Laura Pla1, Sergio Berdún1, Mònica Mir2,3,4, Lourders Rivas3, Sandrine Miserere3, Samuel Dulay3, Josep Samitier2,3,4, Elisenda Eixarch1,5,6, Miriam Illa7,8, Eduard Gratacós1,5,6,9. 1. BCNatal | Fetal Medicine Research Center (Hospital Clínic and Hospital Sant Joan de Déu), Universitat de Barcelona, Barcelona, Spain. 2. Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales Y Nanomedicina (CIBER-BBN), Monforte de Lemos 3-5, Pabellón 11, 28029, Madrid, Spain. 3. Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC) Barcelona Institute of Science and Technology (BIST), 12 Baldiri Reixac 15-21, 08028, Barcelona, Spain. 4. Department of Electronics and Biomedical Engineering, University of Barcelona, Martí I Franquès 1, 08028, Barcelona, Spain. 5. Institut D'Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Barcelona, Spain. 6. Centre for Biomedical Research On Rare Diseases (CIBER-ER), Barcelona, Spain. 7. BCNatal | Fetal Medicine Research Center (Hospital Clínic and Hospital Sant Joan de Déu), Universitat de Barcelona, Barcelona, Spain. miriamil@clinic.cat. 8. Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain. miriamil@clinic.cat. 9. Institut de Recerca Sant Joan de Déu, Esplugues de Llobregat, Spain.
Abstract
BACKGROUND: One of the most prevalent causes of fetal hypoxia leading to stillbirth is placental insufficiency. Hemodynamic changes evaluated with Doppler ultrasound have been used as a surrogate marker of fetal hypoxia. However, Doppler evaluation cannot be performed continuously. As a first step, the present work aimed to evaluate the performance of miniaturized electrochemical sensors in the continuous monitoring of oxygen and pH changes in a model of acute hypoxia-acidosis. METHODS: pH and oxygen electrochemical sensors were evaluated in a ventilatory hypoxia rabbit model. The ventilator hypoxia protocol included 3 differential phases: basal (100% FiO2), the hypoxia-acidosis period (10% FiO2) and recovery (100% FiO2). Sensors were tested in blood tissue (ex vivo sensing) and in muscular tissue (in vivo sensing). pH electrochemical and oxygen sensors were evaluated on the day of insertion (short-term evaluation) and pH electrochemical sensors were also tested after 5 days of insertion (long-term evaluation). pH and oxygen sensing were registered throughout the ventilatory hypoxia protocol (basal, hypoxia-acidosis, and recovery) and were compared with blood gas metabolites results from carotid artery catheterization (obtained with the EPOC blood analyzer). Finally, histological assessment was performed on the sensor insertion site. One-way ANOVA was used for the analysis of the evolution of acid-based metabolites and electrochemical sensor signaling results; a t-test was used for pre- and post-calibration analyses; and chi-square analyses for categorical variables. RESULTS: At the short-term evaluation, both the pH and oxygen electrochemical sensors distinguished the basal and hypoxia-acidosis periods in both the in vivo and ex vivo sensing. However, only the ex vivo sensing detected the recovery period. In the long-term evaluation, the pH electrochemical sensor signal seemed to lose sensibility. Finally, histological assessment revealed no signs of alteration on the day of evaluation (short-term), whereas in the long-term evaluation a sub-acute inflammatory reaction adjacent to the implantation site was detected. CONCLUSIONS: Miniaturized electrochemical sensors represent a new generation of tools for the continuous monitoring of hypoxia-acidosis, which is especially indicated in high-risk pregnancies. Further studies including more tissue-compatible material would be required in order to improve long-term electrochemical sensing.
BACKGROUND: One of the most prevalent causes of fetal hypoxia leading to stillbirth is placental insufficiency. Hemodynamic changes evaluated with Doppler ultrasound have been used as a surrogate marker of fetal hypoxia. However, Doppler evaluation cannot be performed continuously. As a first step, the present work aimed to evaluate the performance of miniaturized electrochemical sensors in the continuous monitoring of oxygen and pH changes in a model of acute hypoxia-acidosis. METHODS: pH and oxygen electrochemical sensors were evaluated in a ventilatory hypoxia rabbit model. The ventilator hypoxia protocol included 3 differential phases: basal (100% FiO2), the hypoxia-acidosis period (10% FiO2) and recovery (100% FiO2). Sensors were tested in blood tissue (ex vivo sensing) and in muscular tissue (in vivo sensing). pH electrochemical and oxygen sensors were evaluated on the day of insertion (short-term evaluation) and pH electrochemical sensors were also tested after 5 days of insertion (long-term evaluation). pH and oxygen sensing were registered throughout the ventilatory hypoxia protocol (basal, hypoxia-acidosis, and recovery) and were compared with blood gas metabolites results from carotid artery catheterization (obtained with the EPOC blood analyzer). Finally, histological assessment was performed on the sensor insertion site. One-way ANOVA was used for the analysis of the evolution of acid-based metabolites and electrochemical sensor signaling results; a t-test was used for pre- and post-calibration analyses; and chi-square analyses for categorical variables. RESULTS: At the short-term evaluation, both the pH and oxygen electrochemical sensors distinguished the basal and hypoxia-acidosis periods in both the in vivo and ex vivo sensing. However, only the ex vivo sensing detected the recovery period. In the long-term evaluation, the pH electrochemical sensor signal seemed to lose sensibility. Finally, histological assessment revealed no signs of alteration on the day of evaluation (short-term), whereas in the long-term evaluation a sub-acute inflammatory reaction adjacent to the implantation site was detected. CONCLUSIONS: Miniaturized electrochemical sensors represent a new generation of tools for the continuous monitoring of hypoxia-acidosis, which is especially indicated in high-risk pregnancies. Further studies including more tissue-compatible material would be required in order to improve long-term electrochemical sensing.
Authors: C Morgan; S J Newell; D A Ducker; J Hodgkinson; D K White; C J Morley; J M Church Journal: Arch Dis Child Fetal Neonatal Ed Date: 1999-03 Impact factor: 5.747
Authors: Siti Fatimah Abdul Halim; Zulkarnay Zakaria; Jaysuman Pusppanathan; Anas Mohd Noor; Ahmad Nasrul Norali; Mohd Hafiz Fazalul Rahiman; Siti Zarina Mohd Muji; Ruzairi Abdul Rahim; Engku Ismail Engku-Husna; Muhamad Khairul Ali Hassan; Muhammad Juhairi Aziz Safar; Ahmad Faizal Salleh; Mohd Hanafi Mat Som Journal: Sensors (Basel) Date: 2022-02-10 Impact factor: 3.576