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Positive End-expiratory Pressure and Postoperative Atelectasis: A Randomized Controlled Trial.
Anesthesiology. 2019 10; 131(4):809-817.A

Abstract

BACKGROUND

Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation preparatory to extubation makes the lung susceptible to gas absorption and alveolar collapse, especially in dependent regions being kept open by PEEP. We hypothesized that withdrawing PEEP before starting emergence preoxygenation would limit postoperative atelectasis formation.

METHODS

This was a randomized controlled evaluator-blinded trial in 30 healthy patients undergoing nonabdominal surgery under general anesthesia and mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index. A computed tomography scan at the end of surgery assessed baseline atelectasis. The study subjects were thereafter allocated to either maintained PEEP (n = 16) or zero PEEP (n = 14) during emergence preoxygenation. The primary outcome was change in atelectasis area as evaluated by a second computed tomography scan 30 min after extubation. Oxygenation was assessed by arterial blood gases.

RESULTS

Baseline atelectasis was small and increased modestly during awakening, with no statistically significant difference between groups. With PEEP applied during awakening, the increase in atelectasis area was median (range) 1.6 (-1.1 to 12.3) cm and without PEEP 2.3 (-1.6 to 7.8) cm. The difference was 0.7 cm (95% CI, -0.8 to 2.9 cm; P = 0.400). Postoperative atelectasis for all patients was median 5.2 cm (95% CI, 4.3 to 5.7 cm), corresponding to median 2.5% of the total lung area (95% CI, 2.0 to 3.0%). Postoperative oxygenation was unchanged in both groups when compared to oxygenation in the preoperative awake state.

CONCLUSIONS

Withdrawing PEEP before emergence preoxygenation does not reduce atelectasis formation after nonabdominal surgery. Despite using 100% oxygen during awakening, postoperative atelectasis is small and does not affect oxygenation, possibly conditional on an open lung during anesthesia, as achieved by intraoperative PEEP.

Authors+Show Affiliations

From the Departments of Anesthesia and Intensive Care (E.Ö., L.E.) Radiology (A.T.) the Center for Clinical Research (M.E.), Västerås Hospital, Västerås, Sweden the Department of Anesthesia and Intensive Care, Köping County Hospital, Köping, Sweden (E.Ö., L.E.) the Department of Surgical Sciences, Anesthesiology and Intensive Care (H.Z.) the Department of Medical Sciences and Clinical Physiology (G.H.), Uppsala University, Uppsala, Sweden.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31107276

Citation

Östberg, Erland, et al. "Positive End-expiratory Pressure and Postoperative Atelectasis: a Randomized Controlled Trial." Anesthesiology, vol. 131, no. 4, 2019, pp. 809-817.
Östberg E, Thorisson A, Enlund M, et al. Positive End-expiratory Pressure and Postoperative Atelectasis: A Randomized Controlled Trial. Anesthesiology. 2019;131(4):809-817.
Östberg, E., Thorisson, A., Enlund, M., Zetterström, H., Hedenstierna, G., & Edmark, L. (2019). Positive End-expiratory Pressure and Postoperative Atelectasis: A Randomized Controlled Trial. Anesthesiology, 131(4), 809-817. https://doi.org/10.1097/ALN.0000000000002764
Östberg E, et al. Positive End-expiratory Pressure and Postoperative Atelectasis: a Randomized Controlled Trial. Anesthesiology. 2019;131(4):809-817. PubMed PMID: 31107276.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Positive End-expiratory Pressure and Postoperative Atelectasis: A Randomized Controlled Trial. AU - Östberg,Erland, AU - Thorisson,Arnar, AU - Enlund,Mats, AU - Zetterström,Henrik, AU - Hedenstierna,Göran, AU - Edmark,Lennart, PY - 2019/5/21/pubmed PY - 2020/1/30/medline PY - 2019/5/21/entrez SP - 809 EP - 817 JF - Anesthesiology JO - Anesthesiology VL - 131 IS - 4 N2 - BACKGROUND: Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation preparatory to extubation makes the lung susceptible to gas absorption and alveolar collapse, especially in dependent regions being kept open by PEEP. We hypothesized that withdrawing PEEP before starting emergence preoxygenation would limit postoperative atelectasis formation. METHODS: This was a randomized controlled evaluator-blinded trial in 30 healthy patients undergoing nonabdominal surgery under general anesthesia and mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index. A computed tomography scan at the end of surgery assessed baseline atelectasis. The study subjects were thereafter allocated to either maintained PEEP (n = 16) or zero PEEP (n = 14) during emergence preoxygenation. The primary outcome was change in atelectasis area as evaluated by a second computed tomography scan 30 min after extubation. Oxygenation was assessed by arterial blood gases. RESULTS: Baseline atelectasis was small and increased modestly during awakening, with no statistically significant difference between groups. With PEEP applied during awakening, the increase in atelectasis area was median (range) 1.6 (-1.1 to 12.3) cm and without PEEP 2.3 (-1.6 to 7.8) cm. The difference was 0.7 cm (95% CI, -0.8 to 2.9 cm; P = 0.400). Postoperative atelectasis for all patients was median 5.2 cm (95% CI, 4.3 to 5.7 cm), corresponding to median 2.5% of the total lung area (95% CI, 2.0 to 3.0%). Postoperative oxygenation was unchanged in both groups when compared to oxygenation in the preoperative awake state. CONCLUSIONS: Withdrawing PEEP before emergence preoxygenation does not reduce atelectasis formation after nonabdominal surgery. Despite using 100% oxygen during awakening, postoperative atelectasis is small and does not affect oxygenation, possibly conditional on an open lung during anesthesia, as achieved by intraoperative PEEP. SN - 1528-1175 UR - https://www.unboundmedicine.com/medline/citation/31107276/Positive_End-expiratory_Pressure_and_Postoperative_Atelectasis:_A_Randomized_Controlled_Trial L2 - http://anesthesiology.pubs.asahq.org/article.aspx?doi=10.1097/ALN.0000000000002764 DB - PRIME DP - Unbound Medicine ER -