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BMJ Open. 2017 May 29;7(5):e015560. doi: 10.1136/bmjopen-2016-015560.

The accuracy of postoperative, non-invasive Air-Test to diagnose atelectasis in healthy patients after surgery: a prospective, diagnostic pilot study.

Author information

1
Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain.
2
Anesthesiology and Critical Care, Consorci Hospital General Universitari de Valencia, Valencia, Spain.
3
Department of Anesthesiology, Hospital Privado de Comunidad, Mar de Plata, Argentina.
4
Uppsala Universitet, Uppsala, Sweden.
5
CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
6
Anesthesiology and Critical Care, Hospital Universitari Germans Trias i Pujol, Badalona, Spain.
7
Department of Radiology, Hospital Clinico Universitario Valencia, Valencia, Spain.
8
ITACA Institute (Group IBIME), Universidad Politécnica, Valencia, Spain.
9
INCLIVA Clinical Research Institute, Valencia, Spain.
10
Research Unit, Hospital Universitario Dr. Negrin, Las Palmas de Gran Canaria, Spain.

Abstract

OBJECTIVE:

To assess the diagnostic accuracy of peripheral capillary oxygen saturation (SpO2) while breathing room air for 5 min (the 'Air-Test') in detecting postoperative atelectasis.

DESIGN:

Prospective cohort study. Diagnostic accuracy was assessed by measuring the agreement between the index test and the reference standard CT scan images.

SETTING:

Postanaesthetic care unit in a tertiary hospital in Spain.

PARTICIPANTS:

Three hundred and fifty patients from 12 January to 7 February 2015; 170 patients scheduled for surgery under general anaesthesia who were admitted into the postsurgical unit were included.

INTERVENTION:

The Air-Test was performed in conscious extubated patients after a 30 min stabilisation period during which they received supplemental oxygen therapy via a venturi mask. The Air-Test was defined as positive when SpO2 was ≤96% and negative when SpO2 was ≥97%. Arterial blood gases were measured in all patients at the end of the Air-Test. In the subsequent 25 min, the presence of atelectasis was evaluated by performing a CT scan in 59 randomly selected patients.

MAIN OUTCOME MEASURES:

The primary study outcome was assessment of the accuracy of the Air-Test for detecting postoperative atelectasis compared with the reference standard. The secondary outcome was the incidence of positive Air-Test results.

RESULTS:

The Air-Test diagnosed postoperative atelectasis with an area under the receiver operating characteristic curve of 0.90 (95% CI 0.82 to 0.98) with a sensitivity of 82.6% and a specificity of 87.8%. The presence of atelectasis was confirmed by CT scans in all patients (30/30) with positive and in 5 patients (17%) with negative Air-Test results. Based on the Air-Test, postoperative atelectasis was present in 36% of the patients (62 out of 170).

CONCLUSION:

The Air-Test may represent an accurate, simple, inexpensive and non-invasive method for diagnosing postoperative atelectasis.

TRIAL REGISTRATION:

NCT02650037.

KEYWORDS:

SpO2; adult anaesthesia; adult intensive & critical care; atelectasis; oxygenation; postoperative

PMID:
28554935
PMCID:
PMC5623366
DOI:
10.1136/bmjopen-2016-015560
[Indexed for MEDLINE]
Free PMC Article

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