing on outcome depend on acute respiratory distress syndrome severity. Planned secondary analysis of a prospective, observational, multicentre cohort study. International sample of 459 ICUs from 50 countries. Patients with acute respiratory distress syndrome and at least 2 days of invasive mechanical ventilation and available data for the mode of mechanical ventilation and respiratory rate for the 2 first days. Analysis of patients with and without spontaneous breathing, defined by the mode of mechanical ventilation and by actual respiratory rate compared with set respiratory rate during the first 48 hours of mechanical ventilation. Spontaneous breathing was present in 67% of patients with mild acute respiratory distress syndrome, 58% of patients with moderate acute respiratory distress syndrome, and 46% of patients with severe acute respiratory distress syndrome. Patients with spontaneous breathing were older and had lower acute respiratory distress syndrome severity, Sequential Organ Failure Assessment scores, ICU and hospital mortality, and were less likely to be diagnosed with acute respiratory distress syndrome by clinicians. In adjusted analysis, spontaneous breathing during the first 2 days was not associated with an effect on ICU or hospital mortality (33% vs 37%; odds ratio, 1.18 [0.92-1.51]; p = 0.19 and 37% vs 41%; odds ratio, 1.18 [0.93-1.50]; p = 0.196, respectively ). Spontaneous breathing was associated with increased ventilator-free days (13 [0-22] vs 8 [0-20]; p = 0.014) and shorter duration of ICU stay (11 [6-20] vs 12 [7-22]; p = 0.04). Spontaneous breathing is common in patients with acute respiratory distress syndrome during the first 48 hours of mechanical ventilation. Spontaneous breathing is not associated with worse outcomes and may hasten liberation from the ventilator and from ICU. Although these results support the use of spontaneous breathing in patients with acute respiratory distress syndrome independent of acute respiratory distress syndrome severity, the use of controlled ventilation indicates a bias toward use in patients with higher disease severity. In addition, because the lack of reliable data on inspiratory effort in our study, prospective studies incorporating the magnitude of inspiratory effort and adjusting for all potential severity confounders are required.

Chartis Measurement of Collateral Ventilation: Conscious Sedation versus General Anesthesia – A Retrospective Comparison

Background: Absence of interlobar collateral ventilation using the Chartis measurement is the key predictor for successful endobronchial valve treatment in severe emphysema. Chartis was originally validated in spontaneous breathing patients under conscious sedation (CS); however, this can be challenging due to cough, mucus secretion, mucosal swelling, and bronchoconstriction. Performing Chartis under general anesthesia (GA) avoids these problems and may result in an easier procedure with a higher success rate. However, using Chartis under GA with positive pressure ventilation has not been validated. Objectives: In this study we investigated the impact of anesthesia technique, CS versus GA, on the feasibility and outcomes of Chartis measurement. Methods: We retrospectively analyzed all Chartis measurements performed at our hospital from October 2010 until December 2017. Results: We analyzed 250 emphysema patients (median forced expiratory volume in 1 s 26%, range 12–52% predicted). In 121 patients (48%) the measurement was performed using CS, in 124 (50%) using GA, and in 5 (2%) both anesthesia techniques were used. In total, 746 Chartis readings were analyzed (432 CS, 277 GA, and 37 combination). Testing under CS took significantly longer than GA (median 19 min [range 5—65] vs. 11 min [3–35], p < 0.001) and required more measurements (3 [1–13] vs. 2 [1–6], p < 0.001). There was no significant difference in target lobe volume reduction after treatment (–1,123 mL [–3,604 to 332] in CS vs. –1,251 mL [–3,333 to –1] in GA, p = 0.35). Conclusions: In conclusion, Chartis measurement under CS took significantly longer and required more measurements than under GA, without a difference in treatment outcome. We recommend a prospective trial comparing both techniques within the same patients to validate this approach.