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Busana M, Rau A, Lazzari S, Gattarello S, Cressoni M, Biggemann L, Harnisch LO, Giosa L, Vogt A, Saager L, Lotz J, Meller B, Meissner K, Gattinoni L, Moerer O. Causes of Hypoxemia in COVID-19 Acute Respiratory Distress Syndrome: A Combined Multiple Inert Gas Elimination Technique and Dual-energy Computed Tomography Study. Anesthesiology 2024; 140:251-260. [PMID: 37656772 DOI: 10.1097/aln.0000000000004757] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/03/2023]
Abstract
BACKGROUND Despite the fervent scientific effort, a state-of-the art assessment of the different causes of hypoxemia (shunt, ventilation-perfusion mismatch, and diffusion limitation) in COVID-19 acute respiratory distress syndrome (ARDS) is currently lacking. In this study, the authors hypothesized a multifactorial genesis of hypoxemia and aimed to measure the relative contribution of each of the different mechanism and their relationship with the distribution of tissue and blood within the lung. METHODS In this cross-sectional study, the authors prospectively enrolled 10 patients with COVID-19 ARDS who had been intubated for less than 7 days. The multiple inert gas elimination technique (MIGET) and a dual-energy computed tomography (DECT) were performed and quantitatively analyzed for both tissue and blood volume. Variables related to the respiratory mechanics and invasive hemodynamics (PiCCO [Getinge, Sweden]) were also recorded. RESULTS The sample (51 ± 15 yr; Pao2/Fio2, 172 ± 86 mmHg) had a mortality of 50%. The MIGET showed a shunt of 25 ± 16% and a dead space of 53 ± 11%. Ventilation and perfusion were mismatched (LogSD, Q, 0.86 ± 0.33). Unexpectedly, evidence of diffusion limitation or postpulmonary shunting was also found. In the well aerated regions, the blood volume was in excess compared to the tissue, while the opposite happened in the atelectasis. Shunt was proportional to the blood volume of the atelectasis (R2 = 0.70, P = 0.003). V˙A/Q˙T mismatch was correlated with the blood volume of the poorly aerated tissue (R2 = 0.54, P = 0.016). The overperfusion coefficient was related to Pao2/Fio2 (R2 = 0.66, P = 0.002), excess tissue mass (R2 = 0.84, P < 0.001), and Etco2/Paco2 (R2 = 0.63, P = 0.004). CONCLUSIONS These data support the hypothesis of a highly multifactorial genesis of hypoxemia. Moreover, recent evidence from post-mortem studies (i.e., opening of intrapulmonary bronchopulmonary anastomosis) may explain the findings regarding the postpulmonary shunting. The hyperperfusion might be related to the disease severity. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Mattia Busana
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Anna Rau
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Stefano Lazzari
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany; and Institute for Treatment and Research San Raffaele Scientific Institute, Department of Anesthesia and Intensive Care, Milan, Italy
| | - Simone Gattarello
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany; and Institute for Treatment and Research San Raffaele Scientific Institute, Department of Anesthesia and Intensive Care, Milan, Italy
| | - Massimo Cressoni
- Unit of Radiology, Institute for Treatment and Research Policlinico San Donato, Milan, Italy
| | - Lorenz Biggemann
- Institute for Diagnostic and Interventional Radiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Lars-Olav Harnisch
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Lorenzo Giosa
- Centre for Human and Applied Physiological Sciences, King's College London, London, United Kingdom
| | - Andreas Vogt
- Department of Anaesthesiology and Pain Medicine, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Leif Saager
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany; and Outcomes Research Consortium, Cleveland, Ohio
| | - Joachim Lotz
- Institute for Diagnostic and Interventional Radiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Birgit Meller
- Clinic of Nuclear Medicine, University Medical Center of Göttingen, Göttingen, Germany
| | - Konrad Meissner
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Luciano Gattinoni
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
| | - Onnen Moerer
- Department of Anesthesiology, University Medical Center of Göttingen, Göttingen, Germany
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