Lung Recruitment Can Improve Oxygenation in Patients Ventilated in Continuous Positive Airway Pressure/Pressure Support Mode

Abstract

BackgroundRecruitment maneuvers are often used in critical care patients with hypoxemic respiratory failure. Although continuous positive airway pressure/pressure support (CPAP/PS) ventilation is a frequently used approach, but whether lung recruitment also improves oxygenation in spontaneously breathing patients has not been investigated yet. The primary objective was to analyze the effect of recruitment maneuver on oxygenation in patients ventilated in CPAP/PS mode.MethodsFollowing baseline measurements PEEP was increased by 5 cmH2O. Recruitment maneuver was applied for 40 s with 40 cmH2O of PS. Measurements of the difference in PaO2/FiO2 and airway parameters measured by the ventilator were recorded immediately after recruitment then 15 and 30 min later. Thirty patients ventilated in CPAP/PS mode with a PEEP ≥5 cmH2O were enrolled in this prospective, observational study if their PaO2/FiO2 ratio was <300 mmHg or required an FiO2 >0.5.ResultsFollowing recruitment maneuver patients were considered as non-responders (NR, n = 15) if difference of PaO2/FiO2 <20% and responders (R, n = 15) if difference of PaO2/FiO2 ≥20%. In the NR-group, PaO2/FiO2 decreased non-significantly from baseline: median [interquartile], PaO2/FiO2 = 176 [120–186] vs. after recruitment: 169 [121–182] mmHg, P = 0.307 while in the R-group there was significant improvement: 139 [117–164] vs. 230 [211–323] mmHg, P = 0.01. At the same time points, dead space to tidal volume ratio (Vds/Vte) significantly increased in the NR-group Vds/Vte = 32 [27–37] vs. 36 [25–42]%, P = 0.013 but no significant change was observed in the R-group: 26 [22–34] vs. 27 [24–33]%, P = 0.386.ConclusionRecruitment maneuver improved PaO2/FiO2 ratio by ≥20% in 50% of patients ventilated in CPAP/PS mode.

Improving oxygenation in spontaneously breathing patients with atelectatic lung

“…These results are also in accord with those reported in patients on controlled mechanical ventilation 25 but it also contradicts those in which etiology did not seem to matter. 26 However, in this recent study by Grasso et al, the sample size was small (11 per group) and none of the patients were admitted due to acute heart failure. Nevertheless, the success of recruitment as far as oxygenation is concerned in spontaneously breathing patients having developed hypoxemic respiratory failure due to acute heart failure is an important finding and should be investigated further.…”

“…29 [25][26][27][28][29][30][31][32][33][34][35] 2 were significantly higher at all time-points with a significant decrease in pH. There was a tendency of significantly elevated HCO 3 -levels at t [2][3][4] with no significant increase in BE and lactate levels showed minimal change.…”

“…Although it was not statistically significant, but these results are similar to that of reported by Grasso et al, where the length of mechanical ventilation was significantly shorter in those patients who responded for recruitment manoeuvers. 26 It is well known that not every lung responds for recruitment and unnecessary manoeuvers may lead to adverse effects. 12,33 Several methods had been evaluated of which chest CT scan remains the gold standard warranting the direct visualization of the recruitable lung tissue.…”

“…It is well known that not every lung responds for recruitment and unnecessary maneuvers may lead to adverse effects (8,26). Several methods had been evaluated of which chest CT scan remains the gold standard warranting the direct visualization of the recruitable lung tissue (8).…”

“…If haemodynamic changes are solely monitored by mean arterial pressure (MAP) during lung recruitment manoeuvre, one can theoretically miss relevant alterations in the systemic circulation. Recent investigations concluded that simple haemodynamic parameters like MAP or heart rate did not show any significant change during and after various recruitment interventions [17,21,26]. However, applying advanced invasive haemodynamic monitoring, relevant changes in the systemic circulation can be observed [14].…”