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Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study.

ABSTRACT: BACKGROUND:Percutaneous dilatational tracheotomy (PDT) may lead to transient impairment of pulmonary function due to suboptimal ventilation, loss of positive end-expiratory pressure (PEEP) and repetitive suction maneuvers during the procedure. Possible changes in regional lung aeration were investigated using electrical impedance tomography (EIT), an increasingly implied instrument for bedside monitoring of pulmonary aeration. METHODS:With local ethics committee approval, after obtaining written informed consent 29 patients scheduled for elective PDT under bronchoscopic control were studied during mechanical ventilation in supine position. Anesthetized patients were monitored with a 16-electrode EIT monitor for 2 min at four time points: (a) before and (b) after initiation of neuromuscular blockade (NMB), (c) after dilatational tracheostomy (PDT) and (d) after a standardized recruitment maneuver (RM) following surgery, respectively. Possible changes in lung aeration were detected by changes in end-expiratory lung impedance (? EELI). Global and regional ventilation was characterized by analysis of tidal impedance variation. RESULTS:While NMB had no detectable effect on EELI, PDT led to significantly reduced EELI in dorsal lung regions as compared to baseline, suggesting reduced regional aeration. This effect could be reversed by a standardized RM. Mean delta EELI from baseline (SE) was: NMB -?47?±?62; PDT -?490?±?180; RM -?89?±?176, values shown as arbitrary units (a.u.). Analysis of regional tidal impedance variation, a robust measure of regional ventilation, did not show significant changes in ventilation distribution. CONCLUSION:Though changes of EELI might suggest temporary loss of aeration in dorsal lung regions, PDT does not lead to significant changes in either regional ventilation distribution or oxygenation.

SUBMITTER: Eichler L

PROVIDER: S-EPMC6238017 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study.

Eichler Lars L Mueller Jakob J Grensemann Jörn J Frerichs Inez I Zöllner Christian C Kluge Stefan S

Annals of intensive care 20181115 1

<h4>Background</h4>Percutaneous dilatational tracheotomy (PDT) may lead to transient impairment of pulmonary function due to suboptimal ventilation, loss of positive end-expiratory pressure (PEEP) and repetitive suction maneuvers during the procedure. Possible changes in regional lung aeration were investigated using electrical impedance tomography (EIT), an increasingly implied instrument for bedside monitoring of pulmonary aeration.<h4>Methods</h4>With local ethics committee approval, after ob ...[more]

PMID: 30443867

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Project description:BackgroundNoninvasive monitoring of maximal inspiratory and expiratory flows (MIF and MEF, respectively) by electrical impedance tomography (EIT) might enable early recognition of changes in the mechanical properties of the respiratory system due to new conditions or in response to treatments. We aimed to validate EIT-based measures of MIF and MEF against spirometry in intubated hypoxemic patients during controlled ventilation and spontaneous breathing. Moreover, regional distribution of maximal airflows might interact with lung pathology and increase the risk of additional ventilation injury. Thus, we also aimed to describe the effects of mechanical ventilation settings on regional MIF and MEF.MethodsWe performed a new analysis of data from two prospective, randomized, crossover studies. We included intubated patients admitted to the intensive care unit with acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS) undergoing pressure support ventilation (PSV, n?=?10) and volume-controlled ventilation (VCV, n?=?20). We measured MIF and MEF by spirometry and EIT during six different combinations of ventilation settings: higher vs. lower support during PSV and higher vs. lower positive end-expiratory pressure (PEEP) during both PSV and VCV. Regional airflows were assessed by EIT in dependent and non-dependent lung regions, too.ResultsMIF and MEF measured by EIT were tightly correlated with those measured by spirometry during all conditions (range of R2 0.629-0.776 and R2 0.606-0.772, respectively, p?<?0.05 for all), with clinically acceptable limits of agreement. Higher PEEP significantly improved homogeneity in the regional distribution of MIF and MEF during volume-controlled ventilation, by increasing airflows in the dependent lung regions and lowering them in the non-dependent ones.ConclusionsEIT provides accurate noninvasive monitoring of MIF and MEF. The present study also generates the hypothesis that EIT could guide PSV and PEEP settings aimed to increase homogeneity of distending and deflating regional airflows.

