Regional expiratory time constants in severe respiratory failure estimated by electrical impedance tomography: a feasibility study

Autor: Stephan H. Bohm, Tina Schreiber, Andreas D. Waldmann, Christian Karagiannidis, Stephan Strassmann, Wolfram Windisch, Péter L. Róka
Rok vydání: 2018
Předmět:
Adult
Male
Pulmonary Atelectasis
ARDS
medicine.medical_specialty
Time Factors
Expiratory time constant
Exacerbation
medicine.medical_treatment
Critical Care and Intensive Care Medicine
Pulmonary Disease
Chronic Obstructive
03 medical and health sciences
0302 clinical medicine
Internal medicine
Flow limitation
Electric Impedance
Humans
Medicine
Tomography
Electrical impedance tomography
Aged
Mechanical ventilation
Respiratory Distress Syndrome
Simplified Acute Physiology Score
COPD
Expiratory Time
business.industry
lcsh:Medical emergencies. Critical care. Intensive care. First aid
030208 emergency & critical care medicine
lcsh:RC86-88.9
Middle Aged
medicine.disease
030228 respiratory system
Respiratory failure
SAPS II
Cardiology
Feasibility Studies
Severe COPD
Female
Respiratory Insufficiency
business
Zdroj: Critical Care, Vol 22, Iss 1, Pp 1-10 (2018)
ISSN: 1364-8535
DOI: 10.1186/s13054-018-2137-3
Popis: Background Electrical impedance tomography (EIT) has been used to guide mechanical ventilation in ICU patients with lung collapse. Its use in patients with obstructive pulmonary diseases has been rare since obstructions could not be monitored on a regional level at the bedside. The current study therefore determines breath-by-breath regional expiratory time constants in intubated patients with chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). Methods Expiratory time constants calculated from the global impedance EIT signal were compared to the pneumatic volume signals measured with an electronic pneumotachograph. EIT-derived expiratory time constants were additionally determined on a regional and pixelwise level. However, regional EIT signals on a single pixel level could in principle not be compared with similar pneumatic changes since these measurements cannot be obtained in patients. For this study, EIT measurements were conducted in 14 intubated patients (mean Simplified Acute Physiology Score II (SAPS II) 35 ± 10, mean time on invasive mechanical ventilation 36 ± 26 days) under four different positive end-expiratory pressure (PEEP) levels ranging from 10 to 17 cmH2O. Only patients with moderate-severe ARDS or COPD exacerbation were included into the study, preferentally within the first days following intubation. Results Spearman’s correlation coefficient for comparison between EIT-derived time constants and those from flow/volume curves was between 0.78 for tau (τ) calculated from the global impedance signal up to 0.83 for the mean of all pixelwise calculated regional impedance changes over the entire PEEP range. Furthermore, Bland-Altman analysis revealed a corresponding bias of 0.02 and 0.14 s within the limits of agreement ranging from − 0.50 to 0.65 s for the aforementioned calculation methods. In addition, exemplarily in patients with moderate-severe ARDS or COPD exacerbation, different PEEP levels were shown to have an influence on the distribution pattern of regional time constants. Conclusions EIT-based determination of breath-by-breath regional expiratory time constants is technically feasible, reliable and valid in invasively ventilated patients with severe respiratory failure and provides a promising tool to individually adjust mechanical ventilation in response to the patterns of regional airflow obstruction. Trial registration German Trial Register DRKS 00011650, registered 01/31/17.
Databáze: OpenAIRE
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