Abstract
BackgroundThe study objective was to compare titration of positive end-expiratory pressure (PEEP) with electrical impedance tomography (EIT) and with ventilator-embedded pressure–volume loop in severe acute respiratory distress syndrome (ARDS).MethodsWe have designed a prospective study with historical control group. Twenty-four severe ARDS patients (arterial oxygen partial pressure to fractional inspired oxygen ratio, PaO2/FiO2 < 100 mmHg) were included in the EIT group and examined prospectively. Data from another 31 severe ARDS patients were evaluated retrospectively (control group). All patients were receiving medical care under identical general support guidelines and protective mechanical ventilation. The PEEP level selected in the EIT group was the intercept point of cumulated collapse and overdistension percentages curves. In the control group, optimal PEEP was selected 2 cmH2O above the lower inflection point on the static pressure–volume curve.ResultsPatients in the EIT group were younger (P < 0.05), and their mean plateau pressure was 1.5 cmH2O higher (P < 0.01). No differences in other baseline parameters such as APACHE II score, PaO2/FiO2, initial PEEP, driving pressure, tidal volume, and respiratory system compliance were found. Two hours after the first PEEP titration, significantly higher PEEP, compliance, and lower driving pressure were found in the EIT group (P < 0.01). Hospital survival rates were 66.7% (16 of 24 patients) in the EIT group and 48.4% (15 of 31) in the control group. Identical rates were found regarding the weaning success rate: 66.7% in the EIT group and 48.4% in the control group.ConclusionIn severe ARDS patients, it was feasible and safe to guide PEEP titration with EIT at the bedside. As compared with pressure–volume curve, the EIT-guided PEEP titration may be associated with improved oxygenation, compliance, driving pressure, and weaning success rate. The findings encourage further randomized control study with a larger sample size and potentially less bias in the baseline data.Trial Registration NCT03112512
Highlights
The study objective was to compare titration of positive end-expiratory pressure (PEEP) with electri‐ cal impedance tomography (EIT) and with ventilator-embedded pressure–volume loop in severe acute respiratory distress syndrome (ARDS)
A total of 24 consecutive severe ARDS patients were included for the EIT group and examined prospectively. (Demographics are summarized in Table 1.) For the control group, data from severe ARDS patients treated in our intensive care unit (ICU) in 2016 were included from our database and analyzed
Hospital survival and weaning success rates were higher in the EIT group but the differences were not statistically significant. (See Fig. 3.) Log-rank test indicated that the differences in the numbers of days were insignificant (P = 0.10 and 0.24 for hospital survival (Fig. 3 left) and weaning success curves (Fig. 3 right, respectively)
Summary
The study objective was to compare titration of positive end-expiratory pressure (PEEP) with electri‐ cal impedance tomography (EIT) and with ventilator-embedded pressure–volume loop in severe acute respiratory distress syndrome (ARDS). When low tidal volume is selected, the driving pressure depends on the respiratory system compliance (Crs). Significant differences may have not been revealed due to the small number of studied subjects (n = 14) and high variation among them. These strategies for setting PEEP aimed at improving oxygenation, increasing alveolar recruitment while limiting hyperinflation; they did not significantly reduce mortality. A recent study claimed that a strategy with lung recruitment and titrated PEEP compared with low PEEP increased mortality [12]. With the concerns regarding the study design, methodology, and data analyses, the results of the study are considered questionable [13]
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