Project description:BACKGROUND:Hypoxemia is the most common complication during tracheal intubation of critically ill adults and may increase the risk of cardiac arrest and death. Whether positive-pressure ventilation with a bag-mask device (bag-mask ventilation) during tracheal intubation of critically ill adults prevents hypoxemia without increasing the risk of aspiration remains controversial. METHODS:In a multicenter, randomized trial conducted in seven intensive care units in the United States, we randomly assigned adults undergoing tracheal intubation to receive either ventilation with a bag-mask device or no ventilation between induction and laryngoscopy. The primary outcome was the lowest oxygen saturation observed during the interval between induction and 2 minutes after tracheal intubation. The secondary outcome was the incidence of severe hypoxemia, defined as an oxygen saturation of less than 80%. RESULTS:Among the 401 patients enrolled, the median lowest oxygen saturation was 96% (interquartile range, 87 to 99) in the bag-mask ventilation group and 93% (interquartile range, 81 to 99) in the no-ventilation group (P?=?0.01). A total of 21 patients (10.9%) in the bag-mask ventilation group had severe hypoxemia, as compared with 45 patients (22.8%) in the no-ventilation group (relative risk, 0.48; 95% confidence interval [CI], 0.30 to 0.77). Operator-reported aspiration occurred during 2.5% of intubations in the bag-mask ventilation group and during 4.0% in the no-ventilation group (P?=?0.41). The incidence of new opacity on chest radiography in the 48 hours after tracheal intubation was 16.4% and 14.8%, respectively (P?=?0.73). CONCLUSIONS:Among critically ill adults undergoing tracheal intubation, patients receiving bag-mask ventilation had higher oxygen saturations and a lower incidence of severe hypoxemia than those receiving no ventilation. (Funded by Vanderbilt Institute for Clinical and Translational Research and others; PreVent ClinicalTrials.gov number, NCT03026322.).

Project description:BackgroundBesides airway suctioning, patients undergoing invasive mechanical ventilation (iMV) benefit of different combinations of chest physiotherapy techniques, to improve mucus removal. To date, little is known about the clearance effects of oscillating devices on patients with acute respiratory failure undergoing iMV. This study aimed to assess (1) the effects of high-frequency chest wall oscillation (HFCWO) on lung aeration and ventilation distribution, as assessed by electrical impedance tomography (EIT), and (2) the effect of the association of HFCWO with recruitment manoeuvres (RM).MethodsSixty critically ill patients, 30 classified as normosecretive and 30 as hypersecretive, who received ≥ 48 h of iMV, underwent HFCWO; patients from both subgroups were randomized to receive RM or not, according to two separated randomization sequences. We therefore obtained four arms of 15 patients each. After baseline record (T0), HFCWO was applied for 10 min. At the end of the treatment (T1) or after 1 (T2) and 3 h (T3), EIT data were recorded. At the beginning of each step, closed tracheobronchial suctioning was performed. In the RM subgroup, tracheobronchial suctioning was followed by application of 30 cmH2O to the patient's airway for 30 s. At each step, we assessed the change in end-expiratory lung impedance (ΔEELI) and in tidal impedance variation (ΔTIV), and the center of gravity (COG) through EIT. We also analysed arterial blood gases (ABGs).ResultsΔTIV and COG did not differ between normosecretive and hypersecretive patients. Compared to T0, ΔEELI significantly increased in hypersecretive patients at T2 and T3, irrespective of the RM; on the contrary, no differences were observed in normosecretive patients. No differences of ABGs were recorded.ConclusionsIn hypersecretive patients, HFCWO significantly improved aeration of the dorsal lung region, without affecting ABGs. The application of RM did not provide any further improvements.Trial registrationProspectively registered at the Australian New Zealand Clinical Trial Registry ( www.anzctr.org.au ; number of registration: ACTRN12615001257550; date of registration: 17th November 2015).

Project description:ObjectivesTo 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.DesignProspective interventional trial.SettingTwo PICUs.PatientsEight children with early acute respiratory distress syndrome (< 72 hr).InterventionsOn 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 resultsLung 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).ConclusionsElectrical 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.

Dataset Information

Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study.

Publications

Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study.

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