Περίληψη:
Background: Recent, large trials of high-frequency oscillation (HFO) versus conventional ventilation (CV) in acute respiratory distress syndrome (ARDS) reported negative results. This could be explained by an HFO-induced right ventricular (RV) dysfunction/failure due to high intrathoracic pressures and hypercapnia. We hypothesized that HFO strategies aimed at averting/attenuating hypercapnia, such as "low-frequency" (i.e., 4 Hz) HFO and 4-Hz HFO with tracheal-gas insufflation (HFO-TGI), may result in an improved RV function relative to "high-frequency" (i.e., 7 Hz) HFO (which may promote hypercapnia) and similar RV function relative to lung protective CV. Methods: We studied 17 patients with moderate-to-severe ARDS [PaO2-to-inspiratory O2 fraction ratio (PaO2/FiO2) < 150]. RV function was assessed by transesophageal echocardiography (TEE). Patients received 60 min of CV for TEE-guided, positive end-expiratory pressure (PEEP) "optimization" and subsequent stabilization; 60 min of 4-Hz HFO for "study mean airway pressure (mPaw)" titration to peripheral oxygen saturation ≥ 95%, without worsening RV function as assessed by TEE; 60 min of each tested HFO strategy in random order; and another 60 min of CV using the pre-HFO, TEE-guided PEEP setting. Study measurements (i.e., gas exchange, hemodynamics, and TEE data) were obtained over the last 10 min of pre-HFO CV, of each one of the three tested HFO strategies, and of post-HFO CV. Results: The mean "study HFO mPaw" was 8-10 cmH2O higher relative to pre-HFO CV. Seven-Hz HFO versus 4-Hz HFO and 4-Hz HFO-TGI resulted in higher mean ± SD right-to-left ventricular end-diastolic area ratio (RVEDA/LVEDA) (0.64 ± 0.15 versus 0.56 ± 0.14 and 0.52 ± 0.10, respectively, both p < 0.05). Higher diastolic/systolic eccentricity indexes (1.33 ± 0.19/1.42 ± 0.17 versus 1.21 ± 0.10/1.26 ± 0.10 and 1.17 ± 0.11/1.17 ± 0.13, respectively, all p < 0.05). Seven-Hz HFO resulted in 18-28% higher PaCO2 relative to all other ventilatory strategies (all p < 0.05). Four-Hz HFO-TGI versus pre-HFO CV resulted in 15% lower RVEDA/LVEDA, and 7%/10% lower diastolic/systolic eccentricity indexes (all p < 0.05). Mean PaO2/FiO2 improved by 77-80% during HFO strategies versus CV (all p < 0.05). Mean cardiac index varied by ≤ 10% among strategies. Percent changes in PaCO2 among strategies were predictive of concurrent percent changes in measures of RV function (R 2 = 0.21-0.43). Conclusions: In moderate-to-severe ARDS, "short-term" 4-Hz HFO strategies resulted in better RV function versus 7-Hz HFO, partly attributable to improved PaCO2 control, and similar or improved RV function versus CV. Trial registration: This study was registered 40 days prior to the enrollment of the first patient at ClinicalTrials.gov, ID no. NCT02027129 , Principal Investigator Spyros D. Mentzelopoulos, date of registration January 3, 2014. © 2018 The Author(s).
Συγγραφείς:
Mentzelopoulos, S.D.
Anninos, H.
Malachias, S.
Zakynthinos, S.G.
Λέξεις-κλειδιά:
adult; adult respiratory distress syndrome; airway pressure; Article; cardiac index; clinical article; clinical trial; comparative study; crossover procedure; female; gas exchange; heart left ventricle; heart output; heart ventricle function; hemodynamics; high frequency oscillation; human; hypercapnia; male; mean arterial pressure; positive end expiratory pressure; priority journal; transesophageal echocardiography
