In:
Critical Care, Springer Science and Business Media LLC, Vol. 27, No. 1 ( 2023-08-17)
Abstract:
The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects of awake prone position in patients with acute hypoxemic respiratory failure. Methods Fifteen patients with acute hypoxemic respiratory failure and PaO 2 /FiO 2 〈 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (Δ P ES ), transpulmonary driving pressure (Δ P L ), respiratory rate and esophageal pressure simplified pressure–time product per minute (sPTP ES ) by esophageal manometry, tidal volume ( V T ), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain ( V T /EELI) and pendelluft extent through electrical impedance tomography. Results Compared to supine position, prone position increased PaO 2 /FiO 2 (median [Interquartile range] 104 mmHg [76–129] vs. 74 [69–93], p 〈 0.001), reduced respiratory rate (24 breaths/min [22–26] vs. 27 [26–30] , p = 0.05) and increased Δ P ES (12 cmH 2 O [11–13] vs. 9 [8–12] , p = 0.04) with similar sPTP ES (131 [75–154] cmH 2 O s min −1 vs. 105 [81–129], p 〉 0.99) and Δ P L (9 [7–11] cmH 2 O vs. 8 [5–9], p = 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH 2 O s arbitrary units −3 [4–11] vs. 6 [4–9] , p = 0.05; 0.53 s [0.32–61] vs. 0.40 [0.37–0.44] , p = 0.03). Prone position increased EELI (3887 arbitrary units [3414–8547] vs. 1456 [959–2420] , p = 0.002) and promoted V T distribution towards dorsal lung regions without affecting V T size and lung compliance: this generated lower dynamic strain (0.21 [0.16–0.24] vs. 0.38 [0.30–0.49] , p = 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% [7–57] of V T in prone vs. 31% [14–55] in supine position, p 〉 0.99). Conclusions Prone position improves oxygenation, increases EELI and promotes V T distribution towards dependent lung regions without affecting V T size, Δ P L , lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases Δ P ES because of positional increases in airway resistance and prolonged expiratory time. Because high Δ P ES is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense Δ P ES . Clinical trail registeration : The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.
Type of Medium:
Online Resource
ISSN:
1364-8535
DOI:
10.1186/s13054-023-04600-9
Language:
English
Publisher:
Springer Science and Business Media LLC
Publication Date:
2023
detail.hit.zdb_id:
2051256-9
