uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Minimizing atelectasis formation during general anaesthesia-oxygen washout is a non-essential supplement to PEEP
Västerås & Koping Hosp, Dept Anaesthesia & Intens Care, Västerås, Sweden..
Vasteras Hosp, Dept Radiol, Västerås, Sweden..
Clin Res Ctr, Västerås, Sweden..
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Show others and affiliations
2017 (English)In: Upsala Journal of Medical Sciences, ISSN 0300-9734, E-ISSN 2000-1967, Vol. 122, no 2, p. 92-98Article in journal (Refereed) Published
Abstract [en]

Background: Following preoxygenation and induction of anaesthesia, most patients develop atelectasis. We hypothesized that an immediate restoration to a low oxygen level in the alveoli would prevent atelectasis formation and improve oxygenation during the ensuing anaesthesia. Methods: We randomly assigned 24 patients to either a control group (n=12) or an intervention group (n=12) receiving an oxygen washout procedure directly after intubation. Both groups were, depending on body mass index, ventilated with a positive end-expiratory pressure (PEEP) of 6-8 cmH(2)O during surgery. The atelectasis area was studied by computed tomography before emergence. Oxygenation levels were evaluated by measuring blood gases and calculating estimated venous admixture (EVA). Results: The atelectasis areas expressed as percentages of the total lung area were 2.0 (1.5-2.7) (median [interquartile range]) and 1.8 (1.4-3.3) in the intervention and control groups, respectively. The difference was non-significant, and also oxygenation was similar between the two groups. Compared to oxygenation before the start of anaesthesia, oxygenation at the end of surgery was improved in the intervention group, mean (SD) EVA from 7.6% (6.6%) to 3.9% (2.9%) (P=.019) and preserved in the control group, mean (SD) EVA from 5.0% (5.3%) to 5.6% (7.1%) (P=.59). .Conclusion: Although the oxygen washout restored a low pulmonary oxygen level within minutes, it did not further reduce atelectasis size. Both study groups had small atelectasis and good oxygenation. These results suggest that a moderate PEEP alone is sufficient to minimize atelectasis and maintain oxygenation in healthy patients.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD , 2017. Vol. 122, no 2, p. 92-98
Keywords [en]
Atelectasis, computed tomography, general anaesthesia, oxygenation, PEEP, protective ventilation, ventilator settings
National Category
Anesthesiology and Intensive Care
Identifiers
URN: urn:nbn:se:uu:diva-323496DOI: 10.1080/03009734.2017.1294635ISI: 000401756500004PubMedID: 28434271OAI: oai:DiVA.org:uu-323496DiVA, id: diva2:1114213
Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2019-04-08Bibliographically approved
In thesis
1. Pulmonary Atelectasis in General Anaesthesia: Clinical Studies on the Counteracting Effects of Positive End-Expiratory Pressure
Open this publication in new window or tab >>Pulmonary Atelectasis in General Anaesthesia: Clinical Studies on the Counteracting Effects of Positive End-Expiratory Pressure
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Partial lung collapse, i.e., pulmonary atelectasis, is common during general anaesthesia. The main causal mechanism is reduced lung volume with airway closure and subsequent gas absorption from preoxygenated alveoli. Atelectasis impairs oxygenation and forms the pathophysiological basis for postoperative pulmonary complications. Positive end-expiratory pressure (PEEP) counteracts the loss in lung volume, but its role in preventing atelectasis during anaesthesia is not clear.

All studies included in this thesis were prospective randomized clinical trials. In the first study, oxygenation was used as a surrogate measure of atelectasis in obese patients undergoing laparoscopic gastric bypass. The subsequent studies used single-slice computed tomography (CT) to evaluate atelectasis in healthy patients undergoing non-abdominal surgery.

Paper I: We studied the use of continuous positive airway pressure (CPAP) and PEEP during induction of anaesthesia and a reduced inspired oxygen fraction (FiO2) during emergence. Oxygenation was maintained in the group that received CPAP during induction, followed by a PEEP of 10 cmH2O. Postoperative oxygenation was impaired in the group that received a high FiO2 during emergence.

Paper II: An early oxygen washout manoeuvre to quickly restore nitrogen levels and thus stabilize the alveoli, had no effect on atelectasis at the end of surgery. Both study groups exhibited small atelectasis after being ventilated with a moderate PEEP of 6-8 cmH2O during anaesthesia.

Paper III: The effect of PEEP versus zero PEEP on atelectasis formation and oxygenation at the end of surgery was compared. The PEEP group maintained oxygenation better and exhibited less atelectasis than the zero-PEEP group, with atelectasis involving a median 1.8% of total lung area compared with 4.6% in the zero-PEEP group (P = 0.002).

Paper IV: Postoperative atelectasis was compared between a group in which PEEP was maintained during emergence preoxygenation with FiO2 1.0 and a group in which PEEP was withdrawn just before the start of emergence preoxygenation with FiO2 1.0. The two groups had small atelectasis when fully awake at 30 min after extubation, with no statistically significant difference between them.  

In conclusion, preserved end-expiratory lung volume is the key to avoiding atelectasis, in particular when an increased oxygen reserve is required during airway manipulation. PEEP is both necessary and sufficient to minimize atelectasis in healthy patients undergoing non-abdominal surgery.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2019. p. 63
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1566
Keywords
General anaesthesia, pulmonary atelectasis, positive end-expiratory pressure, oxygen, computed tomography, continuous positive airway pressure, mechanical ventilation
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-380317 (URN)978-91-513-0635-3 (ISBN)
Public defence
2019-05-31, Vårdskolans aula, ingång 21, Västmanlands sjukhus Västerås, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2019-05-10 Created: 2019-04-08 Last updated: 2019-06-18

Open Access in DiVA

fulltext(1202 kB)89 downloads
File information
File name FULLTEXT01.pdfFile size 1202 kBChecksum SHA-512
773b3a92be67526714f00bd5f3807b87f0b761ad46d5c852f20ade8f5063d1a40a24dd8ea320eb419a7f1119b7d38c96456e87a7c443cae0ffea0232d46e4c44
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Authority records BETA

Zetterström, Henrik

Search in DiVA

By author/editor
Zetterström, Henrik
By organisation
Anaesthesiology and Intensive Care
In the same journal
Upsala Journal of Medical Sciences
Anesthesiology and Intensive Care

Search outside of DiVA

GoogleGoogle Scholar
Total: 89 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
pubmed
urn-nbn

Altmetric score

doi
pubmed
urn-nbn
Total: 493 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf