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

Abstract

ObjectiveTo assess the diagnostic accuracy of peripheral capillary oxygen saturation (SpO2) while breathing room air for 5 min (the ‘Air-Test’) in detecting postoperative atelectasis.DesignProspective cohort study. Diagnostic accuracy was assessed by measuring the agreement between the index test and the reference standard CT scan images.SettingPostanaesthetic care unit in a tertiary hospital in Spain.ParticipantsThree 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.InterventionThe 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 measuresThe 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.ResultsThe 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).ConclusionThe Air-Test may represent an accurate, simple, inexpensive and non-invasive method for diagnosing postoperative atelectasis.Trial RegistrationNCT02650037.

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“…Lastly, the de nition of substantial atelectasis was not validated by previous studies. Although previous studies have used lung ultrasound as a diagnostic tool for atelectasis (15,19,21,(29)(30)(31), the criteria for substantial atelectasis are yet to be established.…”

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Diagnosis and treatment of obstructive atelectasis after general anesthesia in a patient with abscess in the maxillofacial area: A case report

“…Persistent wheezing raises the suspicion of atelectasis [ 3 ]. Hypoxia is a direct result of atelectasis, and thus, measurement of SPO 2 with pulse oximetry is the best approach to diagnosing atelectasis, given its low cost, minimal invasiveness, and immediate results [ 4 ]. Monitoring oxygen saturation trends using pulse oximetry can raise the suspicion for atelectasis when hypoxia is present [ 4 5 ].…”

“…Postoperative atelectasis was observed in 27% of maxillofacial surgery patients [ 9 ]. Atelectasis can occur at any time between before surgery to days after surgery, and untreated atelectasis can lead to complications, such as pneumonia, acute pulmonary injury, and reintubation and extubation failure [ 4 ].…”