Reduced levels of pulmonary surfactant in COVID-19 ARDS.

To provide novel data on surfactant levels in adult COVID-19 patients, we collected bronchoalveolar lavage fluid less than 72 h after intubation and used Fourier Transform Infrared Spectroscopy to measure levels of dipalmitoylphosphatidylcholine (DPPC). A total of eleven COVID-19 patients with moderate-to-severe ARDS (CARDS) and 15 healthy controls were included. CARDS patients had lower DPPC levels than healthy controls. Moreover, a principal component analysis was able to separate patient groups into distinguishable subgroups. Our findings indicate markedly impaired pulmonary surfactant levels in COVID-19 patients, justifying further studies and clinical trials of exogenous surfactant.

[Surfactant therapy of respiratory distress syndrome].

This review gives a summary of the development of a method to measure lung surfactant on gastric aspirate at birth in premature infants with the purpose to threat respiratory distress syndrome early with targeted surfactant. Machine learning was used to create the algorithm, and a point-of-care spectrometer was constructed for use in the delivery room. The sensitivity was 91% and specificity 79% in a clinical trial. The same method was used to measure surfactant in tracheal fluid in patients with COVID-19 since lung surfactant may be diminished in these patients.

Bronchopulmonary dysplasia predicted at birth by artificial intelligence.

AIM: To develop a fast bedside test for prediction and early targeted intervention of bronchopulmonary dysplasia (BPD) to improve the outcome. METHODS: In a multicentre study of preterm infants with gestational age 24-31 weeks, clinical data present at birth were combined with spectral data of gastric aspirate samples taken at birth and analysed using artificial intelligence. The study was designed to develop an algorithm to predict development of BPD. The BPD definition used was the consensus definition of the US National Institutes of Health: Requirement of supplemental oxygen for at least 28 days with subsequent assessment at 36 weeks postmenstrual age. RESULTS: Twenty-six (43%) of the 61 included infants developed BPD. Spectral data analysis of the gastric aspirates identified the most important wave numbers for classification and surfactant treatment, and birth weight and gestational age were the most important predictive clinical data. By combining these data, the resulting algorithm for early diagnosis of BPD had a sensitivity of 88% and a specificity of 91%. CONCLUSION: A point-of-care test to predict subsequent development of BPD at birth has been developed using a new software algorithm allowing early targeted intervention of BPD which could improve the outcome.

Predicting respiratory distress syndrome at birth using fast test based on spectroscopy of gastric aspirates. 1. Biochemical part.

AIM: To develop a fast bedside lung maturity test. METHODS: Gastric aspirates obtained from premature infants contain lamellar bodies, carrying lung surfactant. To estimate lung maturity, we isolated lamellar bodies from fresh gastric aspirates by centrifugation. Erythrocytes and other cells were lysed by adding water and discarded subsequently with the supernatant. Mid-infrared spectroscopy was then performed to measure the lung maturity as lecithin-sphingomyelin ratio. Lecithin was determined as dipalmitoylphosphatidylcholine, the most surface-active phospholipid. Algorithms to measure lecithin and sphingomyelin concentrations in fresh gastric aspirates were developed on aspirates from 140 premature infants. Each gastric aspirate sample was divided into two samples: one for mass spectrometry as reference and one for spectroscopy. Development of the algorithm is described in detail in Appendix S1. RESULTS: Gastric aspirates stored at 4-5°C avoid flocculation of proteins and phospholipids in contrast to when the aspirates were frozen and thawed. Omission of freezing and concentration of the lung surfactant by centrifugation combined with diminished influence of proteins improves the spectroscopic measurement of lecithin-sphingomyelin ratio. Measurement of lecithin-sphingomyelin ratio by the new method was performed within 10-15 minutes. CONCLUSION: We present a new fast bedside lung maturity test on fresh gastric aspirate for early targeted surfactant treatment.

Predicting respiratory distress syndrome at birth using a fast test based on spectroscopy of gastric aspirates: 2. Clinical part.

AIM: To evaluate the accuracy of our new rapid point-of-care (POC) test for lung maturity. The method as we describe in an accompanying article was developed with the purpose of improving the outcome from respiratory distress syndrome (RDS). The test enables the delivery of surfactant in infants with immature lungs already at birth and ensures that infants with mature lungs are not treated unnecessarily. METHODS: Fresh gastric aspirate (GAS) was sampled at birth in a cohort of preterm infants with gestational ages ranging between 24 and 31 completed weeks for lung surfactant measurement as lecithin-sphingomyelin ratio (L/S). L/S was prospectively compared with RDS development. The clinical outcome was blinded for the investigators of L/S. The time for analysis was <15 minutes. RESULTS: GAS was obtained from 72 infants. Forty-four (61%) developed RDS. The cut-off for L/S was 3.05; predicting RDS with a sensitivity of 91% and specificity of 79%. CONCLUSION: The new improved spectroscopic L/S method of lung maturity on GAS has high sensitivity. The method is designed for use as a POC test at birth, and a spectroscopic prototype has been developed for bedside use. Clinical trials with this new lung maturity test are planned.

Rapid test for lung maturity, based on spectroscopy of gastric aspirate, predicted respiratory distress syndrome with high sensitivity.

AIM: Respiratory distress syndrome (RDS) is a major cause of mortality and morbidity in premature infants. By the time symptoms appear, it may already be too late to prevent a severe course, with bronchopulmonary dysplasia or mortality. We aimed to develop a rapid test of lung maturity for targeting surfactant supplementation. METHODS: Concentrations of the most surface-active lung phospholipid dipalmitoylphosphatidylcholine and sphingomyelin in gastric aspirates from premature infants were measured by mass spectrometry and expressed as the lecithin/sphingomyelin ratio (L/S). The same aspirates were analysed with mid-infrared spectroscopy. Subsequently, L/S was measured in gastric aspirates and oropharyngeal secretions from another group of premature infants using spectroscopy and the results were compared with RDS development. The 10-minute analysis required 10 µL of aspirate. RESULTS: An L/S algorithm was developed based on 89 aspirates. Subsequently, gastric aspirates were sampled in 136 infants of 24-31 weeks of gestation and 61 (45%) developed RDS. The cut-off value of L/S was 2.2, sensitivity was 92%, and specificity was 73%. In 59 cases, the oropharyngeal secretions had less valid L/S than gastric aspirate results. CONCLUSION: Our rapid test for lung maturity, based on spectroscopy of gastric aspirate, predicted RDS with high sensitivity.