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Pulmonary Atelectas...
Pulmonary Atelectasis in General Anaesthesia : Clinical Studies on the Counteracting Effects of Positive End-Expiratory Pressure
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- Östberg, Erland, 1971- (författare)
- Uppsala universitet,Centrum för klinisk forskning, Västerås
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- Enlund, Mats, Docent (preses)
- Uppsala universitet,Anestesiologi och intensivvård,Centrum för klinisk forskning, Västerås,Uppsala kliniska forskningscentrum (UCR)
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- Edmark, Lennart, Med. Dr. (preses)
- Uppsala universitet,Centrum för klinisk forskning, Västerås,Klinisk fysiologi
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- Lindgren, Sophie, Docent (opponent)
- Sahlgrenska akademin, Göteborgs universitet
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(creator_code:org_t)
- ISBN 9789151306353
- Uppsala : Acta Universitatis Upsaliensis, 2019
- Engelska 63 s.
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Serie: Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, 1651-6206 ; 1566
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Abstract
Ämnesord
Stäng
- 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.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Klinisk medicin -- Anestesi och intensivvård (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Clinical Medicine -- Anesthesiology and Intensive Care (hsv//eng)
Nyckelord
- General anaesthesia
- pulmonary atelectasis
- positive end-expiratory pressure
- oxygen
- computed tomography
- continuous positive airway pressure
- mechanical ventilation
- Anestesiologi och intensivvård
- Anaesthesiology and Intensive Care
Publikations- och innehållstyp
- vet (ämneskategori)
- dok (ämneskategori)
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